Emergence of S. Lugdunensis in Burn Wound Infection of Hospitalized Patients

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Introduction: Although Coagulase Negative Staphylococci (CoNS) were previously considered to be harmless bacteria, some species have recently been shown to be potential pathogens in humans. One of these species, which has emerged in nosocomial infections, is Staphylococcus lugdunensis. Given the importance of recognizing new infections in hospital settings and their prevention, the present study aimed to investigate the presence of S. lugdunensis in patients with burn injuries. Materials and Methods: In this study, 124 CoNS isolates were evaluated in the patients admitted in a burn injury center in the southwest of Iran during January 2016-May 2017. The detected S. lugdunensis isolates were assessed in terms of drug susceptibility pattern, β-lactamase production, mecA-mediated oxacillin resistance, and inducible clindamycin resistance. The applied methods included disk diffusion, penicillin minimal inhibitory concentration, cefoxitin broth microdilution, and erythromycin/clindamycin disk diffusion, respectively. Results:Among the CoNS samples, 25 cases (20.2%) were S. lugdunensis. In the confirmed isolates, mecA-mediated oxacillin resistance was detected in 21 cases (84%), and 18 isolates (72.0%) produced β-lactamase. In addition, 23 isolates (88.5%) showed inducible clindamycin resistance. In the antibiogram pattern, more than 70% of the methicillin-resistant isolates were also resistant to chloramphenicol, trimethoprim/sulfamethoxazole, gentamicin, azithromycin, and ceftazidime. Conclusion: According to the results, S. lugdunensis was the cause of a new infection emerging in the studied burn injury center. Considering the resistance of the isolates against the most routine antibiotics, vancomycin is suggested as an alternative. Due to the prevalence of S. lugdunensis in different hospital wards, it is strongly recommended that CoNS isolates be evaluated for the detection of this bacterium.