Streptococcus agalactiae isolated from clinical mastitis cases on large dairy farms in north China: phenotype, genotype of antimicrobial resistance and virulence genes

IF 4.6 2区医学 Q2 IMMUNOLOGY

Frontiers in Cellular and Infection Microbiology Pub Date : 2024-09-04 DOI:10.3389/fcimb.2024.1417299

Kai Liu, Xiang Liu, Jieyan Yang, Xiaolong Gu, Limei Zhang, Weijie Qu

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引用次数: 0

Abstract

Streptococcus agalactiae (Strep. agalactiae) is bovine mastitis pathogen and has thus became a matter of concern to dairy farms worldwide in terms of economic loss. The aims of this study were to (a) determine virulence genes, and (b) characterize the antimicrobial resistance (AMR) profiles and AMR genes and (c) figure out the relationship between AMR phenotypes and genotypes of Strep. agalactiae isolated from dairy cows in north China. A total of 20 virulence genes and 23 AMR genes of 140 isolates collected from 12 farms in six provinces were studied. The antimicrobial susceptibility of 10 veterinary commonly used antimicrobials were tested using the broth microdilution method. Results showed that all the isolates harbored the virulence genes lacIV, gapC, and dltA. The isolates that harbored the genes lacIII, fbsA, hylB, and cfb exhibited the high prevalence (99.29%), followed by isolates that harbored lacI (98.57%), bibA (97.86%), cylE (97.14%), lacII (92.14%), cspA (52.14%), pavA (25%), bca (2.14%), and scpB (0.71%). The fbsB, lmb, spbI, bac, and rib genes were not detected. The virulence patterns of B (fbsA_cfb_cylE_ hylB_bibA_cspA_ gapC_dltA_lacIII/IV) and C (fbsA_cfb_ bibA _ gapC_ dltA_lacIV) were dominant, accounting for 97.86% of the isolates. The following AMR genes were prevalent: pbp1A (97.14%), tet(M) (95.00%), lnu (A) (80.71%), erm (B) (75.00%), tet(O) (72.14%), blaZ (49.29%), tet(S) (29.29%), blaTEM (25.71%), erm (A) (17.14%), erm (C) (13.57%), tet (L) (10.71%), linB (2.86%), and erm (TR) (2.86%). The pbp2b, mecA1, mecC, lnu (D), erm (F/G/Q), and mef (A) genes were not detected. Eighty percent of the isolates harbored AMR genes and were highly resistant to tetracycline, followed by macrolides (10.71%), lincosamides (9.29%) and β-lactams (4.29%). In conclusion, isolates only exhibited well correlation between tetracyclines resistance phenotype and genotype, and almost all isolates harbored intact combination of virulence genes.

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从华北大型奶牛场临床乳腺炎病例中分离出的无乳链球菌：表型、抗菌药耐药性基因型和毒力基因

无乳链球菌（Strep. agalactiae）是牛乳腺炎病原体，因此已成为全球奶牛场关注的经济损失问题。本研究的目的是：（a）确定毒力基因；（b）描述抗菌药耐药性（AMR）特征和 AMR 基因；（c）弄清从中国北方奶牛中分离的无乳链球菌的 AMR 表型与基因型之间的关系。研究了从 6 个省 12 个牧场采集的 140 个分离株中的 20 个毒力基因和 23 个 AMR 基因。采用肉汤微稀释法检测了 10 种兽医常用抗菌药物的抗菌敏感性。结果表明，所有分离株都携带毒力基因 lacIV、gapC 和 dltA。携带lacIII、fbsA、hylB和cfb基因的分离物感染率最高（99.29%），其次是携带lacI（98.57%）、bibA（97.86%）、cylE（97.14%）、lacII（92.14%）、cspA（52.14%）、pavA（25%）、bca（2.14%）和scpB（0.71%）基因的分离物。未检测到 fbsB、lmb、spbI、bac 和 rib 基因。B 型（fbsA_cfb_cylE_hylB_bibA_cspA_ gapC_dltA_lacIII/IV）和 C 型（fbsA_cfb_bibA _ gapC_ dltA_lacIV）的毒力模式占优势，占分离株的 97.86%。以下 AMR 基因普遍存在：pbp1A（97.14%）、tet（M）（95.00%）、lnu（A）（80.71%）、erm（B）（75.00%）、tet（O）（72.14%）、blaZ（49.29%）、tet（S）（29.29%）、blaTEM（25.71%）、erm（A）（17.14%）、erm（C）（13.57%）、tet（L）（10.71%）、linB（2.86%）和erm（TR）（2.86%）。未检测到 pbp2b、mecA1、mecC、lnu (D)、erm (F/G/Q) 和 mef (A) 基因。80%的分离物携带 AMR 基因，对四环素高度耐药，其次是大环内酯类（10.71%）、林可霉素类（9.29%）和β-内酰胺类（4.29%）。总之，分离物的四环素耐药表型与基因型之间只有很好的相关性，几乎所有分离物都携带完整的毒力基因组合。

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来源期刊

Frontiers in Cellular and Infection Microbiology IMMUNOLOGY-MICROBIOLOGY

CiteScore

7.90

自引率

7.00%

发文量

1817

审稿时长

14 weeks

期刊介绍： Frontiers in Cellular and Infection Microbiology is a leading specialty journal, publishing rigorously peer-reviewed research across all pathogenic microorganisms and their interaction with their hosts. Chief Editor Yousef Abu Kwaik, University of Louisville is supported by an outstanding Editorial Board of international experts. This multidisciplinary open-access journal is at the forefront of disseminating and communicating scientific knowledge and impactful discoveries to researchers, academics, clinicians and the public worldwide. Frontiers in Cellular and Infection Microbiology includes research on bacteria, fungi, parasites, viruses, endosymbionts, prions and all microbial pathogens as well as the microbiota and its effect on health and disease in various hosts. The research approaches include molecular microbiology, cellular microbiology, gene regulation, proteomics, signal transduction, pathogenic evolution, genomics, structural biology, and virulence factors as well as model hosts. Areas of research to counteract infectious agents by the host include the host innate and adaptive immune responses as well as metabolic restrictions to various pathogenic microorganisms, vaccine design and development against various pathogenic microorganisms, and the mechanisms of antibiotic resistance and its countermeasures.