Antibiotic resistance in salmonellae isolated from humans and animals in France: comparative data from 1994 and 1997

Among 25 526 recorded isolates of salmonellae, 5086 isolated from humans an d 20440 from animals in 1994 and 1997 in France, the antibiotic resistance phenotype was determined for all human and 5336 animal isolates. In Salmone lla enterica serovar typhimurium, one of the two most frequently isolated s erovars from humans as well as animals, resistance to ampicillin was observ ed in 61% of both human and animal isolates in 1994 and in 73% of human and 53% of animal isolates in 1997. During these periods, resistance to co-amo xiclav was between 45% and 66% for both types of isolate. Resistance to amp icillin was associated with resistance to streptomycin, spectinomycin, sulp honamide, tetracycline and chloramphenicol in over. 70% of isolates. Resist ance to ampicillin as well as co-amoxiclav never exceeded 7% in Salmonella enteritidis. While Salmonella hadar was practically absent among the human isolates in 1994, this serovar was the third most frequent in 1997, and at that time 92% were resistant to nalidixic acid. Among the animal S. hadar i solates, the prevalence of resistance to nalidixic acid increased from 3% i n 1994 to 72% in 1997. None of these isolates manifested high-level resista nce to ofloxacin. The levels of resistance to aminoglycosides (less than or equal to 3%) and trimethoprim-suphamethoxazole (less than or equal to 14%) remained practically unchanged in all three serovars. The resistance marke rs of 463 ampicillin-resistant S. typhimurium isolated in 1997 were determi ned. Among the 24 phenotypes observed, six multiresistance phenotypes, repr esenting 82% of these isolates (as compared with 80% in 1994), were associa ted with the PSE-1 gene typically found in the lysotype DT104 of this serov ar.