Isolation and Molecular Identification of Multidrug-Resistant Aeromonas spp. from Hospital Wastewater in Mosul City

Hospital wastewater has the potential to concentrate antimicrobial resistant bacteria and resistance determinants, but there has been limited investigation of hospital laboratory wastewater as a targeted surveillance matrix. The aim of the present study was to isolate and identify Aeromonas spp. from hospital laboratory wastewater in Mosul City, Iraq by culture, VITEK 2, PCR targeting gyrB and antimicrobial susceptibility testing. Twenty-four wastewater grab samples were collected from fixed laboratory wastewater drainage points at Ibn Sina Hospital, Al-Salam Hospital and Mosul General Hospital over four consecutive weeks. At each weekly visit, one specimen was collected in the morning and another at approximately 5:00 PM from the same point; specimens were processed independently. Selected colonies were evaluated by VITEK 2, and 16 isolates assigned to Aeromonas/Aeromonas-like groups underwent gyrB-target PCR. Antimicrobial susceptibility testing was performed using VITEK 2; retained aggregate AST observations were available all of the agents. Seventeen of 24 samples yielded presumptive Aeromonas-like growth (70.8%; 95% CI, 50.8–85.1%). VITEK 2 assigned 16/18 selected colonies to Aeromonas/Aeromonas-like groups (88.9%; 95% CI, 67.2–96.9%), and 15/16 yielded the expected ~1,100-bp gyrB amplicon (93.8%; 95% CI, 71.7–98.9%). Among these 15 isolates, VITEK 2 operational assignments were A. caviae group (40.0%), A. hydrophila complex (26.7%), A. veronii (26.7%), and Aeromonas spp./sobria complex (6.7%). Aggregate I+R non-susceptibility was highest for tetracycline (60.0%), cefotaxime (53.3%), and ceftriaxone (46.7%); ceftazidime, ciprofloxacin, trimethoprim-sulfamethoxazole, and piperacillin-tazobactam were each 33.3%. Aeromonas/Aeromonas-like isolates with clinically relevant antimicrobial non-susceptibility were recovered from hospital laboratory wastewater in Mosul. VITEK 2 species/group assignments should be interpreted as operational rather than sequence-confirmed, and the findings support larger, longitudinal environmental AMR surveillance integrating sequence-based identification and isolate-level resistance characterization.