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Virulence Dec 2024The global surge in multidrug-resistant bacteria owing to antibiotic misuse and overuse poses considerable risks to human and animal health. With existing antibiotics...
The global surge in multidrug-resistant bacteria owing to antibiotic misuse and overuse poses considerable risks to human and animal health. With existing antibiotics losing their effectiveness and the protracted process of developing new antibiotics, urgent alternatives are imperative to curb disease spread. Notably, improving the bactericidal effect of antibiotics by using non-antibiotic substances has emerged as a viable strategy. Although reduced nicotinamide adenine dinucleotide (NADH) may play a crucial role in regulating bacterial resistance, studies examining how the change of metabolic profile and bacterial resistance following by exogenous administration are scarce. Therefore, this study aimed to elucidate the metabolic changes that occur in (), which exhibits resistance to various antibiotics, following the exogenous addition of NADH using metabolomics. The effects of these alterations on the bactericidal activity of neomycin were investigated. NADH enhanced the effectiveness of aminoglycoside antibiotics against ATCC15947, achieving bacterial eradication at low doses. Metabolomic analysis revealed that NADH reprogrammed the ATCC15947 metabolic profile by promoting purine metabolism and energy metabolism, yielding increased adenosine triphosphate (ATP) levels. Increased ATP levels played a crucial role in enhancing the bactericidal effects of neomycin. Moreover, exogenous NADH promoted the bactericidal efficacy of tetracyclines and chloramphenicols. NADH in combination with neomycin was effective against other clinically resistant bacteria, including , methicillin-resistant , and . These results may facilitate the development of effective approaches for preventing and managing -induced infections and multidrug resistance in aquaculture and clinical settings.
Topics: Edwardsiella tarda; Anti-Bacterial Agents; NAD; Aminoglycosides; Animals; Fish Diseases; Microbial Sensitivity Tests; Enterobacteriaceae Infections; Adenosine Triphosphate; Neomycin; Drug Synergism; Metabolomics; Drug Resistance, Multiple, Bacterial
PubMed: 38884466
DOI: 10.1080/21505594.2024.2367647 -
MethodsX Jun 2024The consumption of avocados and their products has been linked to outbreaks of illness caused by and . These pathogens have been isolated from avocados collected from...
The consumption of avocados and their products has been linked to outbreaks of illness caused by and . These pathogens have been isolated from avocados collected from farms and markets. After contact with the avocado epicarp, the cells of and can become loosely attached (LA) by suspension in a film of water and attraction by electrostatic forces, or strongly attached (SA) by physical and irreversible attachment mechanisms. Attached cells may have greater resistance to agents used to decontaminate the fruit. The effect of applying wet steam (WS) to the epicarp of Hass avocados on the reduction LA and SA counts of and was evaluated as a function of the exposure time. The inoculated avocados were washed and exposed to WS for 30, 45, and 60 s inside a treatment chamber. was found to be more susceptible to WS than . The efficacy of steam in reducing LA and SA cell numbers was similar for both pathogens. Steaming avocados for 60 s reduced LA and cells by 4.6 and 4.8 log CFU/avocado, whereas SA cells were decreased by 5.2 and 4.4 log CFU/avocado, respectively.•Steaming the avocados for 60 s produced the greatest reduction in loosely and strongly attached cells for both pathogens.•Wet steam treatment efficiently eliminated the loosely and strongly attached cells of both pathogens.•The attached cells showed greater resistance to steam treatment than .
PubMed: 38883590
DOI: 10.1016/j.mex.2024.102776 -
Frontiers in Microbiology 2024causes listeriosis, an infectious and potentially fatal disease of animals and humans. A diverse network of transcriptional regulators, including LysR-type catabolite...
causes listeriosis, an infectious and potentially fatal disease of animals and humans. A diverse network of transcriptional regulators, including LysR-type catabolite control protein C (CcpC), is critical for the survival of and its ability to transition into the host environment. In this study, we explored the physiological and genetic consequences of deleting and the effects of such deletion on the ability of to cause disease. We found that deletion did not impact hemolytic activity, whereas it resulted in significant reductions in phospholipase activities. Western blotting revealed that the Δ strain produced significantly reduced levels of the cholesterol-dependent cytolysin LLO relative to the wildtype F2365 strain. However, the Δ mutant displayed no significant intracellular growth defect in macrophages. Furthermore, Δ strain exhibited reduction in plaque numbers in fibroblasts compared to F2365, but plaque size was not significantly affected by deletion. In a murine model system, the Δ strain exhibited a significantly reduced bacterial burden in the liver and spleen compared to the wildtype F2365 strain. Interestingly, the deletion of this gene also enhanced the survival of under conditions of HO-induced oxidative stress. Transcriptomic analyses performed under HO-induced oxidative stress conditions revealed that DNA repair, cellular responses to DNA damage and stress, metalloregulatory proteins, and genes involved in the biosynthesis of peptidoglycan and teichoic acids were significantly induced in the deletion strain relative to F2365. In contrast, genes encoding internalin, 1-phosphatidylinositol phosphodiesterase, and genes associated with sugar-specific phosphotransferase system components, porphyrin, branched-chain amino acids, and pentose phosphate pathway were significantly downregulated in the deletion strain relative to F2365. This finding highlights CcpC as a key factor that regulates physiology and responses to oxidative stress by controlling the expression of important metabolic pathways.
