@article{good_miller_niedermeyer_osborne_siletzky_carver_kathariou_2019, title={Strain-Specific Differences in Survival of Campylobacter spp. in Naturally Contaminated Turkey Feces and Water}, volume={85}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.01579-19}, abstractNote={ Campylobacter jejuni and Campylobacter coli are leading foodborne pathogens, with poultry as a major reservoir. Due to their growth requirements, these Campylobacter spp. may be unable to replicate once excreted by their avian hosts, but their survival in feces and the environment is critical for transmission in the farm ecosystem. Reducing the prevalence of Campylobacter -positive flocks can have major impacts in controlling both contamination of poultry products and environmental dissemination of the pathogens. However, understanding the capacity of these pathogens to survive in transmission-relevant vehicles such as feces and farmhouse water remains poorly understood, and little information is available on species- and strain-associated differences in survival. Here, we employed model conditions to investigate the survival of C. jejuni and C. coli from naturally colonized turkey flocks, and with diverse genotypes and antimicrobial resistance profiles, in turkey feces and in farmhouse water. }, number={22}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Good, Lesley and Miller, William G. and Niedermeyer, Jeffrey and Osborne, Jason and Siletzky, Robin M. and Carver, Donna and Kathariou, Sophia}, year={2019}, month={Nov} } @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{lee_ward_graves_tarr_siletzky_kathariou_2014, title={Population Structure of Listeria monocytogenes Serotype 4b Isolates from Sporadic Human Listeriosis Cases in the United States from 2003 to 2008}, volume={80}, ISSN={["1098-5336"]}, DOI={10.1128/aem.00454-14}, abstractNote={ABSTRACT Listeria monocytogenes can cause severe food-borne disease (listeriosis). Numerous outbreaks have involved three serotype 4b epidemic clones (ECs): ECI, ECII, and ECIa. However, little is known about the population structure of L. monocytogenes serotype 4b from sporadic listeriosis in the United States, even though most cases of human listeriosis are in fact sporadic. Here we analyzed 136 serotype 4b isolates from sporadic cases in the United States, 2003 to 2008, utilizing multiple tools including multilocus genotyping, pulsed-field gel electrophoresis, and sequence analysis of the inlAB locus. ECI, ECII, and ECIa were frequently encountered (32, 17, and 7%, respectively). However, annually 30 to 68% of isolates were outside these ECs, and several novel clonal groups were identified. An estimated 33 and 17% of the isolates, mostly among the ECs, were resistant to cadmium and arsenic, respectively, but resistance to benzalkonium chloride was uncommon (3%) among the sporadic isolates. The frequency of clonal groups fluctuated within the 6-year study period, without consistent trends. However, on several occasions, temporal clusters of isolates with indistinguishable genotypes were detected, suggesting the possibility of hidden multistate outbreaks. Our analysis suggests a complex population structure of serotype 4b L. monocytogenes from sporadic disease, with important contributions by ECs and several novel clonal groups. Continuous monitoring will be needed to assess long-term trends in clonality patterns and population structure of L. monocytogenes from sporadic listeriosis. }, number={12}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Lee, Sangmi and Ward, Todd J. and Graves, Lewis M. and Tarr, Cheryl L. and Siletzky, Robin M. and Kathariou, Sophia}, year={2014}, month={Jun}, pages={3632–3644} } @article{lee_rakic-martinez_graves_ward_siletzky_kathariou_2013, title={Genetic Determinants for Cadmium and Arsenic Resistance among Listeria monocytogenes Serotype 4b Isolates from Sporadic Human Listeriosis Patients}, volume={79}, ISSN={["1098-5336"]}, DOI={10.1128/aem.03551-12}, abstractNote={ABSTRACT In Listeria monocytogenes serotype 4b isolates from sporadic listeriosis, heavy metal resistance was primarily encountered in certain clonal groups (ECI, ECII, and ECIa). All arsenic-resistant isolates harbored the arsenic resistance cassette previously identified in pLI100; ECIa harbored additional arsenic resistance genes and a novel cadmium resistance determinant in a conserved chromosomal locus. }, number={7}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Lee, Sangmi and Rakic-Martinez, M. and Graves, L. M. and Ward, T. J. and Siletzky, R. M. and Kathariou, S.