Poultry and livestock are the most important reservoirs for pathogenic Escherichia coli and use of antimicrobials in animal farming is considered the most important factor promoting the emergence, selection and dissemination of antimicrobial-resistant microorganisms. The aim of our study was to investigate antimicrobial resistance in E. coli isolated from food animals in Jiangsu, China. The disc diffusion method was used to determine susceptibility to 18 antimicrobial agents in 862 clinical isolates collected from chickens, ducks, pigs, and cows between 2004 and 2012. Overall, 94% of the isolates showed resistance to at least one drug with 83% being resistance to at least three different classes of antimicrobials. The isolates from the different species were most commonly resistant to tetracycline, nalidixic acid, sulfamethoxazole, trimethoprim/sulfamethoxazole and ampicillin, and showed increasing resistance to amikacin, aztreonam, ceftazidime, cefotaxime, chloramphenicol, ciprofloxacin. They were least resistant to amoxicillin/clavulanic acid (3.4%) and ertapenem (0.2%). MDR was most common in isolates from ducks (44/44, 100%), followed by chickens (568/644, 88.2%), pigs (93/113, 82.3%) and cows (13/61, 21.3%). Our finding that clinical E. coli isolates from poultry and livestock are commonly resistant to multiple antibiotics should alert public health and veterinary authorities to limit and rationalize antimicrobial use in China.

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To add to the limited information on Rickettsia in mosquitoes in China, we carried out a PCR survey on convenience samples of 3051 mosquitoes collected with hand nets in and around domestic dwellings in 25 provinces. Five species of mosquitoes were identified: Culex pipiens pallens (n = 1620), Aedes albopictus (806), Armigeres subalbatus (377), Anopheles sinensis (168), and Culex tritaeniorhynchus (80). A Rickettsia nested-PCR targeting the variable domain of gltA showed Rickettsia felis in four mosquito species of 16 provinces Cx. pipiens pallens (1.8%, 29/1620); Ae. albopictus (1.2%, 10/806); An. sinensis (1.2%, 2/168); and Ar. subalbatus (2.1%, 8/377). Rickettsia bellii was also widespread, occurring in 12 provinces and 2 species: Cx. pipiens pallens (4.3%, 69/1620) and An. sinensis (0.6%, 1/168). R. felis and R. bellii were found in almost similar numbers in female [1.5% (27/1809) and 1.2% (21/1809), respectively] as in male mosquitoes [1.8% (22/1242) and 4.0% (49/1242), respectively]. Our results indicated that mosquitoes in China are widely infected with R. felis, the agent of human flea-borne spotted fever, and that R. bellii can also occur outside of the Americas and its usual tick hosts.

ObjectiveColistin resistance has emerged worldwide and has been threatening the efficacy of one of the last-resort antimicrobials used for treatment of multidrug resistant Gram-negative bacteria. While five colistin resistance genes (mcr-1, mcr-2, mcr-3, mcr-4 and mcr-5) have been described, few data are available on the prevalence of mcr-genes other than mcr-1 in human samples.ResultsIn this study, the presence of five currently described colistin resistance genes (mcr 1–5) in vaginal swabs of women undergoing infertility evaluation was reported. Most samples were found to be positive for the mcr-4 (12.7%), followed by two for the mcr-2 (1.5%), two for the mcr-3 (1.5%), one for the mcr-1 (0.7%), and one for the mcr-5 (0.7%). Phylogenetic comparison demonstrated identical (mcr-1, mcr-2, mcr-3, mcr-5) or similar (mcr-4) nucleotide sequences of human samples and those of animal origins from the same city, suggesting the potential transmission of mcr genes from animals to humans. This is the first detection of mcr-2, mcr-4 and mcr-5 genes in human samples, and warrants further research to determine the spread of the mcr genes and elucidate the full epidemiology of colistin resistance genes in humans.

