scholarly journals Increased In Vitro Adherence and On-Farm Persistence of Predominant and Persistent Listeria monocytogenes Strains in the Milking System

2011 ◽  
Vol 77 (11) ◽  
pp. 3676-3684 ◽  
Author(s):  
Alejandra A. Latorre ◽  
Jo Ann S. Van Kessel ◽  
Jeffrey S. Karns ◽  
Michael J. Zurakowski ◽  
Abani K. Pradhan ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Restriction Analysis ◽  
Dairy Farm ◽  
Bulk Tank Milk ◽  
Content Type ◽  
Bulk Tank ◽  
High Level ◽  
On Farm ◽  
Adherence Ability

ABSTRACTDairy farms are a reservoir forListeria monocytogenes, and the reduction of this pathogen at the farm level is important for reducing human exposure. The objectives of this research were to study the diversity ofL. monocytogenesstrains on a single dairy farm, assess strain dynamics within the farm, identify potential sources ofL. monocytogenesin bulk tank milk and milk filters, and assess the adherence abilities of representative strains. A total of 248L. monocytogenesisolates were analyzed by pulsed-field gel electrophoresis (PFGE). Combined AscI and ApaI restriction analysis yielded 40 PFGE types (strains). The most predominant strains were T (28.6%), D (22.6%), and F (14.9%). A high level of heterogeneity of strains among isolates from fecal (Simpson's index of diversity [SID] = 0.96) and environmental (SID = 0.96) samples was observed. A higher homogeneity of strains was observed among isolates from milk filters (SID = 0.71) and bulk tank milk (SID = 0.65). Six of 17L. monocytogenesisolates (35.3%) were classified in anin vitroassay as having a “low adherence ability,” 9 (52.9%) were classified as having a “medium adherence ability,” and 2 (11.8%) were classified as having a “high adherence ability.” TheL. monocytogenesstrains that were predominant and persistent showed significantly better adherence than did strains that were only sporadic, predominant, or persistent (P= 0.0006). Our results suggest that the milking system was exposed to severalL. monocytogenesstrains from different sources. Only 3 strains, however, were successful in persisting within the milking system, suggesting that some strains are more suitable to that particular ecological environment than others.

scholarly journals Molecular Ecology of Listeria monocytogenes: Evidence for a Reservoir in Milking Equipment on a Dairy Farm

2008 ◽  
Vol 75 (5) ◽  
pp. 1315-1323 ◽  
Author(s):  
Alejandra A. Latorre ◽  
Jo Ann S. Van Kessel ◽  
Jeffrey S. Karns ◽  
Michael J. Zurakowski ◽  
Abani K. Pradhan ◽  
...  
Keyword(s):  
New York ◽  
Listeria Monocytogenes ◽  
Environmental Samples ◽  
Molecular Ecology ◽  
New York State ◽  
Dairy Farm ◽  
Bulk Tank Milk ◽  
Fecal Samples ◽  
Milk Samples ◽  
Bulk Tank

ABSTRACT A longitudinal study aimed to detect Listeria monocytogenes on a New York State dairy farm was conducted between February 2004 and July 2007. Fecal samples were collected every 6 months from all lactating cows. Approximately 20 environmental samples were obtained every 3 months. Bulk tank milk samples and in-line milk filter samples were obtained weekly. Samples from milking equipment and the milking parlor environment were obtained in May 2007. Fifty-one of 715 fecal samples (7.1%) and 22 of 303 environmental samples (7.3%) were positive for L. monocytogenes. A total of 73 of 108 in-line milk filter samples (67.6%) and 34 of 172 bulk tank milk samples (19.7%) were positive for L. monocytogenes. Listeria monocytogenes was isolated from 6 of 40 (15%) sampling sites in the milking parlor and milking equipment. In-line milk filter samples had a greater proportion of L. monocytogenes than did bulk tank milk samples (P < 0.05) and samples from other sources (P < 0.05). The proportion of L. monocytogenes-positive samples was greater among bulk tank milk samples than among fecal or environmental samples (P < 0.05). Analysis of 60 isolates by pulsed-field gel electrophoresis (PFGE) yielded 23 PFGE types after digestion with AscI and ApaI endonucleases. Three PFGE types of L. monocytogenes were repeatedly found in longitudinally collected samples from bulk tank milk and in-line milk filters.