}, year={2013}, month={Apr}, pages={2471–2476} } @article{crespo_olson_altermann_siletzky_kathariou_2012, title={Chromosomal tet(O)-Harboring Regions in Campylobacter coli Isolates from Turkeys and Swine}, volume={78}, ISSN={["0099-2240"]}, DOI={10.1128/aem.02258-12}, abstractNote={ABSTRACT In turkey-derived Campylobacter coli isolates of a unique lineage (cluster II), the tetracycline resistance determinant tet (O) was chromosomal and was part of a gene cassette (transposon) interrupting a Campylobacter jejuni -associated putative citrate transporter gene. In contrast, the swine-derived C. coli strain 6461 harbored a chromosomal tet (O) in a different genomic location. }, number={23}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Crespo, M. D. and Olson, J. W. and Altermann, E. and Siletzky, R. M. and Kathariou, S.}, year={2012}, month={Dec}, pages={8488–8491} } @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{thanissery_kathariou_siletzky_smith_2012, title={Microbiology of prechill carcasses from medium- and fast-growing pastured broiler chicken strains}, volume={21}, ISSN={["1056-6171"]}, DOI={10.3382/japr.2012-00548}, abstractNote={SUMMARY Consumer demand is increasing for free-range and organic poultry products. The USDA requires that postchill broilers be tested for Escherichia coli, Salmonella, and Campylobacter. Microbiological data are limited on the fast-growing Cornish cross (CX) chickens or the medium-growing Freedom Rangers (FR), 2 predominant strains of pastured broilers grown in the Southeast region of the United States. The objective of the present study was to compare the levels of total coliforms and E. coli, as well as the prevalence of Campylobacter and Salmonella, in pastured CX and FR strains. In each of 2 trials, 40 CX and 40 FR broilers were raised together on pasture with water and supplemental feed. At market weight, birds were processed and 20 prechill carcasses of each strain were evaluated for enumeration of total coliforms and E. coli, as well as the prevalence of Salmonella. Cecal contents were direct plated for Campylobacter detection. Mean counts for total coliforms and E. coli (expressed in log cfu/mL) were 3.8 and 3.4 for FR, which was significantly lower (P < 0.05) than the 4.1 and 3.7 for the CX group. The Salmonella prevalence on carcasses was not different in trial 1 because of strain, but the FR strain had significantly lower Salmonella than the CX strain (50 vs. 100%, respectively) in trial 2. Irrespective of strain, the prevalence of Campylobacter was high (95% for FR vs. 100% for CX). In trial 2, although the medium-growing FR showed lower levels of total coliforms and E. coli, as well as a lower prevalence of Salmonella, even when reared with fast-growing CX, it is not known whether this could have been due to an inherent ability of FR to resist colonization or the benefit from longer residence on pasture.}, number={3}, journal={JOURNAL OF APPLIED POULTRY RESEARCH}, author={Thanissery, R. and Kathariou, S. and Siletzky, R. M. and Smith, D. P.}, year={2012}, month={Sep}, pages={623–629} } @article{lee_ward_siletzky_kathariou_2012, title={Two Novel Type II Restriction-Modification Systems Occupying Genomically Equivalent Locations on the Chromosomes of Listeria monocytogenes Strains}, volume={78}, ISSN={["0099-2240"]}, DOI={10.1128/aem.07203-11}, abstractNote={ABSTRACT Listeria monocytogenes is responsible for the potentially life-threatening food-borne disease listeriosis. One epidemic-associated clonal group of L. monocytogenes , epidemic clone I (ECI), harbors a Sau3AI-like restriction-modification (RM) system also present in the same genomic region in certain strains of other lineages. In this study, we identified and characterized two other, novel type II RM systems, LmoJ2 and LmoJ3, at this same locus. LmoJ2 and LmoJ3 appeared to recognize GCWGC (W = A or T) and GCNGC, respectively. Both RM systems consisted of genes with GC content below the genome average and were in the same genomic region in strains of different serotypes and lineages, suggesting site-specific horizontal gene transfer. Genomic DNA from the LmoJ2 and LmoJ3 strains grown at various temperatures (4 to 42°C) was resistant to digestion with restriction enzymes recognizing GCWGC or GCNGC, indicating that the methyltransferases were expressed under these conditions. Phages propagated in an LmoJ2-harboring strain exhibited moderately increased infectivity for this strain at 4 and 8°C but not at higher temperatures, while phages propagated in an LmoJ3 strain had dramatically increased infectivity for this strain at all temperatures. Among the sequenced Listeria phages, lytic phages possessed significantly fewer recognition sites for these RM systems than lysogenic phages, suggesting that in lytic phages sequence content evolved toward reduced susceptibility to such RM systems. The ability of LmoJ2 and LmoJ3 to protect against phages may affect the efficiency of phages as biocontrol agents for L. monocytogenes strains harboring these RM systems. }, number={8}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Lee, Sangmi and Ward, T. J. and Siletzky, R. M. and Kathariou, S.}, year={2012}, month={Apr}, pages={2623–2630} } @article{lee_ward_graves_wolf_sperry_siletzky_kathariou_2012, title={Atypical Listeria monocytogenes Serotype 4b Strains Harboring a Lineage II-Specific Gene Cassette}, volume={78}, ISSN={["0099-2240"]}, DOI={10.1128/aem.06378-11}, abstractNote={ABSTRACT Listeria monocytogenes is the etiological agent of listeriosis, a severe food-borne illness. The population of L. monocytogenes is divided into four lineages (I to IV), and serotype 4b in lineage I has been involved in numerous outbreaks. Several serotype 4b epidemic-associated clonal groups (ECI, -II, and -Ia) have been identified. In this study, we characterized a panel of strains of serotype 4b that produced atypical results with a serotype-specific multiplex PCR and possessed the lmo0734 to lmo0739 gene cassette that had been thought to be specific to lineage II. The cassette was harbored in a genomically syntenic locus in these isolates and in lineage II strains. Three distinct clonal groups (groups 1 to 3) were identified among these isolates based on single-nucleotide polymorphism-based multilocus genotyping (MLGT) and DNA hybridization data. Groups 1 and 2 had MLGT haplotypes previously encountered among clinical isolates and were composed of clinical isolates from multiple states in the United States. In contrast, group 3 consisted of clinical and environmental isolates solely from North Carolina and exhibited a novel haplotype. In addition, all group 3 isolates had DNA that was resistant to MboI, suggesting methylation of adenines at GATC sites. Sequence analysis of the lmo0734 to lmo0739 gene cassette from two strains (group 1 and group 3) revealed that the genes were highly conserved (>99% identity). The data suggest relatively recent horizontal gene transfer from lineage II L. monocytogenes into L. monocytogenes serotype 4b and subsequent dissemination among at least three distinct clonal groups of L. monocytogenes serotype 4b, one of which exhibits restrictions in regional distribution. }, number={3}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Lee, Sangmi and Ward, Todd J. and Graves, Lewis M. and Wolf, Leslie A. and Sperry, Kate and Siletzky, Robin M. and Kathariou, Sophia}, year={2012}, month={Feb}, pages={660–667} } @article{rahimi_kathariou_grimes_siletzky_2011, title={Effect of direct-fed microbials on performance and Clostridium perfringens colonization of turkey poults}, volume={90}, ISSN={["1525-3171"]}, DOI={10.3382/ps.2011-01342}, abstractNote={Clostridium perfringens is recognized as an enteric pathogen in humans, domestic animals, and livestock. This organism is associated with necrotic enteritis, gangrenous dermatitis, clostridial dermatitis (turkeys), and gizzard erosions in poultry. This study was conducted to evaluate the effectiveness of a direct-fed microbial (DFM), Primalac (Star Labs, Clarksdale, MO), in preventing intestinal