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This study aimed to determine the prevalence of extended-spectrum beta-lactamases (ESBLs) in Enterobacteriaceae and to characterize the genetic composition of ESBL determinants among Enterobacteriaceae isolates from healthy people in Guangzhou, China. A total of 200 rectal swab samples were collected from healthy asymptomatic individuals and tested for ESBL production using ChromID ESBL agar. Phenotypic ESBL producers were screened for blaCTX-M, blaTEM, and blaSHV genes using PCR and DNA sequencing. The prevalence of ESBL-producing Enterobacteriaceae among rectal swab samples was 69.5%. All ESBL-producing isolates harbored blaCTX-M genes ( n=138) except for one isolate that harbored blaSHV-2a. Eleven CTX-M ESBL genes were detected. The most predominant CTX-M-type genes were blaCTX-M-14 ( n=82), followed by blaCTX-M-55 ( n=19), blaCTX-M-65 ( n=10), and blaCTX-M-27 ( n=9). Isolates carrying blaCTX-M-38,-3,-15,-14b,-98,-121 and -123 were also identified. Molecular homology analysis of the selected isolates was performed by phylogenetic grouping and multilocus sequence typing and indicated that the predominant clone belonged to A-CC10. This study showed a high rate of CTX-M-type ESBL genes among Enterobacteriaceae isolates from healthy individuals in China. [ABSTRACT FROM AUTHOR]

We investigated the distribution of resistance genes and the clonal relationships among carbapenem-resistant Acinetobacter baumannii isolates from the intensive care unit wards of two hospitals in Guangzhou, China. From 2012 to 2013, 57 A. baumannii isolates were obtained from blood cultures from two hospitals in Guangzhou. The antibiotic resistance profiles were determined by using the Vitek2 system and Etest strips. PCR was used to detect the genes encoding OXA-type carbapenemases and metallo-β-lactamases and the presence of IS Aba1 upstream of the blaOXA-51-like gene and the blaOXA-23-like gene. Multilocus sequence typing (MLST) and sequence-based typing of blaOXA-51-like genes (SBT- blaOXA-51-like genes) were performed to analyze the genetic relationship of the isolates. Among the 57 isolates, 46 were carbapenem-resistant A. baumannii (CRAB) isolates. The blaOXA-51-like gene was identified in all 57 isolates, while the blaOXA-23-like gene was present in all 46 CRAB isolates. The MLST analysis grouped the A. baumannii isolates into five existing sequence types (STs) and five new STs. Fifty-two isolates belonged to the worldwide spread of clonal complex 92 (CC92), among which ST195 and ST365 were the most common STs. The MLST data and SBT- blaOXA-51-like genes showed that all isolates harboring the major blaOXA-51-like alleles, such as blaOXA-66, belonged to CC92. [ABSTRACT FROM AUTHOR]