This work was supported by National Science Foundation grant numb

This work was supported by National Science Foundation grant number

learn more MCB-0839926 and by an endowment from the C.V. Griffin Sr. Foundation. Work in the Jez laboratory was supported by National Science Foundation grant MCB-0904215. We thank V. de Crécy-Lagard for advice. “
“From February 2010 to July 2011, 183 of 416 presumptive Klebsiella pneumoniae isolates with reduced susceptibility to third-generation cephalosporins from patients with lower respiratory tract infection were collected from seven tertiary hospitals in China. Phenotypic and genotypic methods were employed to characterize 158 extended-spectrum β-lactamase (ESBL)-producers. Among the 158 isolates analyzed, 134 (84.8%) harbored blaCTX-M, within which the most predominant ESBL gene was CTX-M-14 (49.4%), followed by CTX-M-15 (12.0%) GSK1120212 order and CTX-M-27 (10.8%). Also,

120 (75.9%) harbored blaSHV. One novel SHV variant, blaSHV-142 with T18A and L35Q substitutions, was identified. Ninety-one isolates carried blaTEM-1. An isolate containing blaTEM-135 was first identified in Klebsiella spp. blaKPC-2 was detected in 5 isolates. More than one ESBL combination was detected in 18 isolates (11.4%). Fifty-four (34.2%) isolates demonstrated the multidrug resistant (MDR) phenotype. Seventy-four sequence types (STs) were identified, which showed large genetic background diversity in ESBL-producing K. pneumoniae isolates from the six areas. This is the first report on the high prevalence of CTX-M-27 in China with the possible transmission of a single clone (ST48). The correlated surveillance of organisms with MDR phenotype should be investigated in future. Extended-spectrum Β-lactamase

(ESBL)-producing Enterobacteriaceae, especially Klebsiella pneumoniae and Escherichia coli, have been shown to have a significant impact on treatment options and clinical outcome in inpatients and outpatients (Tumbarello et al., 2007; Meier et al., 2011). Further, ESBL-producing bacteria have been shown to cause higher morbidity, Mannose-binding protein-associated serine protease mortality, and fiscal burden (Jean & Hsueh, 2011; Dhillon & Clark, 2012). The typical characteristic of ESBLs is their ability to hydrolyze oxyiminocephalosporins and aztreonam while being inhibited by β-lactamase inhibitors (Paterson & Bonomo, 2005). As the first types of ESBL derived from the non-ESBL blaSHV-1 and blaTEM-1 were reported, CTX-M-type ESBLs are now actually the most frequent types worldwide and are clustered in five subgroups (Falagas & Karageorgopoulos, 2009). Furthermore, some ESBLs exhibiting inhibitor resistance properties have also been identified in gram-negative bacteria (Nüesch-Inderbinen et al., 1997). So far, there are 124 CTX-M variants, 143 SHV variants, and 196 TEM variants, and many other types of ESBLs have been reported worldwide (http://www.lahey.org/studies). The prevalence of ESBL-producing bacteria and their antimicrobial resistance profiles vary worldwide (Dhillon & Clark, 2012).

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