Category Archives: pathogenic

Research – Lysin and Lytic Phages Reduce Vibrio Counts in Live Feed and Fish Larvae

Posted on May 12, 2024 | Leave a comment

MDPI

Bacteriophage on colorful background

Abstract

Vibrio species are naturally found in estuarine and marine ecosystems, but are also recognized as significant human enteropathogens, often linked to seafood-related illnesses. In aquaculture settings, Vibrio poses a substantial risk of infectious diseases, resulting in considerable stock losses and prompting the use of antimicrobials. However, this practice contributes to the proliferation of antimicrobial-resistant (AMR) bacteria and resistance genes. Our investigation aimed to explore the potential of biological agents such as bacteriophage CH20 and endolysin LysVPp1 in reducing Vibrio bacterial loads in both rotifer and fish larvae. LysVPp1’s lytic activity was assessed by measuring absorbance reduction against various pathogenic Vibrio strains. Phage CH20 exhibited a limited host range, affecting only Vibrio alginolyticus GV09, a highly pathogenic strain. Both CH20 and LysVPp1 were evaluated for their effectiveness in reducing Vibrio load in rotifers or fish larvae through short-setting bioassays. Our results demonstrated the significant lytic effect of endolysin LysVPp1 on strains of Vibrio alginolyticus, Vibrio parahaemolyticus, and Vibrio splendidus. Furthermore, we have showcased the feasibility of reducing the load of pathogenic Vibrio in live feed and fish larvae by using a non-antibiotic-based approach, such as lytic phage and endolysin LysVPp1, thus contributing to the progress of a sustainable aquaculture from a One Health perspective

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Posted in antimicrobial resistance, Antimicrobials, Bacteriophage, Food Microbiology Research, Food Pathogen, Pathogen, pathogenic, Research, Vibrio

Research – An In-Depth Study on the Inhibition of Quorum Sensing by Bacillus velezensis D-18: Its Significant Impact on Vibrio Biofilm Formation in Aquaculture

Posted on May 11, 2024 | Leave a comment

MDPI

Abstract

Amid growing concerns about antibiotic resistance, innovative strategies are imperative in addressing bacterial infections in aquaculture. Quorum quenching (QQ), the enzymatic inhibition of quorum sensing (QS), has emerged as a promising solution. This study delves into the QQ capabilities of the probiotic strain Bacillus velezensis D-18 and its products, particularly in Vibrio anguillarum 507 communication and biofilm formation. Chromobacterium violaceum MK was used as a biomarker in this study, and the results confirmed that B. velezensis D-18 effectively inhibits QS. Further exploration into the QQ mechanism revealed the presence of lactonase activity by B. velezensis D-18 that degraded both long- and short-chain acyl homoserine lactones (AHLs). PCR analysis demonstrated the presence of a homologous lactonase-producing gene, ytnP, in the genome of B. velezensis D-18. The study evaluated the impact of B. velezensis D-18 on V. anguillarum 507 growth and biofilm formation. The probiotic not only controls the biofilm formation of V. anguillarum but also significantly restrains pathogen growth. Therefore, B. velezensis D-18 demonstrates substantial potential for preventing V. anguillarum diseases in aquaculture through its QQ capacity. The ability to disrupt bacterial communication and control biofilm formation positions B. velezensis D-18 as a promising eco-friendly alternative to conventional antibiotics in managing bacterial diseases in aquaculture.

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Posted in Bacillus, Biofilm, Emerging Pathogen, Food Microbiology Research, Food Pathogen, Food Technology, Hurdle Technology, Pathogen, pathogenic, Research, Technology, Vibrio

Research – Long chain unsaturated fatty acids alter growth and reduce biofilm formation of Cronobacter sakazakii

Posted on May 10, 2024 | Leave a comment

Wiley Online

Cronobacter sakazakii is a foodborne pathogen predominately transmitted through contaminated dried foods and affects populations including neonates, infants, and the elderly. Following several recent outbreaks, it is now a notifiable infection in those under 12 months of age. Current control methods include strict manufacturing guidelines, with monitoring of this genus a legal requirement in powdered infant formula production. Fatty acids have long been known as antimicrobials, with long-chain fatty acids increasingly identified as agents that target virulence factors. This study gives insight into the changes promoted by three long-chain unsaturated fatty acids (oleic, linoleic, and α-linolenic) on C. sakazakii growth, morphology, and biofilm formation. Each fatty acid was individually introduced to C. sakazakii 29544 both as a sole carbon source and as an addition to complex media. Following comparison to the untreated control, bacterial cells treated with these fatty acids showed a significant and media-dependent impact on growth and biofilm inhibition. With further characterization, long-chain fatty acids, including α-linolenic acid, could be utilized as a control method with minimal safety constraints regarding their use in the food production environment.

