Determination of toxigenic capacity by RT-PCR in coagulase-negative staphylococci isolated from newborns in Brazil

  • Maria de Lourdes Cunha, Department of Microbiology and Immunology, Botucatu Institute of Biosciences, Botucatu, São Paulo State University/UNESP, SP., Brazil
  • Regina Calsolari, Department of Microbiology and Immunology, Botucatu Institute of Biosciences, Botucatu, São Paulo State University/UNESP, SP., Brazil
  • João Araújo Júnior, Brazil

    • Objectives: Identification and the determination of toxigenic capacity in CNS isolated of newborns hospitalized at the Neonatal Unit of the Hospital of the Botucatu Medical School, Unesp, Brazil. Methods: In the present study, 90 CNS strains isolated from different clinical materials of newborns were investigated by PCR for the presence of genes encoding staphylococcal toxins A (sea), B (seb), C (sec-1) and D (sed) and TSST-1 (tst). Strains positive for the presence of one or more genes were tested by RT-PCR for the expression of mRNA encoding the respective toxins. Results: S. epidermidis was the most frequently isolated organism, corresponding to 71.1% of all CNS strains investigated, followed by S. warneri (6.7%), S. haemolyticus (5.6%), S. hominis (5.6%), S. lugdunensis (5.6%), S. simulans (3.3%), S. saprophyticus (1.1%), and S. xylosus (1.1%). The results showed a total of 49 (45.4%) CNS strains that were positive by PCR. Analysis of mRNA expression by RT-PCR detected six (14.0%) CNS strains producing SEA and SEC. Conclusion: RT-PCR confirmed the toxigenic capacity of S. epidermidis and S. lugdunensis, a finding emphasizing the need for greater attention to these microorganisms when isolated from infectious processes.

    Financial support: FAPESP