Klebsiella pneumoniae (K. pneumoniae) is an opportunistic pathogen, which causes serious infections in humans and animals. To investigate the antimicrobial resistance pattern and virulence profile of K. pneumoniae, a total of 887 samples were collected from both the healthy and mastitis cows and the bedding, feed, feces, air, drinking water, spraying water, washing water, and milk cup swabs from five dairy farms in Hubei, China, during 2019 and 2020. K. pneumoniae was isolated and identified using PCR of the khe and 16S rDNA sequencing. A genotypic characterization was performed for K. pneumoniae isolates using wzi typing and multilocus sequence typing (MLST). Antimicrobial resistances were confirmed using broth microdilution against 17 antimicrobial agents and resistance and virulence genes were determined by PCR. The prevalence of K. pneumoniae was 26.94% (239/887) distributed in 101 wzi allele types (199/239, 83.26%) and 100 sequence types (STs) (209/239, 87.45%), including 5 new wzi allele type and 25 new STs. Phylogenetic analysis showed that K. pneumoniae isolated from milk, nipple swab, feed, and feces is classified in the same clone complex. By comparing with the PubMLST database, at least 67 STs have the risk of spreading in different species and regions. Interestingly, 60 STs have been isolated from humans. The isolates were highly sensitive to meropenem and colistin, but resistant to ampicillin (100%), sulfisoxazole (94.56%), cephalothin (47.28%), streptomycin (30.13%), and so on. Noteworthy, multidrug-resistant (MDR) rate was found to be 43.93% in this study. By PCR, 30 of 68 antimicrobial resistance (AMR) genes were identified; the prevalence rate of blaTEM, blaSHV, strA, strB, aadA1, and aac(6′)-Ib-cr was more than 50%. Eleven CTX-M-producing K. pneumoniae were found. The detection rate of fimH, mrkD, uge, wabG, entB, iutA, iroN, and ureA was over 85%. This study reinforces the epidemiological importance of K. pneumoniae in food-producing animals in Hubei. The emergence and spread of environmental MDR K. pneumoniae may pose a potential threat to food safety and public health.

产气荚膜梭菌是一种食源性致病菌,可存在于外界环境和健康家禽等动物的肠道中,在家禽肠道中增殖后可引起坏死性肠炎等疾病,对全世界的肉鸡和火鸡产业造成严重损害.此外,产气荚膜梭菌还可引起人类食物中毒、伤口的气性坏疽等疾病,危害人类健康.养殖业通常采用在饲料中添加抗生素的方法预防鸡坏死性肠炎,但自2017年开始的"减抗禁抗"政策的实施必然对临床细菌耐药性产生很大的影响,因此有必要了解当前鸡源产气荚膜梭菌的耐药情况.本文结合目前鸡产气荚膜梭菌的耐药现状、耐药基因检测和预防措施展开讨论,为养殖业合理用药控制其耐药性的产生和传播提供参考.

利用调查和数据统计报道我国近年来的兽用抗生素使用、养殖业用药背景、抗菌药物耐药、动物源细菌耐药性监测、动物源细菌耐药监测数据库研究及国家制定的相关政策等现状,并针对我国动物源细菌的耐药和监测现状,提出了我国政府与各地区相关部门应科学评估分析动物源细菌耐药性监测数据及变化趋势;借鉴发达国家的经验和方法,完善我国动物源细菌耐药性监测网络和监测体系;加强教育和宣传等应对措施,为解决全球动物源细菌耐药性问题作出贡献.

Bacterial resistance is a complex scientific issue. To manage this issue, we need to deeply understand the influencing factors and mechanisms. Based on the background of livestock husbandry, this paper reviews the factors that affect the acquisition of bacterial resistance. Meanwhile, the resistance mechanism is also discussed. “Survival of the fittest” is the result of genetic plasticity of bacterial pathogens, which brings about specific response, such as producing adaptive mutation, gaining genetic material or changing gene expression. To a large extent, bacterial populations acquire resistance genes directly caused by the selective pressure of antibiotics. However, mobile resistance genes may be co-selected by other existing substances (such as heavy metals and biocides) without direct selection pressure from antibiotics. This is because the same mobile genetic elements as antibiotic resistance genes can be co-located by the resistance determinants of some of these compounds. Furthermore, environmental factors are a source of resistance gene acquisition. Here, we describe some of the key measures that should be taken to mitigate the risk of antibiotic resistance. We call on the relevant governments or organizations around the world to formulate and improve the monitoring policies of antibiotic resistance, strengthen the supervision, strengthen the international cooperation and exchange, and curb the emergence and spread of drug-resistant strains.

qnrS是质粒介导的喹诺酮类药物的耐药基因,通过保护DNA回旋酶活性从而降低宿主菌对喹诺酮类药物的敏感性.这种保护作用依赖于qnrS基因的表达水平,同时,qnrS的表达主要受喹诺酮类药物浓度的影响,且σ-D调控因子(regulator of sigma D,Rsd)也参与该基因的表达调控.qnrS基因在沙门氏菌中高度流行,并且是大肠埃希氏菌中质粒介导的喹诺酮类耐药基因的优势基因.qnrS可以在细菌间进行传播,或与其他耐药基因共存于同一质粒上发生共转移,从而导致多重耐药的发生.论文对qnrS基因的发现、表达及其调控机制、在沙门氏菌和大肠埃希氏菌中的流行及传播的研究进展进行综述,以期为控制qnrS基因介导的耐药性提供参考.

