Nosocomial (hospital-acquired) infections are infections patients acquire while staying in a healthcare facility. They can be the result of many factors, ranging from exposure to contaminated equipment and solutions, to a deficiency in the immune system.
These infections are extremely problematic for the patient. Nosocomial infections lengthen hospital stays 5-10 days, add between $4.5 and $15 billion annually to the cost of healthcare, and result in increased morbidity and mortality among patients.1
Of the 35 million patients admitted to hospitals annually in the United States, about 1.75-3 million acquire a nosocomial infection. In the U.S., nosocomial infections have caused approximately 80,000 deaths per year since the 1970s.2
The clinical microbiology laboratory plays a vital role in the surveillance, investigation and control of healthcare-associated infections.3 Surveillance of nosocomial infections has been based upon the isolation of infectious agents by culture and biochemical identification.
However, it has become increasingly more important to apply molecular biology assays to identify specific DNA and RNA sequences. These newer methods offer more rapid results and provide additional epidemiological information that may help to determine the mode of transmission.
Additionally, the occurrence of multidrug resistant bacteria as causes of nosocomial infections has increased the need for monitoring antimicrobial resistance with rapid tests in an attempt to control these organisms.4
This article will discuss surveillance results of major medical centers, and describe common isolates and sites of infections.
A multicenter study was conducted in Germany with the intention of providing data on the incidence of nosocomial bloodstream infections (BSIs) and pneumonia, particularly in neutropenic patients who had had bone marrow transplants (BMTs) or peripheral blood stem cell transplants (PBSCTs). 5
A total of 1,899 patients qualified for the study. At the conclusion of the study, 395 BSIs and 168 cases of pneumonia had been identified. Following allogenic transplantation, 22.4 percent of patients acquired a BSI, and 11 percent acquired pneumonia. In patients receiving autologous transplantations, it was observed that 18.2 percent acquired a BSI and 5.4 percent developed pneumonia.
Infections were caused by 460 different microorganisms. Of these, 57 percent were coagulase-negative staphylococci, and the remainder included streptococci, Escherichia coli, enterococci, Candida sp. and Staphylococcus aureus (Table 1).
In 71 percent of the cases of pneumonia, no pathogen was isolated. Identified pathogens included Candida sp., coagulase-negative staphylococci, Aspergillus sp. and enterococci.
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