Infection Control

Online Course #9008 or #5008 - 10 Contact Hours
Author: Patti V. Hoffman, RN, BS, MPH
©2008 National Center of Continuing Education, Inc.

For your convenience, this course has been divided into 3 sections:
Below is Part 2 of 3.
Table of Contents …Review Part 1 …Part 3 …Independent Analysis …Evaluation

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Standard Precautions

The CDC Standard Precautions incorporate the principles outlined above from OSHA. In addition, CDC has promulgated recommendations regarding precautions in several specific areas.
Although it has not been specifically implicated in the transmission of HIV or other bloodborne diseases, saliva has not been removed from the list of body fluids that require the caregiver to exercise Standard Precautions. The CDC suggests that in instances of resuscitation, mouthpieces, resuscitation bags or other ventilation devices should be readily available. In all clinical settings the CDC and the American Dental Association's Council on Dental Therapeutics suggest assuming that saliva contaminated with blood can potentially carry HIV and other diseases.
There is the potential for exposure any time a puncture wound occurs from a contaminated needle, lancet, or surgical instrument. Special care should be taken when using, caring for, disinfecting, or cleaning these items. Needles should NEVER be recapped with both hands, purposely bent, broken, manipulated, or removed from disposable syringes by hand.
After use, disposable syringes and needles, scalpel blades, and all other sharps that are to be disposed of should be placed in a puncture-resistant container that is placed as close to the use area as is practical. Large bore reusable needles should be placed into a puncture-resistant container and then transported to the nearest reprocessing area. Housekeepers and other environmental workers must adhere to the same precautions when disposing of contaminated rubbish.
Specimens should be placed in leak-proof containers or bags with a biohazard warning label. Appropriate procedures must be followed for cleaning and sterilizing instruments. Never re-use disposable equipment.
About one out of every four needle stick injuries involves IV therapy equipment. Many injuries result during disassembly, but they may also occur during any of the steps of the assembly/use/discard process, including insertion into drip chambers, injection ports and IV bags.
You should be aware that needles attached to discontinued IV lines may also present a problem. The Federal government offers sanctions to discourage health facilities from continuing to use conventional devices. It is documented that the Occupational Safety and Health Administration (OSHA) has levied fines against hospitals for failure to evaluate and consider the adoption of specific engineering controls that reduce the risk of needle stick injury.
Some procedures you perform will pose a greater threat of contact with bloodborne pathogens than others. Along with OSHA, the CDC has supplied specific information concerning invasive procedures. "Characteristics of exposure-prone procedures include digital palpation of needle tip in a body cavity or the simultaneous presence of the healthcare worker's fingers and needle or other sharp instrument or object in a poorly visualized or confined anatomic site. The performance of exposure-prone procedures presents a recognized risk of percutaneous injury. If such an injury occurs, blood is likely to contact the client's body cavity, subcutaneous tissues, and/or mucous membranes."
An invasive procedure is defined as a surgical entry into tissues, cavities, or organs, or repair of major traumatic injuries:

1. In the operating room, delivery room, emergency department, or outpatient setting to include both physician and dental offices.
2. Cardiac catheterization and angiographic procedures.
3. A vaginal or cesarean delivery, or other obstetric procedures where bleeding may occur.
4. Manipulation, cutting or removal of any oral or perioral tissues, including tooth structure, where bleeding occurs or the potential for bleeding exists.

The standard blood and body fluid precautions are recommended by both the CDC and OSHA and should be the minimum for all invasive procedures.

Transmission-Based Precautions

Transmission-based precautions were designed for patients with suspected or documented infection with highly transmissible or epidemiologically important pathogens requiring additional practices beyond standard precautions. The four types of transmission-based precautions are Airborne, Droplet, Contact and Empiric precautions. They are always used in conjunction with standard precautions. Some diseases/infections with multiple routes of transmission may require a combination of transmission-based precautions: e.g., chickenpox (Varicella) requires airborne and contact precautions in addition to standard precautions. Table 4 summarizes the types of transmission precautions and the patients who require them.

Synopsis of Types of Precautions and Patients Requiring the Precautions*

Standard Precautions

Use Standard Precautions for the care of all patients

Airborne Precautions

In addition to Standard Precautions, use Airborne Precautions for patients known or suspected to have serious illnesses transmitted by airborne droplet nuclei. Examples of such illnesses include:

• Measles
• Varicella (including disseminated zoster) †
• Tuberculosis ‡

Droplet Precautions

In addition to Standard Precautions, use Droplet Precautions for patients known or suspected to have serious illnesses transmitted by large particle droplets. Examples of such illnesses include:

• Invasive Haemophilus influenzae type b disease, including meningitis, pneumonia, epiglottitis, and sepsis
• Invasive Neisseria meningitidis disease, including meningitis, pneumonia, and sepsis

Other serious bacterial respiratory infections spread by droplet transmission, including:

• Diphtheria (pharyngeal)
• Mycoplasma pneumonia
• Pertussis
• Pneumonic plague
• Streptococcal (group A) pharyngitis, pneumonia, or scarlet fever in infants and young children

Serious viral infections spread by droplet transmission, including:

• Adenovirus †
• Influenza
• Mumps
• Parvovirus B19
• Rubella

Contact Precautions

In addition to Standard Precautions, use Contact Precautions for patients known or suspected to have serious illnesses easily transmitted by direct patient contact or by contact with items in the patient's environment. Examples of such illnesses include:
Gastrointestinal, respiratory, skin, or wound infections or colonization with multidrug-resistant bacteria judged by the infection control program, based on current state, regional, or national recommendations, to be of special clinical and epidemiologic significance

Enteric infections with a low infectious dose or prolonged environmental survival, including:

• Clostridium difficile
• For diapered or incontinent patients: enterohemorrhagic Escherichia coli O157:H7, Shigella, hepatitis A, or rotavirus

Respiratory syncytial virus, parainfluenza virus, or enteroviral infections in infants and young children

Skin infections that are highly contagious or that may occur on dry skin, including:

• Diphtheria (cutaneous)
• Herpes simplex virus (neonatal or mucocutaneous)
• Impetigo
• Major (noncontained) abscesses, cellulitis, or decubiti
• Pediculosis
• Scabies
• Staphylococcal furunculosis in infants and young children
• Zoster (disseminated or in the immunocompromised host) †

Viral/hemorrhagic conjunctivitis

Viral hemorrhagic infections (Ebola, Lassa, or Marburg)*

* See Appendix A for a complete listing of infections requiring precautions, including appropriate footnotes.

