Interactions of organic acids with Campylobacter coli from swine

Use of Organic Acids to Control Escherichia coli and Staphylococcus aureus Infection in Swine Jowl Fat

The objective of this work was to evaluate the mortality of Escherichia coli and Staphylococcus aureus inoculated in fresh swine jowls treated with different concentrations of organic acids (lactic, acetic, citric, and ascorbic) for 1, 5, and 10 min. Lactic and acetic acids showed minimum inhibitory concentrations (MICs) of 1.25 and 0.94 µL/mL against E. coli and S. aureus, respectively. Citric and ascorbic acids showed MICs of 3.75 and 7.5 µL/mL for both bacteria. In swine jowl fat, lactic acid provided mortality above 90% for both bacteria, at a concentration of 0.21% for E. coli with 5 and 10 min of exposure and 1.06% for S. aureus already with 1 min of exposure. Acetic acid showed mortality above 85% for E. coli, in the concentrations above 1.06% after 10 min, and 1.28% after 1 min of exposure. As for S. aureus, the high mortality was 73% with the maximum concentration and exposure time evaluated. Citric and ascorbic acids showed mortality of 90 and 70% for E. coli with 2.0%, respectively, and around 70% with 1.75 and 2.0% for both bacteria's. It was determined that lactic and acetic acids have good antimicrobial action against E. coli, but only lactic acid can be used at an industrial level for the microbiological control of in nature fat from swine jowls against S. aureus.

Campylobacter control strategies at postharvest level

Campylobacter is highly associated with poultry and frequently causes foodborne illness worldwide. Thus, effective control measures are necessary to reduce or prevent human infections. In this review, Campylobacter control methods applicable at postharvest level for poultry meat during production, storage, and preparation are discussed. Drying and temperature are discussed as general strategies. Traditional strategies such as steaming, freezing, sanitizing, organic acid treatment, and ultraviolet light treatment are also discussed. Recent advances in nanotechnology using antibacterial nanoparticles and natural antimicrobial agents from plants and food byproducts are also discussed. Although advances have been made and there are various methods for preventing Campylobacter contamination, it is still challenging to prevent Campylobacter contamination in raw poultry meats with current methods. In addition, some studies have shown that large strain-to-strain variation in susceptibility to these methods exists. Therefore, more effective methods or approaches need to be developed to substantially reduce human infections caused by Campylobacter.

Dietary supplementation with a novel acidifier sodium diformate improves growth performance by increasing growth-related hormones levels and prevents Salmonella enterica serovar Pullorum infection in chickens

Since the use of antibiotics as growth promoters in animal feed has been restricted or banned in several countries, finding suitable alternatives is crucial for maintaining animal health. In this study, a novel formate acidifier named sodium diformate (NaDF) was synthesized, and the effects on growth performance and the prevention effects against Salmonella enterica serovar Pullorum infections in chickens were assessed. In broilers, NaDF supplementation improved growth performance, as evidenced by increased body weights and reduced feed conversion ratios. At 38 days of age, NaDF supplementation increased the levels of growth-hormone and ghrelin in the serum, lowered pH values in the gut, improved duodenal morphology, as shown by increased villus length/crypt depth ratios. NaDF also modulated the abundance of beneficial and harmful bacteria without changing the general microbiota diversity and short-chain fatty acids levels, which would be beneficial for maintaining gut homeostasis during its use. NaDF exhibited a broad spectrum of antibacterial activity in vitro. Supplementation with NaDF effectively decreased S. Pullorum colonization in the cecum, liver and spleen in chickens, and mitigated pathological changes in the tissues. Therefore, as a novel acidifier, NaDF can improve chicken growth performance by increasing growth-related hormones levels while maintaining the diversity of gut microbiota, and also resist intestinal bacterial infection. These results provided evidences for the application of NaDF as an effective and safe animal feed in poultry farming.

