Enterica Ser Research Articles

Validation of the Level 2 Modification for the Neogen® Molecular Detection Assay 2 - Salmonella Enteritidis/Salmonella Typhimurium Method for Detection of the Monophasic Variant Salmonella enterica 1,4,[5],12:-:1,2.

The Neogen® Molecular Detection Assay 2-Salmonella Enteritidis/Salmonella Typhimurium (MDA2-SE/ST) method, Performance Tested Method SM (PTM) 122302, is a nucleic acid amplification test for specific detection of Salmonella enterica ser. Enteritidis (SE) and Salmonella enterica ser. Typhimurium (ST), including the ST monophasic variant Salmonella enterica 1,4,[5],12:i:-, in select poultry samples. Results for SE and ST are generated separately. The objective of the study was to validate the MDA2-SE/ST method for detection of an additional monophasic variant of ST, S. enterica 1,4,[5],12:-:1,2. A single strain of S. enterica 1,4,[5],12:-:1,2 was tested as part of a seven-strain inclusivity/exclusivity test panel. Strains were tested after growth in two enrichment media used in the method, buffered peptone water (BPW) and buffered peptone water-ISO formulation (BPW-ISO), and at two incubation temperatures, 35 ± 2 °C and 41.5 ± 1 °C. S. enterica 1,4,[5],12:-:1,2 produced positive results in the ST assay and negative results in the SE assay in both enrichment media and at both incubation temperatures. Results for the other six test strains were as expected under all conditions. The MDA2-SE/ST method can detect the monophasic variant S. enterica 1,4,[5],12:-:1,2 as well as S. enterica ser. Typhimurium and the monophasic variant S. enterica 1,4,[5],12:i:-. The MDA2-SE/ST method maintains inclusiveness for S. enterica ser. Typhimurium despite flagellar antigen variation. The data were reviewed by the AOAC PTM Program and approval was granted for modification of the MDA2-SE/ST method, PTM 122302.

Molecular Patterns and Antimicrobial Resistance Characterization of Salmonella enterica Non-Typhoidal from Human, Food, and Environment Samples Isolated in Luanda, Angola

The aim of this study was to characterize the antimicrobial resistance phenotype and genotype of non-typhoidal Salmonella spp. isolated in Luanda, Angola. Between 2013 and 2015, human clinical samples, food, and environmental samples (n = 290) were collected at different regions of Luanda city and screened for the presence of Salmonella spp. Bacterial isolates were preliminarily identified using the API 20E Kit, and their identification was confirmed using PCR and serotyping. All Salmonella spp. isolates were tested by minimum inhibitory concentration against 19 antimicrobials. The isolates were also screened using PCR for the presence of resistance genes (blaOXA-1, blaSHV, blaTEM, sul1, sul2, sul3, qnrA, qnrB, qnrS, qnrC, qnrD, aac(6′)-Ib, dfrIa [targeting dfrA1, dfrA5, dfrA15, dfrA15b, dfrA16, dfrA16b] and dfrA12, cmlA, and floR) and typed using pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). Salmonella enterica non-typhoidal was detected in 21.3% of the clinical samples (n = 32/150), 11.1% of the food samples (n = 10/90), and 26% of the environmental samples (n = 13/50). Serotyping revealed that the monophasic variant of Salmonella Typhimurium (Salmonella enterica serovar 4,[5],12:i:-) was detected in 38.1% of the samples. Moreover, serovar Salmonella Enteritidis was the second most frequent. Only 7.3% of the isolates were resistant to at least one antimicrobial. Furthermore, isolates from different origins (clinical, environmental, and food) were associated with the same lineages, Salmonella Enteritidis ST11 and S. enterica ser. Typhimurium ST313. The detection of S. enterica serovar 4,[5],12:i:- in different settings reinforces the need for a One Health approach to control this zoonosis in Angola.

Development of Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Pseudomonas aeruginosa multi-species in vitro dry surface biofilm models: Insights into resilience and persistence in low-moisture environments

Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Pseudomonas aeruginosa can persist as dry surface biofilms (DSB) and survive desiccation for prolonged periods of time. This could serve as potential sources of contamination in low-moisture food (LMF) processing environments. The objectives of this study were to develop in vitro mono-and mix-culture DSB models to better understand pathogen survival under dehydrated conditions as DSB. Mono-and mix-culture wet surface biofilms (WSB) of S. enterica ser. Typhimurium ATCC 14028, L. monocytogenes FSL R8-5318, and P. aeruginosa ATCC 15442 were developed following EPA MLB SOP MB-19 protocol on borosilicate glass coupons using a CDC® biofilm reactor. WSB were harvested and dried for 24, 48, and 72 h at 21 °C to form DSB. Mean log10 CFU/cm2 were calculated at each desiccation time point and compared to control (WSB) using LSM of PROC GLM to fit linear models (P = 0.05). Approximately 8.8 ± 1.7, 7.1 ± 1.1, 6.9 ± 0.6, and 6.3 ± 0.8 mean log10 CFU/coupon were recovered from mono-culture Salmonella DSB at 0, 24, 48, and 72 h, respectively. Overall, Salmonella mean log10 densities were limited when co-cultured with P. aeruginosa although there were no significant differences in Salmonella density over desiccation time points. Mean log10 CFU/coupon for L. monocytogenes monoculture DSB were comparatively lower i.e., 5.7 ± 0.4 (0 h), 3.8 ± 0.1 (24 h), and 3.4 ± 0.6 (48 h), and 2.6 ± 0.3 (72 h). However, when co-cultured with P. aeruginosa, L. monocytogenes exhibited consistently higher cell densities 6.7 ± 0.4, 6.0 ± 0.9, 5.6 ± 0.04, and 4.9 ± 0.6, at 0, 24, 48, and 72 h, respectively. On average, P. aeruginosa consistently exceeded six log10 at each desiccation time point in co-culture. Confocal laser scanning microscopy (CLSM) images confirmed biofilm development and persistence over time in mono and mixed cultures. This work provides foundational evidence toward better understanding pathogen survival under dehydrated conditions, interactions between different pathogens within desiccated biofilms, and their respective survival rates. Additionally, these data provide quantitative assessment of bacterial load within DSB under high-risk scenarios for LMFs. These models provide opportunities to explore targeted mitigation strategies, including efficacy of dry sanitation practices, to prevent the formation or remove DSB in LMF processing environments.

Antibacterial activity of lactic acid bacteria from black soldier fly (Hermetia illucens) larvae fed with empty fruit bunch and tofu waste

Antibiotic Growth Promoters (AGP) are prohibited for use in livestock due to their detrimental effects on consumer safety and livestock productivity. Probiotics are an alternative to AGP because they offer microorganisms that are beneficial to the livestock health. In this investigation, Lactic acid bacteria (LAB) from the Black Soldier Fly (BSF) larvae’s will be isolated, tested for their antimicrobial activities and molecularly identified using 16S rRNA gene with Polymerase Chain Reaction (PCR) technique. The larvae are fed with empty fruit bunch and tofu wastes as a source of prebiotics to the indigenous LAB. The LAB isolates were enumerated and morpho-biochemically characterized. Disk diffusion method was used to determine the antibacterial efficacy of LAB isolates against pathogenic bacteria, such as Salmonella enterica serotype Pullorum, Salmonella enterica serotype Typhimurium ATCC® 14028, and Escherichia coli ATCC® 8739. Nine bacterial isolates were purified from a population density of log 6 Colony-forming unit (CFU)/mL on de Man Rogosa Sharp (MRS) agar. Four LAB isolates were confirmed through (-) catalase activity and acids production (homofermentative). Two LAB isolates namely 5P3i3 and 5P3i5 were designated as the most potential strains against three pathogenic bacteria with the strongest inhibitory activities against E. coli, followed by S. enterica ser. Typhimurium and S. enterica ser. Pullorum. By using 16S rRNA gene sequencing, the two LAB isolates were assigned to Lactiplantibacillus pentosus and submitted to GenBank as L. pentosus strain 5P3i3 (OP445834.1) and L. pentosus strain 5P3i5 (OP445835.1). The results of this study will be further investigated with the characterization of potential isolates as probiotic candidates to be supplemented in poultry.

The Primary Mode of Action of Lippia graveolens Essential Oil on Salmonella enterica subsp. Enterica Serovar Typhimurium.

Essential oils are known to exhibit diverse antimicrobial properties, showing their value as a natural resource. Our work aimed to investigate the primary mode of action of Cuban Lippia graveolens (Kunth) essential oil (EO) against Salmonella enterica subsp. enterica serovar Typhimurium (S. enterica ser. Typhimurium). We assessed cell integrity through various assays, including time-kill bacteriolysis, loss of cell material with absorption at 260 and 280 nm, total protein leakage, and transmission electron microscopy (TEM). The impact of L. graveolens EO on membrane depolarization was monitored and levels of intracellular and extracellular ATP were measured by fluorescence intensity. The minimum inhibitory and bactericidal concentrations (MIC and MBC) of L. graveolens EO were 0.4 and 0.8 mg/mL, respectively. This EO exhibited notable bactericidal effects on treated cells within 15 min without lysis or leakage of cellular material. TEM showed distinct alterations in cellular ultrastructure, including membrane shrinkage and cytoplasmic content redistribution. We also observed disruption of the membrane potential along with reduced intracellular and extracellular ATP concentrations. These findings show that L. graveolens EO induces the death of S. enterica ser. Typhimurium, important information that can be used to combat this foodborne disease-causing agent.