PubMed: 38881664
DOI: 10.3389/fmicb.2024.1403694 -
International Journal of Food... Jun 2024To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C...
To our knowledge, this study is the first to elucidate the bactericidal efficacy of unpeeled carrots (hereafter referred to as carrots) pretreated with Ultra Violet-C (UV-C) against subsequent contamination with Listeria monocytogenes. Carrots pretreated with UV-C (240 mJ/cm) exhibited a significant antilisterial effect within 2 h. In fact, the population of UV-C-pretreated carrots decreased from 7.94 log CFU/cm to levels below the limit of detection (LOD; <1.65 log CFU/cm) within 24 h. For carrots that were not pretreated with UV-C, 3-4 log reductions were found after 24 h. Carrots pretreated with UV-C exhibited antimicrobial activity against another gram-positive pathogen, Staphylococcus aureus, but not against the gram-negative pathogens, E. coli O157:H7 and Salmonella enterica. Pretreatment with UV-C created a lasting antimicrobial effect as introducing L. monocytogenes on carrots, 72 h post-UV-C treatment, still maintained the antilisterial effect. Notably, all UV-C doses in the range of 48-240 mJ/cm induced a lasting antilisterial effect. The bactericidal effects against L. monocytogenes were confirmed in three varieties of washed and unwashed carrots (Danvers, Nantes, and Chantenay). Fluorescence microscopy confirmed the bactericidal effect of UV-C-pretreated carrots on the survival of L. monocytogenes. Conclusively, pretreating carrots with UV-C can reduce the population of L. monocytogenes to levels below the LOD and may further prevent pathogen growth during cold storage. Additional studies are necessary to discern the mechanism underlying the bactericidal efficacy of UV-C-pretreated carrots.
PubMed: 38878705
DOI: 10.1016/j.ijfoodmicro.2024.110800 -
Food Research International (Ottawa,... Aug 2024This study aimed to evaluate the microbiome, resistome and virulome of two types of Portuguese cheese using high throughput sequencing (HTS). Culture-dependent...
Metagenomic analysis of the bacterial microbiome, resistome and virulome distinguishes Portuguese Serra da Estrela PDO cheeses from similar non-PDO cheeses: An exploratory approach.
This study aimed to evaluate the microbiome, resistome and virulome of two types of Portuguese cheese using high throughput sequencing (HTS). Culture-dependent chromogenic methods were also used for certain groups/microorganisms. Eight samples of raw ewe's milk cheese were obtained from four producers: two producers with cheeses with a PDO (Protected Designation of Origin) label and the other two producers with cheeses without a PDO label. Agar-based culture methods were used to quantify total mesophiles, Enterobacteriaceae, Escherichia coli, Staphylococcus, Enterococcus and lactic acid bacteria. The presence of Listeria monocytogenes and Salmonella was also investigated. The selected isolates were identified by 16S rRNA gene sequencing and evaluated to determine antibiotic resistance and the presence of virulence genes. The eight cheese samples analyzed broadly complied with EC regulations in terms of the microbiological safety criteria. The HTS results demonstrated that Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus plantarum, Lacticaseibacillus rhamnosus, Enterococcus durans and Lactobacillus coryniformis were the most prevalent bacterial species in cheeses. The composition of the bacterial community varied, not only between PDO and non-PDO cheeses, but also between producers, particularly between the two non-PDO cheeses. Alpha-diversity analyses showed that PDO cheeses had greater bacterial diversity than non-PDO cheeses, demonstrating that the diversity of spontaneously fermented foods is significantly higher in cheeses produced without the addition of food preservatives and dairy ferments. Despite complying with microbiological regulations, both PDO and non-PDO cheeses harbored potential virulence genes as well as antibiotic resistance genes. However, PDO cheeses exhibited fewer of these virulence and antibiotic resistance genes compared to non-PDO cheeses. Therefore, the combination of conventional microbiological methods and the metagenomic approach could contribute to improving the attribution of the PDO label to this type of cheese.
