Characterization of methicillin-susceptible and -resistant staphylococci in the clinical setting: a multicentre study in Nigeria

• Main Authors: Shittu Adebayo, Oyedara Omotayo, Abegunrin Fadekemi, Okon Kenneth, Raji Adeola, Taiwo Samuel, Ogunsola Folasade, Onyedibe Kenneth, Elisha Gay
• Format: Article
• Language: English
• Published: BMC 2012-11-01
• Series: BMC Infectious Diseases
• Subjects: Coagulase negative staphylococci; <it>Staphylococcus aureus</it>; Multiresistance; <it>mecA</it> gene; <it>Staphylococcus haemolyticus</it>; <it>Staphylococcus sciuri</it>; Panton Valentine Leukocidin; SCC<it>mec</it> typing; ST152; Nigeria
• Online Access: http://www.biomedcentral.com/1471-2334/12/286

<p>Abstract</p> <p>Background</p> <p>The staphylococci are implicated in a variety of human infections; however, many clinical microbiology laboratories in Nigeria do not identify staphylococci (in particular coagulase negative staphylococci - CNS) to the species level. Moreover, data from multi-centre assessment on antibiotic resistance and epidemiology of the staphylococci are not available in Nigeria. This study investigated 91 non-duplicate staphylococcal isolates obtained from the microbiology laboratories of eight hospitals in Nigeria during the period January to April 2010.</p> <p>Methods</p> <p>Identification and antibiotic susceptibility testing was performed using the VITEK 2 system, detection of resistance genes by PCR, and molecular characterization was determined by SCC<it>mec</it> typing, <it>spa</it> and multilocus sequence typing (MLST).</p> <p>Results</p> <p>All the isolates were susceptible to mupirocin, tigecycline, vancomycin and linezolid, but 72.5% of CNS and 82.3% of <it>Staphylococcus aureus</it> were resistant to cotrimoxazole, while multiresistance was observed in 37 of the 40 CNS isolates. Untypeable SCC<it>mec</it> types (<it>ccrC</it>/Class A <it>mec</it> and <it>ccr</it>-negative/Class C2 <it>mec</it> gene complex) in two methicillin-resistant <it>S. aureus</it> (MRSA) were identified. Additionally, <it>ccr</it>-negative/Class A <it>mec</it> and <it>ccr</it> type 4/Class C2 <it>mec</it> gene complex was detected in one isolate each of <it>S. sciuri</it> and <it>S. haemolyticus</it>, respectively. The <it>S. aureus</it> isolates were classified into 21 <it>spa</it> types including two new types (t8987, t9008) among the methicillin-susceptible <it>S. aureus</it> (MSSA) isolates. Two (CC8-SCC<it>mec</it>non-typeable and CC88-SCC<it>mec</it> IV) and four (CC8-SCC<it>mec</it> III/IV/V; CC30-SCC<it>mec</it> II/III; CC88-SCC<it>mec</it> IV; and ST152-SCC<it>mec</it>non-typeable) MRSA clones were identified in Maiduguri (North-East Nigeria) and South-West Nigeria, respectively. The proportion of Panton-Valentine leukocidin (PVL)-positive MSSA was high (44.4%) and 56.3% of these strains were associated with sequence type (ST) 152.</p> <p>Conclusions</p> <p>The identification of multiresistant <it>mecA</it> positive <it>S. haemolyticus</it> and <it>S. sciuri</it> from clinical samples indicates that characterization of CNS is important in providing information on their diversity and importance in Nigeria. There is the need to develop new SCC<it>mec</it> classification methods for non-typeable methicillin-resistant staphylococci, and to curtail the spread and establishment of the <it>S. aureus</it> ST152 clone in Nigeria. The study presents the first report of a PVL-positive ST152-SCC<it>mec</it>nontypeable MRSA and SCC<it>mec</it> typing of methicillin-resistant CNS in Nigeria.</p>