Autor(es): Freire, Samanta ; Grilo, Teresa ; Rodrigues, Bruna ; Oliveira, Rui ; Esteves, Carla ; Marques, António ; Poirel, Laurent ; Aires-de-Sousa, Marta
Data: 2023
Identificador Persistente: http://hdl.handle.net/10362/158536
Origem: Repositório Institucional da UNL
Assunto(s): bivalves; carbapenemases; ESBL; Escherichia coli; Klebsiella pneumoniae; Portugal; Microbiology; Microbiology (medical); Virology; SDG 3 - Good Health and Well-being; SDG 14 - Life Below Water
Funding Information: This work was partially financed by the Portuguese Red Cross, by the University of Fribourg, and by the Swiss National Science Foundation (projects FNS-31003A_163432 and FNS-407240_177381). Publisher Copyright: © 2023 by the authors.
Bivalves are filter-feeding organisms and biomarkers of bacterial pollution. Our study aimed to analyze the occurrence and characteristics of extended-spectrum β-lactamase (ESBL)- and carbapenemase-producing Escherichia coli among bivalves. A total of 522 bivalve samples were collected along Portuguese shellfish production areas. Homogenized samples were screened for E. coli contamination on corresponding selective plates, allowing for concomitant growth of Klebsiella pneumoniae. E. coli growth was observed in 39% of the samples. Subsequent selective screening identified nine samples (4.4%) contaminated with ESBL producers, corresponding to E. coli (n = 7) and K. pneumoniae (n = 2), while a single carbapenemase-producing K. pneumoniae (0.5%) was identified. ESBLs were all CTX-M-types commonly identified in human isolates, i.e., CTX-M-32 (n = 4), CTX-M-15 (n = 4), and CTX-M-14 (n = 1). The carbapenemase producer harbored the blaGES-5 gene located on a ColE plasmid. Clonality was evaluated by multilocus sequence typing, identifying E. coli backgrounds as ST10, ST23, ST540, ST617, ST746, SLV206, and SLV2325, commonly identified among environmental and human strains. The K. pneumoniae isolates belonged to ST834, ST15, and DLV644. The occurrence of ESBL- and carbapenemase-producing Enterobacteriaceae in bivalves reveals how the marine environment constitutes a reservoir of critical bacterial pathogens, thus potentially representing a risk to human health.
