Last data update: Jan 27, 2025. (Total: 48650 publications since 2009)
Records 1-16 (of 16 Records) |
Query Trace: Hise KB[original query] |
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Antimicrobial resistance in multistate outbreaks of nontyphoidal Salmonella infections linked to animal contact-United States, 2015-2018
Frey E , Stapleton GS , Nichols MC , Gollarza LM , Birhane M , Chen JC , McCullough A , Carleton HA , Trees E , Hise KB , Tolar B , Francois Watkins L . J Clin Microbiol 2023 e0098123 ![]() ![]() Animal contact is an established risk factor for nontyphoidal Salmonella infections and outbreaks. During 2015-2018, the U.S. Centers for Disease Control and Prevention (CDC) and other U.S. public health laboratories began implementing whole-genome sequencing (WGS) of Salmonella isolates. WGS was used to supplement the traditional methods of pulsed-field gel electrophoresis for isolate subtyping, outbreak detection, and antimicrobial susceptibility testing (AST) for the detection of resistance. We characterized the epidemiology and antimicrobial resistance (AMR) of multistate salmonellosis outbreaks linked to animal contact during this time period. An isolate was considered resistant if AST yielded a resistant (or intermediate, for ciprofloxacin) interpretation to any antimicrobial tested by the CDC or if WGS showed a resistance determinant in its genome for one of these agents. We identified 31 outbreaks linked to contact with poultry (n = 23), reptiles (n = 6), dairy calves (n = 1), and guinea pigs (n = 1). Of the 26 outbreaks with resistance data available, we identified antimicrobial resistance in at least one isolate from 20 outbreaks (77%). Of 1,309 isolates with resistance information, 247 (19%) were resistant to ≥1 antimicrobial, and 134 (10%) were multidrug-resistant to antimicrobials from ≥3 antimicrobial classes. The use of resistance data predicted from WGS increased the number of isolates with resistance information available fivefold compared with AST, and 28 of 43 total resistance patterns were identified exclusively by WGS; concordance was high (>99%) for resistance determined by AST and WGS. The use of predicted resistance from WGS enhanced the characterization of the resistance profiles of outbreaks linked to animal contact by providing resistance information for more isolates. |
Evaluation of whole and core genome multilocus sequence typing allele schemes for Salmonella enterica outbreak detection in a national surveillance network, PulseNet USA
Leeper MM , Tolar BM , Griswold T , Vidyaprakash E , Hise KB , Williams GM , Im SB , Chen JC , Pouseele H , Carleton HA . Front Microbiol 2023 14 1254777 ![]() ![]() Salmonella enterica is a leading cause of bacterial foodborne and zoonotic illnesses in the United States. For this study, we applied four different whole genome sequencing (WGS)-based subtyping methods: high quality single-nucleotide polymorphism (hqSNP) analysis, whole genome multilocus sequence typing using either all loci [wgMLST (all loci)] and only chromosome-associated loci [wgMLST (chrom)], and core genome multilocus sequence typing (cgMLST) to a dataset of isolate sequences from 9 well-characterized Salmonella outbreaks. For each outbreak, we evaluated the genomic and epidemiologic concordance between hqSNP and allele-based methods. We first compared pairwise genomic differences using all four methods. We observed discrepancies in allele difference ranges when using wgMLST (all loci), likely caused by inflated genetic variation due to loci found on plasmids and/or other mobile genetic elements in the accessory genome. Therefore, we excluded wgMLST (all loci) results from any further comparisons in the study. Then, we created linear regression models and phylogenetic tanglegrams using the remaining three methods. K-means analysis using the silhouette method was applied to compare the ability of the three methods to partition outbreak and sporadic isolate sequences. Our results showed that pairwise hqSNP differences had high concordance with cgMLST and wgMLST (chrom) allele differences. The slopes of the regressions for hqSNP vs. allele pairwise differences were 0.58 (cgMLST) and 0.74 [wgMLST (chrom)], and the slope of the regression was 0.77 for cgMLST vs. wgMLST (chrom) pairwise differences. Tanglegrams showed high clustering concordance between methods using two statistical measures, the Baker's gamma index (BGI) and cophenetic correlation coefficient (CCC), where 9/9 (100%) of outbreaks yielded BGI values ≥ 0.60 and CCCs were ≥ 0.97 across all nine outbreaks and all three methods. K-means analysis showed separation of outbreak and sporadic isolate groups with average silhouette widths ≥ 0.87 for outbreak groups and ≥ 0.16 for sporadic groups. This study demonstrates that Salmonella isolates clustered in concordance with epidemiologic data using three WGS-based subtyping methods and supports using cgMLST as the primary method for national surveillance of Salmonella outbreak clusters. |
