2014—2015年北京市批发市场肉类食品中沙门菌表型和基因组特征分析

Phenotypic and genomic characterization for Salmonella isolates recovered from meat products in Beijing wholesale markets,2014-2015

目的分析北京批发市场肉类食品中沙门菌的表型和基因组特征。方法对分离自北京市批发市场的336株肉类食品来源沙门菌,采用微量肉汤稀释法对25种抗菌药物进行耐药性测试,开展全基因组测序并使用SeqSero2、SISTR软件分析血清型和ST型,使用Abricate软件的CARD、VFDB模块预测菌株的耐药基因和毒力因子,使用沙门菌分子血清分型试剂盒和血清凝集法验证部分疑难菌株血清型。结果336株沙门菌菌株对萘啶酸、氨苄西林的耐药率分别为62.5%(210/336)和55.1%(185/336),对替加环素、头孢西丁和碳青霉烯类抗菌药物均敏感;207株(61.6%,207/336)为多重耐药株,最高可同时耐受10类药物,最常见耐药谱为NAL-AMP-SAM。共检出24种血清型,主要型别为肠炎(34.5%,116/336)、德尔卑(17.3%,58/336)和印第安纳(10.4%,35/336);共检出27种ST型,主要型别为ST11,ST型与血清型较为相符。氨基糖苷类、氟喹诺酮类、β-内酰胺类、磺胺类、四环素类耐药基因的携带率均超过48%,耐药基因预测与耐药表型结果一致性较高;共预测出122种毒力基因,其中74种携带率达100%。结论北京市批发市场肉类食品中沙门菌中多重耐药比例较高、耐药谱复杂,血清型和ST型种类多样,耐药基因和毒力基因携带率较高,耐药表型和基因型较为一致。

Objective To analyze the phenotypic and genomic characteristics of Salmonella isolates recovered from meat products in Beijing wholesale markets.Methods A total of 336 Salmonella strains from meat products collected from wholesale markets in Beijing were tested for antimicrobial resistance to 25 antimicrobial compounds by micro-broth dilution method;whole genome data were sequenced,followed by the serotype and ST type prediction by Seqsero2 and SISTR software,and the drug resistance genes and virulence factors were also predicted with CARD and VFDB databases of Abricate software;Salmonella serotyping assay kit and serum agglutination method were used for serotype confirmation of some isolates with different genome prediction results.Results The resistance rates to Nalidixic acid and Ampicillin were 62.5%(210/336)and 55.1%(185/336),respectively,and all isolates were susceptible to Tigecyclin,Cefoxitin and Carbapenem antimicrobial compounds;207 isolates(61.6%,207/336)were multi-drug resistant,some could even be resistant to ten categories of drugs at the same time,and the most common antimicrobial resistance spectrum was NAL-AMP-SAM.A total of 24 serotypes were detected with predominant serotypes of Enteritidis(34.5%,116/336),Derby(17.3%,58/336)and Indiana(10.4%,35/336).A total of 27 ST types were detected,the dominant type was ST11;ST types were in good consistency with serotypes;The detection rates of resistant genes referred to aminoglycosides,fluoroquinolones,β-lactams,sulfonamides and tetracyclines are more than 48%,and the first two reached 100%.The prediction of drug resistance genes was consistent with the results of antimicrobial resistance phenotype.A total of 122 virulence genes were predicted,74 of which existing among all isolates.Conclusion Salmonella in meat from the wholesale markets of Beijing has a high proportion of multiple drug resistance,a complex drug resistance spectrum,a variety of serotypes and ST types,and a high carrying rate of drug resistance gene and virulence gene;drug resistance phenotype and genotype are relatively consistent.