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This study aimed to determine the prevalence of Listeria spp. in fresh shrimp in Bogor, Indonesia, and to determine the antibiotic susceptibility patterns of isolated Listeria spp. A quantitative descriptive approach was employed. A total of 25 samples of fresh shrimp were obtained from randomly selected traditional markets (n = 18) and modern markets (n = 7). The results revealed that 14 samples (56.0%) were positive for Listeria spp. Among them, 11 (78.6%) and 3 (21.4%) were selected from traditional markets and modern markets, respectively. Thirty-six isolates, which upon biochemical characterization included 1 (2.8%) Listeria innocua, 26 (72.2%) Listeria grayi, 1 (2.8%) Listeria welshimeri, and 8 (22.2%) Listeria-like strains, were identified. The most common isolates were L. grayi, while the least common were L. innocua and L. welshimeri. The disk diffusion assay determined the susceptibility of the 36 strains to 10 commercial antibiotics. In general, 100% of the 36 isolated Listeria spp. were resistant to amoxicillin and nebacetin, and almost 100% were susceptible to chloramphenicol. However, antibiotic multiple resistance (AMR) was observed, with all Listeria strains resistant to more than two antibiotics. No isolate was resistant to only one antibiotic. The present study provides the first baseline data on the prevalence of Listeria spp. in fresh shrimp in Indonesia and the susceptibility of these isolates to antibiotics. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Food Safety & Quality is the property of Journal of Food Safety & Quality Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Fresh, ready-to-eat produce is frequently irrigated with untreated water, making it a leading cause of foodborne illness outbreaks worldwide. This study investigated the presence of Listeria monocytogenes in fresh produce that was grown using river water. Standard biochemical tests were used for the identification of L. monocytogenes isolated from river water used for irrigation, and from fresh produce including lettuce, spinach, and pumpkin. The inlA gene of L. monocytogenes was molecularly identified using PCR amplification. The susceptibility of L. monocytogenes isolates to antimicrobial agents was assessed using the Kirby-Bauer disc diffusion method. The presence of the amplified inlA gene (800 bp) indicated that all of the fresh produce and river water samples were contaminated with virulent L. monocytogenes. Lettuce and spinach exhibited higher quantities of L. monocytogenes, with lettuce recording 87 CFU/g and spinach recording 71 CFU/g. The L. monocytogenes isolates from spinach and lettuce sources showed significant resistance to colistin (56.2% and 53.3%, respectively) as well as ampicillin (68.8% and 53.3%, respectively). Moreover, lettuce (40%) and spinach (31%) exhibited a common resistance pattern of AMP-CHL-CT-KAN-PIP-ERY-TET, with a maximum MAR index value of 0.54. Our research demonstrates the transmission of multidrug-resistant L. monocytogenes from irrigation river water to fresh produce. Hence, the ingestion of ready-to-eat fresh produce carries the potential for human listeriosis, particularly among individuals with compromised immune systems. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles. [ABSTRACT FROM AUTHOR]

The study determined the antimicrobial resistance (AMR) profiles of Listeria spp. (L. monocytogenes, L. innocua, and L. welshimeri) recovered from beef and beef products sold at retail outlets in Gauteng Province, South Africa. A total of 112 isolates of Listeria spp., including L. monocytogenes (37), L. innocua (65), and L. welshimeri (10), were recovered from beef and beef products collected from 48 retail outlets. Listeria spp. was recovered by direct selective plating following selective enrichment, and PCR was used to confirm and characterize recovered isolates. The disc diffusion method determined the resistance to 16 antimicrobial agents. All 112 isolates of Listeria spp. exhibited resistance to one or more antibiotics (P

Copyright of Harran University Journal of the Faculty of Veterinary Medicine / Harran Üniversitesi Veteriner Fakültesi Dergisi is the property of Harran University, Faculty of Veterinary Medicine and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Although milk is a primary source of high-quality protein and accessible nutrients, it also represents the ideal habitat for the growth of a range of pathogenic microorganisms such as Listeria monocytogenes that cause listeriosis in human populations. Globally, the demand for dairy products has grown significantly in recent decades and Albania shares the same patterns in terms of consuming milk and dairy products. The increase in production in this sector goes hand in hand with the raising of awareness to ensure the quality and safety of milk to fulfill the demand of local and wider consumers. Based on the aforementioned, the main aim of this study is to evaluate the occurrence and persistence of Listeria spp. and Listeria monocytogenes in different processed milk samples marketed in small retailers in Tirana city. A total of 252 milk samples were collected from small retailers in six different areas in Tirana. All the samples are divided into three major categories based on their technological process: Pasteurized Milk (PM) samples (n = 90), Ultra High Temperature (UHT) milk samples (n = 126), and Sterilized Milk (SM) samples (n = 36). Furthermore, all the samples belonged to different dairy companies from Albania, dairy companies from the Western Balkans, and dairy companies from the European Union. Growth, isolation, and confirmation of Listeria spp. and Listeria monocytogenes were performed following ISO 11290-1:2017 protocol. All the data were analyzed with the statistical program SPSS 29.00. Our data show that the prevalence and persistence of L. monocytogenes and Listeria spp. depend on the technological process that the milk samples were subjected to. Listeria monocytogenes was detected in 12.2% (n = 11) of the total PM samples analyzed and in 0.79% (n = 1) of the total UHT milk samples analyzed. None of the SM samples resulted positive for the presence of Listeria monocytogenes. The paired t-test shows a statistically significant difference in means between the type of processed milk and milk samples that resulted positive for the presence of Listeria monocytogenes t (13) = 4.809, p <.001. The data presented in this research have underlined gaps that need to be filled regarding pathogen control throughout the whole chain of milk production, and marketing environments up to consumers. Future research should consider the examination of milk processing environments in Albania for better traceability of Listeria monocytogenes in milk. [ABSTRACT FROM AUTHOR]

Small- and medium-sized dairy processing facilities (SMDFs) may face unique challenges with respect to controlling Listeria in their processing environments, e.g., due to limited resources. The aim of this study was to implement and evaluate environmental monitoring programs (EMPs) for Listeria control in eight SMDFs in a ∼1-year longitudinal study; this included a comparison of pre-operation (i.e., after cleaning and sanitation and prior to production) and mid-operation (i.e., at least 4 h into production) sampling strategies. Among 2,072 environmental sponge samples collected across all facilities, 272 (13%) were positive for Listeria. Listeria prevalence among pre- and mid-operation samples (15% and 17%, respectively), was not significantly different. Whole genome sequencing (WGS) performed on select isolates to characterize Listeria persistence patterns revealed repeated isolation of closely related Listeria isolates (i.e., ≤20 high-quality single nucleotide polymorphism [hqSNP] differences) in 5/8 facilities over >6 months, suggesting Listeria persistence and/or reintroduction was relatively common among the SMDFs evaluated here. WGS furthermore showed that for 41 sites where samples collected pre- and mid-operation were positive for Listeria, Listeria isolates obtained were highly related (i.e., ≤10 hqSNP differences), suggesting that pre-operation sampling alone may be sufficient and more effective for detecting sites of Listeria persistence. Importantly, our data also showed that only 1/8 of facilities showed a significant decrease in Listeria prevalence over 1 year, indicating continued challenges with Listeria control in at least some SMDFs. We conclude that options for simplified Listeria EMPs (e.g., with a focus on pre-operation sampling, which allows for more rapid identification of likely persistence sites) may be valuable for improved Listeria control in SMDFs.

