Antibiotic sensitivity patterns in Staphylococcus spp. isolated from goat milk in association with molecular detection of antibiotic resistance genes

Microbes become unresponsive to the drugs used to treat infections due to their ability to acquire antimicrobial resistance.

The present research aimed to study the patterns of phenotypic and genotypic antimicrobial resistance in Staphylococcus spp. isolated from goat milk.

A total of 200 milk samples were collected to isolate Staphylococcus spp. from mastitic and healthy goats from Punjab state, India. The isolates were then identified biochemically and molecularly (polymerase chain reaction (PCR)). An antibiotic sensitivity test was conducted using 15 different antibiotics. Molecular detection of antibiotic resistance genes was done using PCR. Chi-square test was done to study the association between genotypic and phenotypic resistance patterns among the isolates.

A total of 47 Staphylococcus spp. were isolated of which 33 and 14 isolates were respectively coagulase positive and negative. The isolates phenotypically showed the highest resistance to Penicillin G (P) (91.4%). Methicillin resistant Staphylococcus aureus (MRSA) was found 56.25%. Amongst the antibiotic resistance genes, tetK (87.23%) was the most prevalent isolated gene followed by blaZ (85.10%), mecA (48.93%), and tetM (14.89%). Statistical analysis revealed that the genotypic and phenotypic resistance patterns were significantly associated with penicillin and methicillin (MET) resistances.

The high prevalence of antibiotic-resistant Staphylococcus spp., especially MRSA, in goat milk is of concern and needs to be addressed in this area.