To investigate the occurrence of carbapenem-resistant Klebsiella pneumoniae (CRKP) and their clonal relationships from hospital and municipal wastewater treatment plants (WWTPs). Eighteen K. pneumoniae strains recovered from three WWTPs were identified by MALDI-TOF. The antimicrobial susceptibility were evaluated by disk-diffusion and the carbapenemases production by Carbapenembac®. The carbapenemases genes were investigated by real-time PCR and the clonal relationship through multi-locus sequence typing (MLST). Thirty nine percent (7/18) of isolates were classified as multidrug-resistant (MDR), 61.1% (11/18) extensively drug-resistant (XDR) and 83.3% (15/18) showed carbapenemase activity. Three carbapenemase-encoding genes were found, bla_KPC (55%), bla_NDM (27.8%) and bla_OXA-370 (11.1%) as well five sequencing types ST11, ST37, ST147, ST244 and ST281. ST11 and ST244, sharing four alleles were grouped into clonal complex 11 (CC11). Our results show the importance of monitoring antimicrobial resistance in WWTPs effluents to minimize the risk of spreading bacterial load and ARGs in aquatic ecosystems, using advanced treatment technologies to reduce these emerging pollutants at WWTPs.

The emergence of vancomycin-resistant Enterococcus faecium (Efm) harboring vanA gene and multidrug-resistant determinants is a relevant public health concern. It is an opportunistic pathogen responsible for nosocomial infections widely distributed in the environment, including wastewater treatment plants (WWTPs). Our study addresses a genomic investigation of vanA -carrying Efm from WWTPs in Brazil. Samples from five WWTPs supplied with sewage from different sources were evaluated. Here we present whole-genome sequencing of eight vanA -Efm isolates performed on Illumina MiSeq platform. All these isolates presented multidrug-resistant profile, and five strains were from treated wastewater. Multiple antimicrobial resistance genes (ARGs) were found, such as aph(3′)-IIIa , ant(6′)-Ia , erm(B) , and msrC , some of them being allocated in plasmids. The virulence profile was predominantly constituted by efaAfm and acm genes and all isolates, except for one, were predicted as human pathogens. Multilocus sequence typing analysis revealed a new allele and five different STs, three previously described (ST32, ST168, and ST253) and two novel ones (ST1893 and ST1894). Six strains belonged to CC17, often associated with hospital outbreaks. As far as our knowledge, no genomic studies of vanA -Efm recovered from WWTPs revealed isolates belonging to CC17 in Brazil. Therefore, our findings point to the environmental spread of Efm carrying multiple ARGs.

Bivalve mollusks face a crisis due to infectious diseases, resulting in high mortality and economic losses. The need for continuous monitoring to prevent contamination from sewage and rainwater in aquaculture is evident. The recent mass mortality of scallops in Ilha Grande Bay (IGB), Rio de Janeiro’s largest scallop producer, due to environmental contaminants underscores the need for further research. This study aims to investigate the recent collapse of the scallop population and assess the human impact by analyzing the circulation of pathogens. Materials and Methods: Mollusks were collected from three sites in Ilha Grande Bay (IGB), a region known for its significant scallop production, and from scallop farms in Angra dos Reis, RJ. A total of 216 gill and adductor tissue samples from lion’s foot scallops were analyzed. Bacterial contamination was identified using MALDI-TOF, while antimicrobial susceptibility and carbapenem production were assessed via disk diffusion tests. Results: Mollusks were contaminated with V. alginolyticus, V. fluvialis, V. harveyi, Pseudomonas putida, and Pseudomonas monteilii. All isolates were sensitive to meropenem, but P. putida showed higher resistance to ciprofloxacin. Conclusions: The presence of these pathogenic and resistant bacteria in scallop adductor tissues is a concern for the aquaculture industry and a significant public health risk. The potential for these bacteria to enter the human food chain through consuming contaminated seafood or recreational activities such as bathing is a serious issue that needs to be addressed.

The increasing prevalence and dissemination of multidrug-resistant bacteria represent a serious concern for public health. Aeromonas caviae is a pathogenic microorganism that causes a wide spectrum of diseases in fish and humans and is often associated with aquatic environments and isolated from foods and animals. Here, we present the isolation and characterization of the V15^T strain isolated from a drinking water storage tank in Rio de Janeiro, Brazil. The V15^T strain has a genome length of 4,443,347 bp with an average G + C content of 61.78% and a total of 4028 open reading frames. Its genome harbors eight types of antibiotic resistance genes (ARGs) involving resistance to beta-lactamases, macrolides, and quinolones. The presence of bla_MOX-6, bla_OXA-427/bla_OXA-504, and mutations in parC were detected. In addition, other ARGs (macA, macB, opmH, and qnrA) and multidrug efflux pumps (such as MdtL), along with several resistance determinants and 106 genes encoding virulence factors, including adherence (polar and lateral flagella), secretion (T2SS, T6SS), toxin (hlyA), and stress adaptation (katG) systems, were observed. The genome sequence reported here provides insights into antibiotic resistance, biofilm formation, evolution, and virulence in Aeromonas strains, highlighting the need for more public health attention and the further monitoring of drinking water systems. Also, the results of physiological and phylogenetic data, average nucleotide identity (ANI) calculation, and digital DNA–DNA hybridization (dDDH) analysis support the inclusion of the strain V15^T in the genus Aeromonas as a new subspecies with the proposed name Aeromonas caviae subsp. aquatica subsp. nov. (V15^T = P53320^T). This study highlights the genomic plasticity and pathogenic potential of Aeromonas within household drinking water systems, calling for the revision of water treatment protocols to address biofilm-mediated resistance and the implementation of routine genomic surveillance to mitigate public health risks.

Background/Objectives: Klebsiella spp., particularly K. pneumoniae, are major opportunistic pathogens in healthcare settings driven by carbapenemase- and ESBL-producing strains. We assessed antimicrobial resistance and biofilm formation abilities in Klebsiella spp. from a Brazilian tertiary hospital and related environments and characterized capsular types. Methods: Over six months (July–December 2023), 303 carbapenem-resistant Klebsiella spp. were collected from clinical specimens (n = 198), ICU/non-ICU surfaces (n = 79), hospital sewage (n = 22), and stream water (n = 4). Species were identified by MALDI-TOF. Susceptibility testing covered eight antibiotic classes, focusing on carbapenems and polymyxin B. Biofilm formation was quantified by crystal violet, and capsular typing used wzi/K-locus approaches. Results: Most isolates (70.95%) had meropenem MICs ≥ 128 μg/mL, while 77.6% (n = 235) remained susceptible to polymyxin B. Resistance profiles largely consisted of extensive drug resistance (95.4%), with 1.3% exhibiting pandrug resistance, including isolates from bed rails. Biofilm formation was detected in 96.7% of isolates, mainly weak (67.6%) or moderate (28%), with 4.4% being strong producers. Among the Klebsiella isolates analyzed, 21 K types were identified with an uneven distribution dominated by K64, followed by K24, K173, and K50. K75 was the only K type detected across all sources—clinical isolates, bed-rail surfaces (non-ICU), wastewater, and fluvial water. Conclusions: Carbapenem-resistant Klebsiella spp. exhibited widespread resistance, with residual susceptibility to aminoglycosides, ceftazidime–avibactam, and polymyxins. Environmental reservoirs—hospital surfaces, sewage, and stream water—harbored resistant biofilm producers, reinforcing their role in persistence and dissemination. K-typing revealed concentrated distribution (predominantly K64) and cross-source K75. These findings underscore the urgency of integrated strategies combining molecular surveillance, antimicrobial stewardship, and environmental control.