Breaking antibiotic resistance in bacteria

0568027 - MBÚ 2023 RIV CZ eng A - Abstract
Balíková Novotná, Gabriela - Kameník, Zdeněk - Najmanová, Lucie - Koběrská, Markéta - Kadlčík, Stanislav - Gažák, Radek - Janata, Jiří
Breaking antibiotic resistance in bacteria.
Czech Chemical Society Symposium Series. Roč. 20, č. 6 (2022), s. 381-381. ISSN 2336-7202.
[Annual meeting of the National Institute of Virology and Bacteriology (NIVB) /1./. 30.11.2022-02.12.2022, Kutná Hora]
R&D Projects: GA MŠMT(CZ) LX22NPO5103
Institutional support: RVO:61388971
Keywords : bacterial resistance * antibiotics
OECD category: Microbiology
http://www.ccsss.cz/index.php/ccsss/issue/view/37/67

Our efforts are directed to novel ribosome-targeting antibiotics overcoming the clinically most problematic ribosome-operating resistance mechanism: Erm methyltransferase conferring cross-resistance to MLS antibiotics (Macrolides-Lincosamides-StreptograminsB). For this, we capitalized on the experience gained from almost two decades of our research on molecular mechanisms of ribosomal operating antibiotics, principles of molecular evolution of their biosynthesis an also on function of relevant resistance-mechanisms, in particular on ABCF-mediated resistance. We found that the resistance conferred by ABCF family ATPases has some surprising and unique features sharing charateristics of resistance and signaling function. Despite their ubiquity and flexibility in antibiotic-specificity and thus the risk potential, the knowledge on this protein family is fragmentary only. Two poster presentations (G. Balikova Novotna and M. Koberska) are thus presenting our results on ABCF proteins in antibiotic-producing strains as well as in pathogenic bacteria.
Regarding our summarized knowledge, we postulated lincosamides as the most promising development group of ribosome-targeting molecules: There is a low potential risk for development of ABCF-mediated resistance if compared to macrolides, the prolonged shape of lincosamide molecule is open for improving modifications at its both ends and existing natural lincosamides (lincomycin and celesticetin) provided direct inspiration for starting modification attempt. Celin is a hybrid lincosamide compounds designed based on the detailed knowledge of the biosynthesis of natural lincosamides, celesticetin and lincomycin, and their ribosomal binding site5. As expected, hybrid Celin was found to be a more effective antibiotic if compared to natural lincomycin, probably due to its extended molecular surface for interaction with ribosome. In parallel to lincomycin and its more potential chlorinated derivative clindamycin, also chlorination of Celin molecule (resulting in ClinCelin) improved antibiotic activity and even more dramatically. The in vitro MIC testing against a panel of characterized pathogenic strains proved usually 8-16x better efficiency when compared to clindamycin, the most efficient lincosamide antibiotic on the market. Also, the effect against Clostridioides difficile was documented, what is important to decrease the risk of preudomembraneous colitis, a frequent and dangerous infective complication after extensive antibiotic treatment.
In vivo testing of ClinCelin on mice and rats also provided some promising outputs. The maximal tolerated dose (MTD) testing revealed the extremely low overall toxicity for per os administration (MTD > 2000 μg/kg), similar or even better value, when compared to less efficient clindamycin. Further in vivo testing on the rat model revealed partial degradation of the antibiotic molecule, mainly the
cleavage of the ester bond connecting a salicylate moiety to the amino sugar unit. However, after a single dose per oral administration, the intact molecule prevailed in tested organs like the liver, heart and lungs, but in the feces and urine the metabolic degradation products dominated as well as in the blood serum.
MIC testing of ClinCelin against MLS resistant Staohylococcus and Streptococcus strains resulted in even more dramatic MIC decrease (even by two orders of magnitude for some tested strains), however, still clinically insufficient for many of them. In cooperation with the small company Santiago chemicals within the synergic project, dozens of Celin and ClinCelin derivatives were prepared. Notably, this „knowledge based approach“ led to remarkably high portion of the compounds exhibiting MIC values comparable to ClinCelin and several were effective even to MLS resistant strains. This project synergy considerably accelerated the preparedness for following testing on the infection in vivo models in NIVB project.
Last but not least, we are developing a bioinformatic tool for sophisticated search of functionally related groups of genes (see poster of Z. Kamenik). The complex natural products are encoded by comprehensive biosynthetic gene clusters, exhibiting “mosaic” pattern. Mosaic clusters consist of several gene subclusters coding or for biosynthesis of precursors of complex final product, or their connecting elements or even for some functionally related proteins not reflected in the final structure. Example of such functional gene subcluster is a “regulatory-resistance unit” in lincomycin cluster, coding for ABCF protein, pathway specific regulator, antibiotic efflux protein and for the methyltransferase conferring MLS resistance. We found that subclusters of similar composition are frequently present in biosynthetic gene clusters for ribosome-targeting antibiotics. Also, this bioinformatic tool can be used specifically for search of yet unkown groups of ribosome-targeting antibiotics.
Permanent Link: https://hdl.handle.net/11104/0339365