In:
Journal of Clinical Microbiology, American Society for Microbiology, Vol. 49, No. 8 ( 2011-08), p. 2884-2886
Abstract:
Constitutive or inducible clindamycin resistance can occur in beta-hemolytic streptococci due to the presence of an erm gene. The Clinical and Laboratory Standards Institute (CLSI) has recommended a disk approximation test (D-zone test) with erythromycin and clindamycin disks and a single-well broth test combining erythromycin and clindamycin for detection of inducible clindamycin resistance in staphylococci, but only a disk approximation test for the beta-hemolytic streptococci. This collaborative study assessed two different erythromycin and clindamycin concentration combinations in single wells (1 μg/ml + 0.25 μg/ml [erythromycin plus clindamycin] and 1 μg/ml + 0.5 μg/ml) with three different brands of Mueller-Hinton broth supplemented with 3% lysed horse blood for testing of frozen panels prepared for this study. All labs performed the D-zone test as described by the CLSI. A total of 155 nonduplicate streptococcal isolates (50 group A, 48 group B, 28 group C, and 29 group G isolates) were tested; 99 isolates showed inducible resistance by the D-zone test. There were some differences noted based upon the test medium. The sensitivity of the erythromycin plus clindamycin combination of 1 μg/ml + 0.25 μg/ml was 91 to 100%, while the sensitivity of the combination of 1 μg/ml + 0.5 μg/ml was 95 to 100%. Specificity overall was 98%. The slightly higher sensitivity of the combination of 1 μg/ml + 0.5 μg/ml is recommended. This study has demonstrated that a single-well microdilution test incorporating erythromycin and clindamycin in combination is a sensitive and specific indicator of inducible clindamycin resistance and could be included in routine test panels.
Type of Medium:
Online Resource
ISSN:
0095-1137
,
1098-660X
DOI:
10.1128/JCM.00912-11
Language:
English
Publisher:
American Society for Microbiology
Publication Date:
2011
detail.hit.zdb_id:
1498353-9
SSG:
12
