Molecular Variation of Methicillin-resistant Staphylococcus haemolyticus Isolated from Patients in Ramadi City, Iraq.

Background: The increasing prevalence of Staphylococcus haemolyticus infections in community and hospital settings presents a significant health challenge due to growing antibiotic resistance and biofilm formation.

Objective: This study aims to:(1) perform a molecular analysis of prevalent native strains in Anbar, Iraq, (2) differentiate between various pathogenic strains using multilocus sequence typing (MLST) to enhance epidemiological and surveillance efforts. The objective is to trace the origins of these strains and distinguish between invasive and indigenous strains. While S. haemolyticus is generally part of the normal human microbiota, it can lead to serious infections in individuals with prior injuries or surgical procedures. It is particularly skilled at developing antibiotic resistance, making it a leading cause of hospital-acquired infections, largely through the staphylococcal cassette chromosome mec (SCCmec). Methicillin-resistant S. haemolyticus (MRSH) has developed resistance to oxacillin/cefoxitin through SCCmec acquisition, and hospital-associated MRSH strains are increasingly resistant to multiple antibiotics.

Methodology: The preparation of blood agar medium followed the manufacturer's guidelines. After autoclaving at 121ºC for 15 minutes, the medium was cooled to 50ºC. The mixture was then thoroughly mixed and poured into sterile Petri dishes. This medium is used for isolating and cultivating bacteria, as well as for detecting hemolytic activity and identifying the type of hemolysis. Genomic extraction and molecular screening of multidrug- resistant (MDR) isolates were performed, followed by MLST analysis. Data were processed using the University of Nebraska Medical Center's pubMLST website.

Results: To explore the genetic relationships among S. haemolyticus strains, their genomic DNA was analyzed using MLST typing based on the protocol from the MLST Institute database. All S. haemolyticus isolates in the study underwent MLST gene screening through PCR to verify the presence of housekeeping genes (arc, SH1200, hemH, leuB, SH1341, cfxE, and ribose ABC). PCR electrophoresis results demonstrated successful amplification of all target genes, confirming their appropriateness for MLST analysis. Three isolates were recognized as novel global strains, designated ST153, ST154, and ST155. In addition, five other strains were previously registered as ST3, ST9, ST29, ST123, and ST124.

Conclusion: The findings diverge from the established global understanding of type distribution in Asia. To combat the spread of highly resistant strains, it is crucial to monitor virulence factors and antibiotic resistance closely.