People may become infected through exposure to infected patients if proper precautions are not used or acquire infection outside the hospital. They may then transmit the infection to susceptible patients, members of their households, or other community contacts.

Here we need to focus on diseases that are of particular concern to health workers because of the possibility of transmission.

One of the common infections to discuss is diarrhea, specifically acute diarrhea.

Various agents may cause diarrhea in patients and hospital personnel. Salmonella, Shigella, and Campylobacter species are among the common bacterial enteric pathogens.

Infection with these agents may produce mild symptoms but is often accompanied by other symptoms, such as abdominal cramps, fever or bloody diarrhea.

Diarrheal illness accompanied by such symptoms suggests a bacterial cause. Giardia lamblia and other protozoa are also frequent causes of diarrhea. Any of these agents may be nosocomially transmitted via the hands of personnel who are infected.

If personnel contract an acute diarrheal illness accompanied by fever, cramps or bloody stools, they are likely to be excreting potentially infective organisms in their feces. The specific cause of acute diarrhea, however, cannot be determined solely on the basis of clinical symptoms; thus, appropriate laboratory tests are important. Not allowing these persons to take care of patients pending evaluation will prevent transmission.

Evaluation of personnel may usually be limited to an initial culture for bacterial pathogens and stool examination for intestinal protozoa; repeat studies may be indicated if the results of the first tests are negative and the illness persists.

Viral hepatitis has long been recognized as a nosocomial hazard. The agents that most commonly cause this viral hepatitis are hepatitis A virus (HAV), hepatitis B virus (HBV), and Hepatitis C.

Needle-stick injuries account for a large number of the work-related accidents reported in health care facilities.

Most injuries happen on patient-care units when health care workers are disposing of used needles, administering parenteral injections or infusion therapy especially to uncooperative patients, drawing blood, recapping needles after use, handling linens or trash containing uncapped needles, and cleaning up after patient-care procedures in which needles are used.

The risk of needle-stick injuries can be reduced by discarding used needles in puncture-resistant disposal units without first recapping them or purposely bending or breaking them by hand. Risk of injury may also be reduced if personnel obtain assistance when administering injections or infusion therapy to uncooperative patients and if personnel use caution when cleaning up after procedures that include the use of needles.

 Additionally, the incidence of needle stick injuries may be reduced by providing needle-disposal units throughout the hospital in locations that facilitate their immediate use for example in nursing stations, patient rooms, laboratories, and utility rooms.

Staphylococcal aureus is a skin bacterial infection that occurs frequently in humans. In nosocomial transmission, there are two sources: a person with a lesion or an asymptomatic carrier. Persons with skin lesions due to S. aureus are most likely to disseminate these organisms.

Direct contact is the major route of transmission. Even a single boil in an occult body site for example the axilla caused by S. aureus may increase the likelihood of dissemination. One way to decrease the possibility of dissemination is to not allow patient-care personnel to work until skin infection caused by this organism is resolved.

Some people especially young children may be exposed to patients with cytomegalovirus (CMV) infection, but the risk of acquiring CMV infection from patients appears to be small.

There are two principal reservoirs of CMV in the hospital; from infants infected with CMV and immunocompromised patients such as cancer patients and those undergoing kidney or bone marrow transplant.

The precise mechanism of transmission is unknown; however, infection appears to be acquired only through intimate, direct contact with an excreter of CMV or contact with contaminated secretions. Virus can be shed in the urine, saliva, respiratory secretions, tears, feces, breast milk, semen, and cervical secretions.

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