† Certain infections require more than one type of precaution.

‡ See CDC's "Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities" at http://www.cdc.gov/nchstp/tb/pubs/mmwr/rr4313.pdf

From the Public Health Service, US Department of Health and Human Services, Centers for Disease Control and Prevention, Atlanta, Georgia. See Garner JS, Hospital Infection Control Practices Advisory Committee. Guideline for isolation precautions in hospitals. Infect Control Hosp Epidemiol 1996;17:53-80, and Am J Infect Control 1996;24:24-52.

Airborne Precautions
Airborne precautions are designed to reduce the risk of airborne transmission of infective agents. Airborne transmission occurs by dissemination of either airborne droplet nuclei (small particle residue of evaporated droplets that can remain suspended in the air for long periods of time) or dust particles containing the infectious agent. Organisms transmitted in this manner can be widely dispersed by air currents and may be inhaled or deposited on a susceptible host within the same room or a long distance from the source patient. Therefore, special air handling and ventilation systems are required to prevent airborne transmission. Isolation rooms used to house patients requiring airborne precautions must have negative airflow relative to the hallway and six to 12 air exchanges per hour. Patients requiring airborne precautions must be admitted into isolation rooms with negative airflow.
All personnel entering the isolation room must wear an N95 NIOSH rated mask. Staff members must be entered into a facility-wide respiratory protection program and appropriately fit tested to the N95 mask before caring for anyone requiring airborne precautions.
Gloves are required when touching infective material. Gowns are required when caring for a patient with chickenpox (Varicella). Patients must wear a surgical mask during transport when outside the negative flow isolation room.

Droplet Precautions
Droplet precautions are designed to reduce the risk of droplet transmission of infective agents. Droplet transmission involves contact of the conjunctivae or the mucous membranes of the nose or mouth of a susceptible person with large particle droplets. Droplets are generated from the source patient primarily during coughing, sneezing or talking, or during procedures such as suctioning or bronchoscopy.
Transmission of infection by large particle droplets requires close contact between the source patient and the susceptible host. Droplets do not remain suspended in the air and generally travel only short distances, usually three feet or less, through the air. Special air handling and ventilation systems are not required to prevent transmission.
A surgical mask must be worn when within three feet of the patient. Gloves are required when touching infective material. A gown is required if soiling is likely. A private room is desirable; however, patients with the same disease may share a room if necessary. The patient should wear a surgical mask during transport.

Contact Precautions
Contact precautions are designed to reduce the risk of transmission of organisms by direct or indirect contact. Direct contact involves skin-to-skin contact and physical transfer of organisms from an infected/colonized source to a susceptible host. The hands of healthcare workers are most often implicated when direct contact transmission is discussed, but direct contact transmission can also occur between two patients. Indirect contact involves contact of a susceptible host with a contaminated intermediate object, usually some inanimate object in the environment. Contact precautions apply to specified patients known or suspected to be infected or colonized with significant organisms that can be transmitted by direct contact, such as methicillin resistant Staphylococcus aureus (MRSA), vancomycin resistant enterococcus (VRE), Clostridium difficile colitis, and respiratory syncytial virus (RSV).
Gloves are required when entering the patient's room. Gowns must be worn when entering the patient's room if contact with the patient, equipment, or furnishings is anticipated. Gowns are also required if the patient has diarrhea, ileostomy or colostomy.
A private room is required. The patient should be transported only when necessary for diagnosis or treatment, and the risk of infection transmission must be weighed against the need for transport. The patient should wear a clean long sleeved gown if transport is necessary.

Empiric Precautions
The risk of nosocomial transmission of infections is highest before a diagnosis is made and before precautions based on diagnosis can be implemented. The following conditions and syndromes carry a sufficiently high risk of transmission that empiric precautions are warranted until a definitive diagnosis can be confirmed.

1. Acute diarrhea with a likely infectious cause in an incontinent or diapered patient, or diarrhea in an adult with a history of recent antibiotic use, requires contact precautions. Potential pathogens include enteric pathogens or Clostridium difficile.
2. Meningitis requires droplet precautions. Potential pathogens include Neisseria meningitidis.
3. Rash or exanthems that are generalized with unknown etiology including:
   (a) Petechial/ecchymotic rash with fever requires droplet precautions; potential pathogens include Neisseria meningitidis;
   (b) Vesicular rashes require airborne and contact precautions; potential infection is Varicella;
   (c) Maculopapular rash with coryza and fever requires airborne precautions; potential infection is measles (Rubeola).
4. Respiratory infections in an HIV positive patient with cough/fever/upper lobe pulmonary infiltrate require airborne precautions. The potential infection is TB.
5. Respiratory infection in an HIV negative patient or a patient at low risk for HIV infection with cough/fever/pulmonary infiltrate in any lung location requires airborne precautions. The potential infection is TB.
6. Paroxysmal or severe persistent cough during periods of pertussis activity requires droplet precautions. Potential infection is Bordetella pertussis (whooping cough).
7. Respiratory infections, particularly bronchiolitis and croup, in infants and young children require contact precautions. The potential pathogens include respiratory syncytial (RSV) or parainfluenza virus.
8. Risk of multi-drug-resistant microorganisms; history of infection or colonization with multi-drug-resistant organisms; or skin, wound, or urinary tract infection in a patient with a recent hospital or nursing home stay in a facility where multi-drug-resistant organisms are prevalent requires contact precautions. Potential pathogens include multiply antibiotic resistant bacteria.
9. Skin or wound infection, abscess or draining wound that cannot be covered or where the drainage cannot be contained in a dressing requires contact precautions. Potential pathogens include Staphylococcus aureus or Group A streptococcus.