This study aimed to explore the probiogenomic characteristics of artisanal bacteriocin-producing Enterococcus faecium BGZLM1-5 and its potential application in reducing Listeria monocytogenes in a milk model. The BGZLM1-5 strain was isolated from raw cow's milk from households in the Zlatar Mountain region. The whole genome sequencing approach and bioinformatics analyses reveal that the strain BGZLM1-5 is non-pathogenic to humans. Bacteriocin-containing supernatant was thermally stable and antimicrobial activity retained 75% of the initial activity compared with that of the control after treatment at 90 °C for 30 min. Antimicrobial activity maintained relative stability at pH 3–11 and retained 62.5% of the initial activity compared with that of the control after treatment at pH 1, 2, and 12. The highest activity of the partially purified bacteriocin was obtained after precipitation at 40% saturation with ammonium sulfate and further purification by mixing with chloroform. Applying 3% and 5% (v/v) of the bacteriocin-containing supernatant and 0.5% (v/v) of the partially purified bacteriocin decreased the viable number of L. monocytogenes ATCC19111 after three days of milk storage by 23.5%, 63.5%, and 58.9%, respectively. [ABSTRACT FROM AUTHOR]

Lactic acid bacteria due to the safety reason is used in food industry in fermentation and in medicine as a bacteriocins. The aim of this study is to isolate Lactic Acid Bacteria from raw cow's milk and traditional Sharri cheese, and investigate their antimicrobial effects against Staphylococcus aureus, Listeria monocytogenes, Listeria ivanovii, and Listeria innocua. A total of 110 strains were isolated from milk samples of five farmers and samples of two traditional cheese producers. Among them, 47 strains exhibited inhibitory activity against at least one pathogenic indicator, with 20 isolates originating from milk samples and 27 from cheese samples. Eleven strains could inhibit the growth of all tested pathogenic indicators. Specifically, 68.08% of the isolates showed inhibitory activity against Staphylococcus aureus, 51.06% against Listeria monocytogenes, 48.94% against Listeria innocua, and 36.17% against Listeria ivanovii. These findings suggest that LAB cultures isolated from milk and artisanal cheese can serve as potential starter cultures in milk processing technology, which can help promote food security. [ABSTRACT FROM AUTHOR]

The chestnut industry generates large quantities of by-products, including the chestnut shell, which is a source of phenolic compounds. In this study, the MIC (minimum inhibitory concentration) of chestnut shell extract was determined using the disk diffusion method. The chestnut shell was freeze-dried and milled. The extract was obtained using an ultrasound-assisted technique using water 70%: ethanol 30% (v/v) and subsequently lyophilized. Muller–Hinton plates were inoculated with ~105 CFU/mL of microorganisms. Sterile paper discs (6 mm) were placed on the inoculated culture medium and impregnated with 10 µL of each extract. Seven concentrations of extract between 0.3% and 2.1% were tested. The plates were incubated for 24 h at 37 °C. The antibacterial efficacy of the extracts was indicated by a halo formed around the paper disk. This work was carried out in triplicate. Halos were found at 1.5%, 1.8%, and 2.1% on Listeria monocytogenes ATCC 7973 (8.32 ± 0.06 mm for 2.1%), Enterococcus faecalis 19433 (8.94 ± 0.41 mm for 2.1%), and Staphylococcus aureus ATCC (10.26 ± 0.19 mm at 2.1%). For the remaining microorganisms, no halos were observed. The tested extract showed antimicrobial activity, demonstrating its potential for the control of pathogens in the food industry. [ABSTRACT FROM AUTHOR]

Listeria monocytogenes is a ubiquitous pathogen found both in the environment and food. It can cause listeriosis in a wide range of animals as well as in humans. Investigations on presence, spread and virulence are still limited to terrestrial and human environments. Embracing the One Health Approach, investigating the presence and spread of L. monocytogenes in marine ecosystems and among wildlife, would provide us with useful information for human health. This study investigated the presence of L. monocytogenes and Listeria spp. in two species of sea turtles common in the Mediterranean Sea (Caretta caretta and Chelonia mydas). A total of one hundred and sixty-four carcasses of sea turtles (C. caretta n = 161 and C. mydas n = 3) stranded along the Abruzzo, Molise, Campania, and Calabria coasts, were collected. Brain and fecal samples were taken, enriched, and cultured for the detection of Listeria spp. From the specimens collected, strains of L. monocytogenes (brain n = 1, brain and feces n = 1, multiorgan n = 1 and feces n = 1), L. innocua (feces n = 1 and brain n = 1), and L. ivanovii (brain n = 1) were isolated. Typical colonies were isolated for Whole Genome Sequencing (WGS). Virulence genes, disinfectants/metal resistance, and antimicrobial resistance were also investigated. L. monocytogenes, L. innocua, and L. ivanovii were detected in C. caretta, whilst only L. monocytogenes and L. innocua in C. mydas. Notable among the results is the lack of significant differences in gene distribution between human and sea turtle strains. Furthermore, potentially pathogenic strains of L. monocytogenes were found in sea turtles.

The safety of food production as concerns Listeria is the key to the sanitary wellbeing of manufactured products. Molecular-genetic methods for the analysis of Listeria, including whole-genome sequencing, are effective in monitoring persistent contaminants and in the epidemic investigation of cases of foodborne infections. They have been adopted in the European Union, United States, and Canada. In Russia, multilocus and whole-genome sequencing has proven itself in the analysis of clinical food isolates and Listeria from the environment. The objective of the study was molecular-genetic characterization of Listeria detected in the industrial environment of meat processing. To characterize the Listeria isolates, microbiological methods were used according to GOST (State Standard) 32031–2012, as well as multilocus sequencing, including the analysis of seven housekeeping genes and four virulence genes, as well as whole-genome sequencing. In swabs that were positive for the presence of Listeria spp. taken at two meat-processing plants in Moscow, Listeria monocytogenes constituted 81% and L. welshimeri 19%. The predominant genotype (Sequence Type, ST) of L. monocytogenes was ST8. The variety was supplemented with ST321, ST121, and ST2330 (CC9 (Clonal Complex 9)). L. welshimeri, which prevailed in the second production, was represented by ST1050 and ST2331. The genomic characteristics of L. welshimeri isolates confirmed that they have high adaptive capabilities both as concerns production conditions (including resistance to disinfectants) and the metabolic peculiarities of the gastrointestinal tract of animals. L. monocytogenes CC9 and CC121 are also correlated with food production in other countries. However, L. monocytogenes CC8 and CC321 can cause invasive listeriosis. The concordance in the internalin profile of the ST8 isolates from the industrial environment with the clinical isolates ST8 and ST2096 (CC8) is a cause for concern. The study showed the effectiveness of molecular-genetic methods in determining the diversity of Listeria detected in the production environment of meat processing, and laid the foundation for monitoring of persistent contaminants. [ABSTRACT FROM AUTHOR]

Strain ST182Gu, isolated from fresh guava fruit, was identified as Enterococcus casseliflavus on the basis of biochemical tests, sugar fermentation reactions (API20Strip), PCR with genus-specific primers, and 16S rRNA sequencing. This appears to be the first documentation of the presence of this species in guava. E. casseliflavus ST182Gu was shown to produce a 4.8 kDa class IIa bacteriocin, active against various lactic acid bacteria including Enterococcus spp. and Streptococcus spp., and Staphylococcus aureus, and different serotypes of Listeria spp. The activity of the peptide was reduced by treatment with 0.1 mg/mL proteolytic enzymes, but not by α-amylase, catalase, lipase, and 1% (w/v) sodium dodecyl sulphate (SDS), Tween-20, Tween-80, urea, NaCl, and EDTA. No change in activity was recorded after adjustment to pH values of between 2.0 and 12.0 for 2 h, and after treatment at 100 °C for 120 min or 121°C for 20 min, compared with non-treated antimicrobial peptide. The mode of action against representative susceptible bacteria was shown to be bactericidal and associated with cell lysis and enzyme- and DNA-leakage. These susceptible bacteria, Listeria ivanovii subsp. ivanovii ATCC 19119, Listeria monocytogenes ATCC 15313, and Enterococcus faecalis ATCC 19443 differed however in their sensitivity to bacteriocin ST182Gu (6,553,600 AU/mL, 102,400 AU/mL, and 51,200 AU/mL, respectively). No significant differences were detected in cell growth and bacteriocin production when strain ST182Gu was grown in MRS broth at 26 °C, 30 °C, and 37 °C for 24 h. Bacteriocin ST182Gu recovery from the surface of the producer cells showed different activity, dependent of the applied test organisms (3200, 800 and 400 AU/mL, evaluated versus L. ivanovii subsp. ivanovii ATCC 19119, L. monocytogenes ATCC 15313 and E. faecalis ATCC 19443, respectively), however, with proportional values with the activity recorded in cell free supernatant versus same test microorganisms. When bacteriocin ST182Gu was combined with sublethal doses of ciprofloxacin, synergistic inhibition of L. ivanovii subsp. ivanovii ATCC 19119 was demonstrated. This increase in ciprofloxacin sensitivity may be due to the dissipation of the proton gradient in the cell membrane of the target organism associated with exposure to bacteriocin ST182Gu. Apart from reducing the MIC of classical therapeutic antibiotics, bacteriocins such as ST182Gu may also play an important role in the treatment of multidrug resistant strains. [ABSTRACT FROM AUTHOR]

