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Introduction. Salmonella Kentucky sequence type ST198 is one of the epidemiologically significant non-typhoidal Salmonella clones worldwide and is characterized by the presence of highly resistant strains and the ability to adapt to different animal hosts and environmental conditions. The aim of this study was to analyze S. Kentucky strains isolated from various sources in Russia in terms of their phylogenetic position within the global diversity of the pathogen and their genetic characteristics. Materials and methods. We examined 55 strains of S. Kentucky by whole-genome sequencing, which were isolated from 2010 to 2022 from various sources (clinical strains, food, as well as from farm animals, feed and environmental samples). Whole genome sequencing was performed using Illumina platforms. Phylogenetic analysis based on nucleotide variation analysis included an additional 390 S. Kentucky strains. Results. Most of the Russian strains (n = 50) belonged to the ST198 sequence type, four strains were ST314 and one strain was ST152. Of the 50 Russian sequence-type ST198 strains, 44 belonged to the international monophyletic MDR lineage S. Kentucky ST198, and belonged to four separate sublineages, six strains occupying a basal position in relation to the MDR lineage. A total of 320 genes and mutations responsible for resistance to antimicrobial agents were identified. The most common were point mutations in the QRDR region. In most cases, Russian strains were characterized by the presence of variants of the SGI1-K genomic island. Moreover, the putative structure of SGI1 was correlated with the phylogenetic clustering of S. Kentucky sublineages. Conclusions. The results of the study made it possible to assess the population structure of Russian S. Kentucky ST198 strains on a global scale and determine the genetic determinants of antibiotic resistance, including the structure of the SGI1 genomic island.

ABSTRACT: Salmonella, which is widely distributed in nature, is an important zoonotic pathogen affecting humans, livestock, and other animals. Salmonella infection not only hinders the development of livestock and poultry-related industries but also poses a great threat to human health. In this study, we collected 1,537 samples including weak chicks, dead embryos, fecal samples and environmental samples from 2020 to 2023 (for a period of 1 to 2 months per year) to keep a long-term monitor the prevalence of Salmonella in an intensive laying hen farm, 105 Salmonella strains were isolated with an isolation rate of 6.83% (105/1,537). It revealed a significant decrease in prevalence rates of Salmonella over time (P < 0.001). Before 2020, the predominant serotype was S. Enteritidis. S. Kentucky was first detected in November 2020 and its proportion was gradually found to exceed that of S. Enteritidis since then. S. Kentucky isolates were distributed in various links of the four regions in the poultry farm. A total of 55 S. Kentucky strains, were assigned to ST198 based on whole genome sequencing. Among them, 54 strains were resistant to 12 to 16 antibiotics, indicating that they were extensively drug-resistant (XDR). Seventeen antimicrobial resistance genes were detected in 55 S. Kentucky isolates. For most of these isolates, antibiotic resistance phenotypes were concordant with their genotypes. All S. Kentucky strains isolated from this farm in 2020 to 2023 showed a high similarity based on their core-genome SNP-based phylogeny. The traceability analysis revealed that S. Kentucky was introduced to the farm through newly purchased flocks. The long-term existence of XDR S. Kentucky ST198 poses a substantial risk because of the multiage management and circulation of workers in this poultry farm. Thus, this study is the first to report extensively drug-resistant S. Kentucky ST198 detected in this intensive poultry farm in China.

Salmonella enterica serovar Kentucky (S. Kentucky) has been regarded as a common serotype causing human nontyphoidal salmonellosis, frequently associated with the consumption of contaminated poultry products. Recently, multidrug-resistant (MDR) S. Kentucky ST198 with strong resistance to cefotaxime, ciprofloxacin, and tigecycline has emerged and been frequently detected in both poultry and humans in Europe and Asia. In this study, whole-genome sequencing (WGS) analysis divided 327 S. Kentucky ST198 isolates into two clades, of which ST198.2 is more prevalent than ST198.1 worldwide. We further compared the genomic characteristics of 70 ST198 isolates from animals and humans during 2019-2022 plus previously reported 38 isolates from 2013 to 2019 in China. One hundred five of the 108 isolates were ST198.2, which could be differentiated into two subclades. ST198.2-1 was prevalent in isolates during 2013-2019, while ST198.2-2 has increased to be the predominant subclade in isolates since 2019. CRISPR typing can differentiate the clade ST198.1 isolates from clade ST198.2 ones but cannot differentiate the two subclade isolates. The acquisition of a large multi-drug resistant region in ST198.2-2 enhanced bacterial resistance to β-lactam, aminoglycoside, amphenicol, and fosfomycin. In addition, compared with the extendedspectrum β-lactamase (ESBL)-encoding gene blaCTX-M-14b in ST198.2-1, co-existence of blaCTX-M-55 and blaTEM-1B was detected in most of the ST198.2-2 isolates. The emergence of ciprofloxacin- and tigecycline-resistant ESBL-producing S. Kentucky ST198.2-2 strains highlight the necessity for Salmonella surveillance. It is imperative to implement more effective measures to prevent and control transmission of these strains from poultry to humans. Salmonella enterica serovar Kentucky (S. Kentucky) can cause human infections through consumption of contaminated food of animal origin, and the emergence of multidrug-resistant (MDR) ST198-S. Kentucky strains are of concern for human and animal health. Based on whole-genome sequencing (WGS) analysis, this study revealed that the clade ST198.2-2 S. Kentucky has increased to the predominant group in both chickens and humans in China since 2019, which is different to previous studies of the prevalent ST198.2-1 S. Kentucky before 2019. Acquirement of a multidrug resistance region (MRR) makes the ST198.2-2 S. Kentucky to be extensively drug-resistant (XDR) isolate compared with ST198.2-1 S. Kentucky. Besides, the ST198.2-2 S. Kentucky was mainly detected in chickens (chicken meat, intestinal contents, and slaughterhouse) and humans, indicating chicken is the main reservoir for these XDR S. Kentucky isolates. Therefore, it is necessary to implement continuous Salmonella surveillance and effective measures, such as the development of phages and novel antibiotics/compounds, to prevent the transmission of XDR ST198.2-2 S. Kentucky from chickens to humans across China. [ABSTRACT FROM AUTHOR]

