Genetic heterogeneity of Escherichia coli isolated from pasteurized milk in State of Paraná, Brazil

A contaminação de alimentos por patógenos entéricos é uma das principais causas de doenças diarréicas em todo o mundo, resultando em altas taxas de morbidade e mortalidade e perdas econômicas significativas. As bactérias são importantes agentes de doenças de origem alimentar, particularmente Escherichia coli diarreiogênicas. O presente estudo teve como objetivo avaliar a diversidade genética e a resistência a antimicrobianos de E. coli isoladas de leite pasteurizado, processados em 21 laticínios na região noroeste do Paraná - Brasil. Os 95 isolados de E. coli foram submetidos a testes de suscetibilidade aos antimicrobianos de acordo com as recomendações do Clinical and Laboratory Standards Institute e avaliados genotipicamente por ERIC-PCR (Enterobacterial Repetitive Intergenic Consensus - Polymerase Chain Reaction). O principal perfil de resistência encontrado entre os isolados foi resistência à cefalotina (55,78%). ERIC-PCR revelou alta diversidade genética, agrupando os 95 isolados bacterianos em 90 diferentes perfis genotípicos. Estes resultados mostraram uma população heterogênea de E. coli em amostras de leite produzido na região noroeste do Paraná e a necessidade de boas práticas na manipulação de todo o processamento de leite pasteurizado, a fim de reduzir o risco de doenças transmitidas por alimentos.Food contamination caused by enteric pathogens is a major cause of diarrheal disease worldwide, resulting in high morbidity and mortality and significant economic losses. Bacteria are important agents of foodborne diseases, particularly diarrheagenic Escherichia coli. The present study assessed the genetic diversity and antimicrobial resistance of E. coli isolates from pasteurized milk processed in 21 dairies in northwestern State of Parana, Brazil. The 95 E. coli isolates were subjected to antimicrobial susceptibility testing according to the recommendations of the Clinical and Laboratory Standards Institute and assessed genotypically by Enterobacterial Repetitive Intergenic Consensus-Polymerase Chain Reaction (ERIC-PCR). The highest rate of resistance was observed for cephalothin (55.78%). ERIC-PCR revealed high genetic diversity, clustering the 95 bacterial isolates into 90 different genotypic patterns. These results showed a heterogeneous population of E. coli in milk samples produced in the northwestern region of Paraná and the need for good manufacturing practices throughout the processing of pasteurized milk to reduce the risk of foodborne illnesses

Antibacterial and antibiofilm activity of carvacrol against Salmonella enterica serotype Typhimurium

The present study evaluated the antibacterial and antibiofilm activity of carvacrol against Salmonella Typhimurium. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined and the time-kill curve and scanning electron microscopy (SEM) were performed to evaluate antibacterial activity. Antibiofilm activity was evaluated by quantifying total biomass using crystal violet assay, and metabolic activity was determined using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay. The action of carvacrol against preformed biofilm on polypropylene and stainless steel was also evaluated by colony counting and SEM. The MIC and MBC was 312 µg mL-1. Carvacrol at MIC and 2 x MIC eliminated cells after 6 and 1 h of treatment, respectively, as exhibited in the time-kill curve. The greatest reduction in biofilm biomass and metabolic activity was 1,719 OD550 and 0,089 OD550 respectively, both at 4 x MIC of carvacrol. In carvacrol treated biofilms of S. Typhimurium on polypropylene, a reduction of 5.12 log was observed with 4 x MIC, while on stainless steel, carvacrol at 4 x MIC reduced bacterial counts by 5 log. The results showed that carvacrol exhibits antibacterial activity and can be used as an alternative for the control of S. Typhimurium biofilms

Use of nanoencapsulated curcumin against vegetative cells and spores of Alicyclobacillus spp. in industrialized orange juice

Pathogenic and deteriorating bacteria are a great concern to food safety. In this sense, the present study evaluated the fight against microbial contamination through the use of nanoparticles containing curcumin, in addition to analyzing the physical properties of these nanoparticles. Efficient curcumin encapsulation was determined by Fourier transform infrared spectra evaluation and differential scanning calorimetry. Transmission electron microscopy images showed irregular shaped nanoparticles with broad size distribution (20–250 nm). The antibacterial activity was considered satisfactory, since curcumin in the form of nanoparticles demonstrated antimicrobial and antibacterial activity superior to curcumin in its free form, against both pathogenic bacteria, such as Staphylococcus aureus (MIC 125 μg/mL), and deteriorates, such as Alicyclobacillus acidoterrestris (MIC 62.5 μg/mL). Since curcumin nanoparticles may be consumed as a food additive, the bioactive properties of the nanoencapsulated curcumin were also evaluated in relation to antioxidant capacity (Thiobarbituric acid reactive substances (TBARS) and oxidative hemolysis inhibition assays) and cytotoxicity against four carcinoma cell lines, as well as two non-tumor cells. As a proof of concept, nanoparticles were incorporated in orange juice, with the juice maintaining satisfactory pH, °Brix, and color stability, during three days of storage (8 °C).This study was financed in part by the Coordenaç˜ao de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. The authors thank the “Central Analítica Multiusu´ario da UTFPR Campo Mourão” (CAMulti-CM) for the analyses. Fernanda V. Leimann (process 039/2019) would like to thank Fundação Araucária (CP 15/2017- Programa de Bolsas de Produtividade em Pesquisa e Desenvolvimento Tecnológico) and CNPq (process number 421541/2018-0, Chamada Universal MCTIC/CNPq n◦ 28/2018). The authors are also grateful to the Foundation for Science and Technology (FCT, Portugal) for financial support through national funds FCT/MCTES to CIMO (UIDB/00690/ 2020); L. Barros and C. Pereira also thank FCT, P.I., through the institutional scientific employment program-contract.info:eu-repo/semantics/publishedVersio

