Phenotypic detection of inducible clindamycin resistance among <i> Staphylococcus aureus</i> isolates by using the lower limit of recommended inter-disk distance
<b>Context:</b> Clindamycin is one of the important alternative antibiotics in the therapy of <i>Staphylococcus aureus</i>, particularly in methicillin-resistant <i>S. aureus</i> (MRSA) infections. Inducible clindamycin resistance (iMLS<sub> B</sub> -...
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| Main Authors: | , , , , |
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| Format: | Book |
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Wolters Kluwer Medknow Publications,
2008-07-01T00:00:00Z.
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| Online Access: | Connect to this object online. |
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| Summary: | <b>Context:</b> Clindamycin is one of the important alternative antibiotics in the therapy of <i>Staphylococcus aureus</i>, particularly in methicillin-resistant <i>S. aureus</i> (MRSA) infections. Inducible clindamycin resistance (iMLS<sub> B</sub> - inducible Macrolide-Lincosamide-Streptogramin B resistance) is a critical factor in antimicrobial susceptibility testing. <b> Aims:</b> To know the rate of inducible clindamycin resistance among clinical isolates of <i>Staphylococcus aureus</i> in our hospital by Disk approximation test (D-test) using the average recommended inter-disk distance and comparing the results with that of D-test using the lower limit of recommended inter-disk distance. <b> Materials and Methods:</b> A total of 51 erythromycin-resistant and clindamycin-susceptible <i>S. aureus </i>isolates were subjected to disk approximation testing with 21 ± 1 mm and 15 mm edge-to-edge distance between the clindamycin and erythromycin disks. <b> Statistical Methods:</b> Z-test levels. <b> Results:</b> Among 51 erythromycin-resistant and clindamycin-susceptible <i>S. aureus </i>isolates, 25 (49%) were recorded as inducible clindamycin resistant by D-test with 21 ± 1 mm edge-to-edge distance between the clindamycin and erythromycin disks. When we re-tested all the 51 strains by D-test with 15 mm inter-disk distance, we identified 14% more iMLS<sub> B</sub> strains previously reported as D-test negative. Z-test for MRSA indicates that 15 mm edge-to-edge distance has significant advantage. <b> Conclusions:</b> Since the incidence of inducible clindamycin resistance is high (63% in our study), accurate identification of inducible clindamycin resistance is important to prevent therapeutic failure in infections caused by these strains. We suggest the use of D-test with 15 mm edge-to-edge inter-disk distance for detecting iMLS<sub> B</sub> . |
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| Item Description: | 0377-4929 |