colonization of turkey poults with C. perfringens. One-day-old turkey poults (n = 128) were randomly divided into 4 treatments with 4 replicates (8 birds/pen). Treatments were as follows: 1) basal diet without DFM (C); 2) basal diet supplemented with Primalac (1.5 kg/ton; PM); 3) basal diet with poults gavaged with C. perfringens (CCP); and 4) basal diet supplemented with Primalac and poults gavaged with C. perfringens (PMCP). Feed and water were provided ad libitum throughout the trials, and birds were inoculated with C. perfringens (10(8)cfu/mL) on d 3 and 7. On d 21, 2 birds/pen were killed, spleen and bursa of Fabricius were collected and weighed, and cecal contents were used for C. perfringens enumeration. Feed consumption, BW, and feed conversion were calculated throughout the trial (weekly and cumulatively). Data were analyzed using GLM of SAS (SAS Institute, Cary, NC; P < 0.05). Among the inoculated groups, birds fed the DFM-supplemented diet had significantly lower cecal C. perfringens counts than the birds fed the diet without the DFM. The C. perfringens (log(10) cfu/g) in ceca were as follows: C, 5.88; CCP, 7.26; PM, 5.35; PMCP, 6.19 ± 0.36. No differences were observed for BW (814 ± 11 g), feed conversion (1.33 ± 0.03), organ weights, or relative organ weights. Further studies are needed to fully ascertain the potential of using DFM to reduce the numbers of C. perfringens in the gastrointestinal tract of turkey poults.}, number={11}, journal={POULTRY SCIENCE}, author={Rahimi, S. and Kathariou, S. and Grimes, J. L. and Siletzky, R. M.}, year={2011}, month={Nov}, pages={2656–2662} } @article{yildirim_elhanafi_lin_hitchins_siletzky_kathariou_2010, title={Conservation of Genomic Localization and Sequence Content of Sau3AI-Like Restriction-Modification Gene Cassettes among Listeria monocytogenes Epidemic Clone I and Selected Strains of Serotype 1/2a}, volume={76}, ISSN={["1098-5336"]}, DOI={10.1128/aem.00648-10}, abstractNote={ABSTRACTListeria monocytogenesis a food-borne pathogen with a clonal population structure and apparently limited gene flow between strains of different lineages. Strains of epidemic clone I (ECI) have been responsible for numerous outbreaks and invariably have DNA that is resistant to digestion by Sau3AI, suggesting methylation of cytosine at GATC sites. A putative restriction-modification (RM) gene cassette has been identified in the genome of the ECI strain F2365 and all other tested ECI strains but is absent from other strains of the same serotype (4b). Homologous RM cassettes have not been reported amongL. monocytogenesisolates of other serotypes. Furthermore, conclusive evidence for the involvement of this RM cassette in the Sau3AI resistance phenotype of ECI strains has been lacking. In this study, we describe a highly conserved RM cassette in certain strains of serotypes 1/2a and 4a that have Sau3AI-resistant DNA. In these strains the RM cassette was in the same genomic location as in the ECI reference strain F2365. The cassette included a gene encoding a putative recombinase, suggesting insertion via site-specific recombination. Deletion of the RM cassette in the ECI strain F2365 and the serotype 1/2a strain A7 rendered the DNA of both strains susceptible to Sau3AI digestion, providing conclusive evidence that the cassette includes a gene required for methylation of cytosine at GATC sites in both strains. The findings suggest that, in addition to its presence in ECI strains, this RM cassette and the accompanying genomic DNA methylation is also encountered among selected strains of other lineages.}, number={16}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Yildirim, Suleyman and Elhanafi, Driss and Lin, Wen and Hitchins, Anthony D. and Siletzky, Robin M. and Kathariou, S.