Beneficial bacteria with antibacterial properties are attractive alternatives to chemical-based antibacterial or bactericidal agents. Our study sourced such bacteria from horticultural produce and environments to explore the mechanisms of their antimicrobial properties. Five strains of Pseudomonas fluorescens were studied that possessed antibacterial activity against the pathogen Listeria monocytogenes. The vegetative culture of these strains (Pseudomonas fluorescens-PFR46I06, Pseudomonas fluorescens-PFR46H06, Pseudomonas fluorescens-PFR46H07, Pseudomonas fluorescens-PFR46H08 and Pseudomonas fluorescens-PFR46H09) were tested against Listeria monocytogenes (n = 31), Listeria seeligeri (n = 1) and Listeria innocua (n = 1) isolated from seafood and horticultural sources and from clinical cases (n = 2) using solid media coculture and liquid media coculture. All Listeria strains were inhibited by all strains of P. fluorescens; however, P. fluorescens-PFR46H07, P. fluorescens-PFR46H08 and P. fluorescens-PFR46H09 on solid media showed good inhibition, with average zones of inhibition of 14.8 mm, 15.1 mm and 18.2 mm, respectively, and the other two strains and P. fluorescens-PFR46H09 had a significantly greater zone of inhibition than the others (p < 0.05). There was no inhibition observed in liquid media coculture or in P. fluorescens culture supernatants against Listeria spp. by any of the P. fluorescens strains. Therefore, we hypothesized that the structural apparatus that causes cell-to-cell contact may play a role in the ejection of ant-listeria molecules on solid media to inhibit Listeria isolates, and we investigated the structural protein differences using whole-cell lysate proteomics. We paid special attention to the type VI secretion system (TSS-T6SS) for the transfer of effector proteins or bacteriocins. We found significant differences in the peptide profiles and protein summaries between these isolates' lysates, and PFR46H06 and PFR46H07 possessed the fewest secretion system structural proteins (12 and 11, respectively), while PFR46H08 and PFR46H09 had 18 each. P. fluorescens-PFR46H09, which showed the highest antimicrobial effect, had nine tss-T6SS structural proteins compared to only four in the other three strains. [ABSTRACT FROM AUTHOR]

This study aimed to explore the probiogenomic characteristics of artisanal bacteriocin-producing Enterococcus faecium BGZLM1-5 and its potential application in reducing Listeria monocytogenes in a milk model. The BGZLM1-5 strain was isolated from raw cow’s milk from households in the Zlatar Mountain region. The whole genome sequencing approach and bioinformatics analyses reveal that the strain BGZLM1-5 is non-pathogenic to humans. Bacteriocin-containing supernatant was thermally stable and antimicrobial activity retained 75% of the initial activity compared with that of the control after treatment at 90 °C for 30 min. Antimicrobial activity maintained relative stability at pH 3–11 and retained 62.5% of the initial activity compared with that of the control after treatment at pH 1, 2, and 12. The highest activity of the partially purified bacteriocin was obtained after precipitation at 40% saturation with ammonium sulfate and further purification by mixing with chloroform. Applying 3% and 5% (v/v) of the bacteriocin-containing supernatant and 0.5% (v/v) of the partially purified bacteriocin decreased the viable number of L. monocytogenes ATCC19111 after three days of milk storage by 23.5%, 63.5%, and 58.9%, respectively.

Aim: In this study, it was aimed to determine the presence of Vibrio spp., Aeromonas spp., and Listeria spp. in finned fish and shrimps consumed in Turkey and the antibiotic resistance profile of the isolates using disc diffusion method. Materials and Methods: In the research, 300 seafoods obtained at different times were used as material. Following isolation by classical cultural method, classical PCR was performed to confirm the isolates at genus level and to identify at species level for pathogenic species. Results: Finfish and shrimp samples were contaminated with Vibrio spp., Aeromonas spp. and Listeria spp. with the rate of 19.4% (33/170), 14.7% (25/170), 4.1% (7/170) and 13.8% (18/130), 13.1% (17/130), 6.2% (8/130), respectively. Twenty-nine (9.7%) and 9 (3.0%) of the Vibrio spp. isolates were identified as V. parahaemolyticus and V. cholerae, respectively. Thirty (10%) of the Aeromonas spp. isolates were detected as A. hydrophila. L. monocytogenes and V. vulnificus was not detected in any of samples. Antibiotic resistance profile of the V. parahaemolyticus, V. cholerae, A. hydrophila and Listeria spp. isolates was streptomycin (71.4%), teicoplanin (71.4%), ampicillin (87.5%), teicoplanin (75%); streptomycin (80%), ampicillin (75%), cefixime (75%), penicillin (75%), sulfamethoxazole/trimethoprim (100%), tetracycline (75%); erythromycin (93.8%), vancomycin (81.2%), amoxacillin/clavulanic acid (78.6%), ampicillin (85.7%), cephalothin (92.9%), penicillin G (92.9%); and cephalothin (37.5%-42.9%), erythromycin (37.5%-42.9%), penicillin G (37.5%-42.9%), tetracycline (37.5%-42.9%), respectively. Conclusion: As a result, it is thought that fish and shrimp consumed in Turkey may be contaminated with pathogenic Vibrio and Aeromonas species, and antibiotic-resistant isolates may pose a risk to public health.

Objective: The work aimed to assess the safety and quality of broiler meat in experimental liste¬riosis changes in storage. Materials and Methods: Ross Cobb 500 chickens (40) were divided into 4 groups of 10 animals each. Chickens from three experimental groups were infected by Listeria innocua, Listeria ivanovii, and Listeria monocytogenes. Meat samples were stored for 5 days at 0°C–4°C. Meat samples were kept in the refrigerator for 3, 4, and 5 days. Microbiological and laboratory indicators of meat freshness were found on these days as well. Results: After the slaughter of chickens with experimental listeriosis, pathological changes in mus¬cles and organs were noted against the background of fattening carcasses with a high slaughter yield. By bacterial contamination, 1 day after slaughter, the meat of chickens of the experimental groups (L. innocua, L. ivanovii, and L. monocytogenes) outperformed the control group by almost 1.9, 13.9, and 24.7 times, respectively (p < 0.05). The same trend is observed for the third, fourth, and fifth days of meat storage. To keep chicken meat fresh for 5 days, only samples from the con¬trol group stayed fresh. Conclusion: According to the total bacterial contamination, the meat of chickens of the groups L. innocua and L. ivanovii was dangerous to human health after 5 and 4 days of storage, respec¬tively. From the first day after the chickens were killed, the meat of chickens that had been infected with L. monocytogenes did not meet the requirements (up to 100 CFU/gm) and was not safe to store or eat. [J Adv Vet Anim Res 2022; 9(1.000): 155-165]

ABSTRACT Listeria monocytogenes, a foodborne pathogen, and other Listeria spp. are present in natural environments. Isolating and characterizing strains from natural reservoirs can provide insight into the prevalence and diversity of Listeria spp. in these environments, elucidate their contribution to contamination of agricultural and food processing environments and food products, and lead to the discovery of novel species. In this study, we evaluated the diversity of Listeria spp. isolated from soil in a small region of the Great Smoky Mountains National Park, the most biodiverse national park in the U.S. National Park system. Of the 17 Listeria isolates recovered, whole-genome sequencing revealed that 14 were distinct strains. The strains represented a diversity of Listeria species (L. monocytogenes [n = 9], L. cossartiae subsp. cossartiae [n = 1], L. marthii [n = 1], L. booriae [n = 1], and a potentially novel Listeria sp. [n = 2]), as well as a diversity of sequence types based on multilocus sequence typing (MLST) and core genome MLST, including many novel designations. The isolates were not closely related (≥99.99% average nucleotide identity) to any isolates in public databases (NCBI, PATRIC), which also indicated novelty. The Listeria samples isolated in this study were collected from high-elevation sites near a creek that ultimately leads to the Mississippi River; thus, Listeria present in this natural environment could potentially travel downstream to a large region that includes portions of nine southeastern and midwestern U.S. states. This study provides insight into the diversity of Listeria spp. in the Great Smoky Mountains and indicates that this environment is a reservoir of novel Listeria spp. IMPORTANCE Listeria monocytogenes is a foodborne pathogen that can cause serious systemic illness that, although rare, usually results in hospitalization and has a relatively high mortality rate compared to other foodborne pathogens. Identification of novel and diverse Listeria spp. can provide insights into the genomic evolution, ecology, and evolution and variance of pathogenicity of this genus, especially in natural environments. Comparing L. monocytogenes and Listeria spp. isolates from natural environments, such as those recovered in this study, to contamination and/or outbreak strains may provide more information about the original natural sources of these strains and the pathways and mechanisms that lead to contamination of food products and agricultural or food processing environments.

