title: Antimicrobial susceptibility, virulence genes, and randomly amplified polymorphic DNA analysis of Staphylococcus aureus recovered from bovine mastitis in Ningxia, China.
abstract: Staphylococcus aureusis the leading pathogen involved inbovine mastitis, but knowledgeabout antimicrobial resistance, virulence factors, and genotypes of Staphylococcus aureus resulting in bovine mastitis in Ningxia, China, is limited. Therefore, antimicrobial susceptibility, virulence gene, and randomly amplified polymorphic DNA (RAPD) analyses of Staph. aureus were carried out. A total of 327 milk samples from cows with clinical and subclinical mastitis in 4 regions of Ningxia were used for the isolation and identification of pathogens according to phenotypic and molecular characteristics. Antimicrobial susceptibility against 22 antimicrobial agents was determined by disk diffusion. The presence of 8 virulence genes in Staph. aureus isolates was tested by PCR. Genotypes of isolates were investigated based on RAPD. Results showed that 35 isolates obtained from mastitis milk samples were identified as Staph. aureus. The isolates were resistant to sulfamethoxazole (100%), penicillin G (94.3%), ampicillin (94.3%), erythromycin (68.6%), azithromycin (68.6%), clindamycin (25.7%), amoxicillin (11.4%), and tetracycline (5.7%). All of the isolates contained one or more virulence genes with average (standard deviation) of 6.6±1.6. The most prevalent virulence genes were hlb (97.1%), followed by fnbpA, hla, coa (94.3% each), nuc (85.7%), fnbpB (80%), clfA (77.1%), and tsst-1 (40%). Nine different gene patterns were found and 3 of them were the dominant gene combinations (77.1%). Staphylococcus aureus isolates (n=35) were divided into 6 genotypes by RAPD tying, the genotypes III and VI were the most prevalent genotypes. There was greatvariation in genotypes of Staph. aureus isolates, not only among different farms, but also within the same herd in Ningxia province. The study showed a high incidence of Staph. aureus with genomic variation of resistance genes, which is matter of great concern in public and animal health in Ningxia province of China.
authors: College of Life Science, Ningxia University, Yinchuan Ningxia 750021, China.
authors: Dong
authors: D
authors: Wang
authors: College of Veterinary Medicine, China Agricultural University, Beijing 100193, China.
authors: Limei
authors: L
authors: Zhang
authors: College of Life Science, Ningxia University, Yinchuan Ningxia 750021, China.
authors: Xuezhang
authors: X
authors: Zhou
authors: College of Life Science, Zhejiang Sci-Tech University, Hangzhou, Zhejiang 310018, China.
authors: Yulong
authors: Y
authors: He
authors: Animal Disease Prevention and Control Center of Shapotou District, Zhongwei, Ningxia 755000, China.
authors: Changfu
authors: C
authors: Yong
authors: Agriculture and Animal Husbandry Bureau of Shizuishan, Shizuishan, Ningxia 753000, China.
authors: Mingliang
authors: M
authors: Shen
authors: Magyar Tudományos Akadémia-Szent István Egyetem Large Animal Research Group, Üllő - Dóra major, H-2225 Hungary.
authors: Otto
authors: O
authors: Szenci
authors: College of Veterinary Medicine, China Agricultural University, Beijing 100193, China. Electronic address: hanbo@cau.edu.cn.
authors: Bo
authors: B
authors: Han
mesh_terms: D000818:Animals; D000890:Anti-Infective Agents; D002417:Cattle; D004247:DNA; D005260:Female; D008414:Mastitis, Bovine / Q000382:microbiology*; D008826:Microbial Sensitivity Tests / Q000662:veterinary; D008892:Milk; D019105:Random Amplified Polymorphic DNA Technique; D013203:Staphylococcal Infections / Q000662:veterinary; D013211:Staphylococcus aureus / Q000302:isolation & purification*; D014774:Virulence
chemical_list: D000890:Anti-Infective Agents; D004247:DNA
keywords: RAPD genotype; Staphylococcus aureus; antimicrobial susceptibility; bovine mastitis; virulence gene