Species Distribution and Virulence Factors of Coagulase Negative Staphylococci Isolated From Clinical Samples From the University of Benin Teaching Hospital, Edo State, Nigeria.

Abstract

Coagulase negative staphylococci (CoNS) have become a major public health problem due to an increase in invasive procedures and antibiotic resistance. The prevalence and some virulence factors of CoNS species isolated from clinical samples obtained from a hospital in Benin-City, Nigeria was investigated. A total of 79 clinical samples were collected from clinical specimens over a six month period in a non consecutive manner from a teaching hospital in Nigeria. Samples were cultured on MacConkey agar, Cystine –Lysine-Electrolyte-Deficient agar (CLED) and blood agar (Oxoid Ltd Basingstoke UK). Identification of the various CoNS species was done using Microbact staph ID system (Oxoid product). Determination of hemolysin production was done in blood agar plates while slime detection was carried out using the modified congo red agar method. The most commonly isolated species were S. haemolyticus (28.3%), S. epidermidis (26.7%) and S. saprophyticus (18.33%). Others were S. simulans (10%), S. xylosus (10%), S. chromogenes (15%) and S. schleiferi (1.67%). Hemolysis on blood agar plates was observed in 34.2% of CoNS with S. haemolyticus (58.8%) predominating followed by S. epidermidis (25%). Slime production was positive in 75.95% of all CoNS species isolated. All isolates of S. simulans (100%) and S. xylosus (100%) were positive for slime production followed by S. epidermidis (93.7%) and S. haemolyticus (70.6%). Due to the increasing medical significance of CoNS, these organisms should not be ignored or classified as mere contaminants.

Keywords: Coagulase negative Staphylococcus, virulence factors, infections, slime, hemolysin.