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Microbial Genomics Jul 2022() is a bacterial pathogen that causes listeriosis in immunocompromised individuals, particularly pregnant women. Several virulence factors support the intracellular...
() is a bacterial pathogen that causes listeriosis in immunocompromised individuals, particularly pregnant women. Several virulence factors support the intracellular lifecycle of and facilitate cell-to-cell spread, allowing it to occupy multiple niches within the host and cross-protective barriers, including the placenta. One family of virulence factors, internalins, contributes to pathogenicity by inducing specific uptake and conferring tissue tropism. Over 25 internalins have been identified thus far, but only a few have been extensively studied. Internalins contain leucine-rich repeat (LRR) domains that enable protein-protein interactions, allowing to bind host proteins. Notably, other species express internalins but cannot colonize human hosts, prompting questions regarding the evolution of internalins within the genus . Internalin P (InlP) promotes placental colonization through interaction with the host protein afadin. Although prior studies of InlP have begun to elucidate its role in pathogenesis, there remains a lack of information regarding homologs in other species. Here, we have used a computational evolutionary approach to identify InlP homologs in additional species. We found that () and () encode InlP homologs. We also found InlP-like homologs in and the recently identified species . All newly identified homologs lack the full-length LRR6 and LRR7 domains found in 's InlP. These findings are informative regarding the evolution of one key virulence factor, InlP, and serve as a springboard for future evolutionary studies of pathogenesis as well as mechanistic studies of internalins.
Topics: Bacterial Proteins; Female; Humans; Listeria; Listeria monocytogenes; Listeriosis; Placenta; Pregnancy; Virulence Factors
PubMed: 35904424
DOI: 10.1099/mgen.0.000828 -
Food Microbiology Apr 2015The presence of multiple species of Listeria in regulated food products is not uncommon and can complicate the recovery of Listeria monocytogenes particularly on a...
The presence of multiple species of Listeria in regulated food products is not uncommon and can complicate the recovery of Listeria monocytogenes particularly on a non-differentiating medium. The potential complications of Listeria seeligeri and Listeria welshimeri on the recovery of L. monocytogenes from inoculated food test samples using the U.S. Food and Drug Administration's (FDA) selective enrichment procedure was investigated. Post-enrichment enumeration, in the absence of food product, indicates that some L. seeligeri and L. monocytogenes pairings may have population differentials as great as 2.7 ± 0.1 logs with L. seeligeri being the predominant species. A similar observation was noted for L. welshimeri and L. monocytogenes pairings which resulted in population differentials as large as 3.7 ± 0.2 logs with L. welshimeri being the predominant species. Select strain pairings were used to inoculate guacamole, crab meat, broccoli, and cheese with subsequent recovery by the FDA Bacteriological Analytical Manual (BAM) method with 10 colonies per sample selected for confirmation. The presence of L. seeligeri had little effect on the recovery of L. monocytogenes. The presence of L. welshimeri resulted in the failure to recover L. monocytogenes in three out of the four food matrices. This work extends the observation that non-pathogenic species of Listeria can complicate the recovery of L. monocytogenes and that competition during selective enrichment is not limited to the presence of just Listeria innocua.
Topics: Food Contamination; Food Microbiology; Listeria; Listeria monocytogenes
PubMed: 25475325
DOI: 10.1016/j.fm.2014.09.008 -
Prevalence and contamination levels of Listeria monocytogenes in smoked fish and pâté sold in Spain.Journal of Food Protection Dec 2001From March to November 2000, 170 samples of smoked fish and 182 samples of pâté for sale in retail outlets and supermarkets in the nine provinces of Castilla and León...
