Biofilm production and antibiotic susceptibility profiles of Staphylococcus aureus isolated from HIV and AIDS patients in the Limpopo Province, South Africa

Abstract

Staphylococcus aureus is a common pathogen associated with nosocomial as well as community acquired infections. Despite multiple reports on the severity and recurrent nature of S. aureus infection, the pathogenesis as well as antibiotic susceptibility profiles of S. aureus infecting HIV and AIDS patients has not been well studied in Limpopo Province, South Africa. Hence, the study was aimed at determining the biofilm producing capability and antibiotic resistance profiles of the S. aureus isolated from drinking water and clinical samples from HIV patients in the Limpopo Province. S. aureus strains isolated from clinical samples including urine, sputum, and stools obtained from HIV and AIDS patients as well as their drinking water samples were analysed for biofilm production using the microtitration plate method, haemolytic activities, antibiotic susceptibility, methicillin resistance and β-lactamase production. Methicillin resistance was tested from all the S. aureus isolates by the oxacillin agar plate. Overall, 140 S. aureus were isolated. Sixty (60) were from stools, 48 from urine, 15 from sputum and 17 from water. Of all the isolates, 67 (48%) produced biofilm of which 14 (10%) were strong biofilm producers and 53 (38%) moderate biofilm producers. Biofilm production was the highest among the urine isolates (62.5%) (χ2 = 6.276; p = 0.01) and the water isolates (70.6%) (χ2 = 4.006; p = 0.040). However, biofilm was not associated with sputum samples (p = 0.571) nor stool samples (p = 0.763). Isolates were highly resistant to most antibiotics tested and 125 (90%) isolates were resistant to more than 3 antibiotics. Higher resistance was observed against ampicillin (92%) while the most active antibiotic was ciprofloxacin with 89% susceptibility. Eighteen (14%) of the isolates were identified as MRSA and showed high resistance against vancomycin (28%) compared to MSSA among which vancomycin resistance was 14%. This is the first study on staphylococcal isolates from HIV patients in the Limpopo Province. The level of resistance to vancomycin was high and further attention is needed from the health system for more stringent measures of infection control. Biofilm production appeared to be a factor fuelling the increased in antibiotic resistance as well as pathogenicity in these strains. 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: Antibiotic susceptibility, biofilm, diarrhea, urinary tract infections, pulmonary infections, epidemiology, HIV and AIDS, Staphylococcus aureus, venda, South Africa.