Poly(indole-5-carboxylic acid)/reduced graphene oxide/gold nanoparticles/phage-based electrochemical biosensor for highly specific detection of Yersinia pseudotuberculosis.

Yersinia pseudotuberculosis is an enteric bacterium causing yersiniosis in humans. The existing Yersinia pseudotuberculosis detection methods are time-consuming, requiring a sample pretreatment step, and are unable to discriminate live/dead cells. The current work reports a phage-based electrochemical biosensor for rapid and specific detection of Yersinia pseudotuberculosis. The conductive poly(indole-5-carboxylic acid), reduced graphene oxide, and gold nanoparticles are applied for surface modification of the electrode. They possess ultra-high redox stability and retain 97.7% of current response after performing 50 consecutive cycles of cyclic voltammetry.The specific bacteriophages vB_YepM_ZN18 we isolated from hospital sewage water were immobilized on modified electrodes by Au-NH2 bond between gold nanoparticles and phages. The biosensor fabricated with nanomaterials and phages were utilized to detect Yersinia pseudotuberculosis successfully with detection range of 5.30 × 102 to 1.05 × 107 CFU mL-1, detection limit of 3 CFU mL-1, and assay time of 35 min. Moreover, the biosensor can specifically detect live Yersinia pseudotuberculosis without responding to phage-non-host bacteria and dead Yersinia pseudotuberculosis cells. These results suggest that the proposed biosensor is a promising tool for the rapid and selective detection of Yersinia pseudotuberculosis in food, water, and clinical samples.

Modeling of Interspecific Interaction of Yersinia pseudotuberculosis and Listeria monocytogenes in a Mixed-Species Biofilms with Microorganisms Isolated from Coastal Waters of the Sea of Japan.

We studied the possibility of formation of mixed-species biofilms by Yersinia pseudotuberculosis and Listeria monocytogenes with marine saprotrophic bacteria Flavobacterium sp. and Micrococcus luteus isolated from the coastal waters of the Sea of Japan in summer. Model experiments showed that Flavobacterium sp. and Micrococcus luteus can form both single- and mixed-species biofilms with the specified pathogenic bacteria thus stimulating their growth. This can contribute to the preservation of the pathogens in the marine environment.

Yersinia pseudotuberculosis serotype O:1 infection in a captive Seba's short tailed-fruit bat (Carollia perspicillata) colony in Switzerland.

BACKGROUND: Between February and April 2016, a slight increase in mortality was observed in a colony consisting of 400 captive Seba's short-tailed bats (Carollia perspicillata). These animals cohabited with other nocturnal animal species in a dome of a private zoo in Switzerland. RESULTS: Gross and histological analysis of two (14.3%) out of the 13 animals submitted for necropsy within this period revealed a necrosuppurative pneumonia, hepatitis, splenitis, enterocolitis, and endometritis, with abundant intralesional colonies of Gram-negative rods. Yersinia (Y.) pseudotuberculosis serotype O:1 and biotype 1 belonging to the sequence type ST90 was isolated from the affected organs in both animals. Following this diagnosis, » of the colony (99 animals) was culled and submitted for gross and histopathological analysis, and a bacterial culture selective for Yersinia spp. of lung, liver, and spleen was performed. From these 99 animals, one gravid female was tested and found to be positive for Y. pseudotuberculosis in the absence of clinical symptoms and histopathological lesions. PCR analysis of altogether three bacterial isolates for virulence factors revealed the presence of the ail gene, and one isolate was also positive for the virF and yadA plasmid genes. CONCLUSIONS: These findings suggest that Carollia perspicillata are susceptible to lethal yersiniosis but do not represent a regular reservoir for Y. pseudotuberculosis. Culling of » of the population was sufficient to limit the spread of this infection among the colony. Moreover, no infections were detected in cohabitant nocturnal animals and caretakers, indicating that the zoonotic risk in this case was low.

Septic shock due to Yersinia pseudotuberculosis infection in an adult immunocompetent patient: a case report and literature review.