Table 5 lists the clinical conditions that warrant empiric precautions pending confirmation of diagnosis.

Clinical Syndromes or Conditions Warranting Additional Empiric Precautions to Prevent Transmission of Epidemiologically Important Pathogens Pending Confirmation of Diagnosis*

Diarrhea

Skin, wound, or urinary tract infection in a patient with a recent hospital or nursing home stay in a facility where multidrug-resistant organisms are prevalent

* Infection control professionals are encouraged to modify or adapt this table according to local conditions. To ensure that appropriate empiric precautions are implemented always, hospitals must have systems in place to evaluate patients routinely according to these criteria as part of their preadmission and admission care.

† Patients with the syndromes or conditions listed below may present with atypical signs or symptoms (eg, pertussis in neonates and adults may not have paroxysmal or severe cough). The clinician's index of suspicion should be guided by the prevalence of specific conditions in the community, as well as clinical judgment.

‡ The organisms listed under the column "Potential Pathogens" are not intended to represent the complete, or even most likely, diagnoses, but rather possible etiologic agents that require additional precautions beyond Standard Precautions until they can be ruled out.

§ These pathogens include enterohemorrhagic Escherichia coli O157:H7, Shigella, hepatitis A, and rotavirus.

||Resistant bacteria judged by the infection control program, based on current state, regional, or national recommendations, to be of special clinical or epidemiological significance.

From the Public Health Service, US Department of Health and Human Services, Centers for Disease Control and Prevention, Atlanta, Georgia. See Garner JS, Hospital Infection Control Practices Advisory Committee. Guideline for isolation precautions in hospitals. Infect Control Hosp Epidemiol 1996;17:53-80, and Am J Infect Control 1996;24:24-52.

Patient Placement
Patient placement is significant for appropriate precautions. A private room is important to prevent direct or indirect contact transmission when the source patient has poor hygienic habits, contaminates the environment or cannot be expected to assist in maintaining infection control precautions to limit transmission of organisms. When a private room is not available, an infected patient is placed with an appropriate roommate. A private room with appropriate air handling and ventilation is important for reducing the risk of transmission of organisms from a source patient and other persons in the hospital when the organism is spread by airborne transmission.

Transportation of Infected Patients
Limiting the movement and transportation of patients infected or colonized with virulent or epidemiologically important organisms reduces opportunities for transmission of organisms. Such patients should be transported only when essential for care.

Specific Infections

Bloodborne Infections

Hepatitis B. Hepatitis B (HBV), formerly known as serum hepatitis, is more contagious than HIV and every bit as deadly for an unlucky few. Hepatitis B is a widespread inflammatory condition of the liver usually manifested by jaundice and often liver enlargement. Other signs and symptoms include fatigue, vague abdominal pain, loss of appetite, and intermittent nausea and vomiting. There are about 128,000 new cases of Hepatitis B in the United States every year. It is estimated that 1-1.25 million Americans are chronically infected.
Sexual exposure, perinatal exposure or occupational contact with infected blood and body fluids transmits Hepatitis B. The virus can live up to two weeks on inadequately cleaned environmental surfaces; therefore, transmission is possible from objects such as razors, toothbrushes, ear-piercing needles and other items contaminated by blood or infectious body fluids of someone with infection. Up to 40% of infected people do not know how or when they were exposed to the virus.
Vaccination against Hepatitis B is a safe and effective method to prevent infection. The HBV vaccine has been available since 1982. In addition to the Hepatitis B vaccine, Hepatitis B immune globulin (HBIG) is available to provide temporary passive protection following a documented HBV exposure in an unvaccinated person. HBIG is a preparation of immunoglobulin containing high levels of HBV antibody. When given as a combination treatment with the hepatitis B vaccine, it is over 90% effective in preventing disease.

Hepatitis C. Hepatitis C (HCV), formerly known as Hepatitis Non A-Non B (NANB), is the most common chronic bloodborne infection in the United States. Most people with Hepatitis C are chronically infected but might not be aware of their infection because they are not clinically ill. Clinical illness is similar to other types of hepatitis, presenting with jaundice and flu-like symptoms such as fatigue, vague abdominal pain, loss of appetite, and intermittent nausea and vomiting. Serologic testing is necessary to determine the specific hepatitis virus causing illness. Hepatitis C currently causes between 36,000 and 40,000 infections each year, with only about 20% of these infections being symptomatic. Chronic Hepatitis C infection develops in most infected people (75-80%) and chronic liver disease develops in 70% of people diagnosed with Hepatitis C. It is estimated that 3.9 million Americans have been infected with the Hepatitis C virus, of whom about 2.7 million are chronically infected.
Hepatitis C is transmitted in the same manner as Hepatitis B, although sexual contact is a less likely method of transmission. Screening blood, organ and tissue donors; counseling to reduce and/or modify high-risk practices; and compliance with the procedures outlined in standard precautions offer the best protection against Hepatitis C.
Information for education of patients who test positive for HCV is given in Table 6.

Education for Patients with Positive HCV Test Results

Persons who test positive should be provided with information regarding the need for a) preventing further harm to their liver; b) reducing risks for transmitting HCV to others; and c) medical evaluation for chronic liver disease and possible treatment.

