Abstract
Background
Environmental monitoring of enterobacteria in hospital wastewater could be a useful tool to understand the composition of the microbiota in patients, their visits, and healthcare personnel, but it also may be useful for monitoring antimicrobial resistance among healthcare-associated infections in hospitalized patients. The aim of this study was to characterize and describe the phenotypic and genotypic antimicrobial resistance of Escherichia coli and Klebsiella sp. strains from wastewater and from clinical isolates in a tertiary care children’s hospital in Lima, Perú.
Methods
We systematically collected 70 isolates of Escherichia coli and Klebsiella sp. from wastewater and 24 isolates of the same enterobacteria from blood and urine cultures at Instituto Nacional de Salud del Niño San Borja (INSN-SB) in Lima from December 2018 to May 2019. Susceptibility profiles were evaluated following CLSI criteria. We used the Jarlier method for the detection of extended-spectrum beta-lactamases (ESBL). For detection of AmpC beta-lactamases, we used discs of cefoxitin, ceftazidime, and ceftriaxone combined with cloxacillin and cefotaxime. For the detection of carbapenemase production, we used EDTA and phenylboronic acid inhibitors between meropenem and imipenem disks. We performed genomic sequencing for the detection of resistance genes and to perform a phylogenetic cluster analysis.
Results
We collected a total of 94 isolates (70 from wastewater and 24 from clinical samples). Among the total isolates, 19 (20.2%) were ESBL producers. The frequency of ESBL producers in wastewater was 7.1% (5/24), whereas the frequency of ESBL producers in clinical samples was 58.3% (14/70). The most frequent resistance genes were tet (variant 34 and A) and blaTEM-1. The frequency of tet(34) and tet(A) were 10% and 7%, respectively, in isolates from wastewater, whereas the frequency of these genes were 0% and 6%, respectively, in clinical isolates. The gene blaCTX-M-15 was present in isolates from wastewater (1%) and clinical samples (2%). Phylogenetic cluster analysis found no similarities between isolates from wastewater and to those from clinical samples, suggesting that the population of these enterobacteria were different in wastewater compared with clinical samples.
Conclusions
Enterobacteria from hospital wastewater may not reflect the profile of infections caused by these microorganisms. However, they may reflect the microbiological microbiota among patients, their visits, and hospital healthcare personnel. Further studies that compare the phenotypic and genotypic characteristics among isolates from wastewater and the enteric microbiota from these individuals would be necessary to assess this hypothesis.
Author response: Assessing the danger of self-sustained HIV epidemics in heterosexuals by population based phylogenetic cluster analysis