Multistate outbreak of salmonella thompson infections linked to seafood exposure - United States, 2021
Shen AQ , Dalen A , Bankers L , Matzinger SR , Schwensohn C , Patel K , Hise KB , Pereira E , Cripe J , Jervis RH . MMWR Morb Mortal Wkly Rep 2023 72 (19) 513-516 ![]() ![]() In July 2021, the Colorado Department of Public Health and Environment (CDPHE) laboratory identified a cluster of five Salmonella enterica serotype Thompson isolates related to one another within one allele difference, using whole genome multilocus sequence typing (wgMLST). These five isolates, submitted to the public health laboratory as is routine process for confirmatory testing of Salmonella, were highly related to those identified in a 2020 multistate investigation, during which traceback was conducted for sushi-grade tuna and salmon; a common supplier was not identified. The 2021 investigation commenced on August 5, 2021, with five patients living in Colorado, and one each in Missouri, Washington, and Wisconsin. During August-December 2021, CDC, CDPHE, public health and regulatory officials in several states, and the Food and Drug Administration (FDA) conducted epidemiologic, environmental, and laboratory investigations of this multistate outbreak of Salmonella Thompson. Isolates were genetically related to one another and to 2020 isolates within zero to one allele difference. Implicated seafood products were traced to a single seafood distributor, in which the outbreak strain was identified through environmental sampling, and in which inspection identified inadequate sanitization and opportunities for cross-contamination of raw fish. The distributor issued a voluntary recall of 16 seafood items with high potential for contamination and completed remediation actions. This outbreak illustrated the importance of effective cleaning and sanitizing procedures and implementation of controls. When multiple products are recalled during an outbreak investigation, collaboration between public health agencies and implicated facilities can help provide food safety information to restaurants, retailers, and consumers, and to ensure disposal of all recalled products. |
Evaluation of core genome and whole genome multilocus sequence typing schemes for Campylobacter jejuni and Campylobacter coli outbreak detection in the USA
Joseph LA , Griswold T , Vidyaprakash E , Im SB , Williams GM , Pouseele HA , Hise KB , Carleton HA . Microb Genom 2023 9 (5) ![]() ![]() Campylobacter is a leading causing of bacterial foodborne and zoonotic illnesses in the USA. Pulsed-field gene electrophoresis (PFGE) and 7-gene multilocus sequence typing (MLST) have been historically used to differentiate sporadic from outbreak Campylobacter isolates. Whole genome sequencing (WGS) has been shown to provide superior resolution and concordance with epidemiological data when compared with PFGE and 7-gene MLST during outbreak investigations. In this study, we evaluated epidemiological concordance for high-quality SNP (hqSNP), core genome (cg)MLST and whole genome (wg)MLST to cluster or differentiate outbreak-associated and sporadic Campylobacter jejuni and Campylobacter coli isolates. Phylogenetic hqSNP, cgMLST and wgMLST analyses were also compared using Baker's gamma index (BGI) and cophenetic correlation coefficients. Pairwise distances comparing all three analysis methods were compared using linear regression models. Our results showed that 68/73 sporadic C. jejuni and C. coli isolates were differentiated from outbreak-associated isolates using all three methods. There was a high correlation between cgMLST and wgMLST analyses of the isolates; the BGI, cophenetic correlation coefficient, linear regression model R (2) and Pearson correlation coefficients were >0.90. The correlation was sometimes lower comparing hqSNP analysis to the MLST-based methods; the linear regression model R (2) and Pearson correlation coefficients were between 0.60 and 0.86, and the BGI and cophenetic correlation coefficient were between 0.63 and 0.86 for some outbreak isolates. We demonstrated that C. jejuni and C. coli isolates clustered in concordance with epidemiological data using WGS-based analysis methods. Discrepancies between allele and SNP-based approaches may reflect the differences between how genomic variation (SNPs and indels) are captured between the two methods. Since cgMLST examines allele differences in genes that are common in most isolates being compared, it is well suited to surveillance: searching large genomic databases for similar isolates is easily and efficiently done using allelic profiles. On the other hand, use of an hqSNP approach is much more computer intensive and not scalable to large sets of genomes. If further resolution between potential outbreak isolates is needed, wgMLST or hqSNP analysis can be used. |
Analysis of Salmonella enterica Isolated from a Mixed-Use Watershed in Georgia, USA: Antimicrobial Resistance, Serotype Diversity, and Genetic Relatedness to Human Isolates.
