Industrial effluents are reservoirs for multidrug-resistant (MDR) bacteria due to co-selection pressure from heavy metals and residual antibiotics. This study assessed the prevalence of heavy metal- and antibiotic-resistant bacteria in wastewater from four industrial sectors in the Hayatabad Industrial Zone, Peshawar, Pakistan. A total of 23 bacterial isolates were obtained from 16 composite samples; while this sample size is appropriate for an initial characterization in this understudied region, it highlights the need for expanded surveillance. Isolates included Pseudomonas aeruginosa , Bacillus cereus , Staphylococcus aureus , and Escherichia coli . These strains showed notable tolerance to chromium (MIC up to 100 µg/mL), cadmium (MIC up to 64 µg/mL), and zinc (MIC up to 64 µg/mL). Antibiotic susceptibility testing revealed a strong phenotypic link between metal tolerance and MDR profiles. Notably, a high proportion of isolates exhibited reduced susceptibility to last-resort antibiotics: P. aeruginosa and E. coli showed resistance to colistin (39.13% and 34.7%, respectively), while S. aureus exhibited reduced susceptibility to vancomycin (43.47%, MIC ≥ 16 µg/mL). Pearson correlation analysis, performed using SPSS v.28 after confirming data normality via Shapiro-Wilk tests, revealed significant positive correlations between metal MICs and antibiotic resistance rates, particularly for gentamicin ( r = 0.81, p = 0.003), colistin ( r = 0.79, p = 0.004), and vancomycin ( r = 0.77, p = 0.005). 16 S rRNA sequencing confirmed isolate identities with > 99% homology to reference strains. The results highlight industrial wastewater as a potential source of resistance gene dissemination. These findings emphasize the urgent need for improved wastewater treatment, regulatory controls, and continuous environmental monitoring to combat the spread of MDR pathogens.
Khan et al. (Thu,) studied this question.