Detection of inducible clindamycin resistance in staphylococci by broth microdilution using erythromycin-clindamycin combination wells.
A study conducted by 11 laboratories investigated the ability of four combinations of erythromycin (ERY) and clindamycin (CC) (ERY and CC at 4 and 0.5, 6 and 1, 8 and 1.5, and 0.5 and 2 microg/ml) in a single well of a broth microdilution panel to predict the presence of inducible CC resistance. Each laboratory tested approximately 30 Staphylococcus aureus isolates and 20 coagulase-negative staphylococcus (CoNS) isolates in a panel using cation-adjusted Mueller-Hinton broth from three different manufacturers. Only the strains resistant to ERY and those susceptible or intermediate to CC were included in the analysis (S. aureus, n = 333; CoNS, n = 97). Results of the D-zone test were used as the gold standard. After an 18-h incubation, the combination of 4 microg/ml ERY and 0.5 microg/ml CC performed the best, with 98 to 100% sensitivity and 100% specificity for both organism groups. After a 24-h incubation, the ERY-CC combinations of 4 and 0.5, 6 and 1, and 8 and 1.5 microg/ml correlated well with the D-zone test.
Swenson
Jana M
JM
Antimicrobial Resistance Team, Division of Healthcare Quality Promotion, Centers for Disease Control and Prevention, Atlanta, GA 30333, USA. jms1@cdc.gov
Brasso
William B
WB
Ferraro
Mary Jane
MJ
Hardy
Dwight J
DJ
Knapp
Cynthia C
CC
McDougal
Linda K
LK
Reller
L Barth
LB
Sader
Helio S
HS
Shortridge
Dee
D
Skov
Robert
R
Weinstein
Melvin P
MP
Zimmer
Barbara L
BL
Patel
Jean B
JB
D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D002981:Clindamycin / Q000494:pharmacology*; D003470:Culture Media / Q000737:chemistry; D024881:Drug Resistance, Bacterial; D004917:Erythromycin / Q000494:pharmacology*; D005786:Gene Expression Regulation / Q000187:drug effects; D008826:Microbial Sensitivity Tests / Q000379:methods*; D012680:Sensitivity and Specificity; D013210:Staphylococcus / Q000187:drug effects*
D000900:Anti-Bacterial Agents; D003470:Culture Media; D002981:Clindamycin; D004917:Erythromycin