Banca de QUALIFICAÇÃO: YGOR DE OLIVEIRA PESSOA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : YGOR DE OLIVEIRA PESSOA
DATE: 26/11/2025
TIME: 08:30
LOCAL: Virtual GOOGLE MEET https://meet.google.com/hns-mvts- tkz
TITLE:

Resistência antimicrobiana em bactérias isoladas de ostras (Crassostrea gigas)comercializadas no litoral de  Natal/RN: uma abordagem sob o conceito One Health

 

KEY WORDS:

Antimicrobial resistance, Oysters, Escherichia coli, One Health, ESBL.

 

PAGES: 65
BIG AREA: Ciências Biológicas
AREA: Microbiologia
SUMMARY:

The aim of this study was to isolate and identify multidrug-resistant (MDR)
microorganisms from oysters collected on Genipabu beach (Natal/RN) and from oysters sold on Ponta
Negra and Forte beaches (Natal/RN). The oyster contents were macerated and cultured in peptone water
for 20 h at 37°C. Then, 10 µL were plated on MacConkey Agar (MCA) + Cefotaxime (8 μl/mL), AMC +
Meropenem (2 μl/mL), AMC + Colistin (8 μl/mL), M-Enterococcus Agar + Vancomycin (2 μl/mL), Salt
Mannitol Agar + Oxacillin (2 μl/mL) and CHROMagar Candida + Meropenem (2 μl/mL). After incubation for
24 h at 37°C, the grown colonies of different morphotypes were subcultured in antibiotic-containing
medium and subjected to antibiotic susceptibility testing by the disk diffusion method following the BrCast 2025 protocol. Bacter ia were identified by MALDI-TOF. A total of 329 microorganisms isolated from oysters collected both in the wild and from commercially available oysters were analyzed. Of these microorganisms, 34 were yeasts and 395 were bacteria. Among the bacteria, 28 presented a profile suggestive of MDR, identified as Escherichia coli, Klebsiella pneumoniae, and Citrobacter spp. These isolates were resistant to at least one antimicrobial agent belonging to three different antibiotic classes. The profiles found in MDR bacteria were characteristic of producers of ESBL (Extended Spectrum Beta-Lactamase), AmpC, Serine beta-lactamase, and Metallo beta-lactamase. These profiles were confirmed by the presence of a ghost zone in the combined disk test, phenylboronic acid (PB) disk test, and rapid test. The minimum inhibitory concentration (MIC) for colistin
was determined, highlighting a resistance profile. Furthermore, 21 bacteria identified as Enterococcus spp.
were found, of which 15 are resistant to glycopeptides such as vancomycin and teicoplanin. Furthermore,
antimicrobial susceptibility testing (AST) was performed on the 62 Pseudomonas spp. isolates, which
showed an intermediate sensitivity profile to the antibiotics tested. The MICs for fluconazole,
tebuconazole, and micafungin were determined for the yeast isolates found. Thus, this research shows the
worrying presence of resistant bacteria in oysters, especially those sold commercially, confirming that these
animals can serve as a reservoir for such bacteria and pose a risk to human health.

 

 

COMMITTEE MEMBERS:
Externo à Instituição - CAIO AUGUSTO MARTINS AIRES
Interna - 1049952 - DEYSIANE OLIVEIRA BRANDAO
Presidente - 1452833 - MARIA CELESTE NUNES DE MELO