Microbiota of the Gut: Antibiotic-Induced Dysbiosis and the Adverse Effects on Human Health

A healthy gut microbial community is essential for homeostasis in mammals. A symbiotic relationship between host and microbe is essential in developing the immune system, providing biomolecules and generating energy through utilisation of indigestible compounds. The diversity of the gut microbiota is altered following antibiotic treatments, the effect this has on the health and wellbeing of the host has long been underestimated and is now the subject of intense debate. Antibiotics facilitate the selection of energy harvesting microbes within the gut and hence heavily influence the gaining of weight and may be contributing more than we anticipated to the modern obesity epidemic. These changes to the bacterial composition of the gut, dysbiosis are caused by elevated oxygen levels within the gut that promotes the propagation of facultative anaerobic Proteobacteria, a condition associated with inflammation and cancer. Additionally, the altered oxygenated intestinal climate allows the growth of aerobic pathogens, conveying clinically relevant resistance genes on highly transmissible mobile elements between communities or acquiring them from commensal bacteria, in turn aiding the spread of antibiotic resistance. Here we discuss the indirect pleotropic effects antibiotics have on the microbial community and environment of the gut leading to hidden adverse implications to human health.