}, year={2010}, month={Aug}, pages={5577–5584} } @article{cheng_kim_lee_siletzky_kathariou_2010, title={DNA Probes for Unambiguous Identification of Listeria monocytogenes Epidemic Clone II Strains}, volume={76}, ISSN={["1098-5336"]}, DOI={10.1128/aem.03064-09}, abstractNote={ABSTRACT Listeria monocytogenes epidemic clone II (ECII) strains have been responsible for two major multistate outbreaks of food-borne listeriosis in the United States, but their prevalence and ecology remain poorly understood. In this study, we describe DNA probes that unambiguously identify this clonal group. These probes were able to differentiate ECII strains of outbreak, sporadic, or environmental origin from other L. monocytogenes strains of the same serotype (4b). }, number={9}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Cheng, Ying and Kim, J. -W. and Lee, S. and Siletzky, R. M. and Kathariou, S.}, year={2010}, month={May}, pages={3061–3068} } @article{wright_wilson_miller_mandrell_siletzky_kathariou_2010, title={Differences in Methylation at GATC Sites in Genomic DNA of Campylobacter coli from Turkeys and Swine}, volume={76}, ISSN={["0099-2240"]}, DOI={10.1128/aem.00934-10}, abstractNote={ABSTRACT A significant fraction (46/108, 43%) of swine isolates of Campylobacter coli but none of 81 isolates of C. coli from turkeys had genomic DNA that was resistant to digestion by MboI, suggesting methylation of adenines at GATC sites. No consistent association was noted between antimicrobial resistance and MboI resistance. Seven swine-associated multilocus sequence typing-based sequence types (STs) were detected among multiple isolates with MboI-resistant DNA. The data suggest host-associated DNA modification system(s) specific for adenine at GATC sites in C. coli from swine. }, number={21}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Wright, Sandra and Wilson, Simone and Miller, William G. and Mandrell, Robert E. and Siletzky, Robin M. and Kathariou, Sophia}, year={2010}, month={Nov}, pages={7314–7317} } @article{mullapudi_siletzky_kathariou_2010, title={Diverse Cadmium Resistance Determinants in Listeria monocytogenes Isolates from the Turkey Processing Plant Environment}, volume={76}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.01751-09}, abstractNote={ABSTRACT Two different cadA cadmium resistance determinants ( cadA1 , first identified in Tn 5422 , and cadA2 , associated with pLM80) were detected among cadmium-resistant Listeria monocytogenes strains from turkey processing plants. Prevalence of cadA1 versus cadA2 was serotype associated. Cadmium-resistant isolates that were also resistant to benzalkonium chloride (BC) were more likely to harbor cadA2 alone or together with cadA1 than isolates that were cadmium resistant but BC susceptible. }, number={2}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Mullapudi, S. and Siletzky, R. M. and Kathariou, S.}, year={2010}, month={Jan}, pages={627–630} } @article{gu_siletzky_wright_islam_kathariou_2009, title={Antimicrobial Susceptibility Profiles and Strain Type Diversity of Campylobacter jejuni Isolates from Turkeys in Eastern North Carolina}, volume={75}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.02012-08}, abstractNote={ABSTRACT Campylobacter jejuni is one of the most common bacterial causes of human gastroenteritis, and recent findings suggest that turkeys are an important reservoir for this organism. In this study, 80 C. jejuni isolates from eastern North Carolina were characterized for resistance to nine antimicrobials, and strain types were determined by fla typing, pulsed-field gel electrophoresis (PFGE) with SmaI and KpnI, and (for 41 isolates) multilocus sequence typing (MLST). PFGE analysis suggested that many of the isolates (37/40 [ca. 93%]) in a major genomic cluster had DNA that was partially methylated at SmaI sites. Furthermore, 12/40 (30%) of the isolates in this cluster were completely resistant to digestion by KpnI, suggesting methylation at KpnI sites. MLST of 41 isolates identified 10 sequence types (STs), of which 4 were new. Three STs (ST-1839, ST-2132 and the new ST-2934) were predominant and were detected among isolates from different farms. The majority of the isolates (74%) were resistant to three or more antimicrobials, and resistance to ciprofloxacin was common (64%), whereas resistance to the other drug of choice for treatment of human campylobacteriosis, erythromycin, was never encountered. Most (33/34) of the kanamycin-resistant isolates were also resistant to tetracycline; however, only ca. 50% of the tetracycline-resistant isolates were also kanamycin resistant. Isolates with certain antimicrobial