EVALUATION OF PHENOTYPIC AND GENOTYPIC METHODS TO DETECT METHICILLIN RESISTANCE IN STAPHYLOCOCCUS AUREUS (MRSA)

Dr. Sk. Shehab Hasan*, Prof. Dr. KM Shahidul Islam, Dr. Rafia Afreen Jalil and Dr. Adeeba Khanduker

ABSTRACT

Background: SSIs are the second most common nosocomial (hospital-acquired) infection after urinary tract infection even with modern facilities, standard protocols of preoperative preparation and antibiotic prophylaxis. Increasing antibiotic resistance of pathogens associated with SSI also becomes a major therapeutic challenge for the physicians. Methods: A cross sectional hospital based observational study was conducted in the department of Microbiology, BIRDEM General Hospital from period of September, 2018 to August, 2019. A total of 187 study participants clinically suspected as a case of SSI were investigated during the study period from two tertiary care hospitals of Dhaka city. Out of 187, 84 samples were collected from patients of laparoscopic surgery and 103 samples from open surgery. Among 103 samples from open surgery 50 were collected from general surgery ward and 53 from obstetrics & gynecology ward. The isolated organism from samples were identified on the basis of colony morphology on MacConkey agar and Blood agar media, hemolytic criteria, pigment production, gram staining character, coagulase test, catalase test. Catalase negative Gram positive organisms were further identified by bile esculin and NaCl tests. Phenotypically confirmed MRSA strains were further tested for mecA and PVL gene by PCR. Results: Among different surgical specialties, 82.1% culture positive cases were found from laparoscopic surgery, 82% & 73.5% from general surgery and obstetrical-gynecological surgery respectively. In BIRDEM General Hospital 81.7% (103/126) isolates were gram negative and 18.3% (23/126) were gram positive bacteria. In DMCH 85.6% (113/132) were gram negative and 14.3% (19/132) were gram positive bacteria. Staphylococcus aureas was the predominant gram positive bacteria among the total isolates. Among the MRSA isolates, 72.4% were positive for mecA and 24.1% were positive for PVL gene. Conclusion: Among the isolated MRSA strain, 72.4% were positive for the mecA gene and 24.1% were positive for the PVL gene. The information obtained from this study will be helpful in understanding SSI in terms of aetiological agents, their antimicrobial resistance pattern, distribution of MRSA producers, in treatment and prevention accordingly.

Keywords: Surgical Site Infection, Staphylococcus, Staphylococcus Aureus.