Molecular study of methicillin-resistant Staphylococcus aureus isolates at a neonatal high-risk unit in Merida,...

Methicillin-resistant Staphylococcus aureus (MRSA) is a multiresistant microorganisms which holds first place in the world as a nosocomial pathogen. Special attention has therefore been directed to specific nosocomial surveillance systems and strict infection control measures for this microorganism in which the microbiological laboratory plays an important role by applying phenotypic and genotypic methods that permit establishing their epidemiological relationship especially in hospital outbreaks. In the present study the general objective was to study MRSA strains isolated from neonates with nosocomial infections and from healthcare personnel working in the Neonatal High Risk Unit (NHRU) of the Andes University Hospital Autonomous Institute (AUHAI) in Mérida, Venezuela.

Forty-three S. aureus isolates were analyzed by phenotypic and genotypic methods.

In these strains, antibiotypes resistant to oxacillin, gentamicin, erythromycin, and tobramycin predominated (50%). The greater percentage of MRSA strains isolated from health personnel as well as two neonates were described as pulse types Ia and Ib, belonging to phage group II, containing type IV SCCmecA and resistant to macrolides and aminoglycosides and sensitive to clindamycin and trimethoprim-sulfamethoxazole.

This is the first reported case of SCCmecA type IV MRSA found in the NHRU of the AUHAI.