ABSTRACT
@#Antimicrobial resistance (AMR) is a global health crisis. Despite the drug discovery efforts, AMR is increasing, and discoveries are nearly nil. It is thus critical to design new strategies. Probiotics are tapped as alternatives to antibiotics for the treatment of gut-associated diseases. Lactobacillus species, common in food products, can inhibit the growth of gut pathogens. Here, we demonstrate the antimicrobial activities of Lactobacillus species – Lactobacillus paracasei, Lactobacillus casei, and Lactobacillus delbrueckii subsp. bulgaricus are enhanced when cocultured with Salmonella enterica subsp. enterica serovar Typhimurium. Cell-free culture supernatants (CFCS) from cocultures of Lactobacillus spp. and Salmonella enterica serovar Typhimurium more potently inhibit pathogen growth than their monoculture counterparts. Interestingly, we discovered that Salmonella enterica serovar Typhimurium could enhance the production of antimicrobials from Lactobacillus spp., most evident in L. delbrueckii subsp. bulgaricus. Also, L. delbrueckii subsp. bulgaricus CFCS upregulates key Salmonella virulence genes, hilA and sipA. Whether this increases Salmonella’s pathogenicity in vivo or reduces pathogen fitness and growth inhibition in vitro warrants further investigation. We propose that these probiotic isolates may be utilized for innovative natural food processing and preservation strategies to control Salmonella food contaminations. Importantly, our findings that Salmonella elicits an enhanced antimicrobial activity from Lactobacillus spp. provide evidence of a pathogen-mediated elicitation of antimicrobial production. Therefore, extending this phenomenon to other microbial interactions may help augment the strategies for drug discovery.
ABSTRACT
@#The poultry industry is a major contributor to the Philippine economy. Given the rising concerns in antibiotic resistance and food security, farmers need to maximize profit and output while ensuring safe and ecologically sustainable farming practices. This study surveyed antibiotic use in 12 commercial poultry farms in the Philippines. All farms reported the use of medically important antibiotics either for prophylaxis (91.67%), metaphylaxis (100%), and growth promotion (50%). Considering the widespread use of medically important antibiotics, we then investigated the potential contribution of local antibiotic treatment protocols to the emergence of antibiotic resistance genes in the fecal samples of broiler chickens under a controlled experimental setup. Significantly, we observed the emergence of antibiotic resistance genes (ermB) in fecal samples of antibiotic-treated broilers after 7 days and 21 days in antibiotic-free broilers raised in the same farming environment. These data were corroborated by antibiotic resistance gene profiles of fecal samples from commercial poultry farms. Antibiotic resistance genes (tetA, tetB, tetU, tetW, qnrB, qnrS) were prevalent in the fecal samples of antibiotic-treated broilers treated with tetracycline and quinolone antibiotics. Therefore, our study provides concrete evidence for the strong correlation between the use of medically important antibiotics in poultry farming and the emergence of antibiotic resistance genes. Antimicrobial resistance is a major contributor to failures in infectious disease treatment strategies in humans and animals. Therefore, the cost-benefit ratio of poorly regulated antibiotic treatment protocols in poultry farming could have a long-term detrimental impact on our economy and public health. Our study suggests the need to review our current policies and practices in using medically important antibiotics in the Philippine poultry industry.