The potential role of drug transporters and amikacin modifying enzymes in M. avium

• DOI: 10.1016/j.jgar.2023.07.007
• Publication Date: 2023-07-13T17:07:15Z
• Authors: Jodie A. Schildkraut; Jordy P.M. Coolen; Carolien Ruesen; Jeroen J.M.W. van...; Laura Edo Aceña; Heiman F.L. Wertheim; Robert S. Jansen; Jan B. Koenderink; Lindsey H.M. te B...; Jakko van Ingen
• Keywords: tolerance; Radboudumc 4: lnfectious Diseases and Global Health Pharmacology-Toxicology; Berberine; Antibiotic resistance; Radboud University Medical Center; Membrane Transport Proteins; RNA sequencing; Mycobacterium tuberculosis; Mycobacterium avium Complex; Microbiology; Radboudumc 4: lnfectious Diseases and Global Health Medical Microbiology; QR1-502; 3. Good health; Anti-Bacterial Agents; Ecological Microbiology; Clarithromycin; Humans; Radboudumc 4: lnfectious Diseases and Global Health Clinical Pharmacy; ATP-Binding Cassette Transporters; Radboudumc 4: lnfectious Diseases and Global Health Pulmonary Diseases; Tolerance; Amikacin; Nontuberculous mycobacteria; Ethambutol; Mycobacterium avium

Mycobacterium avium (M. avium) complex bacteria cause opportunistic infections in humans. Treatment yields cure rates of 60% and consists of a macrolide, a rifamycin, and ethambutol, and in severe cases, amikacin. Mechanisms of antibiotic tolerance remain mostly unknown. Therefore, we studied the contribution of efflux and amikacin modification to antibiotic susceptibility.We characterised M. avium ABC transporters and studied their expression together with other transporters following exposure to clarithromycin, amikacin, ethambutol, and rifampicin. We determined the effect of combining the efflux pump inhibitors berberine, verapamil and CCCP (carbonyl cyanide m-chlorophenyl hydrazone), to study the role of efflux on susceptibility. Finally, we studied the modification of amikacin by M. avium using metabolomic analysis.Clustering shows conservation between M. avium and M. tuberculosis and transporters from most bacterial subfamilies (2-6, 7a/b, 10-12) were found. The largest number of transporter encoding genes was up-regulated after clarithromycin exposure, and the least following amikacin exposure. Only berberine increased the susceptibility to clarithromycin. Finally, because of the limited effect of amikacin on transporter expression, we studied amikacin modification and showed that M. avium, in contrast to M. abscessus, is not able to modify amikacin.We show that M. avium carries ABC transporters from all major families important for antibiotic efflux, including homologues shown to have affinity for drugs included in treatment. Efflux inhibition in M. avium can increase susceptibility, but this effect is efflux pump inhibitor- and antibiotic-specific. Finally, the lack of amikacin modifying activity in M. avium is important for its activity.