Background: Salmonella enterica is one of the common pathogens in both humans and animals that causes salmonellosis and threatens public health all over the world. Methods and Results: Here we determined the virulence phenotypes of nine Salmonella enterica subsp. enterica (S. enterica) isolates in vitro and in vivo, including pathogenicity to chicken, cell infection, biofilm formation and virulence gene expressions. S. Enteritidis 211 (SE211) was highly pathogenic with notable virulence features among the nine isolates. The combination of multiple virulence genes contributed to the conferring of the high virulence in SE211. Importantly, many mobile genetic elements (MGEs) were found in the genome sequence of SE211, including a virulence plasmid, genomic islands, and prophage regions. The MGEs and CRISPR-Cas system might function synergistically for gene transfer and immune defense. In addition, the neighbor joining tree and the minimum spanning tree were constructed in this study. Conclusions: This study provided both the virulence phenotypes and genomic features, which might contribute to the understanding of bacterial virulence mechanisms in Salmonella enterica subsp. enterica. The first completed genomic sequence for the high virulent S. Enteritidis isolate SE211 and the comparative genomics and phylogenetic analyses provided a preliminary understanding of S. enterica genetics and laid the foundation for further study.

The purpose of this study was to investigate the changes of resistance phenotype and plasmid-mediated quinolone resistance genes (PMQRs) in Escherichia coli (E. coli) during enrofloxacin (ENR) administration in different breeding cycles. In 2020, 983 strains of E. coli were isolated from different samples in different cycles at the broiler farm with the largest single batch of slaughter capacity in Hebei Province, China. All samples were from chicken, environmental, and human sources. The sensitivity of the isolates to various antibiotics was determined by broth microdilution method. The findings of this study include: (1) the total isolation rate of E. coli in the four cycles was 63.83% (983/1540); (2) the average resistance rate of E. coli from 1-day-old chickens to enrofloxacin was as high as 75% in each cycle, and with the use of enrofloxacin, the resistance rate of E. coli from chickens gradually increased to 100%; (3) 107 strains of E. coli randomly selected from different cycles and sources demonstrated the multi-drug resistance phenotypes. The highest resistance rate was doxycycline (100%), and the lowest was erythromycin (54.21%); (4) the detection rate of PMQRs of E. coli from chickens in different cycles were always higher than that from environmental and human. In particular, the PMQRs pollution rate of chicken seedlings in each cycle were generally higher than that of other sources; (5) We used SPSS software to analyze the Kendall rank correlation of the experimental data. The resistance of E. coli isolated from this farm to ciprofloxacin (CIP) may increase along with the increase of resistance to enrofloxacin (Kendall’s tau-b = 0.190, p = 0.021). All these data highlight the serious problem of bacterial resistance in this farm. Therefore, it is urgent to provide guidance for the prevention and control of colibacillosis and drug resistance in this farm.

动物疼痛和炎症可影响其健康状况、养殖场经济效益等,预防和治疗动物疼痛、炎症具有重要意义.非甾体抗炎药可以减少动物疼痛和炎症的发生.近几年对非甾体抗炎药在动物中的应用研究越来越多,同时非甾体抗炎药的一些新功能被发现.论文对兽医常用非甾体抗炎药物的应用研究进展做一综述,以期为非甾体抗炎药在动物中的合理使用以及进一步研究提供参考.

Salmonella is recognized as one of the most common microbial pathogens worldwide. The bacterium contains the clustered regularly interspaced short palindromic repeats (CRISPR)-CRISPR-associated (Cas) systems, providing adaptive immunity against invading foreign nucleic acids. Previous studies suggested that certain bacteria employ the Cas proteins of CRISPR-Cas systems to target their own genes, which also alters the virulence during invasion of mammals. However, whether CRISPR-Cas systems in Salmonella have similar functions during bacterial invasion of host cells remains unknown. Here, we systematically analyzed the genes that are regulated by Cas3 in a type I-E CRISPR-Cas system and the virulence changes due to the deletion of cas3 in Salmonella enterica serovar Enteritidis. Compared to the cas3 gene wild-type (cas3 WT) Salmonella strain, cas3 deletion upregulated the lsrFGBE genes in lsr (luxS regulated) operon related to quorum sensing (QS) and downregulated biofilm-forming-related genes and Salmonella pathogenicity island 1 (SPI-1) genes related to the type three secretion system (T3SS). Consistently, the biofilm formation ability was downregulated in the cas3 deletion mutant (Δcas3). The bacterial invasive and intracellular capacity of Δcas3 to host cells was also reduced, thereby increasing the survival of infected host cells and live chickens. By the transcriptome-wide screen (RNA-Seq), we found that the cas3 gene impacts a series of genes related to QS, the flagellum, and SPI-1-T3SS system, thereby altering the virulence phenotypes. As QS SPI-1-T3SS and CRISPR-Cas systems are widely distributed in the bacteria kingdom, our findings extend our understanding of virulence regulation and pathogenicity in mammalian hosts for Salmonella and potentially other bacteria.

欧盟考虑到抗生素耐药性的发展和抗生素耐药基因可能从动物到人微生物的转移,决定从2006年1月1日起禁止抗生素作为生长促进剂,甚至还建议禁止在动物饲料中全面使用所有的抗菌剂.收集和整理欧盟饲料药物添加剂的禁用清单和法规,介绍欧盟禁用饲料药物添加剂的历史及其对动物健康的影响,以期为中国饲料药物添加剂的使用和管理提供借鉴和参考.

欧盟允许在饲料和饮水中添加抗菌药和抗球虫药治疗、预防和防治动物疾病.本文收集和整理了欧盟常见的准用饲料药物添加剂清单,说明其适应症和用法用量,并对其授权程序和使用等管理现状进行简单概述,为中国饲料药物添加剂的使用和管理提供借鉴和参考.