@article{dutta_altermann_crespo_olson_siletzky_kathariou_2017, title={Identification of a Campylobacter coli methyltransferase targeting adenines at GATC sites}, volume={364}, DOI={10.1093/femsle/fnw268}, abstractNote={Abstract Campylobacter coli can infect humans and colonize multiple other animals, but its host‐associated genes or adaptations are poorly understood. Adenine methylation at GATC sites, resulting in MboI resistance of genomic DNA, was earlier frequently detected among C. coli from swine but not among turkey‐derived isolates. The underlying genetic basis has remained unknown. Comparative genome sequence analyses of C. coli 6461, a swine‐derived strain with MboI‐resistant DNA, revealed two chromosomal ORFs, 0059 and 0060, encoding a putative DNA methyltransferase and a conserved hypothetical protein, respectively, which were lacking from the genome of the turkey‐derived C. coli strain 11601, which had MboI‐susceptible DNA. To determine whether ORF0059 mediated MboI resistance and hence encoded a putative N6‐adenine DNA methyltransferase, the gene was cloned immediately upstream of a chloramphenicol resistance cassette (cat) and a PCR fragment harboring ORF0059‐cat was transformed into C. coli 11601. The transformants had MboI‐resistant DNA, suggesting a direct role of this gene in methylation of adenines at GATC sites. In silico analyses suggested that the ORF0059‐ORF0060 cassette was more frequent among C. coli from swine than certain other sources (e.g. cattle, humans). Potential impacts of ORF0059‐mediated methylation on C. coli host preference and other adaptations remain to be elucidated.}, number={7}, journal={FEMS Microbiology Letters}, author={Dutta, V. and Altermann, E. and Crespo, M. D. and Olson, J. W. and Siletzky, R. M. and Kathariou, S.}, year={2017} } @article{dutta_elhanafi_osborne_martinez_kathariou_2014, title={Genetic Characterization of Plasmid-Associated Triphenylmethane Reductase in Listeria monocytogenes}, volume={80}, ISSN={["1098-5336"]}, DOI={10.1128/aem.01398-14}, abstractNote={ABSTRACT The enzyme triphenylmethane reductase (TMR) reduces toxic triphenylmethane dyes into colorless, nontoxic derivatives, and TMR-producing microorganisms have been proposed as bioremediation tools. Analysis of the genome of Listeria monocytogenes H7858 (1998-1999 hot dog outbreak) revealed that the plasmid (pLM80) of this strain harboring a gene cassette ( bcrABC ) conferring resistance to benzalkonium chloride (BC) and other quaternary ammonium disinfectants also harbored a gene ( tmr ) highly homologous to TMR-encoding genes from diverse Gram-negative bacteria. The pLM80-associated tmr was located two genes downstream of bcrABC as part of a putative IS 1216 composite transposon. To confirm the role of tmr in triphenylmethane dye detoxification, we introduced various tmr -harboring fragments of pLM80 in a pLM80-cured derivative of strain H7550, from the same outbreak as H7858, and assessed the resistance of the constructs to the triphenylmethane dyes crystal violet (CV) and malachite green. Transcriptional and subcloning data suggest that the regulation of TMR is complex. Constructs harboring fragments spanning bcrABC and tmr were CV resistant, and in such constructs tmr transcription was induced by sublethal levels of either BC or CV. However, constructs harboring only tmr and its upstream intergenic region could also confer resistance to CV, albeit at lower levels. Screening a panel of BC-resistant L. monocytogenes strains revealed that all those harboring bcrABC and adjacent pLM80 sequences, including tmr , were resistant to CV and decolorized this dye. The findings suggest a potential role of TMR as a previously unknown adaptive attribute for environmental persistence of L. monocytogenes . }, number={17}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Dutta, Vikrant and Elhanafi, Driss and Osborne, Jason and Martinez, Mira Rakic and Kathariou, Sophia}, year={2014}, month={Sep}, pages={5379–5385} } @article{dutta_elhanafi_kathariou_2013, title={Conservation and Distribution of the Benzalkonium Chloride Resistance Cassette bcrABC in Listeria monocytogenes}, volume={79}, ISSN={["1098-5336"]}, DOI={10.1128/aem.01751-13}, abstractNote={ABSTRACT Analysis of a panel of 116 Listeria monocytogenes strains of diverse