ORCID Profile
0000-0001-5921-3455
Current Organisations
University of Michigan
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Northumbria University
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Publisher: Elsevier BV
Date: 12-2017
Publisher: Frontiers Media SA
Date: 2013
Publisher: Frontiers Media SA
Date: 2014
Publisher: BMJ
Date: 09-2013
Publisher: Elsevier BV
Date: 09-2018
Publisher: American Society for Microbiology
Date: 27-10-2016
Abstract: We report here the draft genome of Enterobacter ludwigii NCR3, a Gram-negative bacterium isolated from the Carpobrotus rossii (Haw.) Schwantes rhizosphere. The analysis of the ~4.8-Mb draft genome shows that this strain harbors several genes associated with heavy metal resistance and plant growth–promoting activity, suggesting its potential application in microbe-assisted phytoremediation.
Publisher: American Society for Microbiology
Date: 28-08-2019
Abstract: This study extends current understanding of the genetic ersity among L. monocytogenes from various food products and food processing environments. Application of WGS-based strategies facilitated tracking of this pathogen of importance to human health along the production chain while providing insights into the pathogenic potential for some of the L. monocytogenes isolates recovered. These analyses enabled the grouping of selected isolates into three putative virulence categories according to their genotypes along with informing selection for phenotypic assessment of their pathogenicity using the zebrafish embryo infection model. It has also facilitated the identification of those isolates with genes conferring tolerance to commercially used biocides. Findings from this study highlight the potential for the application of WGS as a proactive tool to support food safety controls as applied to L. monocytogenes .
Publisher: MDPI AG
Date: 09-02-2018
DOI: 10.3390/GENES9020080
Abstract: The current global crisis of antimicrobial resistance (AMR) among important human bacterial pathogens has been lified by an increased resistance prevalence. In recent years, a number of studies have reported higher resistance levels among Listeria monocytogenes isolates, which may have implications for treatment of listeriosis infection where resistance to key treatment antimicrobials is noted. This study examined the genotypic and phenotypic AMR patterns of 100 L. monocytogenes isolates originating from food production supplies in Australia and examined this in the context of global population trends. Low levels of resistance were noted to ciprofloxacin (2%) and erythromycin (1%) however, no resistance was observed to penicillin G or tetracycline. Resistance to ciprofloxacin was associated with a mutation in the fepR gene in one isolate however, no genetic basis for resistance in the other isolate was identified. Resistance to erythromycin was correlated with the presence of the ermB resistance gene. Both resistant isolates belonged to clonal complex 1 (CC1), and analysis of these in the context of global CC1 isolates suggested that they were more similar to isolates from India rather than the other CC1 isolates included in this study. This study provides baseline AMR data for L. monocytogenes isolated in Australia, identifies key genetic markers underlying this resistance, and highlights the need for global molecular surveillance of resistance patterns to maintain control over the potential dissemination of AMR isolates.
Publisher: Springer Science and Business Media LLC
Date: 15-03-2007
DOI: 10.1007/S10482-007-9155-5
Abstract: Helicobacter hepaticus infects the bowel and biliary tree of several animals, producing inflammation. Colonisation of mouse livers can induce hepatocellular carcinomas. The effects of H. hepaticus on the proliferation and global protein expression of human HEp-2 cells were studied by examining the changes in the protein profiles of cells exposed to the bacterium. HEp-2 cells were grown for four days under a microaerobic atmosphere or under the same conditions in co-cultures with H. hepaticus at various inoculum densities. Enlargement, distension and elongation of HEp-2 cells were observed in co-cultures with H. hepaticus. The number of live cells declined by only an order of magnitude at bacterial inocula of approximately 10(9)cfu/ml, but were reduced to less than 10(3)cells/ml at approximately 10(10)cfu/ml bacteria inocula. Protein expression by HEp-2 cells was investigated employing two-dimensional gel electrophoresis. In cells grown with or without bacteria, 17 differentially expressed proteins were identified by tandem mass spectrometry. These proteins participated in several biological functions including amino acid metabolism, cell growth and proliferation, stress response, protein translation and modification, etc. The onset of a catastrophic killing of HEp-2 cells at a bacterial density of approximately 10(9)cfu/ml suggested a multimodal action for H. hepaticus infection, and the modulation of the expression of proteins involved in different biological functions showed that the presence of H. hepaticus has broad effects on the physiology of HEp-2 cells.
