Data correlating b-lactamases found in commensal Escherichia coli of human and animal origin are limited. In this study, 447 commensal E. coli isolates from the faeces of humans and swine (280 human isolates from four hospitals and 167 swine isolates from seven farms) were collected between September 2006 and January 2009 in western China. For extended-spectrum b-lactamase (ESBL)-producing and other cephalosporin-resistant isolates, the relevant b-lactamase genes (bla TEM , bla SHV , bla CTX-M-1/2/9 group, bla CMY-2 and bla KPC ) were detected by PCR analysis. Of the 447 isolates tested, 120 (26.8 %) were confirmed as producing ESBL. Among these, 70 and 40 human isolates carried a member of the bla CTX-M-1 group (13 bla CTX-M-3 , 21 bla CTX-M-15 , four bla CTX-M-22 , eight bla CTX-M-28 , four bla CTX-M-36 , 15 bla CTX-M-55 and five bla CTX-M-69 ) or bla SHV (14 bla SHV-2 , seven bla SHV-5 , ten bla SHV-12 , five bla SHV-57 and four bla SHV-97 ), respectively, whilst six and four swine isolates carried a member of the bla CTX-M-1 group (one bla CTX-M-15 and five bla CTX-M-22 ) or bla SHV (three bla SHV-2 and one bla SHV-12 ), respectively. Furthermore, 59 human and swine isolates and seven human isolates carried bla CMY-2 and bla KPC , respectively. These findings indicate that the bla CTX-M-1 group, including the novel variant bla CTX-M-69 , and bla SHV are the predominant ESBL genes in both humans and swine in western China, and bla CMY-2 is also common in both groups. The carriage rates of broad-spectrum b-lactamases among commensal E. coli was much lower in swine than in humans, suggesting that b-lactamase genes have not established themselves in animal ecosystems in western China.

Avian infectious bronchitis is an acute, highly contagious disease of chickens. To study the differences of dynamic distribution between nephropathogenic infectious bronchitis virus (IBV) strains such as SAIBK and other strains (the M41 and H120 strains), relative quantitative real-time reverse transcription-polymerase chain reaction was developed by housekeeping gene selection. Glyceraldehyde-3-phosphate dehydrogenase and Ubiquitin were chosen for normalization in this experimental set. Then nine tissues, the trachea, thymus, liver, spleen, lungs, kidney, pancreas, proventriculus, and bursa of Fabricius, were analyzed and compared to determine the tropism of IBV infection. In this research, the kidney and the lung were established of the most sensitive organs in IBV infection. The pancreas and the liver are candidates for antigen detection. The trachea and the spleen can be used as references for histological diagnosis, but they are not suitable for antigen detection; proventriculus might be an important target in IBV infection; the thymus and the bursa of Fabricius were not sensitive organs in IBV infection.

Four different Salmonella genomic island 1 (SGI1) variants, including two novel variants, were characterized in one Salmonella enterica serovar Rissen sequence type ST1917 isolate and three Proteus mirabilis isolates from swine farms in China. One novel variant was derived from SGI1-B with the backbone gene S021 disrupted by a 12.72-kb IS26 composite transposon containing the dfrA17-aadA5 cassettes and macrolide inactivation gene cluster mphA-mrx-mphR. The other one was an integron-free SGI1 and contained a 183-bp truncated S025 next to IS6100 and S044. Salmonella enterica is a zoonotic pathogen and is one of the primary causes of human infections worldwide. Salmonella genomic island 1 (SGI1) is an integrative 42.4-kb chromosomal element first identified in the multidrug resistance (MDR) S. enterica serovar Typhimurium phage type DT104 clone that has been epidemic among humans and domestic animals since the 1990s (1, 2). The MDR region in SGI1 is a complex In4-type class 1 integron (named In104) clustering five antibiotic resistance genes that confer resistance to ampicillin, chloramphenicol and florfenicol, streptomycin and spectinomycin, sulfonamides, and tetracycline (3). SGI1 was unexpectedly detected in a Proteus mirabilis clinical isolate in 2007 (4). Sequence analysis showed that SGI1 in S. enterica and P. mirabilis had the same chromosomal integration site, corresponding to the last 18 bp of the 3= end of the trmE (also named thdF) gene (5). It has been confirmed that SGI1 in S. enterica could be transferred by conjugation with the help of the IncA/C plasmid (6, 7).Many SGI1 variants result from the homologous recombination of gene cassettes within the MDR regions (3,(8)(9)(10)(11). A few variations in the SGI1 backbone are also described due to deletion, insertion, and transposition (3,9,10,(12)(13)(14)(15). Furthermore, several novel resistance genes, including the extended-spectrum ␤-lactamase (ESBL) gene bla VEB-6 and the fluoroquinolone resistance genes qnrA1 and qnrB2, have been reported in SGI1 (9, 11), suggesting that SGI1 could act as a mobilizable element to disseminate the critical resistance genes. In the present study, we characterized SGI1 among S. enterica and P. mirabilis isolates from swine farms in China.A total of 24 S. enterica and 61 P. mirabilis strains were isolated from samples of swine stools and diseased tissues in 35 swine farms from 16 provinces in China between May 2012 and February 2014. Antimicrobial susceptibility testing was performed by the disc diffusion method according to the CLSI guidelines (16). Primers used in this study are listed in Table S1 in the supplemental material. The left and right junctions of SGI1 were detected in one S. enterica serovar Rissen and three P. mirabilis strains. The multiple locus sequence typing for SGI1-containing S. Rissen strain Z4 showed that the types of the seven housekeeping genes, not reported to date, were 92 (aroC), 137 (dnaN), 8 (hemD), 524 (hisD), 206 (purE), 313 (sucA), and 330 (thrA). It was submitted to the website