scholarly journals Listeria monocytogenes: An emerging food-borne pathogen and its public health implications

2016 ◽  
Vol 10 (02) ◽  
pp. 149-154 ◽  
Author(s):  
Waffa W Reda ◽  
Khaled Abdel-Moein ◽  
Ahmed Hegazi ◽  
Yasmin Mohamed ◽  
Khaled Abdel-Razik
Keyword(s):  
Listeria Monocytogenes ◽  
Raw Milk ◽  
Food Samples ◽  
Food Borne ◽  
Contaminated Food ◽  
Luncheon Meat ◽  
Stool Specimens ◽  
Polymerase Chain ◽  
Minced Meat

Introduction: Listeria monocytogenes is considered one of the most important food-borne pathogens transmitted to humans via contaminated food. The aim of the present study was to demonstrate the importance of L. monocytogenes as a food-borne pathogen. Methodology: A total of 340 samples were collected from different localities in El Giza Governorate, Egypt, to check the occurrence of L. monocytogenes in that area. The collected samples comprised 250 food samples, 40 swabs from food refrigerators, and 50 stool specimens from diarrheic children. L. monocytogenes was isolated from the examined samples according to the International Organization for Standardization. The isolates were tested biochemically using Listeria Microbact 12L and confirmed by polymerase chain reaction. Results: The isolation rates of L. monocytogenes were 8% in beef burger, 4% in minced meat, 4% in luncheon meat, while sausage samples were all negative. Eight percent of raw milk samples were positive for L. monocytogenes, whereas cheese samples and refrigerator swabs were negative. Only Listeria grayi was isolated from human stools (2.5%). Conclusion: The high isolation rates of L. monocytogenes among the examined food stuffs highlight the crucial role of food as an important vehicle for this pathogen. More efforts should be made to ensure safe handling and processing of these foods to reduce the transmission of L. monocytogenes to humans.

scholarly journals Prevalence, Antibiogram and Genetic Characterization of Listeria monocytogenes from Food Products in Egypt

Foods ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1381
Author(s):  
Eman E. Abdeen ◽  
Walid S. Mousa ◽  
Ola. H. Harb ◽  
Gehad A. Fath-Elbab ◽  
Mohammed Nooruzzaman ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Genetic Characterization ◽  
Food Products ◽  
Raw Milk ◽  
Food Samples ◽  
World Health ◽  
Fish Fillet ◽  
Minced Meat ◽  
The Impact

World Health Organization classified Listeria monocytogenes as a major notable foodborne pathogen associated with high mortality and hospitalization. The study reports the prevalence, antibiogram, virulence determination and genetic characterization of L. monocytogenes from different food products. A total of 250 food samples, fifty samples each from raw milk, ice cream, minced meat, fish fillet and sausage were collected from the Menoufiya governorate in Egypt. L. monocytogenes was detected in 17 (6.8%) of the tested food samples including minced meat (14%), fish fillet (8%), sausage (6%) and raw milk (6%). The antimicrobial susceptibility assay of 17 L. monocytogenes isolates against seventeen antibiotics belonging to eight antibiotics classes revealed a high susceptibility to norfloxacin (82.3%), amoxicillin-clavulanic acid (76.4%), cefotaxime (70.5%), erythromycin (64.6%), amoxicillin (64.6%), gentamicin (58.7%) and vancomycin (58.7%). While, high resistance was observed against oxytetracycline (76.4%), trimethoprim-sulfamethoxazole (76.4%), chloramphenicol (70.5%), doxycycline (64.6%), levofloxacin (41.2%) and azithromycin (41.2%). Of note, all L. monocytogenes isolates were multidrug-resistant. The multiplex PCR successfully amplified L. monocytogenes in all tested isolates. Screening of the five virulence-related genes revealed the hlyA and iap as the most prevalent genes followed by actA gene, however, the inlA and prfA genes were not detected in any of the studied isolates. The partial 16S rRNA gene sequencing of three L. monocytogenes isolates showed a high nucleotide similarity (99.1–99.8%) between the study isolates and various global clones, and phylogenetic analysis clustered these L. monocytogenes strains with other Listeria species including L. welshimeri, L. seeligeri and L. innocua. This study demonstrates the impact of L. monocytogenes as a major contaminant of various food products and suggests more attention to the awareness and hygienic measures in the food industry.