BACKGROUND: Yersinia pseudotuberculosis infection can occur in an immunocompromised host. Although rare, bacteremia due to Y. pseudotuberculosis may also occur in immunocompetent hosts. The prognosis and therapeutic strategy, especially for immunocompetent patients with Y. pseudotuberculosis bacteremia, however, remains unknown. CASE PRESENTATION: A 38-year-old Japanese man with a mood disorder presented to our hospital with fever and diarrhea. Chest computed tomography revealed consolidation in the right upper lobe with air bronchograms. He was diagnosed with pneumonia, and treatment with intravenous ceftriaxone and azithromycin was initiated. The ceftriaxone was replaced with doripenem and the azithromycin was discontinued following the detection of Gram-negative rod bacteria in 2 sets of blood culture tests. The isolated Gram-negative rod bacteria were confirmed to be Y. pseudotuberculosis. Thereafter, he developed septic shock. Doripenem was switched to cefmetazole, which was continued for 14 days. He recovered without relapse. CONCLUSIONS: We herein report a case of septic shock due to Y. pseudotuberculosis infection in an adult immunocompetent patient. The appropriate microorganism tests and antibiotic therapy are necessary to treat patients with Y. pseudotuberculosis bacteremia.

Pentaplex real-time PCR for differential detection of Yersinia pestis and Y. pseudotuberculosis and application for testing fleas collected during plague epizootics.

Upon acquiring two unique plasmids (pMT1 and pPCP1) and genome rearrangement during the evolution from Yersinia pseudotuberculosis, the plague causative agent Y. pestis is closely related to Y. pseudotuberculosis genetically but became highly virulent. We developed a pentaplex real-time PCR assay that not only detects both Yersinia species but also differentiates Y. pestis strains regarding their plasmid profiles. The five targets used were Y. pestis-specific ypo2088, caf1, and pst located on the chromosome, plasmids pMT1 and pPCP1, respectively; Y. pseudotuberculosis-specific chromosomal gene opgG; and 18S ribosomal RNA gene as an internal control for flea DNA. All targets showed 100% specificity and high sensitivity with limits of detection ranging from 1 fg to 100 fg, with Y. pestis-specific pst as the most sensitive target. Using the assay, Y. pestis strains were differentiated 100% by their known plasmid profiles. Testing Y. pestis and Y. pseudotuberculosis-spiked flea DNA showed there is no interference from flea DNA on the amplification of targeted genes. Finally, we applied the assay for testing 102 fleas collected from prairie dog burrows where prairie dog die-off was reported months before flea collection. All flea DNA was amplified by 18S rRNA; no Y. pseudotuberculosis was detected; one flea was positive for all Y. pestis-specific targets, confirming local Y. pestis transmission. Our results indicated the assay is sensitive and specific for the detection and differentiation of Y. pestis and Y. pseudotuberculosis. The assay can be used in field investigations for the rapid identification of the plague causative agent.

Unilateral inguinal lymphadenitis caused by Yersinia pseudotuberculosis. A case report.

Acute inguinal lymphadenitis is usually caused by lower extremity infection and sexually transmitted diseases, such as chancroid, lymphogranuloma venereum, genital herpes, or syphilis. Yersinia pseudotuberculosis is a non-spore forming, pleomorphic, non-lactose fermenting Gram negative bacillus and a member of the family Enterobacteriaceae, which is associated with diarrheal diseases. It also causes mesenteric lymphadenitis at the terminal ileum, which can be clinically indistinguishable from acute appendicitis (pseudoappendicitis). However, lymphadenitis in other regions caused by the organism is rarely reported. Herein, we report a case of a man in his 20s, who presented with unilateral inguinal lymphadenitis caused by Y. pseudotuberculosis, with discussion regarding the pathogenesis of this rare occurrence.

The Prevalence of Yersinia enterocolitica and Yersinia pseudotuberculosis in Small Wild Rodents in Poland.

Rodents are a large group of mammals that can be carriers of zoonotic pathogens such as Yersinia strains that cause yersiniosis. The prevalence of Yersinia enterocolitica and Yersinia pseudotuberculosis was determined in 214 small wild rodents from south-eastern Poland. Samples were analyzed by precultivation and PCR. Nine (4.2%) Y. enterocolitica and one (0.5%) Y. pseudotuberculosis isolates were received. Most of them (n = 5) were obtained from the common vole (Microtus arvalis). All Y. enterocolitica strains were classified as biotype (BT) 1A. A PCR analysis of virulence markers revealed that all Y. enterocolitica isolates contained the ystB gene and five isolates harbored a rare genetic combination of ail/ystB. Three of the four ail/ystB-positive isolates belonged to serotype O:5.27. The Y. pseudotuberculosis inv-positive isolate was classified as BT 1. A genetic analysis of Y. enterocolitica harboring the ystB gene revealed 100% similarity between the analyzed sequences and the sequences from diarrhea patients in India and the United Kingdom as well as high similarity with the sequences from different species of wild animals from Poland. The Y. pseudotuberculosis inv sequence was 100% identical to the sequence isolated from fully virulent clinical strain from France and Australia. The results of our study suggest that small wild rodents, especially voles and yellow-necked mice, may act as carriers of Yersinia strains. The high similarity of the tested gene sequences between our isolates and the isolates from other free-living animals indicates that small wild rodents can play a role in the epidemiology of yersiniosis and can shed Yersinia spp. into the environment.

