A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species
Introduction: Erythromycin resistant Staphylococcus isolates with inducible resistance appear sensitive to clindamycin in in?vitro sensitivity testing. If clindamycin is used for treatment of such isolates, selection for constitutive mutants may lead to clinical failure. Current study was conducted...
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| Format: | Article |
| Language: | English |
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Manipal College of Medical Sciences, Pokhara
2015-05-01
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| Series: | Asian Journal of Medical Sciences |
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| Online Access: | https://www.nepjol.info/index.php/AJMS/article/view/11811 |
| _version_ | 1829104840335163392 |
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| author | Fatima Khan |
| author_facet | Fatima Khan |
| author_sort | Fatima Khan |
| collection | DOAJ |
| description | Introduction: Erythromycin resistant Staphylococcus isolates with inducible resistance appear sensitive to clindamycin in in?vitro sensitivity testing. If clindamycin is used for treatment of such isolates, selection for constitutive mutants may lead to clinical failure. Current study was conducted to detect the presence of inducible clindamycin resistance in erythromycin resistant Staphylococcus isolates by disk diffusion method (D test). To correlate clindamycin resistance phenotypes with minimum inhibitory concentrations (MICs) of clindamycin, erythromycin, oxacillin and vancomycin among the isolates. To correlate various resistance phenotypes with methicillin resistance.
Material and Methods: 150 non duplicate isolates of Staphylococcus species were identified and antibiotic susceptibility testing was done using Kirby Bauer’s disc diffusion method. MICs were determined using E?test for oxacillin, vancomycin, clindamycin and erythromycin using E?test strips (Himedia)
Results: Among 150 staphylococcus clinical isolates, 96 were of S. aureus and 54 were coagulase negative Staphylococci (CONS). About 81.2% of the S.aureus isolates and 72.2% of the CONS were found to be methicillin resistant. Inducible clindamycin resistance was found in 39.3% of the isolates, constitutive resistance phenotype in 48% while 12.7% demonstrated MS phenotype. 18% and 11.3% of all the isolates had MICs for clindamycin between 0.01?0.06 μg/ml and 0.06?0.1 respectively. 12.5% had MIC ranging from 4?8 μg/ml while 58% had MIC > 8 μg/ml. Constitutive resistant phenotype (cMLS) was the predominant phenotype in methicillin resistant isolates. MS phenotype was the predominant among MSSA (methicillin sensitive S. aureus) while MSCNS (methicillin sensitive CONS) cMLS (46.7%) predominated. MIC of all erythromycin resistant isolates were ≥ 240 μg/ml. Nearly 16.7% of the cMLS and 57.9% of MS isolates were found to be oxacillin sensitive and 83% of iMLS and 83.3% of MS phenotype isolates were oxacillin resistant on MIC testing. 47.2% of cMLS and 73.6% of MS isolates had MIC ≤ 2 μg/ml for vancomycin and 52.7% of cMLS and 26.3% of MS isolates had MICs in intermediate range for vancomycin.
Conclusions: D?testing might help clinicians to decide whether to use clindamycin in Staphylococcal infections when erythromycin resistance is present. Determination of MICs help to identify exact sensitivity profile of isolates in cases where clinical failure occurs due to misleading disk diffusion tests. |
| first_indexed | 2024-12-12T05:55:43Z |
| format | Article |
| id | doaj.art-eb5e89572fa74e5485f6288c8a0b278b |
| institution | Directory Open Access Journal |
| issn | 2467-9100 2091-0576 |
| language | English |
| last_indexed | 2024-12-12T05:55:43Z |
| publishDate | 2015-05-01 |
| publisher | Manipal College of Medical Sciences, Pokhara |
| record_format | Article |
| series | Asian Journal of Medical Sciences |
| spelling | doaj.art-eb5e89572fa74e5485f6288c8a0b278b2022-12-22T00:35:34ZengManipal College of Medical Sciences, PokharaAsian Journal of Medical Sciences2467-91002091-05762015-05-01664852https://doi.org/10.3126/ajms.v6i6.11811A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus speciesFatima Khan 0Department of Microbiology, Jawaharlal Nehru Medical College and Hospital, AMU, Aligarh, U.P.Introduction: Erythromycin resistant Staphylococcus isolates with inducible resistance appear sensitive to clindamycin in in?vitro sensitivity testing. If clindamycin is used for treatment of such isolates, selection for constitutive mutants may lead to clinical failure. Current study was conducted to detect the presence of inducible clindamycin resistance in erythromycin resistant Staphylococcus isolates by disk diffusion method (D test). To correlate clindamycin resistance phenotypes with minimum inhibitory concentrations (MICs) of clindamycin, erythromycin, oxacillin and vancomycin among the isolates. To correlate various resistance phenotypes with methicillin resistance. Material and Methods: 150 non duplicate isolates of Staphylococcus species were identified and antibiotic susceptibility testing was done using Kirby Bauer’s disc diffusion method. MICs were determined using E?test for oxacillin, vancomycin, clindamycin and erythromycin using E?test strips (Himedia) Results: Among 150 staphylococcus clinical isolates, 96 were of S. aureus and 54 were coagulase negative Staphylococci (CONS). About 81.2% of the S.aureus isolates and 72.2% of the CONS were found to be methicillin resistant. Inducible clindamycin resistance was found in 39.3% of the isolates, constitutive resistance phenotype in 48% while 12.7% demonstrated MS phenotype. 18% and 11.3% of all the isolates had MICs for clindamycin between 0.01?0.06 μg/ml and 0.06?0.1 respectively. 12.5% had MIC ranging from 4?8 μg/ml while 58% had MIC > 8 μg/ml. Constitutive resistant phenotype (cMLS) was the predominant phenotype in methicillin resistant isolates. MS phenotype was the predominant among MSSA (methicillin sensitive S. aureus) while MSCNS (methicillin sensitive CONS) cMLS (46.7%) predominated. MIC of all erythromycin resistant isolates were ≥ 240 μg/ml. Nearly 16.7% of the cMLS and 57.9% of MS isolates were found to be oxacillin sensitive and 83% of iMLS and 83.3% of MS phenotype isolates were oxacillin resistant on MIC testing. 47.2% of cMLS and 73.6% of MS isolates had MIC ≤ 2 μg/ml for vancomycin and 52.7% of cMLS and 26.3% of MS isolates had MICs in intermediate range for vancomycin. Conclusions: D?testing might help clinicians to decide whether to use clindamycin in Staphylococcal infections when erythromycin resistance is present. Determination of MICs help to identify exact sensitivity profile of isolates in cases where clinical failure occurs due to misleading disk diffusion tests.https://www.nepjol.info/index.php/AJMS/article/view/11811staphylococcuserythromycinclindamycinmrsad-test |
| spellingShingle | Fatima Khan A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species Asian Journal of Medical Sciences staphylococcus erythromycin clindamycin mrsa d-test |
| title | A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species |
| title_full | A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species |
| title_fullStr | A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species |
| title_full_unstemmed | A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species |
| title_short | A study of inducible clindamycin resistance in erythromycin resistant clinical isolates of Staphylococcus species |
| title_sort | study of inducible clindamycin resistance in erythromycin resistant clinical isolates of staphylococcus species |
| topic | staphylococcus erythromycin clindamycin mrsa d-test |
| url | https://www.nepjol.info/index.php/AJMS/article/view/11811 |
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