Antimicrobial Resistance and R-Factor Transfer among Isolates of Salmonella in the Northeastern United States: A Comparison of Human and Animal Isolates

Abstract

The antimicrobial susceptibility of 718 isolates of Salmonella from humans and of 688 isolates from animals was examined. Of the 46 different serotypes among the isolates from humans, Salmonella typhimurium accounted for 34%. Thirty percent of isolates were resistant to one or more antibiotic(s). Resistance to streptomycin was most common; resistance to tetracycline was next most common. Over 50% of isolates of S. typhimurium and Salmonella newport were resistant to four antibiotics. Resistance to tetracycline, kanamycin, and ampicillin has increased steadily during the past decade. Most strains possessed R-factors, and resistance to ampicillin, streptomycin, sulfisoxazole, tetracycline, chloramphenicol, and kanamycin (but not that to cephalothin) was transferable. Among the salmonellae commonly isolated from humans, only Salmonella enteritidis showed limited resistance to antibiotics (5.8%). Antibiotic resistance of isolates of S. typhimurium, Salmonella saint-paul, and Salmonella heidelberg from animals was similar to the resistance of isolates from humans. Resistance to kanamycin increased markedly over the level noted in previous studies. R-factor prevalence was high. Antibiograms of the isolates from animals and humans were similar, although some patterns were seen only in isolates from one source. Ampicillin resistance was more common in human isolates, and resistance to tetracycline, sulfonamide, and streptomycin was more common in animal isolates. Salmonellae of serotypes other than S. typhimurium that came from humans were less resistant to all antibiotics than were isolates from animals.

Antibiotic resistance among salmonella from human and other sources in New Zealand

“…The comparable rate for New Zealand in 1987 was 10%. An earlier study in 1973 in the United States reported resistance among 30 % of salmonella from humans and 70 % among isolates from animals [9]. In England and Wales in 1987, 23% of salmonella from human sources were antibiotic resistant.…”

Antimicrobial resistance and incompatibility groups of R plasmids in Salmonella typhimurium isolated from human sources in Bombay from 1978 to 1980

“…Since 1962, R plasmids have been noticed in Salmonella typhimurium isolated in various regions of the world (2,11,13,17,19,20), and a geographical predominance of resistance transfer systems characterized mainly by their incompatibility groups has been identified (2). In India, sporadic cases of salmonellosis due to drugresistant S. typhimurium have been recorded in Vellore (16) since 1968, but in the last few years plasmid-bearing, multidrug-resistant strains have emerged in various parts of the country (21).…”

Salmonella serotypes, Salmonella typhi phage types, and anti-microbial resistance at the University Hospital of the West Indies, Jamaica

“…Number of grams of ampictllin and chloramphenicol dispensed by the hospital pharmacy, University Hospital of the West Indies, 1969-1975 1969 1970 1971 1972 1973 1974 1975 Ampicillin 11863 17213 13064 22194 33833 34735 32578 Chloramphenicol NA NA 11529 10248 16059 11534 14308 NA; figures not available. is transmissible. James, Wells & Grant, (1973) have shown that transmissible resistance does occur in other gram-negative organisms isolated at this hospital, and transmissible resistance in salmonellas is common elsewhere (Neu et al 1975;Anderson, 1974).…”