Resistance against last resort antibiotics in Klebsiella spp. isolated from community and hospital raw sewage in Buenos Aires, Argentina

GHIGLIONE BÁRBARA; HAIM MARÍA SOL; ESCOBAR RIVERA ADRIANA; FIGUEROA ESPINOSA ROQUE A; GUTKIND GABRIEL; POWER PABLO; DI CONZA JOSÉ; DROPA MILENA

Copenhagen

Congreso; 33rd European Congress of Clinical Microbiology and Infectious Diseases; 2023

ESCMID

BackgroundIn Argentina, antibiotic resistance monitoring in pathogens is mostly carried out in theclinical setting as part of surveillance programs based on isolates of human origin. Wedesigned a pilot project to investigate Gram-negative bacilli isolated from wastewater inBuenos Aires, to set a framework for wastewater-based surveillance (WBS).MethodsComposite samples were collected in sterile bottles from the sewer of a pediatric clinic (PC),a general hospital (GH), and the influent line of a wastewater treatment plant (WWTP), inDecember 2018, July 2019 and March 2020. Each 1-L sample was filtered (0.45 μM), andDNA was extracted from membranes using a commercial kit, while one membrane from eachlocation was cultivated in MacConkey agar. A suspension was made in saline solution and100 μl were inoculated in MacConkey broth supplied with different antibiotics. Brothcultures were inoculated on MacConkey agar plates, and distinctive colonies were subcultivatedin TSA and identified by MALDI-TOF/MS. Klebsiella spp. isolates were selectedfor further characterization by mCIM, disk diffusion against nine antibiotics andCAST/eCAST test. Detection of carbapenemases and ESBL genes was performed by PCR,while diversity was assessed by REP and ERIC-PCR methods.ResultsA total of 402 isolates were recovered, from which 144 were Klebsiella spp., and 76 werecarbapenemase producers according to mCIM, 59% from the WWTP, 27% from the GH and13% from PC. Carbapenemase-encoding genes blaKPC, blaOXA and blaNDM were identifiedboth in WWTP and GH, with some of the isolates co-expressing KPC and OXA, but onlyblaNDM was detected in PC isolates. 24% of the isolates were resistant to colistin. 26%carried blaCTX-M and only one carried blaPER-2. Genes detected in total membrane DNAincluded blaCTX-M, blaOXA-48, blaVIM, blaNDM, blaPER-2, blaGES, blaCMY, blaKPC , mcr-1and mcr-3. REP and ERIC-PCR band patterns showed multiplicity of clones. Most isolatesshowed a multiresistant profile comprising cephalosporins, carbapenems, TMS andciprofloxacin, with varied resistance against gentamicin or amikacin.ConclusionsThis study shows the circulation of multidrug resistant Klebsiella spp. through water andestablishes the foundations to use this species as a possible bioindicator for WBS, apromising tool for studying diversity and antibiotic resistance.