Qualidade microbiológica e vida útil de filés defumados de tilápia-do-nilo sob refrigeração ou congelamento

O objetivo deste trabalho foi avaliar a qualidade microbiológica e a vida útil de filés de tilápia-do-nilo, submetidos a diferentes métodos de defumação e condições de armazenamento. Foram utilizados dois processos de defumação (a frio ou a quente), em filés com ou sem pigmentação. Os produtos foram armazenados sob refrigeração ou congelados, e monitorados por 28 dias para avaliação da vida útil. Os filés congelados foram monitorados continuamente por 146 dias, apenas para a análise de ácido tiobarbitúrico (TBA). Defumação a quente e a frio reduziram a quantidade de coliformes, respectivamente em 99,78% e 97,80%. O armazenamento do produto sob refrigeração permitiu a redução de 99,73% dos coliformes, e o armazenamento sob congelamento os reduziu em 99,83%. Os valores encontrados de coliformes fecais estiveram dentro do limite permitido. Os valores de TBA nos filés atingiram o máximo no 14o dia de armazenamento. Os valores de TBA nos tratamentos sob refrigeração foram superiores aos daqueles sob congelamento e, também, em filés defumados a frio, em comparação aos defumados a quente. O processo de defumação a quente, com posterior armazenamento sob congelamento, é a técnica mais apropriada para assegurar qualidade e maior período de vida útil para os filés de tilápia-do-nilo, independentemente do processo de pigmentação

Resistance profile to antimicrobials of Salmonella spp. isolated from human infections

The purpose of this study was to analyse the profile of antimicrobial resistance among 21 strains of Salmonella isolated from patients with gastroenteritis symptom. It was observed that S. enteritidis was the serotype prevalent. These strains were sensitive to the majority of the antimicrobials tested, however, high resistance was observed in S. typhimurium and S. enterica subsp. enterica serotype 4,5,12:i:-. Surveillance and an efficient monitoring should be priority for the public health for the containment of antimicrobial resistance in foodborne infections.O objetivo deste estudo foi analisar o perfil de resistência à antimicrobianos, de Salmonella isoladas de 21 amostras provenientes de pacientes com sintomatologia de gastroenterite. Verificou-se que S. enteritidis foi o sorotipo com maior prevalência. Estas cepas mostraram-se sensíveis à maioria dos antimicrobianos testados, no entanto, as cepas S. typhimurium e S. enterica subsp. enterica sorotipo 4,5,12:i:-, mostraram-se resistentes à vários antimicrobianos. Vigilância e um monitoramento eficiente, para diminuir a resistência antimicrobiana em microrganismos que causam infecções veiculadas por alimentos, devem ser prioridade para a saúde pública

Photodynamic inactivation as an emergent strategy against foodborne pathogenic bacteria in planktonic and sessile states

Foodborne microbial diseases are still considered a growing public health problem worldwide despite the global continuous efforts to ensure food safety. The traditional chemical and thermal-based procedures applied for microbial growth control in the food industry can change the food matrix and lead to antimicrobial resistance. Moreover, currently applied disinfectants have limited efficiency against biofilms. Therefore, antimicrobial photodynamic therapy (aPDT) has become a novel alternative for controlling foodborne pathogenic bacteria in both planktonic and sessile states. The use of aPDT in the food sector is attractive as it is less likely to cause antimicrobial resistance and it does not promote undesirable nutritional and sensory changes in the food matrix. In this review, aspects on the antimicrobial photodynamic technology applied against foodborne pathogenic bacteria and studied in recent years are presented. The application of photodynamic inactivation as an antibiofilm strategy is also reviewed

Antimicrobial Photodynamic Inactivation Mediated by Rose Bengal and Erythrosine Is Effective in the Control of Food-Related Bacteria in Planktonic and Biofilm States

The thermal and chemical-based methods applied for microbial control in the food industry are not always environmentally friendly and may change the nutritional and organoleptic characteristics of the final products. Moreover, the efficacy of sanitizing agents may be reduced when microbial cells are enclosed in biofilms. The objective of this study was to investigate the effect of photodynamic inactivation, using two xanthene dyes (rose bengal and erythrosine) as photosensitizing agents and green LED as a light source, against Staphylococcus aureus, Listeria innocua, Enterococcus hirae and Escherichia coli in both planktonic and biofilm states. Both photosensitizing agents were able to control planktonic cells of all bacteria tested. The treatments altered the physicochemical properties of cells surface and also induced potassium leakage, indicating damage of cell membranes. Although higher concentrations of the photosensitizing agents (ranging from 0.01 to 50.0 μmol/L) were needed to be applied, the culturability of biofilm cells was reduced to undetectable levels. This finding was confirmed by the live/dead staining, where propidium iodide-labeled bacteria numbers reached up to 100%. The overall results demonstrated that photoinactivation by rose bengal and erythrosine may be a powerful candidate for the control of planktonic cells and biofilms in the food sector