Survival and growth behaviour of Listeria monocytogenes in ready-to-eat vegetable salads

Alegbeleye, Oluwadara Oluwaseun; Sant’Ana, Anderson S.

doi:10.1016/j.foodcont.2022.109023

Cited by 20 publications

(11 citation statements)

References 80 publications

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“…Listeria monocytogenes is the etiological agent of listeriosis disease in both humans and animals. The ubiquitous character of the bacterium makes it widespread in both the natural environment and the food processing environment, thus easily contaminating fresh produce (e.g., fruits and vegetables) [ 1 , 2 , 3 , 4 , 5 ] and foods of animal origin (e.g., meat and dairy products) [ 6 , 7 , 8 , 9 ]. Listeriosis is a serious infectious disease with one of the highest case fatality rates in humans ( ca.…”

Section: Introductionmentioning

confidence: 99%

Characterization and Antibiotic Resistance of Listeria monocytogenes Strains Isolated from Greek Myzithra Soft Whey Cheese and Related Food Processing Surfaces over Two-and-a-Half Years of Safety Monitoring in a Cheese Processing Facility

Andritsos

Mataragas²

2023

Foods

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Listeriosis is a serious infectious disease with one of the highest case fatality rates (ca. 20%) among the diseases manifested from bacterial foodborne pathogens in humans, while dairy products are often implicated as sources of human infection with Listeria monocytogenes. In this study, we characterized phenotypically and genetically by whole-genome sequencing (WGS) 54 L. monocytogenes strains isolated from Myzithra, a traditional Greek soft whey cheese (48 isolates), and swabs collected from surfaces of a cheese processing plant (six isolates) in the Epirus region of Greece. All but one strain of L. monocytogenes belonged to the polymerase chain reaction (PCR) serogroups IIa (16.7%) and IIb (81.5%), corresponding to serotypes 1/2a, 3a and 1/2b, 3b, 7, respectively. The latter was identified as a PCR-serogroup IVb strain (1.8%) of serotypes 4b, 4d, 4e. Bioinformatics analysis revealed the presence of five sequence types (STs) and clonal complexes (CCs); ST1, ST3, ST121, ST 155, ST398 and CC1, CC3, CC121, CC155, CC398 were thus detected in 1.9, 83.3, 11.0, 1.9, and 1.9% of the L. monocytogenes isolates, respectively. Antibiograms of the pathogen against a panel of seven selected antibiotics (erythromycin, tetracycline, benzylpenicillin, trimethoprim-sulfamethoxazole, ampicillin, ciprofloxacin, and meropenem) showed that 50 strains (92.6%), the six surface isolates also included, were intermediately resistant to ciprofloxacin and susceptible to the rest of the six antimicrobial agents tested, whereas strong resistance against the use of a single from three implicated antibiotics was recorded to four strains (7.4%) of the pathogen isolated from Myzithra cheese samples. Thence, the minimum inhibitory concentrations (MICs) were determined for erythromycin (MIC = 0.19 μg/mL), ciprofloxacin (MIC ≥ 0.19 μg/mL), and meropenem (MIC = 0.64 μg/mL), and finally, just one strain was deemed resistant to the latter antibiotic. The phylogenetic positions of the L. monocytogenes strains and their genetic variability were determined through WGS, whilst also stress response and virulence gene analysis for the isolates was conducted. Findings of this work should be useful as they could be utilized for epidemiological investigations of L. monocytogenes in the food processing environment, revealing possible contamination scenarios, and acquired antimicrobial resistance along the food production chain.

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Section: Introductionmentioning

confidence: 99%

Characterization and Antibiotic Resistance of Listeria monocytogenes Strains Isolated from Greek Myzithra Soft Whey Cheese and Related Food Processing Surfaces over Two-and-a-Half Years of Safety Monitoring in a Cheese Processing Facility

Andritsos

Mataragas²

2023

Foods

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“…The water activity (aw) of ready-to-use vegetable salad samples was between 0.873 and 0.933 (Figure 1), with values slightly lower than those reported by other studies. Zhang et al [37] reported water activity being between 0.97 and 0.99 for ready-to-use vegetables, while Alegbeleye and Sant'Ana [38] obtained the aw as being between 0.95 and 0.99 for ready-to-use vegetable salads.…”

Section: Resultsmentioning

confidence: 99%

Ready-to-Use Vegetable Salads: Physicochemical and Microbiological Evaluation

Albu,

Prisacaru,

Ghinea

et al. 2024

Applied Sciences

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Ready-to-use vegetable salads are minimally processed products, rich in antioxidants, but are associated with a high microbiological risk and possibly, in some cases, with a high content of nitrites. The purpose of this study was to investigate the physicochemical and microbiological properties of different ready-to-use vegetable salad assortments on the Romanian market. Seventeen types of salad vegetables were evaluated for the determination of water activity, antioxidant activity and nitrite concentration and tested for the presence of microorganisms. The water activity of the samples varied from 0.873 to 0.933, and the IC50 values were between 1.31 ± 0.02 and 5.43 ± 0.04 µg/mL. Nitrites were present in all samples investigated (ranging from 290.6 to 3041.17 mg/kg). Staphylococci and Enterobacteriaceae were detected in 35.3% and 70.5% of the samples. Furthermore, 17.6% of the salads were contaminated with Escherichia coli, and Listeria was detected in 29.4% of the samples. Salmonella was detected in only one sample, and Faecal streptococci were not present in any of the samples. The results indicated high nitrite values and also revealed pathogens’ presence. Producers should make more efforts to lower microbial contamination, while maximum limits for nitrites in vegetables should be set based on the impact on human health.

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“…Leafy vegetables, which are often consumed raw, can be associated with outbreaks of foodborne pathogens such as Escherichia coli , Listeria, and Salmonella [ 1 , 2 ]. During postharvest processing, processors rely on cleaning and sanitizing methods to reduce the microbial load of the product, maintain its quality, extend its shelf life, and ensure its microbial safety [ 1 , [3] , [4] , [5] ]. Fresh-cut or ready-to-eat (RTE) vegetables are the fastest-growing segment in the vegetable industry today.…”

Section: Introductionmentioning

confidence: 99%

“…Essential oils (EOs) have been proven to be highly effective against various food microorganisms [ 21 , 22 ]. They are particularly effective in the vapor phase, as they can produce low-molecular-weight or volatile molecules [ 5 , [23] , [24] , [25] ]. In situations where direct contact is not possible, such as with large areas or products, Eos can still be effective.…”

Section: Introductionmentioning

confidence: 99%

Carvacrol and thymol effect in vapor phase on Escherichia coli and Salmonella serovar Typhimurium growth inoculated in a fresh salad

Cid-Pérez,

Munguía-Pérez,

Nevárez-Moorillón

et al. 2024

Heliyon

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Survival and growth behaviour of Listeria monocytogenes in ready-to-eat vegetable salads

Cited by 20 publications

References 80 publications

Characterization and Antibiotic Resistance of Listeria monocytogenes Strains Isolated from Greek Myzithra Soft Whey Cheese and Related Food Processing Surfaces over Two-and-a-Half Years of Safety Monitoring in a Cheese Processing Facility

Characterization and Antibiotic Resistance of Listeria monocytogenes Strains Isolated from Greek Myzithra Soft Whey Cheese and Related Food Processing Surfaces over Two-and-a-Half Years of Safety Monitoring in a Cheese Processing Facility

Ready-to-Use Vegetable Salads: Physicochemical and Microbiological Evaluation

Carvacrol and thymol effect in vapor phase on Escherichia coli and Salmonella serovar Typhimurium growth inoculated in a fresh salad

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