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Posted in Cronobacter sakazakii, cross contamination, Decontamination Microbial, Food Microbiology Research, Food Pathogen, Food Technology, Pathogen, pathogenic, Research, Technology

Research – Fermented Rapeseed and Soybean Alone and in Combination with Macro Algae Inhibit Human and Pig Pathogenic Bacteria In Vitro

Posted on May 10, 2024 | Leave a comment

MDPI

Abstract

Higher plants produce secondary metabolites expressing antimicrobial effects as a defense mechanism against opportunistic microorganisms living in close proximity with the plant. Fermentation leads to bioconversion of plant substrates to these bioactive compounds and their subsequent release via breakdown of plant cell walls. Fermented feed products have recently started to become implemented in the pig industry to reduce overall disease pressure and have been found to reduce events such as post-weaning diarrhea. In this study, we investigate the antimicrobial potential of fermented soybean- and rapeseed-based pig feed supplements with and without added seaweed. The antimicrobial effect was tested in a plate well diffusion assay against a range of known human and livestock pathogenic bacteria. Further, we investigate the metabolite profiles based on liquid-chromatography mass-spectrometry (LC-MS) analysis of the fermented products in comparison to their unfermented constituents. We observed a pronounced release of potential antimicrobial secondary metabolites such as benzoic acids when the plant material was fermented, and a significantly increased antimicrobial effect compared to the unfermented controls against several pathogenic bacteria, especially Salmonella enterica Typhimurium, Listeria monocytogenes, Yersinia enterocolitica, and a strain of atopic dermatitis causing Staphylococcus aureus CC1. In conclusion, fermentation significantly enhances the antimicrobial properties of rapeseed, soybean, and seaweed, offering a promising alternative to zinc oxide for controlling pathogens in piglet feed. This effect is attributed to the release of bioactive metabolites effective against pig production-relevant bacteria.

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Posted in Emerging Pathogen, Food Microbiology Research, Pathogen, pathogenic, Research

Research – Exploring Propolis as a Sustainable Bio-Preservative Agent to Control Foodborne Pathogens in Vacuum-Packed Cooked Ham

Posted on May 4, 2024 | Leave a comment

MDPI

Abstract

The search for natural food additives makes propolis an exciting alternative due to its known antimicrobial activity. This work aims to investigate propolis’ behaviour as a nitrite substitute ingredient in cooked ham (a ready-to-eat product) when confronted with pathogenic microorganisms of food interest. The microbial evolution of Listeria monocytogenes, Staphylococcus aureus, Bacillus cereus, and Clostridium sporogenes inoculated at known doses was examined in different batches of cooked ham. The design of a challenge test according to their shelf life (45 days), pH values, and water activity allowed the determination of the mesophilic aerobic flora, psychotropic, and acid lactic bacteria viability. The test was completed with an organoleptic analysis of the samples, considering possible alterations in colour and texture. The cooked ham formulation containing propolis instead of nitrites limited the potential growth (δ < 0.5 log10) of all the inoculated microorganisms until day 45, except for L. monocytogenes, which in turn exhibited a bacteriostatic effect between day 7 and 30 of the storage time. The sensory analysis revealed the consumer’s acceptance of cooked ham batches including propolis as a natural additive. These findings suggest the functionality of propolis as a promising alternative to artificial preservatives for ensuring food safety and reducing the proliferation risk of foodborne pathogens in ready-to-eat products.