Publisher: Elsevier BV
Date: 08-2014
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-2007
DOI: 10.1161/STROKEAHA.106.477448
Abstract: Background and Purpose— Abnormalities in neurocognitive function are common after surgery for aneurysmal subarachnoid hemorrhage, even among patients with good functional outcomes. The time course of neurocognitive recovery, along with the long-term effects of mild intraoperative hypothermia (33°C) and aneurysm location, is unknown. We determined these in a subset of subarachnoid hemorrhage patients enrolled in the Intraoperative Hypothermia for Aneurysm Surgery Trial (IHAST). Methods— We performed a longitudinal, multicenter, prospective, blinded study of adult IHAST patients with a Glasgow Outcome Score=1 or 2 (independent function), 3 months postsurgery and a matched control group (n=45). Subjects were tested with a 5-test cognitive function battery and standard neurological evaluations at 3, 9 and 15 months postsurgery. The primary outcome measure was a composite score on cognitive test performance. Results— There were 303 IHAST patients available for inclusion: 218 eligible, 185 enrolled (89 hypothermic, 96 normothermic). Significant cognitive improvement was noted from 3 to 9 ( P .001) and 3 to 15 ( P .001) months in both hypothermic and normothermic groups, even after adjusting for practice effects observed in the control group. No significant change was identified between 9 and 15 months. Neither mild hypothermia nor aneurysm location (anterior communicating artery versus others) had a significant effect on recovery over time or frequency of cognitive impairment. Compared with control group, the frequency of cognitive impairment ( Z score −1.96) in all patients at 3, 9 and 15 months was 36%, 26% and 23%, respectively. Conclusions— In this population, cognitive improvement continued beyond 3 months, with a plateau between 9 and 15 months. This was not affected by the use of intraoperative hypothermia or anatomical location of aneurysm.
Publisher: American Society for Microbiology
Date: 27-10-2016
Abstract: Rhodococcus erythropolis NSX2 is a rhizobacterium isolated from a heavy metal–contaminated environment. The 6.2-Mb annotated genome sequence shows that this strain harbors genes associated with heavy-metal resistance and xenobiotics degradation.
Publisher: Elsevier BV
Date: 11-2007
Publisher: Oxford University Press (OUP)
Date: 11-2021
DOI: 10.1111/JAM.15089
Abstract: Listeria species may colonize and persist in food processing facilities for prolonged periods of time, despite hygiene interventions in place. To understand the genetic factors contributing to persistence of Listeria strains, this study undertook a comparative analysis of seven persistent and six presumed non-persistent strains, isolated from a single food processing environment, to identify genetic markers correlating to promoting persistence of Listeria strains, through whole genome sequence analysis. A erse pool of genetic markers relevant to hygiene tolerance was identified, including disinfectant resistance markers qacH, emrC and the efflux cassette bcrABC. Both persistent and presumed non-persistent cohorts encoded a range of stress resistance markers, including heavy metal resistance, oxidative and pH stress, although trends were associated with each cohort (e.g., qacH and cadA1C resistance was more frequently found in persistent isolates). Persistent isolates were more likely to contain mutations associated with attenuated virulence, including a truncated InlA. Plasmids and transposons were widespread between cohorts. Results suggest that no single genetic marker identified was universally responsible for a strain's ability to persist. Persistent strains were more likely to harbour mutation associated with hypovirulence. This study provides additional insights into the distribution of genetic elements relevant to persistence across Listeria species, as well as strain virulence potential.