Comparative Assessment of the Antibacterial and Antibiofilm Actions of Benzalkonium Chloride, Erythromycin, and L(+)-Lactic Acid against Raw Chicken Meat Campylobacter spp. Isolates

Campylobacter spp. are significant zoonotic agents, which cause annually millions of human cases of foodborne gastroenteritis worldwide. Their inclusion in biofilms on abiotic surfaces seems to play a pivotal role in their survival outside of the host, growth, and spread. To successfully mitigate the risks that arise with these bacteria, it is crucial to decrease their prevalence within the food production chain (from farm to the table), alongside the successful treatment of the resulting illness, known as campylobacteriosis. For this, the use of various antimicrobial agents remains actively in the foreground. A general-purpose biocide and cationic surfactant (benzalkonium chloride; BAC), a widely used macrolide antibiotic (erythromycin; ERY), and a naturally occurring organic acid (L(+)-lactic acid; LA) were comparatively evaluated in this work for their potential to inhibit both the planktonic and biofilm growth of 12 selected Campylobacter spp. (of which, seven were C. jejuni and five were C. coli) raw chicken meat isolates, all grown in vitro as monocultures. The inhibitory action of LA was also studied against four mixed-culture Campylobacter biofilms (each composed of three different isolates). The results showed that the individual effectiveness of the agents varied significantly depending on the isolate, growth mode (planktonic, biofilm), intercellular interactions (monocultures, mixed cultures), and the growth medium used (with special focus on blood presence). Thus, BAC exhibited minimum inhibitory concentrations (MICs), minimum bactericidal concentrations (MBCs), and minimum biofilm inhibitory concentrations (MBICs) that ranged from 0.5 to 16 μg/mL. Interestingly enough, these values varied widely from 0.25 to 1024 μg/mL for ERY. Concerning LA, the MICs, MBCs, and MBICs varied from 1024 to 4096 μg/mL, with mixed-culture biofilm formation always being more difficult to suppress when compared to biofilm monocultures. In addition, it was evident that intercellular interactions encountered within mixed-culture Campylobacter biofilms significantly influenced both the population dynamics and the tolerance of each consortium member to acid exposure. Overall, the findings of this study provide useful information on the comparative effectiveness of three well-known antimicrobial agents for the control of Campylobacter spp. under various growth modes (i.e., planktonic, biofilm, monocultures, mixed cultures) that could potentially be encountered in food production and clinical settings.

The Use of Organic Acids (Lactic and Acetic) as a Microbial Decontaminant during the Slaughter of Meat Animal Species: A Review

Wild ungulate species provide a much-needed protein source to many communities in developed and developing countries. Frequently, these game meat animals are slaughtered, and the meat is unknowingly contaminated by microorganisms and released to the unsuspecting public. This review investigates the global usage of organic acids (lactic and acetic acids) as microbial decontamination strategies during slaughter. The results show that there is a more open-minded approach to adopting possible decontamination plans as a tool to improve meat safety during slaughter. Developed countries continue to adopt these strategies, while developing countries are lagging behind. While decontamination of carcasses can lead to a reduction of microbial load on these carcasses, this strategy must not be seen as a replacement of hygiene management during the animals’ slaughter.

Murine colonization model by Campylobacter coli DSPV458

AIMS

To generate a murine experimental model of colonization by Campylobacter coli DSPV458.

METHODS AND RESULTS

Twelve adult Balb/cCmedc female mice were housed in a treated group (T-G) and a control group (C-G) for 4 weeks. Both experimental groups received antibiotics for 5 days during the first week. The T-G was administered with 6.68log₁₀ CFU of C. coli DSPV458 by oesophageal gavage. Necropsies were performed weekly to evaluate translocation and intestinal colonization in the spleen and liver and in the ileum and cecum respectively. Samples were cultured to quantify intestinal microbiota members. Faeces were cultured weekly for a C. coli DSPV458 count. Campylobacter coli DSPV458 was isolated from all the inoculated mice. The recovered level of C. coli DSPV458 was, on average, 6.9 log₁₀ CFUg^-1 , 8.0 log₁₀ CFUg^-1 and 1.6 log₁₀ CFUg^-1 in faeces, cecum and ileum respectively. Colonization by C. coli DSPV458 does not alter the normal clinical and physiological status.

CONCLUSIONS

Campylobacter coli DSPV458 does not have an invasive capacity, and the model is suitable for evaluating strategies to reduce intestinal loads.

