Tertiary hospital sewage as reservoir of bacteria expressing MDR phenotype in Brazil

Incidence and Virulence Factor Profiling of Vibrio Species: A Study on Hospital and Community Wastewater Effluents

This study aimed to determine the incidence and virulence factor profiling of Vibrio species from hospital wastewater (HWW) and community wastewater effluents. Wastewater samples from selected sites were collected, processed, and analysed presumptively by the culture dependent methods and molecular techniques. A total of 270 isolates were confirmed as Vibrio genus delineating into V. cholerae (27%), V. parahaemolyticus (9.1%), V. vulnificus (4.1%), and V. fluvialis (3%). The remainder (>50%) may account for other Vibrio species not identified in the study. The four Vibrio species were isolated from secondary hospital wastewater effluent (SHWE), while V. cholerae was the sole specie isolated from Limbede community wastewater effluent (LCWE) and none of the four Vibrio species was recovered from tertiary hospital wastewater effluent (THWE). However, several virulence genes were identified among V. cholerae isolates from SHWE: ToxR (88%), hylA (81%), tcpA (64%), VPI (58%), ctx (44%), and ompU (34%). Virulence genes factors among V. cholerae isolates from LCWE were: ToxR (78%), ctx (67%), tcpA (44%), and hylA (44%). Two different genes (vfh and hupO) were identified in all confirmed V. fluvialis isolates. Among V. vulnificus, vcgA (50%) and vcgB (67%) were detected. In V. parahaemolyticus, tdh (56%) and tlh (100%) were also identified. This finding reveals that the studied aquatic niches pose serious potential health risk with Vibrio species harbouring virulence signatures. The distribution of virulence genes is valuable for ecological site quality, as well as epidemiological marker in the control and management of diseases caused by Vibrio species. Regular monitoring of HWW and communal wastewater effluent would allow relevant establishments to forecast, detect, and mitigate any public health threats in advance.

Antibiotic resistance profile of wastewater treatment plants in Brazil reveals different patterns of resistance and multi resistant bacteria in final effluents

Wastewater treatment plants (WWTPs) are recognized as important sources of Antibiotic Resistant Bacteria (ARBs) and Antibiotic Resistant Genes (ARGs), and might play a role in the removal and dissemination of antimicrobial resistance (AMR) in the environment. Detailed information about AMR removal by the different treatment technologies commonly applied in urban WWTPs is needed. This study investigated the occurrence, removal and characterization of ARBs in WWTPs employing different technologies: WWTP-A (conventional activated sludge-CAS), WWTP-B (UASB reactor followed by biological trickling filter) and WWTP-C (modified activated sludge followed by UV disinfection-MAS/UV). Samples of raw sewage (RI) and treated effluent (TE) were collected and, through the cultivation-based method using 11 antibiotics, the antibiotic resistance profiles were characterized in a one-year period. MAS was effective in reducing ARB counts (2 to 3 log units), compared to CAS (1 log unit) and UASB/BTF (0.5 log unit). The composition of cultivable ARB differed between RI and TE samples. Escherichia was predominant in RI (56/118); whilst in TE Escherichia (31/118) was followed by Bacillus (22/118), Shigella (14/118) and Enterococcus (14/118). Most of the isolates identified (370/394) harboured at least two ARGs and in over 80 % of the isolates, 4 or more ARG (int1, blaTEM, TetA, sul1 and qnrB) were detected. A reduction in the resistance prevalence was observed in effluents after CAS and MAS processes; whilst a slight increase was observed in treated effluents from UASB/BTF and after UV disinfection stage. The multi-drug resistance (MDR) phenotype was attributed to 84.3 % of the isolates from RI (27/32) and 63.6 % from TE (21/33) samples and 52.3 % of the isolates (34/65) were resistant to carbapenems (imipenem, meropenem, ertapenem). The results indicate that treated effluents are still a source for MDR bacteria and ARGs dissemination to aquatic environments. The importance of biological sewage treatment was reinforced by the significant reductions in ARB counts observed. However, implementation of additional treatments is needed to mitigate MDR bacteria release into the environment.