To protect their liver from further harm, HCV- positive persons should be advised to

• not drink alcohol;
• not start any new medicines, including over-the-counter and herbal medicines, without checking with their doctor; and
• get vaccinated against hepatitis A if liver disease is found to be present.

To reduce the risk for transmission to others, HCV-positive persons should be advised to

• not donate blood, body organs, other tissue, or semen;
• not share toothbrushes, dental appliances, razors, or other personal-care articles that might have blood on them; and
• cover cuts and sores on the skin to keep from spreading infectious blood or secretions.

HCV-positive persons with one long-term steady sex partner do not need to change their sexual practices. They should

• discuss the risk, which is low but not absent, with their partner (if they want to lower the limited chance of spreading HCV to their partner, they might decide to use barrier precautions [e.g., latex condoms]); and
• discuss with their partner the need for counseling and testing.

HCV-positive women do not need to avoid pregnancy or breast feeding. Potential, expectant, and new parents should be advised that

• approximately 5 out of every 100 infants born to HCV-infected women become infected (this occurs at the time of birth, and no treatment exists that can prevent this from happening);
• infants infected with HCV at the time of birth seem to do very well in the first years of life (more studies are needed to determine if these infants will be affected by the infection as they grow older);
• no evidence exists that mode of delivery is related to transmission; therefore, determining the need for cesarean delivery versus vaginal delivery should not be made on the basis of HCV infection status;
• limited data regarding breast-feeding indicate that it does not transmit HCV, although HCV-positive mothers should consider abstaining from breast feeding if their nipples are cracked or bleeding;
• infants born to HCV-positive women should be tested for HCV infection and if positive, evaluated for the presence or development of chronic liver disease;
• if an HCV-positive woman has given birth to any children after the woman became infected with HCV, she should consider having the children tested.

Other counseling messages

• HCV is not spread by sneezing, hugging, coughing, food or water, sharing eating utensils or drinking glasses, or casual contact.
• Persons should not be excluded from work, school, play, childcare or other settings on the basis of their HCV infection status.
• Involvement with a support group might help patients cope with hepatitis C.

HCV-positive persons should be evaluated (by referral or consultation, if appropriate) for presence or development of chronic liver disease including

• assessment for biochemical evidence of chronic liver disease;
• assessment for severity of disease and possible treatment according to current practice guidelines in consultation with, or by referral to, a specialist knowledgeable in this area
• determination of need for hepatitis A vaccination.

Hepatitis D. Hepatitis D infection (HDV) can be acquired either as a co-infection with HBV or as a superinfection of persons with chronic HBV infection. The modes of HDV transmission are similar to those for HBV, with percutaneous exposures the most efficient. Sexual transmission of HDV is less efficient than for HBV; perinatal HDV transmission is rare. Persons with HBV-HDV co-infection may have more severe acute disease and a higher risk of fulminant hepatitis (2%-20%) compared with those infected with HBV alone; however, chronic HBV infection appears to occur less frequently in persons with HBV-HDV co-infection. Chronic HBV carriers who acquire HDV superinfection usually develop chronic HDV infection. In long-term studies of chronic HBV carriers with HDV superinfection, 70%-80% have developed evidence of chronic liver diseases with cirrhosis, compared with 15%-30% of patients with chronic HBV infection alone. Because HDV is dependent on HBV for replication, HBV-HDV co-infection can be prevented with either pre- or postexposure prophylaxis for HBV. Prevention of HDV superinfection depends primarily on education to reduce risk behaviors.

Human Immunodeficiency Virus (HIV) Infection. HIV infection resulting in Acquired Immunodeficiency Syndrome, AIDS, is a severe life-threatening clinical condition first recognized in 1981. As of December 2000, the cumulative number of AIDS cases reported to the CDC was 774,467. Through the same time period, 8,908 AIDS cases were reported in children under age 13. Total deaths of persons reported with AIDS were 448,060. Estimates suggest that as many as 900,000 Americans are living with HIV and at least 40,000 new infections occur each year. The most recent information from the CDC (December 2000) indicates that both the incidence and death rate from AIDS continue to decline in the United States, but the rates of decline have been leveling since 1998. The greatest percentage of AIDS cases have been drawn from men who have sex with men, and men and women of the injecting drug communities. However, there has been a striking increase in the number of Americans in their teens and early 20s infected heterosexually with HIV, even as rates of infection are declining among those in their late 20s and older. Women ages 18-27 are far more likely to be infected with the virus than their older counterparts. This is particularly true for black women. Though the overall rate of HIV infections among men and women aged 16 to 21 is dropping, women in that age group are now being infected at a rate 50 percent higher than men are. Sexual exposure, perinatal exposure, and occupational contact with infected blood and body fluids transmit HIV.
Within a few weeks to months after contracting HIV, many people develop a mononucleosis-like illness lasting for a week or two. Infected people may then be without clinical symptoms for months or years before clinical symptoms, including opportunistic infections, appear. Onset of clinical illness is usually insidious with nonspecific symptoms such as lymphadenopathy, anorexia, weight loss, chronic diarrhea, fever, and fatigue. The severity of HIV-related opportunistic infections is generally related to the degree of immune dysfunction. To date, the CDC is aware of 56 healthcare workers in the United States who have documented HIV seroconversion following occupational exposures; 25 of these have developed AIDS. A documented exposure means the person tested negative to HIV around the time of the exposure but tested positive within one year of the exposure. Another 138 HIV-infected healthcare workers are classified as having possible cases of occupational transmission. These persons have a history of occupational exposure to blood and other potentially infectious body fluids and no other risk factors for HIV infection, but do not have a documented seroconversion following the occupational exposure. Nurses are the largest occupational group represented, with 23 of the 56 documented conversions. The most frequent exposures (86%) were through percutaneous injury, including needle sticks.
The primary method of preventing occupational exposure to HIV and other bloodborne pathogens is to follow infection control precautions identified in the Standard (Universal) Precautions. Healthcare workers must assume that all blood and body fluids from all patients are potentially infectious. Safety devices have also been developed to help prevent needle-stick injuries if used properly. Further strategies are being developed to reduce the risk of injury associated with sharps disposal.
Although the most important approach toward reducing the risk of occupational exposure to HIV transmission is to prevent occupational exposures, there should be plans for post exposure management for healthcare workers. CDC has issued guidelines for the management of these exposures to HIV and recommendations for Post-Exposure Prophylaxis (PEP). Check with your facility employee health or infection control staff to learn the policies in place at your institution.