Microflora, Contents of Polyamines, Biogenic Amines, and TVB-N in Bovine Offal and Game Meat for the Raw-Feeding of Adult Dogs.

Microflora and contents of biogenic amines/polyamines and total volatile basic nitrogen (TVB-N) in 99 samples of bovine offal (red offal, n = 41 and other offal and mixes, n = 45) and wild game meat (n = 13) for raw meat-based diets (RMBD) for dogs were analyzed. Samples were bought in 11 local pet food shops and in one game-handling establishment in Austria (Lower Austria, Styria, and Vienna) in September and October 2022. Median contents (first and third quartiles in brackets) of cadaverine, histamine, tyramine, spermidine, and spermine were 20.7 [16.7; 28.6]; 25.4 [17.1; 47.2]; 18.9 [13.6; 38.9]; 15.2 [11.2; 21.2]; and 41.9 [<limit of detection; 64.5] mg/kg wet weight, respectively. The sum of putrescine + cadaverine + histamine + tyramine was >50 mg/kg in 85.9% of samples, indicating the use of low-quality ingredients or inappropriate storage conditions. However, only 10.1% of samples were determined to be not compliant with a maximum amine content proposed for pet food. Median contents of the total aerobic bacteria counts (TACs), Pseudomonas, and Enterobacteriaceae were 7.4 [6.4; 8.0]; 6.5 [5.5; 7.7]; and 4.8 [3.9; 5.6] log CFU/g, respectively, with significantly lower counts in red offal RMBD (p < 0.05). TVB-N exceeded 150 mg/kg in 87.9% of samples. The TACs and Enterobacteriaceae numbers in red offal RMBD were comparable to those in food-grade red offal after 6 days of aerobic storage at 7 °C, i.e., temperatures higher than required for food-grade offal, but acceptable for animal by-products intended for RMBD production. In 80.8% of samples, numbers of Enterobacteriaceae exceeded the EU legal limit. From 12 of these samples, Salmonellae was able to be isolated, with counts from 0.03 MPN/g to 110 MPN/g. Salmonella enterica ser. Montevideo (n = 3), and S. enterica ser. Give and S. enterica ssp. Diarizonae (n = 2 each) were the most frequently isolated, while Listeria monocytogenes was rarely recovered (2%). Whilst exposure of humans handling such pet food can be reduced by hygiene precautions, the risk remains that dogs can acquire a feed-borne salmonellosis and shed the pathogen.

Multiplex touchdown Polymerase Chain Reaction for rapid detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in food

The Salmonella outbreak is one of the leading foodborne diseases in the world with increasing cases being reported annually. However, the current methods for Salmonella detection in foods are outdated, laborious and time-consuming. This necessitated developing a technique that is rapid for Salmonella detection in foods. Thus, the current study aimed to develop a multiplex touchdown PCR (m-TdPCR) protocol for rapid and simultaneous detection of Salmonella enterica subsp. enterica serovars Enteritidis and Typhimurium in foods. A two-phase m-TdPCR protocol was developed and optimized with primer pairs targeting the Salmonella enterica subsp. enterica (ST11/ST15-0.15 µM), serovars Enteritidis (sdfI gene-1.2 µM), Typhimurium (fliC gene-1.5 µM) and an internal amplification control (16S rRNA-0.08 µM). It was found that the m-TdPCR protocol is highly sensitive detecting up to 1 ng of Salmonella DNA and its specificity was verified using the in-silico method. Furthermore, the developed m-TdPCR shows no non-specific PCR amplicons and is able to detect both S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in real-time when tested against the artificially contaminated food samples at up to 10-3 dilutions. Therefore, the validated m-TdPCR protocol in this study can be used as a tool for rapid detection of S. enterica ser. Enteritidis and S. enterica ser. Typhimurium in food samples and this may significantly reduce any related foodborne incidences in future.

