Molecular epidemiology, characterization of virulence factors and antibiotic resistance profile of Streptococcus agalactiae isolated from dairy farms in China and Pakistan  

作　　者：Ambreen LEGHARI Shakeel Ahmed LAKHO Faiz Muhammad KHAND Khaliq ur Rehman BHUTTO Sameen Qayoom LONE Muhammad Tahir ALEEM Iqra BANO Muhammad Ali CHANDIO Jan Muhammad SHAH LIN Hui-xing FAN Hong-jie 

机构地区：[1]MOE Joint International Research Laboratory of Animal Health and Food Safety,College of Veterinary Medicine,Nanjing Agricultural University,Nanjing 210095,P.R.China [2]Shaheed Benazir Bhutto University of Veterinary and Animal Sciences,Sakrand 67210,Pakistan [3]Central Veterinary Diagnostic Laboratory,Tando Jam 70050,Pakistan [4]Jiangsu Co-innovation Center for the Prevention and Control of Important Animal Infectious Diseases and Zoonoses,Yangzhou University,Yangzhou 225009,P.R.China

出　　处：《Journal of Integrative Agriculture》2023年第5期1514-1528,共15页农业科学学报（英文版）

基　　金：supported by the National Key Research and Development Program of China (2021YFD1800400);the National Natural Science Foundation of China (31872480);the Jiangsu Agriculture Science and Technology Innovation Fund of China (CX(19)2020);the Priority Academic Program Development of Jiangsu Higher Education Institutions, China (PAPD)。

摘　　要：Streptococcus agalactiae is one of the most common pathogens that cause bovine mastitis worldwide. Identifying pathogen prevalence and virulence factors is critical for developing prevention and control approaches. Herein, 1 161 milk samples from various dairy farms in China(n=558) and Pakistan(n=603) were collected between 2019–2021 and were subjected to S. agalactiae isolation. Prevalence, serotyping, virulence genes, and antibiotic-resistant genes of S. agalactiae were evaluated by PCR assay. All isolates were characterized for haemolysis, biofilm production, cytotoxicity, adhesion, and invasion on bovine mammary epithelial cells. The prevalence of S. agalactiae-induced mastitis in cattle was found to be considerably higher in Pakistan than in China. Jiangsu and Sindh provinces had the highest area-wise prevalence in China and Pakistan, respectively. Serotypes Ia and II were prevalent in both countries, whereas serotype III was found only in Pakistan. Moreover, all isolates tested positive for PI-2b gene but negative for PI-1 and PI-2a genes. All isolates harboured cfb, cylE, hylB, and fbsB virulent genes, whereas many of them lacked bibA, rib and bca. However, the absence of bac and scp genes in Chinese isolates and cspA in Pakistani isolates was noted, while spb1 and lmb were not detected in isolates of both countries. Pakistani isolates, particularly serotype Iapositive, had a considerably higher ability to produce biofilm, haemolysis, cytotoxicity, adhesion, and invasion than Chinese isolates. Most of the isolates were phenotypically resistant to tetracycline, erythromycin, and clindamycin and genotypic resistance was confirmed by the presence of ermA, ermB, tetM and tetO genes. Our study highlights the antimicrobial resistance profile and virulence-related factors contributing to the epidemiological spread of mastitis-causing S. agalactiae in China and Pakistan. The findings may facilitate future studies designed to develop improved treatment and control strategies against this pathogen.

关 键 词：STREPTOCOCCUS AGALACTIAE MASTITIS EPIDEMIOLOGY VIRULENCE CHARACTERIZATION antibiotic resistance 

分 类 号：S858.23[农业科学—临床兽医学]