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Open Access Highly Accessed Research article

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

Adebayo Shittu12*, Omotayo Oyedara13, Fadekemi Abegunrin1, Kenneth Okon4, Adeola Raji5, Samuel Taiwo6, Folasade Ogunsola7, Kenneth Onyedibe8 and Gay Elisha2

Author Affiliations

1 Department of Microbiology, Obafemi Awolowo University, Ile-Ife, Nigeria

2 Division of Medical Microbiology, University of Cape Town, Cape Town, Republic of South Africa

3 Department of Biological Sciences, College of Science, Engineering and Technology, Osun State University, Osogbo, Nigeria

4 Department of Medical Microbiology, University of Maiduguri Teaching Hospital, Maiduguri, Nigeria

5 Department of Medical Microbiology and Parasitology, Lagos State University Teaching Hospital, Lagos, Nigeria

6 Department of Medical Microbiology and Parasitology, Ladoke Akintola University of Technology Teaching Hospital, Ogbomosho, Nigeria

7 Department of Medical Microbiology and Parasitology, College of Medicine, University of Lagos, Lagos, Nigeria

8 Department of Medical Microbiology and Parasitology, Jos University Teaching Hospital, Jos, Nigeria

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BMC Infectious Diseases 2012, 12:286  doi:10.1186/1471-2334-12-286

Published: 2 November 2012

Abstract

Background

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.

Methods

Identification and antibiotic susceptibility testing was performed using the VITEK 2 system, detection of resistance genes by PCR, and molecular characterization was determined by SCCmec typing, spa and multilocus sequence typing (MLST).

Results

All the isolates were susceptible to mupirocin, tigecycline, vancomycin and linezolid, but 72.5% of CNS and 82.3% of Staphylococcus aureus were resistant to cotrimoxazole, while multiresistance was observed in 37 of the 40 CNS isolates. Untypeable SCCmec types (ccrC/Class A mec and ccr-negative/Class C2 mec gene complex) in two methicillin-resistant S. aureus (MRSA) were identified. Additionally, ccr-negative/Class A mec and ccr type 4/Class C2 mec gene complex was detected in one isolate each of S. sciuri and S. haemolyticus, respectively. The S. aureus isolates were classified into 21 spa types including two new types (t8987, t9008) among the methicillin-susceptible S. aureus (MSSA) isolates. Two (CC8-SCCmecnon-typeable and CC88-SCCmec IV) and four (CC8-SCCmec III/IV/V; CC30-SCCmec II/III; CC88-SCCmec IV; and ST152-SCCmecnon-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.

Conclusions

The identification of multiresistant mecA positive S. haemolyticus and S. sciuri 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 SCCmec classification methods for non-typeable methicillin-resistant staphylococci, and to curtail the spread and establishment of the S. aureus ST152 clone in Nigeria. The study presents the first report of a PVL-positive ST152-SCCmecnontypeable MRSA and SCCmec typing of methicillin-resistant CNS in Nigeria.

Keywords:
Coagulase negative staphylococci; Staphylococcus aureus; Multiresistance; mecA gene; Staphylococcus haemolyticus; Staphylococcus sciuri; Panton Valentine Leukocidin; SCCmec typing; ST152; Nigeria