Publisher: Springer Science and Business Media LLC
Date: 10-12-2018
Publisher: Wiley
Date: 30-11-2011
DOI: 10.1111/J.1863-2378.2011.01443.X
Abstract: Verocytotoxigenic Escherichia coli (VTEC) are highly significant zoonotic threats to public health, and have been the causative agent implicated in numerous high-profile outbreaks affecting large numbers of people. Serovar O157 is most frequently linked with human illness however, other serovars, such as O26, O103, O111 and O145, have also been implicated. This study aimed to characterize the prevalence and virulence determinants of these five serovars in Irish dairy farm herds, and their milk. Using real-time PCR (RTi-PCR), bovine rectal faecal swabs and raw milk s les, along with milk filters, were screened for the presence of vt genes. Positive s les were then screened for the five serovars using sero-specific PCR. Serovar-positive s les were subjected to immunomagnetic separation, to isolate viable VTEC strains. These isolates were subsequently screened for four virulence factors: vt1, vt2, eaeA and hlyA. Three hundred and eighty six of the 600 rectal faecal swabs, 85 of the 117 milk-filters and 43 of the 120 bulk-tank milk s les, were positive for vt genes. From these 514 total vt-positive s les, 58 O26, 162 O103, 1 O111, 324 O145 and 26 O157 positives were detected by sero-specific RTi-PCR. Immunomagnetic separation yielded 12 O26, 26 O103, 0 O111, 19 O145 and 10 O157 isolates. Ten of these isolates contained at least one of the four virulence determinants screened for (i.e. vt1, vt2, eaeA and hlyA). Of these 10 isolates, pulsed-field gel electrophoresis showed that two of the O26 isolates from different farms were indistinguishable. Two O157 isolates were also indistinguishable. This study found serovars O103 and O145 to be the most prevalent in s les tested. Apart from the occurrence of VTEC in dairy herds, this study shows a high occurrence of vt genes in the environment, creating the possibility of horizontal gene transfer and emergence of new VTEC strains.
Publisher: Springer Science and Business Media LLC
Date: 19-02-2015
Publisher: American Society for Microbiology
Date: 06-2014
DOI: 10.1128/AEM.00468-14
Abstract: Listeria species experience complex interactions with other microorganisms, which may promote growth and colonization of the organism in local environments or negatively affect them. This study investigated the microbial community at a food production facility, examining interactions between Listeria and the associated microbiome. Listeria species can be transferred between zones in the production environment by in iduals or equipment, and drains may act as a reservoir for the organism, reflecting the microbial flora potentially in the production environment. Drains that were colonized by Listeria species and those determined to be free of Listeria were examined. In each case, 16S rRNA gene analysis was performed using the PhyloChip platform. Some general similarities in bacterial population structure were observed when Listeria -negative and -positive drain communities were compared, with some distinct differences also noted. These included increased populations of the genera Prevotella and Janthinobacterium associated with the absence of Listeria species, whereas Enterococcus and Rhodococcus were in higher abundance in drains colonized by Listeria species. Based on these results, a selection of bacterial species were grown in coculture biofilm with a Listeria monocytogenes strain identified as having colonized a drain at the facility. Mixed-species biofilm experiments showed that Janthinobacterium inhibited attachment and subsequent biofilm formation of L. monocytogenes however, Enterococcus gallinarum significantly increased it. The results of this study suggest the microbial community in food processing facilities can impact the colonization of Listeria species and that influencing the microbiome in favor of antilisterial species may reduce the colonization of Listeria species and limit the likelihood of product rocess contamination.
Publisher: Wiley
Date: 02-2008
Publisher: Frontiers Media SA
Date: 16-07-2019
Publisher: American Dairy Science Association
Date: 09-2019
Abstract: Bacillus cereus sensu lato is one of the most harmful bacterial groups affecting the quality and safety of powdered infant formula (PIF). In this study, s les were collected from the raw materials and processing environments of PIF. A total of 84 isolates were identified as Bacillus cereus sensu stricto (B. cereus s. s.) by 16S rRNA analysis, molecular typing technology, and physiological and biochemical tests. The 84 B. cereus s. s. strains were assigned to panC group II, group III, and group IV. Then, the 7 housekeeping genes glpF, gmk, ilvD, pta, pur, pycA, and tpi were selected for multilocus sequence typing. Results showed that the 84 isolates were clustered into 24 sequence types (ST), and 14 novel ST were detected. Among the 24 ST, ST999 (19/84, 22.62%) and ST1343 (13/84, 15.48%) predominated. The correlation between processing areas and ST showed that the processing environments of the production and packing areas were the most susceptible to contamination by B. cereus s. s. Spores of these ST showed different heat resistance phenotypes evaluated by the analysis of D
Publisher: American Society for Microbiology
Date: 08-06-2017
Abstract: We report here the draft genome sequence of Leifsonia sp. strain NCR5, a Gram-positive actinomycete isolated from Carpobrotus rossii (Haw.) Schwantes rhizosphere. The de novo genome of Leifsonia sp. strain NCR5 was assembled with 69 scaffolds and a G+C content of 69%, was 4.2 Mb in length, and contained 3,952 coding sequences.
