Clostridium perfringens: A Dynamic Foodborne Pathogen

Impact of pH and High-Pressure Pasteurization on the Germination and Development of Clostridium perfringens Spores under Hyperbaric Storage versus Refrigeration

This study aimed to evaluate hyperbaric storage at room temperature (75-200 MPa, 30 days, 18-23 °C, HS/RT) on Clostridium perfringens spores in brain-heart infusion broth (BHI-broth) at pH 4.50, 6.00, and 7.50 and coconut water (pH 5.40). Both matrices were also pasteurized by high pressure processing (600 MPa, 3 min, 17 °C, HPP) to simulate commercial pasteurization followed by HS, in comparison with refrigeration (5 °C, RF). The results showed that, at AP/RT, spores' development occurred, except at pH 4.50 in BHI-broth, while for RF, no changes occurred along storage. Under HS, at pH 4.50, neither spore development nor inactivation occurred, while at pH 6.00/7.50, inactivation occurred (≈2.0 and 1.0 logs at 200 MPa, respectively). Coconut water at AP/RT faced an increase of 1.6 logs of C. perfringens spores after 15 days, while for RF, no spore development occurred, while the inactivation of spores under HS happened (≈3 logs at 200 MPa). HPP prior to HS seems to promote a subsequent inactivation of C. perfringens spores in BHI-broth at pH 4.50, which is less evident for other pHs. For HPP coconut water, the inactivation levels under HS were lower (≈2.0 logs at 200 MPa). The Weibull model well described the inactivation pattern observed. These results suggest that HS/RT can be simultaneously used as a tool to avoid C. perfringens spores' development, as well as for its inactivation, without the application of high temperatures that are required to inactivate these spores.

Antimicrobial Effects of Plant-Based Supplements on Gut Microbial Diversity in Small Ruminants

Every year in the United States, approximately 48 million people are affected by bacterial illnesses that are transmitted through food, leading to 3000 fatalities. These illnesses typically stem from food animals and their by-products, which may harbor dangerous pathogens like Salmonella enterica, Listeria monocytogenes, enterohemorrhagic Escherichia coli O157:H7, and Campylobacter jejuni. Factors that contribute to contamination include manure used as a soil amendment, exposure to polluted irrigation water, and contact with animals. To improve food safety, researchers are studying pre-slaughter intervention methods to eliminate bacterial contamination in live animals. While small ruminants are vital to global agriculture and income generation for small farms, traditional feeding practices involve supplements and antibiotics to boost performance, which contributes to antibiotic resistance. Hence, researchers are looking for friendly bacterial strains that enhance both animal and human health without impacting livestock productivity. The global trend is to minimize the use of antibiotics as feed supplements, with many countries prohibiting or limiting their use. The aim of this review is to provide a comprehensive insight on the antioxidant capabilities, therapeutic attributes, and applications of bioactive compounds derived from sweet potato tops (SPTs), rice bran (RB) and radish tops (RTs). This overview provides an insight on plant parts that are abundant in antioxidant and prebiotic effects and could be used as value-added products in animal feed and pharmaceutical applications. This review was based on previous findings that supplementation of basal diets with natural supplements represents a multifaceted intervention that will become highly important over time. By remarkably reducing the burden of foodborne pathogens, they apply to multiple species, are cheap, do not require withdrawal periods, and can be applied at any time in food animal production.

Effect of allyl isothiocyanate on the growth and virulence of Clostridium perfringens and its application on cooked pork

The objective of this study is to explore the antibacterial action modes and virulence-inhibitory effects of allyl isothiocyanate (AITC) against Clostridium perfringens (C. perfringens). The minimum inhibitory concentration (MIC) of AITC against vegetative cells of Cp 13124 was 0.1 μL/mL, and the time-kill kinetics analysis revealed that AITC could significantly suppress the growth of Cp 13124. According to the results from scanning electron microscopy (SEM), fluorescence microscopy, and UV absorbance substance detection, the cell membrane of Cp 13124 was damaged upon AITC treatment, causing a loss of integrity and the release of intracellular substances. Meanwhile, the fluorescence quenching experiment indicated the interaction of AIT-C with membrane proteins, which caused changes in the conformation of membrane proteins. Measurement of reactive oxygen species (ROS) and flow cytometry analysis demonstrated that AITC could induce apoptosis through oxidative stress. The formation of Cp 13124 biofilms was inhibited by AITC using the crystalline violet method, which was possibly related to the inhibition of sliding motility. Finally, low concentrations of AITC could be used as an antibacterial agent to inhibit the outgrowth of Cp 13124 in cooked pork, suggesting that AITC is a promising candidate for novel preservatives in the meat business.