This study investigated the eggs of Polish-bred edible snails of the Cornu genus as a food and aimed to determine the presence of microorganisms in them of the Salmonella and Listeria genera and ascertain the number of coagulase-positive staphylococci.

The catfish industry is important to the United States economy. The present study determined the levels of microbial indicators and the prevalence of Listeria spp. and Listeria monocytogenes at catfish farms and catfish processing plants. Live fish, water, and sediment samples were analyzed in farms. Fish skin, fillets, chiller water, and environmental surfaces were assessed at the processing plants both during operation and after sanitation. Live fish had 2% prevalence of Listeria monocytogenes, while sediment and water were negative for Listeria. Live fish skin counts averaged 4.2, 1.9, and 1.3 log CFU/cm2 aerobic (APC), total coliform (TCC) and generic Escherichia coli counts, respectively. Water and sediment samples averaged 4.8 and 5.8 log CFU/g APC, 1.9 and 2.3 log CFU/g TCC, and 1.0 and 1.6 log CFU/g generic E. coli counts, respectively. During operation, Listeria prevalence was higher in fillets before (57%) and after (97%) chilling than on fish skin (10%). Process chiller water had higher (p ≤ 0.05) APC, TCC, and Listeria prevalence than clean chiller water. After sanitation, most sampling points in which Listeria spp. were present had high levels of APC (>2.4 log CFU/100 cm2). APC combined with Listeria spp. could be a good approach to understand microbial contamination in catfish plants. [ABSTRACT FROM AUTHOR]

Abstract Listeriosis, caused by Listeria spp., presents varying clinical manifestations among individuals, from moderate fecal infections such as diarrhea to severe infections such as septicemia, meningitis and abortion or newborn listeriosis in perinatal patients. In Africa, listeriosis is attributed to poor sanitation and cross-contamination in food processing environments, particularly ready to eat (RTE) foods including dairy products, leafy vegetables, fish and meat. Despite the global increase in reported cases and research on listeriosis, data from Africa remains scarce and this could lead to possible underestimation of the importance of listeriosis on the continent. This paper therefore presents a comprehensive overview of currently available reports on Listeria spp. in Africa with emphasis on molecular characteristics, antimicrobial susceptibility, and prevalence in food, animal and environmental samples. The majority of studies on Listeria spp. in Africa have so far focused on the prevalence and antibiotic susceptibility of L. monocytogenes isolated from RTE foods and raw meat but rarely from humans, animals, and the environment. The overall calculated average prevalence values from the available reports are 23.7 and 22.2% for Listeria spp. and L. monocytogenes, respectively. Listeria spp. isolated from different parts of Africa are generally sensitive to ciprofloxacin, but resistant to penicillin. The majority of these studies employed conventional culture and biochemical tests to characterize Listeria spp. However, the use of modern molecular techniques such as PCR and whole-genome sequencing is on the rise. Most of the studies employing molecular tools were carried out in South Africa and Nigeria, with the predominant strain reported in South Africa being ST6. In order to provide a better understanding of the importance of listeria in Africa, there is the need for extensive and coordinated studies using modern molecular-based techniques to characterize the various Listeria species, and to assess the disease epidemiology using the one health concept.

In Ukraine zoonoses are a permanent threat to human health, some of them are bacterial diseases associated with farm animals. Complete avoidance of outbreaks of bacterial zoonoses is not possible but it is appropriate to study them to reduce the risks of transmission of zoonosis pathogens from industrial farms to the human population and the environment. The article highlights the results of a literature review on the potential role of industrial livestock farms in the spread of major bacterial zoonoses in Ukraine. About half of all of the country’s farmed animals are kept on farms using industrial technology; more than half of the establishments are classified as medium and large. The technology of keeping animals on such farms contributes to the development of diseases of obligate hosts caused by fecal bacteria. The systematic search and selection of literary sources, which are relevant to the topic of the study were carried out. The vast majority of analyzed publications are published in Ukrainian in local peer-reviewed scientific journals. An analysis of open-access official statistics from the state authorities of Ukraine was also conducted. The authors analyzed statistics and scientific papers published over the last 10–15 years discussing the outbreaks of food-borne zoonoses among humans and the studying their pathogens (Campylobacter spp., Salmonella spp., Escherichia coli (STEC strains), Listeria spp.) on industrial livestock farms. The main source of Campylobacter spp. and Salmonella spp. distribution are industrial poultry, including broilers and chickens, respectively. The STEC strains E. coli carriers are various types of farm animals, including cattle and pigs. The majority of infections documented in Ukraine are cases of salmonellosis in humans and animals. Despite reports of a significant prevalence of campylobacteriosis, colibacillosis and listeriosis in livestock farms, their association with outbreaks of food-borne zoonoses in humans remains poorly understood. The concept of an industrial livestock farm involves a permanent presence of a risk of outbreaks of bacterial zoonoses and their rapid spreading to the human population. This is due to concentrated maintenance of animals, standardized feeding, the priority of achieving the highest productivity of animals and economic indicators. Under such conditions, disturbance of hygienic norms and technologies significantly increases the risk of bacterial zoonoses on industrial farms. It is important to enforce the continuous control of the level of microbial pollution of farms, animal health, hygiene of milk production and processing, meat, eggs, etc. Farms have a negative impact on the ecological welfare of the surrounding territories. The problem of spread of antibiotic-resistant strains of bacterial zoonoses is a very serious one. Efforts for the formation of a national system of epidemiological supervision over bacterial zoonoses, comprising epidemiological, epizootological, ecological, microbiological, serological and molecular genetic monitoring, as well as the development on this basis of effective prophylactic and anti-epidemic measures are relevant and necessary.

Selection for Listeria monocytogenes strains that are tolerant to quaternary ammonium compounds (such as benzalkonium chloride [BC]) is a concern across the food industry, including in fresh produce processing environments. This study evaluated the ability of 67 strains of produce-associated L. monocytogenes and other Listeria spp. ("parent strains") to show enhanced BC tolerance after serial passaging in increasing BC concentrations and to maintain this tolerance after substreaking in the absence of BC. After serial passaging in BC, 62/67 "BC passaged cultures" showed higher MICs (4 to 20 mg/L) than parent strains (2 to 6 mg/L). After the substreaking of two isolates from BC passaged cultures for each parent strain, 105/134 "adapted isolates" maintained MICs (4 to 6 mg/L) higher than parent strain MICs. These results suggested that adapted isolates acquired heritable adaptations that confer BC tolerance. Whole-genome sequencing and Sanger sequencing of fepR, a local repressor of the MATE family efflux pump FepA, identified nonsynonymous fepR mutations in 48/67 adapted isolates. The mean inactivation of adapted isolates after exposure to use-level concentrations of BC (300 mg/L) was 4.48 log, which was not significantly different from inactivation observed in parent strains. Serial passaging of cocultures of L. monocytogenes strains containing bcrABC or qacH did not yield adapted isolates that showed enhanced BC tolerance in comparison to that of monocultures. These results suggest that horizontal gene transfer either did not occur or did not yield isolates with enhanced BC tolerance. Overall, this study provides new insights into selection of BC tolerance among L. monocytogenes and other Listeria spp. [ABSTRACT FROM AUTHOR]

L. monocytogenes is a public health threat linked to fast foods such as broiler chickens. This study aimed to verify the occurrence of Listeria species in chickens from abattoirs and evaluate their antimicrobial resistance. In total, 150 broiler carcass swabs distributed as cloacal (n = 60), exterior surface (n = 60), and environmental (n = 30) were collected. Listeria species were characterized using biochemical tests and PCR. We conducted antibiotic resistance tests using the disc diffusion and Etest (Biomerieux, Durham, NC, USA) methods. Overall isolation of Listeria species was 15% (23/150) 95% CI (10.16–22.33), 2% (3/150) 95% CI (0.52–6.19) and 13% (20/150) 95% CI (8.53–20.08) came from environmental swabs and carcass swabs, respectively. Proportions of positive Listeria isolates were L. monocytogenes 74% (17/23), L. welshimeri 22% (5/23), and L. innocua 4% (1/23). Listeria species from the exterior carcass swabs was 61% (14/23), cloacal swabs 26% (6/23), and environmental swabs 3% (3/23). L. monocytogenes had the greatest resistance percentage to the following antibiotics: clindamycin (61%, 10/23), tetracycline 30% (7/23), and erythromycin 13%, (3/23). Isolation of L. monocytogenes in relatively high numbers, including the antimicrobial profiles, suggests a potential risk of the pathogen remaining viable in the food continuum and a public health risk to would-be consumers. [ABSTRACT FROM AUTHOR]