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Posted in Bacillus, Bacillus cereus, Bio-Preservative, Clostridium, Clostridium botulinum, Clostridium sporogenes, Food Microbiology Research, Food Pathogen, Pathogen, pathogenic, Propolis, psychrotrophic bacteria, Research, Staphylococcus aureus

Taiwan – Taipai – Causes clarified in food poisoning case

Posted on May 1, 2024 | Leave a comment

Taipei Times

A suspected food poisoning incident at a Hi-Lai Harbour restaurant at Kaohsiung Arena was not caused by norovirus or rotavirus, but might have been caused by pathogenic bacteria, the Centers for Disease Control (CDC) said yesterday.

Testing for viral pathogens was negative for the two common causes of diarrhea, CDC Deputy Director-General Tseng Shu-hui (曾淑慧) said.

As of 9am on Monday, the number of people who had sought medical attention after dining at the upscale buffet restaurant in Zuoying District (左營) on Friday and Saturday last week had increased to 52 since Saturday, when 11 diners were first reported to have fallen ill, the Kaohsiung Health Department said in a statement.

All of the 52 people reported diarrhea and abdominal pain, while a handful also reported nausea and vomiting, the department said.

It had previously collected specimens from seven people who fell ill after eating at the branch and from 48 employees who handle food at the restaurant, as well as food samples.

Testing on the customers and employees came back negative for viral pathogens, meaning it is likely that pathogenic bacteria were involved, Tseng said.

Common bacteria that cause foodborne illness include Vibrio parahaemolyticus, salmonella, enteropathogenic Escherichia coli, Staphylococcus aureus, Vibrio cholerae and Clostridium botulinum, she said, adding that testing was being conducted to clarify the situation.

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Posted in food bourne outbreak, Food Illness, Food Pathogen, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Pathogen, pathogenic

Research – Assessment of the chemical profile and potential biocontrol of Amphora coffeaeformis against foodborne pathogens and Culex pipiens L. to ensure food safety

Posted on April 21, 2024 | Leave a comment

Wiley Online

Abstract

The extensive use of synthetic antibiotics and insecticides in controlling microbes and insect spreads led to a build-up of resistance strains and caused negative impacts on human health through bioaccumulation in food and the environment. The present study assessed the antimicrobial activity of Amphora coffeaeformis (A. coffeaeformis) ethanolic extract against foodborne pathogenic microbes as well as assessed its ability to control Culex pipiens L. (C. pipiens) larvae. The gas chromatography–mass spectrum (GC/MS) and high-performance liquid chromatography (HPLC) analysis showed that A. coffeaeformis extract was rich with phenolic compounds, organosulfur compounds, carboxylic acids, amino acids, organic quinoline, dipeptide and monosaccharide. The extract of A. coffeaeformis showed antibacterial capability against all tested bacteria, with minimal inhibition concentration (MIC) values ranging from 20.2 to 66.7 g/mL, as well as antifungal effects against all tested mycotoxigenic fungi, with MIC values ranging from 113.62, 68.95 and 49.37 μg/mL mg/mL. Furthermore, the extract showed high larvicidal activity against C. pipiens larvae at 24, 48, and 72 h, respectively. LC50 values decreased gradually with the treatment period. Likewise, the adult emergence and growth index were significantly negatively related to increasing extract concentrations. Moreover, the extract exhibited a noteworthy depletion in the reproductive potential and increased sterility index of C. pipiens females developed of treated larvae. Besides a reduction in egg hatching percent, increase pupal malformations, increase and adult abnormalities. C. pipiens biochemical markers; glutathione-S-transferase, carboxylesterase, acetylcholinesterase, α-esterase and cytochrome P-450 showed significant alteration after the extract exposure. Overall, these findings promise the application possibility of A. coffeaeformis extract as a biopreservator against foodborne pathogens and as bioinsecticides for mosquito control as well.

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Posted in Emerging Pathogen, Food Microbiology Research, Food Pathogen, Pathogen, pathogenic, Research

Researchers Estimate Leafy Greens Foodborne Illness Outbreaks Cost U.S. $5 Billion Annually

Posted on April 18, 2024 | Leave a comment

Food Safety.com

A recent review authored by researchers from Ohio State University has established pathogen-specific foodborne illness burden estimates for leafy greens in the U.S. by combining three outbreak-based attribution models with illness incidence and economic cost models.