From March to November 2000, 170 samples of smoked fish and 182 samples of pâté for sale in retail outlets and supermarkets in the nine provinces of Castilla and León (Spain) were analyzed for the prevalence of Listeria monocytogenes and other Listeria spp. L. monocytogenes was isolated from 38 (22.3%) of the 170 samples of smoked fish analyzed. Twenty of these positive samples contained L. monocytogenes at >100 CFU/g. Other Listeria spp., such as Listeria innocua (26 isolates), Listeria grayi (9), Listeria welshimeri (3), Listeria seeligeri (3), and Listeria ivanovii (2), were also detected. L. monocytogenes was isolated from 5.4% of the 182 samples of pâté. Only 1 of the 10 positive samples harbored >100 L. monocytogenes CFU/g. Two other species of Listeria were observed in pâté: L. innocua (12 isolates) and L. grayi (2).
Topics: Animals; Colony Count, Microbial; Fishes; Food Contamination; Food Microbiology; Listeria; Listeria monocytogenes; Prevalence; Smoke; Spain
PubMed: 11770642
DOI: 10.4315/0362-028x-64.12.2075 -
Veterinary Medicine International 2022A cross-sectional study was conducted to estimate the prevalence and associated risk factors of species and assess the antibiogram of () isolated from milk and milk...
A cross-sectional study was conducted to estimate the prevalence and associated risk factors of species and assess the antibiogram of () isolated from milk and milk products from Holeta, Ambo, and Bako towns, Ethiopia. A total of 482 samples (384 milk, 35 cottage cheeses, 30 bulk tank milk, and 33 curdle milk) were collected using a systematic random sampling method and isolation and identification of species were done using standard microbiological techniques. An antimicrobial susceptibility test for was performed using the Kirby-Bauer disk diffusion technique. Descriptive statistics were used to summarize the prevalence of while the Chi-square test and logistic regression were used to determine the association between the prevalence of and the risk factors and the magnitude of association, respectively. The overall isolation rate of species from milk and milk products was 7.67% (37/482; 95% confidence interval (CI): 5.46, 10.42). The highest prevalence of species (15.15%; 95% CI: 5.11-31.90) was detected in bulk tank milk and the lowest prevalence of species (6.67%; 95% CI: 0.82-22.07) and (0.00; 95% CI: 0.00-1.15) was found in curdled milk. The other species isolated were 0.62% (3/482; 95% CI: 0.13-1.81), 1.04% (5/482; 95% CI: 0.33-2.40), 1.24%, (6/482; 95% CI: 0.45-2.68), and 2.49% (12/482; 95% CI: 5.46-10.42). Univariable logistic regression showed that study town, herd size, farm size, number of lactating cows, and management system were the factors significantly associated with the isolation of species at farm level, while the intensive management system was the independent predictor at cow level in the multivariable model (adjusted odds ratio = 3.38, =0.046). isolates showed the highest resistance against oxacillin (100%), amoxicillin (90.91%), and vancomycine (81.82%). showed a very high multidrug resistance (MDR) [81.82%]. In conclusion, the current study showed the widespread type of species MDR isolates in cow raw milk and milk products from Ambo, Holeta, and Bako towns, Oromia Regional State, Ethiopia.
PubMed: 35465403
DOI: 10.1155/2022/5643478 -
Nature Microbiology Mar 2023Type VI CRISPR systems protect against phage infection using the RNA-guided nuclease Cas13 to recognize viral messenger RNA. Upon target recognition, Cas13 cleaves phage...
Type VI CRISPR systems protect against phage infection using the RNA-guided nuclease Cas13 to recognize viral messenger RNA. Upon target recognition, Cas13 cleaves phage and host transcripts non-specifically, leading to cell dormancy that is incompatible with phage propagation. However, whether and how infected cells recover from dormancy is unclear. Here we show that type VI CRISPR and DNA-cleaving restriction-modification (RM) systems frequently co-occur and synergize to clear phage infections and resuscitate cells. In the natural type VI CRISPR host Listeria seeligeri, we show that RM cleaves the phage genome, thus removing the source of phage transcripts and enabling cells to recover from Cas13-induced cellular dormancy. We find that phage infections are neutralized more effectively when Cas13 and RM systems operate together. Our work reveals that type VI CRISPR immunity is cell-autonomous and non-abortive when paired with RM, and hints at other synergistic roles for the diverse host-directed immune systems in bacteria.
