Sixteen different sequence types (STs) of Escherichia coli isolates from a commercial swine farm in China were confirmed to coharbor the carbapenem resistance gene bla and the colistin resistance gene mcr-1. Whole-genome sequencing revealed that bla NDM-5 and mcr-1 were located on a 46-kb IncX3 plasmid and a 32-kb IncX4 plasmid, respectively. The two plasmids can transfer together with a low fitness cost, which might explain the presence of various STs of E. coli coharboring bla NDM-5 and mcr-1.KEYWORDS Escherichia coli, carbapenems, bla NDM-5 , colistin, mcr-1, fitness cost C arbapenemase-producing Enterobacteriaceae has become a major public health threat around the world (1). The recently identified carbapenemase New Delhi metallo-␤-lactamase confers resistance to all ␤-lactam antimicrobials except monobactam (2). The NDM-5-encoding gene bla NDM-5 was first identified in an Escherichia coli strain recovered from a patient in the United Kingdom in 2011 (3). Since then, bla was identified in many countries, such as Algeria (4-6), the United States (7), Australia (8), China (9-12), Denmark (13), Japan (14), India (15), and the United Kingdom (3). The widespread occurrence of NDM-5 in recent years should arouse our attention. Colistin is a critically important medication for humans in the treatment of carbapenemaseproducing Enterobacteriaceae, and it has been widely used in veterinary medicine in China (16,17). The first plasmid-mediated colistin resistance gene, mcr-1, was reported in E. coli in 2015 (18). In a short period, colistin-resistant E. coli carrying the mcr-1 gene were reported worldwide (19,20). Recently, mcr-1 was reported to coexist with bla NDM (21-23) and bla CTX-M (24), which brought great challenges for the treatment of bacterial infection. In the present study, we are the first to report the presence of isolates of various sequence types of E. coli coharboring bla NDM-5 and mcr-1 genes from a commercial pig farm in China.A total of 105 anal swabs samples from swine were collected from a commercial pig farm on 1 October 2015 in Sichuan province. E. coli strains were selected by eosinmethylene blue agar, and only 1 isolate was picked up from each sample. All 105 isolates were identified by BD Phoenix 100 diagnostic systems (Sparks, MD). Sixty-four strains were nonsusceptible to imipenem and polymyxin B, identified by the agar dilution method according to Clinical and Laboratory Standards Institute guidelines (25). Isolates were divided into 16 different clones by pulsed-field gel electrophoresis after XbaI digestion according to the standard PulseNet conditions (26) (Fig. 1). Phy-

This study aims at investigating the distribution, antimicrobial resistance, and genetic relationship of Salmonella isolated from 18 farms, their downstream abattoirs, and markets of chickens and pigs in Sichuan province, China. A total of 193 Salmonella isolates were identified from 693 samples with an isolation rate of 26.27% (88/335) in chickens and 29.33% (105/358) in pigs. Salmonella was isolated more frequently in abattoirs and markets than from farms. Serotypes were determined according to the White-Kauffmann-Le Minor scheme and 16 different serotypes were identified, with Derby being the most common, followed by Typhimurium and Meleagridis. Antimicrobial resistance phenotypes and genotypes were studied by using the disk diffusion method and polymerase chain reaction (PCR) amplification, respectively. Overall, 44.04% (n = 85) of all isolates were multidrug resistant (MDR) and resistance to nalidixic acid (51.30%) was the most frequently observed. bla was the most prevalent extended-spectrum β-lactamases gene, and polymyxin resistance gene mcr-1 was present in strains with various serotypes. Multilocus sequence typing indicated that sequence type (ST) had a close relationship with serotype, and 34.20% of all strains were ST40, which was the most prevalent. The unweighted pair group method with arithmetic means (UPGMA) dendrogram of pulsed-field gel electrophoresis showed that Salmonella isolates belonging to the same serovar from different parts of the production chain were highly genetic related, indicating that Salmonella as well as resistance genes could potentially be transmitted from farms to markets. Our study highlights the fact that Salmonella isolates from chicken and pig production chain were frequently exhibiting MDR profiles, and the dissemination of MDR Salmonella from farm to market could pose significant threats to food safety and public health.

While the health effects of the colonization of the reproductive tracts of mammals by bacterial communities are widely known, there is a dearth of knowledge specifically in relation to giant panda microbiomes. In order to investigate the vaginal and uterine bacterial diversity of healthy giant pandas, we used high-throughput sequence analysis of portions of the 16S rRNA gene, based on samples taken from the vaginas (GPV group) and uteri (GPU group) of these animals. Results showed that the four most abundant phyla, which contained in excess of 98% of the total sequences, were Proteobacteria (59.2% for GPV and 51.4% for GPU), Firmicutes (34.4% for GPV and 23.3% for GPU), Actinobacteria (5.2% for GPV and 14.0% for GPU) and Bacteroidetes (0.3% for GPV and 10.3% for GPU). At the genus level, Escherichia was most abundant (11.0%) in the GPV, followed by Leuconostoc (8.7%), Pseudomonas (8.0%), Acinetobacter (7.3%), Streptococcus (6.3%) and Lactococcus (6.0%). In relation to the uterine samples, Janthinobacterium had the highest prevalence rate (20.2%), followed by Corynebacterium (13.2%), Streptococcus (19.6%), Psychrobacter (9.3%), Escherichia (7.5%) and Bacteroides (6.2%). Moreover, both Chao1 and abundance-based coverage estimator (ACE) species richness indices, which were operating at the same sequencing depth for each sample, demonstrated that GPV had more species richness than GPU, while Simpson and Shannon indices of diversity indicated that GPV had the higher bacterial diversity. These findings contribute to our understanding of the potential influence abnormal reproductive tract microbial communities have on negative pregnancy outcomes in giant pandas.