Anaplasma spp. and Ehrlichia spp. are tick-transmitted bacteria that are of significant economic importance as they can infect large and small ruminants and also people. There is little information on anaplasmosis and ehrlichiosis in ruminants in China. 16S rRNA FRET-qPCRs were used to screen convenience whole blood samples from 2,240 domestic ruminants in 12 provinces of China for Anaplasma spp. and Ehrlichia spp. Positive samples were further analyzed with a standard PCR for the gltA. Anaplasma spp. DNA was detected in the sheep (11.7%; 13/111), goats (81.8%; 219/270), cattle (13.2%; 241/1,830), and water buffaloes (6.9%; 2/29). Ehrlichia spp. DNA was detected in sheep (1.8%; 2/111), goats (1.1%; 3/270), and cattle (3.6%; 65/1830) but not in water buffaloes (0/29). Sequencing of gltA PCR products showed that A. marginale, A. ovis, Ehrlichia canis, and Ehrlichia sp. (JX629807) were present in ruminants from China, while the 16S rRNA FRET-qPCR sequence data indicated that there might also be A. platys, A. phagocytophilum, Anaplasma sp. BL126-13 (KJ410243), and Anaplasma sp. JC3-6 (KM227012). Our study shows that domestic ruminants from China are not uncommonly infected with a variety of Anaplasma spp. and Ehrlichia spp.

No abstract

Quinolones are broad-spectrum antibiotics that have been used for decades in treating bacterial infections in humans and animals, and subsequently bacterial resistance to these agents has increased. While studies indicated the relationship between gyrA mutations and bacterial resistance to quinolones, CRISPR/Cas9 was used in this study to investigate causal role of gyrA mutation in the quinolone resistance. In this study, 818 clinical Escherichia coli isolates were analyzed for gyrA mutations and their resistance to quinolones. The CRISPR/Cas9 system was used to generate gyrA mutations in quinolone-susceptible E. coli ATCC 25922, and quinolone-resistant clinical E. coli. The antimicrobial resistance prevalence rate in E. coli against nalidixic acid, ciprofloxacin and enrofloxacin was 77.1% (631/818), 51.1% (418/818) and 49.8% (407/818), respectively. The gyrA mutations were identified in nucleotide positions 248, 255, 259, 260, 261, 273 and 300, and mutations at positions 248 and 259 resulting in amino acid changes at positions 83 and 87 were associated with quinolone resistance. Double-site amino acid mutations increase resistance to quinolones. The gyrA mutations causing changes at amino acids 83 and 87 reversed the features of quinolone resistance in ATCC and clinical strains, verifying the causal role of gyrA mutation in the quinolone resistance of E. coli.

Chlamydia trachomatis, Mycoplasma spp., Neisseria gonorrhoeae and Treponema pallidum are sexually transmitted pathogens that threaten reproductive health worldwide. In this study, vaginal swabs obtained from women (n = 133) that attended an infertility clinic in China were tested with qPCRs for C. trachomatis, Mycoplasma spp., N. gonorrhoeae, T. pallidum and tetracycline resistance genes. While none of vaginal swabs were positive for N. gonorrhoeae and T. pallidum, 18.8% (25/133) of the swabs were positive for Chlamydia spp. and 17.3% of the swabs (23/133) were positive for Mycoplasma species. All swabs tested were positive for tetracycline resistance gene tet(M) which is the most effective antibiotic for bacterial sexually transmitted infections. The qPCRs determined that the gene copy number per swab for tet(M) was 7.6 times as high as that of C. trachomatis 23S rRNA, and 14.7 times of Mycoplasma spp. 16S rRNA. In China, most hospitals do not detect C. trachomatis and Mycoplasma spp. in women with sexually transmitted infections and fertility problems. This study strongly suggests that C. trachomatis and Mycoplasma spp. should be routinely tested in women with sexually transmitted infections and infertility in China, and that antimicrobial resistance of these organisms should be monitored. Further studies are warranted to determine the prevalences in different regions and associated risk factors.