[Phenotypes of beta-lactam resistance in the genus Aeromonas].
This work aimed to investigate resistance profiles towards beta-lactam antibiotics in correlation with beta-lactamases production in the genus Aeromonas. In a series of 417 wild-type strains, biochemical identification and testing with 11 beta-lactams by the disk-diffusion method revealed 5 predominant phenotypes: A. hydrophila complex/class B, C and D beta-lactamases; A. caviae complex/class C and D beta-lactamases; A. veronii complex/class B and D beta-lactamases; A. schubertii spp./class D beta-lactamase; A. trota spp./class C beta-lactamase. A subgroup of 64 representative strains was submitted to MIC determination with 8 beta-lactam compounds alone and in combination with 3 beta-lactamase inhibitors (clavulanic acid, tazobactam and BRL 42715). Visualisation of beta-lactamases and pI determination were performed in all these 64 isolates by isoelectric focusing from crude extracts. The different Aeromonas species produced 1 to 3 of the following inducible enzymes: an imipenemase with low expression, which is difficult to detect with routine phenotype studies (class B, pI 8, imipenem MIC > 2 micrograms/ml), a cephalosporinase (class C, pI > 7 +/- 0.5, cephalothin MIC > 256 micrograms/ml), and an oxacillinase widely produced in the genus Aeromonas (class D, pI > 8.5, ticarcillin MIC > 256 micrograms/ml). In Aeromonas spp. resistance profile to beta-lactam antibiotics is correlated with naturally occurring phenotypes of beta-lactamases production. As a conclusion, the characterisation of these different enzymes is of therapeutic and taxonomic interest, in species notoriously difficult to identify.
Fosse
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T
Laboratoire de bactériologie, hôpital l'Archet 2, Centre Hospitalier Universitaire, BP 3079, 06202 Nice, France. fosse.t@chu-nice.fr
Giraud-Morin
C
C
Madinier
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I
D000333:Aeromonas / Q000145:classification / Q000187:drug effects / Q000201:enzymology; D019818:Clavulanic Acid / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007525:Isoelectric Focusing; D007526:Isoelectric Point; D007769:Lactams; D008826:Microbial Sensitivity Tests; D010397:Penicillanic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D010641:Phenotype; D000078142:Tazobactam; D018440:beta-Lactam Resistance; D065093:beta-Lactamase Inhibitors; D001618:beta-Lactamases / Q000032:analysis / Q000096:biosynthesis; D047090:beta-Lactams
D004791:Enzyme Inhibitors; D007769:Lactams; D065093:beta-Lactamase Inhibitors; D047090:beta-Lactams; C061593:C6-(N1-methyl-1,2,3-trazolylmethylene)penem; D019818:Clavulanic Acid; D010397:Penicillanic Acid; D001618:beta-Lactamases; D000078142:Tazobactam