Topics: Bacteriophages; DNA Restriction Enzymes; CRISPR-Cas Systems; Bacteria; DNA Restriction-Modification Enzymes; RNA, Viral; DNA
PubMed: 36782027
DOI: 10.1038/s41564-022-01318-2 -
Applied and Environmental Microbiology Feb 2023Listeria monocytogenes causes the severe foodborne disease listeriosis. Several clonal groups of L. monocytogenes possess the pathogenicity islands pathogenicity island...
Listeria monocytogenes causes the severe foodborne disease listeriosis. Several clonal groups of L. monocytogenes possess the pathogenicity islands pathogenicity island 3 (LIPI-3) and LIPI-4. Here, we investigated the prevalence and genetic diversity of LIPI-3 and LIPI-4 among 63 strains of seven nonpathogenic spp. from the natural environment, i.e., wildlife (black bears []) and surface water. Analysis of the whole-genome sequence data suggested that both islands were horizontally acquired but differed considerably in their incidence and genetic diversity. LIPI-3 was identified among half of the strains in the same genomic location as in L. monocytogenes ( hot spot) in a truncated form, with only three strains harboring full-length LIPI-3, and a highly divergent partial LIPI-3 was observed in three Listeria seeligeri strains, outside the hot spot. Premature stop codons (PMSCs) and frameshifts were frequently noted in the LIPI-3 gene encoding listeriolysin S. On the other hand, full-length LIPI-4 without any PMSCs was found in all Listeria innocua strains, in the same genomic location as L. monocytogenes and with ~85% similarity to the L. monocytogenes counterpart. Our study provides intriguing examples of genetic changes that pathogenicity islands may undergo in nonpathogenic bacterial species, potentially in response to environmental pressures that promote either maintenance or degeneration of the islands. Investigations of the roles that LIPI-3 and LIPI-4 play in nonpathogenic spp. are warranted to further understand the differential evolution of genetic elements in pathogenic versus nonpathogenic hosts of the same genus. Listeria monocytogenes is a serious foodborne pathogen that can harbor the pathogenicity islands pathogenicity island 3 (LIPI-3) and LIPI-4. Intriguingly, these have also been reported in nonpathogenic from food and farm environments, though limited information is available for strains from the natural environment. Here, we analyzed whole-genome sequence data of nonpathogenic spp. from wildlife and surface water to further elucidate the genetic diversity and evolution of LIPI-3 and LIPI-4 in . While the full-length islands were found only in , LIPI-3 was uncommon and exhibited frequent truncation and genetic diversification, while LIPI-4 was remarkable in being ubiquitous, albeit diversified from L. monocytogenes. These contrasting features demonstrate that pathogenicity islands in nonpathogenic hosts can evolve along different trajectories, leading to either degeneration or maintenance, and highlight the need to examine their physiological roles in nonpathogenic hosts.
Topics: Humans; Genomic Islands; Listeria; Listeriosis; Listeria monocytogenes; Genetic Variation; Food Microbiology
PubMed: 36728444
DOI: 10.1128/aem.02097-22 -
Infection and Drug Resistance 2021Listeriosis is one of the globally distributed foodborne diseases with the highest fatality rate. The objectives of this study were to isolate and identify species,...
PURPOSE
Listeriosis is one of the globally distributed foodborne diseases with the highest fatality rate. The objectives of this study were to isolate and identify species, assess factors for contamination of beef, and antibiogram of in Ambo and Holeta towns, Central Ethiopia.
MATERIALS AND METHODS
A total of 450 meat samples were collected from abattoirs (n=150), butchers (n=150), and restaurants (n=150) for isolation and identification of species. Logistic regression analysis was used to assess the association between the occurrence of species in meat and potential risk factors. The antimicrobial susceptibility test was done using the Kirby Bauer test.
