Propagation of TEM- and PSE-type beta-lactamases among amoxicillin-resistant Salmonella spp. isolated in France.
A survey conducted between 1987 and 1994 at the University Hospital of Besançon, France, demonstrated a dramatic increase (from 0 to 42. 5%) in the prevalence of amoxicillin resistance among Salmonella spp. Of the 96 resistant isolates collected during this period (including 77 Typhimurium), 54 were found to produce TEM-1 beta-lactamase, 40 produced PSE-1 (equivalent to CARB-2), one produced PSE-1 plus TEM-2, and one produced OXA-1 in isoelectric focusing and DNA hybridization experiments. Plasmids coding for these beta-lactamases were further characterized by (i) profile analysis, (ii) restriction fragmentation pattern analysis, (iii) hybridization with an spvCD-orfE virulence probe, and (iv) replicon typing. In addition, isolates of S. typhimurium were genotypically compared by pulsed-field gel electrophoresis of XbaI-macrorestricted chromosomal DNA. Altogether, these methods showed that 40 of the 41 PSE-1 producers were actually the progeny of a single epidemic S. typhimurium strain lysotype DT104. Isolates of that strain were found to harbor RepFIC virulence plasmids with somewhat different restriction profiles, but which all carried the bla(PSE-1) gene. Of these virulence/resistance plasmids, 15 were transmissible to Escherichia coli. TEM-1-producing S. typhimurium displayed much greater genotypic and plasmidic diversities, suggesting the acquisition of the bla(TEM-1) gene from multiple bacterial sources by individual strains. In agreement with this, 32 of the 35 S. typhimurium plasmids encoding TEM-1 were found to be conjugative. These data show that development of amoxicillin resistance among Salmonella, especially in serovar Typhimurium, results from both gene transfers and strain dissemination.
Llanes
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Laboratoire de Bactériologie, Faculté de Médecine, Université de Franche-Comté, 25030 Besançon, France.
Kirchgesner
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Plesiat
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P
D000658:Amoxicillin / Q000494:pharmacology; D005602:France; D018014:Gene Transfer Techniques; D006801:Humans; D010403:Penicillin Resistance; D010406:Penicillins / Q000494:pharmacology; D011815:R Factors / Q000235:genetics; D012093:Replicon / Q000235:genetics; D015183:Restriction Mapping; D012475:Salmonella / Q000187:drug effects / Q000201:enzymology / Q000235:genetics*; D014169:Transformation, Bacterial; D001618:beta-Lactamases / Q000235:genetics* / Q000378:metabolism
D010406:Penicillins; D000658:Amoxicillin; C064821:beta-lactamase PSE-1; D001618:beta-Lactamases; C034413:beta-lactamase TEM-1