The stability of antimycobacterial drugs in media used for drug susceptibility testing

Schoutrop, Esther L.M.; Brouwer, Michelle A. E.; Jenniskens, Josien C A; Ferro, Beatriz E.; Mouton, Johan W.; Aarnoutse, Rob E.; Ingen, Jakko van

doi:10.1016/j.diagmicrobio.2018.06.015

Cited by 25 publications

(18 citation statements)

References 14 publications

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“…We, therefore, propose that rifampicin MICs cannot sufficiently be measured in vitro after 10 and 14 days and that pDST results have to be considered with care for this compound. This confirms data from Schoutrop et al (2018) and Griffith and Bodily (1992), where a significant reduction of concentration in rifampicin could be demonstrated. To a lesser extent, this applies to doxycycline and rifabutin: a loss of biological activity equaling only one dilution step could be observed.…”

Section: Discussionsupporting

confidence: 91%

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Comparative analysis of phenotypic and genotypic antibiotic susceptibility patterns in Mycobacterium avium complex

Wetzstein

Kohl

Andres

et al. 2020

International Journal of Infectious Diseases

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Phenotypic (Sensititre Myco, pDST) and genotypic drug susceptibility testing (GenoType NTM DR, gDST) in M. avium complex (MAC) have become available as standardized assays, but comparable data is needed. This study aimed to investigate the phenotypic and genotypic drug susceptibility patterns in MAC clinical isolates. Methods: Overall, 98 isolates from 85 patients were included. pDST and gDST were performed on all isolates and results compared regarding specificity and sensitivity using pDST as a reference method. The impact of drug instability on pDST results was studied using a biological assay over 14 days. In addition, the evolution of antimicrobial resistance was investigated in sequential isolates of 13 patients. Results: Macrolide resistance was rare, 1.2% (95% CI 0.7-7.3) of isolates in the base cohort. No aminoglycoside resistances were found, but 14.1% of the studied isolates (95% CI 7.8-23.8) showed intermediate susceptibility. The GenoType NTM DR identified two out of four macrolide-resistant isolates. Antibiotic stability was demonstrated to be poor in rifampicin, rifabutin, and doxycycylin. Conclusions: pDST results in NTM for unstable antibiotics must be interpreted with care. A combination of pDST and gDST will be useful for the guidance of antimicrobial therapy in MAC-disease.

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Section: Discussionsupporting

confidence: 91%

“…Automated analysis is not ready yet for standard utilization in the clinical context (Rockland et al, 2018). Third, as incubation times are long, the stability of the tested antibiotics remains a technical problem, as does the interpretation of results (Schoutrop et al, 2018).…”

mentioning

confidence: 99%

Comparative analysis of phenotypic and genotypic antibiotic susceptibility patterns in Mycobacterium avium complex

Wetzstein

Kohl

Andres

et al. 2020

International Journal of Infectious Diseases

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“…Regarding the reproducibility of results obtained with the reference strain M. avium ATCC 700898, we identified a major issue linked to the low percentage of agreement obtained with clarithromycin tested in MH broth (67%) whereas it was 100% in 7H9 broth. It could be related to antibiotic instability, a problem possibly influencing MIC measurements, as pointed out recently (Schoutrop et al, 2018). Indeed, this latter study revealed an important decrease of ≥75% in clarithromycin concentration in cation-adjusted MH broth medium over 14 days of incubation at 37 • C while amikacin levels remain stable.…”

Section: Discussionsupporting

confidence: 61%

Rational Choice of Antibiotics and Media for Mycobacterium avium Complex Drug Susceptibility Testing

