title: Frequent occurrence of oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) strains in two African countries.
abstract: BACKGROUND
  Oxacillin-susceptible mecA-positive Staphylococcus aureus (OS-MRSA) isolates have been increasingly reported worldwide, but data regarding the African continent have not been available.
  
  
  METHODS
  Between 2010 and 2014, 1462 inpatients and healthcare workers were screened for MRSA nasal carriage in São Tomé and Príncipe (STP) and Angola, two Portuguese-speaking African countries (PALOP countries). We determined the presence of the mecA gene and the antimicrobial susceptibility profiles of the isolates. OS-MRSA clonal lineages were identified as well as the presence of virulence determinants, including Panton-Valentine leucocidin (PVL).
  
  
  RESULTS
  Out of 164 S. aureus hospital isolates tested, 29 (17.7%) were mecA positive, but susceptible to oxacillin, showing oxacillin MICs ≤3 mg/L. All OS-MRSA isolates were resistant to cefoxitin and most of them were also resistant to at least two antimicrobials other than β-lactams. The 29 OS-MRSA were distributed into two major clonal lineages: (i) PFGE type B-ST88-SCCmec IVa, associated with spa types t186/t325/t786/t1814/t1951, detected in Angola (n = 5) and STP (n = 10); and (ii) PFGE type C-t451/t648-ST8-SCCmec V, exclusively found in STP (n = 9). OS-MRSA showed at least two virulence determinants. PVL was detected in an isolate recovered in STP.
  
  
  CONCLUSIONS
  We describe a high prevalence of OS-MRSA among S. aureus strains recovered in two African countries. OS-MRSA in PALOP countries were mainly associated with ST88 and ST8, two prevalent MRSA clonal types in these countries. If direct testing for mecA is not available, cefoxitin susceptibility testing is highly recommended to avoid the misidentification of OS-MRSA.
authors: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier (ITQB), Universidade Nova de Lisboa (UNL), Oeiras, Portugal.
authors: Teresa
authors: T
authors: Conceição
authors: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier (ITQB), Universidade Nova de Lisboa (UNL), Oeiras, Portugal.
authors: Céline
authors: C
authors: Coelho
authors: Laboratory of Molecular Genetics, Instituto de Tecnologia Química e Biológica António Xavier (ITQB), Universidade Nova de Lisboa (UNL), Oeiras, Portugal Laboratory of Microbiology and Infectious Diseases, The Rockefeller University, New York, NY, USA.
authors: Hermínia
authors: H
authors: de Lencastre
authors: Escola Superior de Saúde da Cruz Vermelha Portuguesa (ESSCVP), Lisboa, Portugal msousa@esscvp.eu.
authors: Marta
authors: M
authors: Aires-de-Sousa
mesh_terms: D000810:Angola / Q000453:epidemiology; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D001266:Atlantic Islands / Q000453:epidemiology; D001426:Bacterial Proteins / Q000235:genetics*; D002353:Carrier State / Q000453:epidemiology / Q000382:microbiology; D005838:Genotype; D006282:Health Personnel; D006801:Humans; D007297:Inpatients; D055624:Methicillin-Resistant Staphylococcus aureus / Q000187:drug effects / Q000302:isolation & purification*; D008826:Microbial Sensitivity Tests; D058889:Molecular Typing; D010068:Oxacillin / Q000494:pharmacology*; D046915:Penicillin-Binding Proteins / Q000235:genetics*; D015995:Prevalence; D013203:Staphylococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D037521:Virulence Factors / Q000235:genetics; D018440:beta-Lactam Resistance
chemical_list: D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D046915:Penicillin-Binding Proteins; D037521:Virulence Factors; C487789:mecA protein, Staphylococcus aureus; D010068:Oxacillin