Isolation in Brazil of nosocomial Staphylococcus aureus with reduced susceptibility to vancomycin.
OBJECTIVE
To evaluate the possible presence of vancomycin-resistant Staphylococcus aureus (VRSA) in a Brazilian hospital.


METHODS
Epidemiological and laboratory investigation of nosocomial VRSA.


METHODS
140 methicillin-resistant S aureus strains isolated between November 1998 and October 1999 were screened for susceptibility to vancomycin. The screening was carried out by using brain-heart infusion agar (BHIA) supplemented with 4, 6, and 8 microg/mL of vancomycin. The minimum inhibitory concentration (MIC) determination was carried out as standardized by the National Committee for Clinical Laboratory Standards using the broth macrodilution, agar-plate dilution, and E-test methods.


METHODS
Hospitalized patients exposed to vancomycin.


RESULTS
5 of the 140 isolates had a vancomycin MIC of 8 microg/mL by broth macrodilution, agar plate dilution, and E-test methods. Four VRSA strains were isolated from patients in a burn unit who had been treated with vancomycin for more than 30 days, and one from an orthopedic unit patient who had received vancomycin treatment for 7 days. Pulsed-field gel electrophoresis characterized four of the VRSA strains as belonging to the Brazilian endemic clone. All five strains were negative for vanA, vanB, and vanC genes by polymerase chain reaction. Transmission electron microscopy of the five strains revealed significantly thickened cell walls. One patient died due to infection caused by the VRSA strain.


CONCLUSIONS
This is the first report of isolation of VRSA in Brazil and the first report of isolation of multiple VRSA strains from one facility over a relatively short period of time. This alerts us to the possibility that VRSA may be capable of nosocomial transfer if adequate hospital infection control measures are not taken.
Oliveira
G A
GA
Faculty of Pharmaceutical Sciences, University of São Paulo, Brazil.
Dell'Aquila
A M
AM
Masiero
R L
RL
Levy
C E
CE
Gomes
M S
MS
Cui
L
L
Hiramatsu
K
K
Mamizuka
E M
EM
D000900:Anti-Bacterial Agents / Q000494:pharmacology / Q000627:therapeutic use; D001938:Brazil; D003428:Cross Infection / Q000188:drug therapy* / Q000517:prevention & control; D005260:Female; D006779:Hospitals, Public; D006801:Humans; D017053:Infection Control / Q000379:methods; D008297:Male; D016106:Methicillin Resistance; D008826:Microbial Sensitivity Tests; D013203:Staphylococcal Infections / Q000188:drug therapy* / Q000517:prevention & control; D013211:Staphylococcus aureus / Q000187:drug effects* / Q000302:isolation & purification*; D014640:Vancomycin / Q000494:pharmacology / Q000627:therapeutic use; D020713:Vancomycin Resistance
D000900:Anti-Bacterial Agents; D014640:Vancomycin