et al. 2020

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The Clinical and Laboratory Standards Institute recommends the use of Mueller Hinton (MH) medium to perform drug susceptibility testing (DST) of Mycobacterium avium complex (MAC) using the microdilution method. For MAC, there has been no study on the impact of media on the determination of minimum inhibitory concentrations (MICs) of antibiotics other than clarithromycin. This study aimed at determining the impact of two media used for DST of MAC and at augmenting the number of pertinent MICs for MAC species encountered in clinical practice. MICs of antibiotics used for the treatment of MAC infections were determined for 158 clinical MAC isolates (80 M. avium, 40 M. intracellulare, 35 M. chimaera, two M. yongonense and one M. timonense) in MH and 7H9 broths using the SLOMYCO Sensititre TM system (TREK Diagnostic Systems, East Grinstead, United Kingdom). The modal MICs determined in both media were the same for linezolid, moxifloxacin, rifabutin and amikacin but not for clarithromycin, rifampin and ethambutol. The kappa test for MICs converted to susceptibility categories showed an excellent agreement for clarithromycin, a moderate agreement for linezolid and a weak agreement for moxifloxacin and amikacin. For amikacin, 7H9 allowed a better distinction (fewer intermediate strains) of wild-type populations than MH. Existing breakpoints for linezolid and moxifloxacin are spread through the distribution of MICs for wild-type populations. The only breakpoints that can be used rationally are those for amikacin and clarithromycin. For amikacin, 7H9 performs better than MH, whereas both media perform equally for clarithromycin. Given that testing in 7H9, as opposed to MH, allows easier MIC measurements and yields greater reproducibility, we propose the use of 7H9 medium for DST of MAC.

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“…This would also counteract the stability issues of auranofin that might have influenced our time-kill assays. Without the addition of fresh antibiotics, it is unclear whether the microbial response might even be under estimated because of drug degradation after 7 days, which has also been shown for linezolid (29). This might also explain some of the regrowth observed after day 7.…”

Section: Discussionmentioning

confidence: 99%

“…We tested auranofin stability by preincubating uninoculated MIC plates for 7 and 14 days at 30°C (M. abscessus) and 37°C (MAC). After this incubation period, the plates were inoculated and incubated as for the susceptibility tests and then checked for higher MICs relative to the previously found MIC (29).…”

Section: Strainsmentioning

confidence: 99%

Auranofin Activity Exposes Thioredoxin Reductase as a Viable Drug Target in Mycobacterium abscessus

Ruth

Rossum

Koeken

et al. 2019

Antimicrob Agents Chemother

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Nontuberculous mycobacteria (NTM) are highly drug-resistant, opportunistic pathogens that can cause pulmonary disease. The outcomes of the currently recommended treatment regimens are poor, especially for Mycobacterium abscessus. New or repurposed drugs are direly needed. Auranofin, a gold-based antirheumatic agent, was investigated for Mycobacterium tuberculosis. Here, we test auranofin against NTM in vitro and ex vivo. We tested the susceptibility of 63 NTM isolates to auranofin using broth microdilution. Next, we assessed synergy between auranofin and antimycobacterial drugs using the checkerboard method and calculated the fractional inhibition concentration index (FICI). Using time-kill kinetics assays (TK), we assessed pharmacodynamics of auranofin alone and in combination with drug combinations showing the lowest FICIs for M. abscessus CIP 104536. A response surface analysis was used to assess synergistic interactions over time in TKs. Primary isolated macrophages were infected with M. abscessus and treated with auranofin. Finally, using KEGG Orthology, we looked for orthologues to auranofins drug target in M. tuberculosis. M. abscessus had the lowest auranofin MIC50 (2 μg/ml) among the tested NTM. The lowest average FICIs were observed between auranofin and amikacin (0.45) and linezolid (0.50). Auranofin exhibited concentration-dependent killing of M. abscessus, with >1-log killing at concentrations of >2× MIC. Only amikacin was synergistic with auranofin according to Bliss independence. Auranofin could not lower the intracellular bacterial load in macrophages. Auranofin itself may not be feasible for M. abscessus treatment, but these data point toward a promising, unutilized drug target.

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The stability of antimycobacterial drugs in media used for drug susceptibility testing

Cited by 25 publications

References 14 publications

Comparative analysis of phenotypic and genotypic antibiotic susceptibility patterns in Mycobacterium avium complex

Comparative analysis of phenotypic and genotypic antibiotic susceptibility patterns in Mycobacterium avium complex

Rational Choice of Antibiotics and Media for Mycobacterium avium Complex Drug Susceptibility Testing

Auranofin Activity Exposes Thioredoxin Reductase as a Viable Drug Target in Mycobacterium abscessus

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