Publisher: Wiley
Date: 21-04-2023
Abstract: Antimicrobial agents are a critical component of modern healthcare systems, fulfilling a core function in patient care and improving in idual patient outcomes and consequently overall public health. However, the efficacy of antimicrobial interventions is being consistently eroded by the emergence and dissemination of various antimicrobial resistance (AMR) mechanisms. One highly valued class of antimicrobial compounds is carbapenems, which retain efficacy in treating most multidrug‐resistant infections and are considered “last line” agents. Therefore, recent trends in proliferation of carbapenem resistance (CR) via dissemination of carbapenemase‐encoding genes among members of the Enterobacteriaceae family pose a significant threat to public health. While much of the focus relating to this has been on nosocomial environments, community‐acquired carbapenemase‐producing Enterobacteriaceae (CPE) infections and their associated transmission routes are less well studied. Among these community‐associated vectors, the role of food chains and contaminated foods is important, since Enterobacteriaceae occupy niches within these settings. This review examines foodborne CPE transmission by exploring how interactions within and between food, the food chain, and agriculture not only promote and disseminate CPE, but also create reservoirs of mobile genetic elements that may lead to further carbapenemase gene proliferation both within and between microbial communities. Additionally, recent developments regarding the global occurrence and molecular epidemiology of CPEs in food chains will be reviewed.
Publisher: Springer New York
Date: 2014
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.4315/0362-028X-72.7.1450
Abstract: Listeria monocytogenes is a potentially lethal foodborne pathogen commonly found in the environment. European Union hygiene legislation places responsibility for safety on primary production facilities, including farms, as part of a policy to introduce traceability throughout the food chain. This study aimed to determine the occurrence of L. monocytogenes in the Irish dairy farm environment and in particular the milking facility. Two hundred ninety-eight environmental s les were collected from 16 farms in the southern region of Ireland. A number of farms within the group supply raw milk to the unpasteurized milk cheese industry. The s les taken included cow feces, milk, silage, soil, water, etc. S les were enriched in Listeria enrichment broth and incubated for 48 h, followed by plating on chromogenic agar Listeria Ottavani & Agosti and further incubation of the plates for 24 to 48 h. Presumptive L. monocytogenes isolates were purified and confirmed by PCR targeting the hly gene. Overall, 19% of the s les (57 of 298) were positive for L. monocytogenes. These were serotyped using conventional and PCR methods serotypes 1/2a, 1/2b, and 4b made up 78% of the typeable isolates. A correlation was found between the level of hygiene standards on the farm and the occurrence of L. monocytogenes. There was little difference in the occurrence of L. monocytogenes between farms supplying milk to the unpasteurized milk cheese industry and those supplying milk for processing. This study demonstrates the prevalence of L. monocytogenes in the dairy farm environment and the need for good hygiene practices to prevent its entry into the food chain.
Publisher: American Society for Microbiology
Date: 02-05-2013
Abstract: Cronobacter is an opportunistic pathogen associated with meningitis in neonates. Based on long-term surveillance of a powdered infant formula production facility, a persistent and thermotolerant isolate, denoted Cronobacter sakazakii SP291, was detected. Here we report the complete genome along with the sequences of three plasmids identified in this organism.
Publisher: Elsevier BV
Date: 10-2015
Abstract: Surveillance and control of food-borne human pathogens, such as Listeria monocytogenes, is a critical aspect of modern food safety programs at food production facilities. This study evaluated contamination patterns of Listeria species at a poultry food production facility, and evaluated the efficacy of procedures to control the contamination and transfer of the bacteria throughout the plant. The presence of Listeria species was studied along the production chain, including raw ingredients, food-contact, non-food-contact surfaces, and finished product. All isolates were sub-typed by pulsed-field gel electrophoresis (PFGE) to identify possible entry points for Listeria species into the production chain, as well as identifying possible transfer routes through the facility. The efficacy of selected in-house sanitizers against a sub-set of the isolates was evaluated. Of the 77 different PFGE-types identified, 10 were found among two or more of the five categories/areas (ingredients, food preparation, cooking and packing, bulk packing, and product), indicating potential transfer routes at the facility. One of the six sanitizers used was identified as unsuitable for control of Listeria species. Combining PFGE data, together with information on isolate location and timeframe, facilitated identification of a persistent Listeria species contamination that had colonized the facility, along with others that were transient.