Incidence and Polymerase Chain Reaction Assay of Listeria monocytogenes from Raw Milk in Gyeongnam Province of Korea

2002 ◽  
Vol 65 (1) ◽  
pp. 111-115 ◽  
Author(s):  
KWANG-SOO HA ◽  
SEON-JA PARK ◽  
SOOK-JAE SEO ◽  
JUNG-HYUN PARK ◽  
DUCK-HWA CHUNG
Keyword(s):  
Polymerase Chain Reaction ◽  
Listeria Monocytogenes ◽  
Raw Milk ◽  
Food Samples ◽  
Chain Reaction ◽  
Pcr Assay ◽  
Biochemical Tests ◽  
Milk Samples ◽  
Polymerase Chain ◽  
Pcr Assays

A total of 50 raw milk samples from Gyeongnam Province of Korea were examined for the incidence of Listeria monocytogenes between July 1998 and August 1998. L. monocytogenes isolated by biochemical test was confirmed by polymerase chain reaction (PCR) with two sets of primers designed from the invasion-associated protein (iap) gene. After standard PCR with external primers, the amplified DNA was confirmed by a second round of PCR with internal primers (nested PCR). Both the external and internal primers generated 468-bp and 287-bp products, respectively. Only one (G9 strain) of the three suspect samples that tested positive in biochemical tests for L. monocytogenes from 50 raw milk samples was also PCR positive. Following this procedure, PCR-positive G9 strain was confirmed by Southern blot using the 287-bp internal iap probe again. The detection limit of G9 strain by standard PCR assay was as few as 102 cells, equivalent to approximately 1 pg of L. monocytogenes DNA. These PCR assays may be useful for novel detection as well as rapid confirmation for L. monocytogenes from food samples and the field.

Commercial Latex Agglutination Kits for the Detection of Food borne Salmonella

1991 ◽  
Vol 54 (9) ◽  
pp. 725-730 ◽  
Author(s):  
J.-Y. D'AOUST ◽  
A. M. SEWELL ◽  
P. GRECO
Keyword(s):  
Food Samples ◽  
Latex Agglutination ◽  
Clinical Samples ◽  
Salmonella Spp ◽  
Concurrent Use ◽  
Food Borne ◽  
Analytical Test ◽  
Contaminated Food ◽  
Pure Cultures ◽  
Vi Antigen

The ability of the Bactigen® Salmonella Shigella (BSST), the Microscreen® (MS), and the Spectate® (SPECT) latex agglutination kits to detect Salmonella in pure cultures and in naturally contaminated foods was examined. Of 190 Salmonella strains tested, the MS, BSST, and SPECT systems correctly identified 89.5, 81.6, and 66.3% of the test cultures, respectively. The sensitivity of SPECT increased to 92.7% when only strains belonging to the targeted serogroups (somatic A to E plus G) and strains harboring the Vi antigen were considered. The lack of specificity of the MS (3.4%), SPECT (17.0%), and BSST (33.9%) systems with 59 cultures of nonsalmonellae varied widely, with Citrobacter freundii and Escherichia coli accounting for many of the false-positive reactions. Examination of foods according to the prescribed MS and SPECT analytical test protocols identified respectively, 18 (75%) and 19 (79.2%) of the 24 food samples found to contain Salmonella spp. by a standard cultural method. Although instructions with the BSST kit indicate that the product is intended for the analysis of clinical samples, the system nevertheless identified 21 (87.5%) contaminated food samples under homologous MS and SPECT test conditions. The concurrent use of TBG43 with enrichment media recommended by kit manufactures enhanced the sensitivities of MS (83.3%), SPECT (91.7%), and BSST (91.7%). Attempts to effect greater method brevity through the application of latex kits at various stages of the standard cultural procedure were counterproductive.

