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Projeto de investigação
Centre for the Research and Technology of Agro-Environmental and Biological Sciences
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Salmonella spp., Escherichia coli and Enterobacteriaceae Control at a Pig Abattoir: Are We Missing Lairage Time Effect, Pig Skin, and Internal Carcass Surface Contamination?
Publication . Dias Costa, Rui; Silva, Vanessa; Leite, Ana; Saraiva, Margarida; Teixeira Lopes, Teresa; Themudo, Patrícia; Campos, Joana; Vieira-Pinto, Madalena
To provide meat safety and consumer protection, appropriate hygiene control measures at an abattoir are required. This study aimed to evaluate the influence of visual fecal contamination level (VFCL) and lairage time (LT) on pig skin (PS) and external (ECS) and internal (ICS) carcass surfaces. The presence of Enterobacteriaceae, Escherichia coli (E. coli) and Salmonella in PS, ECS, and ICS were evaluated. A total of 300 paired samples were collected from 100 pigs. Results underlined the importance of the skin (Enterobacteriaceae: 3.27 ± 0.68 log CFU/cm2; E. coli: 3.15 ± 0.63 log CFU/cm2; Salmonella: 21% of samples) as a direct or indirect source of carcass contamination. Although VFCL revealed no significant effect (p > 0.05), the increase of LT had a significant impact (p < 0.001) on Enterobacteriaceae and E. coli levels across all analysed surfaces, and Salmonella presence on ICS (p < 0.01), demanding attention to LT. Also, the ICS showed a higher level of these bacteria compared to ECS. These results highlight the need of food business operators to consider ICS as an alternative area to sample for Salmonella, as a criterion for process hygiene based on EC Regulation No. 2073/2005, and as a potential contamination source to be integrated in the hazard analysis critical control point (HACCP) plans.
BlaGES-6 producing Pseudomonas aeruginosa ST235 is involved in resistance to different β-lactams
Publication . de Sousa, Telma; Machado, Sandro; Carvalho, Márcia; Caniça, Manuela; Ramos, Miguel J.N.; Santos, Daniela; Beyrouthy, Racha; Bonnet, Richard; Hébraud, Michel; Gomes, João Paulo; Igrejas, Gilberto; Poeta, Patrícia
Multidrug resistance in Pseudomonas aeruginosa, particularly resistance to carbapenem, represents a major challenge for public health. This study investigated resistance mechanisms in three P. aeruginosa isolates: HU63 (blaGES-6 carbapenemase-positive), HU141 (carbapenem-resistant without carbapenemase), and PAO1 (control). Genomic analysis revealed distinct sequence types (ST235 for HU63, ST253 for HU141) and chromosomal integration of resistance genes. HU63 harbored diverse resistance mechanisms, including β-lactamases (bla, bla, bla) and efflux pumps. Minimum inhibitory concentration assays demonstrated HU63's resistance to all β-lactams tested (meropenem, imipenem-cilastatin, ceftazidime, piperacillin-tazobactam), while HU141 remained susceptible except to cefoxitin and cloxacillin. Time-kill assays revealed tolerance phenotypes, with HU63 showing regrowth after 8-24 h despite initial reductions in bacterial density. Gene expression varied significantlydepending on the antibiotic and the isolate. The HU63 isolate (GES-6 positive) stands out for its marked induction of bla in all the antibiotics tested, contributing to its resistance to carbapenems and broad-spectrum cephalosporins. These expression profiles corroborate the classic molecular mechanisms of resistance: regulation of entry pores (oprD), activation of efflux pumps (mexA) and production of β-lactamases (bla, ampC) adapted to each situation. These findings underscore the multifactorial nature of resistance in Carbapenem-resistant Pseudomonas aeruginosa (CRPA), combining enzymatic inactivation, efflux, and genetic adaptability. The study emphasizes the urgent need for genomic surveillance to track high-risk clones and develop therapies targeting tolerance mechanisms alongside traditional resistance.
Assessment of Antibiotic Resistance Among Isolates of Klebsiella spp. and Raoultella spp. in Wildlife and Their Environment from Portugal: A Positive Epidemiologic Outcome
Publication . Sabença, Carolina; de la Rivière, Rani; Barros, Paulo; Cabral, João Alexandre; Sargo, Roberto; Sousa, Luís; Dapkevicius, Maria de Lurdes Enes; Silva, Filipe; Lopes, Filipa; Abrantes, Ana Carolina; Vieira-Pinto, Madalena; Caniça, Manuela; Igrejas, Gilberto; Torres, Carmen; Poeta, Patrícia
One of the significant challenges facing modern medicine is the rising rate of antibiotic resistance, which impacts public health, animal health, and environmental preservation. Evaluating antibiotic resistance in wildlife and their environments is crucial, as it offers essential insights into the dynamics of resistance patterns and promotes strategies for monitoring, prevention, and intervention. and genera isolates were recovered from fecal samples of wild animals and environmental samples using media without antibiotic supplementation. Antibiograms were performed for 15 antibiotics to determine the phenotypic resistance profile in these isolates. Extended-spectrum β-lactamase (ESBL) production was tested by the double-disc synergy test, and one ESBL-producing isolate was screened by PCR and whole-genome sequencing. Biofilm production was analyzed using the microtiter plate method. A total of 23 spp. and 3 spp. isolates were obtained from 312 fecal samples from wild animals, 9 spp. and 4 spp. isolates were obtained from 18 river and stream water samples, and 4 spp. and 3 spp. isolates from 48 soil samples. Regarding antibiotic resistance, only one isolate of from soil samples was an ESBL-producer and showed resistance to six antibiotics. This isolate harbored multiple β-lactams genes (, , , and ), as well as genes of resistance to quinolones, sulfonamides, tetracycline, aminoglycosides, and chloramphenicol, and belonged to the lineage ST307. Most of the spp. and spp. isolates were biofilm producers (except for one isolate), and 45.6% were weak biofilm producers, with the remaining being moderate to strong biofilm producers. We can conclude that antibiotic resistance is not widespread in these environment-associated isolates, which is a positive epidemiological outcome. However, identifying a single ESBL- isolate should serve as a warning of potential hotspots of resistance emergence.
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Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
6817 - DCRRNI ID
Número da atribuição
UIDB/04033/2020