Abstract
Antimicrobial and multidrug resistance is detected in nonaureus staphylococci, including Staphylococcus chromogenes, which commonly causes intramammary infections. Recent clinical studies point to the presence of methicillin-resistant S. chromogenes. Therefore, this study aims to determine the prevalence of this species in samples of sheep‘s milk and cheeses made from them. Isolates were identified by polymerase chain reaction and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI–TOF). A total of 208 staphylococcal isolates were identified. Of these, 18% were identified as S. chromogenes. The antimicrobial resistance of the identified isolates was determined using the agar dilution method against penicillin, ceftaroline, teicoplanin, gentamicin, erythromycin, tetracycline, and ofloxacin. The highest resistance was found to penicillin (95%), tetracycline (86%), and oxacillin (81%). The highest sensitivity was confirmed for gentamicin (55%). The study also confirmed the presence of methicillin resistant staphylococcal isolates (30%) based on the phenotypic manifestation of antimicrobial resistance and detection of the presence of the mecA gene. The study shows that the tested isolates (62%) were multidrug resistant. Resistance to two antibiotics was most often found (39%).
Highlights
Worldwide, sheep‘s milk consumption accounts for 1.3% of world milk production
Based on species identification of the iso3 loaft1e4d strains, a higher prevalence of S. chromogenes was detected in the raw sheep’s milk samples (20%; 23 isolates) compared to the samples made from sheep cheese (15%; 14 isolates)
Our study confirmed the presence of resistant, multiresistant strains and methicillinresistant strains of S. chromogenes in sheep’s milk and cheeses made from unpasteurized sheep’s milk
Summary
Sheep’s milk consumption is 10.6 million t/year, and the sheep population is 1.2 billion [1,2]. Bacteria of the genus Staphylococcus, which are the main cause of mastitis in dairy sheep, are often detected in sheep’s milk. They are responsible for more from 65% of mastitis cases. Staphylococcus chromogenes is one of the primary etiological agents of subclinical mastitis [5,7]. This type of staphylococcus has shown resistance to antibiotics in the dairy industry [6]
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