RESUMO
A bla(KPC-9) carbapenemase variant was discovered in isolates of Klebsiella pneumoniae and Escherichia coli from a single patient. It differed from bla(KPC-3) by one amino acid substitution (Val239Ala). The K. pneumoniae isolate was typed as ST258, as was the epidemic Israeli KPC-3 clone. bla(KPC-9) was found on a plasmid indistinguishable from pKpQIL that carries bla(KPC-3) in the epidemic clone. Compared to KPC-3, KPC-9 conferred less resistance to carbapenems and higher resistance to ceftazidime.
Assuntos
Proteínas de Bactérias/genética , Escherichia coli/genética , Klebsiella pneumoniae/genética , Plasmídeos , Resistência beta-Lactâmica/genética , beta-Lactamases/genética , Sequência de Aminoácidos , Substituição de Aminoácidos , Antibacterianos/farmacologia , Proteínas de Bactérias/isolamento & purificação , Proteínas de Bactérias/metabolismo , Carbapenêmicos/farmacologia , Ceftazidima/farmacologia , Escherichia coli/enzimologia , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/tratamento farmacológico , Infecções por Escherichia coli/microbiologia , Humanos , Israel , Infecções por Klebsiella/tratamento farmacológico , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/enzimologia , Klebsiella pneumoniae/isolamento & purificação , Masculino , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , beta-Lactamases/isolamento & purificação , beta-Lactamases/metabolismoRESUMO
OBJECTIVES: A refractory epidemic of carbapenem-resistant Klebsiella pneumoniae (CRKP) emerged in the adult population at our hospital in 2005, as in most Israeli hospitals. Contemporaneously, a different clone of CRKP caused an easily contained outbreak in a paediatric long-term care facility (LTCF) in Jerusalem. While previously identified host-related risk factors for colonization by these organisms undoubtedly contributed to these outbreaks, it is very likely that bacterial factors might be crucial in explaining the striking differences in transmissibility between the implicated strains. We therefore sought bacterial factors associated with these different epidemiological behaviours. METHODS: Seven CRKP isolated at our hospital and the LTCF during 2008-09 were examined by antimicrobial susceptibility testing and PFGE, and further analyses of these two clones was done using multilocus sequence typing and competition experiments. Plasmids were analysed by conjugation, restriction mapping, PCR and sequencing. RESULTS: Both clones were multidrug resistant and harboured identical plasmids carrying the bla(KPC-3) gene. The hyper-transmissible epidemic clone carried additional antibiotic resistance genes and hosted an additional plasmid. The clone from the LTCF did not demonstrate hyper-transmissible properties despite its presence in an institution of a type commonly plagued by the epidemic clone. Competition assays showed the more easily contained strain to be fitter. CONCLUSIONS: These findings suggest that neither the presence of the plasmid carrying the bla(KPC-3) gene nor relative survival fitness account for the hyper-transmissibility of the epidemic strain. The role of patient age in susceptibility to colonization by the epidemic strain should be investigated.
Assuntos
Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Surtos de Doenças , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/efeitos dos fármacos , Klebsiella pneumoniae/genética , Resistência beta-Lactâmica , Adulto , Criança , Pré-Escolar , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Feminino , Genótipo , Humanos , Lactente , Israel/epidemiologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/classificação , Klebsiella pneumoniae/isolamento & purificação , Masculino , Tipagem de Sequências Multilocus , Plasmídeos/análise , Reação em Cadeia da Polimerase , Mapeamento por Restrição , Análise de Sequência de DNARESUMO
OBJECTIVES: We characterized distinctive features of a hypertransmissible carbapenem-resistant Klebsiella pneumoniae (CRKP) clone that emerged at Hadassah Hospital, Ein-Kerem, Jerusalem, Israel, in 2006. METHODS: Eleven CRKP isolated at Hadassah Hospital during 2005-09 were examined by antimicrobial susceptibility testing, PFGE and multilocus sequence typing (MLST). Plasmids were analysed by conjugation, restriction mapping, PCR and sequencing. RESULTS: Divergence from the national epidemic sequence type (ST) ST258 to ST512 was observed early on. Carbapenem resistance was conferred by bla(KPC-3) carried on a plasmid apparently closely related to pKpQIL, also from Israel. This clone also carried a 15 kb plasmid, designated pAAC154, that carries a Tn1331 derivative containing the aac(6')-Ib gene. pAAC154 does not carry a bla(KPC) gene, but is similar to pS15, a plasmid from New York that carries bla(KPC-2). CONCLUSIONS: A single CRKP clone ST512 has spread efficiently in our region. In this clone, aac(6')-Ib, common in CRKP strains, is carried on a different plasmid from bla(KPC-3).
Assuntos
Acetiltransferases/genética , Antibacterianos/farmacologia , Carbapenêmicos/farmacologia , Infecções por Klebsiella/epidemiologia , Klebsiella pneumoniae/efeitos dos fármacos , Plasmídeos , Resistência beta-Lactâmica , Análise por Conglomerados , DNA Bacteriano/química , DNA Bacteriano/genética , Eletroforese em Gel de Campo Pulsado , Genótipo , Hospitais , Humanos , Israel/epidemiologia , Infecções por Klebsiella/microbiologia , Klebsiella pneumoniae/genética , Klebsiella pneumoniae/isolamento & purificação , Testes de Sensibilidade Microbiana , Dados de Sequência Molecular , Tipagem de Sequências Multilocus , Reação em Cadeia da Polimerase , Mapeamento por Restrição , Análise de Sequência de DNARESUMO
Clinical isolates of Escherichia coli collected from 1991 through 2005 at a tertiary-care center were studied for qnr and aac(6')-Ib-cr genes. Isolates bearing aac(6')-Ib-cr emerged in 1998, coinciding with an increase in ciprofloxacin resistance. The presence of aac(6')-Ib-cr was multiclonal and was associated with the presence of extended-spectrum beta-lactamases.
Assuntos
Infecção Hospitalar/genética , Farmacorresistência Bacteriana , Escherichia coli/genética , Genes Bacterianos , Antibacterianos/farmacologia , Bacteriemia/epidemiologia , Bacteriemia/microbiologia , Escherichia coli/isolamento & purificação , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/microbiologia , Fluoroquinolonas/farmacologia , Guias como Assunto , Humanos , Testes de Sensibilidade Microbiana , Prevalência , Estudos Retrospectivos , beta-Lactamases/genéticaRESUMO
Mammalian prions refold host glycosylphosphatidylinositol-anchored PrP(C) into ß-sheet-rich PrP(Sc). PrP(Sc) is rapidly truncated into a C-terminal PrP27-30 core that is stable for days in endolysosomes. The nature of cell-associated prions, their attachment to membranes and rafts, and their subcellular locations are poorly understood; live prion visualization has not previously been achieved. A key obstacle has been the inaccessibility of PrP27-30 epitopes. We overcame this hurdle by focusing on nascent full-length PrP(Sc) rather than on its truncated PrP27-30 product. We show that N-terminal PrP(Sc) epitopes are exposed in their physiological context and visualize, for the first time, PrP(Sc) in living cells. PrP(Sc) resides for hours in unexpected cell-surface, slow moving strings and webs, sheltered from endocytosis. Prion strings observed by light and scanning electron microscopy were thin, micrometer-long structures. They were firmly cell associated, resisted phosphatidylinositol-specific phospholipase C, aligned with raft markers, fluoresced with thioflavin, and were rapidly abolished by anti-prion glycans. Prion strings and webs are the first demonstration of membrane-anchored PrP(Sc) amyloids.