RESULTS
The overall occurrence of species in Ambo and Holeta towns was 28.4% (128/450; 95% confidence interval [CI]: 24.3-32.9%). The isolation rate of was 4.4%, 2.2%, 1.8%, 3.8%, 6.2%, and 10.2%. The probability of contamination of meat in butchers and restaurants was higher in Holeta than Ambo [OR=3.4; 95%; p=0.001], in dry than wet season [OR=5.2; p=0.009], and where the hygiene of cutting boards was poor (OR=7.7; p=0.008). Of the 20 isolates, 80%, 70%, 60%, and 55% were resistant to oxacillin, amikacin, and nalidixic acid, chloramphenicol, and tetracycline, respectively. The isolates were 95%, 90%, and 85% susceptible to amoxicillin, vancomycin, and clindamycin, respectively. About 95% of isolates were multidrug-resistant. One isolate (5%) had developed resistance to 10 classes of antimicrobial drugs.
CONCLUSION
species are widespread and study towns, season, and hygiene of cutting boards are independent predictors of isolation of species. Multidrug resistance among was very high. Therefore, adequate cooking of meat, regular training of beef handlers, prudent use of drugs, and further molecular studies on species are important.
PubMed: 33907427
DOI: 10.2147/IDR.S304871 -
Applied and Environmental Microbiology Aug 2010While Listeria seeligeri and L. monocytogenes contain the main Listeria virulence gene cluster, only L. monocytogenes is considered an intracellular pathogen. Initial...
Complementation of Listeria monocytogenes null mutants with selected Listeria seeligeri virulence genes suggests functional adaptation of Hly and PrfA and considerable diversification of prfA regulation in L. seeligeri.
While Listeria seeligeri and L. monocytogenes contain the main Listeria virulence gene cluster, only L. monocytogenes is considered an intracellular pathogen. Initial evolutionary analyses showed that the virulence genes prfA, hly, and plcA are conserved in L. seeligeri, with specific Hly and PrfA amino acid residues showing evidence for positive selection in L. seeligeri. Our data also show that temperature-dependent transcript patterns for prfA, which encodes a transcriptional regulator of virulence genes, differed between L. monocytogenes and L. seeligeri. To further investigate the divergence of virulence gene function and regulation, L. seeligeri prfA (prfA(LS)), hly (hly(LS)), and plcA (plcA(LS)), as well as prfA(LS) constructs with different prfA promoter regions, were introduced into appropriate L. monocytogenes null mutants. Only when prfA(LS) was under the control of the L. monocytogenes prfA promoters (P1- and P2prfA) (P1P2(LM) prfA(LS)) was prfA(LS) able to fully complement the Delta prfA(LM) deletion. hly(LS) introduced into an L. monocytogenes background under its native promoter showed transcript levels similar to those of hly(LM) and was able to partially restore L. monocytogenes wild-type-level hemolysis and intracellular growth, even though Hly(LM) and Hly(LS) showed distinct patterns of cell- and supernatant-associated hemolytic activities. Our data indicate that (i) regulation of prfA expression differs between L. monocytogenes and L. seeligeri, although hly transcription is temperature dependent in both species, and (ii) PrfA and Hly functions are largely, but not fully, conserved between L. seeligeri and L. monocytogenes. Virulence gene homologues and their expression thus appear to have adapted to distinct but possibly related functions in these two species.
Topics: Bacterial Proteins; DNA, Bacterial; Gene Expression Regulation, Bacterial; Genetic Complementation Test; Hemolysin Proteins; Hemolysis; Listeria; Molecular Sequence Data; Sequence Analysis, DNA; Transcription Factors; Virulence; Virulence Factors
PubMed: 20543041
DOI: 10.1128/AEM.03107-09 -
Journal of Food Protection Mar 2022Reference methods developed for detection of Listeria monocytogenes are commonly used for detection of Listeria at the genus level. Improved method performance data are...
Assessment of Reference Method Selective Broth and Plating Media with 19 Listeria Species Highlights the Importance of Including Diverse Species in Listeria Method Evaluations.
