Antibiotic-resistant Aeromonas spp. are increasingly detected in aquatic environments and may represent a potential public health concern, particularly due to resistance to β-lactam and carbapenem antibiotics. This study aimed to genomically characterize antibiotic-resistant Aeromonas strains isolated from treated urban wastewater and assess their resistance and virulence potential. Four Aeromonas strains were isolated from treated urban wastewater and subjected to whole-genome sequencing and phenotypic antibiotic susceptibility testing. Sequence analysis identified the strains as Aeromonas hydrophila (strain C01), A. veronii (strain C02), and A. caviae (strains C09 and C10). All strains were resistant to ampicillin and cefotaxime, whereas C01 and C02 were resistant to imipenem, while C09 and C10 remained susceptible. Genomic analysis revealed distinct β-lactamase repertoires, with strains C01 and C02 harboring OXA- and CphA-type genes, whereas strains C09 and C10 carried OXA- and MOX-type β-lactamases. The presence of CphA-family β-lactamases in C01 and C02 was consistent with their high imipenem MICs. Multiple virulence-associated genes were detected, including secretion systems and toxins. The type II secretion system (T2SS) was identified in all isolates, whereas type III secretion system (T3SS)-associated genes were detected in A. veronii C02 and type VI secretion system (T6SS)-associated genes in A. hydrophila C01. Moreover, hemolysin A was found in all strains, whereas hemolysin III was only detected in A. hydrophila C01 and A. veronii strain C02. The detection of antibiotic-resistant Aeromonas strains carrying multiple virulence-associated genes in treated wastewater highlights the importance of wastewater effluent surveillance to better understand their occurrence and potential environmental dissemination.
Antibiotic-resistant Aeromonas spp. are increasingly detected in aquatic environments and may represent a potential public health concern, particularly due to resistance to β-lactam and carbapenem antibiotics. This study aimed to genomically characterize antibiotic-resistant Aeromonas strains isolated from treated urban wastewater and assess their resistance and virulence potential. Four Aeromonas strains were isolated from treated urban wastewater and subjected to whole-genome sequencing and phenotypic antibiotic susceptibility testing. Sequence analysis identified the strains as Aeromonas hydrophila (strain C01), A. veronii (strain C02), and A. caviae (strains C09 and C10). All strains were resistant to ampicillin and cefotaxime, whereas C01 and C02 were resistant to imipenem, while C09 and C10 remained susceptible. Genomic analysis revealed distinct β-lactamase repertoires, with strains C01 and C02 harboring OXA- and CphA-type genes, whereas strains C09 and C10 carried OXA- and MOX-type β-lactamases. The presence of CphA-family β-lactamases in C01 and C02 was consistent with their high imipenem MICs. Multiple virulence-associated genes were detected, including secretion systems and toxins. The type II secretion system (T2SS) was identified in all isolates, whereas type III secretion system (T3SS)-associated genes were detected in A. veronii C02 and type VI secretion system (T6SS)-associated genes in A. hydrophila C01. Moreover, hemolysin A was found in all strains, whereas hemolysin III was only detected in A. hydrophila C01 and A. veronii strain C02. The detection of antibiotic-resistant Aeromonas strains carrying multiple virulence-associated genes in treated wastewater highlights the importance of wastewater effluent surveillance to better understand their occurrence and potential environmental dissemination.