Tuberculosis
From the 1960's until the last half of the 1980's it was generally thought that tuberculosis (TB) would be eliminated from the United States. There had been an annual 5% decline in the number of TB cases since the 1950's, and a 6-7% annual decline in cases between 1981 and 1984; and U.S. public health officials hoped to eradicate TB completely by the year 2010. However, in 1985 the number of TB cases began to increase; between 1985 and 1991 there was an 18% increase in the overall number of reported cases. The CDC identified two important reasons for the resurgence of TB in the United States: the HIV/AIDS epidemic, and the emergence of multi-drug resistant TB (MDR-TB).
In the year 2000, a total of 12,942 cases of TB were reported to the CDC from the 50 states and the District of Columbia. This represented a 22% decrease from 1999 cases and almost a 50% decrease from 1992, when the number of cases peaked during the resurgence of TB in the United States. In addition, levels of isoniazid resistance have been relatively stable and the number and proportion of MDR-TB cases have decreased since 1993, when the CDC began monitoring anti-TB drug resistance through the national TB surveillance system.
This decline in the number of cases is attributed to stronger TB control programs that emphasize promptly identifying persons with TB, initiating appropriate therapy and ensuring completion of therapy.

Mycobacterium Tuberculosis (MTB) Infection. Tuberculosis is caused by Mycobacterium tuberculosis (MTB), a slow growing, acid-fast aerobic bacillus. It is spread through airborne particles, or droplet nuclei generated when persons who have pulmonary or laryngeal TB sneeze, cough, speak or sing. Droplet nuclei are very small, from 1-5 microns in diameter, and they can remain suspended in the air for several hours. This means that TB can move very quickly through crowded communities where persons share the same air space such as hospitals, prisons, or living quarters. TB is generally not transmitted through contact with environmental surfaces or the personal items of an infected person.
Infection occurs when a susceptible person inhales droplet nuclei containing MTB. These inhaled droplet nuclei are small enough to reach the alveoli of the lungs where the MTB is taken up by alveolar macrophages and spread throughout the body. The immune system limits multiplication and spread of the tubercle bacilli; however, some organisms remain dormant and viable for many years. This condition is referred to as a latent TB infection. Persons with latent infection usually have a positive TB skin test but do not have symptoms of active TB and are not infectious.
The probability that a person will become infected depends on the concentration of the droplet nuclei and the duration of exposure. An important note is that most persons who inhale the bacteria do not become infected; of those who do, many do not develop active disease.
Persons who do develop active disease usually do so in the first two years following infection. In general, there is a 10% risk of developing active disease over the course of a lifetime. Persons with latent infection that become infected with HIV have approximately an 8%-10% risk of developing active infection each year. HIV-infected people who are already immunocompromised when they become newly infected with MTB have an even greater risk of developing active TB.
As latent infection progresses to active disease, the person begins to display signs and symptoms including lethargy, fever, night sweats and weight loss. Weight loss is the primary reason the disease was once called "consumption." The person with active infection often develops a productive cough with blood-tinged sputum as the disease progresses. Chest pains and shortness of breath are common as the lungs become ravaged. If a lung cavity erodes an artery, the person may experience massive hemorrhage.

Tuberculosis Transmission and Control. Transmission of M. tuberculosis is a recognized risk to patients and workers in healthcare facilities. Transmission is most likely to occur from patients who have unrecognized pulmonary or laryngeal TB, who are not on effective anti-TB therapy, and have not been placed in TB isolation. Several recent TB outbreaks in healthcare facilities, including outbreaks of MDR-TB, have heightened concern about nosocomial transmission. Patients who have MDR-TB can remain infectious for prolonged periods, which increases the risk for nosocomial and/or occupational transmission of M. tuberculosis. Increases in the incidence of TB have been observed in some geographic areas; these increases are related partially to the high risk for TB among immunosuppressed persons, particularly those infected with HIV. Transmission of M. tuberculosis to HIV-infected persons is of particular concern because these persons are at high risk for developing active TB if they become infected with the bacteria. Thus, healthcare facilities should be particularly alert to the need for preventing transmission of M. tuberculosis in settings in which HIV-infected persons work or receive care.
The CDC is the Public Health Service agency responsible for providing direction and leadership in the prevention and control of communicable diseases and other preventable conditions. Late in 1994, the CDC published its infection control strategies designed to prevent the transmission of TB in healthcare facilities. Although the CDC cannot enforce regulations related to infection control practice, its guidelines and recommendations have become standards for governmental regulations and legislation. In 1994 the Occupational Safety and Health Administration (OSHA) mandated TB protection using CDC guidelines; however, OSHA has still not published a final TB control standard. OSHA currently enforces TB standards using their general duty clause.
Recently, nosocomial TB outbreaks have demonstrated the substantial morbidity and mortality among patients and healthcare workers that have been associated with incomplete implementation of CDC's Guidelines for Preventing the Transmission of Tuberculosis in Health-Care Facilities, with Special Focus on HlV-Related Issues. The prevention of TB infection in all healthcare settings requires healthcare workers to use appropriate infection control and isolation procedures. Although completely eliminating the risk for transmission of M. tuberculosis in all healthcare facilities is not possible, adherence to these guidelines should reduce the risk to persons in these settings.

