Project description:Mycobacterium abscessus [M. abscessus (sensu lato) or M. abscessus group] comprises three closely related taxa with taxonomic status under revision: M. abscessus sensu stricto, M. bolletii and M. massiliense. We describe here a simple, robust and cost effective PCR-based method for distinguishing among M. abscessus, M. massiliense and bolletii. Based on the M. abscessus ATCC 19977T genome, discriminatory regions were identified between M. abscessus and M. massiliense from array-based comparative genomic hybridization. A typing scheme using PCR primers designed for four of these locations was applied to 46 well-characterized clinical isolates comprising 29 M. abscessus, 15 M. massiliense and 2 M. bolletii previously identified by multi-target sequencing. Interestingly, 2 isolates unequivocally identified as M. massiliense were shown to have a full length erm(41) instead of the expected gene deletion and showed inducible clarithromycin resistance after 14 days. We propose using this PCR-based typing scheme combined with erm(41) PCR for a straightforward identification of M. abscessus, M. massiliense and M. bolletii and assessment of inducible clarithromycin resistance. This method can be easily implemented into a routine workflow providing subspecies level identification within 24 hours of isolation of M. abscessus group.
Project description:Mycobacterium abscessus [M. abscessus (sensu lato) or M. abscessus group] comprises three closely related taxa with taxonomic status under revision: M. abscessus sensu stricto, M. bolletii and M. massiliense. We describe here a simple, robust and cost effective PCR-based method for distinguishing among M. abscessus, M. massiliense and bolletii. Based on the M. abscessus ATCC 19977T genome, discriminatory regions were identified between M. abscessus and M. massiliense from array-based comparative genomic hybridization. A typing scheme using PCR primers designed for four of these locations was applied to 46 well-characterized clinical isolates comprising 29 M. abscessus, 15 M. massiliense and 2 M. bolletii previously identified by multi-target sequencing. Interestingly, 2 isolates unequivocally identified as M. massiliense were shown to have a full length erm(41) instead of the expected gene deletion and showed inducible clarithromycin resistance after 14 days. We propose using this PCR-based typing scheme combined with erm(41) PCR for a straightforward identification of M. abscessus, M. massiliense and M. bolletii and assessment of inducible clarithromycin resistance. This method can be easily implemented into a routine workflow providing subspecies level identification within 24 hours of isolation of M. abscessus group. Two-color CGH with 4 independent Mycobacterium clinical isolates and the M massiliense type strain (CCUG 48898) labeled with Cy3 were cohybridized with the M abscessus type strain (ATCC 19977) labeled with Cy5 on a tiling array designed against the M abscessus type strain
Project description:Mycobacterium abscessus is an opportunistic pathogen notorious for its resistance to most classes of antibiotics and low cure rates. In addition to the highly impermeable mycomembrane, M. abscessus carries an array of shared and species-specific defence mechanisms. However, it remains unknown whether M. abscessus’ antibiotic stress response is fine-tuned or an all-or-nothing response. A deeper understanding of underlying resistance and tolerance mechanisms is pivotal in development of targeted therapeutic regimens. We elucidate the transcriptomic response of M. abscessus to antibiotics recommended in treatment guidelines. The M. abscessus ATCC 19977 strain was used. Bacteria were subjected to sub-inhibitory concentrations of drugs for 4- and 24-hours, followed by RNA sequencing. In addition, time-kill kinetic analysis was performed using bacteria after pre-exposure to clarithromycin, amikacin or tigecycline for 24-hours. Lastly, Pan-genome analysis of 35 strains from all three subspecies was performed. Mycobacterium abscessus shows both drug-specific and communal transcriptomic responses to antibiotic exposure. Key features of its tolerance to antibiotics are drug-specific converting enzymes, target protection and shifts in its respiratory chain and metabolic state. The observed transcriptomic responses are likely not strain-specific, as genes involved in tolerance are found in all included strains, with the exception of erm(41) in M. abscessus subspecies massiliense. Due to the communal response elicited by ribosomal-targeting antibiotics, exposure to any of these drugs rapidly induces tolerance mechanisms that decrease susceptibility to ribosome-targeting drugs from multiple classes. Screening high-risk patients (e.g. those with bronchiectasis) for M. abscessus infection prior to starting macrolide or aminoglycoside maintenance therapy is warranted.