SIGNIFICANCE AND IMPACT OF STUDY

Farm animals have an important impact on thermotolerant Campylobacter transmission to humans. Extremely few colonization models by C. coli have been reported to date. In food-producing animals, infection is mild or absent and thermotolerant Campylobacter colonize the intestines of animals. Colonization models are specific models that do not cause infection as they do not generally result in diarrhoea or other signs of disease. Therefore, this model will allow to evaluate the evolution of colonization by thermotolerant Campylobacter and the alternative tools development to antibiotics that limit their colonization in food-producing animals.

Disinfectant and antimicrobial susceptibility studies of the foodborne pathogen Campylobacter jejuni isolated from the litter of broiler chicken houses

Foodborne illness is an ongoing problem worldwide and is caused by bacteria that invade the food chain from the farm, slaughter house, restaurant or grocery, or in the home and can be controlled by strategies using biocides (antiseptics and disinfectants). Susceptibility profiles were determined for 96 Campylobacter jejuni strains obtained in 2011-2012 from broiler chicken house environments to antimicrobials and disinfectants as per the methods of the Clinical and Laboratory Standards Institute and TREK Diagnostics using CAMPY AST Campylobacter plates. Low prevalence of antimicrobial resistance was observed in C. jejuni strains to tetracycline (TET; 21.9%), ciprofloxacin (CIP; 13.5%), and nalidixic acid (NAL; 12.5%). The resistance profiles had a maximum of 3 antimicrobials, CIP-NAL-TET, with TET being the main profile observed. No cross-resistance was observed between antimicrobials and disinfectants. The C. jejuni strains (99%) were resistant to triclosan, 32% were resistant to chlorhexidine, and they all were susceptible to benzalkonium chloride. The strains had low-level minimum inhibitory concentrations (MICs) to the disinfectants P-128, Food Service Sanitizer, F-25 Sanitizer, Final Step 512 Sanitizer, OdoBan, dioctyldimethylammmonium chloride, didecyldimethylammonium chloride (C10AC), benzyldimethyldodecylammonium chloride (C12BAC), and benzyldimethyltetradecylammonium chloride (C14BAC). Intermediate MICs against DC&R, cetylpyridinium bromide hydrate, hexadecylpyridinium chloride, ethylhexadecyldimethylammonium bromide, and hexadecyltrimethylammonium bromide with elevated intermediate MICs against Tek-Trol, benzyldimethylhexadecylammonium chloride, tris(hydroxylmethyl)nitromethane (THN), and formaldehyde. The highest MIC were obtained for povidone-iodine. The components THN and the benzylammonium chlorides C12BAC and C14BAC were responsible for the inhibition by DC&R. The components C10AC and C12BAC may act synergistically causing inhibition of C. jejuni by the disinfectant P-128. The formaldehyde component in DC&R was not effective against C. jejuni compared with the ammonium chloride components. Its use in disinfectants may result in additional unnecessary chemicals in the environment. Didecyldimethylammonium chloride is the most effective ammonium chloride component against C. jejuni.

The effect of natural antimicrobials on the Campylobacter coli T6SS+/- during in vitro infection assays and on their ability to adhere to chicken skin and carcasses

Reducing the Campylobacter load on poultry carcasses represents a major tasks for the industry as its ability to reduce their presence is of major interest aiming to increase consumer safety. This study investigated the ability of a mixture of natural antimicrobials (A3001) to reduce the adherence of the T6SS^+/-C. coli isolates (NC1^hcp-, NC2 ^hcp- and NC3 ^hcp+) to chicken neck skin and whole carcasses. Overall, the antimicrobial mixture induced a significant reduction in the capability of our C. coli isolates to colonise the chicken skin (p < 0.05) and carcasses (p < 0.0001) but with a greater effect (≈3 log reduction) on the NC3 isolate. Using the HCT-8 in vitro infection model we also show that at a concentration of 0.5% A3001, the impact on the NC3 isolate is accompanied by the downregulation of the hcp gene (p = 0.0001), and indicator of the T6SS presence. The results described herein also indicated that these isolates are highly resistant to H₂O₂, up to 20 mM, suggesting a high resilience to environmental stresses. In summary our study shows that natural antimicrobials can reduce the ability of T6SS positive chicken C. coli isolates to adhere to chicken skin or to the whole carcass and to infect epithelial cells in vitro and could be considered a potential intervention at processor level.