resistance profiles had identical or closely related strain types. Overall, the findings suggest dissemination of certain clonal groups of C. jejuni isolates in the turkey production industry of this region. }, number={2}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Gu, Weimin and Siletzky, Robin M. and Wright, Sandra and Islam, Mohammed and Kathariou, Sophia}, year={2009}, month={Jan}, pages={474–482} } @article{mullapudi_siletzky_kathariou_2008, title={Heavy-metal and benzalkonium chloride resistance of Listeria monocytogenes isolates from the environment of turkey-processing plants}, volume={74}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.02426-07}, abstractNote={ABSTRACT The resistance of Listeria monocytogenes to cadmium and arsenic has been used extensively for strain subtyping. However, limited information is available on the prevalence of such resistance among isolates from the environment of food-processing plants. In addition, it is not known whether the resistance of such isolates to heavy metals may correlate with resistance to quaternary ammonium compounds extensively used as disinfectants in the food-processing industry. In this study, we characterized 192 L. monocytogenes isolates (123 putative strains) from the environment of turkey-processing plants in the United States for resistance to cadmium and arsenic and to the quaternary ammonium disinfectant benzalkonium chloride (BC). Resistance to cadmium was significantly more prevalent among strains of serotypes 1/2a (or 3a) and 1/2b (or 3b) (83% and 74%, respectively) than among strains of the serotype 4b complex (19%). Resistance to BC was encountered among 60% and 51% of the serotype 1/2a (or 3a) and 1/2b (or 3b) strains, respectively, and among 7% of the strains of the serotype 4b complex. All BC-resistant strains were also resistant to cadmium, although the reverse was not always the case. In contrast, no correlation was found between BC resistance and resistance to arsenic, which overall was low (6%). Our findings suggest that the processing environment of turkey-processing plants may constitute a reservoir for L. monocytogenes harboring resistance to cadmium and to BC and raise the possibility of common genetic elements or mechanisms mediating resistance to quaternary ammonium disinfectants and to cadmium in L. monocytogenes . }, number={5}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Mullapudi, S. and Siletzky, R. M. and Kathariou, S.}, year={2008}, month={Mar}, pages={1464–1468} } @article{kim_siletzky_kathariou_2008, title={Host Ranges of Listeria-Specific Bacteriophages from the Turkey Processing Plant Environment in the United States}, volume={74}, ISSN={["1098-5336"]}, DOI={10.1128/AEM.01282-08}, abstractNote={ABSTRACT Even though at least 400 Listeria phages have been isolated from various sources, limited information is available on phages from the food processing plant environment. Phages in the processing plant environment may play critical roles in determining the Listeria population that becomes established in the plant. In this study, we pursued the isolation of Listeria -specific phages from environmental samples from four turkey processing plants in the United States. These environmental samples were also utilized to isolate Listeria spp. Twelve phages were isolated and classified into three groups in terms of their host range. Of these, nine (group 1) showed a wide host range, including multiple serotypes of Listeria monocytogenes , as well as other Listeria spp. ( L. innocua , L. welshimeri , L. seeligeri , and L. ivanovii ). The remaining phages mostly infected L. monocytogenes serotype 4b as well as L. innocua , L. ivanovii , and/or L. welshimeri . All but one of the strains of the serotype 4b complex (4b, 4d, 4e) from the processing plant environment could be readily infected by the wide-host-range phages isolated from the environment of the processing plants. However, many strains of other serotypes (1/2a [or 3a] and 1/2b [or 3b]), which represented the majority of L. monocytogenes strains isolated from the environmental samples, were resistant to infection by these phages. Experiments with two phage-resistant strains showed reduced phage