Food wastes as a potential hotspot of antibiotic resistance: synergistic expression of multidrug resistance and ESBL genes confer antibiotic resistance to microbial communities

This study investigated antibiotic resistance (ABR) and extended-spectrum ss-lactamases (ESBL) patterns in bacterial isolates collected from the dairy, hotel, meat, and canteen food waste samples. A total of 144 bacterial strains were collected and screened for resistance against 9 standard antibiotics belonging to three generations and ESBL production. The ABR profile of the bacterial isolates was observed against all four major antibiotic groups (aminoglycosides, ss-lactams, quinolone, and others), where resistance against cefotaxime (> 70%) and methicillin (> 50%) was high. Though the ABR pattern of strains from dairy waste (> 50%) was high against first-generation antibiotics, the strains from meat waste (> 50%) showed considerable resistance against second- and third-generation antibiotics. ESBL-producing isolates were screened (> 60%, n = 144) through primary identification tests (combined disk test and double disk synergy tests) and further confirmed through Hexa G-minus 23 and 24 and MIC E-stripe following CLSI guidelines. Genes conferring ESBL resistance bla(CTX-M), bla(SHV), bla(OXA), bla(TEM), bla(KPC) genes and multidrug resistance (MDR) mexF gene were detected in the selected isolates with ABR and ESBL traits. Isolates with multidrug ABR and ESBL phenotype were further genotypically identified through 16 s rRNA gene sequencing. The synergy of ABR was detected through the co-expression of ESBL and MDR in isolates with a high occurrence of ABR and ESBL. The results demonstrate the significance of food waste as a natural reservoir of ABR and ESBL-producing pathogens, highlighting the importance of resistance monitoring and its interventions.