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Posted in food bourne outbreak, Food Illness, Food Microbiology Research, Food Pathogen, Foodborne Illness, foodborne outbreak, foodbourne outbreak, Illness, outbreak, Pathogen, pathogenic, Research

Research – Biocontrol of multidrug resistant pathogens isolated from fish farms using silver nanoparticles combined with hydrogen peroxide insight to its modulatory effect

Posted on April 13, 2024 | Leave a comment

Nature

This study was divided into two parts. The first part involved the isolation, and detection of the prevalence and antimicrobial resistance profile of Aeromonas hydrophila, Pseudomonas aeruginosa, and Vibrio species from Nile tilapia fish and marine aquatic water. One hundred freshly dead Nile tilapia fish were collected from freshwater aquaculture fish farms located in Al-Abbassah district, Sharkia Governorate, and 100 samples of marine aquatic water were collected from fish farms in Port Said. The second part of the study focused on determining the in vitro inhibitory effect of dual-combination of AgNPs-H2O2 on bacterial growth and its down regulatory effect on crucial virulence factors using RT-PCR. The highest levels of A. hydrophila and P. aeruginosa were detected in 43%, and 34% of Nile tilapia fish samples, respectively. Meanwhile, the highest level of Vibrio species was found in 37% of marine water samples. Additionally, most of the isolated A. hydrophila, P. aeruginosa and Vibrio species exhibited a multi-drug resistance profile. The MIC and MBC results indicated a bactericidal effect of AgNPs-H2O2. Furthermore, a transcriptional modulation effect of AgNPs-H2O2 on the virulence-associated genes resulted in a significant down-regulation of aerA, exoU, and trh genes in A. hydrophila, P. aeruginosa, and Vibrio spp., respectively. The findings of this study suggest the effectiveness of AgNPs-H2O2 against drug resistant pathogens related to aquaculture.

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Posted in Aeromonas, antimicrobial resistance, Antimicrobials, Emerging Pathogen, Food Pathogen, Pathogen, pathogenic, Pseudomonas aeruginosa, Vibrio, Vibrio cholera, Vibrio parahaemolyticus, Vibrio vulnificus

Research – Differences in Biofilm Formation of Listeria monocytogenes and Their Effects on Virulence and Drug Resistance of Different Strains

Posted on April 6, 2024 | Leave a comment

MDPI

Abstract

Listeria monocytogenes is recognized as one of the primary pathogens responsible for foodborne illnesses. The ability of L. monocytogenes to form biofilms notably increases its resistance to antibiotics such as ampicillin and tetracycline, making it exceedingly difficult to eradicate. Residual bacteria within the processing environment can contaminate food products, thereby posing a significant risk to public health. In this study, we used crystal violet staining to assess the biofilm-forming capacity of seven L. monocytogenes strains and identified ATCC 19112 as the strain with the most potent biofilm-forming. Subsequent fluorescence microscopy observations revealed that the biofilm-forming capacity was markedly enhanced after two days of culture. Then, we investigated into the factors contributing to biofilm formation and demonstrated that strains with more robust extracellular polymer secretion and self-agglutination capabilities exhibited a more pronounced ability to form biofilms. No significant correlation was found between surface hydrophobicity and biofilm formation capability. In addition, we found that after biofilm formation, the adhesion and invasion of cells were enhanced and drug resistance increased. Therefore, we hypothesized that the formation of biofilm makes L. monocytogenes more virulent and more difficult to remove by antibiotics. Lastly, utilizing RT-PCR, we detected the expression levels of genes associated with biofilm formation, including those involved in quorum sensing (QS), flagellar synthesis, and extracellular polymer production. These genes were significantly upregulated after biofilm formation. These findings underscore the critical relationship between extracellular polymers, self-agglutination abilities, and biofilm formation. In conclusion, the establishment of biofilms not only enhances L. monocytogenes’ capacity for cell invasion and adhesion but also significantly increases its resistance to drugs, presenting a substantial threat to food safety.

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Posted in Biofilm, Food Microbiology Research, Food Pathogen, Listeria, Listeria monocytogenes, Pathogen, pathogenic, Research