Salmonella , which is widely distributed in nature, is an important zoonotic pathogen affecting humans, livestock, and other animals. Salmonella infection not only hinders the development of livestock and poultry-related industries but also poses a great threat to human health. In this study, we collected 1,537 samples including weak chicks, dead embryos, fecal samples and environmental samples from 2020 to 2023 (for a period of 1 to 2 months per year) to keep a long-term monitor the prevalence of Salmonella in an intensive laying hen farm, 105 Salmonella strains were isolated with an isolation rate of 6.83% (105/1,537). It revealed a significant decrease in prevalence rates of Salmonella over time (P < 0.001). Before 2020, the predominant serotype was S. Enteritidis. S. Kentucky was first detected in November 2020 and its proportion was gradually found to exceed that of S. Enteritidis since then. S. Kentucky isolates were distributed in various links of the four regions in the poultry farm. A total of 55 S. Kentucky strains, were assigned to ST198 based on whole genome sequencing. Among them, 54 strains were resistant to 12 to 16 antibiotics, indicating that they were extensively drug-resistant (XDR). Seventeen antimicrobial resistance genes were detected in 55 S. Kentucky isolates. For most of these isolates, antibiotic resistance phenotypes were concordant with their genotypes. All S. Kentucky strains isolated from this farm in 2020 to 2023 showed a high similarity based on their core-genome SNP-based phylogeny. The traceability analysis revealed that S. Kentucky was introduced to the farm through newly purchased flocks. The long-term existence of XDR S. Kentucky ST198 poses a substantial risk because of the multiage management and circulation of workers in this poultry farm. Thus, this study is the first to report extensively drug-resistant S. Kentucky ST198 detected in this intensive poultry farm in China. [ABSTRACT FROM AUTHOR]

Objective: Salmonella enterica serotype Kentucky ST198 (S. Kentucky) is frequently associated with human infections and has been identified in travellers to North Africa, South Asia, Europe, and North America. The antimicrobial resistance of this serotype to multiple drugs, including ciprofloxacin (CIP), is a growing concern. However, little information is available regarding the occurrence and characterization of S. Kentucky in Korea. Methods: To investigate the characteristics and possible origin of these infections, we characterized highly CIP-resistant S. Kentucky isolates collected through a national surveillance program. Single-nucleotide polymorphisms (SNPs) were identified by whole-genome sequencing (WGS), and genome sequencing was performed to investigate the genetic relationships and resistance mechanisms of the isolates. Results: Ten CIP-resistant S. Kentucky strains were isolated from diarrheal patients in Korea from 2008 to 2017. The travel histories of the patients indicated that seven had returned from Southeast Asia. WGS of all the isolates revealed the presence of Salmonella genomic island 1 (SGI1) and substitutions in the gyrA and parC genes, which are known to confer resistance to CIP. A multilocus sequence type (MLST) analysis revealed that the isolates belonged to ST198, which has been prevalent in Europe and Africa. Furthermore, a phylogenetic analysis showed that all 10 isolates shared close genetic relationships. Conclusions: We report the identification of S. Kentucky in Korea through long-term surveillance. International travel, especially to Southeast Asia, has been a major risk factor for human infections of CIP-resistant S. Kentucky in Korea.

The use of whole genome sequencing, standard analyze methods and international databases allows to detect international high-risk clones of food-borne pathogens, to assess their evolution and geographical distribution due to international trade of animal food products and farm animals. In Saint-Petersburg, Russian Federation, Salmonella Newport, Salmonella Kentucky and Escherichia coli O26:H11 of well-known international high-risk clones were first identified from patients with diarrhea. Two S. Kentucky strains isolated in 2015 and 2019 were identical to the international clone ST198 widely distributed in European countries: had multidrug resistance, high-level fluoroquinolone resistance (MIC of ciprofloxacin > 32,0 mg/l) due to three single-nucleotide substitutions in the gyrA (Ser83Phe and Asp87Asn) and parC (Ser80Ile). In 2008, a multidrug resistant S. Newport strain resistant to extended-spectrum cephalosporins due to AmpC-cephalosporinase CMY-2 was isolated, belonging to the international clone of S. Newport MDR-AmpC/CMY-2 which caused sporadic cases and outbreaks in the USA and Europe in the 2000s. The plasmid containing the blaCMY-2 had a PstI-restriction profile, one of the most prevalent in the international clone. E. coli O26:H11 strains, isolated in Saint-Petersburg, produced the shiga-like toxin STX1 (stx1a), had additional virulence genes: ehxA (enterohemolysin), katP (catalase peroxidase), espP (serine protease), as well as cba (colicin B), gad (glutamate decarboxylase), cif (type III secreted effector), iss (increased serum survival), belonged to the phylogenetic group B1 and the international high-risk clone E. coli O26:H11 ST21 widely distributed in Europe and the USA. 25% of the strains had multidrug resistance and produced CTX-M extended spectrum beta-lactamases. In the Russian Federation E. coli O26 is consider as the pathogen of diarrheal diseases and registered as Enteropathogenic E. coli in routine bacteriological laboratories without detecting of H-antigen and shiga-like toxins.

