Document Type


Date of Award

Spring 5-17-2003


College of Science, Engineering, and Technology (COSET)

Degree Name

MS in Biology

First Advisor

Professor Sunday Fadulu


Nosocomial infections have been recognized for over a century as a critical problem affecting the quality of health care and a principal source of adverse health care outcomes. The National Nosocomial Infections Surveillance System defines a nosocomial infection as (1) a localized or systemic condition that results from adverse reaction to the presence of an infectious agent(s) or its toxin(s) and (2) that was not present or incubating at the time a patient is admitted to a hospital. Today, nosocomial infections affect over 2 million patients annually in the United States at a cost in excess of $4.5 billion (Hormaeche, 1992). Among all major complications of hospitalization, nosocomial infections account for over 50% and are responsible for about 20,000 deaths in the U.S. per year (Wilson, 2000). Nosocomial infections are the result of three factors occurring in tandem: high prevalence of pathogens; high prevalence of immunocompromised hosts; efficient mechanisms of transmission. Agents that cause nosocomial infections vary in structure and size from viruses to protozoa. However, bacteria together with some viruses and fungi are of greatest significance as nosocomial infection pathogens. Nosocomial infections are primarily caused by opportunists, particulary by: Enterococcus spp., Escherichia coli, 2 Pseudomonas spp., and Staphylococcus aureus. These organisms become dangerous when they acquire antibiotic resistance factors. Hospitals are viewed today as institutions where scientific advances are used to , provide the most up to date diagnostic and therapeutic services for patients. This optimistic view is tempered, however, by the realization that the hospital also can be a dangerous place for patients (Schaffner, 2002). According to a recent CDC study, more than 50 million of the 150 million antibiotic prescriptions written each year for patients outside of hospitals are unnecessary. Each time a patient takes an antibiotic for a bacterial infection the drug may kill most of the bacteria. However, a few tenacious germs may survive by mutating or acquiring resistance genes from other bacteria. These surviving genes can multiply, quickly creating drug resistant strains. Some commonly used antimicrobials that are not effective with drug resistant bacteria are: Penicillin, Ampicillin, Antipseudomonal and Antistaphylococcal Penicillins, Cephalasporins, Carbapenem, Aztreonam, Fluoroquinolones, Trimethoprim and Vancomycin. A new class of antibiotics known as oxazolidinones were introduced in the United States in April of 2000. These drugs are indicated for treatment of nosocomial infections involving Gram positive organisms that are resistant to many of the drugs listed above. The sites of nosocomial infections in order from most to least common are: urinary tract; surgical wounds; respiratory tract; skin-particularly bums; blood bacteremia; gastrointestinal tract; and central nervous system. These infections are spread from person to person via direct contact, droplet, airborne, fecal-oral and blood borne routes. 3 The interaction of host, microorganism, and environment constitutes the basis for the epidemiology of infectious diseases. When considering nosocomial infections, the interactions among a hospitalized patient or healthcare worker, pathogens, and the hospital environment, including various therapeutic and diagnostic procedures, determine the probability of various nosocomial infections. A number of risk factors have been linked to the development of nosocomial infections, especially the organisms with antibiotic resistant properties. The primary risk factor is prior treatment with antibiotics, especially broad spectrum agents. Surveillance of nosocomial infections can be used to assess the quality of care in a particular hospital. Also, surveillance can indirectly aid in the understanding of the causes of nosocomial infections. The purpose of this project is to evaluate the prevalence of nosocomial infections among patients at the Dental Branch of the University of Texas Health Science Center as well as at the Texas Tech University Medical Center. It is hoped that this research will be able to contribute to the ongoing battle against the pathogenicity of nosocomial infections by shedding light on the biology and biochemical processes that cause their spread, and their prevalence in this particular environment