Camel milk is a valuable food choice, representing a primary need in the diet of people in dry zones. Camel milk is rich in nutrients, which makes it a favorable environment for the development of microorganisms. Staphylococcus and Listeria are significant opportunistic pathogens in humans, dairy cattle, and camels. The presence of these bacteria could present a potential public health issue. In the present study, 20 milk samples collected from camel farms in M'sila were investigated for the presence of Staphylococcus spp. and Listeria spp. Staphylococcus enumeration, and a search for Listeria spp. was performed according to the recommendations of ISO 6888-1(2004) and ISO 11290-1(2017) methods, respectively. The results show a contamination prevalence of 62% of staphylococcus spp. with an estimated average bacterial load of 2.7.102 cfu/mL, while for Listeria spp., only three samples were positive, with a prevalence of 14.28%. For each species, identification using API Listeria strips confirmed the presence of Listeria grayi, Listeria innocua, and Listeria seeligeri species, but no Listeria monocytogenes were recovered in these samples. According to the current results, we could conclude that the percentage of contamination with Staphylococcus in the tested camel milk samples was relatively high compared to the level of contamination with Listeria. There is no Algerian regulation setting microbiological criteria for raw camel milk; however, these results suggest that the hazard to the consumer cannot be excluded. [ABSTRACT FROM AUTHOR]

Objective: The work aimed to assess the safety and quality of broiler meat in experimental listeriosis changes in storage. Materials and Methods: Ross Cobb 500 chickens (40) were divided into 4 groups of 10 animals each. Chickens from three experimental groups were infected by Listeria innocua, Listeria ivanovii, and Listeria monocytogenes. Meat samples were stored for 5 days at 0°C-4°C. Meat samples were kept in the refrigerator for 3, 4, and 5 days. Microbiological and laboratory indicators of meat freshness were found on these days as well. Results: After the slaughter of chickens with experimental listeriosis, pathological changes in muscles and organs were noted against the background of fattening carcasses with a high slaughter yield. By bacterial contamination, 1 day after slaughter, the meat of chickens of the experimental groups (L. innocua, L. ivanovii, and L. monocytogenes) outperformed the control group by almost 1.9, 13.9, and 24.7 times, respectively (p < 0.05). The same trend is observed for the third, fourth, and fifth days of meat storage. To keep chicken meat fresh for 5 days, only samples from the control group stayed fresh. Conclusion: According to the total bacterial contamination, the meat of chickens of the groups L. innocua and L. ivanovii was dangerous to human health after 5 and 4 days of storage, respec- tively. From the first day after the chickens were killed, the meat of chickens that had been infected with L. monocytogenes did not meet the requirements (up to 100 CFU/gm) and was not safe to store or eat. [ABSTRACT FROM AUTHOR]

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The main microbiological hazards of raw milk cheese are associated with Listeria monocytogenes, Escherichia coli and Staphylococcus aureus. Due to its high nutritional value, cheese is an excellent medium for the growth of these pathogens. This study was aimed to observe microbial dynamics of Bulgarian white brined cheese during cheese production and ripening. Microbiological analysis in-cluded determination of Staphylococcus aureus, Listeria spp. and Escherichia coli counts. Some physicochemical parameters, such as total titratable acidity, sodium chloride content, water activity and pH were also examined. Results revealed statistically significant increase in bacterial counts after cheesemaking steps and decrease at the end of the ripening period. Listeria monocytogenes was not detected in any of the cheese samples. Raw milk cheese was of unsatisfactory quality that emphasises the need for applying and maintaining good hygiene practices along the food chain to prevent microbial contamination and growth.

This survey aimed to study the occurrence of Listeria species in fish and meat samples and characterization of their virulence genes. Over all, Listeria spp. was found in 25.22% samples out of which 9.0% and 16.21% were L. monocytogenes and L. innocua,respectively. L. monocytogenes (n=10) belonged to 4b, 4d and 4e serovars. All the isolates revealed presence of virulence genes- plcA and iap, while plcB gene was also present in 90% of the isolates. The occurrence of L. monocytogenes in samples shows cogent evidence for their zoonotic potential and has public health significance.

Camel milk is a valuable food choice, representing a primary need in the diet of people in dry zones. Camel milk is rich in nutrients, which makes it a favorable environment for the development of microorganisms. Staphylococcus and Listeria are significant opportunistic pathogens in humans, dairy cattle, and camels. The presence of these bacteria could present a potential public health issue. In the present study, 20 milk samples collected from camel farms in M’sila were investigated for the presence of Staphylococcus spp. and Listeria spp. Staphylococcus enumeration, and a search for Listeria spp. was performed according to the recommendations of ISO 6888-1(2004) and ISO 11290-1(2017) methods, respectively. The results show a contamination prevalence of 62% of staphylococcus spp. with an estimated average bacterial load of 2.7.102 cfu/mL, while for Listeria spp., only three samples were positive, with a prevalence of 14.28%. For each species, identification using API Listeria strips confirmed the presence of Listeria grayi, Listeria innocua, and Listeria seeligeri species, but no Listeria monocytogenes were recovered in these samples. According to the current results, we could conclude that the percentage of contamination with Staphylococcus in the tested camel milk samples was relatively high compared to the level of contamination with Listeria. There is no Algerian regulation setting microbiological criteria for raw camel milk; however, these results suggest that the hazard to the consumer cannot be excluded.

Strain ST182Gu, isolated from fresh guava fruit, was identified as Enterococcus casseliflavus on the basis of biochemical tests, sugar fermentation reactions (API20Strip), PCR with genus-specific primers, and 16S rRNA sequencing. This appears to be the first documentation of the presence of this species in guava. E. casseliflavus ST182Gu was shown to produce a 4.8 kDa class IIa bacteriocin, active against various lactic acid bacteria including Enterococcus spp. and Streptococcus spp., and Staphylococcus aureus, and different serotypes of Listeria spp. The activity of the peptide was reduced by treatment with 0.1 mg/mL proteolytic enzymes, but not by α-amylase, catalase, lipase, and 1% (w/v) sodium dodecyl sulphate (SDS), Tween-20, Tween-80, urea, NaCl, and EDTA. No change in activity was recorded after adjustment to pH values of between 2.0 and 12.0 for 2 h, and after treatment at 100 °C for 120 min or 121°C for 20 min, compared with non-treated antimicrobial peptide. The mode of action against representative susceptible bacteria was shown to be bactericidal and associated with cell lysis and enzyme- and DNA-leakage. These susceptible bacteria, Listeria ivanovii subsp. ivanovii ATCC 19119, Listeria monocytogenes ATCC 15313, and Enterococcus faecalis ATCC 19443 differed however in their sensitivity to bacteriocin ST182Gu (6,553,600 AU/mL, 102,400 AU/mL, and 51,200 AU/mL, respectively). No significant differences were detected in cell growth and bacteriocin production when strain ST182Gu was grown in MRS broth at 26 °C, 30 °C, and 37 °C for 24 h. Bacteriocin ST182Gu recovery from the surface of the producer cells showed different activity, dependent of the applied test organisms (3200, 800 and 400 AU/mL, evaluated versus L. ivanovii subsp. ivanovii ATCC 19119, L. monocytogenes ATCC 15313 and E. faecalis ATCC 19443, respectively), however, with proportional values with the activity recorded in cell free supernatant versus same test microorganisms. When bacteriocin ST182Gu was combined with sublethal doses of ciprofloxacin, synergistic inhibition of L. ivanovii subsp. ivanovii ATCC 19119 was demonstrated. This increase in ciprofloxacin sensitivity may be due to the dissipation of the proton gradient in the cell membrane of the target organism associated with exposure to bacteriocin ST182Gu. Apart from reducing the MIC of classical therapeutic antibiotics, bacteriocins such as ST182Gu may also play an important role in the treatment of multidrug resistant strains.

