Bacteremia caused by staphylococci with inducible vancomycin heteroresistance.
The clinical significance of bacteremia due to vancomycin-heteroresistant staphylococci and a rapid laboratory screening method were examined; 203 strains of staphylococci isolated from patients with clinically significant bacteremia were screened by the disk-agar method with use of vancomycin-salt agar to demonstrate satellitism around an aztreonam disk as well as by conventional population screening. Eighteen isolates (three Staphylococcus aureus and 15 coagulase-negative staphylococci) were shown to be heteroresistant to vancomycin. A case-control clinical study showed that the interval between admission and bacteremia, admission to the intensive care unit, prior use of vancomycin and/or beta-lactams, and isolation of methicillin-resistant staphylococci were significantly more common among patients with bacteremia due to staphylococci with heteroresistance to vancomycin; these patients had an overall mortality of 44.4%. The use of vancomycin and admission to the intensive care unit were independently significant risk factors on multivariate analysis. Vancomycin heteroresistance is inducible by salt and beta-lactams. Indiscriminate sequential use of beta-lactams and glycopeptides may facilitate the emergence of glycopeptide resistance.
Wong
S S
SS
Department of Microbiology, The University of Hong Kong, Queen Mary Hospital, Hong Kong.
Ho
P L
PL
Woo
P C
PC
Yuen
K Y
KY
D000293:Adolescent; D000328:Adult; D000368:Aged; D016470:Bacteremia / Q000188:drug therapy / Q000209:etiology* / Q000401:mortality; D002675:Child, Preschool; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D016106:Methicillin Resistance; D008875:Middle Aged; D012307:Risk Factors; D013210:Staphylococcus / Q000187:drug effects*; D020713:Vancomycin Resistance