The human oral cavity harbours diverse commensal and opportunistic bacteria that can act as reservoirs of antibiotic resistance. This study characterized the occurrence and antibiotic susceptibility of bacteria from 198 oral swab samples from consenting adults, using standard culture, Gram staining, biochemical identification, and Kirby-Bauer disc diffusion testing against ten antibiotics matched to each isolate's Gram reaction. Staphylococcus aureus was the most frequent isolate (42, 21.2%), followed by Escherichia coli (34, 17.2%), Streptococcus salivarius (23, 11.6%), Streptococcus mitis (15, 7.6%), Staphylococcus epidermidis and Neisseria oralis (13 each, 6.6%), and Neisseria mucosa and Klebsiella pneumoniae (11 each, 5.6%); 14.6% of samples showed no growth and 3.5% were undefined. Females yielded more isolates than males, but this was not statistically significant (χ² = 3.04, df = 9, p = 0.963). Resistance to amoxicillin and ampiclox (Gram-positive isolates) and to amoxicillin and sparfloxacin (Gram-negative isolates) was consistently high (13.0-81.8%), with K. pneumoniae showing the highest resistance (81.8% to amoxicillin). Chi-square testing showed organism identity significantly associated with resistance status in both the Gram-positive (χ² = 23.33, df = 3, p < 0.001) and Gram-negative groups (χ² = 42.67, df = 3, p < 0.001), driven mainly by the low resistance of both Neisseria species. Levofloxacin and ciprofloxacin (Gram-positive panel) and gentamycin and ofloxacin (Gram-negative panel) retained the greatest activity. These findings indicate that the oral cavity of healthy individuals harbours bacteria with considerable, organism-dependent resistance to commonly prescribed antibiotics, especially β-lactams, underscoring the need for antimicrobial stewardship and continued community-level resistance surveillance.

Diseases caused by waterborne and foodborne pathogenic bacteria present a significant threat to global health and economic stability. Although traditional culture-based methods have long been used, they suffer from time-consuming procedures, underestimation of viable counts, and the inability to detect viable but non-culturable (VBNC) cells. Therefore, this research provides a comprehensive applied study of advanced molecular techniques as precise and rapid diagnostic tools. The study highlights the effectiveness of Polymerase Chain Reaction (PCR) variants and Gene Sequencing techniques in detecting and characterizing enteric and non-enteric pathogenic bacteria (such as E. coli O157:H7, Campylobacter, Salmonella, Shigella, and Legionella) in wastewater environments and wastewater-based epidemiology (WBE). The findings show that molecular methods offer high sensitivity and specificity, effectively overcoming matrix inhibitors and serving as a crucial foundation for early warning and outbreak control.