Analysis of toxin-producing and antiseptic resistance genes of methicillin-resistant Staphylococcus aureus isolated from patients in a neonatal intensive care unit.

BACKGROUND

Polymerase chain reaction--based open-reading frame typing (POT) is used to investigate nosocomial infections caused by methicillin-resistant Staphylococcus aureus (MRSA). We analyzed the relationship between POT types, nosocomial infections, and toxin-producing and antiseptic resistance genes of MRSA isolated from patients in neonatal intensive care units.

METHODS

Forty-four strains were typed by POT method. We identified toxin genes lukpvSF, tst, eta and etb, and antiseptic resistance genes qacA/B and smr.

RESULTS

Fourteen POT types were identified; 43 strains were considered community-acquired MRSA. Twenty-eight strains were nosocomial. Eleven strains were positive for toxin-producing genes (9 for tst and 2 for lukpvSF) and classified into 6 POT types. Six strains were positive for antiseptic resistance genes (qacA/B) and classified into 2 POT types. Overall, 11 MRSA isolates were positive for toxin-producing or antiseptic resistance genes (6 nosocomial, 5 non-nosocomial). Strains with POT types 106-9-80 (2 strains) and 106-221-120 (4 strains) were positive for tst and qacA/B, equally divided between nosocomial and non-nosocomial.

DISCUSSION: Some POT types are prone to nosocomial infections. However, no clear association between toxin-producing or antiseptic resistance genes and nosocomial infections was observed.

CONCLUSIONS

Factors other than toxin production and resistance to disinfectants may be related to nosocomial infection.