Topics: Cheese; Microbiota; Portugal; Food Microbiology; Animals; Metagenomics; Bacteria; RNA, Ribosomal, 16S; Drug Resistance, Bacterial; Sheep; High-Throughput Nucleotide Sequencing; Milk; Enterococcus
PubMed: 38876593
DOI: 10.1016/j.foodres.2024.114556 -
Food Research International (Ottawa,... Aug 2024Listeria monocytogenes, a widespread food-borne pathogen, utilizes diverse growth substrates including mono- and di-saccharides via PEP-phosphotransferase (PTS) systems....
Listeria monocytogenes, a widespread food-borne pathogen, utilizes diverse growth substrates including mono- and di-saccharides via PEP-phosphotransferase (PTS) systems. We evaluated a collection of L. monocytogenes isolates of different origins for their ability to utilize lactose, a disaccharide composed of galactose and glucose and the main carbon source in milk and dairy products. Notably, the dairy-associated outbreak strain F2365 could not utilize lactose efficiently, conceivably due to a frameshift mutation (lacR) resulting in a truncated LacR. Transcriptional activator LacR is involved in the expression of two PTS systems, encoded by the lpo operon lmo1718-1720 in combination with lmo2708 and the lmo2683-2685 operon, and linked to lactose and/or cellobiose metabolism in L. monocytogenes. Via experimental evolution of the ancestral strain F2365, an evolved isolate F2365 EV was obtained which showed enhanced growth and metabolism of lactose. Using the lactose-positive model strain L. monocytogenes EGDe as a control, HPLC experiments showed that EGDe and F2365 EV could consume lactose and utilize the glucose moiety, while the galactose moiety was exported from the cells. Genome sequencing of F2365 EV found the original lacR mutation was still present but an additional point mutation lmo2766 had occurred, resulting in an amino acid substitution in the putative regulator Lmo2766. The lmo2766 gene is located next to operon lmo2761-2765 with putative PTS genes in the genome. Notably, comparative RNAseq analysis confirmed that the lmo2761-2765 operon was strongly upregulated in F2365 EV in the presence of lactose but not in EGDe and F2365. Conversely, the LacR-regulated lpo operon, lmo2708, and lmo2683-2685 operon were only upregulated in EGDe. Additional growth and HPLC experiments, using mutants constructed in lactose-positive L. monocytogenes EGDe, showed reduced growth of the EGDe lacR mutant with no utilization of lactose, while the double mutant EGDe lacRlmo2766 showed enhanced growth and lactose utilization. Hence, these results demonstrate that an amino acid substitution in the Lmo2766 regulator activates a previously silent lactose utilization pathway encoded by PTS operon lmo2761-2765, facilitating the growth and metabolism of L. monocytogenes with lactose as a substrate. This finding enhances our understanding of the metabolic capabilities and adaptability of L. monocytogenes, offering a broader view of the lactose utilization capacity of this pathogen.
Topics: Listeria monocytogenes; Lactose; Operon; Bacterial Proteins; Disease Outbreaks; Gene Expression Regulation, Bacterial; Food Microbiology; Milk; Animals; Dairy Products
PubMed: 38876592
DOI: 10.1016/j.foodres.2024.114554 -
Journal of Food Protection Jun 2024The efficacy of a sanitizer in biofilm removal may be influenced by a combination of factors such as sanitizer exposure time and concentration, bacterial species,...
The efficacy of a sanitizer in biofilm removal may be influenced by a combination of factors such as sanitizer exposure time and concentration, bacterial species, surface topography and shear stresses. We employed an inline biofilm reactor to investigate the interactions of these variables on biofilm removal with chlorine. The CDC bioreactor was used to grow E. coli O157:H7 and L. monocytogenes biofilms as a single species or with R. insidiosa as a dual-species biofilm on stainless steel, PTFE, and EPDM coupons at shear stresses 0.368 and 2.462 N/m for 48-hours. Coupons were retrieved from a CDC bioreactor and placed in an inline biofilm reactor and 100, 200 or 500 ppm of chlorine was supplied for 1-and-4 min. Bacterial populations in the biofilms were quantified pre- and post-treatment by plating on selective media. After chlorine treatment, reduction (Log CFU/cm) in pathogen populations obtained from three replicates were analyzed for statistical significance. A 1-min chlorine treatment (500 ppm), on dual-species E. coli O157:H7 biofilms grown at high shear stress of 2.462 N/m resulted in significant E. coli O157:H7 reductions on SS 316L (2.79 log CFU/cm) and PTFE (1.76 log CFU/cm). Similar trend was also observed for biofilm removal after a 4-min chlorine treatment. Single species E. coli O157:H7 biofilms exhibited higher resistance to chlorine when biofilms were developed at high shear stress. The effect of chlorine in L. monocytogenes removal from dual-species biofilms was dependent primarily on the shear stress at which they were formed rather than the surface topography of materials. Besides surface topography, shear stresses at which biofilms were formed also influenced the effect of sanitizer. The removal of E. coli O157:H7 biofilms from EPDM material may require critical interventions due to difficulty in removing this pathogen. The inline biofilm reactor is novel tool to evaluate the efficacy of a sanitizer in bacterial biofilm removal.