adsorption onto the host cells. These findings suggest that phage resistance may be an important component of the ecology of L. monocytogenes in the turkey processing plants. }, number={21}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={Kim, Jae-Won and Siletzky, Robin M. and Kathariou, Sophia}, year={2008}, month={Nov}, pages={6623–6630} } @article{wright_carver_siletzky_romine_morrow_kathariou_2008, title={Longitudinal study of prevalence of Campylobacter jejuni and Campylobacter coli from turkeys and swine grown in close proximity}, volume={71}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X-71.9.1791}, abstractNote={Eastern North Carolina is a major contributor to both turkey and swine production in the United States. In this region, turkeys and swine are frequently grown in close proximity and by common growers. To further characterize colonization of turkeys and swine with Campylobacter in such a setting, we investigated the prevalence of thermophilic campylobacters in eight paired operations involving turkey farms in close proximity to finishing swine farms. All 15 surveyed flocks and 15 herds were Campylobacter positive at one or more sampling times. Campylobacter was isolated from 1,310 (87%) of the 1,512 turkey samples and 1,116 (77%) of the 1,448 swine samples. Most (> 99%) campylobacters from swine samples were Campylobacter coli, found in 59 to 97% of the samples from the different herds. Both Campylobacterjejuni and C. coli were recovered from the turkey flocks (overall prevalences of 52 and 35%, respectively). Prevalence among flocks ranged from 31 to 86% for C. jejuni and 0 to 67% for C. coli, and both species were recovered from most flocks. Relative prevalence of C. coli was higher in young birds (brooders), whereas C. jejuni predominated in grow-out birds (P < 0.0001). The prevalence of C. coli in a swine herd was generally not a good predictor for prevalence of this species in the corresponding turkey flock. These findings indicate that even though turkeys and swine grown in proximity to each other were commonly colonized with thermophilic campylobacters, the relative prevalences of C. jejuni and C. coli appear to be host associated.}, number={9}, journal={JOURNAL OF FOOD PROTECTION}, author={Wright, S. L. and Carver, D. K. and Siletzky, R. M. and Romine, S. and Morrow, W. E. M. and Kathariou, S.}, year={2008}, month={Sep}, pages={1791–1796} } @article{d'lima_miller_mandrell_wright_siletzky_carver_kathariou_2007, title={Clonal population structure and specific genotypes of multidrug-resistant Campylobacter coli from turkeys}, volume={73}, ISSN={["0099-2240"]}, DOI={10.1128/AEM.02346-06}, abstractNote={ABSTRACT Commercial turkey flocks in North Carolina have been found to be colonized frequently with Campylobacter coli strains that are resistant to several antimicrobials (tetracycline, streptomycin, erythromycin, kanamycin, and ciprofloxacin/nalidixic acid). Such strains have been designated multidrug resistant (MDR). However, the population structure of MDR C. coli from turkeys remains poorly characterized. In this study, an analysis of multilocus sequence typing (MLST)-based sequence types (STs) of 59 MDR strains from turkeys revealed that the majority of these strains corresponded to one of 14 different STs, with three STs accounting for 41 (69%) of the strains. The major STs were turkey specific, and most (87%) of the strains with these STs were resistant to the entire panel of antibiotics mentioned above. Some (13%) of the strains with these STs were susceptible to just one or two of the antibiotics in this panel. Further subtyping using fla typing and pulsed-field gel electrophoresis with SmaI and KpnI revealed that the major MDR STs corresponded to strains of related but distinct subtypes, providing evidence for genomic diversification within these STs. These findings suggest that MDR strains of C. coli from turkeys have a clonal population structure characterized by the presence of a relatively small number of clonal groups that appear to be disseminated in the turkey production system. In addition, the observed correlation between STs and the MDR profiles of the microbes indicates that MLST-based typing holds potential for source-tracking applications specific to the animal source (turkeys) and the antimicrobial resistance profile (MDR status) of C. coli . }, number={7}, journal={APPLIED AND ENVIRONMENTAL MICROBIOLOGY}, author={D'lima, C. B. and Miller, W. G. and Mandrell, R. E. and Wright, S. L. and Siletzky, R. M. and Carver, D. K. and Kathariou, S.