OXA-244-Producing ST131 From Surface and Groundwaters of Pavia Urban Area (Po Plain, Northern Italy).

The study aimed to investigate (i) the occurrence of third-generation cephalosporins and/or carbapenems non-sensitive in Pavia surface and groundwaters, (ii) their resistance determinants, and (iii) the clonal features of the most relevant strains. During May 13 and 14, 2019, = 18 water samples from = 12 sampling sites in the urban/peri-urban area of Pavia (Po Plain, Northern Italy) have been evaluated. At first, hydrochemical analysis and bacterial plate counts were carried out on all the water samples. One milliliter of each water sample was then screened on both MacConkey agar (MC) added with cefotaxime (1 mg/L; 2 mg/L) and MC plus meropenem (0.25 mg/L; 4 mg/L). Species identification and antimicrobial susceptibilities were assessed by MicroScan autoSCAN-4. Double Disk Synergy (DD) test, CT103XL microarray, S, CTX-M-/MOX-/VEB-/OXA-type genes targeted PCR and sequencing, Pulsed-Field Gel Electrophoresis (PFGE), MultiLocus Sequence Typing (MLST), and Whole-Genome Sequencing on selected strains were performed. A total of = 30 isolates grown on β-lactams enriched MC: ( = 21; 70%), spp. ( = 5; 16.6%), ( = 2; 6.7%), and ( = 2; 6.7%). All and were ESβL-producers by DD. The 66.6, 38.0, and 19.0% of were ciprofloxacin/levofloxacin, trimethoprim-sulfamethoxazole, and gentamicin resistant (EUCAST 2019 breakpoints), respectively. A CTX-M-type determinant was identified in ( = 20/21; 95.2%) and ( = 2/3; 66.7%). The remaining was VEB-1 and MOX-2 genes positive. The (6' determinant was found in = 7 and = 1 , while was found in = 1 and = 2 . PFGE showed clonal heterogeneity among ESβL-. Two out of four detected as OXA-244-positive, belonged to the pandemic ST131. One XDR from a stream sample, detected as KPC-2 positive, resulted of ST258. The epidemiological impact of OXA-244 ST131 and KPC-2 ST258 presence in surface waters of an urban area in Northern Italy must not be underestimated.