Cho S , Hiott LM , House SL , Woodley TA , McMillan EA , Sharma P , Barrett JB , Adams ES , Brandenburg JM , Hise KB , BatemanMcDonald JM , Ottesen EA , Lipp EK , Jackson CR , Frye JG . Appl Environ Microbiol 2022 88 (10) e0039322 ![]() As the cases of Salmonella enterica infections associated with contaminated water are increasing, this study was conducted to address the role of surface water as a reservoir of S. enterica serotypes. We sampled rivers and streams (n=688) over a 3-year period (2015 to 2017) in a mixed-use watershed in Georgia, USA, and 70.2% of the total stream samples tested positive for Salmonella. A total of 1,190 isolates were recovered and characterized by serotyping, antimicrobial susceptibility testing, and pulsed-field gel electrophoresis (PFGE). A wide range of serotypes was identified, including those commonly associated with humans and animals, with S. enterica serotype Muenchen being predominant (22.7%) and each serotype exhibiting a high degree of strain diversity by PFGE. About half (46.1%) of the isolates had PFGE patterns indistinguishable from those of human clinical isolates in the CDC PulseNet database. A total of 52 isolates (4.4%) were resistant to antimicrobials, out of which 43 isolates were multidrug resistant (MDR; resistance to two or more classes of antimicrobials). These 52 resistant Salmonella isolates were screened for the presence of antimicrobial resistance genes, plasmid replicons, and class 1 integrons, out of which four representative MDR isolates were selected for whole-genome sequencing analysis. The results showed that 28 MDR isolates resistant to 10 antimicrobials had bla(cmy-2) on an A/C plasmid. Persistent contamination of surface water with a high diversity of Salmonella strains, some of which are drug resistant and genetically indistinguishable from human isolates, supports a role of environmental surface water as a reservoir for and transmission route of this pathogen. IMPORTANCE Salmonella has been traditionally considered a foodborne pathogen, as it is one of the most common etiologies of foodborne illnesses worldwide; however, recent Salmonella outbreaks attributed to fresh produce and water suggest a potential environmental source of Salmonella that causes some human illnesses. Here, we investigated the prevalence, diversity, and antimicrobial resistance of Salmonella isolated from a mixed-use watershed in Georgia, USA, in order to enhance the overall understanding of waterborne Salmonella. The persistence and widespread distribution of Salmonella in surface water confirm environmental sources of the pathogen. A high proportion of waterborne Salmonella with clinically significant serotypes and genetic similarity to strains of human origin supports the role of environmental water as a significant reservoir of Salmonella and indicates a potential waterborne transmission of Salmonella to humans. The presence of antimicrobial-resistant and MDR Salmonella demonstrates additional risks associated with exposure to contaminated environmental water. |
Comparison of Molecular Subtyping and Antimicrobial Resistance Detection Methods Used in a Large Multi-State Outbreak of Extensively Drug-Resistant Campylobacter jejuni Infections Linked to Pet Store Puppies.