A horse and a zebra: an atypical clinical picture including Guillain-Barré syndrome, recurrent fever and mesenteric lymphadenopathy caused by two concomitant infections.

BACKGROUND: While Campylobacter jejuni represents the most common cause of bacterial gastroenteritis, Yersinia pseudotuberculosis infections are very rarely diagnosed in adults. CASE: We report on a previously healthy patient who presented several times at our hospital with fever, Guillain-Barré syndrome, recurrent abdominal symptoms and distinct mesenteric lymphadenopathy, respectively. This complicated and diagnostically challenging course of disease was caused by a C. jejuni and Y. pseudotuberculosis coinfection. Antibiotic treatment with doxycycline was effective. CONCLUSION: Broad serology testing was crucial to discover that two concomitant infections were causing the symptoms. This case demonstrates that when a clinical picture is not fully explained by one known infection, another infection with the same underlying risk factor has to be considered, hence "a horse and a zebra".

YERSINIA PSEUDOTUBERCULOSIS INFECTIONS IN PRIMATES, ARTIODACTYLS, AND BIRDS WITHIN A ZOOLOGICAL FACILITY IN THE UNITED KINGDOM.

Infection with Yersinia pseudotuberculosis can be difficult to diagnose and treat successfully. Twenty-four cases from the Zoological Society of London (ZSL) London Zoo and ZSL Whipsnade Zoo were identified between 2001 and 2019. Husbandry, medical, and postmortem records for six primates, 10 artiodactyls, and eight birds were reviewed to identify common clinical signs and gross lesions. Most cases occurred during the winter; however, an outbreak in four primates occurred during the summer following a period of stress associated with increased ambient noise and activity. Common clinical signs included lethargy (6/6 primates, 4/10 artiodactyls, 4/8 birds) or death without premonitory signs (3/10 artiodactyls, 4/8 birds). Once clinical signs were observed, disease progressed quickly. Poor condition was common in mammals (6/6 primates, 9/10 artiodactyls), but often went undetected until postmortem examination. Neurological signs occurred in three of six primates. Diarrhea and anorexia were uncommon in all animals. Hepatitis was observed in all groups (4/6 primates, 2/10 artiodactyls, 4/8 birds), mesenteric lymphadenomegaly was common in mammals (4/6 primates, 8/10 artiodactyls), and gastroenteritis was common in artiodactyls (7/10). Erythematous, punctate rashes, which have only been reported with yersiniosis in humans, were present in three of six primates. Bacterial cultures from the liver in primates and birds or enlarged mesenteric lymph nodes in artiodactyls were often diagnostic. All isolates were susceptible to marbofloxacin, oxytetracycline, streptomycin, ceftazidime, amoxicillin clavulanic acid, trimethoprim sulfamethoxazole, azithromycin, and doxycycline, and resistant to clindamycin. Histopathology and Perl's Prussian blue stains were performed on available liver samples (n = 18). Intracellular hemosiderin was present in 17 of 18 cases. Additional research is needed to determine if there is a relationship between hemosiderosis and yersiniosis.

The design, validation and clinical verification of an in-house qualitative PCR to detect Yersinia enterocolitica and Yersinia pseudotuberculosis in faeces.

Yersiniosis is a zoonotic foodborne infection of public health significance. The aim of this study was to design and validate a simple, accurate and cost-effective polymerase chain reaction (PCR) to detect pathogenic Yersinia spp. in faecal samples. An intercalating dye (EvaGreen)-based real-time multiplex PCR assay was designed to detect yadA, ystB and inv by melt curve analysis, allowing undifferentiated detection of all Yersinia enterocolitica biotypes, including biotype 1A, and Yersinia pseudotuberculosis. The assay was validated using cultured bacteria and clinical samples. A total of 107 positive and 51 negative samples were tested. The sensitivity and specificity was 98% and 100%. The limit of detection was 104-105 CFU/g faeces. A total of 605 samples (9 positive) were tested in the clinical verification with an accuracy and negative predictive value of 99% [95% confidence interval (CI) 97.9-99.6%] and 99.8% (95% CI 97.9-99.6%), respectively. This is an accurate, simple and cost-effective assay for the detection of pathogenic Yersinia spp.