Synthesis, characterization, anticancer activity, and molecular docking study of some metal complexes with a new Schiff base ligand

2-((E)-((4-(((E)-4-methoxybenzylidene)amino)phenyl)imino)methyl)naphthalen-1-ol, a new Schiff base ligand, was made and then metalated with number of metal ions. The compounds were characterized by various techniques. The result confirmed that the ligand coordinated with the metals in a bidentate nature, through azomethine nitrogen and phenolic oxygen atom; and gave an octahedral geometry. The XRD patterns of the ligand and complexes of Fe(III), Co(III), and Zn(II) have a crystalline nature, while the Ni(II), and Cu(II) complexes have an amorphous structure. The antibacterial and antifungal effects were investigated. It was observed that the Zn(II) and Fe(III) complexes had the highest activity among the compounds against S. enterica ser. typhi and C. albicans, respectively. The IC50 values demonstrated that the Ni(II) complex displayed the highest activity against A549, HepG-2, and PC-3 cancer cell lines. Furthermore, molecular docking simulation revealed that the Zn(II), Co(III), and Ni(II) complexes were shown to have a high binding affinity with the active sites targets of S. enterica ser. typhi bacteria and C. albicans fungi strains, and the active sites of three targets in the cancer cell lines A549, HepG-2, and PC-3, respectively.

The magnitude of heterogeneity in individual-cell growth dynamics is an inherent characteristic of Salmonella enterica ser. Typhimurium strains

Individual-cell heterogeneity is a major source of variability in biological systems affecting importantly, among others, microbial behavior. Characterization of cell populations of pathogenic bacterial strains in their entirety, ignoring the phenotypic variability of single cells, may result in erroneous safety risk estimates. The objective of the present study was the evaluation and comparison of the heterogeneity in the individual-cell growth dynamics of different strains of Salmonella enterica. The stochasticity in the growth of single cells of five S. enterica ser. Typhimurium strains was quantitatively described using time-lapse microscopy, and the existence of a strain effect was statistically assessed. In total, 831 growing microcolonies originating from single cells were monitored and analyzed, and the growth kinetic parameters of lag time (λ) and maximum specific growth rate (μmax) for each one of them were estimated. An extensive heterogeneity in individual-cell growth kinetics was recorded, while significant inter-strain differences in their heterogeneity were evident based on simultaneous Bonferroni confidence intervals and Levene’s tests. The Logistic and LogLogistic probability distribution provided the best fitting for μmax and λ data, respectively for all the tested strains. The strain effect on the above distributions was also demonstrated with pairwise comparisons of the decile differences. The impact of strain-dependent heterogeneity on microbial growth was visualized by comparing stochastic growth curves of different strains using Monte Carlo simulation. In conclusion, the individual-cell growth dynamics of S. enterica are heterogeneous, with the magnitude of the observed heterogeneity appearing to be an inherent characteristic of bacterial strains.

In vitro antimicrobial appraisal of the potentials of Morinda lucida against some selected bacteria

The bioactive compounds from plant extract represent a potent alternative to combating the increasing antimicrobial resistance (AMR) to synthetic drugs. This study aimed to investigate the phytochemical, and antibacterial activities of Morinda lucida. Leaves of M. lucida was extracted successively using n-hexane, acetone, methanol and distilled water. The crude plant extracts were evaluated for their antibacterial activity against pathogens found in food and other sources such as Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella enterica serovar Typhi, Escherichia coli, and Klebsiella spp. using the agar well diffusion technique. Minimum inhibitory concentration (MIC) was carried out using the microbroth dilution technique. The phytochemical analysis showed the presence of alkaloids and sterols in all extracts. Flavonoid was only present in the n-Hexane extract. The result showed that n-Hexane extract had the widest zone of inhibition against P. aeruginosa - 13.67 mm (12.5 mg/mL MIC), B. subtilis - 15 mm (12.5 mg/mL MIC), while acetone extract was most active against S. enterica ser. Typhi - 24.67 mm (6.25 mg/mL MIC), S. aureus - 24.83 mm (3.13 mg/mL MIC), E. coli - 13.33 mm (1.56 mg/mL MIC) and Klebsiella spp. - 18.33 mm (12.5 mg/mL MIC). These findings indicated that n-Hexane and acetone extract of M. lucida exhibited significant antimicrobial activity. Therefore, further research should be carried out to isolate the bioactive compounds with potentials in developing new drug leads against drug-resistant microbial strains.

Nanoparticle-Enabled Combination Therapy Showed Superior Activity against Multi-Drug Resistant Bacterial Pathogens in Comparison to Free Drugs.