Joseph LA , Francois Watkins LK , Chen J , Tagg KA , Bennett C , Caidi H , Folster JP , Laughlin ME , Koski L , Silver R , Stevenson L , Robertson S , Pruckler J , Nichols M , Pouseele H , Carleton HA , Basler C , Friedman CR , Geissler A , Hise KB , Aubert RD . J Clin Microbiol 2020 58 (10) ![]() Campylobacter jejuni is a leading cause of enteric bacterial illness in the United States. Traditional molecular subtyping methods, such as pulsed-field gel electrophoresis (PFGE) and 7-gene multilocus sequencing typing (MLST), provided limited resolution to adequately identify C. jejuni outbreaks and separate out sporadic isolates during outbreak investigations. Whole genome sequencing (WGS) has emerged as a powerful tool for C. jejuni outbreak detection. In this investigation, 45 human and 11 puppy isolates obtained during a 2016-2018 outbreak linked to pet store puppies were sequenced. Core genome multilocus sequence typing (cgMLST) and high-quality single nucleotide polymorphism (hqSNP) analysis of the sequence data separated the isolates into the same two clades containing minor within clade differences; however, cgMLST analysis does not require selection of an appropriate reference genome making this method preferable to hqSNP analysis for Campylobacter surveillance and cluster detection. The isolates were classified as ST2109-a rarely seen MLST sequence type. PFGE was performed on 38 human and 10 puppy isolates; PFGE patterns did not reliably predict clustering by cgMLST analysis. Genetic detection of antimicrobial resistance determinants predicted that all outbreak-associated isolates would be resistant to six drug classes. Traditional antimicrobial susceptibility testing (AST) confirmed a high correlation between genotypic and phenotypic antimicrobial resistance determinations. WGS analysis linked C. jejuni isolates in humans and pet store puppies even when canine exposure information was unknown, aiding the epidemiological investigation during this outbreak. WGS data were also used to quickly identify the highly drug-resistant profile of these outbreak-associated C. jejuni isolates. |
Analysis of Escherichia coli and Listeria monocytogenes Isolate subtyping and reporting capacity by public health laboratories, United States (2013-2017)
Martinez D , LeBlanc TT , Hise KB . J Public Health Manag Pract 2019 26 (6) 581-584 OBJECTIVES: To demonstrate the performance of 53 laboratories required to submit 90% or more of their pulsed-field gel electrophoresis (PFGE) subtyping results for Escherichia coli O157:H7 (E coli O157:H7) and Listeria monocytogenes (L monocytogenes) to the PulseNet national databases at the Centers for Disease Control and Prevention (CDC) within 4 working days of receiving isolates. METHODS: We examined data from 53 laboratories during 2013-2017 to ascertain whether E. coli O157:H7 and L monocytogenes PFGE data were reported to the PulseNet national databases within 4 working days. RESULTS: In the study period, 45 laboratories that submitted reports during the period (86.8%) met the target for timely submission of 10 606 (94.85%) E coli O157:H7 isolates into the PulseNet national database. For L monocytogenes isolates, 32 laboratories submitted reports (76.95%) that achieved timely submission of 3119 (93.35%) isolates. CONCLUSIONS: This study uncovered areas for improvement to advance public health in the CDC-funded laboratories. |
PulseNet: Entering the Age of Next-Generation Sequencing.
Ribot EM , Freeman M , Hise KB , Gerner-Smidt P . Foodborne Pathog Dis 2019 16 (7) 451-456 ![]() ![]() Since 1996, PulseNet has served as the national laboratory-based surveillance system for the rapid detection of outbreaks caused by foodborne bacterial pathogens in the United States. For the past two decades, pulsed-field gel electrophoresis was the gold standard subtyping method for the pathogens tracked by PulseNet. A new gold standard is now being implemented with the introduction of cost-effective whole genome sequencing (WGS) for analysis of all the organisms tracked by PulseNet. This transformation is a major undertaking that touches every functional aspect of PulseNet, including laboratory workflows, data storage, analysis management and data interpretation, and language used to communicate information (sequence profile nomenclature system). The benefits of implementing WGS go beyond improved discrimination and precision of the data; it provides an opportunity to determine strain characteristics typically obtained through resource-intensive traditional methodologies, for example, species identification, serotyping, virulence, and antimicrobial resistance profiling, all of which can be consolidated into a single WGS workflow. Such a strategy represents a major shift in the workflows currently practiced in most public health laboratories, but one that brings opportunities for streamlining surveillance activities for the network as a whole. In this study, we provide a brief summary of PulseNet's evolution the past decade along with a general description of the challenges and opportunities that lie ahead. |
An Overview of PulseNet USA Databases.
