GENOTYPIC INVESTIGATION OF MULTIDRUG-RESISTANT ACINETOBACTER-BAUMANNII INFECTIONS IN A MEDICAL INTENSIVE-CARE UNIT

Multi-resistant Acinetobacter baumannii isolates obtained from 13 hosp italized patients over a six-month period were evaluated. One patient had an isolate susceptible only to imipenem; the next three had isolat es susceptible to imipenem and ampicillin/sulbactam; the next six pati ents had isolates which were susceptible to imipenem, amikacin, and am picillin/sulbactam; while the final three patients had isolates which were susceptible to imipenem and ampicillin/sulbactam. Ten patients di ed, five within 10 days of a positive culture. Five of six patients wi th bacteraemia succumbed to the infection. DNA extracted from all isol ates was amplified by polymerase chain reaction using four random prim ers (RAPD). The resulting band patterns were compared and strains iden tified. In addition, all isolates were biotyped. RAPD analysis and bio typing showed that there were two distinct strains involved. The first four patients were infected with one strain (genotype 'A', biotype 9) , the subsequent nine patients were infected with a second strain (gen otype 'B', biotype 1). These results suggested that there was patient- to-patient spread of strains. Institution of, and strict adherence to, isolation procedure and other infection control practices controlled the spread of infection. These data emphasize the need for active surv eillance for multidrug-resistant organisms in critically ill patients, and the value of molecular typing of strains in a hospital setting to investigate spread of infection.