Molecular characterization of methicillin-resistant Staphylococcus aureus isolates from rural community settings in Trinidad and Tobago

Abstract

Aims: To determine the virulence and antimicrobial resistant genes in methicillin resistant Staphylococcus aureus isolates recovered from patients attending two rural health centers in Trinidad and Tobago.

Settings and Design: Cross‑sectional observational analysis of patients from two local health centers located in communities in northern region of the country.

Materials and Methods: Nasal and wound swabs from 300 patients were analyzed using standard and molecular techniques. Multiplex polymerase chain reaction was used to detect 16S rRNA, mecA, Staphylococcal chromosomal cassette SCC mec types, pvl, alpha hemolysin (hla), and Toxic Shock Syndrome Toxin 1 (tst1) genes. S. aureus ATCC 33591 and Staphylococcus epidermidis ATCC 12228 were used for quality control, respectively.

Results: Over a quarter (26.7%, 80/300) of the surveyed patient’s samples grew bacterial isolates of which 45% (36/80) were S. aureus and 44.4% (16/36) were mecA‑positive. Majority (62.5%, 10/16) possessed the pvl gene, whereas 25% (4/16) possessed the alpha hemolysin (hla) gene. None of the methicillin‑resistant Staphylococcus aureus (MRSA) isolates possessed the tst1 gene. Also, 18.8% (3/16) isolates possessed both virulence genes, pvl and hla. Although the SCCmec types IV and V were detected, but none of the SCCmec I, II, and III were harbored by the isolates.

Conclusions: SCCmec type IV and the pvl genes were common among the MRSA isolates from the community. The hla gene was found infrequently, but none of the isolates possessed the tst1 gene. Knowledge of this is important for robust surveillance of such cases from the community in the country.

Keywords: Community‑associated methicillin‑resistant Staphylococcus aureus, hya gene, pvl gene, SCCmec types, Trinidad and Tobago, tst1