PubMed: 38876365
DOI: 10.1016/j.jfp.2024.100314 -
Journal of Food Protection Jun 2024The current study assessed (i) the microbiological safety level profiles (MSLPs) of milkmen's hands and milking containers and (ii) the influence of hygiene and handling...
The current study assessed (i) the microbiological safety level profiles (MSLPs) of milkmen's hands and milking containers and (ii) the influence of hygiene and handling practices on MSLPs of raw and cultured milk, from six informal dairy farms in Zimbabwe. Interviews and direct observations were carried out during the assessment of hygiene and handling practices at six farms designated A to F. Microbiological criteria of the following six microbiological parameters: Total Bacterial Counts (TBCs), Coliform Counts (CCs), Total Escherichia coli Counts (TECs), Salmonella spp., Listeria monocytogenes and Klebsiella pneumonia, were used to determine contamination level (CL) at four different critical sampling locations (CSLs). The CSLs were raw milk (CSL1), cultured milk (CSL2), milkmen's hands (CSL3), and milking containers (CSL4). The microbiological criteria of the six microbiological parameters were used to score CLs as: intolerable (0), poor to average (1), average (2), and good (3). MSLPs at each CSL for the six farms were computed based on the CL scores to a maximum score of 18. A total of 192 samples were collected and analyzed. Salmonella spp. and L. monocytogenes were not detected at all the CSLs. All the farms failed to achieve a maximum MSLP score of 18 at all the CSLs. The relationship between MSLPs and hygiene and handling practices was tested using point-biserial correlation coefficients. The correlation study revealed that handling and hygiene practices (such as the duration between milking and storage, the type of milking container utilized at farms, the frequency of cleaning the milking parlor, the water source for hand and equipment washing, and the use of hand sanitizers) generally influenced the MSLPs on the farms. Both training and improvement in infrastructure are needed to improve the quality of milk and its products produced and sold in the informal value chain in Zimbabwe.
PubMed: 38871224
DOI: 10.1016/j.jfp.2024.100313 -
Journal of Food Protection Jun 2024In recent years, there have been numerous recalls of frozen vegetable products due to Listeria monocytogenes contamination, which causes listeriosis. In pregnant women,...
In recent years, there have been numerous recalls of frozen vegetable products due to Listeria monocytogenes contamination, which causes listeriosis. In pregnant women, listeriosis can cause miscarriage, stillbirth, and other serious complications. Manufacturing guidelines are created with the intention that frozen vegetables will be cooked prior to consumption. However, consumers may prepare and eat frozen vegetables without prior cooking. Therefore, it is necessary to assess behaviors that could be risky for L. monocytogenes exposure. A 10-question online survey was distributed to women between the ages of 18-54 to investigate frozen vegetable consumption behaviors. The prevalence of uncooked frozen vegetable consumption, reading preparation instructions, and listeriosis knowledge was assessed. Data were analyzed using logistic and ordered logit regression. Of 1,001 complete responses, 531 (53%) indicated that they consumed frozen vegetables in the past week, and of those 35.6% (n = 189) indicated that they consumed frozen vegetables without prior heating. Women who had not heard of listeriosis and had not read preparation instructions had significantly higher odds of uncooked frozen vegetable consumption (Odds Ratio (OR): 2.30, 95% Confidence Interval (CI): 1.48, 3.55; OR: 1.85, 95% CI: 1.13, 3.01, respectively). These results will guide future research on safe food handling practices for frozen vegetable products. The findings support the need for updating public health guidelines to include frozen vegetables as foods that are risky for listeriosis in pregnancy. Additionally, these findings have implications for future research to inform food policy governing labeling regulation on frozen vegetable products to reflect current consumer behavior.
PubMed: 38871223
DOI: 10.1016/j.jfp.2024.100315 -
Microbiology Resource Announcements Jun 2024, a concerning foodborne pathogen, causes severe infections in vulnerable subjects such as pregnant women and the elderly. In this article, we present the complete...
, a concerning foodborne pathogen, causes severe infections in vulnerable subjects such as pregnant women and the elderly. In this article, we present the complete genome sequence of P4_LIS, an isolated from a patient with invasive bacteria infection.
PubMed: 38864617
DOI: 10.1128/mra.01240-23