Molecular characterization of methicillin-resistant coagulase-negative staphylococci from a neonatal intensive care unit.
OBJECTIVE
To evaluate clonal dissemination of methicillin-resistant coagulase-negative staphylococci (CNS).


METHODS
Neonatal intensive care unit of a 180-bed, university-affiliated general hospital.


METHODS
Neonates admitted to the neonatal intensive care unit between March 1999 and October 2000, from whom CNS were isolated as a unique pathogen. Patients from other wards from whom epidemiologically unrelated staphylococci strains were obtained served as control-patients.


METHODS
Conventional methods were used for phenotypic characterization of CNS. Methicillin resistance was determined by mecA polymerase chain reaction (PCR) amplification. Genotypic characterization was done by random amplification of DNA with degenerated primers (RAPD) and repetitive element sequence-based PCR (rep-PCR).


RESULTS
Forty methicillin-resistant CNS isolates obtained from neonates were characterized as Staphylococcus epidermidis (33), S. hominis (5), S. warneri (1), and S. auricularis (1). Both RAPD and rep-PCR indicated the presence of 4 different clones among the 33 S. epidermidis isolates. In turn, the 4 randomly selected, epidemiologically unrelated methicillin-resistant CNS strains obtained from control-patients showed 3 new profiles by RAPD and 2 by rep-PCR, which differed from the corresponding patterns mentioned earlier. Persistence of S. hominis in a neonate could be assessed by both genotypic techniques.


CONCLUSIONS
The molecular characterization of the methicillin-resistant CNS studied indicated dissemination of one particular methicillin-resistant CNS clone among the neonates in the ward studied. Although RAPD showed a superior power to discriminate among methicillin-resistant CNS isolates, both RAPD and rep-PCR detected intraspecific and interspecific genomic diversity.
Institute of Cellular and Molecular Biology of Rosario, School of Biochemistry and Pharmacy, National University of Rosario, Argentina.
Isabel
I
Bogado
Adriana
A
Limansky
Emma
E
Sutich
Patricia
P
Marchiaro
Marta
M
Marzi
Juan
J
Putero
Alejandro
A
Viale
D001118:Argentina / Q000453:epidemiology; D015373:Bacterial Typing Techniques / Q000379:methods*; D016022:Case-Control Studies; D003428:Cross Infection / Q000453:epidemiology / Q000382:microbiology; D006801:Humans; D007231:Infant, Newborn; D007363:Intensive Care Units, Neonatal; D016106:Methicillin Resistance / Q000235:genetics*; D016133:Polymerase Chain Reaction / Q000379:methods*; D019105:Random Amplified Polymorphic DNA Technique; D013203:Staphylococcal Infections / Q000453:epidemiology / Q000382:microbiology; D013210:Staphylococcus / Q000145:classification* / Q000235:genetics