A set of antibiotic-resistance mechanisms and virulence factors in GES-16-producing Klebsiella quasipneumoniae subsp. similipneumoniae from hospital wastewater revealed by whole-genome sequencing

Klebsiella quasipneumoniae subsp. similipneumoniae has emerged as a human pathogen and sporadic isolates from non-clinical sources were reported. Here, we described the phenotypic- and genomic-characteristics of a multidrug-resistant (MDR) and potentially hypervirulent (MDR-hv) Klebsiella quasipneumoniae subsp. similipneumoniae (KqA1) isolated from hospital wastewater. The antibiotic susceptibility profile of KqA1 was investigated using disk-diffusion method, broth microdilution method, and agar dilution method, and the genetic characteristics of antimicrobial resistance, mobile genetics elements, and virulence were evaluated by genomic DNA sequencing on the Illumina® NovaSeq6000 platform as well as by bioinformatic analysis. Resistome analyses revealed the presence of genes related to resistance to β-lactams, aminoglycosides, quinolones, tetracyclines, sulfonamides, trimethoprim, chloramphenicol, macrolides, and fosfomycin. New genetic contexts to bla_GES-16 (carbapenemase gene) and to fosA (fosfomycin resistance gene) were described. A set of mechanisms that can contribute to antibiotic resistance, commonly detected in Klebsiella spp., was also found including chromosomal mutations, efflux systems, proteins, and regulators. Moreover, KqA1 presented genes related to tolerance to metals (arsenic, copper, nickel, cobalt, magnesium, cadmium, zinc, tellurium, selenium) and to biocides (quaternary-ammonium compounds). The isolate was classified as potentially hypervirulent due to a wide range of virulence factors found associated to regulation, motility, biofilm, effector delivery systems, immune modulation, nutritional/metabolic factors, adherence, invasion, and competitive advantage. The occurrence of MDR-hv KqA1 in hospital wastewater points out how this environment matrix plays a crucial role in the maintenance and selection of critical bacterial pathogens. Regarding One Health perspective, it is evident the need for multidisciplinary implementation of control measures for antibiotic-resistant bacteria, not only in hospital settings but also in a general environmental context to mitigate the dissemination of MDR and hv bacteria.

Sewage from a secondary hospital in Ribeirão Preto, southeastern Brazil: a source of multidrug-resistant Enterobacteriaceae

Antimicrobial resistance is one of the severe threats to global health. Hospital sewage can serve as a reservoir for multi-resistant bacteria and promote the spread of antimicrobial resistance. This study aimed to investigate the antimicrobial susceptibility and the pathogenic potential of Enterobacteriaceae isolated from the sewage of a secondary hospital in Ribeirão Preto, a city in southeastern Brazil. The strains were isolated by membrane filtration and identified by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF). The antimicrobial susceptibility profile was performed by disk diffusion. Polymerase chain reaction (PCR) assays were used to detect virulence genes among the strains. Twenty-eight isolates were obtained, with Klebsiella pneumoniae being the predominant species (71.4%, n = 20). All isolates were classified as multidrug-resistant, including four isolates that were non-susceptible to at least 50% of the tested antibiotics. All isolates were also non-susceptible to cefuroxime and sulfonamides antibiotics; however, they were susceptible to norfloxacin, ofloxacin, amikacin, gentamicin, netilmicin, ertapenem, cefazolin, cefaclor, and cefotetan. The virulence genes ycfM, fimH, mrkD, kfu, and entB were detected in several isolates. Our study showed that even in a secondary hospital, without the routine of major surgeries and intensive care admissions, the hospital sewage can harbor a high percentage of multidrug-resistant bacteria with pathogenic potential. This leads to the worrying risk of public health and environmental contamination.

Hospital liquid waste contaminated with multidrug-resistant bacteria raises a public health hazard alert in Brazil

The spread of multidrug-resistant bacteria (MDR) is a global concern because it poses a serious threat to public health. The inadequate handling of Health Services Waste (HSW) and, therefore, the incorrect disposal of infected liquids can cause contamination of the environment, the emergence of diseases caused by MDR bacteria, and the loss of the population's quality of life. The present study aimed to survey the bacteria and their antimicrobial resistance profiles, present in the liquid residues from infected surgeries performed in five years, often discharged into the sewage network of a large tertiary hospital located in the city of Uberlândia, which is considered one of the main economic and demographic centers of Brazil. A systematic and retrospective survey of the medical records of patients who underwent infected surgeries from January 2015 to December 2019 was carried out at the referred hospital. The bacterial species were previously identified and characterized for the antimicrobial susceptibility profile by the VITEK 2 automated system (bioMérieux, Brazil). In the evaluated period, 1658 infected surgeries were performed and the results showed 661 bacterial strains distributed in 48 different species, being Staphylococcus aureus the most prevalent species. The vast majority (85.6%) showed some type of antimicrobial resistance among these strains, with more than half (54.6%) being MDR. The results of this work raise an alert and concern for the risks to the environment and public health by dumping these infected liquid wastes directly into the sewage system without proper prior decontamination.