Tolar B , Joseph LA , Schroeder MN , Stroika S , Ribot EM , Hise KB , Gerner-Smidt P . Foodborne Pathog Dis 2019 16 (7) 457-462 ![]() ![]() PulseNet USA is the molecular surveillance network for foodborne disease in the United States. The network consists of state and local public health laboratories, as well as food regulatory agencies, that follow PulseNet's standardized protocols to perform pulsed-field gel electrophoresis (PFGE) and whole genome sequencing (WGS) and analyze the results using standardized software. The raw sequences are uploaded to the GenomeTrakr or PulseNet bioprojects at the National Center for Biotechnology Information. The PFGE patterns and analyzed sequence data are uploaded in real time with associated demographic data to the PulseNet national databases managed at the Centers for Disease Control and Prevention. The PulseNet databases are organism specific and provide a central storage location for molecular and demographic data related to an isolate. Sequences are compared in the databases, thereby facilitating the rapid detection of clusters of foodborne diseases that may represent widespread outbreaks. WGS genotyping data, for example, antibiotic resistance and virulence profiles, are also uploaded in real time to the PulseNet databases to improve food safety surveillance activities. |
Notes from the Field: Environmental Investigation of a Multistate Salmonellosis Outbreak Linked to Live Backyard Poultry from a Mail-Order Hatchery - Michigan, 2018.
Hardy MC , Robertson SA , Sidge J , Signs K , Stobierski MG , Jones K , Soehnlen M , Stefanovsky L , Hambley A , Brandenburg JM , Martin H , Lauer AC , Fields P , Koski L , Stevenson LM , Pabilonia KL , Nichols MC , Basler CA , Ribot EM , Hise KB . MMWR Morb Mortal Wkly Rep 2019 67 (5152) 1430-1431 ![]() ![]() In the United States, contact with live poultry has been linked to 70 Salmonella outbreaks resulting in 4,794 clinical cases since 2000 (1). Environmental sampling to confirm the outbreak strain at poultry hatcheries that supply backyard flocks is conducted infrequently during investigations; therefore, the source of the outbreak is rarely identified. On June 12, 2018, the Michigan Department of Health and Human Services requested assistance from CDC to investigate risk factors for Salmonella infection linked to live backyard poultry originating at a mail-order hatchery in Michigan (hatchery A). This hatchery supplies young poultry (poults) to backyard flocks through direct sale to flock owners and via feed stores. At the start of the investigation, traceback had linked 24 clinical cases of Salmonella enterica serotype Enteritidis to exposure to live poultry from hatchery A. Whole genome sequencing analysis of the clinical isolates revealed that they were closely related (within 0–15 alleles) by whole genome multilocus sequence typing to environmental isolates sampled from shipping containers originating from hatchery A at retail outlets in several states. |
Protracted Outbreak of Salmonella Newport Infections Linked to Ground Beef: Possible Role of Dairy Cows - 21 States, 2016-2017.
