The Evolution of Antibiotic Resistance in Bacillus thuringiensis hitchhikes the pathogenicity: A silent threat
by Joy Bose | Srijan Seal | Aritra Bhattacharya | Imroze Khan | Ashoka University, Haryana, India | Ashoka University, Haryana, India | Texas A&M University | Ashoka University, Haryana, India
Abstract ID: 215
Event: The 3rd AsiaEvo Conference
Topic: Open category
Presenter Name: Joy Bose


The discovery of antibiotics has substantial Implications and revolutionized global health in the 20th Century. The successful uses of antibiotics are not only limited to the treatment of bacterial, fungal, and parasitic infections but also to the treatment of chronic & life-threatening diseases such as cancer, diabetes, etc. Most importantly, antibiotics can be applied not only to treat humans rather to treat nearly all living entities on this earth. However, the other side of this successful story is indeed alarming. Precisely saying, extensive & unauthorized uses of antibiotics in human therapy, aquaculture, animal husbandry, and farming have imputed the emergence of antibiotic resistance in pathogens globally. Unfortunately, this scenario is not only limited to the uncontrolled use of antibiotics per se, raising demand for antibiotics resulting in substantial industrial production of diverse antibiotics, which in turn thrive mutation or horizontal gene transfer in pathogens to develop multiple mechanisms of resistance against each & every antibiotic used in practice. To date, various attempts have been made to develop strategies that encompass assessing molecular epidemiology, and biogeographical patterns, or introducing mathematical modeling to develop ‘evolution-proof antibiotic’. However, to complete the restoration of therapeutic applications of antibiotics, there is a need to understand, under antibiotic selection how pathogens enhance their fitness, which is often mediated by modulating virulence levels to exploit host resources efficiently. In this study, we have merely explored (a) antibiotic resistance evolution & its underlying costs and (b) virulence hitchhiking, as one of the prime consequences of antibiotic resistance using the experimental evolution approach. To perform experimental evolution, we exposed Bacillus thuringiensis (Bt); ID:18246; against streptomycin antibiotic over 30 serial transfers across 8 independent lines. Respective control lines were maintained in parallel without antibiotic throughout the serial transfers (i.e., two regimes: control & antibiotic selected). As expected, we did identify a direct response to selection in the presence of antibiotic in terms of bacterial growth dynamics and colony number at the expense of fitness trade-offs for the same traits in the absence of antibiotic. Interestingly, evolved Bt lines demonstrated elevated virulence by exacerbating host fitness against Caenorhabditis elegans & Drosophila melanogaster infections. Such elevated virulence of antibiotic-resistant in Bt lines across two distantly related phylum postulates a robust hitchhiking of virulence alleles that is contiguous to antibiotic resistance evolution. Taken together, our findings elucidate that in addition to epidemiological, molecular,  & theoretical approaches in drug development, the evolutionary underpinning of pathogens' fitness needs to be appraised on a serious note to reverse the frightening trend of antibiotic resistance.