Incidence of Methicillin Resistant mecA and Investigation of Biofilm Formation in some Clinical Isolates of Staphylococcus aureus in Baghdad

Abstract

The most prevalent pathogenic bacteria in hospitals and communities is Methicillin resistant Staphylococcus aureus (MRSA). Its capacity to form biofilms is thought to be the primary factor in its pathogenicity since it confers resistance to both human immune response and medications, so the purpose of this investigation was to assess the development of biofilms and their correlation with antibiotic resistance in MRSA clinical isolates. From 150 swabs taken from various clinical sources of patients at several hospitals in Baghdad, Iraq, 36 S. aureus were isolated. The study was conducted from November 2023 to March 2024, a span of five months. The diagnosis of S. aureus isolates was made using molecular methods, biochemical testing, and phenotypic characteristics. The molecular technique relied on PCR for gene specific detection, 16S rRNA for staphylococcus genus diagnosis, and mecA for methicillin-resistant S. aureus diagnosis. Antibiotic susceptibility to eleven different antibiotics showed that S. aureus has an elevated  resistance to Cefoxitin (alternative to Methicillin) (55.55%) and Vancomycin (55.55%) While the other antibiotics have varying rates of resistance: Azithromycin (38.88%), Doxycycline (30.55%), Levofloxacin and Clindamycin (16.66%), Gentamicin, Rifampin and Trimethoprime-sulfamethoxazole (11.11%), Chloramphenicol (8.33%). The results of using the microtiter plate method (MTPs) for biofilm identification revealed that all S.aureus isolates produced biofilm in different degrees, strong (30.55%), moderate (52.77%) and weak (16.66%). S. aureus had a 97.22% MRSA incidence. In summary, a high mecA percentage is associated with a high rate of biofilm formation and antibiotic resistance, so methicillin-resistant S. aureus is a developing issue, even in our neighborhood, that needs more care and attention.