CHANGES IN SUSCEPTIBILITY OF SALMONELLA-ENTERITIDIS, SALMONELLA-TYPHIMURIUM, AND SALMONELLA-VIRCHOW TO 6 ANTIMICROBIAL AGENTS IN A SPANISH HOSPITAL, 1980-1994

To determine changes in the susceptibility patterns of Salmonella ente ritidis, Salmonella typhimurium, and Salmonella virchow over time, res istance to ampicillin, chloramphenicol, tetracycline, gentamicin, trim ethoprim/sulfamethoxazole, and nalidixic acid was studied by the disk diffusion method in 1,024, 191, and 61 clinical isolates of these orga nisms, respectively. All isolates were recovered from 1980 to 1994 at a hospital in Madrid, Spain, Salmonella enteritidis isolates were less resistant (10.9%) than Salmonella typhimurium (43.5%) and Salmonella virchow (36.1%; p < 0.001). The incidence of resistance of Salmonella enteritidis to ampicillin increased from 2.7% during the period 1980-1 982 to 15.6% during 1992-1994 (p < 0.001). The resistance of Salmonell a typhimurium to ampicillin, chloramphenicol, and tetracycline increas ed from 15.2%, 7.6%, and 21.2% respectively in 1980-1982 to 73.3%, 46. 7%, and 73.3% in 1992-1994 (p < 0.001). These marked increases in anti microbial resistance suggest the need for public health interventions, several of which are discussed.