scholarly journals Biofilm in milking equipment on a dairy farm as a potential source of bulk tank milk contamination with Listeria monocytogenes

2010 ◽  
Vol 93 (6) ◽  
pp. 2792-2802 ◽  
Author(s):  
A.A. Latorre ◽  
J.S. Van Kessel ◽  
J.S. Karns ◽  
M.J. Zurakowski ◽  
A.K. Pradhan ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Dairy Farm ◽  
Bulk Tank Milk ◽  
Potential Source ◽  
Milk Contamination ◽  
Bulk Tank

scholarly journals Occurrence, Persistence, and Contamination Routes ofListeria monocytogenesGenotypes on Three Finnish Dairy Cattle Farms: a Longitudinal Study

2017 ◽  
Vol 84 (4) ◽  
Author(s):  
Hanna Castro ◽  
Anniina Jaakkonen ◽  
Marjaana Hakkinen ◽  
Hannu Korkeala ◽  
Miia Lindström
Keyword(s):  
Longitudinal Study ◽  
Listeria Monocytogenes ◽  
Dairy Cattle ◽  
Control Strategies ◽  
Dairy Farms ◽  
Bulk Tank Milk ◽  
Content Type ◽  
Bulk Tank ◽  
Contamination Routes ◽  
Cattle Farms

ABSTRACTThe molecular epidemiology ofListeria monocytogeneswas investigated in a longitudinal study of three Finnish dairy farms during 2013 to 2016. A total of 186 bulk tank milk (BTM), 224 milk filter sock (MFS), and 1,702 barn environment samples were analyzed, and isolates ofL. monocytogeneswere genotyped using pulsed-field gel electrophoresis.L. monocytogenesoccurred throughout the year in all sample types, and the prevalence in MFS increased significantly during the indoor season.L. monocytogeneswas more prevalent in MFS (29%) than in BTM (13%) samples. However, the prevalence ofL. monocytogenesvaried more between farms in samples of MFS (13 to 48%) than in BTM (10 to 16%). For each farm, theL. monocytogenesgenotypes detected were classified by persistence (defined as persistent if isolated from ≥3 samples during ≥6 months) and predominance (defined as predominant if >5% prevalence on at least one farm visit). The prevalence of sporadic genotypes was 4 to 5% on all three farms. In contrast, the prevalence of persistent predominant genotypes varied between farms by 4% to 16%. The highest prevalence of persistent predominant genotypes was observed on the farm with the poorest production hygiene. Persistent predominant genotypes were most prevalent on feeding surfaces, water troughs, and floors. Genotypes isolated from the milking system or from cow udders had a greater relative risk of occurring in BTM and MFS than genotypes that only occurred elsewhere in the farm, supporting the hypothesis thatL. monocytogenes is transmitted to milk from contamination on the udder surface or in the milking equipment.IMPORTANCEListeria monocytogenesis a ubiquitous environmental bacterium and the causative agent of a serious foodborne illness, listeriosis. Dairy products are common vehicles of listeriosis, and dairy cattle farms harborL. monocytogenesgenotypes associated with human listeriosis outbreaks. Indeed, dairy cattle farms act as a reservoir ofL. monocytogenes, and the organism is frequently detected in bulk tank milk (BTM) and in the feces of clinically healthy cows. The ecology ofL. monocytogenesin the farm environment is complex and poorly understood. Isolates of the sameL. monocytogenesgenotype can occur in the farm for years, but the factors contributing to the persistence of genotypes on dairy farms are unknown. Knowledge of the persistence patterns and contamination routes ofL. monocytogeneson dairy farms can improve management of the contamination pressure in the farm environment and aid in the development of focused control strategies to reduce BTM contamination.