Antimicrobial Activity of Peptides Produced by Lactococcus lactis subsp. lactis on Swine Pathogens

Swine production is of great importance worldwide and has huge economic and commercial impact. Due to problems with bacterial infection, the use of antimicrobials has increased in the last decades, particularly in Latin America and Asia. This has led to concerns about antimicrobial resistance, which poses risks to human health and the environment. The use of probiotic organisms has been proposed as an alternative to this use, as these beneficial bacteria can produce antimicrobial peptides, such as bacteriocins, which allow the induction of inhibitory effects against pathogenic microorganisms. Among probiotics, some bacteria stand out with the inhibition of animal pathogens. The bacteriocin-like inhibitory substances (BLISs) of Lactococcus lactis subsp. lactis strain L2, present in its cell-free supernatant, were tested against pathogenic strains isolated from pig samples, such as Escherichia coli, Salmonella enterica, Streptococcus suis, Streptococcus dysgalactiae, Staphylococcus hyicus, and Enterococcus faecalis. Compounds secreted by L. lactis L2 have been shown to inhibit the growth of some pathogenic species, particularly Gram-positive bacteria, with S. suis being the most prominent. Antimicrobial peptides with a molecular size of 500-1160 Daltons were isolated from BLISs. The results highlight the potential of L. lactis BLISs and its peptides as natural antimicrobials for use in the food industry and to reduce the use of growth promoters in animal production.

Microbial community origin and fate through a rural wastewater treatment plant

Conventional wastewater treatment relies on a complex microbiota; however, much of this community is still to be characterised. To better understand the origin, dynamics and fate of bacteria within a wastewater treatment plant: untreated primary wastewater, activated sludge, and post-treatment effluent were characterised. From 3,163 Exact Sequence Variants (ESVs), 860 were annotated to species-level. In primary wastewater, 28% of ESVs were putative bacterial species previously associated with humans, 14% with animals and 5% as common to the environment. Differential abundance analysis revealed significant relative reductions in ESVs from potentially humans-associated species from primary wastewater to activated sludge, and significant increases in ESVs from species associated with nutrient cycling. Between primary wastewater and effluent, 51% of ESVs from human-associated species did not significantly differ, and species such as Bacteroides massiliensis and Bacteroides dorei increased. These findings illustrate that activated sludge increased extracellular protease and urease-producing species, ammonia and nitrite oxidizers, denitrifiers and specific phosphorus accumulators. Although many human-associated species declined, some persisted in effluent, including strains of potential health or environmental concern. Species-level microbial assessment may be useful for understanding variation in wastewater treatment efficiency as well as for monitoring the release of microbes into surface water and the wider ecosystem. This article is protected by copyright. All rights reserved.

Bacteriocin-Like Inhibitory Substance (BLIS) Activity of Enterococcus faecium DB1 Against Biofilm Formation by Clostridium perfringens

The antibiofilm effect of bacteriocin-like inhibitory substance (BLIS) from Enterococcus faecium DB1 against Clostridium perfringens was investigated in the present study. BLIS of E. faecium DB1 significantly reduced biofilm formation by C. perfringens in a dose-dependent manner for 24 and 48 h. In particular, treatment with BLIS of E. faecium DB1 significantly inhibited biofilm formation by C. perfringens on chicken meat and stainless steel coupon surfaces. Moreover, BLIS of E. faecium DB1 decreased the viability of C. perfringens biofilm and planktonic cells, indicating that the reduction of biofilm formation by C. perfringens might be achieved by killing the bacterial cells. Taken together, the present results suggest that BLIS of E. faecium DB1 can be a promising antibiofilm agent to eradicate C. perfringens.

Comparison of Sodium Nitrite and ‘Natural’ Nitrite on the Inhibition of Spore Germination and Outgrowth of Clostridium sporogenes in Low- and High-Fat Frankfurters

