Spread of Staphylococcus aureus resistant genes to antibiotics: Clones and genetic elements (toxin genes)

Abstract

Antibiotic overuse has led to the emergence of resistant strains of bacteria, such as Methicillin-resistant Staphylococcus aureus (MRSA), which has become a global public health concern. The aim of this study was to investigate the genetic and microbiological characteristics of MRSA in hospitals in Crete, located in the southeastern Balkan region. S. Aureus samples were collected from hospitalized patients and tested for antibiotic susceptibility using the Kirby-Bauer disk diffusion method. The presence of mecA, enterotoxin genes (sem gene or seg genes), agr genes, and PVL genes was detected using PCR. Of the 141 S. Aureus strains tested, 102 (72.34%) were found to have the genes of interest, with 69 MRSA (48.9%) mecA+ strains and 33 methicillin-susceptible S. Aureus (MSSA) mecA negative strains. The most prevalent gene detected was the agr gene (48.93%), followed by the enterotoxin gene (44.68%). Four agr groups (I – IV) were detected in 69 MRSA isolates (48.9%). This study highlights the prevalence of MRSA in hospitals in Crete and emphasizes the importance of appropriate antibiotic use and infection control measures to prevent the spread of antibiotic-resistant bacteria. Although a correlation between the presence of the detected genes and certain resistance phenotypes was not observed, the findings indicate the necessity to trace these genes using PCR and involve them in clinical diseases. The circulation of sensitive strains to antibiotics and resistant strains to some antibiotics with different resistance phenotypes was also noted in the hospital. Overall, this study provides important insights into the genetic and microbiological characteristics of MRSA in the southeastern Balkan region, and the results can inform future efforts to control the spread of antibiotic-resistant bacteria.