}, year={2007}, month={Apr}, pages={2156–2164} } @article{vishnivetskaya_siletzky_jefferies_tiedje_kathariou_2007, title={Effect of low temperature and culture media on the growth and freeze-thawing tolerance of Exiguobacterium strains}, volume={54}, ISSN={["0011-2240"]}, DOI={10.1016/j.cryobiol.2007.01.008}, abstractNote={Bacteria of the genus Exiguobacterium have been repeatedly isolated from ancient permafrost sediments of the Kolyma lowland of Northeast Eurasia. Here we report that the Siberian permafrost isolates Exiguobacterium sibiricum 255-15, E. sibiricum 7-3, Exiguobacterium undae 190-11 and E. sp. 5138, as well as Exiguobacterium antarcticum DSM 14480, isolated from a microbial mat sample of Lake Fryxell (McMurdo Dry Valleys, Antarctica), were able to grow at temperatures ranging from -6 to 40 degrees C. In comparison to cells grown at 24 degrees C, the cold-grown cells of these strains tended to be longer and wider. We also investigated the effect of growth conditions (broth or surface growth, and temperature) on cryotolerance of the Exiguobacterium strains. Bacteria grown in broth at 4 degrees C showed markedly greater survival following freeze-thawing treatments (20 repeated cycles) than bacteria grown in broth at 24 degrees C. Surprisingly, significant protection to repeated freeze-thawing was also observed when bacteria were grown on agar at either 4 or 24 degrees C.}, number={2}, journal={CRYOBIOLOGY}, author={Vishnivetskaya, Tatiana A. and Siletzky, Robin and Jefferies, Natalie and Tiedje, James M. and Kathariou, Sophia}, year={2007}, month={Apr}, pages={234–240} } @article{smith_reimers_barnes_lee_siletzky_kathariou_2004, title={Campylobacter colonization of sibling turkey flocks reared under different management conditions}, volume={67}, ISSN={["1944-9097"]}, DOI={10.4315/0362-028X-67.7.1463}, abstractNote={Uncertainty exists concerning the key factors contributing to Campylobacter colonization of poultry, especially the possible role of vertical transmission from breeder hens to young birds. A longitudinal study of Campylobacter colonization was performed in two sibling pairs of turkey flocks (four flocks total). Each pair of sibling flocks shared breeder hen populations and was obtained from the same hatchery. One flock of each pair was grown on a commercial farm, and the other was grown in an instructional demonstration unit (Teaching Animal Unit [TAU]). Flocks were located within a 60-mi (96.8-km) radius. The time of placement, feed formulations, stocking density, and general husbandry were the same for both flocks, and each flock was processed at a commercial processing plant following standard feed withdrawal and transport protocols. Both flocks grown on the commercial farms became colonized with Campylobacter between weeks 2 and 3 and remained colonized until processing. Between 80 and 90% of isolates were Campylobacter coli, and the remainder were Campylobacter jejuni. In contrast, neither C. coli nor C. jejuni were isolated from either of the TAU flocks at any time during the production cycle. None of the fla types of Campylobacter from the breeders that provided poults to one of the commercial flocks matched those from the progeny. These results failed to provide evidence for vertical transmission and indicate that this type of transmission either did not occur or was not sufficient to render the TAU turkey flocks Campylobacter positive. Management practices such as proper litter maintenance, controlled traffic between the TAU farm and other turkey flocks, and other less well-defined aspects of turkey production were likely responsible for the absence of Campylobacter in the TAU flocks before harvest.}, number={7}, journal={JOURNAL OF FOOD PROTECTION}, author={Smith, K and Reimers, N and Barnes, HJ and Lee, BC and Siletzky, R and Kathariou, S}, year={2004}, month={Jul}, pages={1463–1468} }