scholarly journals Mutations in fbiD (Rv2983) as a Novel Determinant of Resistance to Pretomanid and Delamanid in Mycobacterium tuberculosis

2020 ◽  
Vol 65 (1) ◽  
pp. e01948-20
Author(s):  
Dalin Rifat ◽  
Si-Yang Li ◽  
Thomas Ioerger ◽  
Keshav Shah ◽  
Jean-Philippe Lanoix ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Evidence ◽  
Clinical Samples ◽  
Loss Of Function ◽  
Wild Type ◽  
Content Type ◽  
Solid Media ◽  
High Level ◽  
Level Resistance

ABSTRACTThe nitroimidazole prodrugs delamanid and pretomanid comprise one of only two new antimicrobial classes approved to treat tuberculosis (TB) in 50 years. Prior in vitro studies suggest a relatively low barrier to nitroimidazole resistance in Mycobacterium tuberculosis, but clinical evidence is limited to date. We selected pretomanid-resistant M. tuberculosis mutants in two mouse models of TB using a range of pretomanid doses. The frequency of spontaneous resistance was approximately 10−5 CFU. Whole-genome sequencing of 161 resistant isolates from 47 mice revealed 99 unique mutations, of which 91% occurred in 1 of 5 genes previously associated with nitroimidazole activation and resistance, namely, fbiC (56%), fbiA (15%), ddn (12%), fgd (4%), and fbiB (4%). Nearly all mutations were unique to a single mouse and not previously identified. The remaining 9% of resistant mutants harbored mutations in Rv2983 (fbiD), a gene not previously associated with nitroimidazole resistance but recently shown to be a guanylyltransferase necessary for cofactor F420 synthesis. Most mutants exhibited high-level resistance to pretomanid and delamanid, although Rv2983 and fbiB mutants exhibited high-level pretomanid resistance but relatively small changes in delamanid susceptibility. Complementing an Rv2983 mutant with wild-type Rv2983 restored susceptibility to pretomanid and delamanid. By quantifying intracellular F420 and its precursor Fo in overexpressing and loss-of-function mutants, we provide further evidence that Rv2983 is necessary for F420 biosynthesis. Finally, Rv2983 mutants and other F420H2-deficient mutants displayed hypersusceptibility to some antibiotics and to concentrations of malachite green found in solid media used to isolate and propagate mycobacteria from clinical samples.

scholarly journals Prevalence of Salmonellae, Listeria monocytogenes, and Fecal Coliforms in Bulk Tank Milk on US Dairies

2004 ◽  
Vol 87 (9) ◽  
pp. 2822-2830 ◽  
Author(s):  
J.S. Van Kessel ◽  
J.S. Karns ◽  
L. Gorski ◽  
B.J. McCluskey ◽  
M.L. Perdue
Keyword(s):  
Listeria Monocytogenes ◽  
Fecal Coliforms ◽  
Bulk Tank Milk ◽  
Bulk Tank

scholarly journals Evidence for Inhibition of Topoisomerase 1A by Gold(III) Macrocycles and Chelates TargetingMycobacterium tuberculosisandMycobacterium abscessus

2018 ◽  
Vol 62 (5) ◽  
Author(s):  
Rashmi Gupta ◽  
Carolina Rodrigues Felix ◽  
Matthew P. Akerman ◽  
Kate J. Akerman ◽  
Cathryn A. Slabber ◽  
...  
Keyword(s):  
Mycobacterium Abscessus ◽  
Cross Resistance ◽  
Human Pathogens ◽  
Intrinsic Resistance ◽  
Content Type ◽  
Starting Point ◽  
Scalable Synthesis ◽  
High Level ◽  
Novel Drug

