Detection of Biofilm Producer Methicillin Resistant Staphylococcus hominis Isolated From Different Clinical Sources

Abstract

Staphylococcus hominis is an opportunistic gram positive bacteria and is a member of coagulase-negative staphylococci (CoNS) . During the study, 213 clinical specimens were collected from patients admitted to different hospitals in Erbil city, Iraq. Only 18(8.45%) isolates of S. hominis were isolated including 7 isolates (17.07%) from blood, 4 isolates (8.70%) from urine, 3 isolates (7.14%) from ear, 2 isolates (6.67%) from wound, and one isolate from each nasal swab (4.55%) and oral cavity (3.13%), all S. hominis identified based on morphology, cultural, biochemical tests, and further confirmed by Vitek 2 compact system. To determine the most accurate assay for measuring methicillin resistance S. hominis, compared the detection of mecA by PCR with detection by National Committee for Clinical Laboratory Standards methods using oxacillin and Cefoxitin disk diffusion method. The results of oxacillin showed 13 (72.22%) isolates resistant to methicillin and 5 (27.77%) isolates were sensitive to it. While, the results of cefoxitin demonstrated that 16 (88.89%) isolates were resistant to methicillin and only 2 isolates (11.11%) were sensitive to it. However, the same results of the Cefoxitin disk diffusion method was obtained by PCR and by using mecA gene which 16 isolates (88.89%) were carried mecA gene with product size 499bp. The results of microtiter plate method revealed that 16 (88.89%) isolates of S. hominis were biofilm producer and only 2 isolates (11.11%) were non-biofilm producer. Moreover,of 16 biofilm producer isolates, 14 isolates (77.77%) were categorized as strong biofilm producers and 2 (11.11%) isolates were identified as moderate biofilm producers.