Tuberculosis Control Recommendations. An effective TB infection control program requires early identification, isolation, and treatment of persons who have active TB. The primary emphasis of TB infection control plans in healthcare facilities should be on achieving the following goals by the application of a hierarchy of control measures, including (1) the use of administrative measures to reduce the risk for exposure to persons who have infectious TB, (2) the use of engineering controls to prevent the spread and reduce the concentration of infectious droplet nuclei, and (3) the use of personal respiratory protective equipment in areas where there is still a risk for exposure to M. tuberculosis (e.g., TB isolation rooms). Table 7 illustrates the characteristics of an effective TB control program.

Characteristics of an Effective Tuberculosis (TB) Infection Control Program*

*A program such as this is appropriate for healthcare facilities in which there is a high risk for transmission of Mycobacterium tuberculosis.

I. Assignment of responsibility

A. Assign responsibility for the TB infection-control program to qualified person(s).
B. Ensure that persons with expertise in infection control, occupational health, and engineering are identified and included.

II. Risk assessment, TB infection-control plan, and periodic reassessment

A. Initial risk assessment

1. Obtain information concerning TB in the community.
2. Evaluate data concerning TB patients in the facility.
3. Evaluate data concerning purified protein derivative (PPD)-tuberculin skin-test conversions among healthcare workers in the facility.
4. Rule out evidence of person-to-person transmission.

B. Written TB infection-control program

1. Select initial risk protocol(s).
2. Develop written TB infection-control protocols.

C. Repeat risk assessment at appropriate intervals

1. Review current community and facility surveillance data and PPD-tuberculin skin-test results.
2. Review records of TB patients.
3. Observe worker infection-control practices.
4. Evaluate maintenance of engineering controls.

III. Identification, evaluation, and treatment of patients who have TB

A. Screen patients for signs and symptoms of active TB:

1. On initial encounter in emergency department or ambulatory-care setting.
2. Before or at the time of admission.

B. Perform radiological and bacteriological evaluation of patients who have signs/symptoms of TB.
C. Promptly initiate treatment.

IV. Managing outpatients who have possible infectious TB

A. Promptly initiate TB precautions.
B. Place patients in separate waiting areas or TB isolation rooms.
C. Give patients a surgical mask, a box of tissues, and instructions regarding the use of these items.

V. Managing inpatients who have possible infectious TB

A. Promptly isolate patients who have suspected or known infectious TB.
B. Monitor the response to treatment.
C. Follow appropriate criteria for discontinuing isolation.

VI. Engineering recommendations

A. Design local exhaust and general ventilation in collaboration with persons who have expertise in ventilation engineering.
B. Use a single-pass air system or air recirculation after high-efficiency particulate air (HEPA) filtration in areas where infectious TB patients receive care.
C. Use additional measures, if needed, in areas where TB patients may receive care.
D. Design TB isolation rooms in healthcare facilities to achieve >6 air exchanges per hour (ACH) for existing facilities and >12 ACH for new or renovated facilities.
E. Regularly monitor and maintain engineering controls.
F. TB isolation rooms that are being used should be monitored daily to ensure they maintain negative pressure relative to the hallway and all surrounding areas.
G. Exhaust TB isolation room air to outside or, if absolutely unavoidable, re-circulate after HEPA filtration.

VII. Respiratory protection

A. Respiratory protective devices should meet recommended performance criteria.
B. Respiratory protection should be used by persons entering rooms in which patients with known or suspected infectious TB are being isolated, by healthcare workers when performing cough-inducing or aerosol-generating procedures on such patients, and by persons in other settings where administrative and engineering controls are not likely to protect them from inhaling infectious airborne droplet nuclei.
C. A respiratory protection program is required at all facilities in which respiratory protection is used.

VIII. Cough-inducing procedures

A. Do not perform such procedures unless absolutely necessary.
B. Perform such procedures in areas that have local exhaust ventilation devices (e.g., booths or special enclosures) or, if this is not feasible, in a room that meets the ventilation requirements for TB isolation.
C. After completion of the procedure, TB patients should remain in the booth or special enclosure until coughing subsides.

IX. Healthcare worker TB training and education

A. All healthcare workers should receive periodic TB education appropriate for their work responsibilities and duties.
B. Training should include the epidemiology of TB in the facility.
C. TB education should emphasize concepts of the pathogenesis of and occupational risk of acquiring TB.
D. Training should describe work practices that reduce the likelihood of transmitting TB.

X. Healthcare worker counseling and screening

A. Counsel all healthcare workers regarding TB and TB infection.
B. Counsel all workers about the increased risk to immunocompromised persons for developing active TB.
C. Perform PPD skin tests on workers at the beginning of their employment, and repeat PPD tests at periodic intervals.
D. Evaluate symptomatic workers for active TB.

XI. Evaluate healthcare worker PPD test conversions and possible nosocomial transmission of TB

XII. Coordinate efforts with public health department(s)

Source: CDC, 1994

Administrative measures reduce the risk of exposing uninfected persons to persons who may transmit TB. These measures include (1) development and implementation of effective policies and procedures to ensure rapid identification, isolation, diagnosis and treatment of persons likely to have TB; (2) implementation of effective work practice controls such as wearing appropriate respiratory protection and keeping the doors to isolation rooms closed; (3) educating and training personnel about TB; and (4) screening healthcare workers for TB infection and active disease.
Engineering controls prevent the spread or reduce the concentration of infectious droplet nuclei in the environment. These controls include directional airflow, local exhaust ventilation and use of ultraviolet germicidal irradiation (UVGI).
Personal respiratory protection is the third level of protection and is intended for use in situations where there is increased risk of infection with MTB.

