Virulence Characteristics and Distribution of the Pathogen Listeria Ivanovii in the Environment and in Food (original) (raw)
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2020
This study aimed to evaluate the hazards posed by foodborne bacteria of the Listeria genus by analyzing prevalence, diversity and virulence of Listeria spp. in food and food manufacturing plants. Seventy five isolates obtained from the routine analysis of 653 samples by three diagnostic laboratories in Northern Italy were genotipically differentiated by Repetitive Extragenic Palindrome (rep) PCR with the GTG5 primer, identified by sequencing the 16S rRNA gene and examined by specific PCR tests for the presence of L. monocytogenes virulence determinants occasionally found to occur in other species of the genus. The identity of the amplification products was confirmed by sequencing. Fifty seven isolates were identified as L. innocua, 12 as L. monocytogenes, 5 as L. welshimeri and one as L. seeligeri. All L. monocytogenes isolates belonged to the serotype 1/2a and were predicted to be virulent for the presence of the inlJ internalin gene. Potentially virulent strains of L. innocua, L. seeligeri and L. welshimeri, carrying the L. monocytogenes inlA gene and/or hly gene, were identified, and most isolates were found to possess the toxin-antitoxin system mazEF for efficient adaptation to heat shock. Results indicated the need to reinforce food contamination prevention measures against all Listeria species by efficiently defining their environmental distribution.
Microorganisms
This study evaluates the hazards posed by foodborne bacteria of the Listeria genus by analyzing the occurrence, diversity and virulence of Listeria spp.in food and food-manufacturing plants. Seventy-five isolates obtained from the routine analysis of 653 samples taken by three diagnostic laboratories in Northern Italy were genotypically differentiated by Repetitive Extragenic Palindrome (rep) PCR, with the GTG5 primer identified by sequencing the 16S rRNA gene and examined by specific PCR tests for the presence of L. monocytogenes virulence determinants occasionally found to occur in other species of the genus. Within this sample, 76% (n = 57) isolates were identified as L. innocua, 16% (n = 12) as L. monocytogenes, 6.6% (n = 5) as L. welshimeri and 1.3% (n = 1) as L. seeligeri. All L. monocytogenes isolates belonged to the serotype 1/2a and were predicted to be virulent for the presence of the inlJ internalin gene. Potentially virulent strains of L. innocua, L. seeligeri and L. wel...
Listeria monocytogenes Monographic Study
usab-tm.ro
Listeria monocytogenes is a ubiquitous bacteria with a remarkable resistance in discordant condition which produce listeriosis, an infectious disease that affects multiple domestic and wild animals' species, but also humans. Receptive to listeriosis are the majority of domestic or wild mammals and birds, in the last years being registered an increase of receptivity in humans. The concept of listeriosis in human pathology, a disease caused by eating or drinking contaminated food and water, appeared for the first time in 1981, during an outbreak in Canada with seven cases in adults and 34 cases of maternalfetal listeriosis. The alimentary origin of human listeriosis can be easily explained if considered some general characteristics of the bacteria. Thus, resistance in various conditions, especially at lower temperatures, justifies its dissemination and food contamination, particularly when is conserved by refrigeration. Also, L. monocytogenes has a significant presence in alimentary products. Some studies showed that 4% of the milk products, 29% of the meat products, 5% of the vegetable products and 26% of the products obtained from fishes and shell fishes are positive for L. monocytogenes, which allows us to say that battle against these bacteria is a war against microbial contamination.
This study aimed to evaluate the hazards posed by foodborne bacteria of the Listeria genus by analyzing prevalence, diversity and virulence of Listeria spp. in food and food manufacturing plants. Seventy five isolates obtained from the routine analysis of 653 samples by three diagnostic laboratories in Northern Italy were genotipically differentiated by Repetitive Extragenic Palindrome (rep) PCR with the GTG5 primer, identified by sequencing the 16S rRNA gene and examined by specific PCR tests for the presence of L. monocytogenes virulence determinants occasionally found to occur in other species of the genus. The identity of the amplification products was confirmed by sequencing. Fifty seven isolates were identified as L. innocua, 12 as L. monocytogenes, 5 as L. welshimeri and one as L. seeligeri. All L. monocytogenes isolates belonged to the serotype 1/2a and were predicted to be virulent for the presence of the inlJ internalin gene. Potentially virulent strains of L. innocua, L. ...
