Antibiotic resistance patterns of coagulase negative Staphylococcus (CoNS) strains isolated from blood stream infections in Babylon province, Iraq

Abstract

Background: Identification of coagulase-negative staphylococci (CoNS) as nosocomial pathogens or contaminants is significant for microbiologists and clinicians. Aims: This study aimed to determine the frequency of isolation and antimicrobial resistance patterns of CoNS isolates from nosocomial bloodstream infections (BSIs). Methods: This studyincluded 15 coagulase-negative Staphylococcus (CoNS) isolates out of a total of 230 clinical bloodstream samples. Patients were admitted to five main hospitals in Hilla city, Iraq, during the period from July 2019 to September 2020. Results: Fifteen (57.6%) CoNS isolates were recovered from patients with bloodstream infections. The phenotypic identification revealed that isolates belonged to five different species; Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus warneri, Staphylococcus hominis, and Staphylococcus capitis. The results of susceptibility of CoNS isolates to oxacillin showed that 13(86.7%) isolates were oxacillin resistant (MR-CoNS).The antibiotic susceptibility testing against 15 antibiotics showed that resistance rates were variable towards these antibiotics. Results also revealed that 13(86.7%) of isolates were β-lactam resistant and 11(73.3%) of them were biofilm producers. Results of molecular detection of mecA gene, vanA / vanB gene, found that mecA gene was detected in all isolates (100%). However, none of CoNS isolates were found to harbor vanA / vanB genes. Conclusion: Coagulase-negative staphylococci (CoNS) are associated with bloodstream infections andcharacterized by resistance to commonly used antibiotics, and sensitivity to Vancomycin, Teicoplanin, and linezolid, in addition to their ability of biofilm production.