Introduction: Highly fluoroquinolone-resistant Salmonella enterica serovar Kentucky ( S. Kentucky) of sequence type (ST) 198 has emerged as a global multidrug-resistant (MDR) clone, posing a threat to public health., Methods: Whole genome sequencing and antibiotic susceptibility testing was used to characterize the population structure and evolutionary history of 54 S. Kentucky isolates recovered from food and human clinical cases in Beijing from 2016 to 2023., Results: All 54 S. Kentucky ST198 isolates exhibited resistance to quinolones, carrying point mutations in the quinolone resistance-determining regions ( gyrA &#95;S83F and parC &#95;S80I). Resistance to other antibiotics (folate pathway inhibitors, cephems, aminoglycosides, phenicols, rifamycin, fosfomycin, macrolides, and tetracyclines), mediated by the sul1 , sul2 , dfrA14 , bla CTX-M , bla TEM-1B , aac(3)-Id , aadA2 , aadA7 , aph(3')-I , aph(3'')-Ib , rmtB , floR , arr-2 , fosA , mph(A) Kentucky ST198 evolutionary tree was divided into clades 198.2-1 and 198.2-2, which were further differentiated into three subclades: 198.2-2A, 198.2-2B, and 198.2-2C. Compared with the extended-spectrum β-lactamase-encoding gene tet(A) genes, was also observed in different combinations. The Beijing S. Kentucky ST198 evolutionary tree was divided into clades 198.2-1 and 198.2-2, which were further differentiated into three subclades: 198.2-2A, 198.2-2B, and 198.2-2C. Compared with the extended-spectrum β-lactamase-encoding gene bla CTX-M-14b in 198.2-1, the co-existence of bla Kentucky ST198 outbreak isolates derived from two predominant clonal sources: 198.2-1 with cgST236434 and 198.2-2A with cgST296405.CTX-M-55 and bla TEM-1B , as well as chromosomally located qnrS1 , was detected in most 198.2-2 isolates, which showed more complex MDR phenotypes. S. Kentucky ST198 outbreak isolates derived from two predominant clonal sources: 198.2-1 with cgST236434 and 198.2-2A with cgST296405., Conclusions: The S. Kentucky population in Beijing is genetically diverse, consisting of multiple co-circulating lineages that have persisted since 2016. Strengthening surveillance of food and humans will aid in implementing measures to prevent and control the spread of AMR., (Copyright and License information: Editorial Office of CCDCW, Chinese Center for Disease Control and Prevention 2024.)

Salmonella enterica serovar Kentucky (S. Kentucky) with sequence type (ST) 198 and highly resistant to ciprofloxacin (ST198-Cip R ) has emerged as a global MDR clone, posing a threat to public health. In the present study, whole genome sequencing (WGS) was applied to characterize all Cip R S. Kentucky detected in five Spanish hospitals during 2009–2018. All Cip R isolates (n = 13) were ST198 and carried point mutations in the quinolone resistance-determining regions (QRDRs) of both gyrA (resulting in Ser83Phe and Asp87Gly, Asp87Asn, or Asp87Tyr substitutions in GyrA) and parC (with Thr57Ser and Ser80Ile substitutions in ParC). Resistances to other antibiotics (ampicillin, chloramphenicol, gentamicin, streptomycin, sulfonamides, and tetracycline), mediated by the bla TEM– 1 B , catA1, aacA5 , aadA7, strA , strB , sul1 , and tet (A) genes, and arranged in different combinations, were also observed. Analysis of the genetic environment of the latter resistance genes revealed the presence of multiple variants of SGI1 (Salmonella genomic island 1)-K and SGI1-P, where all these resistance genes except catA1 were placed. IS 26 elements, found at multiple locations within the SGI1 variants, have probably played a crucial role in their generation. Despite the wide diversity of SGI1-K- and SGI1-P-like structures, phylogenetic analysis revealed a close relationship between isolates from different hospitals, which were separated by a minimum of two and a maximum of 160 single nucleotide polymorphisms. Considering that S. enterica isolates resistant to fluoroquinolones belong to the high priority list of antibiotic-resistant bacteria compiled by the World Health Organization, continuous surveillance of the S. Kentucky ST198-CIP R clone is required. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Kentucky (S. Kentucky) with sequence type (ST) 198 and highly resistant to ciprofloxacin (ST198-CipR) has emerged as a global MDR clone, posing a threat to public health. In the present study, whole genome sequencing (WGS) was applied to characterize all CipRS. Kentucky detected in five Spanish hospitals during 2009–2018. All CipR isolates (n = 13) were ST198 and carried point mutations in the quinolone resistance-determining regions (QRDRs) of both gyrA (resulting in Ser83Phe and Asp87Gly, Asp87Asn, or Asp87Tyr substitutions in GyrA) and parC (with Thr57Ser and Ser80Ile substitutions in ParC). Resistances to other antibiotics (ampicillin, chloramphenicol, gentamicin, streptomycin, sulfonamides, and tetracycline), mediated by the blaTEM–1B, catA1, aacA5, aadA7, strA, strB, sul1, and tet(A) genes, and arranged in different combinations, were also observed. Analysis of the genetic environment of the latter resistance genes revealed the presence of multiple variants of SGI1 (Salmonella genomic island 1)-K and SGI1-P, where all these resistance genes except catA1 were placed. IS26 elements, found at multiple locations within the SGI1 variants, have probably played a crucial role in their generation. Despite the wide diversity of SGI1-K- and SGI1-P-like structures, phylogenetic analysis revealed a close relationship between isolates from different hospitals, which were separated by a minimum of two and a maximum of 160 single nucleotide polymorphisms. Considering that S. enterica isolates resistant to fluoroquinolones belong to the high priority list of antibiotic-resistant bacteria compiled by the World Health Organization, continuous surveillance of the S. Kentucky ST198-CIPR clone is required.