Comparison of EB and Fraser Enrichment Broths for the Detection of Listeria spp. and Listeria monocytogenes in Raw-Milk Dairy Products and Environmental Samples

1996 ◽  
Vol 59 (11) ◽  
pp. 1172-1175 ◽  
Author(s):  
GEERTRUI M. VLAEMYNCK ◽  
RENAAT MOERMANS
Keyword(s):  
Listeria Monocytogenes ◽  
Dairy Products ◽  
Raw Milk ◽  
Chain Reaction ◽  
Enrichment Broth ◽  
Selective Enrichment ◽  
Isolation Frequency ◽  
Detection And Identification ◽  
Significant Difference ◽  
Polymerase Chain

This study is a comparison of the isolation frequency of Listeria spp. and Listeria monocytogenes from selected naturally contaminated dairy products, especially soft smear-ripened cheeses from raw milk and samples of feces and rinse samples from the udder taken on the farm, by using an enrichment broth (EB) recommended by the International Dairy Federation and the U.S. Food and Drug Administration (IDF and FDA) or Fraser broth as the selective enrichment. Detection and identification were carried out according to the IDF protocols and a polymerase chain reaction technique. Listeria spp. were detected in 39.8% of the 570 samples while 15.3% were positive for L. monocytogenes. For cheese and curd samples, Fraser enrichment broth gave a statistically significant higher recovery for all Listeria spp. (26 to 21 %) as well as for L. monocytogenes in particular (9 to 1.4%). For raw milk and samples taken from feces and the udder rinse no significant difference was found between EB and Fraser broth. A combination of both enrichments resulted in an increase of recovery over all matrices by 15%.

scholarly journals REALIS: Postgenomic Analysis ofListeria monocytogenes

2002 ◽  
Vol 3 (1) ◽  
pp. 32-34 ◽  
Author(s):  
Uwe Kärst ◽  
The REALIS Consortium
Keyword(s):  
Listeria Monocytogenes ◽  
Opportunistic Infections ◽  
External Environment ◽  
Low Ph ◽  
Health Care Managers ◽  
Food Borne ◽  
Contaminated Food ◽  
Oflisteria Monocytogenes ◽  
Immunocompromised Hosts ◽  
Host Tissues

Listeria monocytogenesis a remarkably successful food-borne pathogen. It is capable a) of surviving and proliferating under conditions that exist within the food chain, such as at low temperatures, high salt and low pH and b) of colonizing animal host tissues after ingestion of contaminated food, causing opportunistic infections mainly, but not exclusively, in immunocompromised hosts. The ultimate goals of REALIS are two fold: Firstly, it aims to completely decipher all genes required for survival in and adaptation ofListeria monocytogenesto two very different environments, ie., the infected host and the external environment. Secondly, using genomics and postgenomic tools, REALIS seeks to precisely address fundamental questions regarding evolutionary relationships between pathogenic and non-pathogenic Listeria and to define qualities of particularly successful clonal pathovariants in causing disease. This project will provide both industry and health care managers with rational approaches to curbing food-borne contamination, minimising risks of infection and providing novel pharmacological approaches for halting the fulminant course of infection.

scholarly journals Rapid detection of Listeria monocytogenes in raw milk and soft cheese by a redox potential measurement based method combined with real-time PCR

2014 ◽  
Vol 62 (3) ◽  
pp. 304-316 ◽  
Author(s):  
Orsolya Erdősi ◽  
Katalin Szakmár ◽  
Olivér Reichart ◽  
Zsuzsanna Szili ◽  
Noémi László ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Redox Potential ◽  
Real Time ◽  
Real Time Pcr ◽  
Rapid Detection ◽  
Raw Milk ◽  
Food Samples ◽  
Potential Measurement ◽  
Effective Manner ◽  
Soft Cheese