Automated multi-sample acquisition and analysis using atomic force microscopy for biomedical applications.

In the last 20 years, atomic force microscopy (AFM) has emerged as a ubiquitous technique in biological research, allowing the analysis of biological samples under near-physiological conditions from single molecules to living cells. Despite its growing use, the low process throughput remains a major drawback. Here, we propose a solution validated on a device allowing a fully automated, multi-sample analysis. Our approach is mainly designed to study samples in fluid and biological cells. As a proof of concept, we demonstrate its feasibility applied to detect and scan both fixed and living bacteria before completion of data processing. The effect of two distinct treatments (i.e. gentamicin and heating) is then evidenced on physical parameters of fixed Yersinia pseudotuberculosis bacteria. The multi-sample analysis presented allows an increase in the number of scanned samples while limiting the user's input. Importantly, cantilever cleaning and control steps are performed regularly-as part of the automated process-to ensure consistent scanning quality. We discuss how such an approach is paving the way to AFM developments in medical and clinical fields, in which statistical significance of results is a prerequisite.

Identification and typing of Yersinia enterocolitica and Yersinia pseudotuberculosis isolated from human clinical specimens in England between 2004 and 2018.

PurposeandMethodology. Epidemiological and microbiological data on Yersinia enterocolitica (n=699) and Yersinia pseudotuberculosis (n=35) isolated from human clinical specimens in England between April 2004 and March 2018 were reviewed. Traditional biochemical species identification and serological typing results were compared with species identifications and serotypes derived from whole-genome sequencing (WGS) data for a sub-set of these isolates (n=179).Results. Most Y. enterocolitica isolates were from faecal specimens (74.4%) from adults (80.7%) and 50.7  % of isolates were from male patients. Most Y. pseudotuberculosis isolates were from blood cultures (68.6%) from adults (91%) and 60.0  % of isolates were from male patients. All sequenced isolates of Y. enterocolitica (n=158) and Y. pseudotuberculosis (n=21), as well as isolates belonging to other Yersinia species (n=21), were correctly identified from genomic data using a kmer-based identification approach. Traditional phenotypic serotyping typed 82/158 and 12/21 isolates of Y. enterocolitica and Y. pseudotuberculosis, respectively, while 118/158 and 21/21 isolates of Y. enterocolitica and Y. pseudotuberculosis, respectively, were typed by the genome-derived serotyping method. In addition, WGS data provided a multi-locus sequence type profile and virulence gene profile for all isolates.Conclusion. The use of WGS for typing Y. enterocolitica and Y. pseudotuberculosis at Public Health England will facilitate the monitoring of animal-to-human transmission of these important foodborne pathogens in the UK and improve public health surveillance of the pathogenic lineages.

LAMP-based assay can rectify the diagnosis of Yersinia pseudotuberculosis infections otherwise missed by serology.

BACKGROUND: Despite being a well-known but seldom encountered zoonotic pathogen, diagnosis of Yersinia pseudotuberculosis is not necessarily easy. Infected patients occasionally present with various symptoms resembling Kawasaki disease; thus discriminating the two in the acute phase is challenging. In addition to bacterial culture and serology, novel detection methods based on loop-mediated isothermal amplification (LAMP) are reported in the literature. However, the clinical utility of LAMP-based methods in comparison with the other methods is scarcely documented in the literature. AIM: To clarify the clinical utility of a LAMP-based method in the diagnosis of Yersinia pseudotuberculosis infection. METHODOLOGY: Inpatients admitted due to suspected Yersinia pseudotuberculosis infection during April 2008 through March 2015 were enrolled. Results of the LAMP-based method as well as culture and serology were collected and compared. RESULTS: Among 16 eligible cases, serology proved positive in 13 (81.3 %) cases, LAMP in eight (50 %) cases, and bacterial culture in four (25 %) cases. No significant difference among the three methods could be proved statistically. Although serology was the most sensitive method, it is known to miss cases such as young patients, whereas LAMP could complement all three cases missed by serology. Furthermore, LAMP can return the test result within a few hours from specimen receipt, whereas serology and bacterial culture requires days to weeks of time. CONCLUSION: Although second to serology in sensitivity, the LAMP-based method proved its utility in making rapid diagnosis, and serving a complementary role to serology.