The emergence of multidrug-resistant (MDR) bacterial pathogens in farm animals and their zoonotic spread is a concern to both animal agriculture and public health. Apart from antimicrobial resistance (AMR), bacterial pathogens from the genera of Salmonella and Staphylococcus take refuge inside host cells, thereby demanding intervention strategies that can eliminate intracellular MDR pathogens. In this study, seven clinical isolates of Salmonella and Staphylococcus from swine farms were characterized for antibiotic (n = 24) resistance, resistance mechanisms, and virulence characteristics. All isolates showed resistance to one or more antibiotics and S. enterica ser. Typhimurium isolate had the highest resistance to the panel of antibiotics tested. Major resistance mechanisms identified were efflux pump and beta-lactamase enzyme activities. Staphylococcus isolates showed complete hemolysis and strong biofilm formation, while Salmonella isolates caused partial hemolysis, but showed no or weak biofilm formation. MDR isolates of S. aureus M12 and S. enterica ser. Typhimurium bacteria were subsequently tested against combinations of antibiotics and potentiating adjuvants for improved antibacterial efficacy using a checkerboard assay, and their fractional inhibitory concentration index (FICI) was calculated. A combination of chitosan and silica nanoparticles containing tetracycline (TET) and efflux pump inhibitor chlorpromazine (CPZ), respectively, was characterized for physicochemical properties and effectiveness against MDR Salmonella enterica ser. Typhimurium isolate. This combination of nano-encapsulated drugs improved the antibacterial efficacy by inhibiting AMR mechanisms (efflux activity, beta-lactamase enzyme activity, and hydrogen sulfide (H2S) production) and reducing intracellular pathogen load by 83.02 ± 14.35%. In conclusion, this study sheds light on the promising applicability of nanoparticle-enabled combination therapy to combat multidrug-resistant pathogens encountered in animal agriculture.

A New Vaccination Method Based on Phage NgoΦ6 and Its Phagemid Derivatives.

Phagemid particles based on the Neisseria gonorrhoeae filamentous phage NgoΦ6 were used as a vaccine delivery system. We demonstrate that the host proteins incorporated into/associated with these particles can be encoded by chromosomal genes of the host bacterium or from plasmids able to replicate as an autonomous entity in the phagemid host. Phagemid particles were prepared from three types of cells, namely, Salmonella enterica ser. Typhimurium [pBSKS::Φ6fm(ST)] containing phagemid genome as an autonomous plasmid, Haemophilus influenzae Rd containing phagemid [pBSKS::Φ6fm(Hin)] integrated into the chromosome, and S. enterica ser. Typhimurium [pMPMT6::Φ6fm(ST)] containing an additional plasmid, pE1 HCV, encoding the Hepatitis C virus envelope glycoprotein E1. Approximately 200 μg of purified phage particles was used to immunize rabbits. The phagemid particles prepared from these three strains all elicited a large amount of IgG antibodies that were able to recognize bacterial host cells and proteins, as determined by ELISA and FACS analysis. The amount of specific anti-S. enterica ser. Typhimurium, anti-H. influenzae, and anti-E1 HCV antibodies elicited by vaccination was 170 μg/ml for anti-Salmonella, 80 μg/ml for anti-H. influenzae, and 65 μg/ml for anti-E1 HCV. Taken in toto, these data suggest that classical phage display methods have underestimated the potential for filamentous phage as a novel immunogen delivery system.

Inactivation kinetics of Salmonella enterica serovar Typhimurium NCTC 12023 in Chokanan mango (Mangifera indica L.) fruit juice by aqueous ozone treatment

Food processing industries worldwide focus on maintaining and enhancing food quality and security, particularly microbial food safety, to fulfil customer requirements. This study examined the efficacy of aqueous ozone on the inactivation of Salmonella enterica serovar Typhimurium NCTC 12023 in Chokanan mango juice (MJ) diluted with distilled water (DW) ratios (100MJ:0DW, 75MJ:25DW, and 50MJ:50DW). The inoculated MJ samples were treated at 10, 20, 30, and 40 mins with ozone doses 0.33, 0.67, 1.00, and 1.33 mg/mL. The results showed that the Bx values and mango pulp presence in the various MJ samples interfered with the S. enterica ser. Typhimurium disinfection activity by ozone. The S. enterica ser. Typhimurium inactivation and the survival curves’ concavity are more reliably measured in the kinetic Weibull model. Validation of the Weibull model produced coefficient determination (R 2 ) of 0.94–0.99, RSME of 0.1 to 0.4, bias and accuracy factor of 0.7 to 1.4, and shape parameter p&lt;1. A fast inactivation rate for 5-log reduction of S. enterica ser. Typhimurium was observed in 50MJ:50DW sample (24.82 mins, 0.82 mg/mL) and in 75MJ:25DW sample (28.39 mins, 0.95 mg/mL), respectively. However, in the 100MJ:0DW sample, the 5-log reduction was achieved at 36.39 min with an ozone dose of 1.20 mg/mL. Nevertheless, this study’s ozone dose range from 0.33 mg/mL to 1.33 mg/mL with a treatment time of 10 to 40 mins has proven to lower and achieved a 5-log reduction of S. enterica ser. Typhimurium in all MJ samples

