Staphylococcal bacteraemia among human immunodeficiency virus positive patients at a screening center in Lagos, Nigeria

Bacteraemia due to Staphylococcus aureus in Human immunodeficiency virus (HIV) - positive patients is associated with increased mortality rate. The present study aimed at determining the species distribution and occurrence of staphylococcal bacteraemia in HIV - positive patients in Lagos, Nigeria. Staphylococcal blood stream infection in febrile HIV patients was investigated by culture technique. The antibiotic resistance pattern was investigated using the disk diffusion and methicillin resistance was confirmed by the salt agar methods. The genetic relatedness of S. aureus was determined using Pulsed Field Gel Electrophoresis (PFGE). Eighty-six patients comprising 47 (55%) female and 39 (45%) male, median aged 34 years took part in the study. Staphylococci were identified in 16 (18.6%) patients; 13 (15.1%) and 3 (3.5%) with single and dual Staphylococcus species respectively. The isolates consisted of S. aureus (7 patients), followed by S. haemolyticus (4 patients). Of the thirteen (13) antibiotics tested, isolates were resistant to ampicillin (AMP; 89.5%), tetracycline (TET; 68.4%), cloxacillin (CXC; 89.5%), oxacillin (OXA; 68.4%); chloramphenicol (CHL; 57.9%) and trimethoprim-sulphamethoxazole (SXT; 63.1%). The overall percentage of all the isolates resistant to gentamicin, erythromycin and amoxicillin-clavulanic acid was less than 50%. All the isolates were susceptible to ciprofloxacin and vancomycin and none was positive for methicillin resistance except a strain of S. haemolyticus. Significant genetic diversity was observed among the S. aureus isolates with a predominant pulsotype A. The two isolates with pulsotype A had identical resistotype (AMP, ERY, TET, CXC, SXT). Other PFGE patterns were represented by single isolates except pulsotype C which had a subtype. In these patients, the most frequent Staphylococcus species isolated was S. aureus and the results revealed that clonal dissemination of a virulent pulsotype of S. aureus among this population is plausible and should be a cause for concern.