Marshall KEH , Tewell M , Tecle S , Leeper M , Sinatra J , Kissler B , Fung A , Brown K , Wagner D , Trees E , Hise KB , Chaturvedi V , Schlater LK , Morningstar-Shaw BR , Whitlock L , Holt K , Becker K , Nichols M , Williams IT , Jhung M , Wise ME , Gieraltowski L . MMWR Morb Mortal Wkly Rep 2018 67 (15) 443-446 ![]() ![]() In January 2017, CDC identified a cluster of Salmonella enterica serotype Newport infections with isolates sharing an indistinguishable pulsed-field gel electrophoresis (PFGE) pattern, JJPX01.0010 (pattern 10), through PulseNet, the national molecular subtyping network for foodborne disease surveillance. This report summarizes the investigation by CDC, state and local health and agriculture departments, and the U.S. Department of Agriculture's Food Safety and Inspection Service (USDA-FSIS) and discusses the possible role of dairy cows as a reservoir for strains of Salmonella that persistently cause human illness. This investigation combined epidemiologic and whole genome sequencing (WGS) data to link the outbreak to contaminated ground beef; dairy cows were hypothesized to be the ultimate source of Salmonella contamination. |
Urbanized white ibises (Eudocimus albus) as carriers of Salmonella enterica of significance to public health and wildlife
Hernandez SM , Welch CN , Peters VE , Lipp EK , Curry S , Yabsley MJ , Sanchez S , Presotto A , Gerner-Smidt P , Hise KB , Hammond E , Kistler WM , Madden M , Conway AL , Kwan T , Maurer JJ . PLoS One 2016 11 (10) e0164402 Worldwide, Salmonella spp. is a significant cause of disease for both humans and wildlife, with wild birds adapted to urban environments having different opportunities for pathogen exposure, infection, and transmission compared to their natural conspecifics. Food provisioning by people may influence these factors, especially when high-density mixed species flocks aggregate. White Ibises (Eudocimus albus), an iconic Everglades species in decline in Florida, are becoming increasingly common in urbanized areas of south Florida where most are hand-fed. We examined the prevalence of Salmonella shedding by ibises to determine the role of landscape characteristics where ibis forage and their behavior, on shedding rates. We also compared Salmonella isolated from ibises to human isolates to better understand non-foodborne human salmonellosis. From 2010-2013, 13% (n = 261) adult/subadult ibises and 35% (n = 72) nestlings sampled were shedding Salmonella. The prevalence of Salmonella shedding by ibises significantly decreased as the percent of Palustrine emergent wetlands and herbaceous grasslands increased, and increased as the proportion of open-developed land types (e.g. parks, lawns, golf courses) increased, suggesting that natural ecosystem land cover types supported birds with a lower prevalence of infection. A high diversity of Salmonella serotypes (n = 24) and strain types (43 PFGE types) were shed by ibises, of which 33% of the serotypes ranked in the top 20 of high significance for people in the years of the study. Importantly, 44% of the Salmonella Pulsed-Field Gel Electrophoresis patterns for ibis isolates (n = 43) matched profiles in the CDC PulseNet USA database. Of these, 20% came from Florida in the same three years we sampled ibis. Importantly, there was a negative relationship between the amount of Palustrine emergent wetland and the number of Salmonella isolates from ibises that matched human cases in the PulseNet database (p = 0.056). Together, our results indicate that ibises are good indicators of salmonellae strains circulating in their environment and they have both the potential and opportunity to transmit salmonellae to people. Finally, they may act as salmonellae carriers to natural environments where other more highly-susceptible groups (nestlings) may be detrimentally affected. |
Future challenges for tracking foodborne diseases: PulseNet, a 20-year-old US surveillance system for foodborne diseases, is expanding both globally and technologically
Ribot EM , Hise KB . EMBO Rep 2016 17 (11) 1499-1505 After 20 years of successfully tracking and preventing outbreaks of foodborne diseases, PulseNet, a US surveillance program, is implementing new diagnostic technologies and expanding its international cooperation with public health agencies. [Image: see text] |
Diversity and persistence of Salmonella enterica strains in rural landscapes in the southeastern United States