Formic Acid as an Antimicrobial for Poultry Production: A Review

Organic acids continue to receive considerable attention as feed additives for animal production. Most of the emphasis to date has focused on food safety aspects, particularly on lowering the incidence of foodborne pathogens in poultry and other livestock. Several organic acids are currently either being examined or are already being implemented in commercial settings. Among the several organic acids that have been studied extensively, is formic acid. Formic acid has been added to poultry diets as a means to limit Salmonella spp. and other foodborne pathogens both in the feed and potentially in the gastrointestinal tract once consumed. As more becomes known about the efficacy and impact formic acid has on both the host and foodborne pathogens, it is clear that the presence of formic acid can trigger certain pathways in Salmonella spp. This response may become more complex when formic acid enters the gastrointestinal tract and interacts not only with Salmonella spp. that has colonized the gastrointestinal tract but the indigenous microbial community as well. This review will cover current findings and prospects for further research on the poultry microbiome and feeds treated with formic acid.

Short Chain Fatty Acids Commonly Produced by Gut Microbiota Influence Salmonella enterica Motility, Biofilm Formation, and Gene Expression

Short chain fatty acids (SCFAs) are commonly produced by healthy gut microbiota and they have a protective role against enteric pathogens. SCFAs also have direct antimicrobial activity against bacterial pathogens by diffusion across the bacterial membrane and reduction of intracellular pH. Due to this antimicrobial activity, SCFAs have promising applications in human health and food safety. In this study, the minimum inhibitory concentrations (MICs) of four SCFAs (acetic acid, butyric acid, propionic acid, and valeric acid) in Salmonella strains isolated from poultry were determined. The effect of subinhibitory concentrations of SCFAs in Salmonella biofilm formation, motility, and gene expression was also evaluated. Butyric acid, propionic acid, and valeric acid showed a MIC of 3750 µg/mL in all strains tested, while the MIC of acetic acid was between 1875 and 3750 µg/mL. Subinhibitory concentrations of SCFAs significantly (p < 0.05) reduced the motility of all Salmonella strains, especially in the presence of acetic acid. Biofilm formation was also significantly (p < 0.05) lower in the presence of SCFAs in some of the Salmonella strains. Salmonella strain. Salmonella Typhimurium T7 showed significant (p < 0.05) upregulation of important virulence genes, such as invA and hilA, especially in the presence of butyric acid. Therefore, SCFAs are promising substances for the inhibition of the growth of foodborne pathogens. However, it is important to avoid the use of subinhibitory concentrations that could increase the virulence of foodborne pathogen Salmonella.

Human campylobacteriosis: A public health concern of global importance

Campylobacter species are among the leading cause of bacterial foodborne and waterborne infections. In addition, Campylobacter is one of the major causative agent of bacterial gastrointestinal infections and the rise in the incidence of Campylobacter infections have been reported worldwide. Also, the emergence of some Campylobacter species as one of the main causative agent of diarrhea and the propensity of these bacteria species to resist the actions of antimicrobial agents; position them as a serious threat to the public health. This paper reviews Campylobacter pathogenicity, infections, isolation and diagnosis, their reservoirs, transmission pathways, epidemiology of Campylobacter outbreaks, prevention and treatment option, antibiotics resistance and control of antibiotics use.

Biocide Potentiation Using Cinnamic Phytochemicals and Derivatives

Surface disinfection is of utmost importance in the prevention of bacterial infections. This study aims to assess the ability of ten phytochemicals and related derivatives as potentiators of two commonly used biocides-cetyltrimethylammonium bromide (CTAB) and lactic acid (LA). LA in combination with cinnamic, hydrocinnamic, α-methylcinnamic, and α-fluorocinnamic acids had a factional inhibitory concentration index (FICI) ≤ 1 for Escherichia coli and Staphylococcus aureus. Several phytochemicals/derivatives in combination with biocides improved the biocidal efficacy against early sessile bacteria. The most effective combination was LA with allyl cinnamate (2.98 ± 0.76 log CFU.cm^-2 reduction) against E. coli. The combination with CTAB was successful for most phytochemicals/derivatives with a maximum bactericidal efficacy against sessile E. coli when combined with allyl cinnamate (2.20 ± 0.07 log CFU.cm^-2 reduction) and for S. aureus when combined with α-methylcinnamic acid (1.68 ± 0.30 log CFU.cm^-2 reduction). This study highlights the potential of phytochemicals and their derivatives to be used in biocide formulations.

