Genotypic characterization of mecA gene and antibiogram profile of coagulase-negative staphylococci in subclinical mastitic cows

Abstract

Background and Aim: Coagulase-negative staphylococci (CNS) are becoming the major cause of clinical and subclinical bovine mastitis around the world. This study aims to estimate the prevalence, antibiogram, and frequency of the methicillinresistant (MR) (mecA) gene in CNS collected from cows with subclinical mastitis.Materials and Methods: Thirty-four milk samples were collected from 20 cows. Fifteen subclinical mastitis samples (~44.12%) were identified as CNS isolates. The Vitek2 compact system method was employed for the identification of the species. Furthermore, antibiotic sensitivity tests were performed against 10 different antibiotics for CNS strains. The mecA gene from isolated CNS was detected by conventional polymerase chain reaction (PCR).Results: Staphylococcus haemolyticus was the most predominant isolated species with an incidence of 33.3% (5/15 isolates), followed by 26.7% for Staphylococcus sciuri and Staphylococcus vitamins (4/15 isolates), and 13.3% for Staphylococcus vitulinus (2/15 isolates), respectively. The highest resistance rates were determined to be 40% (6/15 isolates) against penicillin and oxacillin (OX), 33.3% (5/15 isolates) against clindamycin, 13% (2/15 isolates) against chloramphenicol, amoxicillin, and erythromycin, and 5% (1/15 isolates) against ciprofloxacin, respectively. The results revealed that the isolates were resistant to one or more antimicrobial agents, with five isolates displaying multiple antimicrobial resistance. Furthermore, the results exhibit that all CNS isolates had the mecA gene at 310 bp with a 100% frequency. Moreover, for detecting MR isolates, there are significant discrepancies between phenotypic and genotypic approaches, and only 6/15 CNS isolates phenotypically demonstrated OX resistance. Conclusion:The results emphasize the necessity of frequent monitoring of phenotypic and genotypic profiles of CNS isolates to ensure effective control measures and the prevention of multidrug resistance strain evolution.

Molecular characterisation of antimicrobial resistance in coagulase negative staphylococci isolated from bovine subclinical mastitis

“…The most likely explanation was that MRS susceptibility testing using standard microbiological techniques was difficult because the phenotypic expression of resistance depends largely on growth conditions (like osmolarity and medium temperature) (Ibrahim et al, 2022). Bogado et al (2001) also supported the discrepancies between molecular and phenotypic classifications of methicillin resistance.…”

Staphylococcal mastitis in dairy cows

“…The most frequently seen resistance among staphylococci is resistance due to the production of β-lactamases, with more common production among subclinical non-aureus staphylococci isolates than clinical isolates ( 170 ). They exhibit resistance to multiple classes of antimicrobial drugs ( 32 , 171 , 172 ). The response to the treatment of S. aureus mastitis during lactation is poor ( 30 , 173–175 ), with a 25–75% quarter cure rate for treatment at dry-off and 3–63% for short-term treatment during lactation ( 174 , 175 ).…”

“…The most frequently seen resistance among staphylococci is resistance due to the production of β-lactamases, with more common production among subclinical non-aureus staphylococci isolates than clinical isolates ( 170 ). They exhibit resistance to multiple classes of antimicrobial drugs ( 32 , 171 , 172 ).…”

Non-aureus staphylococci and mammaliicocci as a cause of mastitis in domestic ruminants: current knowledge, advances, biomedical applications, and future perspectives – a systematic review

“…Due to improved sanitation of milk production practices and milk heat treatments, the threat of various diseases and the incidence of outbreaks related to milk and dairy products have been greatly reduced in developed countries. However, a variety of microorganisms still contribute to disease outbreaks (Ibrahim et al 2022 ; Hussein et al 2022 ). In cases of severe clinical mastitis, milk abnormalities are easily observed, and the milk must be discarded so that milk would not normally enter the food chain.…”

“…The production of beta-lactamases is the most common resistance mechanism in staphylococci, and its production is more common among subclinical NASM isolates than clinical isolates (De los Santos et al 2022 ). NASM species may exhibit resistance to the following antimicrobials: penicillin, cefoxitin, erythromycin, clindamycin, gentamicin, streptomycin, tetracycline, ciprofloxacin, chloramphenicol, fusidic acid, oxacillin, vancomycin, and trimethoprim-sulfamethoxazole (Gurler et al 2022 ; Ibrahim et al 2022 ; Raspanti et al 2016 ; Sawant et al 2009 ).…”