The aim of the present study was to investigate the antibiotic resistance profiles and the molecular epidemiology of extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates from two production swine operations in Sichuan Province, China, between August 2002 and February 2007. The prevalence of ESBL-producing E. coli increased dramatically from 2.2% to 10.7% during this period. This increase appeared mostly related to dissemination of CTX-M-type ESBLs among E. coli isolates. Of 212 E. coli isolates studied, 14 harbored ESBL genes. Among them, 13 harbored bla(CTX-M-15/22) and one harbored bla(SHV-2). To our knowledge, this is the first study to identify bla(CTX-M-22) from production animals. One isolate in 2002 harbored bla(SHV-2), indicating that ESBL genes have been present in farm animals in China since at least 2002. Molecular characterization and pulsed-field gel electrophoresis of the ESBL-producing isolates suggested that different mechanisms may be involved in the dissemination of the CTX-M genes and revealed that additional resistance determinants for non-beta-lactam antibiotics were carried by plasmids encoding certain ESBL genes. Results of this study provide an example of how ESBL genes, particularly those of CTX-M lineages, are rapidly spreading among E. coli isolates from commercial pig farms in Sichuan province of China.

Tibetan Chickens should have unique gastrointestinal microbiota because of their particular habitats. Thus, the aim of this study was to investigate the cecal microbiota of Tibetan Chickens from five typical high‐altitude regions of China. Lohmann egg‐laying hens (LMs) and Daheng broiler chickens (DHs) were chosen as controls. The cecal bacterial populations of Tibetan Chickens were surveyed by high‐throughput sequencing (HTS) of the bacterial 16S rRNA hypervariable region V3‐V4 (16S rRNAV3‐V4) combined with community‐fingerprinting analysis of the 16S rRNA gene based on polymerase chain reaction‐denaturing gradient gel electrophoresis (PCR‐DGGE). The results revealed that the majority of cecal microbiota differed between the Tibetan Chicken and LM/DH. The microbial communities in the cecum were composed of 16 phyla, 28 classes, 36 orders, 57 families, 101 genera, and 189 species. Represented phyla were Bacteroidetes (>47%), Firmicutes (>18.8%), Spirochaetae (>0.3%), and Proteobacteria (>0.4%). Bacteroides and the RC9 gut group were the two most abundant genera. There were relatively more Christensenellaceae, Subdoligranulum, Spirochaeta, and Treponema in Tibetan Chickens, whereas there were more Phascolarctobacterium, Faecalibacterium, Megamonas, and Desulfovibrio in LMs and DHs. The cecal microbiota of Tibetan Chicken have slightly diverged due to exposure to different geographic environments. Differences in the intestinal bacterial communities of Tibetan Chicken and LM/DH were noted.

No abstract

No abstract