The incidence of outbreaks of foodborne listeriosis has indicated the need for a reliable and rapid detection of the microbe in different foodstuffs. A method combining redox potential measurement and real-time polymerase chain reaction (PCR) was developed to detectListeria monocytogenesin artificially contaminated raw milk and soft cheese. Food samples of 25 g or 25 ml were homogenised in 225 ml of Listeria Enrichment Broth (LEB) with Oxford supplement, and the redox potential measurement technique was applied. ForListeriaspecies the measuring time was maximum 34 h. The absence ofL. monocytogenescould reliably be proven by the redox potential measurement method, butListeria innocuaandBacillus subtiliscould not be differentiated fromL. monocytogeneson the basis of the redox curves. The presence ofL. monocytogeneshad to be confirmed by real-time PCR. The combination of these two methods proved to detect < 10 cfu/g ofL. monocytogenesin a cost- and time-effective manner. This method can potentially be used as an alternative to the standard nutrient method for the rapid detection ofL. monocytogenesin food.

scholarly journals Role of Extracellular DNA during Biofilm Formation by Listeria monocytogenes

2010 ◽  
Vol 76 (7) ◽  
pp. 2271-2279 ◽  
Author(s):  
Morten Harmsen ◽  
Martin Lappann ◽  
Susanne Kn�chel ◽  
S�ren Molin
Keyword(s):  
Listeria Monocytogenes ◽  
Biofilm Formation ◽  
Extracellular Dna ◽  
Central Component ◽  
High Molecular Weight Dna ◽  
Food Borne ◽  
Attachment Sites ◽  
Sperm Dna ◽  
Salmon Sperm Dna

ABSTRACT Listeria monocytogenes is a food-borne pathogen that is capable of living in harsh environments. It is believed to do this by forming biofilms, which are surface-associated multicellular structures encased in a self-produced matrix. In this paper we show that in L. monocytogenes extracellular DNA (eDNA) may be the only central component of the biofilm matrix and that it is necessary for both initial attachment and early biofilm formation for 41 L. monocytogenes strains that were tested. DNase I treatment resulted in dispersal of biofilms, not only in microtiter tray assays but also in flow cell biofilm assays. However, it was also demonstrated that in a culture without eDNA, neither Listeria genomic DNA nor salmon sperm DNA by itself could restore the capacity to adhere. A search for additional necessary components revealed that peptidoglycan (PG), specifically N-acetylglucosamine (NAG), interacted with the DNA in a manner which restored adhesion. If a short DNA fragment (less than approximately 500 bp long) was added to an eDNA-free culture prior to addition of genomic or salmon sperm DNA, adhesion was prevented, indicating that high-molecular-weight DNA is required for adhesion and that the number of attachment sites on the cell surface can be saturated.

Incidence and Characterization of Listeria monocytogenes from Domestic and Imported Foods in Korea

2000 ◽  
Vol 63 (2) ◽  
pp. 186-189 ◽  
Author(s):  
SUN-YOUNG BAEK ◽  
SOON-YOUNG LIM ◽  
DONG-HA LEE ◽  
KYUNG-HEE MIN ◽  
CHANG-MIN KIM
Keyword(s):  
Listeria Monocytogenes ◽  
Raw Milk ◽  
Listeriolysin O ◽  
Department Of Agriculture ◽  
Saltwater Fish ◽  
Serotype 1 ◽  
Imported Food ◽  
Polymerase Chain ◽  
Imported Foods

