Detection of methicillin resistant and slime factor production of coagulase negative Staphylococcus spp. in bovine clinical mastitis by using PCR

Abstract

This study aims to investigate the slime production of Coagulase negative staphylococci (CoNS) isolates by phenotypic method on Congo Red Agar plates (CRA) and Genotypic detection of icaA, icaD and mecA genes by polymerase chain reaction (PCR). Out of 105 milk samples obtained from clinical bovine mastitis, 101samples (96.2%) were positive for bacterial growth. CoNS isolates was detected in 20 isolates with a percentage of 19.8%. Their ability to form biofilm as one of the most important virulence factors of the organisms using Congo Red Agar (CRA) method was investigated in which 13 out of 17 CoNS isolates (76.47%) were found to be slime producers. By PCR, mecA gene was found in threeout of 6 CoNS isolates (50%). Also six (100%) and three (50%) isolates were positive for icaA gene and icaD gene, respectively. In addition one isolate out of the six CoNS isolates (16.67%) was positive for the presence of icaA, icaD and mecA genes and also has the ability to form biofilm. The in vitro activities of CoNS against 11 selected antimicrobial agents referred that the highest resistance rate of CoNS observed to Lincomycin (100%), followed by Cefotaxime (94.41%), Oxacillin (58.82%), Ampicillin (47.06%) and Penicillin (41.18%), while the highest rate of sensitivity observed to Enrofloxacin and Gentamicin (100%, for each), followed by Doxycycline (94.11%).Conclusion, the findings of the present study demonstrated the ability of CoNS isolated from bovine clinical mastitis to form biofilms. This must be considered as an alarming situation, and so attention must be paid toward implementation of new ways for effective prophylaxis, control, and treatment of such infections in the dairy farms. The prudent use of antibiotics and rapid and continuous screening for resistant microorganisms should be more focused to prevent the emergence and spread methicillin resistant coagulase negative staphylococci, because these strains can cause severe damage to infected sites and may be widespread in the environment.