RESUMO
The gene bla(CARB-9) was located in the Vibrio cholerae super-integron, but in a different location relative to bla(CARB-7). CARB-9 (pI 5.2) conferred beta-lactam MICs four to eight times lower than those conferred by CARB-7, differing at Ambler's positions V97I, L124F, and T228K. Comparison of the genetic environments of all reported bla(CARB) genes indicated that the CARB enzymes constitute a family of cassette-encoded beta-lactamases.
Assuntos
Penicilinase/genética , Vibrio cholerae/enzimologia , Vibrio cholerae/genética , beta-Lactamases/genética , Sequência de Aminoácidos , Argentina , Dados de Sequência Molecular , Penicilinase/classificação , Sequências Repetitivas de Aminoácidos , beta-Lactamases/classificação , beta-Lactamases/metabolismoRESUMO
Carbapenemases may be defined as beta-lactamases that significantly hydrolyze at least imipenem or/and meropenem. Carbapenemases involved in acquired resistance are of Ambler molecular classes A, B, and D. Class A, clavulanic acid-inhibited carbapenemases are rare. They are either chromosomally encoded (NMC-A, Sme-1 to Sme-3, IMI-1) in Enterobacter cloacae and Serratia marcescens, or plasmid encoded, such as KPC-1 in Klebsiella pneumoniae and GES-2 in Pseudomonas aeruginosa, the latter being a point-mutant of the clavulanic acid-inhibited extended-spectrum beta-lactamase GES-1. The class B enzymes are the most clinically significant carbapenemases. They are metalloenzymes of the IMP or VIM series. They have been reported worldwide but mostly from South East Asia and Europe. Metalloenzymes, whose genes are plasmid and integron located, hydrolyze virtually all beta-lactams except aztreonam. Finally, the class D carbapenemases are increasingly reported in Acinetobacter baumannii but compromise imipenem and meropenem susceptibility only marginally. The sources of the acquired carbapenemase genes remain unknown, as does the relative importance of the spread of epidemic strains as opposed to the spread of plasmid- or integron-borne genes. Because most of these carbapenemases confer only reduced susceptibility to carbapenems in Enterobacteriaceae, they may remain underestimated as a consequence of the lack of their detection.
Assuntos
Proteínas de Bactérias , Proteínas de Ciclo Celular , Bactérias Aeróbias Gram-Negativas/enzimologia , Proteínas de Saccharomyces cerevisiae , beta-Lactamases/biossíntese , Sequência de Aminoácidos , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Ácido Clavulânico/metabolismo , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular , Dados de Sequência Molecular , Penicilinase/classificação , Proteínas Quinases/genética , Proteínas Quinases/metabolismo , Proteínas Serina-Treonina Quinases , Alinhamento de Sequência , beta-Lactamases/classificação , beta-Lactamases/genética , beta-Lactamases/metabolismoRESUMO
The sequences of the promoter regions and of the structural genes for 13 penicillinase, extended-spectrum, and inhibitor-resistant TEM-type beta-lactamases have been determined, and an updated blaTEM gene nomenclature is proposed.
Assuntos
Enterobacteriaceae/genética , Penicilinase/genética , Regiões Promotoras Genéticas , beta-Lactamases/genética , DNA Bacteriano/análise , Dados de Sequência Molecular , Penicilinase/classificação , Terminologia como Assunto , Inibidores de beta-Lactamases , beta-Lactamases/classificaçãoAssuntos
beta-Lactamases/classificação , Cefuroxima/metabolismo , Cefalosporinase/classificação , Cromossomos Bacterianos , Bactérias Gram-Negativas/enzimologia , Bactérias Gram-Positivas/enzimologia , Métodos , Penicilinase/classificação , Plasmídeos , Especificidade por Substrato , beta-Lactamases/análise , beta-Lactamases/genéticaRESUMO
R factor-determined beta-lactamases have been investigated by analytical isoelectric focusing. The enzymes such as those specified by the R6K and RP4 plasmids (TEM-type enzymes) are notably homogenous in biochemical tests (Hedges et al., 1974), but two subclasses can be distinguished by isoelectric focusing. Three subclasses can be distinguished among the oxacillin-hydrolyzing enzymes, in good agreement with the classification based upon biochemical characteristics (Dale and Smith, 1974). The TEM-type beta-lactamases are promiscuously distributed among plasmids of a wide variety of compatibility groups, whereas the various oxacillin-hydrolyzing enzymes show some degree of correlation with compatibility.