A total of 1,537 domestic and imported food products were examined for the incidence of Listeria monocytogenes between 1993 and 1997 in Korea. L. monocytogenes was detected using the U.S. Department of Agriculture isolation method. Isolated L. monocytogenes was confirmed by polymerase chain reaction with hly1 and hly2 primers designed from the listeriolysin O. Overall, 122 samples (7.9%) contained L. monocytogenes. The rate of isolation was 4.3% for beef, 19.1% for pork, 30.2% for chicken, 1.2% for shellfish, 4.4% for raw milk, 4.4% for frozen smoked mussels, and 6.1% for ice cream. No L. monocytogenes was found in pasteurized milk, pasteurized processed cheese, saltwater fish, dried seafoods, or ham. The overall incidence was lower than that reported in previous studies from other countries. Most isolates were serotype 1/2b except for chicken, in which serotype 1/2a was predominant. The serotyping results might imply the presence of food or geography-specific L. monocytogenes strains.

scholarly journals An outbreak of viral gastroenteritis associated with consumption of sandwiches: implications for the control of transmission by food handlers

1998 ◽  
Vol 121 (3) ◽  
pp. 615-621 ◽  
Author(s):  
U. D. PARASHAR ◽  
L. DOW ◽  
R. L. FANKHAUSER ◽  
C. D. HUMPHREY ◽  
J. MILLER ◽  
...  
Keyword(s):  
Food Handler ◽  
Common Source ◽  
Viral Gastroenteritis ◽  
Food Handlers ◽  
Rt Pcr ◽  
Source Of Infection ◽  
Food Borne ◽  
Pcr Product ◽  
Stool Specimens ◽  
Polymerase Chain

Although food handlers are often implicated as the source of infection in outbreaks of food-borne viral gastroenteritis, little is known about the timing of infectivity in relation to illness. We investigated a gastroenteritis outbreak among employees of a manufacturing company and found an association (RR=14·1, 95% CI=2·0–97·3) between disease and eating sandwiches prepared by 6 food handlers, 1 of whom reported gastroenteritis which had subsided 4 days earlier. Norwalk-like viruses were detected by electron microscopy or reverse transcriptase-polymerase chain reaction (RT-PCR) in stool specimens from several company employees, the sick food handler whose specimen was obtained 10 days after resolution of illness, and an asymptomatic food handler. All RT-PCR product sequences were identical, suggesting a common source of infection. These data support observations from recent volunteer studies that current recommendations to exclude food handlers from work for 48–72 h after recovery from illness may not always prevent transmission of Norwalk-like viruses because virus can be shed up to 10 days after illness or while exhibiting no symptoms.

Combination of Immunomagnetic Separation and Polymerase Chain Reaction for the Simultaneous Detection of Listeria monocytogenes and Salmonella spp. in Food Samples

2001 ◽  
Vol 64 (11) ◽  
pp. 1744-1750 ◽  
Author(s):  
HSIEN-YEE HSIH ◽  
HAU-YANG TSEN
Keyword(s):  
Polymerase Chain Reaction ◽  
Listeria Monocytogenes ◽  
Simultaneous Detection ◽  
Meat Products ◽  
Immunomagnetic Separation ◽  
Food Samples ◽  
Chain Reaction ◽  
Salmonella Spp ◽  
Pcr Method ◽  
Polymerase Chain

A method that combined the immunomagnetic separation (IMS) technique and the multiplex polymerase chain reaction (PCR) method (i.e., the IMS-mPCR method) was developed for simultaneous detection of Listeria monocytogenes and Salmonella spp. in food samples. When only the multiplex PCR method was used, it was found that if cell numbers of each of the two target organisms (L. monocytogenes and Salmonella spp.) were above the detection limit, but differed by more than 2 logs—e.g., n × 107 to n × 104 or n × 106 to n × 103—the organism presenting the lower numbers might go undetected. Following the enrichment step with universal preenrichment (UP) broth, if an IMS method using equal quantities of anti-Listeria and anti-Salmonella immunomagnetic beads was performed prior to PCR, both pathogens could be detected unambiguously. Such results could be obtained for target organisms in food samples, such as milk, dairy, and meat products, if similar enrichment and IMS steps were performed prior to PCR.

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