Non-typhoidal Salmonella (NTS) is a major cause of foodborne illness globally. Salmonella Kentucky is a polyphyletic NTS serovar comprised of two predominant multilocus sequence types (STs): ST152 and ST198. Epidemiological studies have revealed that ST152 is most prevalent in US poultry whereas ST198 is more prevalent in international poultry. Interestingly, ST152 is sporadically associated with human illness, whereas ST198 is more commonly associated with human disease. The goal of this study was to develop a better understanding of the epidemiology of ST198 and ST152 in WA State. We compared the antimicrobial resistance phenotypes and genetic relationship, using pulsed-field gel electrophoresis, of 26 clinical strains of S. Kentucky isolated in Washington State between 2004 and 2014, and 140 poultry-associated strains of S. Kentucky mostly recovered from the northwestern USA between 2004 and 2014. We also sequenced whole genomes of representative human clinical and poultry isolates from the northwestern USA. Genome sequences of these isolates were compared with a global database of S. Kentucky genomes representing 400 ST198 and 50 ST152 strains. The results of the phenotypic, genotypic, and case report data on food consumption and travel show that human infections caused by fluoroquinolone-resistant (FluR) S. Kentucky ST198 in WA State originated from outside of North America. In contrast, fluoroquinolone-susceptible (FluS) S. Kentucky ST198 and S. Kentucky ST152 infection have a likely domestic origin, with domestic cattle and poultry being the potential sources. We also identified lineage-specific non-synonymous single nucleotide polymorphisms (SNPs) that distinguish ST198 and ST152. These SNPs may provide good targets for further investigations on lineage-specific traits such as variation in virulence, metabolic adaptation to different environments, and potential for the development of intervention strategies to improve the safety of food.

ABSTRACT Salmonella enterica serotype Kentucky is frequently associated with high-level fluoroquinolone resistance and has gained epidemiological importance globally. A retrospective screening was performed to understand the national prevalence of ciprofloxacin-resistant S. Kentucky in China. S. enterica strains (n = 15,405) were collected within the frame of two national surveillance networks between 2013 and 2017. Thirty-three S. Kentucky strains were detected in 5 of 10 provinces, and 27 were assigned to sequence type 198 (ST198). The 27 isolates were multidrug resistant, with high-level resistance to ciprofloxacin, and 21 isolates were further resistant to extended-spectrum cephalosporins (ESCs). Phylogenomic analysis classified ST198 isolates into two clades (198.1 and 198.2), and recent occurrences of inter-/intraregion and interhost transmission were identified. Phylogenetic reconstruction with a global collection showed that one subclade of clade 198.2 was clustered with historical strains from Egypt, and the other one was clustered with strains from Southeast Asia. Isolates of clade 198.1 were clustered with strains isolated from North America. The various patterns of mutations detected in quinolone resistance-determining regions of GyrA and ParC are accordant with the phylogenetic structure. These findings indicate that our isolates may have various origins. SGI1 was exclusively detected in isolates of clade 198.2 with a highly mosaic structure, which were mainly identified as SGI1-K derivatives. Plasmid-mediated quinolone resistance genes qnrS1 and aac(6′)-Ib-cr were identified in three isolates, and blaCTX-M-9 and blaCTX-M-27 were detected in 20 of 21 ESC-resistant isolates. This is the first report of the genetic and epidemiological characterization for the S. Kentucky epidemic clone ST198 in China, warranting the necessity of surveillance for the high-risk clone. IMPORTANCE Ciprofloxacin and extended-spectrum cephalosporins are the choice for treatment of severe nontyphoidal S. enterica infections in adults. S. enterica serotype Kentucky ST198 has gained epidemiological importance globally, because the clone is frequently resistant to both of these high-level-resistance drug groups. The genetic and epidemiological characterization of S. Kentucky has been well studied in Western countries; however, the information is unclear for China. To fill in the gap, we here did a retrospective screening on a large collection in China, and ST198 isolates were systematically analyzed by whole-genome sequencing. Our study revealed that multidrug-resistant ST198 has spread in five provinces, and the occurrences of interregion and cross-host clonal disseminations were detected. Of note, phylogenomic analysis suggests that the Chinese isolates may have emerged with diverse origins, including Egypt, Southeast Asia, and North America. This study warrants the necessity of surveillance for the high-risk clone to prevent its further dissemination in China.

Background: Salmonella Kentucky belongs to zoonotic serotypes that demonstrate that the high antimicrobial resistance and multidrug resistance (including fluoroquinolones) is an emerging problem. To the best of our knowledge, clinical S. Kentucky strains isolated in Poland remain undescribed. Methods: Eighteen clinical S. Kentucky strains collected in the years 2018–2019 in Poland were investigated. All the strains were tested for susceptibility to 11 antimicrobials using the disc diffusion and E-test methods. Whole genome sequences were analysed for antimicrobial resistance genes, mutations, the presence and structure of SGI1-K (Salmonella Genomic Island and the genetic relationship of the isolates. Results: Sixteen of 18 isolates (88.9%) were assigned as ST198 and were found to be high-level resistant to ampicillin (>256 mg/L) and quinolones (nalidixic acid MIC ≥ 1024 mg/L, ciprofloxacin MIC range 6–16 mg/L). All the 16 strains revealed three mutations in QRDR of GyrA and ParC. The substitutions of Ser83 → Phe and Asp87 → Tyr of the GyrA subunit and Ser80→Ile of the ParC subunit were the most common. One S. Kentucky isolate had qnrS1 in addition to the QRDR mutations. Five of the ST198 strains, grouped in cluster A, had multiple resistant determinants like blaTEM1-B, aac(6′)-Iaa, sul1 or tetA, mostly in SGI1 K. Seven strains, grouped in cluster B, had shorter SGI1-K with deletions of many regions and with few resistance genes detected. Conclusion: The results of this study demonstrated that a significant part of S. Kentucky isolates from humans in Poland belonged to ST198 and were high-level resistant to ampicillin and quinolones.