Anti-Adhesion and Antibiofilm Activity of Eruca sativa Miller Extract Targeting Cell Adhesion Proteins of Food-Borne Bacteria as a Potential Mechanism: Combined In Vitro-In Silico Approach.

Bacterial cells have the ability to form biofilm onto the surfaces of food matrixes and on food processing equipment, leading to a source of food contamination posing serious health implications. Therefore, our study aimed to determine the effect of Eruca sativa Miller (E. sativa) crude extract against biofilms of food-borne bacteria along with in silico approaches to investigate adhesion proteins responsible for biofilm activity against the identified phytochemicals. The antibacterial potential of crude extract was evaluated using agar well diffusion technique and combinations of light and scanning electron microscopy to assess the efficacy of crude extract against the developed biofilms. Our results showed that crude extract of E. sativa was active against all tested food-borne bacteria, exhibiting a rapid kinetics of killing bacteria in a time-dependent manner. MIC and MBC values of E. sativa crude extract were found to be ranging from 125 to 500 µg/mL and 250 to 1000 µg/mL respectively. Furthermore, inhibition of developed biofilm by E sativa was found to be ranging from 58.68% to 73.45% for all the tested strains. The crude extract also reduced the viability of bacterial cells within biofilms and amount of EPS (ranging 59.73–82.77%) in the biofilm matrix. Additionally, the microscopic images also revealed significant disruption in the structure of biofilms. A molecular docking analysis of E. sativa phytochemicals showed interaction with active site of adhesion proteins Sortase A, EspA, OprD, and type IV b pilin of S. aureus, E. coli, P. aeruginosa, and S. enterica ser. typhi, respectively. Thus, our findings represent the first demonstration of E. sativa crude extract’s bioactivity and potency against food-borne bacteria in their planktonic forms, as well as against the developed biofilms. Therefore, a possible mechanistic approach for inhibition of biofilm via targeting adhesion proteins can be explored further to target biofilm producing food-borne bacterial pathogens.

Effects of the combination of some essential oils with methylparaben and sodium metabisulfite against pathogenic foodborne bacteria

In this work, the antimicrobial and antioxidant activity of some essential oils (EOs) and their synergistic effects with synthetic preservatives against foodborne pathogenic bacteria were evaluated. Nine EOs were screened against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Salmonella enterica serotype Typhi, and six of these were associated with methylparaben (MTP) and sodium metabisulfite (MTBS). Essential oils of cinnamon and oregano showed potential antibacterial activity. The combinations of cinnamon + MTP, coriander + MTP, and oregano + MTP, showed synergism against S. enterica ser. Typhi, E. coli, and S. aureus, respectively. Clove oils exhibited higher radical scavenging activity against DPPH. Moreover, clove leaves + MTP presented a synergistic antimicrobial interaction against E. coli and S. enterica ser. Typhi. These findings showed a reduction in the minimal inhibitory concentration (MIC) of the synthetic preservative with a low concentration of EOs, highlighting an alternative source as preservatives in embedded foods and derivatives for the food industry. Novelty impact statement The use of essential oils in combination with the synthetic preservative methylparaben (MTP) promoted synergistic antimicrobial effects against foodborne bacteria. The clove leaf oil showed synergism with MTP against Gram-negative bacteria (FICI = 0.49) and high antioxidant activity (IC50 = 8.06 μg/ml), and this can be used as an alternative source for delaying the oxidative process and for the preservation of food products.