In Vitro Antimicrobial Activities of Organic Acids and Their Derivatives on Several Species of Gram-Negative and Gram-Positive Bacteria

The objective of this study was to determine the in vitro antimicrobial activity of several organic acids and their derivatives against Gram-positive (G+) and Gram-negative (G-) bacteria. Butyric acid, valeric acid, monopropionin, monobutyrin, monovalerin, monolaurin, sodium formate, and ProPhorce-a mixture of sodium formate and formic acid (40:60 w/v)-were tested at 8 to 16 concentrations from 10 to 50,000 mg/L. The tested bacteria included G- bacteria (Escherichia coli, Salmonella enterica Typhimurium, and Campylobacter jejuni) and G+ bacteria (Enterococcus faecalis, Clostridium perfringens, Streptococcus pneumoniae, and Streptococcus suis). Antimicrobial activity was expressed as minimum inhibitory concentration (MIC) of tested compounds that prevented growth of tested bacteria in treated culture broth. The MICs of butyric acid, valeric acid, and ProPhorce varied among bacterial strains with the lowest MIC of 500-1000 mg/L on two strains of Campylobacter. Sodium formate at highest tested concentrations (20,000 mg/L) did not inhibit the growth of Escherichia coli, Salmonella Typhimurium, and Enterococcus faecalis, but sodium formate inhibited the growth of other tested bacteria with MIC values from 2000 to 18,800 mg/L. The MIC values of monovalerin, monolaurin, and monobutyrin ranged from 2500 to 15,000 mg/L in the majority of bacterial strains. Monopropionin did not inhibit the growth of all tested bacteria, with the exception that the MIC of monopropionin was 11,300 mg/L on Clostridia perfringens. Monolaurin strongly inhibited G+ bacteria, with the MIC value of 10 mg/L against Streptococcus pneumoniae. The MIC tests indicated that organic acids and their derivatives exhibit promising antimicrobial effects in vitro against G- and G+ bacteria that are resistant to antimicrobial drugs. The acid forms had stronger in vitro antimicrobial activities than ester forms, except that the medium chain fatty acid ester monolaurin exhibited strong inhibitory effects on G+ bacteria.

Inhibition and Interactions of Campylobacter jejuni from Broiler Chicken Houses with Organic Acids

Campylobacter jejuni is a bacterium that causes major diarrheal disease worldwide and is also one of the top five foodborne pathogens encountered in the United States. Poultry is a major source of C. jejuni, and a high-risk factor for contracting campylobacteriosis. Organic acids are used in the United States during food animal processing for removal of bacterial contamination from animal carcasses. Six organic acids were evaluated in inhibition studies of 96 C. jejuni strains obtained from shoe covers used in broiler chicken houses at different poultry farms in several states by determining the susceptibilities of the C. jejuni strains, along with the pH values at the molar minimum inhibitory concentrations (MICMs). The undissociated and dissociated organic acid concentrations were calculated at the MICMs with the Henderson-Hasselbalch equation. The results for the 96 C. jejuni strains were treated similarly for each different organic acid. Campylobacter jejuni inhibition did correlate with the dissociated organic acids, but did not correlate with pH or with the undissociated organic acids. When the concentrations of dissociated organic acids decreased, the C. jejuni strains were not disinfected. A carcass wash using organic acids should have the concentration of dissociated acid species carefully controlled. It is suggested to maintain a dissociated acid concentration for propionic, l-lactic, formic, citric, butyric, and acetic acids at 24, 40, 36, 21, 23, and 25 mM, respectively, and at these dissociated organic acid levels an acid wash would be expected to remove or inhibit 97% or more of the C. jejuni bacteria studied here. However, studies must be undertaken to confirm that the suggested concentrations of dissociated organic acids are adequate to remove C. jejuni bacteria in the field vs. the laboratory. Due to propionate, l-lactate, formate, butyrate, and acetate being utilized by C. jejuni, these organic acids may not be appropriate for use as a carcass wash to remove C. jejuni surface contamination. Of all tested organic acids, dissociated citric acid was the most efficient at inhibiting C. jejuni.