Food Microbiology, 2009
In this study, we examined Listeria monocytogenes isolates from Chinese food sources in an attempt to gain further insights on the molecular characteristics and virulence potential of this important foodborne pathogen. Of the 88 L. monocytogenes food isolates recovered, 42 (47.7%) were of serovars 1/2a or 3a; 23 (26.1%) of serovars 1/2b or 3b; 15 (17.0%) of 1/2c or 3c; 6 (6.8%) of serovars 4b, 4d or 4e; and 2 (2.2%) of serovars 4a or 4c. In contrast to inlAB locus conserved in all serovars, internalin cluster between ascB and dapE varies with different serovars, with inlC2DE, inlGC2DE and inlGHE predominantly in serovars 1/2b or 4b, serovar 1/2a and serovar 1/2c. While inlF existed in all the inlGHE-and inlGC2DE-containing isolates but 17.4% of those having inlC2DE, lmo2026 existed in all the inlGHE-containing isolates but 20.0% of those bearing inlGC2DE, suggesting that inlF might have co-evolved with inlGC2DE and inlGHE while lmo2026 with inlGHE only. With the exception of serovar 4a isolate, most serovar isolates demonstrated remarkable ability to form plaques on L929 cells and produced significant mouse mortality irrespective of the internalin gene organization and whether an intact actA gene is present or not. These results indicate that majority of these food isolates may have the potential to cause human diseases if ingested via contaminated foods. Given that serovar 4b accounts for nearly half of human clinical listeriosis cases documented, the relative low proportion of serovar 4b food isolates suggests that this serovar is probably more tolerant of the adverse conditions in the host's stomach and/or more efficient in entering host cells than serovars 1/2a, 1/2b and 1/2c.
FEMS Immunology & Medical Microbiology, 2005
We analyzed 27 Listeria monocytogenes strains of serotypes 1/2b and 4b, from invasive and gastroenteric listeriosis, for molecular and experimental virulence. Molecular virulence was tested by PCR for the presence of 8 major virulence-associated genes and genetic polymorphisms through restriction enzyme analysis; genomic DNA typing using pulsed-field gel electrophoresis was also performed. Experimental virulence was evaluated through intra-peritoneal and intra-gastric mouse virulence assays. Our results showed no significant differences in the virulence-related molecular properties of the strains analyzed. All strains were equally pathogenic following intra-peritoneal inoculation of mice. In mice inoculated intra-gastric with 4 representative strains of the 2 types of listeriosis, there were no significant differences in the bacterial count when comparing invasive and gastroenteric strains, suggesting that the strains were comparable in terms of mean oral infectivity.
Characterization of Listeria monocytogenes from food and food-related settings
international food research journal, 2016
Listeriosis is a serious public health concern due to its high fatality rates. The present investigation screened for the occurrence of Listeria monocytogenes in food and food-related environments by analyzing samples from a cheese making factory, a slaughterhouse and a supermarket. Among the eighty-seven samples analyzed, thirty-four isolates were recovered and subsequently evaluated regarding genomic diversity, antibiotic susceptibility and virulence. Twenty-one L. monocytogenes were allocated to serogroup 1/2a-3a, ten assigned to serogroup 4b-4e-4ab and three to serogroup 1/2c-3c. Results obtained also detected the presence of L. monocytogenes isolates resistant to two clinically relevant antibiotics for the treatment of listeriosis, ampicillin and penicillin. Overall, data gathered disclosed the occurrence of listeria isolates with high pathogenicity potential at all very distinct sampling sites, reinforcing the need for an effective surveillance network designed for detecting the presence of L. monocytogenes in food products and food processing environments.