Epidemiological Studies of Nosocomial Infections withPseudomonas aeruginosaUsing a DNA Probe

A DNA probe encoding the Pseudomonas aeruginosa pilin gene has been developed in the authors' laboratory and has been shown to be a useful epidemiological tool. In the present study this technology, together with other typing methods, has been used to define relatedness and possible transmission routes of P aeruginosa strains isolated in several hospital wards. Clusters of P aeruginosa infections, suspected to be the result of nosocomial transmission, developed in a general intensive care unit (ICU) and a neurosurgical ward/ICU, as well as in a burn unit, were studied using antibiograms, lipopolysaccharide-serotyping, and gene probe analysis. Results of these studies demonstrated that each of the general and neurosurgical ICU isolates were different, making nosocomial transmission very unlikely. However, within the burn unit, patient isolates had identical profiles, suggesting that spread between patients was occurring or that a common source of infection was present. Changes in infection control measures within the unit were introduced and may have contributed to eradication of the outbreak. DNA probe studies were valuable in clarifying epidemiological relatedness of isolates that was not evident with the other typing strategies and identified a possible burn-associated strain.