Phenotypic and Genetic Antibiogram of Methicillin-Resistant Staphylococci Isolated from Bovine Mastitis in Korea

Abstract

Staphylococcus aureus belongs to the group of major contagious mastitis pathogens, whereas the coagulase-negative staphylococci (CNS) are also capable of causing opportunistic bovine mastitis. Many of these strains are resistant to penicillin or ampicillin because of the long-term use of beta-lactam antibiotics in agricultural and healthcare settings. Based on the simple and highly specific coagulase genotyping by PCR-RFLP used for discriminating among Staph. aureus strains, the relationship between phenotypic antibiogram and the polymorphism of coagulase gene was determined in this study. The staphylococci strains (835 Staph. aureus and 763 CNS) were isolated from 3,047 bovine mastitic milk samples from 153 dairy farms in 8 provinces from 1997 to 2004 in the Republic of Korea. Twenty-one (2.5%) Staph. aureus and 19 (2.4%) CNS strains were resistant to methicillin [oxacillin minimum inhibitory concentration (MIC) > or = 4 microg/mL]. The mecA gene was also found in 13 methicillin-resistant Staph. aureus (MRSA) and 12 methicillin-resistant CNS (MRCNS) isolates with a significantly higher detection rate of the mecA gene in MRSA with high MIC (> or = 16 microg/mL) compared with those with MIC < or = 8 microg/mL. Methicillin-resistant Staph. aureus and MRCNS were also more resistant to other antibiotics (ampicillin, cephalothin, kanamycin, and gentamicin) than methicillin-susceptible staphylococci. Among 10 different coa PCR-RFLP patterns (A to J) in 706 Staph. aureus strains, the main types were A (26.9%), B (17.0%), G (10.5%), and H (15.4%), with the frequent observation of the A and H types (6 and 10 isolates) in MRSA. This study indicates that major epidemic Staph. aureus clones may be spread between different dairy farms, and the profile of coa genotype can be applied for epidemiological investigations and control of bovine mastitis, particularly one caused by MRSA with specific prevalent coa types.

Isolation, Identification and Antimicrobial Resistance Profile of Staphylococcus aureus and Occurrence of Methicillin Resistant S. aureus Isolated from Mastitic Lactating Cows in and around Assosa Town, Benishangul Gumuz Region, Ethiopia

“…ß-lactam antibiotics are the most frequently used in intramammary infusion therapy. Bacterial resistance mechanisms to this class of antibiotics include production of ß-lactamase and low-affinity penicillin-binding protein 2a (PBP 2a) determined by the presence of the chromosomal gene mecA [6].…”

Correlation Between the Genotype Detection Determined by Rt- PCR Assays and the Phenotypic Detection Determined by Antibiotic Susceptibility Patterns of Methicillin-Resistant Staphylococcus Aureus Clinicalisolates in Algeria.

“…Res. 5(5), 950-955 951 Since then, the resistance rate of methicillin-resistant S. aureus (MRSA) has gradually increased and become a serious problem in both community and hospital infections worldwide in 1970 [12]. Until the mid-1990s, the majority of MRSA isolates exhibited multiple resistance to several antimicrobial agents including tetracyclines, aminoglycosides, macrolides, lincosamides and fluoroquinolones [5,12,15,16].…”

Resistência bacteriana e ação das bacteriocinas de Lactobacillus spp em Staphylococcus aureus isolados de mastite bovina

“…Vários trabalhos vêm relatando a disseminação de cepas resistentes, nas quais a produção de β -lactamases e modificação das PBPs são os mais importantes mecanismos descritos (Aarestrup et al 2001). A produção da PBP2a, proteína de ligação à penicilina de baixa afinidade, é determinada pela presença do gene mecA (Moon et al 2007 O procedimento de isolamento e identificação foi desenvolvido segundo Koneman et al (2008). As amostras foram inoculadas em ágar-sangue de carneiro a 5%.…”

“…A transmissão desses genes pode envolver tanto espécies patogênicas como membros da microbiota indígena dos hospedeiros. O gene mecA induz resistência à oxacilina e, também, acarreta falhas terapêuticas quando outros ß-lactâmicos ou outras classes de antibióticos são utilizadas (Moon et al, 2007 …”