In the US, sodium and potassium nitrite are regulated food preservatives that prevent the germination of Clostridium spores in cured and processed meats. In recent years, the use of vegetable-derived nitrite (i.e., vegetable nitrate fermented to nitrite) has been designated as ‘natural nitrite’ to accommodate natural meats that cannot use artificial ingredients, and such meat products can be labelled as having ‘no added preservatives’. This new status and labelling allowance for microbially-modified nitrite provides for a ‘clean label’ application of nitrite against the stigma of chemical ingredients and has found increased use within the processed meat industry. The objectives of this study were to examine Clostridium sporogenes as a pathogen-surrogate challenge organism and the use of vegetable (celery) nitrite to prevent spore germination in cooked meat products. A three-strain spore crop of C. sporogenes ATCC 3584, ATCC 19404 and ATCC BAA-2695 was applied during ingredient formulation of low and high-fat hotdogs that were divided into three sub-batches (control without nitrite, hotdogs with sodium nitrite, hotdogs with celery nitrite). In both low and high-fat processes, sodium nitrite was compared to hotdogs made with comparable levels of celery nitrite (156 ppm). All treatments were performed with duplicate trial replication and triplicate sample testing within each trial. Comparisons were analyzed by repeated measures analysis of variance to determine significant difference (p < 0.05) of time course treatments. In shelf-life assays, growth was inhibited at both 5 °C and 15 °C, even if nitrite was absent; however, spore germination and growth readily occurred at 35 °C. Comparison of nitrite effects was best evaluated at 35 °C as a permissive condition to examine the effects of nitrite treatments. Celery nitrite showed no significant difference from sodium nitrite when used in both low and high-fat hotdogs, and spore outgrowth was only observed after 2–3 days at 35 °C compared to hotdogs without nitrite. Application of bacteriocin preparations in the formulation that were effective against Listeria monocytogenes, and moderately inhibitory towards the 3-strain spore mixture of C. sporogenes, were not effective in spore control in manufactured hotdogs. The nitrite validation hotdog trials described herein demonstrates that (celery or sodium) nitrite may prevent Clostridium spore germination for 24–48 h even under permissive conditions to help keep processed meat safe.

A novel in situ methodology for visual detection of Clostridium perfringens in pork harnessing saltatory rolling circle amplification

Clostridium perfringens (C. perfringens), a prolific toxin-producing anaerobe is an important foodborne pathogen with a huge public health concern. Rapid and on-site detection of C. perfringens is of specific importance in developing countries. In the present study, saltatory rolling circle amplification (SRCA) assay was developed for culture-independent, rapid and visual detection of C. perfringens and evaluated in meat with pork as a model. The specificity of the SRCA assay was ascertained by using 62 C. perfringens and 18 non- C. perfringens strains. The analytical sensitivity of the developed SRCA, conventional and real-time PCR assays were 80 fg, 800 fg and 800 fg DNA per tube, respectively. The limit of detection of the SRCA assay was 80 CFU/g of pork in the absence of enrichment and 8 CFU/g after short enrichment of 6 h. The detection limits of 80 CFU/g and 8 CFU/g of pork were attained within 120 min and 8 h, respectively. Real-world or field relevancy of the developed assay was evaluated by screening 82 raw and processed pork samples. As the developed assay is simple, user-friendly, cost-effective and sophisticated-equipment free, it would be more suitable for on-site testing of C. perfringens in foods. To our information, this is the first report to apply SRCA for the detection of C. perfringens.

Development of a novel polymerase spiral reaction (PSR) assay for rapid and visual detection of Clostridium perfringens in meat

C. perfringens is a widespread foodborne pathogen and one of the major concerns in the meat industry. There is a need for a simple, rapid and equipment free detection system for C. perfringens as conventional anaerobic culture method is labour and resource intensive. Here, we applied a novel polymerase spiral reaction phenomenon to develop and evaluate an assay for effortless and visual detection of C. perfringens in meat foods employing pork as a representative model. Specificity of the assay was determined using 51 C perfringens and 20 non- C. perfringens strains. Analytical sensitivity of the developed test was 80 fg DNA per tube indicating 100 times more sensitivity than end-point PCR assay. The detection limits were 980 CFU/g and 9.8 × 10⁴ CFU/g of pork for PSR and PCR assays, respectively. The operation time of the PSR assay including DNA extraction was 120 min. The developed PSR assay was accurate and effective in comparison to culture method, in detecting C. perfringens in 38 of 74 pork samples. Therefore the specificity, sensitivity, negative predictive value, positive predictive value and accuracy rate of the developed PSR assay were 100%. The developed PSR assay is easy to perform, rapid, affordable, permitting sophisticated-equipment free amplification and naked eye interpretation. This is the initial report in which the PSR assay was optimized for the detection of C. perfringens.

Plasma-Activated Water (PAW) as a Disinfection Technology for Bacterial Inactivation with a Focus on Fruit and Vegetables

Plasma-activated water (PAW) is generated by treating water with cold atmospheric plasma (CAP) using controllable parameters, such as plasma-forming voltage, carrier gas, temperature, pulses, or frequency as required. PAW is reported to have lower pH, higher conductivity, and higher oxygen reduction potential when compared with untreated water due to the presence of reactive species. PAW has received significant attention from researchers over the last decade due to its non-thermal and non-toxic mode of action especially for bacterial inactivation. The objective of the current review is to develop a summary of the effect of PAW on bacterial strains in foods as well as model systems such as buffers, with a specific focus on fruit and vegetables. The review elaborated the properties of PAW, the effect of various treatment parameters on its efficiency in bacterial inactivation along with its usage as a standalone technology as well as a hurdle approach with mild thermal treatments. A section highlighting different models that can be employed to generate PAW alongside a direct comparison of the PAW characteristics on the inactivation potential and the existing research gaps are also included. The mechanism of action of PAW on the bacterial cells and any reported effects on the sensory qualities and shelf life of food has been evaluated. Based on the literature, it can be concluded that PAW offers a significant potential as a non-chemical and non-thermal intervention for bacterial inactivation, especially on food. However, the applicability and usage of PAW depend on the effect of environmental and bacterial strain-based conditions and cost-effectiveness.