ABSTRACTMycobacterium tuberculosisand the fast-growing speciesMycobacterium abscessusare two important human pathogens causing persistent pulmonary infections that are difficult to cure and require long treatment times. The emergence of drug-resistantM. tuberculosisstrains and the high level of intrinsic resistance ofM. abscessuscall for novel drug scaffolds that effectively target both pathogens. In this study, we evaluated the activity of bis(pyrrolide-imine) gold(III) macrocycles and chelates, originally designed as DNA intercalators capable of targeting human topoisomerase types I and II (Topo1 and Topo2), againstM. abscessusandM. tuberculosis. We identified a total of 5 noncytotoxic compounds active against both mycobacterial pathogens under replicatingin vitroconditions. We chose one of these hits, compound 14, for detailed analysis due to its potent bactericidal mode of inhibition and scalable synthesis. The clinical relevance of this compound was demonstrated by its ability to inhibit a panel of diverseM. tuberculosisandM. abscessusclinical isolates. Prompted by previous data suggesting that compound 14 may target topoisomerase/gyrase enzymes, we demonstrated that it lacked cross-resistance with fluoroquinolones, which target theM. tuberculosisgyrase.In vitroenzyme assays confirmed the potent activity of compound 14 against bacterial topoisomerase 1A (Topo1) enzymes but not gyrase. Novel scaffolds like compound 14 with potent, selective bactericidal activity againstM. tuberculosisandM. abscessusthat act on validated but underexploited targets like Topo1 represent a promising starting point for the development of novel therapeutics for infections by pathogenic mycobacteria.

scholarly journals Complete Genome Sequences of Three Bacillus amyloliquefaciens Strains That Inhibit the Growth of Listeria monocytogenes In Vitro

2018 ◽  
Vol 6 (25) ◽  
Author(s):  
Thao D. Tran ◽  
Steven Huynh ◽  
Craig T. Parker ◽  
Robert Hnasko ◽  
Lisa Gorski ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Secondary Metabolites ◽  
Growth Inhibition ◽  
Complete Genome ◽  
Bacillus Amyloliquefaciens ◽  
Gene Clusters ◽  
Genome Sequences ◽  
Multiple Gene ◽  
Content Type

ABSTRACT Here, we report the complete genome sequences of three Bacillus amyloliquefaciens strains isolated from alfalfa, almond drupes, and grapes that inhibited the growth of Listeria monocytogenes strain 2011L-2857 in vitro. We also report multiple gene clusters encoding secondary metabolites that may be responsible for the growth inhibition of L. monocytogenes.

scholarly journals Efficacy of Biocides Used in the Modern Food Industry To Control Salmonella enterica, and Links between Biocide Tolerance and Resistance to Clinically Relevant Antimicrobial Compounds

2012 ◽  
Vol 78 (9) ◽  
pp. 3087-3097 ◽  
Author(s):  
Orla Condell ◽  
Carol Iversen ◽  
Shane Cooney ◽  
Karen A. Power ◽  
Ciara Walsh ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Food Industry ◽  
Multidrug Resistant ◽  
Cross Resistance ◽  
Antimicrobial Compounds ◽  
Cross Tolerance ◽  
Content Type ◽  
Food Grade ◽  
High Level

ABSTRACTBiocides play an essential role in limiting the spread of infectious disease. The food industry is dependent on these agents, and their increasing use is a matter for concern. Specifically, the emergence of bacteria demonstrating increased tolerance to biocides, coupled with the potential for the development of a phenotype of cross-resistance to clinically important antimicrobial compounds, needs to be assessed. In this study, we investigated the tolerance of a collection of susceptible and multidrug-resistant (MDR)Salmonella entericastrains to a panel of seven commercially available food-grade biocide formulations. We explored their abilities to adapt to these formulations and their active biocidal agents, i.e., triclosan, chlorhexidine, hydrogen peroxide, and benzalkonium chloride, after sequential rounds ofin vitroselection. Finally, cross-tolerance of different categories of biocidal formulations, their active agents, and the potential for coselection of resistance to clinically important antibiotics were investigated. Six of seven food-grade biocide formulations were bactericidal at their recommended working concentrations. All showed a reduced activity against both surface-dried and biofilm cultures. A stable phenotype of tolerance to biocide formulations could not be selected. Upon exposure ofSalmonellastrains to an active biocidal compound, a high-level of tolerance was selected for a number ofSalmonellaserotypes. No cross-tolerance to the different biocidal agents or food-grade biocide formulations was observed. Most tolerant isolates displayed changes in their patterns of susceptibility to antimicrobial compounds. Food industry biocides are effective against planktonicSalmonella. When exposed to sublethal concentrations of individual active biocidal agents, tolerant isolates may emerge. This emergence was associated with changes in antimicrobial susceptibilities.