Disinfectant and Antimicrobial Susceptibility Profiles of Campylobacter coli Isolated in 1998 to 1999 and 2015 from Swine and Commercial Pork Chops

Susceptibility profiles were determined for 111 Campylobacter coli strains obtained in 1998 to 1999 and 2015 from market age pigs and pork chops against 22 disinfectants and 9 antimicrobials. Resistance to tetracycline (TET) was observed in 44.4% of 1998 to 1999 strains, and the antibiotic resistance profile was TET. But strains obtained in 2015 from swine and retail pork chops had 75% TET resistance and the antibiotic resistance profile was TET, followed by azithromycin-erythromycin-TET-telithromycin-clindamycin. Antimicrobial resistance increased in 2015 strains. All strains were resistant to triclosan, and 84.1% and 95.8% of strains in 1998 to 1999 and 2015, respectively, were chlorhexidine resistant. All strains were susceptible to benzalkonium chloride. There was a shift toward higher susceptibility to chlorhexidine, triclosan, P-128, OdoBan, CPB, and CPC in 2015 swine and pork chop strains compared with 1998 to 1999 strains. The disinfectants Tek-Trol and providone-iodine, tris(hydroxylmethyl)nitromethane (THN) and formaldehyde demonstrated the highest susceptibilities. Didecyldimethylammonium chloride (C10AC) appeared to be about equally effective as benzyldimethyltetradecylammonium chloride (C14BAC) for inhibiting C. coli, and both were more effective than C8AC and C12BAC, but C16BAC was not efficient at inhibiting C. coli. The BACs, C12BAC and C14BAC, were the most effective ingredients in DC&R. Also, C12BAC and C14BAC, or these two in synergy with C10AC were responsible for inhibition of C. coli at high P-128 MICs. No cross-resistance was observed between antibiotics and disinfectants. The continued use of THN and formaldehyde in DC&R should be evaluated since these components are not effective, and their inclusion adds unwanted chemicals in the environment. PRACTICAL APPLICATION: Campylobacter species cause diarrheal disease throughout the world. Disinfectants are often used on the farm, in veterinary medicine, by the food processing industry, in restaurants, and in consumer's homes. Limited information is available in the literature showing how disinfectants or disinfectant components may affect the many different foodborne pathogens, and, specifically, Campylobacter coli studied here. The knowledge generated in this study concerning the interactions of a broad array of disinfectants against C. coli may well affect the types of disinfectants and disinfectant formulations allowable for use by medical personnel, producers, food processors, restaurants, and consumers.

Interactions of organic acids with vancomycin-resistant Enterococcus faecium isolated from community wastewater in Texas

AIMS

Investigate the interactions of organic acids (OAs), acetic, butyric, citric, formic, lactic and propionic acid against 50 Gram-positive vancomycin-resistant Enterococcus faecium (VRE) strains to determine whether pH, undissociated or dissociated acid forms correlate with bacterial inhibition.

METHODS AND RESULTS

Concentrations of undissociated and dissociated OAs at the molar minimum inhibitory concentrations (MIC_M s) of the VRE were calculated using the Henderson-Hasselbalch equation. The pH at the MIC_M s of all VRE strains against acetic, butyric, formic and propionic acids was similar, 4·66 ± 0·07, but there was a 1·1 pH unit difference for all six OAs. Inhibition of VRE by all six OAs did not appear to be solely dependent on pH or on the undissociated OA species. The inhibition of VRE by all six dissociated acids was within Δ = 3·1 mmol l^-1 .

CONCLUSIONS

Vancomycin-resistant Enterococcus faecium inhibition correlated with the dissociated OA species. A small decrease in the concentration of the dissociated OAs from optimum may result in allowing VRE strains to escape disinfection.

SIGNIFICANCE AND IMPACT OF THE STUDY

When an OA is used to disinfect VRE strains, the concentration of the dissociated OA should be carefully controlled. A concentration of at least 20 mmol l^-1 dissociated OA should be maintained when disinfecting VRE.