Changes in the fecal microbiome of the Yangtze finless porpoise during a short-term therapeutic treatment

The fecal microbiome is an integral part of aquatic mammals, like an inner organ. But we know very little about this inner organ of the threatened aquatic species, Yangtze finless porpoise (YFP). Four YFPs were placed into a purse seine for skin ulceration treatment, and this opportunity was taken to nurse the animals closer. In particular, we collected the feces of the YFPs before and after the paired healing and therapeutic treatment, along with samples of their fish diet and water habitat, to explore the changes in their fecal microbiome. Firmicutes (20.9–96.1%), Proteobacteria (3.8–78.7%), Actinobacteria (0.1–35.0%) and Tenericutes (0.8–17.1%) were the most dominant phyla present in the feces. The proportion of Proteobacteria and Actinobacteria increased after the treatment. Firmicutes showed a significant decrease, and most potential pathogens were absent, which reflected the administration of ciprofloxacin hydrochloride. Moreover, environmental shifts can also contribute to changes in the fecal microbiome. These results indicate that certain microbial interactions can be affected by environmental shifts, dietary changes and health-care treatments, which can also help maintain the internal environment of YFPs. These findings will inform the future enhanced protection and management of endangered YFPs and other vulnerable aquatic animals.

Multilocus sequence typing of Clostridium perfringens strains from neonatal calves, dairy workers and associated environment in India

Clostridium perfringens is a globally recognized zoonotic pathogen. We report isolation and genotyping of C. perfringens from neonatal calves, dairy workers and their associated environment in India. A total of 103 fecal samples from neonatal calves, 25 stool swabs from the dairy workers and 50 samples from their associated environment were collected from two dairy farms. C. perfringens was detected in 26 out of 103 (25.2%) neonatal calf samples, 7 out of 25 (28%) human stool samples and 17 out of 50 (34%) environmental samples. C. perfringens type A strains were predominant in neonatal calves (24/26; 92.3%) and associated environment (15/17; 88.2%). In contrast, strains from dairy workers mostly belonged to type F (5/7; 71.4%), which also carried the beta2 toxin gene. Seventeen strains were analyzed by multilocus sequence typing (MLST) for studying genotypic relationship along with 188 C. perfringens strains available from public databases. A total of 112 sequence types (STs) were identified from 205 C. perfringens strains analyzed. A Clonal complex (CC) represented by three STs (ST 98, ST 41 and ST 110) representing predominantly type F (18/20 strains) were mostly associated with human illnesses. Among predominant STs, ST 54 was associated with enteritis cases in foals and dogs and ST 58 associated with necrotic enteritis in poultry. Seventeen Indian strains were assigned to 13 STs. Genetic relatedness among strains of calves, dairy worker and associated environments indicate inter-host transfers and zoonotic spreads.

Toxinotyping and antimicrobial susceptibility of enterotoxigenic Clostridium perfringens isolates from mutton, beef and chicken meat

A total of 300 meat samples comprising mutton, beef, and chicken meat (n = 100) collected from either local butcher shops or large meat outlets situated at various areas of Lahore City located in Punjab province of Pakistan were tested for the isolation of Clostridium perfringens. Prevalence of the organism was highest in the chicken (6 %) followed by mutton (5 %) and beef (1 %). Contamination level was high (10/150) in the samples collected from local butcher shops in comparison to the samples collected from large meat outlets (2/150). All of the raw meat samples were negative for the presence of alpha, beta and epsilon toxins of C. perfringens as detected through ELISA. Out of a total number of 12 isolates only half were capable of producing enterotoxins when cultured in trypticase glucose yeast (TGY) broth. Toxinotyping of the isolates showed that 3 were of type A while one each of the remaining three belonged to type B, C, and D. Antibiotic susceptibility testing of the toxin producing isolates revealed that C. perfringens were susceptible to chloramphenicol, ciprofloxacin, metronidazole, and ceftriaxone. All of the other drugs were relatively less effective with a least activity of amoxicillin against the isolates.