Prevalence and antimicrobial resistance of Salmonella spp. isolated from free-ranging wild boars in the State of São Paulo, Brazil

ABSTRACT: European wild boars (Sus scrofa) are considered exotic invasive species worldwide. Invasions of wild boars are a growing public health concern, as wild boars may represent an important reservoir of zoonotic pathogens, including bacteria of the genus Salmonella. The aim of this study was to determine the prevalence and serovars of Salmonella spp. in free-ranging wild boars legally hunted in the state of São Paulo, Brazil, and the susceptibility of those Salmonella spp. to antimicrobials. Fecal samples and mesenteric lymph nodes were acquired from 63 wild boars. The prevalence of Salmonella spp. in free-ranging wild boars was 9.5 % (6/63; confidence interval: 4.4 % - 19.2 %). Six serovars were isolated: S. enterica subsp. enterica ser. 4,5,12:-:1,2, S. enterica ser. Cerro, S. enterica ser. Madelia, S. enterica ser. Typhimurium, S. enterica ser. I (4,5,12:i:-) and S. enterica ser. Muenster. Analysis of antimicrobial resistance of Salmonella spp. showed that the majority of serovars were fully susceptible to the tested antimicrobials. Only S. enterica ser. Typhimurium and S. enterica ser. Muenster showed a resistance pattern to at least one antimicrobial analyzed. To our knowledge, this study is the first report the prevalence and serovars of Salmonella spp. in free-ranging wild boars in the State of São Paulo, Brazil. Results indicate a low prevalence with variability of Salmonella serovars, with some pattern of antimicrobial resistance. This study highlights the potential role of wild boars as carriers of Salmonella and could pose a risk to wild and domestic animals as well as humans.

Antimicrobial Resistance and PFGE Molecular Typing of Salmonella enterica serovar Gallinarum Isolates from Chickens in South Korea from 2013 to 2018.

Simple SummarySalmonella enterica serovar Gallinarum (S. enterica ser. Gallinarum) is a host-specific agent of fowl typhoid (FT). This is one of the most important bacterial infections in the poultry industry in both developing and developed countries, including South Korea. The use of antimicrobial drugs is the first choice for disease control. Antimicrobials, such as β-lactams, aminoglycosides, and fluoroquinolones, are frequently used to treat FT. However, the continuous use of antimicrobial drugs has led to the emergence and persistence of antimicrobial-resistant S. enterica ser. Gallinarum. In this study, we analyzed the antimicrobial susceptibility and epidemiological relationship of thirty isolates of S. enterica ser. Gallinarum isolated from poultry farms with an FT outbreak from 2013 to 2018 in South Korea. All the isolates showed a multi-drug resistant (MDR) phenotype. This study confirmed horizontal transmission and cross-contamination between farms within the same integrated poultry company or between farms belonging to different companies. The characterization of these isolates would be helpful to develop prevention and control strategies for the MDR S. enterica ser. Gallinarum infection in South Korea.Antimicrobial resistance and pulsed-field gel electrophoresis (PFGE) genotypes of collected S. enterica ser. Gallinarum isolates were investigated to examine the epidemiological relationship between field outbreak isolates of S. enterica ser. Gallinarum. Thirty S. enterica ser. Gallinarum isolates collected from poultry farms with FT outbreaks from 2013 to 2018 in South Korea were analyzed. All isolates were resistant to at least 3 of the 18 antimicrobials tested and exhibited an MDR phenotype. All isolates showed resistance to streptomycin, sulfisoxazole, and colistin. One isolate was resistant to 9 antimicrobials. The antimicrobial resistance profile, streptomycin-sulfisoxazole-colistin-nalidixic acid-ciprofloxacin-gentamicin (18/30, 60.0%), was the most prevalent. PFGE types were classified into 10 groups with a 100% correlation cutoff in dendrograms for 30 field isolates. The dominant PFGE types were 1 (8/30, 26.7%), 4 (7/30, 23.3%), and 9 (5/30, 16.7%). Interestingly some isolates collected from the same and different companies had the same PFGE type. We reported a high MDR rate in S. enterica ser. Gallinarum isolates. The present study highlights the occurrence of horizontal spread and cyclic contamination of MDR S. enterica ser. Gallinarum within the same company. Furthermore, we showed cross-contamination between different companies. The characterization of these isolates would be helpful in the development of prevention and control strategies for MDR S. enterica ser. Gallinarum infection in South Korea.

Sensory evaluation and antimicrobial activity of snack bar from black soybean and black rice containing anthocyanins

Snack bars made from black soybean and black rice could be used as a food product to complement the energy and nutrients needs. Both have anthocyanins content in black soybean and black rice as well as the potential as an antimicrobial agent. The purpose of this study was to obtain an optimal formula, evaluate the sensory acceptance, analyze the total monomeric anthocyanin content of the snack bars, and compare the growth of probiotic and pathogenic bacteria in anthocyanins crude extracts from the snack bars. The production of snack bars was done by using three variations of main ingredients, including 30% of black soybean + 70% of black rice (formula 1), 50% of black soybean + 50% of black rice (formula 2), and 70% of black soybean + 30% of black rice (formula 3). The results performed that consumers acceptance for formulas 2 and 3 was not significantly different (P &gt; 0.05), but significantly higher (P &lt; 0.05) than formula 1. Total monomeric anthocyanin content analyzed by the pH differential method in these three snack bars formulas had no significant difference (P &gt; 0.05). The growth analysis of probiotic and pathogenic bacteria showed that the percentage of growth inhibition of Escherichia coli and Salmonella enterica serovar Typhi bacteria was significantly higher (P = 0.00) compared to Lactobacillus acidophilus. Also, formulas 1 and 2 could significantly inhibit E. coli and S. enterica ser. Typhi bacteria (P = 0.00) compared to formula 3. It could be concluded that formula 2 showed the best snack bar based on sensory evaluation and pathogenic bacteria inhibition assay.

