cefoxitin and Acinetobacter-Infections

The mechanism of stepwise acquired multidrug resistance in Acinetobacter baumannii isolates from a hospitalized patient was investigated. Thirteen consecutive multidrug-resistant isolates were recovered from the same patient over a 2-month period. The Vitek 2 system identified the isolates as meropenem-sensitive Acinetobacter lwoffii; however, molecular identification showed that the isolates were A. baumannii. Etest revealed that the isolates were meropenem resistant. The presence of oxacillinase (OXA)-type enzymes were investigated by sequencing. The clonal relatedness of isolates was assessed by pulsed-field gel electrophoresis (PFGE). Expression of the genes encoding the efflux pumps AdeB and AdeJ was performed by semiquantitative real-time reverse transcription-PCR (qRT-PCR). The adeRS two-component system was sequenced. All isolates had identical PFGE fingerprints, suggesting clonal identity. The first six isolates were positive for the novel bla(OXA-164) gene. The following seven isolates, recovered after treatment with a combination of meropenem, amikacin, ciprofloxacin, and co-trimoxazole showed an increase of >7-fold in adeB mRNA transcripts and a missense mutation in bla(OXA-164), converting it to bla(OXA-58). Sequencing revealed a novel mutation in adeR. These data illustrate how A. baumannii can adapt during antimicrobial therapy, leading to increased antimicrobial resistance.

Topics: Acinetobacter baumannii; Acinetobacter Infections; Bacterial Proteins; Carbapenems; Drug Resistance, Bacterial; Fatal Outcome; Humans; Male; Middle Aged; Molecular Sequence Data; Mutation, Missense; Reverse Transcriptase Polymerase Chain Reaction

Based on imipenem resistance in an Acinetobacter genospecies 3 clinical isolate, we were able to identify, for the first time in this genomic species, a plasmid-encoded bla(OXA-58) gene that was 100% homologous to the same gene in Acinetobacter baumannii.

Topics: Acinetobacter; Acinetobacter Infections; Anti-Bacterial Agents; Bacterial Proteins; Base Sequence; beta-Lactamases; Carbapenems; Humans; Imipenem; Microbial Sensitivity Tests; Molecular Sequence Data; Plasmids; Sequence Analysis, DNA

By studying the beta-lactamase content of several Acinetobacter spp. isolates from Argentina, producing the expanded-spectrum beta-lactamases (ESBL) VEB-1a or PER-2, a novel Ambler class A beta-lactamase gene was identified. It encoded the narrow-spectrum beta-lactamase SCO-1, whose activity was inhibited by clavulanic acid. SCO-1 hydrolyzes penicillins at a high level and cephalosporins and carbapenems at a very low level. beta-Lactamase SCO-1 was identified from unrelated VEB-1a-positive or PER-2-positive Acinetobacter spp. isolates recovered from three hospitals. The bla(SCO-1) gene was apparently located on a plasmid of ca. 150 kb from all cases but was not associated with any ESBL-encoding gene. The G+C content of the bla(SCO) gene was 52%, a value that does not correspond to that of the A. baumannii genome (39%). beta-Lactamase SCO-1 shares 47% amino acid identity with CARB-5 and ca. 40% with the enzymes TEM, SHV, and CTX-M. A gene encoding a putative resolvase was identified downstream of the bla(SCO-1) gene, but its precise way of acquisition remains to be determined.

Topics: Acinetobacter; Acinetobacter Infections; Amino Acid Sequence; Anti-Bacterial Agents; Argentina; beta-Lactam Resistance; beta-Lactamases; beta-Lactams; Clavulanic Acid; Cloning, Molecular; Humans; Microbial Sensitivity Tests; Molecular Sequence Data; Sequence Analysis, DNA

Topics: Acinetobacter; Acinetobacter baumannii; Acinetobacter Infections; Bacterial Proteins; beta-Lactamases; Cross Infection; Humans; Plasmids; Portugal