The Brazilian poultry industry generates large amounts of organic waste, such as chicken litter, which is often used in agriculture. Among the bacteria present in organic fertilizer are members of the Enterobacteriaceae family. The objective of this study was to detect the presence of diarrheagenic Escherichia coli (DEC) strains in avian organic fertilizer, and assess the potential damage they can cause in humans due to antimicrobial resistance. The presence of DEC pathotypes and phylogenetic groups were detected by multiplex-PCR. Phenotypic assays, such as tests for adhesion, cytotoxicity activity, biofilm formation and especially antimicrobial susceptibility, were performed. Fifteen DEC strains from 64 E. coli were isolated. Among these, four strains were classified as enteropathogenic (EPEC; 6.2%), three strains as Shiga toxin-producing (STEC; 4.7%), 10 strains as enteroaggregative (EAEC; 12.5%), but two of these harbored the eaeA gene too. The low number of isolated strains was most likely due to the composting process, which reduces the number of microorganisms. These strains were able to adhere to HEp-2 and HeLa cells and produce Shiga-toxins and biofilms; in addition, some of the strains showed antimicrobial resistance, which indicates a risk of the transfer of resistance genes to human E. coli. These results showed that DEC strains isolated from avian organic fertilizers can cause human infections.

Escherichia coli is a key indicator of food hygiene, and its monitoring in meat samples points to the potential presence of antimicrobial-resistant strains capable of causing infections in humans, encompassing resistance profiles categorized as serious threats by the Centers for Disease Control and Prevention (CDC), such as Extended-Spectrum Beta-Lactamase (ESBL)—a problem with consequences for animal, human, and environmental health. The objective of the present work was to isolate and characterize ESBL-producing E. coli strains from poultry, pork, and beef meat samples, with a characterization of their virulence and antimicrobial resistance profiles. A total of 450 meat samples (150 chicken, 150 beef, and 150 pork) were obtained from supermarkets and subsequently cultured in medium supplemented with cefotaxime. The isolated colonies were characterized biochemically, followed by antibiogram testing using the disk diffusion technique. Further classification involved biofilm formation and the presence of antimicrobial resistance genes (bla_CTX-M, AmpC-type, mcr-1, and fosA3), and virulence genes (eaeA, st, bfpA, lt, stx1, stx2, aggR, iss, ompT, hlyF, iutA, iroN, fyuA, cvaC, and hylA). Statistical analysis was performed via the likelihood-ratio test. In total, 168 strains were obtained, with 73% originating from chicken, 22% from pork, and 17% from beef samples. Notably, strains exhibited greater resistance to tetracycline (51%), ciprofloxacin (46%), and fosfomycin (38%), apart from β-lactams. The detection of antimicrobial resistance in food-isolated strains is noteworthy, underscoring the significance of antimicrobial resistance as a global concern. More than 90% of the strains were biofilm producers, and strains carrying many ExPEC genes were more likely to be biofilm formers (OR 2.42), which increases the problem since the microorganisms have a greater chance of environment persistence and genetic exchange. Regarding molecular characterization, bovine samples showed a higher prevalence of bla_CTX-M-1 (OR 6.52), while chicken strains were more likely to carry the fosA3 gene (OR 2.43, CI 1.17–5.05) and presented between 6 to 8 ExPEC genes (OR 2.5, CI 1.33–5.01) compared to other meat samples. Concerning diarrheagenic E. coli genes, two strains harbored eae. It is important to highlight these strains, as they exhibited both biofilm-forming capacities and multidrug resistance (MDR), potentially enabling colonization in diverse environments and causing infections. In conclusion, this study underscores the presence of β-lactamase-producing E. coli strains, mainly in poultry samples, compared to beef and pork samples. Furthermore, all meat sample strains exhibited many virulence-associated extraintestinal genes, with some strains harboring diarrheagenic E. coli (DEC) genes.

A microbiologia é a ciência que estuda os microrganismos e a relação destes com a nossa vida e meio ambiente. Entretanto, a microbiologia é um tema transmitido ao ensino médio, quase que exclusivamente de forma conceitual e teórica pelo professor, exigindo para sua compreensão, um alto ní­vel de abstração por parte do aluno, dificultando o processo de aprendizagem. O presente trabalho teve como objetivo aplicar a metodologia do PBL no ensino de microbiologia para o ensino médio, relacionando-a com o cotidiano dos estudantes. O PBL coloca o aluno como papel central na produção do conhecimento, visto que o mesmo deve procurar soluções para um problema que lhe é apresentado. O trabalho realizado fez parte do projeto de extensão "Reconhecendo a microbiologia no nosso dia a dia" , financiado pela Secretaria da Ciência, Tecnologia e Ensino Superior do Estado do Paraná (SETI-PR). Neste projeto atuaram docentes e discentes de pós-graduação (mestrado e doutorado) e graduação, abrangendo cursos de diferentes áreas (Artes visuais, Biologia, Biomedicina, Farmácia, entre outros). Foram alvo desta ação de extensão 13 turmas do ensino médio público, totalizando 272 estudantes, em três cidades do Paraná (Londrina, Tamarana e São Jerônimo da Serra). Primeiramente 10 diferentes tutoriais foram preparados e alguns destes foram aplicados nas escolas públicas. A metodologia PBL teve uma boa aceitação, tanto pelos estudantes quanto pelos professores. Sendo assim, a aplicação do método PBL para o ensino de Microbiologia para o Ensino Médio se mostrou possí­vel e eficiente. Os alunos de ensino básico adotaram atitudes independentes, reflexivas e crí­ticas, participando como protagonista na construção do próprio conhecimento. Deste modo, a metodologia dialética associada com aulas práticas estimulou o trabalho em equipe, contribuindo para formação de cidadãos mais conscientes em relação aos microrganismos, pois compreenderam o papel destes em diversos aspectos de sua vida, saúde e meio ambiente.

Background/Objectives: Resistance and toxicity limit topical agents for infected burns. We evaluated biogenic silver nanoparticles (bio-AgNPs) combined with Brazilian stingless bee Scaptotrigona bipunctata honey (SB honey). Methods: Bio-AgNPs and honeys from three stingless bee species and Apis mellifera were screened against 11 reference and multidrug-resistant (MDR) strains, including MRSA, MDR Escherichia coli, and MDR Pseudomonas aeruginosa. The most active, SB honey, was combined with bio-AgNPs and assessed by checkerboard (FICI), time-kill, and scanning electron microscopy (SEM). Each agent’s cytotoxicity was determined in HaCaT keratinocytes. Results: Combinations were synergistic (FICI 0.50) against the three Gram-negative strains tested and additive (FICI 0.75) against the three Gram-positive ones, lowering both inhibitory concentrations up to fourfold. The combination reduced viable counts below detection faster than either agent alone at its MBC against MDR P. aeruginosa (30 vs. 60 min) and S. aureus (7 vs. 10–24 h), and matched the fastest single agent against E. coli, at two- to fourfold lower concentrations of both. SEM showed surface damage and incomplete septa. These reduced concentrations fell below each agent’s CC₅₀, increasing the calculated selectivity index. Conclusions: Bio-AgNPs and SB honey act jointly against the reference and MDR strains tested, all associated with burn infections, at concentrations below each agent’s cytotoxic threshold, supporting their further development as a topical antimicrobial.