ABSTRACT
Reference methods developed for detection of Listeria monocytogenes are commonly used for detection of Listeria at the genus level. Improved method performance data are needed because this genus has expanded from 6 to 26 species and now includes several Listeria sensu lato species, which can have phenotypes distinct from those of Listeria sensu stricto. We evaluated growth of 19 Listeria species, including 12 recently described Listeria sensu lato species, using the media specified by (i) the U.S. Food and Drug Administration (FDA) Bacteriological Analytical Manual, (ii) the U.S. Department of Agriculture (USDA) Microbiology Laboratory Guidebook, and (iii) the International Organization for Standardization (ISO). The FDA broth enrichment procedure allowed all species to grow to detectable levels (≥4 log CFU/mL), yielded the highest mean growth (7.58 log CFU/mL), and was the only procedure with which no Listeria sensu lato species yielded significantly higher growth than did a comparison Listeria sensu stricto species. With the USDA and ISO broth enrichment procedures, several Listeria sensu lato species yielded significantly higher growth than did either Listeria seeligeri or Listeria ivanovii, suggesting that these two Listeria sensu stricto species could be outgrown by Listeria sensu lato species. On selective and differential agar media, L. seeligeri, L. ivanovii, and Listeria grayi produced colonies with atypical morphology and/or growth of these species was inhibited (which may lead to incorrect classification of a sample as negative), whereas several newly described Listeria sensu lato species grew to high levels and produced colonies with typical morphology. Overall, our study results indicate that the ability to detect various Listeria species can be impacted by the specific broth and selective and differential agar used. Our data can help guide selection of appropriate media and detection methods for environmental Listeria monitoring programs and methods that are most likely to detect the targeted Listeria groups (e.g., Listeria sensu stricto, which appear to be the most appropriate index organisms for the pathogen L. monocytogenes).
Topics: Culture Media; Food Microbiology; Listeria; Listeria monocytogenes
PubMed: 34855940
DOI: 10.4315/JFP-21-293 -
Journal of Food Protection Nov 2014Postprocessing contamination in processing plants has historically been a significant source of Listeria monocytogenes in ready-to-eat delicatessen meats, and therefore...
Postprocessing contamination in processing plants has historically been a significant source of Listeria monocytogenes in ready-to-eat delicatessen meats, and therefore a major cause of human listeriosis cases and outbreaks. Recent risk assessments suggest that a majority of human listeriosis cases linked to consumption of contaminated deli meats may be due to L. monocytogenes contamination that occurs at the retail level. To better understand the ecology and transmission of Listeria spp. in retail delicatessens, food and nonfood contact surfaces were tested for L. monocytogenes and other Listeria spp. in a longitudinal study conducted in 30 retail delis in three U.S. states. In phase I of the study, seven sponge samples were collected monthly for 3 months in 15 delis (5 delis per state) prior to start of daily operation; in phase II, 28 food contact and nonfood contact sites were sampled in each of 30 delis during daily operation for 6 months. Among the 314 samples collected during phase I, 6.8% were positive for L. monocytogenes. Among 4,503 samples collected during phase II, 9.5% were positive for L. monocytogenes; 9 of 30 delis showed low L. monocytogenes prevalence (<1%) for all surfaces. A total of 245 Listeria spp. isolates, including 184 Listeria innocua, 48 Listeria seeligeri, and 13 Listeria welshimeri were characterized. Pulsed-field gel electrophoresis (PFGE) was used to characterize 446 L. monocytogenes isolates. PFGE showed that for 12 of 30 delis, one or more PFGE types were isolated on at least three separate occasions, providing evidence for persistence of a given L. monocytogenes subtype in the delis. For some delis, PFGE patterns for isolates from nonfood contact surfaces were distinct from patterns for occasional food contact surface isolates, suggesting limited cross-contamination between these sites in some delis. This study provides longitudinal data on L. monocytogenes contamination patterns in retail delis, which should facilitate further development of control strategies in retail delis.
Topics: Electrophoresis, Gel, Pulsed-Field; Equipment Contamination; Food Contamination; Food Handling; Humans; Listeria; Listeria monocytogenes; Listeriosis; Longitudinal Studies; Meat Products; Prevalence; United States
PubMed: 25364927
DOI: 10.4315/0362-028X.JFP-14-183