Amoxicillin exposure significantly increases the population and virulence of antibiotic-resistant Klebsiella pathogen in the simulated human intestinal microbiota

Abstract

Background: The extensive use and misuse of antibiotics have caused the emergence and spread of antibiotic resistance among bacterial pathogens, which is threatening to this idyllic world. The human intestinal microbiota is significant to health, while its composition and stability are easily perturbed by antibiotic exposure. However, the association between antibiotic exposure and the abnormal bloom of opportunistic pathogens in human gut, and its health implications are not fully understood. Therefore, this study investigated the influence of amoxicillin (AMX), one of the most prescribed antibiotics in human life, on human intestinal microbiota using the simulator of the human intestinal microbial ecosystem (SHIME). Results: Our results suggest that AMX exposure could cause the substantial effect on human intestinal microbiota in different colon regions, with most significant alteration in ascending colon. Intriguingly, AMX significantly increased the abundance of antibiotic-resistant Klebsiella pathogen in gut microbiota, resulting in the enrichment of human disease-related pathways. By isolation of Klebsiella strains from SHIME before and after exposure to AMX, we also observed that the virulence phenotypes of these pathogens including biofilm formation, serum resistance, and Galleria mellonella infection were significantly increased after AMX administration. The genotype analysis from whole genome sequencing indicated that the enhanced virulence phenotypes were plausibly caused by the mutations of virulence factors relevant to fimbriae, lipopolysaccharide, capsule, and siderophores. More importantly, the effects from AMX administration could not be fully recovered after two-week drug discontinuance, showing the potential long-term adverse influence of this antibiotic. Conclusions: This study for the first time demonstrates that AMX used for the treatment of bacterial infections may cause adverse effects on human health via significantly increasing population and virulence of intestinal Klebsiella opportunistic pathogen. Given that inherent resistance to β-lactam already poses a significant therapeutic challenge for Klebsiella infections, the AMX-induced virulence increasing phenomenon found in this study undoubtedly further increases its health risk.