| Congresso Brasileiro de Microbiologia 2023 | Resumo: 575-2 | ||||
Resumo:Multidrug-resistant Enterobacterales, which were previously prevalent in the hospital environment, are increasingly being identified in nature, especially in water bodies, which
serve as large reservoirs of multiple antimicrobial resistance genes. Oysters, as filter-feeding
animals of the organic matter present in the water column, are susceptible to contact with
microorganisms, functioning as bioindicators of water quality. In this way, the objective of
this work was to conduct microbiological surveillance in aquatic environments, using oysters
as bioindicators of water quality. With the aim of investigating a possible source of
contamination by antimicrobial-resistant Enterobacterales, 1L sample of cultivation water
was collected, as well as, 100g of oysters in the larval stage, from the Marine Molluscs
Laboratory of Federal University of Santa Catarina, which is responsible for distributing
these oyster seeds to all producers in this study. Furthermore, samples of 15 adult oysters,
and 1L of the cultivation water were collected from oyster farmers located in the north bay
(n=3) and south bay (n=3) of Florianópolis/SC. Oysters from each production site were
dissected into the digestive gland and the rest of the animal's body, in an attempt to
differentiate a possible natural oyster microbiota from external contaminations. The
dissected parts were then homogenized and then incubated in tryptic soy enrichment broth
(TSB), at 37°C under agitation for 6 hours. The seawater was filtered through membranes
with 0.45μm pores, which were then incubated under the same conditions described above.
From each enrichment, aliquots were then transferred to a new TSB medium supplemented
with cefotaxime (CTX) (2µg/mL), ertapenem (ERT) (0.5µg/mL), gentamicin (CN) (2µg/mL)
and ciprofloxacin (CIP) (0.5µg/mL) separately, and incubated at 37°C overnight. After that,
samples were seeded in MacConkey agar, containing an antimicrobial disk equal to that
used in the selective pressure (CTX 30µg; ERT 10µg; CN 10µg and CIP 5µg) and incubated
at 37°C for 24h. Each morphologically distinct colony, which grew close to the antimicrobial
disk, was isolated and identified by MALDI-TOF. Antimicrobial susceptibility test was
performed using the disk diffusion method, as recommended by BrCAST for
Enterobacterales. For detection of Extended Spectrum Beta-Lactamases (ESBL), the
combined disk method was used, and the isolate was considered multidrug-resistant when it
showed resistance to at least three different categories of tested antimicrobials (β-lactams,
aminoglycosides, quinolones, tetracyclines). In total, 50 Enterobacterales with antimicrobial
resistance profiles were isolated. In samples of oyster seeds and their respective cultivation
water, no antimicrobial-resistant Enterobacterales was isolated, suggesting that the
contamination does not come from an origin root. Of the 50 isolates, 14 were isolated from
digestive gland, 13 from the rest of the oyster's body, and 23 were isolated from cultivation
water samples. Among the Enterobacterales isolated from oysters, 56% showed an ESBL
phenotype and 63% were multidrug-resistant, while in water samples 57% were ESBL and
61% were multidrug-resistant. The number of Enterobacterales isolated from oyster andwater samples, as well as the prevalence of ESBL and multidrug-resistant isolates, showed
great similarity, indicating that the contamination present in the water column accumulates in
the animals. Palavras-chave: Antimicrobial Resistance, Bioindicator, Enterobacteriales, One health, Oyster Agência de fomento:Fundação de Amparo à Pesquisa e Inovação do Estado de Santa Catarina (FAPESC); Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) | |||||