serotypes and sources (clinical, environment of food processing plants, and food) revealed that all but one of the 71 benzalkonium chloride-resistant (BC r ) isolates harbored bcrABC , previously identified on a large plasmid (pLM80) of the 1998-1999 hot dog outbreak strain H7858. In contrast, bcrABC was not detected among BC-susceptible (BC s ) isolates. The bcrABC sequences were highly conserved among strains of different serotypes, but variability was noted in sequences flanking bcrABC . The majority of the BC r isolates had either the pLM80-type of organization of the bcrABC region or appeared to harbor bcrABC on the chromosome, adjacent to novel sequences. Transcription of bcrABC was induced by BC (10 μg/ml) in strains of different serotypes and diverse bcrABC region organization. These findings reveal widespread dissemination of bcrABC across BC r L. monocytogenes strains regardless of serotype and source, while also suggesting possible mechanisms of bcrABC dissemination across L. monocytogenes genomes. }, number={19}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Dutta, Vikrant and Elhanafi, Driss and Kathariou, Sophia}, year={2013}, month={Oct}, pages={6067–6074} } @article{ratani_siletzky_dutta_yildirim_osborne_lin_hitchins_ward_kathariou_2012, title={Heavy Metal and Disinfectant Resistance of Listeria monocytogenes from Foods and Food Processing Plants}, volume={78}, ISSN={["0099-2240"]}, DOI={10.1128/aem.01553-12}, abstractNote={ABSTRACT The persistence of Listeria monocytogenes in food processing plants and other ecosystems reflects its ability to adapt to numerous stresses. In this study, we investigated 138 isolates from foods and food processing plants for resistance to the quaternary ammonium disinfectant benzalkonium chloride (BC) and to heavy metals (cadmium and arsenic). We also determined the prevalence of distinct cadmium resistance determinants ( cadA1 , cadA2 , and cadA3 ) among cadmium-resistant isolates. Most BC-resistant isolates were resistant to cadmium as well. Arsenic resistance was encountered primarily in serotype 4b and was an attribute of most isolates of the serotype 4b epidemic clonal group ECIa. Prevalence of the known cadmium resistance determinants was serotype associated: cadA1 was more common in isolates of serotypes 1/2a and 1/2b than 4b, while cadA2 was more common in those of serotype 4b. A subset (15/77 [19%]) of the cadmium-resistant isolates lacked the known cadmium resistance determinants. Most of these isolates were of serotype 4b and were also resistant to arsenic, suggesting novel determinants that may confer resistance to both cadmium and arsenic in these serotype 4b strains. The findings may reflect previously unrecognized components of the ecological history of different serotypes and clonal groups of L. monocytogenes , including exposures to heavy metals and disinfectants. }, number={19}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Ratani, Shakir S. and Siletzky, Robin M. and Dutta, Vikrant and Yildirim, Suleyman and Osborne, Jason A. and Lin, Wen and Hitchins, Anthony D. and Ward, Todd J. and Kathariou, Sophia}, year={2012}, month={Oct}, pages={6938–6945} } @article{huff_dutta_huff_rath_2011, title={Effects of dietary yeast extract on turkey stress response and heterophil oxidative burst activity}, volume={52}, ISSN={["1466-1799"]}, DOI={10.1080/00071668.2011.600753}, abstractNote={1. Effective nutritional approaches to counteract the negative effects of stress may provide food animal producers with useful alternatives to antibiotics. In this study, turkeys were fed on a standard diet, or the same diet supplemented with yeast extract (YE), to determine if YE would improve disease resistance in a stress model. 2. At 16 weeks of age, half of the birds were exposed to a bacterial challenge using a coarse spray of the pen environment. A subset of control and challenged birds was also treated with dexamethasone (Dex) prior to challenge (Dex/challenge). At 18 weeks, another subset was subjected to a 12 h transport stress protocol (Challenge/transport). All birds were bled and necropsied the morning after transport. The numbers and proportions of blood cells and the heterophil oxidative burst activity (OBA) were determined. Serum corticosterone (Cort) levels of male birds were measured using a commercial ELISA kit. Body weight and gain were increased by YE during week 1. 