RESUMO
Escherichia coli (328 isolates), Klebsiella pneumoniae (296), Klebsiella oxytoca (44), and Proteus mirabilis (33) isolates collected during 2012 from the nine U.S. census regions and displaying extended-spectrum-ß-lactamase (ESBL) phenotypes were evaluated for the presence of ß-lactamase genes, and antimicrobial susceptibility profiles were analyzed. The highest ESBL rates were noted for K. pneumoniae (16.0%, versus 4.8 to 11.9% for the other species) and in the Mid-Atlantic and West South Central census regions. CTX-M group 1 (including CTX-M-15) was detected in 303 strains and was widespread throughout the United States but was more prevalent in the West South Central, Mid-Atlantic, and East North Central regions. KPC producers (118 strains [112 K. pneumoniae strains]) were detected in all regions and were most frequent in the Mid-Atlantic region (58 strains). Thirteen KPC producers also carried blaCTX-M. SHV genes encoding ESBL activity were detected among 176 isolates. Other ß-lactamase genes observed were CTX-M group 9 (72 isolates), FOX (10), TEM ESBL (9), DHA (7), CTX-M group 2 (3), NDM-1 (2 [Colorado]), and CTX-M groups 8 and 25 (1). Additionally, 62.9% of isolates carried ≥2 ß-lactamase genes. KPC producers were highly resistant to multiple agents, but ceftazidime-avibactam (MIC50/90, 0.5/2 µg/ml) and tigecycline (MIC50/90, 0.5/1 µg/ml) were the most active agents tested. Overall, meropenem (MIC50, ≤0.06 µg/ml), ceftazidime-avibactam (MIC50, 0.12 to 0.5 µg/ml), and tigecycline (MIC50, 0.12 to 2 µg/ml) were the most active antimicrobials when tested against this collection. NDM-1 producers were resistant to all ß-lactams tested. The diversity and increasing prevalence of ß-lactamase-producing Enterobacteriaceae have been documented, and ceftazidime-avibactam was very active against the vast majority of ß-lactamase-producing strains isolated from U.S. hospitals.
Assuntos
Antibacterianos/uso terapêutico , Ceftazidima/análogos & derivados , Variação Genética , Minociclina/análogos & derivados , Monobactamas/uso terapêutico , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Ceftazidima/uso terapêutico , Infecções por Enterobacteriaceae/tratamento farmacológico , Infecções por Enterobacteriaceae/epidemiologia , Infecções por Enterobacteriaceae/microbiologia , Escherichia coli/efeitos dos fármacos , Escherichia coli/enzimologia , Escherichia coli/genética , Expressão Gênica , Humanos , Klebsiella oxytoca/efeitos dos fármacos , Klebsiella oxytoca/enzimologia , Klebsiella oxytoca/genética , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/genética , Testes de Sensibilidade Microbiana , Minociclina/uso terapêutico , Plasmídeos , Proteus mirabilis/efeitos dos fármacos , Proteus mirabilis/enzimologia , Proteus mirabilis/genética , Tigeciclina , Estados Unidos/epidemiologia , Resistência beta-Lactâmica/efeitos dos fármacos , beta-Lactamases/metabolismoRESUMO
Enterobacteriaceae bacteremia isolates (n = 195; 6.4% overall) collected from 26 U.S. hospitals located in 20 states were screened for various ß-lactamase classes. A total of 175 isolates carried one to eight acquired ß-lactamase genes of 44 types that were detected in 55 combinations. Eighty-five (43.6%) strains carried blaCTX-M, and blaCTX-M-15 was the most prevalent (33.8%). Genes encoding OXA-1/30 (often associated with blaCTX-M-15), CMY-2, SHV extended-spectrum ß-lactamase (ESBLs), and TEM-1 were also prevalent. Among 33 carbapenem-resistant strains, 28 carried blaKPC-2 or blaKPC-3 (17 and 11 strains, respectively), and those were recovered mostly in the New York City area (16 strains) and Houston, TX (9 strains). Fourteen new SHV variants were identified among Klebsiella pneumoniae isolates carrying one or multiple SHV alleles, three carrying G238S and/or E240K amino acid alterations that confer ESBL activity. Only two of eight K. oxytoca isolates carried acquired ß-lactamases, but most had mutations on the blaOXY promoter region, and three new OXY-encoding genes were characterized. Concordance between a commercial nucleic acid-based microarray (Check-MDR CT101) and reference methods was noted for 105/109 (97.2%) strains. Thirty-two strains having genes that are not targeted by the commercial system were detected (OXA ESBLs, PER, PSE, or intrinsic genes). Overall, a great variety of enzymes were observed, with numerous strains carrying multiple genes. Rates of CTX-M-producing strains appear to be increasing in U.S. hospitals (26.6% in 2007 to 43.8% for 2010) participating in the SENTRY Program. Furthermore, the Check-Points system seems to be a reliable, robust, and user-friendly assay for detection of enzyme-mediated resistance.
Assuntos
Bacteriemia/microbiologia , Infecções por Enterobacteriaceae/microbiologia , Enterobacteriaceae/efeitos dos fármacos , Enterobacteriaceae/genética , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Bacteriemia/tratamento farmacológico , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Sequência de Bases , Carbapenêmicos/farmacologia , DNA Bacteriano/genética , Enterobacteriaceae/enzimologia , Enterobacteriaceae/isolamento & purificação , Infecções por Enterobacteriaceae/tratamento farmacológico , Genótipo , Hospitais , Humanos , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Mutação , Regiões Promotoras Genéticas , Análise de Sequência de DNA , Estados Unidos , beta-Lactamas/farmacologiaRESUMO
During 2007 to 2010, 23 carbapenem-resistant Enterobacteriaceae strains were recovered in two hospitals in Texas among three institutions surveyed. Eighteen (2.0% overall) strains carried bla(KPC-2) and were collected in 2008 (3/150; 2.0%) and 2010 (15/289; 5.1%). Clonality was noted within hospitals and ten isolates belonged to ST258. All strains carried bla(KPC-2) on plasmids and 14 had this gene embedded in Tn4401a. Tn3 transposase was detected upstream of bla(KPC-2) in two isolates and another strain had two adjacent copies of bla(KPC). Surveillance in prior years shows sporadic detection of KPC-producers in Texas, however, a recent increase in carbapenem-resistant Enterobacteriaceae in this state was due to the spread of KPC-producing Klebsiella pneumoniae, including isolates from ST258.
Assuntos
Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/genética , Plasmídeos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Eletroforese em Gel de Campo Pulsado , Humanos , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/isolamento & purificação , Testes de Sensibilidade Microbiana , Análise de Sequência de DNA , Texas/epidemiologia , Resistência beta-Lactâmica/efeitos dos fármacos , beta-Lactamases/metabolismoRESUMO
Thirteen NDM-1-producing Enterobacteriaceae, representing all carbapenem-resistant strains (5.2% overall) collected in 3 Indian hospitals during 2010, were analyzed. Eleven genetically distinct strains of 4 bacterial species were observed. All 3 E. coli strains belonged to ST101. Strains harbored bla(CTX-M-15) and at least 1 other ß-lactamase. Fluoroquinolone and aminoglycoside resistance genes were detected in 11 and 6 strains, respectively. bla(NDM-1) was carried in plasmids of various sizes and incompatibility types, and 3 were transferred by conjugation. This study confirms the ability of bla(NDM-1) to disseminate among different bacterial species and the genetic variability of the structures carrying this metallo-ß-lactamase gene in India.