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/MA17022
Publisher: American Society for Microbiology
Date: 27-10-2016
Abstract: Bacillus cereus LCR12 is a plant growth–promoting rhizobacterium, isolated from a heavy metal–contaminated environment. The 6.01-Mb annotated genome sequence provides the genetic basis for revealing its potential application to remediate contaminated soils in association with plants.
Publisher: Frontiers Media SA
Date: 05-06-2018
Publisher: Oxford University Press (OUP)
Date: 10-2008
DOI: 10.1111/J.1365-2672.2008.03836.X
Abstract: The current international standard method for detection of Enterobacter sakazakii from milk products is by the International Organization for Standardization and the International Dairy Federation documented method, a procedure involving two-step enrichment. This study aimed to assess enrichment of E. sakazakii using a one-step enrichment. Enrichment of four strains of E. sakazakii was compared using five different media, with stressed or unstressed cells, and at three levels of competing microflora, which were included to assess their effects on the positive isolation of E. sakazakii. Enrichment of milk powders, prepared by spray-drying milk seeded with E. sakazakii, was assessed using one-step enrichment for detection of E. sakazakii, followed by confirmation of positive isolates by real-time PCR. Current media are unsuitable for enrichment and detection of all E. sakazakii isolates, in particular, when high levels of background microflora are present in the s le matrix, and new defined media are needed for successful one-step enrichment. These findings provide further analysis of one-step enrichment processes for E. sakazakii in the presence of competing microflora, and show that further formulation is needed for a universal E. sakazakii enrichment medium, with careful selection of both nutrients and selective agents.
Publisher: Microbiology Society
Date: 04-2012
Abstract: Listeria monocytogenes is an important foodborne human pathogen. Human infection is associated with high mortality rates. Epidemiological investigation and molecular subtyping can be useful in linking human illness with specific sources of infection. This retrospective study describes the use of PFGE to examine relationships of 222 isolates from human and non-human sources in Ireland. Human clinical isolates from other countries were also examined. Eight small clusters of human and non-human isolates (mostly serotype 4b) that were indistinguishable from one another were detected, suggesting potential sources for human infection. For non-human isolates, some PFGE types appeared to be exclusively associated with a single source, whereas other PFGE-types appeared to be more widely disseminated. Indistinguishable, or highly related clusters of isolates of Irish and non-Irish origin suggest that some PFGE patterns may be globally distributed.
Publisher: Mary Ann Liebert Inc
Date: 2014
Abstract: Cross-contamination via equipment and the food-processing environment has been implicated as the main cause of Listeria monocytogenes transmission. The aim of this study, therefore, was to determine the occurrence and potential persistence of L. monocytogenes in 19 European cheese-processing facilities. A s ling approach in 2007-2008 included, respectively, 11 and two industrial cheese producers in Austria and the Czech Republic, as well as six Irish on-farm cheese producers. From some of the producers, isolates were available from s ling before 2007. All isolates from both periods were included in a strain collection consisting of 226 L. monocytogenes isolates, which were then typed by serotyping and pulsed-field gel electrophoresis (PFGE). In addition, metabolic fingerprints from a subset of isolates were obtained by means of Fourier-transform infrared (FTIR) spectroscopy. PFGE typing showed that six processing environments were colonized with seven persistent PFGE types of L. monocytogenes. Multilocus sequence typing undertaken on representatives of the seven persisting PFGE types grouped them into distinct clades on the basis of country and origin however, two persistent strains from an Austrian and an Irish food processor were shown to be clonal. It was concluded that despite the fact that elaborate Hazard Analysis and Critical Control Point concepts and cleaning programs are applied, persistent occurrence of L. monocytogenes can take place during cheese making. L. monocytogenes sanitation programs could be strengthened by including rapid analytical tools, such as FTIR, which allow prescreening of potentially persistent L. monocytogenes contaminants.
Publisher: Oxford University Press (OUP)
Date: 03-05-2012
DOI: 10.1093/HMG/DDS161
Publisher: Elsevier BV
Date: 12-2006
Publisher: American Society for Microbiology
Date: 30-06-2016
Abstract: Listeria monocytogenes is a foodborne pathogen and the causative agent of listeriosis among humans and animals. The draft genome sequences of L. monocytogenes serotype 4b strains 944 and 2993 and serotype 1/2c strains 198 and 2932 are reported here.