Objectives: The aim of this study was to characterise the draft genome sequence of a multidrug-resistant (MDR) Salmonella enterica serotype Kentucky strain (XJ9S) isolated from a poultry slaughterhouse in China. Methods: The genome was sequenced using an Illumina HiSeq platform and was assembled using SPAdes_3.12.0. The CGE Bacterial Analysis Pipeline was used to identify the sequence type (ST) as well as the presence of antimicrobial resistance genes (ARGs) and plasmids in strain XJ9S. Gaps among contigs that carried MDR Salmonella genomic island 1 (SGI1) fragments were filled in by PCR linkage and sequencing. Results: The draft genome of strain XJ9S was assembled into 54 contigs with a total assembly size of 4 785 059 bp. XJ9S belonged to ST198 and harboured five acquired ARGs [blaCTX-M-14b, sul1, tetA(A), aacCA5 and aadA7]. The blaCTX-M-14b gene was located on a 2849-bp ISEcp1-mediated translocatable unit inserted in the chromosome. The other four acquired ARGs were carried by a new variant of SGI1 (SGI1-XJ9S; 38 593 bp) belonging to the SGI1-K group. Moreover, point mutations in the quinolone resistance-determining region (QRDR) were found at positions 83 (Ser83Phe) and 87 (Asp87Gly) of GyrA and at position 80 (Ser80Ile) of ParC. Conclusion: In this study, a new SGI1 variant (SGI1-XJ9S) was characterised for the first time. The draft genome sequence of S. Kentucky ST198 strain XJ9S isolated from a poultry slaughterhouse provides valuable information for tracing the potential spread of this MDR clone from poultry product processing to consumption, and even to humans.

• Isolates with chromosomally located bla CTX-M-14b form into a clade in China. • The qnrS1 gene transferred from a plasmid to the chromosome. • Being located on the chromosome causes stable existence of resistance genes. Highly fluoroquinolone-resistant Salmonella enterica serotype Kentucky has become widespread in recent years, largely associated with the spread of sequence type 198 (ST198), which often leads to multidrug resistance. Research on the genomic epidemiology of Salmonella Kentucky in China is currently uncommon. In this study, we analysed the genomic epidemiology and antimicrobial resistance characteristics of Salmonella Kentucky ST198 collected from foodborne disease surveillance in Shenzhen, China, during 2010–2021, using whole-genome sequencing and antibiotic susceptibility testing. In addition, 158 global Salmonella Kentucky ST198 genomes were included for comparison. Among 8559 Salmonella isolates, 43 Salmonella Kentucky ST198 isolates were detected during 2010–2021. The global Salmonella Kentucky ST198 evolutionary tree was divided into five clades, with Shenzhen isolates distributed in clades 198.1, 198.2-1 and 198.2-2, mainly clustered with Chinese strains. Strains in clade 198.2 dominated in Shenzhen and all of them showed multidrug resistance. Nine strains showed high resistance to ceftriaxone, which was associated with bla CTX-M-14b in clade 198.2-1, which was demonstrated to be located on the chromosome. Fifteen strains showed high resistance to ciprofloxacin, which was associated with carriage of qnrS1 in clade 198.2-2. qnrS1 was first located on an IncHI2 plasmid and then transferred into the chromosome. Here we report the genomic and antimicrobial resistance characterisation of Salmonella Kentucky ST198 in Shenzhen. Of particular concern, we identified for the first time a clade 198.2-1 isolate carrying bla CTX-M-14b as well as chromosomally located qnrS1 in clade 198.2-2 of Salmonella Kentucky ST198 in China, highlighting the necessity of surveillance of clade 198.2. [ABSTRACT FROM AUTHOR]