Yersiniosis in Poland in 2017

AIM: The aim of the study is to assess epidemiological situation of yersiniosis in Poland in 2017 in comparison to previous years. MATERIAL AND METHODS: The evaluation is based on analysis of data from the annual bulletins "Infectious diseases and poisoning in Poland", information from individual yersiniosis case reports entered and shared by local sanitary-epidemiological stations through Electronic Registry of Epidemiologic Forms (SRWE), information from individual extraintestinal case reports fulfilled by local sanitary-epidemiological station and sent to the Departments of Epidemiology, National Institute of Public Health - National Institute of Hygiene by regional sanitary-epidemiological stations, information on outbreaks shared through the Electronic Registry of Epidemic Outbreaks (ROE) and data on deaths from the Department of Demographic Studies of the Central Statistical Office. RESULTS: In 2017 255 cases of yersiniosis, including 191 intestinal and 64 extraintestinal were registered. Incidence in 2017 was 0.66/100 000 population. Number of cases registered in 2017 was higher than in 2015 and 2016 (for both years 205 cases with incidence 0.53/100 000 was observed) and similar to the one in 2014 (244 cases, incidence 0.63/100 000). In 2017 all intestinal yersiniosis cases met criteria for confirmed case. Around 35% of cases were registered in mazowieckie voivodship where incidence was similar to the one in European Union. Among Y. enterocolitica isolates, serotype was determined in 62 cases what stands for only 28.7% of all cases. Predominant serotype was 03, it was identified in 81% of serotyped cases. Most of intestinal yersiniosis cases occurred among children under 4 years (54.5% of all registered cases). CONCLUSIONS: In 2017 increase in number of cases was observed. Yersiniosis in Poland is rarely diagnosed, incidence in Poland is more than twice time lower than in European Union.

Changes in Transcriptome of Yersinia pseudotuberculosis IP32953 Grown at 3 and 28°C Detected by RNA Sequencing Shed Light on Cold Adaptation.

Yersinia pseudotuberculosis is a bacterium that not only survives, but also thrives, proliferates, and remains infective at cold-storage temperatures, making it an adept foodborne pathogen. We analyzed the differences in gene expression between Y. pseudotuberculosis IP32953 grown at 3 and 28°C to investigate which genes were significantly more expressed at low temperature at different phases of growth. We isolated and sequenced the RNA from six distinct corresponding growth points at both temperatures to also outline the expression patterns of the differentially expressed genes. Genes involved in motility, chemotaxis, phosphotransferase systems (PTS), and ATP-binding cassette (ABC) transporters of different nutrients such as fructose and mannose showed higher levels of transcripts at 3°C. At the beginning of growth, especially genes involved in securing nutrients, glycolysis, transcription, and translation were upregulated at 3°C. To thrive as well as it does at low temperature, Y. pseudotuberculosis seems to require certain cold shock proteins, especially those encoded by yptb3585, yptb3586, yptb2414, yptb2950, and yptb1423, and transcription factors, like Rho, IF-1, and RbfA, to maintain its protein synthesis. We also found that genes encoding RNA-helicases CsdA (yptb0468), RhlE (yptb1214), and DbpA (yptb1652), which unwind frozen secondary structures of nucleic acids with cold shock proteins, were significantly more expressed at 3°C, indicating that these RNA-helicases are important or even necessary during cold. Genes involved in excreting poisonous spermidine and acquiring compatible solute glycine betaine, by either uptake or biosynthesis, showed higher levels of transcripts at low temperatures. This is the first finding of a strong connection between the aforementioned genes and the cold adaptation of Y. pseudotuberculosis. Understanding the mechanisms behind the cold adaptation of Y. pseudotuberculosis is crucial for controlling its growth during cold storage of food, and will also shed light on microbial cold adaptation in general.

Novel diagnostic ELISA test for discrimination between infections with Yersinia enterocolitica and Yersinia pseudotuberculosis.