Publisher: Springer New York
Date: 2014
DOI: 10.1007/978-1-4939-0703-8_9
Abstract: High-throughput biochemical screening techniques are an important tool in phenotypic analysis of bacteria. New methods, simultaneously measuring many phenotype responses, increase the output of such investigations and allow a more complete overview of the bacterial phenotype, and how this may relate its genotype. This chapter describes the application of OmniLog Phenotype Microarray analysis, a high-throughput assay for the phenotypic characterization of bacterial strains across a variety of different traits, including nutrient utilization and antimicrobial sensitivity, to Listeria species.
Publisher: Oxford University Press (OUP)
Date: 02-2007
Publisher: Frontiers Media SA
Date: 06-04-2017
Publisher: Frontiers Media SA
Date: 23-08-2017
Publisher: Frontiers Media SA
Date: 22-12-2016
Publisher: Elsevier BV
Date: 03-2011
DOI: 10.1016/J.IJFOODMICRO.2010.10.012
Abstract: Sixteen cheesemaking facilities were s led during the production season at monthly intervals over a two-year period. Thirteen facilities were found to have s les positive for Listeria monocytogenes. S les were ided into 4 categories cheese, raw milk, processing environment and external to the processing environment (s les from the farm such as silage, bedding, and pooled water). In order to attempt to identify the source, persistence and putative transfer routes of contamination with the L. monocytogenes isolates, they were differentiated using PFGE and serotyping. Of the 250 isolates, there were 52 different pulsotypes. No pulsotype was found at more than one facility. Two facilities had persistent pulsotypes that were isolated on s ling occasions at least 6 months apart. Of the s les tested, 6.3% of milk, 13.1% of processing environment and 12.3% of s les external to the processing environment, respectively, were positive for L. monocytogenes. Pulsotypes found in raw milk were also found in the processing environment, however, one of the pulsotypes from raw milk was found in cheese on only one occasion. One of the pulsotypes isolated from the environment external to the processing facility was found on the surface of cheese, however, a number of them were found in the processing environment. The results suggest that the farm environment external to the processing environment may in some cases be the source of processing environment contamination with L. monocytogenes.
Publisher: Springer Science and Business Media LLC
Date: 03-04-2011
DOI: 10.1038/NG.801
Publisher: Springer New York
Date: 2015
DOI: 10.1007/978-1-4939-2599-5_7
Abstract: Pulsed-Field Gel Electrophoresis (PFGE) subtyping has been used extensively to characterize various bacterial species and to facilitate comparative analysis of geographically erse populations. To this end, standardized protocols for many different genera and species have been developed, particularly through the PulseNet platform. The Bacillus cereus group of bacteria includes a erse species set, which are of particular importance in food safety as both human pathogens and spoilage organisms. The application of techniques to differentiate strains of B. cereus can be utilized to assist in both disease outbreak investigations, and also in strategies to monitor and control the organism in food production environments. This chapter describes a PFGE method, which may be applied to differentiate B. cereus strains.
Publisher: Springer New York
Date: 2015
DOI: 10.1007/978-1-4939-2599-5_5
Abstract: Pulsed-Field Gel Electrophoresis (PFGE) is a molecular subtyping method with high discriminatory power, reproducibility, and epidemiological concordance for the subtyping of Listeria monocytogenes and other bacteria. PFGE uses rare-cutting restriction enzymes (macrorestriction) that cut the genomic DNA, usually resulting in 6-25 DNA fragments ranging between 30 and 600 kb. Bacterial cells are immobilized in agarose plugs and subsequently lysed to release genomic DNA, which is then subjected to DNA digestion. AscI and ApaI restriction enzymes are typically used for L. monocytogenes. Electrophoresis using an alternating electric field direction results in a DNA banding pattern, or fingerprint, which is used to classify isolates into different pulsotypes. PFGE is currently the CDC's gold standard method for epidemiological studies in foodborne outbreaks.
Publisher: American Society for Microbiology
Date: 27-10-2016
Abstract: Listeria monocytogenes sequence type 204 (ST204) strains have been isolated from a range of food, environmental, and clinical sources in Australia. This study describes the draft genome sequences of 15 isolates collected from meat and dairy associated sources.