Beneficial bacteria with antibacterial properties are attractive alternatives to chemical-based antibacterial or bactericidal agents. Our study sourced such bacteria from horticultural produce and environments to explore the mechanisms of their antimicrobial properties. Five strains of Pseudomonas fluorescens were studied that possessed antibacterial activity against the pathogen Listeria monocytogenes. The vegetative culture of these strains (Pseudomonas fluorescens-PFR46I06, Pseudomonas fluorescens-PFR46H06, Pseudomonas fluorescens-PFR46H07, Pseudomonas fluorescens-PFR46H08 and Pseudomonas fluorescens-PFR46H09) were tested against Listeria monocytogenes (n = 31), Listeria seeligeri (n = 1) and Listeria innocua (n = 1) isolated from seafood and horticultural sources and from clinical cases (n = 2) using solid media coculture and liquid media coculture. All Listeria strains were inhibited by all strains of P. fluorescens; however, P. fluorescens-PFR46H07, P. fluorescens-PFR46H08 and P. fluorescens-PFR46H09 on solid media showed good inhibition, with average zones of inhibition of 14.8 mm, 15.1 mm and 18.2 mm, respectively, and the other two strains and P. fluorescens-PFR46H09 had a significantly greater zone of inhibition than the others (p < 0.05). There was no inhibition observed in liquid media coculture or in P. fluorescens culture supernatants against Listeria spp. by any of the P. fluorescens strains. Therefore, we hypothesized that the structural apparatus that causes cell-to-cell contact may play a role in the ejection of ant-listeria molecules on solid media to inhibit Listeria isolates, and we investigated the structural protein differences using whole-cell lysate proteomics. We paid special attention to the type VI secretion system (TSS-T6SS) for the transfer of effector proteins or bacteriocins. We found significant differences in the peptide profiles and protein summaries between these isolates’ lysates, and PFR46H06 and PFR46H07 possessed the fewest secretion system structural proteins (12 and 11, respectively), while PFR46H08 and PFR46H09 had 18 each. P. fluorescens-PFR46H09, which showed the highest antimicrobial effect, had nine tss-T6SS structural proteins compared to only four in the other three strains.

The study determined the antimicrobial resistance (AMR) profiles of Listeria spp. (L. monocytogenes, L. innocua, and L. welshimeri) recovered from beef and beef products sold at retail outlets in Gauteng Province, South Africa. A total of 112 isolates of Listeria spp., including L. monocytogenes (37), L. innocua (65), and L. welshimeri (10), were recovered from beef and beef products collected from 48 retail outlets. Listeria spp. was recovered by direct selective plating following selective enrichment, and PCR was used to confirm and characterize recovered isolates. The disc diffusion method determined the resistance to 16 antimicrobial agents. All 112 isolates of Listeria spp. exhibited resistance to one or more antibiotics (P < 0.05). The prevalence of AMR in Listeria isolates was high for nalidixic acid (99.1%) and cefotaxime (80.4%) but low for gentamycin (2.7%), sulfamethoxazole-trimethoprim (3.6%), azithromycin (5.4%), and doxycycline (6.3%). Overall, for the three species of Listeria, the prevalence of resistance varied significantly only for streptomycin (P = 0.016) and tetracycline (P = 0.034). Multidrug-resistant isolates were detected in 75.7% (28/37), 61.5% (40/65), and 80% (8/10) isolates of L. monocytogenes, L. innocua, and L. welshimeri, respectively. The prevalence of AMR was significantly affected by the location and size of retail outlets, type of beef and beef products, and serogroups of L. monocytogenes. The high prevalence of AMR, particularly among the L. monocytogenes isolates, poses potential therapeutic implications for human consumers of contaminated beef products. There is, therefore, a need to regulate and enforce the use of antimicrobial agents in humans and animals in South Africa., (Copyright © 2024. Published by Elsevier Inc.)

Listeriosis, caused by Listeria spp., presents varying clinical manifestations among individuals, from moderate fecal infections such as diarrhea to severe infections such as septicemia, meningitis and abortion or newborn listeriosis in perinatal patients. In Africa, listeriosis is attributed to poor sanitation and cross-contamination in food processing environments, particularly ready to eat (RTE) foods including dairy products, leafy vegetables, fish and meat. Despite the global increase in reported cases and research on listeriosis, data from Africa remains scarce and this could lead to possible underestimation of the importance of listeriosis on the continent. This paper therefore presents a comprehensive overview of currently available reports on Listeria spp. in Africa with emphasis on molecular characteristics, antimicrobial susceptibility, and prevalence in food, animal and environmental samples. The majority of studies on Listeria spp. in Africa have so far focused on the prevalence and antibiotic susceptibility of L. monocytogenes isolated from RTE foods and raw meat but rarely from humans, animals, and the environment. The overall calculated average prevalence values from the available reports are 23.7 and 22.2% for Listeria spp. and L. monocytogenes, respectively. Listeria spp. isolated from different parts of Africa are generally sensitive to ciprofloxacin, but resistant to penicillin. The majority of these studies employed conventional culture and biochemical tests to characterize Listeria spp. However, the use of modern molecular techniques such as PCR and whole-genome sequencing is on the rise. Most of the studies employing molecular tools were carried out in South Africa and Nigeria, with the predominant strain reported in South Africa being ST6. In order to provide a better understanding of the importance of listeria in Africa, there is the need for extensive and coordinated studies using modern molecular-based techniques to characterize the various Listeria species, and to assess the disease epidemiology using the one health concept. [ABSTRACT FROM AUTHOR]

Listeriosis is a zoonotic disease caused by Listeria monocytogenes and Listeria ivanovii. The genus Listeria currently includes 27 recognized species and is found throughout the environment. The number of systematic studies on antimicrobial resistance in L. monocytogenes isolates from domestic farms using antimicrobial substances is limited. Importantly, dairy ruminant farms are reservoir of hypervirulent lineage I L. monocytogenes isolates, previously associated with human clinical cases. Considering that the classes of antibiotics used in food-producing domestic animals are frequently the same or closely related to those used in human medicine, studies about the impact of antibiotic use on the acquisition of antibiotic resistance in Listeria spp. in domestic animal farms are, therefore, of high importance. Here, susceptibility to 25 antibiotics was determined. Eighty-one animal-related, 35 food and 21 human pathogenic Listeria spp. isolates and 114 animal-related non-pathogenic Listeria spp. isolates were tested. Whole genome sequencing data was used for molecular characterization. Regarding L. monocytogenes , 2 strains from the clinical-associated linage I showed resistance to erythromycin, both related to dairy ruminants. Acquired resistance to one antibiotic was exhibited in 1.5% of L. monocytogenes isolates compared with 14% of non-pathogenic Listeria spp. isolates. Resistance to tetracycline (7.9%), doxycycline (7.9%), penicillin (4.4%), and ampicillin (4.4%) were the most frequently observed in non-pathogenic Listeria spp. While resistance to two or more antibiotics (5.6%) was most common in Listeria spp., isolates, resistance to one antibiotic was also observed (1.6%). The present results show that non-pathogenic Listeria spp. harbour antimicrobial resistance genes. • Antibiotic resistance in Listeria monocytogenes isolates is infrequent (1.5%). • Antibiotic-resistant L. monocytogenes were only detected in animal sources. • L. monocytogenes from food or human sources showed no antibiotic resistance. • Non-pathogenic Listeria spp. showed a higher prevalence of resistance (14%). • MIC values of relevant antibiotics differ between L. monocytogenes lineage I and II. [ABSTRACT FROM AUTHOR]

In tropical countries, land snails are an important food source; however, foodborne disease risks are poorly quantified. We detected Campylobacter spp., Yersinia spp., Listeria spp., Salmonella spp., or Shiga-toxigenic Escherichia coli in 57%-86% of snails in Cameroon. Snail meat is a likely vector for enteric diseases in sub-Saharan Africa countries. [ABSTRACT FROM AUTHOR]

The catfish industry is important to the United States economy. The present study determined the levels of microbial indicators and the prevalence of Listeria spp. and Listeria monocytogenes at catfish farms and catfish processing plants. Live fish, water, and sediment samples were analyzed in farms. Fish skin, fillets, chiller water, and environmental surfaces were assessed at the processing plants both during operation and after sanitation. Live fish had 2% prevalence of Listeria monocytogenes, while sediment and water were negative for Listeria. Live fish skin counts averaged 4.2, 1.9, and 1.3 log CFU/cm2 aerobic (APC), total coliform (TCC) and generic Escherichia coli counts, respectively. Water and sediment samples averaged 4.8 and 5.8 log CFU/g APC, 1.9 and 2.3 log CFU/g TCC, and 1.0 and 1.6 log CFU/g generic E. coli counts, respectively. During operation, Listeria prevalence was higher in fillets before (57%) and after (97%) chilling than on fish skin (10%). Process chiller water had higher (p ≤ 0.05) APC, TCC, and Listeria prevalence than clean chiller water. After sanitation, most sampling points in which Listeria spp. were present had high levels of APC (>2.4 log CFU/100 cm2). APC combined with Listeria spp. could be a good approach to understand microbial contamination in catfish plants.