Yersiniosis is a foodborne infection caused by Yersinia enterocolitica or Yersinia pseudotuberculosis. Although yersiniosis is most often self-limiting, some patients develop chronic infections, such as reactive arthritis, glomerulonephritis, or myocarditis, which require an antibiotic treatment. Whereas early infections can be diagnosed by direct detection of bacteria, chronic infections can only be identified by serological tests. At this point, a serological method for differentiation between infections with the two Yersinia species is important since antibiotic susceptibility of these bacteria is different. Traditional immunoassays do not distinguish between infections with Y. enterocolitica and Y. pseudotuberculosis. The only test that allows for this differentiation is Mikrogen's strip test where discrimination between the two types of infection is based on two recombinant bacterial proteins, MyfA and PsaA (specific for Y. enterocolitica and Y. pseudotuberculosis, respectively). Here, we show that Y. enterocolitica and Y. pseudotuberculosis, cultured under the conditions that mimic the natural rout of infection, express surface antigens different from MyfA and PsaA that can also be used in a discrimination test. Further, we describe a new ELISA that is based on the whole bacteria and recombinant MyfA and PsaA as antigens, and that allows the differentiation between infections with Y. enterocolitica and Y. pseudotuberculosis and simultaneous detection of yersiniosis.

Yersinia pseudotuberculosis Prevalence and Diversity in Wild Boars in Northeast Germany.

In this study, the prevalence of Yersinia pseudotuberculosis in wild boars in northeast Germany was determined. For that purpose, the tonsils of 503 wild boars were sampled. The presence of Y. pseudotuberculosis was studied by diagnostic PCR. Positive samples were analyzed by cultural detection using a modified cold enrichment protocol. Ten Y. pseudotuberculosis isolates were obtained, which were characterized by biotyping, molecular serotyping, and multilocus sequence typing (MLST). In addition, whole-genome sequences and the antimicrobial susceptibility of the isolates were analyzed. Yersinia pseudotuberculosis was isolated from male and female animals, most of which were younger than 1 year. A prevalence of 2% (10/503) was determined by cultural detection, while 6.4% (32/503) of the animals were positive by PCR. The isolates belonged to the biotypes 1 and 2 and serotypes O:1a (n = 7), O:1b (n = 2), and O:4a (n = 1). MLST analysis revealed three sequence types, ST9, ST23, and ST42. Except one isolate, all isolates revealed a strong resistance to colistin. The relationship of the isolates was studied by whole-genome sequencing demonstrating that they belonged to four clades, exhibiting five different pulsed-field gel electrophoresis (PFGE) restriction patterns and a diverse composition of virulence genes. Six isolates harbored the virulence plasmid pYV. Besides two isolates, all isolates contained ail and inv genes and a complete or incomplete high-pathogenicity island (HPI). None of them possessed a gene for the superantigen YPM. The study shows that various Y. pseudotuberculosis strains exist in wild boars in northeast Germany, which may pose a risk to humans.IMPORTANCEYersinia pseudotuberculosis is a foodborne pathogen whose occurrence is poorly understood. One reason for this situation is the difficulty in isolating the species. The methods developed for the isolation of Yersinia enterocolitica are not well suited for Y. pseudotuberculosis We therefore designed a protocol which enabled the isolation of Y. pseudotuberculosis from a relatively high proportion of PCR-positive wild boar tonsils. The study indicates that wild boars in northeast Germany may carry a variety of Y. pseudotuberculosis strains, which differ in terms of their pathogenic potential and other properties. Since wild boars are widely distributed in German forests and even populate cities such as Berlin, they may transmit yersiniae to other animals and crop plants and may thus cause human infections through the consumption of contaminated food. Therefore, the prevalence of Y. pseudotuberculosis should be determined also in other animals and regions to learn more about the natural reservoir of this species.

Investigation of Yersinia pestis and Yersinia pseudotuberculosis strains from Georgia and neighboring countries in the Caucasus by high-density SNP microarray.

Yersinia pestis, the causative agent of plague, is a recently evolved clone of the enteropathogenic bacterium Yersinia pseudotuberculosis. Y. pestis has been extensively studied for decades; however, there are insufficient data about the intra-species diversity of this microorganism in certain parts of the world, including the Caucasus region. Using a high-density single-nucleotide polymorphism (SNP) microarray, we genotyped a total of 46 Y. pestis isolates from two plague foci in Georgia and neighboring Caucasus countries together with 12 Y. pseudotuberculosis isolates from Georgia. The genotyping microarray captured a total of 13,525 SNP positions across the Y. pestis and Y. pseudotuberculosis genomes and plasmids with high-throughput capability and superior reproducibility. From this analysis, we confirmed the presence of two independent and relatively distant phylogenetic groups of Y. pestis in the Caucasus region. The signature SNP patterns identified from this study will allow assay development for plague surveillance and pseudotuberculosis diagnostics.