Publisher: Elsevier BV
Date: 09-2018
Publisher: Frontiers Media SA
Date: 03-04-2018
Publisher: Frontiers Media SA
Date: 21-12-2016
Publisher: Springer Science and Business Media LLC
Date: 08-08-2009
DOI: 10.1007/S10482-009-9370-3
Abstract: The concentration of oxygen in the atmosphere is a common environmental factor which can also be a source of stress for microorganisms. Comparative analyses of the responses of the epsilon-proteobacteria C ylobacter jejuni, Helicobacter pylori and Wolinella succinogenes to elevated oxygen concentrations were carried out using transcriptomics. Microarray data were analysed to determine genes differentially expressed under elevated oxygen concentrations. The results indicated 158, 58 and 82 genes were upregulated and 46, 40 and 65 were downregulated in C. jejuni, H. pylori and W. succinogenes, respectively. The gene encoding the enzyme alkyl hydroperoxide reductase was the only one upregulated at higher oxygen tensions in all three bacterial species. No genes were found to be downregulated in all three species. Functional classification analyses were performed on the genes whose expression was modulated in order to identify common pathways and functional categories which were differentially expressed in the three organisms. Processes upregulated at higher oxygen tensions included translation, oxidative phosphorylation, antioxidation, and nucleic acid metabolism. ABC and ion-coupled transport proteins were generally downregulated at higher oxygen tensions. Finally, insights into the preferred environment were gained from the analyses of the bacterial responses, specifically motility and chemotaxis proteins. W. succinogenes preferred anaerobic conditions as opposed to C. jejuni and H. pylori preference for microaerobic conditions. These comparative studies provide a better understanding of bacterial adaptation to and interaction with their environment.
Publisher: Elsevier BV
Date: 06-2015
DOI: 10.1016/J.IJFOODMICRO.2015.01.023
Abstract: Listeria monocytogenes is an important foodborne pathogen responsible for the sometimes fatal disease listeriosis. Public health concerns and stringent regulations associated with the presence of this pathogen in food and food processing environments underline the need for rapid and reliable detection and subtyping techniques. In the current study, the application of matrix assisted laser desorption/ionisation-time-of-flight mass spectrometry (MALDI-TOF MS) as a single identification and source-tracking tool for a collection of L. monocytogenes isolates, obtained predominantly from dairy sources within Australia, was explored. The isolates were cultured on different growth media and analysed using MALDI-TOF MS at two incubation times (24 and 48 h). Whilst reliable genus-level identification was achieved from most media, identification at the species level was found to be dependent on culture conditions. Successful speciation was highest for isolates cultured on the chromogenic Agar Listeria Ottaviani Agosti agar (ALOA, 91% of isolates) and non-selective horse blood agar (HBA, 89%) for 24h. Chemometric statistical analysis of the MALDI-TOF MS data enabled source-tracking of L. monocytogenes isolates obtained from four different dairy sources. Strain-level discrimination was also observed to be influenced by culture conditions. In addition, t-test/analysis of variance (ANOVA) was used to identify potential biomarker peaks that differentiated the isolates according to their source of isolation. Source-tracking using MALDI-TOF MS was compared and correlated with the gold standard pulsed-field gel electrophoresis (PFGE) technique. The discriminatory index and the congruence between both techniques were compared using the Simpsons Diversity Index and adjusted Rand and Wallace coefficients. Overall, MALDI-TOF MS based source-tracking (using data obtained by culturing the isolates on HBA) and PFGE demonstrated good congruence with a Wallace coefficient of 0.71 and comparable discriminatory indices of 0.89 and 0.86, respectively. MALDI-TOF MS thus represents a rapid and cost-effective source-tracking technique for L. monocytogenes.
Publisher: Elsevier BV
Date: 08-2023
Publisher: American Society for Microbiology
Date: 25-06-2015
Abstract: Listeria monocytogenes is a foodborne pathogen and is the causative agent of listeriosis among humans and animals. The draft genome sequence of L. monocytogenes DPC6895, a serotype 1/2b strain isolated from the raw milk of a cow with subclinical bovine mastitis, is reported.
