Oreochromis mossambicus (Peters 1852) (Tilapia) is one of the most consumed fish globally. Tilapia thrives well inenvironments polluted by urban waste, which invariably contain antibiotic-resistant bacteria and antibiotic resistance genes(ARGs). Thus, Tilapia surviving in such polluted environments may serve as a potential source for dissemination of ARGs.To investigate this, we isolated bacterial strains from gut of Tilapia found in polluted rivers and lakes near Pune, India, andstudied the prevalence of resistance genes bymolecularmethods. A total of 91 bacterial strains were obtained, which includefish pathogens and human pathogens such as Aeromonas hydrophila, Klebsiella pneumoniae, E. coli, Serratia marcescens,Enterobacter spp. and Shigella spp. Overall the prevalence of class 1 integrons, class 2 integrons, extended-spectrum betalactamases(ESBLs) bla_{CTX-M}, bla_{SHV} and aac(6')-Ib-cr gene was 38%, 24%, 38%, 31% and 31% respectively. Forty-twopercent of the Enterobacteriaceae strains carried bla_{CTX-M} gene, which is a common ESBL gene in clinics. The studydemonstrates that tilapia found in the polluted waters can serve as reservoirs and an alternative route for human exposure toclinically important ARG-carrying bacteria. The consumption and handling of these fish may pose a potential health risk.

The human microbiota plays a crucial role in educating the immune system and influencing host health right since birth.Various maternal factors along with the vertical microbial transfer from the mother, as well as the horizontal environmentaltransmission and internal factors relating to the infant, play a crucial role in modulating the gut microbiota. The early lifemicroflora is highly unstable and undergoes dynamic changes during the first few years, converging towards a morestabilized adult microbiota by co-evolving with the host by the age of 3–4 years. Microbiota studies have underlined therole of dysbiosis in developing several metabolic disorders like obesity, diabetes and immune-related disorders like asthma,to name a few. Thus, understanding early life microbial composition and various factors affecting the microbial communitywill provide a platform for developing strategies/techniques to maintain host health by restoring gut microbial flora. Thisreview focuses on the factors that affect the microbial composition of the foetus in utero, during birth, infancy throughchildhood.