Molecular profiling of virulence determinants and antimicrobial resistance in MRSA isolates from HIV-infected and non-HIV individuals.

BACKGROUND

Staphylococcus aureus is an important pathogen exhibiting antibiotic resistance and multiple virulence factors. This study analyses the antimicrobial resistance and virulence genes of Staphylococcus aureus isolates from HIV and non-HIV patients from southern India.

METHODS

S. aureus strains from HIV (n = 125) and non-HIV (n = 100) patients were isolated using conventional bacterial culture techniques. Antimicrobial resistance and virulence genes were analysed using polymerase chain reaction (PCR).

RESULTS

Methicillin resistance was detected in 88.8 % and 34 % of the S. aureus isolates from HIV and non-HIV patients, respectively, and all tested positive for the mecA gene. SCCmec type V was the most frequently detected SCCmec cassette in MRSA from both HIV (55.2%) and non-HIV patients (44.4 %). MRSA isolates from HIV patients were 98.2 % positive for the penicillin resistance gene blaZ, followed by the aminoglycoside resistance genes aacA-aphD (82 %), aac(6')/aph(2″) (75.7 %) and aph(3″)-IIIa (51.4 %), the tetracycline resistance genes tet(K) (42.3 %) and tet(M) (13.5 %) and the erythromycin resistance genes erm(C) (55 %). Among the non-HIV-infected MRSA strains, 73.5 % were positive for blaZ, followed by aac(6')/aph(2″) (50 %), aacA-aphD (47.1 %), aph(3")-IIIa (23.5 %), and erm(C) (29.4 %). The seb (7.2 %), sea (5.4 %), seb and sed (2.7 %), exfoliative toxin gene eta (3.6 %) and toxic shock syndrome toxin gene tst (8.1 %) were detected among MRSA from HIV patients, and the sea (5.9 %), sec (5.9 %), eta (5.9 %) and tst (8.8 %) were found among MRSA from non-HIV patients.

CONCLUSIONS

HIV patients are at a relatively greater risk of acquiring virulent and multidrug-resistant methicillin-resistant S. aureus infections than non-HIV patients.