Isolation of Listeria monocytogenes mutants with high-level in vitro expression of host cytosol-induced gene products

2003 ◽  
Vol 48 (6) ◽  
pp. 1537-1551 ◽  
Author(s):  
Lynne M. Shetron-Rama ◽  
Kimberly Mueller ◽  
Juan M. Bravo ◽  
H. G. Archie Bouwer ◽  
Sing Sing Way ◽  
...  
Keyword(s):  
Listeria Monocytogenes ◽  
Gene Products ◽  
In Vitro Expression ◽  
High Level

scholarly journals Relationship between Glycopeptide Production and Resistance in the Actinomycete Nonomuraea sp. ATCC 39727

2014 ◽  
Vol 58 (9) ◽  
pp. 5191-5201 ◽  
Author(s):  
Giorgia Letizia Marcone ◽  
Elisa Binda ◽  
Lucia Carrano ◽  
Mervyn Bibb ◽  
Flavia Marinelli
Keyword(s):  
Antibiotic Resistance ◽  
Gene Dosage ◽  
Antibiotic Production ◽  
Resistance Mechanism ◽  
Biosynthetic Gene Cluster ◽  
Penicillin G ◽  
Glycopeptide Resistance ◽  
Content Type ◽  
High Level

ABSTRACTGlycopeptides and β-lactams inhibit bacterial peptidoglycan synthesis in Gram-positive bacteria; resistance to these antibiotics is studied intensively in enterococci and staphylococci because of their relevance to infectious disease. Much less is known about antibiotic resistance in glycopeptide-producing actinomycetes that are likely to represent the evolutionary source of resistance determinants found in bacterial pathogens.Nonomuraeasp. ATCC 39727, the producer of A40926 (the precursor for the semisynthetic dalbavancin), does not harbor the canonicalvanHAXgenes. Consequently, we investigated the role of the β-lactam-sensitived,d-peptidase/d,d-carboxypeptidase encoded byvanYn, the onlyvan-like gene found in the A40926 biosynthetic gene cluster, in conferring immunity to the antibiotic inNonomuraeasp. ATCC 39727. Taking advantage of the tools developed recently to genetically manipulate this uncommon actinomycete, we variedvanYngene dosage and expressedvanHatAatXatfrom the teicoplanin producerActinoplanes teichomyceticusinNonomuraeasp. ATCC 39727. Knocking outvanYn, complementing avanYnmutant, or duplicatingvanYnhad no effect on growth but influenced antibiotic resistance and, in the cases of complementation and duplication, antibiotic production.Nonomuraeasp. ATCC 39727 was found to be resistant to penicillins, but its glycopeptide resistance was diminished in the presence of penicillin G, which inhibits VanYnactivity. The heterologous expression ofvanHatAatXatincreased A40926 resistance inNonomuraeasp. ATCC 39727 but did not increase antibiotic production, indicating that the level of antibiotic production is not directly determined by the level of resistance. ThevanYn-based self-resistance inNonomuraeasp. ATCC 39727 resembles the glycopeptide resistance mechanism described recently in mutants ofEnterococcus faeciumselectedin vitrofor high-level resistance to glycopeptides and penicillins.

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