Salmonella enterica serovar Kentucky ( S. Kentucky) has been regarded as a common serotype causing human nontyphoidal salmonellosis, frequently associated with the consumption of contaminated poultry products. Recently, multidrug-resistant (MDR) S . Kentucky ST198 with strong resistance to cefotaxime, ciprofloxacin, and tigecycline has emerged and been frequently detected in both poultry and humans in Europe and Asia. In this study, whole-genome sequencing (WGS) analysis divided 327 S . Kentucky ST198 isolates into two clades, of which ST198.2 is more prevalent than ST198.1 worldwide. We further compared the genomic characteristics of 70 ST198 isolates from animals and humans during 2019-2022 plus previously reported 38 isolates from 2013 to 2019 in China. One hundred five of the 108 isolates were ST198.2, which could be differentiated into two subclades. ST198.2-1 was prevalent in isolates during 2013-2019, while ST198.2-2 has increased to be the predominant subclade in isolates since 2019. CRISPR typing can differentiate the clade ST198.1 isolates from clade ST198.2 ones but cannot differentiate the two subclade isolates. The acquisition of a large multi-drug resistant region in ST198.2-2 enhanced bacterial resistance to β-lactam, aminoglycoside, amphenicol, and fosfomycin. In addition, compared with the extended-spectrum β-lactamase (ESBL)-encoding gene bla in ST198.2-1, co-existence of CTX-M-14b in ST198.2-1, co-existence of bla was detected in most of the ST198.2-2 isolates. The emergence of ciprofloxacin- and tigecycline-resistant ESBL-producing CTX-M-55 . Kentucky ST198.2-2 strains highlight the necessity for bla TEM-1B was detected in most of the ST198.2-2 isolates. The emergence of ciprofloxacin- and tigecycline-resistant ESBL-producing S . Kentucky) can cause human infections through consumption of contaminated food of animal origin, and the emergence of multidrug-resistant (MDR) ST198- Salmonella . Kentucky strains are of concern for human and animal health. Based on whole-genome sequencing (WGS) analysis, this study revealed that the clade ST198.2-2 S. Kentucky has increased to the predominant group in both chickens and humans in China since 2019, which is different to previous studies of the prevalent ST198.2-1 Salmonella enterica . Kentucky before 2019. Acquirement of a multidrug resistance region (MRR) makes the ST198.2-2 S Kentucky to be extensively drug-resistant (XDR) isolate compared with ST198.2-1 S Kentucky. Besides, the ST198.2-2 S . Kentucky before 2019. Acquirement of a multidrug resistance region (MRR) makes the ST198.2-2 S. Kentucky to be extensively drug-resistant (XDR) isolate compared with ST198.2-1 S. surveillance and effective measures, such as the development of phages and novel antibiotics/compounds, to prevent the transmission of XDR ST198.2-2 S. Kentucky was mainly detected in chickens (chicken meat, intestinal contents, and slaughterhouse) and humans, indicating chicken is the main reservoir for these XDR S. Kentucky isolates. Therefore, it is necessary to implement continuous Salmonella surveillance and effective measures, such as the development of phages and novel antibiotics/compounds, to prevent the transmission of XDR ST198.2-2 S . Kentucky from chickens to humans across China., Competing Interests: The authors declare no conflict of interest.

While the spread of Salmonella enterica serotype Kentucky resistant to ciprofloxacin across Africa and the Middle-East has been described recently, the presence of this strain in humans, food, various animal species (livestock, pets, and wildlife) and in environment is suspected in other countries of different continents. Here, we report results of an in-depth molecular epidemiological study on a global human and non-human collection of S. Kentucky (n=70).We performed XbaI-pulsed field gel electrophoresis and multilocus sequence typing, assessed mutations in the quinolone resistance-determining regions, detected β-lactam resistance mechanisms, and screened the presence of the Salmonella genomic island 1 (SGI1). In this study, we highlight the rapid and extensive worldwide dissemination of the ciprofloxacin-resistant S. Kentucky ST198-X1-SGI1 strain since the mid-2000s in an increasingly large number of contaminated sources, including the environment. This strain has accumulated an increasing number of chromosomal and plasmid resistance determinants and has been identified in the Indian subcontinent, Southeast Asia and Europe since 2010. The second substitution at position 87 in GyrA (replacing the amino acid Asp) appeared helpful for epidemiological studies to track the origin of contamination.This global study provides evidence leading to the conclusion that high-level resistance to ciprofloxacin in S. Kentucky is a simple microbiological trait that facilitates the identification of the epidemic clone of interest, ST198-X1-SGI1. Taking this into account is essential in order to detect and monitor it easily and to take rapid measures in livestock to ensure control of this infection.

The purpose of this study was to characterize extensively drug-resistant Salmonella enterica serovar Kentucky sequence type 198 (ST198) isolates from chicken meat products. Ten S . Kentucky strains obtained from chicken meat products in Xuancheng, China, carried 12 to 17 resistance genes, such as bla CTX-M-55 , rmtB , tet (A), floR , and fosA3 , combined with mutations within gyrA (S83F and D87N) and parC (S80I), resulting in resistance to numerous antimicrobial agents, including the clinically important antibiotics cephalosporin, ciprofloxacin, tigecycline, and fosfomycin. These S . Kentucky isolates shared a close phylogenetic relationship (21 to 36 single-nucleotide polymorphisms [SNPs]) and showed close genetic relatedness to two human clinical isolates from China. Three S . Kentucky strains were subjected to whole-genome sequencing using Pacific Biosciences (PacBio) single-molecule real-time (SMRT) technology. All antimicrobial resistance genes were located on their chromosomes and clustered in one multiresistance region (MRR) and Salmonella genomic island (SGI) SGI1-K. The MRRs in three S . Kentucky strains were bounded by IS 26 at both ends and were inserted downstream of the bcfABCDEFG cluster with 8-bp direct repeats. The MRRs were related to those of IncHI2 plasmids but differed by insertions, deletions, and rearrangements of multiple segments involving resistance genes and plasmid backbones. This finding suggests that the MRR fragment possibly originates from IncHI2 plasmids. Four SGI1-K variants with slight differences were identified in 10 S . Kentucky strains. Mobile elements, particularly IS 26 . Kentucky ST198 strains containing numerous chromosomally located resistance genes is alarming and needs continued surveillance. S . Kentucky ST198 strains containing numerous chromosomally located resistance genes is alarming and needs continued surveillance. IMPORTANCE . Kentucky ST198 strains have been increasingly reported from various sources and have become a global risk. In this study, we described extensively drug-resistant S . Kentucky ST198 strains from chicken meat products from a city in China. Numerous resistance genes are clustered in the chromosomes of S . Kentucky ST198 strains, possibly acquired with the help of mobile elements. This would facilitate the spread of numerous resistance genes as intrinsic chromosomal genes within this global epidemic clone, with the potential to capture more resistance genes. The emergence and dissemination of extensively drug-resistant S . Kentucky ST198 pose a severe clinical and public health threat; therefore, continuous surveillance is warranted.S . Kentucky ST198 pose a severe clinical and public health threat; therefore, continuous surveillance is warranted.

