Nosocomial infections are defined as infections that are neither present nor incubating at the time of hospital admission.
Nosocomial infections range from mild to severe, depending on the affected system and resistance of the bacteria. On average,
human nosocomial infections result in a 2.5 times longer length of stay in hospital. In veterinary medicine, prolonged hospital
stays can grossly affect patient outcome due to cost limitations, which can result in euthanasia if owners cannot afford to
pay for the extended hospitalization and antimicrobial treatment. Universal key points for infections control include hand
washing and disinfectant protocols.
Nosocomial infections can also arise from endogenous or exogenous sources. Endogenous sources imply self-infection with a
patient's own overgrowth of bacterial flora, typically as a result of the use of broad spectrum antimicrobials affecting an
otherwise normal balance in the patient's normal flora. Use of the broad-spectrum antibiotics may allow more resistant bacteria
to survive and proliferate, while more susceptible organisms diminish. Exogenous sources are typically from outside sources,
such as the use of contaminated equipment or devices, non-sterile technique in invasive procedures, or introduced from the
hands of the veterinary staff onto the patient through an open wound, incision, or handling of tubes or catheters inserted
into the patient. Bacteria that are most often associated with nosocomial infections include: Enterococcus spp., E. coli,
Staphylococcus spp., Enterobacter spp., Klebsiella spp., Acinetobacter spp., and Pseudomonas spp. Nosocomial infections can
present in many sites. The most common nosocomial infections reported in medical literature includes urinary tract infections,
bloodstream infections, surgical site infections, infections of the respiratory and gastrointestinal tract.
In the critical care setting, a high rate of infection can be common due to organisms present, multiple invasive procedures
and devices used, numerous care members and the type of underlying disease process present in the patient. The risk of infection
increases with the patient's age, and the use of immunosuppressant drugs (such as steroids or chemotherapy agents). Other
factors that influence a host's ability or defense against infection include: leukopenia, decreased granulocyte function,
burns, presence of a concurrent infection, severe underlying illness, and age (very young or geriatric patients).
The hospital environment contributes negligibly to the acquisition and spread of most nosocomial infections. Therapeutics
are directed towards monitoring and preventing nosocomial infections through mandatory hospital and patient care protocols.
Environmental culturing in order to identify causative organisms should also be performed several times a year in heavy treatment
and patient recovery areas.