3. YE decreased mortality and bacterial isolation following Dex/challenge only in females. Cort levels in male turkeys were decreased by YE and Dex treatment. OBA was higher in males and in birds given YE and was reduced by challenge and transport. 4. These results suggest there may be gender differences in the turkey stress response and that dietary YE has potential for modulating the impact of stress on innate immunity of turkeys.}, number={4}, journal={BRITISH POULTRY SCIENCE}, author={Huff, G. R. and Dutta, V. and Huff, W. E. and Rath, N. C.}, year={2011}, pages={446–455} } @article{rakic-martinez_drevets_dutta_katic_kathariou_2011, title={Listeria monocytogenes Strains Selected on Ciprofloxacin or the Disinfectant Benzalkonium Chloride Exhibit Reduced Susceptibility to Ciprofloxacin, Gentamicin, Benzalkonium Chloride, and Other Toxic Compounds}, volume={77}, ISSN={["1098-5336"]}, DOI={10.1128/aem.05941-11}, abstractNote={ABSTRACT Listeria monocytogenes is a leading agent for severe food-borne illness and death in the United States and other nations. Even though drug resistance has not yet threatened therapeutic interventions for listeriosis, selective pressure associated with exposure to antibiotics and disinfectants may result in reduced susceptibility to these agents. In this study, selection of several L. monocytogenes strains on either ciprofloxacin (2 μg/ml) or the quaternary ammonium disinfectant benzalkonium chloride (BC; 10 μg/ml) led to derivatives with increased MICs not only to these agents but also to several other toxic compounds, including gentamicin, the dye ethidium bromide, and the chemotherapeutic drug tetraphenylphosphonium chloride. The spectrum of compounds to which these derivatives exhibited reduced susceptibility was the same regardless of whether they were selected on ciprofloxacin or on BC. Inclusion of strains harboring the large plasmid pLM80 revealed that MICs to ciprofloxacin and gentamicin did not differ between the parental and plasmid-cured strains. However, ciprofloxacin-selected derivatives of pLM80-harboring strains had higher MICs than those derived from the plasmid-cured strains. Susceptibility to the antimicrobials was partially restored in the presence of the potent efflux inhibitor reserpine. Taken together, these data suggest that mutations in efflux systems are responsible for the multidrug resistance phenotype of strains selected on ciprofloxacin or BC. }, number={24}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Rakic-Martinez, Mira and Drevets, Douglas A. and Dutta, Vikrant and Katic, Vera and Kathariou, Sophia}, year={2011}, month={Dec}, pages={8714–8721} } @article{elhanafi_dutta_kathariou_2010, title={Genetic Characterization of Plasmid-Associated Benzalkonium Chloride Resistance Determinants in a Listeria monocytogenes Strain from the 1998-1999 Outbreak}, volume={76}, ISSN={["1098-5336"]}, DOI={10.1128/aem.02056-10}, abstractNote={ABSTRACT Quaternary ammonium compounds such as benzalkonium chloride (BC) are widely used as disinfectants in both food processing and medical environments. BC-resistant strains of Listeria monocytogenes have been implicated in multistate outbreaks of listeriosis and have been frequently isolated from food processing plants. However, the genetic basis for BC resistance in L. monocytogenes remains poorly understood. In this study, we have characterized a plasmid (pLM80)-associated BC resistance cassette in L. monocytogenes H7550, a strain implicated in the 1998-1999 multistate outbreak involving contaminated hot dogs. The BC resistance cassette ( bcrABC ) restored resistance to BC (MIC, 40 μg/ml) in a plasmid-cured derivative of H7550. All three genes of the cassette were essential for imparting BC resistance. The transcription of H7550 BC resistance genes was increased under sublethal (10 μg/ml) BC exposure and was higher at reduced temperatures (4, 8, or 25°C) than at 37°C. The level of transcription was higher at 10 μg/ml than at 20 or 40 μg/ml. In silico analysis suggested that the BC resistance cassette was harbored by an IS 1216 composite transposon along with other genes whose functions are yet to be determined. The findings from this study will further