Introduction: This study investigated the antimicrobial resistance and clonality of Salmonella enterica serotype Kentucky in poultry and poultry sources in Nigeria, and compared the isolates with the clone of S. Kentucky STI98-X1 CIPR using (PFGE) and (MIC). Methodology: Fecal samples from chickens and poultry sources (litter, water, rodent and lizard fecal samples) were collected from fourteen (14) poultry farms in 2007, 2010 and 2011 and were analyzed for S. Kentucky. Results and conclusions: Six percent of the samples were positive for S. Kentucky -- all resistant to nalidixic acid and ciprofloxacin. The isolates are grouped within the PFGE cluster X1 of S. Kentucky STI98 CIPR, indicating the association to the emerging and widely spread CIPR S. Kentucky clone with poultry and poultry sources. [ABSTRACT FROM AUTHOR]

Salmonella serovar Kentucky is frequently isolated from chickens and dairy cattle, but recovery from humans is comparatively low based on the U.S. National Antimicrobial Resistance Monitoring System (NARMS) reports. We aimed to better describe the genetic diversity, antimicrobial resistance, and virulence determinants of Salmonella Kentucky isolates from humans, food animal ceca, retail meat and poultry products, imported foods and food products, and other samples. We analyzed the genomes of 774 Salmonella Kentucky isolates and found that 63% (54/86) of human isolates were sequence type (ST)198, 33% (29/86) were ST152, and 3.5% (3/86) were ST314. Ninety-one percent (570/629) of cecal isolates and retail meat and poultry isolates were ST152 or ST152-like (one allele difference), and 9.2% (58/629) were ST198. Isolates from imported food were mostly ST198 (60%, 22/37) and ST314 (29.7%, 11/37). ST198 isolates clustered into two main lineages. Clade ST198.2 comprised almost entirely isolates from humans and imported foods, all containing triple mutations in the quinolone resistance-determining region (QRDR) that confer resistance to fluoroquinolones. Clade ST198.1 contained isolates from humans, ceca, retail meat and poultry products, and imported foods that largely lacked QRDR mutations. ST152 isolates from cattle had a lineage (Clade 2) distinct from ST152 isolates from chicken (Clade 4), and half of ST152 human isolates clustered within two other clades (Clades 1 and 3), largely distinct from Clades 2 and 4. Although clinical illness associated with Salmonella Kentucky is low, ST198 appears to account for most human infections in the Unites States but is uncommon among ceca of domestic food animals and retail meat and poultry products. These findings, combined with human exposure data, suggest that fluoroquinolone-resistant ST198 infections may be linked to the consumption of food products that are imported or consumed while traveling. We also found unique differences in the composition of virulence genes and antimicrobial resistance genes among the clades, which may provide clues to the host specificity and pathogenicity of Salmonella Kentucky lineages.

Background: Salmonella Kentucky belongs to zoonotic serotypes that demonstrate that the high antimicrobial resistance and multidrug resistance (including fluoroquinolones) is an emerging problem. To the best of our knowledge, clinical S. Kentucky strains isolated in Poland remain undescribed. Methods: Eighteen clinical S. Kentucky strains collected in the years 2018–2019 in Poland were investigated. All the strains were tested for susceptibility to 11 antimicrobials using the disc diffusion and E-test methods. Whole genome sequences were analysed for antimicrobial resistance genes, mutations, the presence and structure of SGI1-K (Salmonella Genomic Island and the genetic relationship of the isolates. Results: Sixteen of 18 isolates (88.9%) were assigned as ST198 and were found to be high-level resistant to ampicillin (>256 mg/L) and quinolones (nalidixic acid MIC ≥ 1024 mg/L, ciprofloxacin MIC range 6–16 mg/L). All the 16 strains revealed three mutations in QRDR of GyrA and ParC. The substitutions of Ser83 → Phe and Asp87 → Tyr of the GyrA subunit and Ser80→Ile of the ParC subunit were the most common. One S. Kentucky isolate had qnrS1 in addition to the QRDR mutations. Five of the ST198 strains, grouped in cluster A, had multiple resistant determinants like blaTEM1-B, aac(6′)-Iaa, sul1 or tetA, mostly in SGI1 K. Seven strains, grouped in cluster B, had shorter SGI1-K with deletions of many regions and with few resistance genes detected. Conclusion: The results of this study demonstrated that a significant part of S. Kentucky isolates from humans in Poland belonged to ST198 and were high-level resistant to ampicillin and quinolones. [ABSTRACT FROM AUTHOR]