TB Respiratory Protection. Personal respiratory protection should be used by: a) persons entering rooms in which patients with known or suspected infectious TB are being isolated; b) persons present during cough-inducing or aerosol-generating procedures performed on such patients, and c) persons in other settings where administrative and engineering controls are not likely to protect them from inhaling infectious airborne droplet nuclei. These other settings include transporting patients who may have infectious TB in emergency transport vehicles and providing urgent surgical or dental care to patients who may have infectious TB before a determination has been made that the patient is noninfectious.
Respiratory protection devices must be classified as a National Institute of Occupational Safety and Health (NIOSH) approved N95 filtering face mask. The healthcare worker must be fit-tested prior to use of the TB N95 Mask. In some settings, workers may be at risk for two types of exposure: inhalation of MTB and mucous membrane exposure to fluids that may contain bloodborne pathogens. In these settings, protection against both types of exposure should be used.

Environmental Disinfection and Sterilization Requirements. Environmental surfaces are seldom associated with the transmission of TB infection. Therefore, it is not necessary for you to make extraordinary attempts to sterilize or disinfect surfaces. There is no requirement for food trays or utensils of TB-infected persons to be handled differently than those from other clients.

Screening. The OSHA draft TB standard requires healthcare workers to be skin tested for tuberculosis on a recurring and routine basis. The frequency of testing should be determined by the likelihood of exposure to infectious TB. Each facility should conduct an initial and periodic reassessment of TB risk. This risk assessment should be used to determine the frequency of skin testing. Different areas of the facility may require different frequency of testing depending on the type of clients served and the procedures performed.

The Prion Diseases: Creutzfeldt- Jakob (CJD) and Mad Cow Disease (BSE)
Creutzfeldt-Jakob disease (CJD) is a rapidly progressive, invariably fatal neurodegenerative disorder believed to be caused by an abnormal isoform of a cellular glycoprotein known as the prion protein. CJD is classified as a transmissible spongiform encephalopathy (TSE) along with other prion diseases that occur in humans and animals. CJD occurs worldwide and the estimated annual incidence in many countries, including the United States, has been reported to be about one case per million population.
The vast majority of CJD patients die within one year of illness onset. In about 85% of patients, CJD occurs as a sporadic disease with no recognizable pattern of transmission. A smaller proportion of patients (5 to 15%) develop CJD because of inherited mutations of the prion protein gene. These inherited forms include Gerstmann-Straussler-Scheinker syndrome and fatal familial insomnia.
Since 1996, evidence has been increasing for a causal relationship between ongoing outbreaks in Europe of a TSE disease in cattle, called bovine spongiform encephalopathy (BSE, or "mad cow disease"), and a disease in humans, called new variant Creutzfeldt-Jakob disease (nvCJD). Both disorders are invariably fatal brain diseases with unusually long incubation periods measured in years, and are apparently caused by prions as well.
Iatrogenic transmission of the CJD agent has been reported in over 250 patients worldwide. These cases have been linked to the use of contaminated human growth hormone, dura mater and corneal grafts, or neurosurgical equipment. Of the six cases linked to the use of contaminated equipment, four were associated with neurosurgical instruments, and two with stereotactic EEG depth electrodes. No iatrogenic CJD cases associated with exposure to the CJD agent from surfaces such as floors, walls, or countertops have been identified.
Destruction of all heat-resistant surgical instruments that come in contact with high infectivity tissues (brain, spinal cord, and eyes), albeit the safest and most unambiguous method of infection control, may not be practical or cost effective. The stringent sterilization methods described below should be used to reprocess medical instruments that come in contact with high infectivity tissues of persons with diagnosed CJD or those known to be blood relatives of patients with inheritable forms of TSEs.

1. Immerse in 1N sodium hydroxide (NaOH) and heat in a gravity displacement autoclave at 121 C for 30 min; clean; rinse in water; and subject to routine sterilization. [CDC NOTE: On August 30, 2001, CDC was notified by a laboratory-equipment manufacturer about a concern that this sterilization procedure might produce a reaction which could be both harmful to human health and damaging to the autoclave. CDC is currently consulting with CJD and equipment-sterilization experts to assess the concern reported by the manufacturer. Persons who use this procedure should be cautious in handling hot sodium hydroxide solution (post autoclave) or potential exposure to gaseous sodium hydroxide, exercise caution during all sterilization steps, and allow the autoclave, instruments, and solutions to cool down before removal.]
2. Immerse in 1N NaOH or sodium hypochlorite (20,000 ppm) for 1 hour; transfer instruments to water; heat in a gravity displacement autoclave at 121 C for 1 hour; clean; and subject to routine sterilization.
3. Immerse in 1N NaOH or sodium hypochlorite (20,000 ppm) for 1 hour; remove and rinse in water, then transfer to open pan and heat in a gravity displacement (121 C) or porous load (134 C) autoclave for 1 hour; clean; and subject to routine sterilization.

All disposable instruments, materials, and wastes that come in contact with high infectivity tissues (brain, spinal cord, and eyes) and low infectivity tissues (cerebrospinal fluid, kidneys, liver, lungs, lymph nodes, spleen, and placenta) of suspected or confirmed TSE patients should be disposed of by incineration. Surfaces and heat-sensitive re-usable instruments that come in contact with high infectivity and low infectivity tissues should be decontaminated by flooding with or soaking in 2N NaOH or undiluted sodium hypochlorite for 1 hour and rinsed with water.
In some patients undergoing neurosurgery, a CJD diagnosis that is not suspected before the procedure may be confirmed after the surgery. For this group of patients, in whom the clinical diagnosis leading to the neurosurgical procedure remains unclear, the instruments should be reprocessed in the same manner as that described for instruments used in procedures involving suspected or confirmed CJD patients. Unless a clear non-CJD diagnosis is established, these patients should be considered as CJD patients for all other infection control requirements.