our understanding of the adaptations of this organism to disinfectants such as BC and may contribute to the elucidation of possible BC resistance dissemination in L. monocytogenes . }, number={24}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Elhanafi, Driss and Dutta, Vikrant and Kathariou, Sophia}, year={2010}, month={Dec}, pages={8231–8238} } @article{huff_huff_dutta_johnson_nannapaneni_2008, title={Pathogenicity of Listeria monocytogenes Scott A After Oral and Oculonasal Challenges of Day-Old Turkey Poults}, volume={52}, ISSN={["1938-4351"]}, DOI={10.1637/8244-013008-Reg.1}, abstractNote={Abstract Listeria monocytogenes is a ubiquitous, environmental pathogen that has contaminated poultry ready-to-eat products resulting in large-scale recalls. Research is needed to determine the source of product and processing plant contamination with L. monocytogenes. The purpose of this study was to compare the oral and oculonasal routes of infection on the pathogenicity of L. monocytogenes in turkey poults under different housing conditions. One-day-old turkey poults were challenged by either route with the Scott A strain of L. monocytogenes and placed either in paper-lined battery-brooder cages for 1 wk or in floor pens on fresh pine-shaving litter. On day 7, birds challenged in battery cages were transferred to floor pens. Challenge by the oculonasal route resulted in higher mortality (P  =  0.05) and lower body weights (P < 0.0001) compared with both nonchallenged controls and those challenged by the oral route. Birds contained in battery cages for 1 wk had higher mortality (P  =  0.002) and higher body weights (P < 0.0001) compared with floor-pen–reared birds. Using direct plating, the challenge strain was isolated from the gall bladder, brain, and knee joint of only one dead poult challenged by the oculonasal route. These results suggest that day-old turkey poults may be more susceptible to an oculonasal challenge with L. monocytogenes than to an oral challenge and that containment in battery cages for the first week increased contact exposure to the challenge. Patogenicidad de Listeria monocytogenes Scott A luego del desafío oral y oculonasal de pavitos de un día de edad. La Listeria monocytogenes es un patógeno ambiental ubicuo que ha contaminado productos avícolas listos para consumir resultando en retiros masivos del mercado. Se requiere investigación para determinar el origen de la contaminación con L. monocytogenes de productos y de la planta de procesamiento. El propósito de este estudio fue comparar el efecto de las rutas de infección oral y óculonasal en la patogenicidad de L. monocytogenes en pavos jóvenes bajo diferentes condiciones de crianza. Se desafiaron pavitos de un día de edad con L. monocytogenes por alguna de las dos rutas y se colocaron en jaulas de crianza con papel en el piso por una semana o se colocaron en corrales con cama de viruta de pino. Al día siete, las aves desafiadas en las jaulas se transfirieron a los corrales en piso. El desafío por la vía óculonasal resultó en mayor mortalidad (P  =  0.05) y en pesos corporales mas bajos (P < 0.0001), en comparación con los controles no desafiados y las aves desafiadas por la vía oral. Las aves mantenidas en las jaulas por una semana presentaron una mayor mortalidad (P  =  0.002) y mayor peso corporal (P < 0.0001) que las aves criadas en el piso. Utilizando siembra directa, se aisló la cepa de desafío de la vesícula biliar, cerebro y articulación de la rodilla de sólo una de las aves muertas desafiada por la vía óculonasal. Estos resultados sugieren que los pavitos de un día de edad pueden ser más susceptibles a un desafío óculonasal con L. monocytogenes que a un desafío oral y que el confinamiento en jaulas durante la primera semana incrementó la exposición por contacto al desafío. Abbreviations: Baso = basophils; CFU = colony forming units; EDTA = ethylenediaminetetraacetic acid; Eos = eosinophils; FAC = ferric ammonium citrate; Het = heterophils; Lym = lymphocytes; Mono = monocytes; plt = platelets; TPB = tryptose phosphate broth; UVM = University of Vermont medium; WBC = white blood cells}, number={3}, journal={AVIAN DISEASES}, author={Huff, G. R. and Huff, W. E. and Dutta, V. and Johnson, M. G. and Nannapaneni, R.}, year={2008}, month={Sep}, pages={444–450} }