Objective: Salmonella enterica serotype Kentucky ST198 (S. Kentucky) is frequently associated with human infections and has been identified in travellers to North Africa, South Asia, Europe, and North America. The antimicrobial resistance of this serotype to multiple drugs, including ciprofloxacin (CIP), is a growing concern. However, little information is available regarding the occurrence and characterization of S. Kentucky in Korea., Methods: To investigate the characteristics and possible origin of these infections, we characterized highly CIP-resistant S. Kentucky isolates collected through a national surveillance program. Single-nucleotide polymorphisms (SNPs) were identified by whole-genome sequencing (WGS), and genome sequencing was performed to investigate the genetic relationships and resistance mechanisms of the isolates., Results: Ten CIP-resistant S. Kentucky strains were isolated from diarrheal patients in Korea from 2008 to 2017. The travel histories of the patients indicated that seven had returned from Southeast Asia. WGS of all the isolates revealed the presence of Salmonella genomic island 1 (SGI1) and substitutions in the gyrA and parC genes, which are known to confer resistance to CIP. A multilocus sequence type (MLST) analysis revealed that the isolates belonged to ST198, which has been prevalent in Europe and Africa. Furthermore, a phylogenetic analysis showed that all 10 isolates shared close genetic relationships., Conclusions: We report the identification of S. Kentucky in Korea through long-term surveillance. International travel, especially to Southeast Asia, has been a major risk factor for human infections of CIP-resistant S. Kentucky in Korea., (Copyright © 2020 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Objectives: The aim of this study was to characterise the draft genome sequence of a multidrug-resistant (MDR) Salmonella enterica serotype Kentucky strain (XJ9S) isolated from a poultry slaughterhouse in China., Methods: The genome was sequenced using an Illumina HiSeq platform and was assembled using SPAdes&#95;3.12.0. The CGE Bacterial Analysis Pipeline was used to identify the sequence type (ST) as well as the presence of antimicrobial resistance genes (ARGs) and plasmids in strain XJ9S. Gaps among contigs that carried MDR Salmonella genomic island 1 (SGI1) fragments were filled in by PCR linkage and sequencing., Results: The draft genome of strain XJ9S was assembled into 54 contigs with a total assembly size of 4 785 059 bp. XJ9S belonged to ST198 and harboured five acquired ARGs [bla CTX-M-14b , sul1, tetA(A), aacCA5 and aadA7]. The bla CTX-M-14b gene was located on a 2849-bp ISEcp1-mediated translocatable unit inserted in the chromosome. The other four acquired ARGs were carried by a new variant of SGI1 (SGI1-XJ9S; 38 593 bp) belonging to the SGI1-K group. Moreover, point mutations in the quinolone resistance-determining region (QRDR) were found at positions 83 (Ser83Phe) and 87 (Asp87Gly) of GyrA and at position 80 (Ser80Ile) of ParC., Conclusion: In this study, a new SGI1 variant (SGI1-XJ9S) was characterised for the first time. The draft genome sequence of S. Kentucky ST198 strain XJ9S isolated from a poultry slaughterhouse provides valuable information for tracing the potential spread of this MDR clone from poultry product processing to consumption, and even to humans., (Copyright © 2019 International Society for Antimicrobial Chemotherapy. Published by Elsevier Ltd. All rights reserved.)

Salmonella enterica serotype Kentucky can be a common causative agent of salmonellosis, usually associated with consumption of contaminated poultry. Antimicrobial resistance (AMR) to multiple drugs, including ciprofloxacin, is an emerging problem within this serotype. We used whole-genome sequencing (WGS) to investigate the phylogenetic structure and AMR content of 121 S.enterica serotype Kentucky sequence type 198 isolates from five continents. Population structure was inferred using phylogenomic analysis and whole genomes were compared to investigate changes in gene content, with a focus on acquired AMR genes. Our analysis showed that multidrug-resistant (MDR) S.enterica serotype Kentucky isolates belonged to a single lineage, which we estimate emerged circa 1989 following the acquisition of the AMR-associated Salmonella genomic island (SGI) 1 (variant SGI1-K) conferring resistance to ampicillin, streptomycin, gentamicin, sulfamethoxazole and tetracycline. Phylogeographical analysis indicates this clone emerged in Egypt before disseminating into Northern, Southern and Western Africa, then to the Middle East, Asia and the European Union. The MDR clone has since accumulated various substitution mutations in the quinolone-resistance-determining regions (QRDRs) of DNA gyrase (gyrA) and DNA topoisomerase IV (parC), such that most strains carry three QRDR mutations which together confer resistance to ciprofloxacin. The majority of AMR genes in the S. enterica serotype Kentucky genomes were carried either on plasmids or SGI structures. Remarkably, each genome of the MDR clone carried a different SGI1-K derivative structure; this variation could be attributed to IS26-mediated insertions and deletions, which appear to have hampered previous attempts to trace the clone's evolution using sub-WGS resolution approaches. Several different AMR plasmids were also identified, encoding resistance to chloramphenicol, third-generation cephalosporins, carbapenems and/or azithromycin. These results indicate that most MDR S. enterica serotype Kentucky circulating globally result from the clonal expansion of a single lineage that acquired chromosomal AMR genes 30 years ago, and has continued to diversify and accumulate additional resistances to last-line oral antimicrobials. This article contains data hosted by Microreact.

While the spread of Salmonella enterica serotype Kentucky resistant to ciprofloxacin across Africa and the Middle-East has been described recently, the presence of this strain in humans, food, various animal species (livestock, pets, and wildlife) and in environment is suspected in other countries of different continents. Here, we report results of an in-depth molecular epidemiological study on a global human and non-human collection of S. Kentucky (n = 70). We performed XbaI-pulsed field gel electrophoresis and multilocus sequence typing, assessed mutations in the quinolone resistance-determining regions, detected β-lactam resistance mechanisms, and screened the presence of the Salmonella genomic island 1 (SGI1). In this study, we highlight the rapid and extensive worldwide dissemination of the ciprofloxacin-resistant S. Kentucky ST198-X1-SGI1 strain since the mid-2000s in an increasingly large number of contaminated sources, including the environment. This strain has accumulated an increasing number of chromosomal and plasmid resistance determinants and has been identified in the Indian subcontinent, Southeast Asia and Europe since 2010. The second substitution at position 87 in GyrA (replacing the amino acid Asp) appeared helpful for epidemiological studies to track the origin of contamination. This global study provides evidence leading to the conclusion that high-level resistance to ciprofloxacin in S. Kentucky is a simple microbiological trait that facilitates the identification of the epidemic clone of interest, ST198-X1-SGI1. Taking this into account is essential in order to detect and monitor it easily and to take rapid measures in livestock to ensure control of this infection.