Giuseppe
Emeritus
[Source: Antimicrobial Agents and Chemotherapy, full text: (LINK). Abstract, edited.]
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Susceptibility testing of extensively drug resistant and pre-extensively drug resistant Mycobacterium tuberculosis against levofloxacin, linezolid, and amoxicillin/clavulanate
Imran Ahmed 1, Kauser Jabeen 1, Raunaq Inayat 1 and Rumina Hasan 1,#
Author Affiliations: <SUP>1</SUP>Department of Pathology and Microbiology, Aga Khan University Hospital, Karachi, Pakistan
ABSTRACT
Background:
Pakistan is a high burden country for tuberculosis (TB). Emergence and increasing incidence of extensively drug resistant (XDR) TB has been reported from Pakistan. Similarly, rates of MDR-TB with fluoroquinolone resistance (pre-XDR) are also increasing. To treat these infections, local drug susceptibility pattern of alternate anti-tuberculosis agents including levofloxacin (LVX), linezolid (LZD) & amoxicillin/clavulanate (AMC) is urgently needed.
Objective:
To determine the susceptibility frequencies of drug resistant Mycobacterium tuberculosis (DR-MTB) against levofloxacin, linezolid and amoxicillin/clavulanate.
Methods:
All susceptibilities were performed on Middlebrook 7H10 agar. Critical concentration was used for LVX (1μg/ml) whereas minimum inhibitory concentrations (MICs) were performed for LZD and AMC. Mycobacterium tuberculosis H37Rv was used as a control strain.
Results:
A total of 102 MTB isolates (XDR: 59; pre-XDR: 43) were tested. Resistance to LVX was observed in 91.2% (93/102). Using an MIC value of 0.5 μg/ml as cutoff, resistance to LZD (MIC ≥1 μg/ml) was noted in 5.9% (6/102). Although sensitivity breakpoints are not established for AMC, the MIC values were high (>16μg/ml) in 97.1% (99/102).
Conclusion:
Our results demonstrate that LZD may be effective for treatment of XDR and pre-XDR cases from Pakistan. High resistance rates against LVX in our study suggest use of this drug with caution for DR-TB cases from this area. Drug susceptibility testing against LVX and AMC may be helpful in complicated and difficult to manage cases.
FOOTNOTES
# Corresponding author: rumina.hasan@aku.edu
Copyright ? 2013, American Society for Microbiology. All Rights Reserved.
-Imran Ahmed 1, Kauser Jabeen 1, Raunaq Inayat 1 and Rumina Hasan 1,#
Author Affiliations: <SUP>1</SUP>Department of Pathology and Microbiology, Aga Khan University Hospital, Karachi, Pakistan
ABSTRACT
Background:
Pakistan is a high burden country for tuberculosis (TB). Emergence and increasing incidence of extensively drug resistant (XDR) TB has been reported from Pakistan. Similarly, rates of MDR-TB with fluoroquinolone resistance (pre-XDR) are also increasing. To treat these infections, local drug susceptibility pattern of alternate anti-tuberculosis agents including levofloxacin (LVX), linezolid (LZD) & amoxicillin/clavulanate (AMC) is urgently needed.
Objective:
To determine the susceptibility frequencies of drug resistant Mycobacterium tuberculosis (DR-MTB) against levofloxacin, linezolid and amoxicillin/clavulanate.
Methods:
All susceptibilities were performed on Middlebrook 7H10 agar. Critical concentration was used for LVX (1μg/ml) whereas minimum inhibitory concentrations (MICs) were performed for LZD and AMC. Mycobacterium tuberculosis H37Rv was used as a control strain.
Results:
A total of 102 MTB isolates (XDR: 59; pre-XDR: 43) were tested. Resistance to LVX was observed in 91.2% (93/102). Using an MIC value of 0.5 μg/ml as cutoff, resistance to LZD (MIC ≥1 μg/ml) was noted in 5.9% (6/102). Although sensitivity breakpoints are not established for AMC, the MIC values were high (>16μg/ml) in 97.1% (99/102).
Conclusion:
Our results demonstrate that LZD may be effective for treatment of XDR and pre-XDR cases from Pakistan. High resistance rates against LVX in our study suggest use of this drug with caution for DR-TB cases from this area. Drug susceptibility testing against LVX and AMC may be helpful in complicated and difficult to manage cases.
FOOTNOTES
# Corresponding author: rumina.hasan@aku.edu
Copyright ? 2013, American Society for Microbiology. All Rights Reserved.
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