Maurer JJ , Martin G , Hernandez S , Cheng Y , Gerner-Smidt P , Hise KB , Tobin D'Angelo M , Cole D , Sanchez S , Madden M , Valeika S , Presotto A , Lipp EK . PLoS One 2015 10 (7) e0128937 Salmonellosis cases in the in the United States show distinct geographical trends, with the southeast reporting among the highest rates of illness. In the state of Georgia, USA, non-outbreak associated salmonellosis is especially high in the southern low-lying coastal plain. Here we examined the distribution of Salmonella enterica in environmental waters and associated wildlife in two distinct watersheds, one in the Atlantic Coastal Plain (a high case rate rural area) physiographic province and one in the Piedmont (a lower case rate rural area). Salmonella were isolated from the two regions and compared for serovar and strain diversity, as well as distribution, between the two study areas, using both a retrospective and prospective design. Thirty-seven unique serovars and 204 unique strain types were identified by pulsed-field gel electrophoresis (PFGE). Salmonella serovars Braenderup, Give, Hartford, and Muenchen were dominant in both watersheds. Two serovars, specifically S. Muenchen and S. Rubislaw, were consistently isolated from both systems, including water and small mammals. Conversely, 24 serovars tended to be site-specific (64.8%, n = 37). Compared to the other Salmonella serovars isolated from these sites, S. Muenchen and S. Rubislaw exhibited significant genetic diversity. Among a subset of PFGE patterns, approximately half of the environmental strain types matched entries in the USA PulseNet database of human cases. Ninety percent of S. Muenchen strains from the Little River basin (the high case rate area) matched PFGE entries in PulseNet compared to 33.33% of S. Muenchen strains from the North Oconee River region (the lower case rate area). Underlying the diversity and turnover of Salmonella strains observed for these two watersheds is the persistence of specific Salmonella serovars and strain types that may be adapted to these watersheds and landscapes. |
Meta-analysis of pulsed-field gel electrophoresis fingerprints based on a constructed Salmonella database
Zou W , Chen HC , Hise KB , Tang HL , Foley SL , Meehan J , Lin WJ , Nayak R , Xu JS , Fang H , Chen JJ . PLoS One 2013 8 (3) e59224 A database was constructed consisting of 45,923 Salmonella pulsed-field gel electrophoresis (PFGE) patterns. The patterns, randomly selected from all submissions to CDC PulseNet during 2005 to 2010, included the 20 most frequent serotypes and 12 less frequent serotypes. Meta-analysis was applied to all of the PFGE patterns in the database. In the range of 20 to 1100 kb, serotype Enteritidis averaged the fewest bands at 12 bands and Paratyphi A the most with 19, with most serotypes in the 13-15 range among the 32 serotypes. The 10 most frequent bands for each of the 32 serotypes were sorted and distinguished, and the results were in concordance with those from distance matrix and two-way hierarchical cluster analyses of the patterns in the database. The hierarchical cluster analysis divided the 32 serotypes into three major groups according to dissimilarity measures, and revealed for the first time the similarities among the PFGE patterns of serotype Saintpaul to serotypes Typhimurium, Typhimurium var. 5-, and I 4,[5], 12:i:-; of serotype Hadar to serotype Infantis; and of serotype Muenchen to serotype Newport. The results of the meta-analysis indicated that the pattern similarities/dissimilarities determined the serotype discrimination of PFGE method, and that the possible PFGE markers may have utility for serotype identification. The presence of distinct, serotype specific patterns may provide useful information to aid in the distribution of serotypes in the population and potentially reduce the need for laborious analyses, such as traditional serotyping. |
Prediction system for rapid identification of salmonella serotypes based on pulsed-field gel electrophoresis fingerprints
Zou W , Lin WJ , Hise KB , Chen HC , Keys C , Chen JJ . J Clin Microbiol 2012 50 (5) 1524-32 ![]() ![]() A classification model is presented for rapid identification of Salmonella serotypes based on pulsed-field gel electrophoresis (PFGE) fingerprints. The classification model was developed using random forest and support vector machine algorithms and was then applied to a database of 45,923 PFGE patterns, randomly selected from all submissions to CDC PulseNet from 2005 to 2010. The patterns selected included the top 20 most frequent serotypes and 12 less frequent serotypes from various sources. The prediction accuracies for the 32 serotypes ranged from 68.8% to 99.9%, with an overall accuracy of 96.0% for the random forest classification, and ranged from 67.8% to 100.0%, with an overall accuracy of 96.1% for the support vector machine classification. The prediction system improves reliability and accuracy and provides a new tool for early and fast screening and source tracking of outbreak isolates. It is especially useful to get serotype information before the conventional methods are done. Additionally, this system also works well for isolates that are serotyped as "unknown" by conventional methods, and it is useful for a laboratory where standard serotyping is not available. |
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