In this study, the effects of heat stress on titratable acidity ( 0 SH), fat, protein, dry matter, ash content and total aerobic mesophilic bacteria (TAMB), yeast and mold, micrococcus/staphylococcus, and coliform bacteria count of bulk tank milk in the milk collection center were investigated, and 156 cow's milk belonging to the Holstein breed was analyzed for three years (2011-2103), once a week. Temperature-humidity index (THI) was used to determine heat stress, and THic>70 was evaluated as heat stress. THic>70 is seen in June-September in 2011 and 2012, and in June-August in 2013. THI values of the day one day before sampling were taken into account when conducting the analysis. It was concluded that the effect of THI on the protein and ash content, the quantity of TAMB, yeast and mold, micrococcus/staphylococcus and coliform counts of milk was significant at the level of P:S0.001; also its effect on the dry matter was significant at the level of P:S0.05. It was found that when THl<50, the 0 SH, ash content of milk, TAMB, yeast and mold, micrococcus/staphylococcus and coliform counts were minimal, it reached maximum values when THic::70. The correlation between THI and 0 SH, milk ash content, TAMB, yeast and mold, micrococcus/staphylococcus and coliform counts was positive and the correlation between THI and milk fat, protein, and dry content was negative. The importance of the correlation was found to be P:S0.001 for 0 SH, protein and ash content of milk, and the quantity ofTAMB, yeast and mold, micrococcus/staphylococcus and coliform found to be P>0.05 for the contentoffatanddrymatter. The number of positive samples for Listeria spp. and Salmonella spp. was determined as 31 (19.87%) and 28 (17.95%), respectively. [ABSTRACT FROM AUTHOR]

L. monocytogenes is a public health threat linked to fast foods such as broiler chickens. This study aimed to verify the occurrence of Listeria species in chickens from abattoirs and evaluate their antimicrobial resistance. In total, 150 broiler carcass swabs distributed as cloacal (n = 60), exterior surface (n = 60), and environmental (n = 30) were collected. Listeria species were characterized using biochemical tests and PCR. We conducted antibiotic resistance tests using the disc diffusion and Etest (Biomerieux, Durham, NC, USA) methods. Overall isolation of Listeria species was 15% (23/150) 95% CI (10.16–22.33), 2% (3/150) 95% CI (0.52–6.19) and 13% (20/150) 95% CI (8.53–20.08) came from environmental swabs and carcass swabs, respectively. Proportions of positive Listeria isolates were L. monocytogenes 74% (17/23), L. welshimeri 22% (5/23), and L. innocua 4% (1/23). Listeria species from the exterior carcass swabs was 61% (14/23), cloacal swabs 26% (6/23), and environmental swabs 3% (3/23). L. monocytogenes had the greatest resistance percentage to the following antibiotics: clindamycin (61%, 10/23), tetracycline 30% (7/23), and erythromycin 13%, (3/23). Isolation of L. monocytogenes in relatively high numbers, including the antimicrobial profiles, suggests a potential risk of the pathogen remaining viable in the food continuum and a public health risk to would-be consumers.

Several outbreaks of L. monocytogenes have been involved with milk and dairy products consumption. The present study was conducted to investigate the prevalence listeria monocytogenes in raw milk and some dairy products. A total of 225 samples of raw milk (75), pasteurized milk (50), ice cream (50) and Ras cheese (50) were collected randomly from different supermarkets, retail outlets and other markets outlets in Damanhour city, El-Behira governorate, Egypt. Out of 225 samples, 29 (12.88%) were positive for Listeria species. The occurrence of Listeria spp. in raw milk, pasteurized milk, ice cream and Ras cheese samples were 10 (13.33%), 6 (12%), 7 (14%) and 6 (12%), respectively. The most prevalent listeria species isolated from raw milk and dairy products in this study was L. innocua and L. monocytogenes. The biochemically identified isolates of L. monocytogenes (16) were molecularly characterized by multiplex PCR for detection of three virulence genes (iap, hylA and actA); the results showed that iap gene was demonstrated in all isolates (100%); hylA and actA were detected in 83.3 and 66.7% of isolates from raw milk; 66.7 and 66.7% of isolates from pasteurized milk; 80 and 80% of isolates from ice cream; 100 and 50% of isolated from Ras cheese samples. Concerning to antibiotic resistance, 16 isolates of L. monocytogenes were tested against 14 antibiotics disc and showed that all the isolates were resistant to Kanamycin (100%) and Nalidixic acid (93.75%), meanwhile, most of the isolates showed sensitivity against Ciprofloxacin (87.50%) and Ampicillin (68.75%). In conclusion, the results of this study emphasize the need for applying more strict hygienic control measures especially during processing, storage and marketing of dairy products. [ABSTRACT FROM AUTHOR]

Small- and medium-sized dairy processing facilities (SMDFs) may face unique challenges with respect to controlling Listeria in their processing environments, e.g., due to limited resources. The aim of this study was to implement and evaluate environmental monitoring programs (EMPs) for Listeria control in eight SMDFs in a ∼1-year longitudinal study; this included a comparison of pre-operation (i.e., after cleaning and sanitation and prior to production) and mid-operation (i.e., at least 4 h into production) sampling strategies. Among 2,072 environmental sponge samples collected across all facilities, 272 (13%) were positive for Listeria. Listeria prevalence among pre- and mid-operation samples (15% and 17%, respectively), was not significantly different. Whole genome sequencing (WGS) performed on select isolates to characterize Listeria persistence patterns revealed repeated isolation of closely related Listeria isolates (i.e., ≤20 high-quality single nucleotide polymorphism [hqSNP] differences) in 5/8 facilities over >6 months, suggesting Listeria persistence and/or reintroduction was relatively common among the SMDFs evaluated here. WGS furthermore showed that for 41 sites where samples collected pre- and mid-operation were positive for Listeria, Listeria isolates obtained were highly related (i.e., ≤10 hqSNP differences), suggesting that pre-operation sampling alone may be sufficient and more effective for detecting sites of Listeria persistence. Importantly, our data also showed that only 1/8 of facilities showed a significant decrease in Listeria prevalence over 1 year, indicating continued challenges with Listeria control in at least some SMDFs. We conclude that options for simplified Listeria EMPs (e.g., with a focus on pre-operation sampling, which allows for more rapid identification of likely persistence sites) may be valuable for improved Listeria control in SMDFs., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Martin Wiedmann is a paid consultant for Neogen Corporation. All other coauthors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Hygiene practices in food processing plants are important determinants of food quality and safety. Poor hygiene practices may result in the contamination of foods and food products with pathogens, which means a serious risk to public health. This study was aimed at isolating and determining the antibacterial susceptibility profile of Listeria spp. and Staphylococcus aureus from smoked fish sold within Ahmadu Bello University Main Campus. A total of twenty-five (25) smoked fish samples were collected. Fifteen (15) samples, five each from Community market, Akenzua market and ICSA Ramat market were processed and inoculated on Mannitol Salt Agar for the isolation of Staphylococcus aureus. The remaining ten (10) samples were processed using stomacher and on Listeria Selective Agar (Oxford formulation) for the isolation of Listeria spp. The isolates were characterized based on their colonial morphology, Gram’s and biochemical reactions. In addition, agglutination test was carried out to further identify Listeria spp. Antibacterial susceptibility patterns of the isolates was determined using disc diffusion method. Staphylococcus aureus was isolated from all the 15 samples analyzed, giving an occurrence of 100%. However, only one Listeria spp. (Listeria ivanovii) was isolated from the 10 samples analyzed, with a 10% occurrence. All the S. aureus isolates were susceptible to most of the antibiotics, but four were resistant to rocephin and eight to ampiclox. The Listeria ivanovii isolate was also resistant to most of the antibiotics and susceptible to only two. The Multiple Antibiotics Resistance Index (MARI) of S. aureus isolates ranges from 0.2 to 0.4 while it was 0.75 for the Listeria ivanovii isolate. The study demonstrated that smoked fish sold in Ahmadu Bello University Main Campus were found to be contaminated and its consumption is potentially regarded as a health hazard, as such measures should be adopted to control it.

