ABSTRACT
Bacteria commonly associated with cases of hospital infection were isolated from samples of food, from food handless, and from objects and surfaces from different places of a hospital in Piracicaba, Säo Paulo, Brazil, and the resistance patterns of these bacteria showed a large variation, and a high frequency of resistance to ampicillin (60.9 percent), cephalothin (58.7 percent) and carbenicillin (52.2 percent) was observed. The frequency of resistance to cephalosporins of 3rd and 4th-generations was 26.1 percent and 17.4 percent of the samples, respectively. Resistance to more than two drugs was observed in 27 samples (56.5 percent), and in four strains multiple resistance to 17 or more tested drugs was recorded. Five bacteria which were multi-resistant to antibiotics (Enterobacter aerogenes, Escherichia coli, Proteus sp, Pseudomonas sp and Staphylococcus aureus) were studied to determine the chromosomal or plasmidial genetic basis of the resistance, using plasmid curing and agarose gel electrophoresis of plasmidial DNA. It was possible to verify that for the antibiobitcs chloramphenicol and kanamycin, the resistance seems to be of plasmidial origin.