Effects of Salmonella enterica ser. Enteritidis and Heidelberg on host CD4+CD25+ regulatory T cell suppressive immune responses in chickens.

Poultry infected with Salmonella mount an immune response initially, however the immune responses eventually disappear leading the bird to be a carrier of Salmonella. The hypothesis of this study is that Salmonella infection induces T regulatory cell numbers and cytokine production and suppress host T cells locally in the gut to escape the host immune responses. An experiment was conducted to comparatively analyze the effect of S. enterica ser. Enteritidis (S. Enteritidis) and S. enterica ser. Heidelberg (S. Heidelberg) infection on CD4+CD25+ T regulatory cell properties in chickens. A total of 144 broiler chicks were randomly distributed into three experimental groups of non-infected control, S. Enteritidis infected and S. Heidelberg infected groups. Chickens were orally inoculated with PBS (control) or 5x106 CFU/mL of either S. Enteritidis or S. Heidelberg at 3 d of age. Each group was replicated in six pens with eight chickens per pen. Chickens infected with S. Enteritidis had 6.2, 5.4, and 3.8 log10 CFU/g, and chickens infected with S. Heidelberg had 7.1, 4.8, and 4.1 log10 CFU/g Salmonella in the cecal contents at 4, 11, and 32 dpi, respectively. Both S. Enteritidis and S. Heidelberg were recovered from the liver and spleen 4 dpi. At 4, 11, and 32 dpi, chickens infected with S. Enteritidis and S. Heidelberg had increased CD4+CD25+ cell numbers as well as IL-10 mRNA transcription of CD4+CD25+ cells compared to that in the control group. CD4+CD25+ cells from S. Enteritidis- and S. Heidelberg-infected chickens and restimulated with 1 μg antigen in vitro, had higher (P < 0.05) IL-10 mRNA transcription than the CD4+CD25+ cells from the non-infected controls Though at 4dpi, chickens infected with S. Enteritidis and S. Heidelberg had a significant (P < 0.05) increase in CD4+CD25- IL-2, IL-1β, and IFNγ mRNA transcription, the CD4+CD25- IL-2, IL-1β, and IFNγ mRNA transcription, were comparable to that in the control group at 11 and 32dpi identifying that the host inflammatory response against Salmonella disappears at 11 dpi. It can be concluded that S. Enteritidis and S. Heidelberg infection at 3 d of age induces a persistent infection through inducing CD4+CD25+ cells and altering the IL-10 mRNA transcription of CD4+CD25+ cell numbers and cytokine production in chickens between 3 to 32 dpi allowing chickens to become asymptomatic carriers of Salmonella after 18 dpi.

Evaluation of Safety and Protective Efficacy of a waaJ and spiC Double Deletion Korean Epidemic Strain of Salmonella enterica Serovar Gallinarum.

With an aim to develop a highly attenuated and strongly immunogenic distinguishable vaccine candidate, a waaJ (a gene involved in the synthesis of lipopolysaccharide) and spiC (a virulence gene) double deletion Korean epidemic strain of S. enterica ser. Gallinarum (SG005) was constructed. Our results showed that the growth and biochemical characteristics were not altered by this double deletion. The double deletion strain contained dual markers. One was a bacteriological marker (rough phenotype) and the other was a serological marker helping distinguish infected chickens from vaccinated chickens. The double deletion strain showed good genetic stability and reduced resistance to environmental stresses in vitro; furthermore, it was extremely safe and highly avirulent in broilers. Single intramuscular or oral immunization of 7-day-old broilers with the double deletion strain could stimulate the body to produce antibody levels similar to the conventional vaccine strain SG9R. In addition, against a lethal wild-type challenge, it conferred effective protection that was comparable to that seen in the group vaccinated with SG9R. In conclusion, this double deletion strain may be an effective vaccine candidate for controlling S. enterica ser. Gallinarum infection in broilers.