In this study the effect of the application of High Pressure Treatment (HPP) combined with four different manufacturing processes on the inactivation of Listeria innocua, used as a surrogate for L. monocytogenes, in artificially contaminated coppa samples was evaluated in order to verify the most suitable strategy to meet the Listeria inactivation requirements needed for the exportation of dry-cured meat in the U.S. Fresh anatomical cuts intended for coppa production were supplied by four different delicatessen factories located in Northern Italy. Raw meat underwent experimental contamination with Listeria innocua using a mixture of 5 strains. Surface contamination of the fresh anatomical cuts was carried out by immersion into inoculum containing Listeria spp. The conditions of the HPP treatment were: pressure 593 MPa, time 290 seconds, water treatment temperature 14°C. Listeria innocua was enumerated on surface and deep samples post contamination, resting, ripening and HPP treatment. The results of this study show how the reduction of the microbial load on coppa during the production process did not vary among three companies (P>0.05) ranging from 3.73 to 4.30 log CFU/g, while it was significantly different (P

In this study, the presence of Listeria monocytogenes in raw milk and milk products produced from raw milk by traditional method, such as cheese and butter using cultural and molecular techniques and the antibiotic resistances were investigated. Isolation was performed using the FDA technique. Microbact 12L test kit was used for biochemical identification. Genotyping of isolates was done by traditional PCR method. Antibiotic resistance of isolates was determined by standard disk diffusion method. Listeria spp. was detected in 16 (5.3%) of the total 300 food samples according to the biochemical identification results. The highest prevalence of Listeria spp. was in raw milk samples (10%), followed by cheese samples (4%) and butter samples (2%). All 36 Listeria spp. isolates which were obtained from biochemical identification were tested for L. monocytogenes by PCR, and 15 (41.6%) of them were confirmed as L. monocytogenes. According to the antibiotic resistance test results of L. monocytogenes strains, four (26.7%) isolates were resistant to at least one antibiotic while only one (6.7%) had multiple antibiotic resistance. The highest resistance was found against trimethoprim-sulfamethoxazole. It has been determined that L. monocytogenes isolates had the same degree resistance against penicillin G, meropenem, amikacin and vancomycin. In conclusion, the presence of L. monocytogenes which has been detected in dairy products made from raw milk and in raw milk itself may constitute a potential risk for public health. Furthermore, it is threatening for public health that the isolates obtained are resistant to certain antibiotics.

The main microbiological hazards of raw milk cheese are associated with Listeria monocytogenes, Escherichia coli and Staphylococcus aureus. Due to its high nutritional value, cheese is an excellent medium for the growth of these pathogens. This study was aimed to observe microbial dynamics of Bulgarian white brined cheese during cheese production and ripening. Microbiological analysis included determination of Staphylococcus aureus, Listeria spp. and Escherichia coli counts. Some physicochemical parameters, such as total titratable acidity, sodium chloride content, water activity and pH were also examined. Results revealed statistically significant increase in bacterial counts after cheesemaking steps and decrease at the end of the ripening period. Listeria monocytogenes was not detected in any of the cheese samples. Raw milk cheese was of unsatisfactory quality that emphasises the need for applying and maintaining good hygiene practices along the food chain to prevent microbial contamination and growth. [ABSTRACT FROM AUTHOR]

Lake Van is not a very convenient environment for life of both sea and freshwater fish due to its high alkaline (pH 9.8) and salty (0.21%) water and only pearl mullet (Chalcalburnus tarichi, Pallas 1811) are present in the lake. In this study, the presence and prevalence of Listeria species in samples of the pearl mullet (Chalcalburnus tarichi, Pallas 1811) living as an endemic species in Lake Van and taken from the market a total of 160 times for 12 months were examined. The method recommended by the United States Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) was used for the isolation and identification of Listeria species. Among the pearl mullet samples examined, Listeria spp. were isolated in 20 (12.50%) and of them L. innocua in 10 (6.25%) and L. welshimeri in 8 (5.00%) and L. ivanovii in 2 (1.25%) were identified. In this study, the presence of Listeria species in pearl mullet samples examined according to the seasons was revealed for the first time. Failure to identification of L. monocytogenes in any of the samples that is an important pathogen for humans, was assessed as an indicator that these fish did not constitute a public health risk in terms of listeriosis. As a result, Listeria spp. and other pathogenic microorganisms not to pose a risk to public health and in order to prevent the deterioration of fishes and reduce the economic losses, the transportation, storage and marketing of the caught fishes should be done under hygienic and cold conditions. [ABSTRACT FROM AUTHOR]

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Microorganisms in processing environments significantly impact the quality and safety of food products and can serve as potential reservoirs for antibiotic-resistant genes, contributing to public health concerns about antimicrobial resistance (AMR). Fish processing plants represent an understudied environment for microbiome mapping. This study investigated the microbial composition, prevalence of Listeria spp., and resistome structures in three catfish processing facilities in the southeastern United States. The 16S rRNA gene sequencing revealed that the observed richness and Shannon diversity index increased significantly from fish to fillet. Beta diversity analysis showed distinct clustering of microbial communities between fish, environment, and fillet samples. Fast expectation-maximization microbial source tracking (FEAST) algorithm demonstrated that the microbiota presents in the processing environment contributed 48.2 %, 62.4 %, and 53.7 % to the microbiota present on fillet in Facility 1 (F1), F2, and F3, respectively. Food contact surfaces made larger contributions compared to the non-food contact surfaces. The linear discriminant analysis of effect size (LEfSe) identified specific microbial genera (e.g., Plesiomohas, Brochothrix , Chryseobacterium and Cetobacterium) that significantly varied between Listeria spp. positive and negative samples in all three processing plants. The metagenomic sequencing results identified 212 antimicrobial resistance genes (ARGs) belonging to 72 groups from the raw fish and fish fillet samples collected from three processing plants. Although there was a significant decrease in the overall diversity of ARGs from fish to fillet samples, the total abundance of ARGs did not change significantly (P > 0.05). ARGs associated with resistance to macrolide-lincosamide-streptogramin (MLS), cationic antimicrobial peptides, aminoglycosides, and beta-lactams were found to be enriched in the fillet samples when compared to fish samples. Results of this study highlight the profound impact of processing environment on shaping the microbial populations present on the final fish product and the need for additional strategies to mitigate AMR in fish products. • Microbiota in processing environment contributed up to 62.4 %, of fillet microbiota. • Food contact surfaces (FCS) impact the microbiota in fillets more than non-FCS. • Plesiomohas, and Brochothrix were more abundant in Listeria positive samples. • Chryseobacterium and Cetobacterium were more abundant in Listeria negative samples. • The richness of the AMR increased while the total abundance remained unchanged. [ABSTRACT FROM AUTHOR]

Bacterial contamination in food-processing facilities is a critical issue that leads to outbreaks compromising the integrity of the food supply and public health. We developed a label-free and rapid electrochemical biosensor for Listeria monocytogenes detection using a new one-step simultaneous sonoelectrodeposition of platinum and chitosan (CHI/Pt) to create a biomimetic nanostructure that actuates under pH changes. The XPS analysis shows the effective co-deposition of chitosan and platinum on the electrode surface. This deposition was optimized to enhance the electroactive surface area by 11 times compared with a bare platinum–iridium electrode (p < 0.05). Electrochemical behavior during chitosan actuation (pH-stimulated osmotic swelling) was characterized with three different redox probes (positive, neutral, and negative charge) above and below the isoelectric point of chitosan. These results showed that using a negatively charged redox probe led to the highest electroactive surface area, corroborating previous studies of stimulus–response polymers on metal electrodes. Following this material characterization, CHI/Pt brushes were functionalized with aptamers selective for L. monocytogenes capture. These aptasensors were functional at concentrations up to 106 CFU/mL with no preconcentration nor extraneous reagent addition. Selectivity was assessed in the presence of other Gram-positive bacteria (Staphylococcus aureus) and with a food product (chicken broth). Actuation led to improved L. monocytogenes detection with a low limit of detection (33 CFU/10 mL in chicken broth). The aptasensor developed herein offers a simple fabrication procedure with only one-step deposition followed by functionalization and rapid L. monocytogenes detection, with 15 min bacteria capture and 2 min sensing.