Project description:Background: Mycobacterium avium complex (MAC) bacteria cause opportunistic infections in humans. Treatment yields cure rates of 60% and is comprised of a macrolide, a rifamycin and ethambutol; and in severe cases amikacin. Mechanisms of antibiotic tolerance remain mostly unknown. To elucidate these mechanisms, we studied the transcriptomic response to antibiotics and investigated the contribution of efflux and amikacin modification to susceptibility. Methods: M. avium was subjected to subinhibitory concentrations of clarithromycin, amikacin, ethambutol and rifampicin followed by RNA sequencing. Based thereupon, we characterized M. avium efflux pumps and performed time-kill kinetic analysis using each antibiotic in combination with the efflux pump inhibitors (EPIs) berberine, verapamil and CCCP to study the role of efflux on susceptibility. Finally, we studied the modification of amikacin by M. avium using metabolomic analysis. Results: Changes in respiratory state and changes in ribosome binding and protein folding likely contribute to clarithromycin and amikacin tolerance, respectively. No clear drug-specific mechanisms of tolerance are found for ethambutol and rifampicin. Of the EPIs, only berberine increased the susceptibility to rifampicin and clarithromycin. Finally, we show that M. avium, in contrast to M. abscessus, is not able to modify amikacin. Conclusion: M. avium likely relies on a combination of drug-specific and generic mechanisms of antibiotic tolerance including changes in respiratory and metabolic state in addition to drug efflux and target modification. Efflux inhibition can increase susceptibility but this effect is EPI and antibiotic specific. Finally, the lack of amikacin modifying activity in M. avium is important for its activity.
Project description:Identifying resistance mutations in a drug target provides crucial information. Lentiviral transduction creates multiple types of mutations due to the error-prone nature of the HIV-1 reverse transcriptase (RT) and we show this property can be leveraged to identify mutations that confer resistance to targeted anti-cancer drugs, a technique we term “LentiMutate”. First, we improved LentiMutate by making the lentiviral RT more error-prone. Next, we applied this technique to two anti-cancer drugs, imatinib and AMG 510. We find novel deletions in BCR-ABL that confer resistance to BCR-ABL inhibitors and point mutations in the AMG 510 binding pocket or oncogenic non-G12C mutations, in KRAS-G12C or wild-type KRAS, respectively, that confer resistance to AMG 510. LentiMutate may prove highly valuable to clinical and preclinical cancer drug development
Project description:Identifying resistance mutations in a drug target provides crucial information. Lentiviral transduction creates multiple types of mutations due to the error-prone nature of the HIV-1 reverse transcriptase (RT) and we show this property can be leveraged to identify mutations that confer resistance to targeted anti-cancer drugs, a technique we term “LentiMutate”. First, we improved LentiMutate by making the lentiviral RT more error-prone. Next, we applied this technique to two anti-cancer drugs, imatinib and AMG 510. We find novel deletions in BCR-ABL that confer resistance to BCR-ABL inhibitors and point mutations in the AMG 510 binding pocket or oncogenic non-G12C mutations, in KRAS-G12C or wild-type KRAS, respectively, that confer resistance to AMG 510. LentiMutate may prove highly valuable to clinical and preclinical cancer drug development
2021-07-25 | GSE164661 | GEO
Project description:Clarithromycin resistance in Bacillus anthracis
Project description:Identifying resistance mutations in a drug target provides crucial information. Lentiviral transduction creates multiple types of mutations due to the error-prone nature of the HIV-1 reverse transcriptase (RT). We optimized and leveraged this property to identify drug resistance mutations, a technique we term LentiMutate. After validating this technique by identifying clinically relevant EGFR resistance mutations, we applied this technique to two additional anti-cancer drugs, imatinib and AMG 510. We find novel deletions in BCR-ABL1 that confer resistance to BCR-ABL1 inhibitors and point mutations in the AMG 510 binding pocket or oncogenic non-G12C mutations, in KRAS-G12C or wild-type KRAS, respectively, that confer resistance to AMG 510. LentiMutate may prove highly valuable to clinical and preclinical cancer drug development.