Multidrug Resistance and mupA-Mediated Mupirocin Resistance in Clinical Coagulase-Negative Staphylococci.

Coagulase-negative staphylococci (CoNSs) are major opportunistic pathogens in healthcare settings, particularly affecting immunocompromised patients and those with indwelling medical devices. Their growing antimicrobial resistance and ability to form biofilms present significant therapeutic challenges. This study analyzed 148 clinical CoNS isolates to determine species distribution, antimicrobial resistance, resistance genes, and biofilm production. Staphylococcus epidermidis was the most prevalent species (49.3%), followed by Staphylococcus hominis (27.0%) and Staphylococcus capitis (6.8%). Penicillin (83.8%), erythromycin (72.3%), and cefoxitin (66.2%) showed the highest resistance rates. Notably, 60.8% of isolates were resistant to fusidic acid and 45.3% to clindamycin, with inducible resistance in 12.1%. Among aminoglycosides, tobramycin resistance (45.3%) was most frequent. Resistance to ciprofloxacin and trimethoprim-sulfamethoxazole reached 45.9%, while mupirocin resistance was 17.6%. Among isolates resistant to penicillin and/or cefoxitin (n = 128), the mecA gene was detected in 69.5%; the mecC gene was absent. Only 38.5%% of mupirocin-resistant isolates carried the mupA gene. Trimethoprim resistance was mainly associated with dfrA (60.3%) and dfrG (14.7%). Biofilm super-producers accounted for 64.9% of isolates and non-producers for 7.4%, with no significant link between biofilm formation and antibiotic resistance. These findings reinforce the clinical relevance of multidrug-resistant, mupirocin-resistant, and biofilm-forming CoNSs, underscoring the need for improved surveillance and infection control.