Multiple Drug Resistant Organisms
Bacteria, like most other living organisms, adapt to their environment; and part of the bacteria's adaptation has lead to the development of resistance to antibiotics. Antibiotics were introduced into medicine in the late 1940s, and antibiotic resistance soon followed. A penicillinase-producing Staphylococcus aureus (S. aureus) first appeared in the 1950s, Methicillin-resistant S. aureus (MRSA) in the 1960s, gram-negative bacilli resistant to aminoglycosides (gentamicin, tobramycin) in the 1970s, MRSA resistance to fluoroquinolones in the 1980s, and vancomycin resistance among enterococci in the 1990s. Unfortunately, resistant organisms continue to appear, with the most recent organism identified as VISA: S. aureus intermediately resistant to vancomycin, the drug of choice for treating serious MRSA infections. With the arrival of VISA, the appearance of an organism fully resistant to vancomycin is much more likely.
Bacteria possess the ability to develop resistance to antibiotics in various ways. They can mutate, express a latent gene, or acquire new resistance material through direct exchange of DNA with other bacteria. The three major mechanisms of resistance include production of an enzyme that will inactivate or destroy the antibiotic, alteration of the antibiotic target site to prevent action of the antibiotic, or prevention of the antibiotic's access to the target site.
Antibiotic resistance in hospitals may be higher than in the community because hospitalized patients may have more severe illness, may be severely immunocompromised, or may be exposed to newer devices and procedures that increase their risk of infection or colonization with resistant organisms. Introduction of resistant organisms from the community and/or ineffective infection control and isolation practices may result in a large number of resistant organisms present in the environment. Finally, use of broad-spectrum antibiotics and high antibiotic usage within a relatively small geographic area might force the development of resistant organisms.
Current evidence, based on the following observations, suggests that there is a causal relationship between antibiotic usage in some hospitals and antibiotic resistance.

1. Changes in microbial resistance parallel antibiotic usage.
2. Antibiotic resistance is more common in nosocomial bacterial strains.
3. Patients infected with resistant organisms are more likely to have received antibiotics.
4. Areas that have the highest rates of antibiotic resistance also have the highest rates of antibiotic usage.
5. The likelihood that a patient will become colonized with resistant organisms increases with the duration of exposure to antibiotics. For some pathogens, the development of resistance during treatment or prophylaxis is considered a more important risk factor for acquiring resistant organisms than patient-to-patient transmission.

Transmission of Resistant Organisms. Resistant organisms gain entry into a healthcare facility through an infected or colonized patient or healthcare worker. Resistant organisms are transmitted from patient to patient, just as susceptible bacteria are. Resistant bacteria appear just as potent as the susceptible pathogen in animal models. Both enterococci and staphylococcus are part of the body's normal flora and are spread through direct contact between the patient and caregiver or patient-to-patient. Although MRSA has been recovered from environmental surfaces, it is transmitted mainly on healthcare workers' hands.
Colonization can last indefinitely, and there is no single standard for the length of time a patient should remain in isolation. Many institutions require three sets of negative cultures from multiple body sites, obtained at one or more weekly intervals, before removing a patient from isolation precautions. Healthcare workers are generally not cultured for resistant organisms unless implicated in an outbreak. Once identified, moreover, there are no firm guidelines on treatment or work restrictions for healthcare workers infected or colonized with resistant organisms. Each institution will have its own employee guidelines. The following control recommendations are currently in use to prevent the spread of MRSA or VRE. These same techniques can be used to prevent the rise of VISA and other antibiotic resistant organisms.

Control Recommendations. A good prevention program includes an active surveillance system to identify resistant organisms, effective infection control practices to minimize transmission within the institution, and an effective antibiotic-use monitoring program.
Healthcare workers should care for all patients using standard precautions.
Contact precautions should be used for patients colonized or infected with resistant microorganisms. If private rooms are not available, cohorting patients (having patients with the same diagnosis share a room) should be considered.
Hands should be washed with an antimicrobial agent such as povidone iodine, chlorhexidine gluconate, or alcohol-based waterless cleaners.
Gowns should be worn when entering the room if the healthcare worker anticipates his/her clothing will have substantial contact with the patient or his clothing, environmental surfaces, or items in the patient's room; or if the patient is incontinent or has diarrhea, an ileostomy or colostomy, or wound drainage not contained in a dressing. This is especially important with VRE patients.
Gloves should be worn as previously outlined in standard precautions. If the client is incontinent or has diarrhea, change gloves when moving from a "dirty" area of the body to a clean one, especially with VRE patients.
Healthcare workers must be careful not to touch any potentially contaminated surface such as a bed or bed stand after removing the protective gown and gloves. Again, this is especially important when caring for patients colonized or infected with VRE.
Make sure family and friends know why they need to wear protective garb when they visit the patient, and how to put it on, remove it, and dispose of it properly.
Avoid sharing equipment. If equipment is brought into the room, avoid placing it on the bed or bed stand. Clean equipment with an appropriate disinfectant before leaving the room. Be careful not to touch any potentially contaminated surface such as a bed or bed stand after cleaning the equipment.
Medical and ancillary staff responsible for pharmacy decisions should review and ensure that the use of antibiotics is appropriate, and restrict use of specific antibiotics as needed.
Know your institution's policies and procedures for antibiotic use. Instruct your patient that he/she should take his antibiotic for the full prescription period, even if he/she begins to feel better. Make sure you client understands that not all diseases can be treated with antibiotics: for example, antibiotics don't kill viruses.

Environmental Disinfection and Sterilization Requirements. Clearly the environment can be an important reservoir of resistant microorganisms. There is no evidence that multi-drug resistant organisms including VRE are more resistant to routinely used hospital disinfectants than are susceptible organisms. It is important to ensure that routine procedures for cleaning and disinfection of medical devices and environmental surfaces are followed carefully.

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