Cooccurrence of Predominant Panton-Valentine Leukocidin-Positive Sequence Type (ST) 152 and Multidrug-Resistant ST 241 Staphylococcus aureus Clones in Nigerian Hospitals

Abstract

Ninety-six clinical isolates ofStaphylococcus aureus is a major cause of both hospital-and community-acquired infections. In particular, methicillin (meticillin)-resistant S. aureus (MRSA) strains have been detected worldwide (15), and the prevalence of MRSA varies among countries and health institutions (2,4,27). The emergence of MRSA strains resistant to glycopeptides, as well as the increasing prevalence in the community (7), highlights the need for worldwide epidemiological studies of this pathogen. However, data about the epidemiology and prevalence of staphylococcal infections in Africa are scarce compared to information about such infections in the rest of the world. Studies have indicated low prevalences of MRSA in Nigeria, Somalia, and Tanzania (1), but high prevalences in South Africa, Zimbabwe, Kenya, Ethiopia, Egypt, Senegal, and the Ivory Coast have been reported (2,9,18). In addition, a recent study of the genetic diversity of S. aureus strains in a carriage population from Mali showed a high frequency of a PantonValentine leukocidin (PVL)-positive clone (25). The mechanisms for the emergence and spread of S. aureus clones in Africa are largely unknown; hence, the characterization of isolates may provide baseline information needed in establishing effective infection control measures in Nigeria.In this study, a total of 96 S. aureus isolates obtained between January and December 2007 from clinical specimens in six tertiary-care hospitals located in northeastern Nigeria were characterized. The isolates were identified based on standard bacteriological procedures (i.e., Gram staining and catalase, tube coagulase, and DNase testing), and susceptibilities to 12 antibiotics (Table 1) were determined by the disk diffusion method according to the CLSI guidelines. All the isolates were susceptible to vancomycin, fusidic acid, and mupirocin, and 12 (12.5%) were resistant to methicillin (i.e., oxacillin and cefoxitin resistant) ( Table 1). The MRSA isolates were multidrug resistant (i.e., resistant to beta-lactams, along with at least three other classes of antibiotics), a finding similar to previously reported findings in other African countries like Morocco, Kenya, Cameroon, and South Africa (17). MRSA resistance to non-beta-lactams may further increase the medical expenses and the complexity of patient management, as well as morbidity and mortality rates since alternative antibiotics may not be affordable in many African countries.The genetic diversity of the S. aureus population was assessed by the highly discriminatory double-locus sequence typing (DLST) method as described previously (20). This method is based on the analysis of partial sequences (about 500 bp) of the variable clfB and spa genes. A total of 41 clfB and 46 spa alleles were observed among the 96 S. aureus isolates evaluated by DLST, and these alleles represented 53 different DLST types. The eBURST software was used to cluster DLST types with identical sequences of at least one allele. Cluster analysis showed a low level of diversity amon...

Use of Triplex PCR for Rapid Detection of PVL and Differentiation of MRSA from Methicillin Resistant Coagulase Negative Staphylococci

“…PVL is a necrotizing cytotoxin which is specific for the human and rabbit polymorphonuclear cells [20], which may be responsible for the Staphylococcal invasiveness and virulence. In developing countries like India [19,21], Africa [22] and other Asian countries [23], the prevalence rate of the pvl positive CA-MRSA is very high as compared to those at other geographic locations [17,24]. Even in this study, about 12% of the MSSA and 40% of the MRSA were found to be positive for PVL, which was slightly higher than that which was reported from other geographical regions and lower than the reports from Africa and India.…”

<i>Staphylococcus aureus</i> Prevalence and Antibiotic Susceptibility Profile in Anyigba, North-Central Nigeria

“…MRSA has become a major public health problem worldwide and recent reports have indicated that the prevalence of hospital -associated MRSA in health care institutions in Nigeria may vary from 1.5% to 20% (Okon et al, 2009). In this study, screening for MRSA revealed a prevalence rate of 13% which agrees with a study conducted in north-eastern Nigeria by Okon et al (2013) who reported a prevalence of 12.5%.…”

“…Also, a number of investigations have reported that Staphylococcus aureus is among the most frequently encountered bacterial species in microbiology laboratories in Nigeria (Okon et al, 2009;Odetoyin et al, 2008;Ubani, 2009). For effective treatment of Staphylococcus aureus infections, adequate information and data on susceptibility patterns and characterization of the organism are of great importance (Esan et al, 2009).…”

Distribution of genes encoding aminoglycoside modifying enzymes amongst methicillin resistant and methicillin sensitive Staphylococcus aureus isolates from Nigerian hospitals

“…This strain of S. aureus has been reported virtually in all the countries of the world with varying frequencies (Dufour et al, 2002;Kesah et al, 2003;Crum et al, 2006). Nigeria has not been exempted from the global epidemic strain (Ghebremedhin et al, 2009;Okon et al, 2009;Alli et al, 2012). The gene encoding the MRSA phenotype has been linked to mecA gene on the chromosome that encodes a modified penicillin binding protein 2 (PBP2).…”