Publisher: American Society for Microbiology
Date: 12-01-2017
Abstract: This study describes draft whole genomes of 15 Staphylococcus aureus isolates from dairy farms located in Victoria, Australia. Two novel sequence types (ST3183 and ST3184) were identified among these isolates.
Publisher: Springer Science and Business Media LLC
Date: 29-10-2017
DOI: 10.1007/S00253-017-8561-5
Abstract: The ability of bacteria to tolerate acid stress plays an important role in their growth and survival. In particular, aciduric bacteria have several survival systems that prevent cell damage from acid stress. In this study, the effect of the bacterial stress induced by pre-adaptation at different pH values on the cellular macromolecules of Lactobacillus plantarum was investigated using Raman spectroscopy and Fourier transform infrared spectroscopy. The expression of key genes was also quantified to provide understanding of the transcriptional response of the cells to lethal acid stress conditions. Principal component analysis of the spectra exhibited marked differences in the spectral regions associated with carbohydrates, lipids, proteins, and nucleic acids for all acid-stressed cells compared to those of untreated control cells. The changes in spectroscopic and transcriptomic profiles that were observed revealed alterations in bacterial cell wall composition after acid treatment. The results suggest the existence of a complex bacterial stress response in which modifications of cellular compounds from pre-adaption at low pH are involved. This study demonstrates the potential application of vibrational spectroscopy techniques to discriminate between intact and injured bacterial cells as well as to study their stress responses after exposure to acid environments during food processing.
Publisher: Elsevier BV
Date: 08-2015
Publisher: American Society for Microbiology
Date: 15-09-2011
DOI: 10.1128/AEM.05529-11
Abstract: This study aimed to characterize physiological differences between persistent and presumed nonpersistent Listeria monocytogenes strains isolated at processing facilities and to investigate the molecular basis for this by transcriptomic sequencing. Full metabolic profiles of two strains, one persistent and one nonpersistent, were initially screened using Biolog's Phenotype MicroArray (PM) technology. Based on these results, in which major differences from selected antimicrobial agents were detected, another persistent strain and two nonpersistent strains were characterized using two antimicrobial PMs. Resistance to quaternary ammonium compounds (QACs) was shown to be higher among persistent strains. Growth of persistent and nonpersistent strains in various concentrations of the QACs benzethonium chloride (BZT) and cetylpyridinium chloride (CPC) was determined. Transcriptomic sequencing of a persistent and a presumed nonpersistent strain was performed to compare gene expression among these strains in the presence and absence of BZT. Two strains, designated “frequent persisters” because they were the most frequently isolated at the processing facility, showed overall higher resistance to QACs. Transcriptome analysis showed that BZT induced a complex peptidoglycan (PG) biosynthesis response, which may play a key role in BZT resistance. Comparison of persistent and nonpersistent strains indicated that transcription of many genes was upregulated among persistent strains. This included three gene operons: pdu , cob-cbi , and eut . These genes may play a role in the persistence of L. monocytogenes outside the human host.
Publisher: American Dairy Science Association
Date: 05-2020
Publisher: Mary Ann Liebert Inc
Date: 05-2011
Abstract: Many foods originate on the farm where cross-contamination with pathogens can occur, with implications for human health. This study characterized a bank of 51 Listeria monocytogenes isolates originating from 12 farms located in Ireland by pulsed-field gel electrophoresis (PFGE) to establish the molecular ersity of the isolate collection, and examine transmission patterns of L. monocytogenes across the farm environment, and also determined resistances against five different antibiotics ( icillin, ciprofloxacin, erythromycin, penicillin G, and tetracycline). Analysis using a combination of AscI and ApaI digestion showed the 51 isolates comprised a total of 40 in idual PFGE types, compared to in idual restriction enzyme analysis, which was less discriminatory (36 types with ApaI analysis and 38 types with AscI analysis). Four of the PFGE types were common to multiple farms, and five farms had isolates with indistinguishable PFGE types in multiple locations on the farm. Indistinguishable PFGE types were common to multiple farms in different geographical locations up to ~200 km apart, and were found in a variety of different s le types, indicating multiple niches for the organism in the dairy farm environment. The presence of L. monocytogenes in s les related to animals other than cattle indicated that there are multiple possible vectors of contamination. The farm environment harbors a erse collection of L. monocytogenes isolates that must be considered as possible agents of food contamination.
Location: Australia
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Bruno Giordani.