Molecular detection of methicillin resistance gene (mec A gene) and pathogenic genes among Staphylococcus aureus isolates from clinical and drinking water samples of HIV and AIDS patients in Limpopo

Abstract

In the present study, Staphylococcus aureus strains isolated from de-identified clinical samples including urine, sputum, and stools obtained from Human Immunodeficiency virus (HIV) and Acquired immunodeficiency syndrome (AIDS) patients as well as their drinking water samples were analysed. Antibiotic resistance was tested by the disc diffusion while biofilm was tested using the microplate method. Methicillin resistance was tested from all the S. aureus isolates by the oxacillin agar plate and the mec A gene was detected by the polymerase chain reaction (PCR) method. A subset of 50 isolates randomly selected were analysed for the presence of 5 different S. aureus enterotoxins (SEA-SEE) using a multiplex PCR procedure, of the 140 S. aureus isolates from 478 samples, 18 (14%) were methicillin-resistant S. aureus (MRSA) and 3 out of the 18 showed resistance to vancomycin (17%) compared to methicillin sensitive S. aureus(MSSA) among which vancomycin resistance was 11%. Methicillin resistance was more common among the sputum isolates 4 (27%) compared to 7 (15.5%) and 7 (12%) from urine and stool isolates. None of the 17 water isolates was positive for MRSA. Pathogenic genes were detected in 13 (26%) isolates. Staphylococcus enterotoxin A (SEA) was the most commonly detected gene 12 (24%) and was more prevalent among organisms isolated from urine 8 (35%) (χ2 = 8.196; p = 0.042). The present study indicated thatStaphylococcus enterotoxin A is the most common pathogenic gene. Based on the results obtained, it can be hypothesised that pathogenic S. aureus (producing biofilm and staphylococcal enterotoxin A) are responsible for urinary tract infections among HIV patients in the Limpopo Province. Furthermore, water could be a transmission vector of staphylococcal UTIs among HIV and AIDS patients in this region. However, further studies are needed to confirm these hypotheses. Key words: HIV and AIDS, Staphylococcus aureus, biofilm, antibiotic susceptibility, epidemiology, Venda, South Africa, toxins, mec A.