Prevalence of Staphylococcus aureus and Staphylococcus sciuri Isolated from Apparently Healthy and Hospitalized Patients in Ekiti State, Nigeria

Abstract

The emergence of microbial resistance to antibiotics on daily basis has become a major global challenge. The increasing prevalence of methicillin resistant Staphylococcus aureus (MRSA) infections among hospitalized and non-hospitalized patients due to emergence of unique community-associated strains has become a great problem in Nigeria in particular and the entire world in general. In this study, a total of four hundred (400) clinical specimens were collected from hospitalized patients at Ekiti State University Teaching Hospital (EKSUTH), Ado-Ekiti and Federal Teaching Hospital (FETHI), Ido-Ekiti and from apparently healthy individuals from both communities. Standard bacteriological procedures were employed to isolate and identify these organisms. Antibiotic susceptibility test was carried out using the modified Kirby Bauer disc diffusion method. Polymerase chain reaction (PCR) assay was used to identify S. aureus nuc gene, as well as mecA and aac resistance genes. Seventy seven (19.3%) S. aureus isolates were phenotypically identified; 43 (21.5%) hospital-associated (23 from EKSUTH and 20 from FETHI) and 34 (17.0%) community-associated (27 from Ado-Ekiti and 7 from Ido-Ekiti communities). No S. sciuri was phenotypically isolated in both locations.  Fifty five (71.4 %) of the 77 S. aureus isolates were nuc gene positive, while 11 (20%) of the 55 isolates were mecA gene positive, implying that they were MRSA. Of the 11 isolates, 6 (19.4%) were hospital-associated MRSA while 5 (20.8 %) were community-associated MRSA. Phenotypic resistance of S. aureus to cefoxitin in the two locations ranged between 77.8 – 100%, but 80% of cefoxitin-resistant nuc gene positive S. aureus lacked mecA gene. S. aureus isolates exhibited high phenotypic resistance to tetracycline, erythromycin and fusidic acid but susceptible to clindamycin and gentamycin. The prevalence of clinical MRSA infection of 20% in this study is relatively high. However, there was 0% prevalence of S. sciuri colonization. Cefoxitin disc test demonstrated low specificity as a phenotypic marker of methicillin resistance.There is need to institute control measures for MRSA infections and colonization in this environment.