Virulence-associated Gene Profiles Research Articles

Genome-wide expanding of genetic evolution and potential pathogenicity in Vibrio alginolyticus

ABSTRACT Vibrio alginolyticus, an emergent species of Vibrio genus, exists in aquatic and marine environments. It has undergone genetic diversification, but its detailed genomic diversity is still unclear. Here, we performed a multi-dimensional comparative genomic analysis to explore the population phylogeny, virulence-related genes and potential drug resistance genes of 184 V. alginolyticus isolates. Although genetic diversity is complex, we analysed the population structure using three sub-datasets, including the subdivision for three lineages into sublineages and the distribution of strains in the marine ecological niche. Accessory genes, most of which reclassified V. alginolyticus genomes as different but with relatively close affinities, were nonuniformly distributed among these isolates. We demonstrated that the spread of some post-evolutionary isolates (mainly L3 strains isolated from Chinese territorial seas) was likely to be closely related to human activities, whereas other more ancestral strains (strains in the L1 and L2) tended to be locally endemic and formed clonal complex groups. In terms of pathogenicity, the potential virulence factors were mainly associated with toxin, adherence, motility, chemotaxis, and the type III secretion system (T3SS). We also found five types of antibacterial drug resistance genes. The prevalence of β-lactam resistance genes was 100%, which indicated that there may be a potential risk of natural resistance to β-lactam drugs. Our study reveals insights into genomic characteristics, evolution and potential virulence-associated gene profiles of V. alginolyticus.

Human Keratinocyte Entry of Noninvasive Streptococcus dysgalactiae Subsp. equisimilis from Humans and Companion Animals: Relatedness with Lancefield Group, Source, Virulence-Associated Genes, and Antimicrobial Resistance Phenotype.

We evaluated the cell invasion ability (CIA) of non-invasive Streptococcus dysgalactiae subsp. equisimilis using human keratinocytes and determined the association of CIA populations with their hosts and microbiological traits. Forty-two isolates from humans and companion animals were selected with host information. In addition to CIA, virulence-associated gene (VAG, spegg-ska-scpA-inlA-sicG-brpA-prtF1-prtF2-lmb-cbp-srtp1-srtp2) profiling, emm genotyping, multilocus sequence typing, and antimicrobial resistance (AMR) phenotyping/genotyping were performed. We designated CIA values higher than the mean of all isolates as high-frequency and those lower than the mean as low-frequency. Differences in the CIA between the different sources and Lancefield groups were assessed. We analyzed the association between high- and low-frequency CIA and VAG, emm genotype, sequence type/clonal complex, and AMR phenotype/genotype. Based on the mean (19.368 colony-forming units/100 cells) of 42 isolates, eight isolates had high-frequency CIA, whereas 34 had low-frequency CIA. We found an association between low-frequency CIA population and group G isolates, as well as a link between high-frequency CIA population and group C isolates. We also observed associations between low-frequency CIA population and oral/respiratory tract origin, ska, scpA, and lmb detection, and the AMR phenotype. Our observations suggest potential associations between high-/low-frequency CIA and the group, source, VAG, and AMR phenotypes.

Pathology, virulence associated gene profiling, antimicrobial susceptibility and pathogenicity of untypeable capsular serotypes of Pasteurella multocida isolated from slaughtered pigs of India.

Pasteurella multocida is widely distributed in all pig-rearing countries, affecting the economic viability and profitability of pig production. The present research highlights the molecular characterization and pathology of untypeable capsular serotypes of P. multocida in slaughtered pigs from prominent pig-rearing states of India. The prevalence of Pasteurellosis was 27.17% by PM-PCR assay, while isolation rate was 7.62%. The microscopic lesions of bronchopneumonia, tonsillitis, and the presence of bacterial antigens in IHC confirmed P. multocida with pathologies. In capsular typing, the majority of the isolates were untypeable with prevalence of 52.15% and 43.58% in molecular and microbiological methods respectively. All the isolates showed the uniform distribution of virulence genes such as exbB, nanB, sodC, plpB, and oma87 (100%), while the variations were observed in ptfA, hasR, ptfA, pfhA, hsf-1, and plpE genes. The untypeable isolates showed higher prevalence of hsf-1 gene as compared to others. The untypeable serotypes showed a higher degree of resistance to ampicillin, amoxicillin, and penicillin antibiotics. The mouse pathogenicity testing of untypeable capsular isolates confirmed its pathogenic potential. The higher frequency of pathogenic untypeable isolates with antibiotic resistance profile might pose a serious threat to the pigs, and therefore, preventive measures should be adopted for effective control.

Genomic comparison of two Streptococcus suis serotype 1 strains recovered from porcine and human disease cases

Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. Although S. suis serotype 2 strains are most prevalent worldwide, other serotypes are also occasionally detected. Herein, we investigated the genomes of two S. suis serotype 1 strains belonging to the clonal complex 1, which were recovered from a human patient and an asymptomatic pig, respectively. The genomes differed in pathotype, virulence-associated gene (VAG) profile, minimum core genome (MCG) typing, and antimicrobial resistance gene content. The porcine serotype 1 strain was sequence type (ST) 237 and MCG1, whereas the human serotype 1 strain was ST105 and MCG ungroupable. Both strains were susceptible to several antibiotics consisting of β-lactams, fluoroquinolones, and chloramphenicol. Resistance to tetracycline, macrolides, and clindamycin was observed, which was attributed to the genes tet(O) and erm(B). Analysis of 99 VAG revealed Hhly3, NisK, NisR, salK/salR, srtG, virB4, and virD4 were absent in both serotype 1. However, the porcine strain lacked sadP (Streptococcal adhesin P), whereas the human strain harbored sadP1. Phylogenetic analysis revealed that human S. suis ST105 strains from Vietnam were genetically the closest to the human serotype 1 strain, whereas porcine S. suis ST11 strains from China and Thailand were genetically the closest to the porcine strain.

Molecular Epidemiology of Pasteurella multocida Associated with Bovine Respiratory Disease Outbreaks

Studies that characterize bovine respiratory disease (BRD)-associated Pasteurella multocida isolates are scarce compared with research on isolates from other hosts and clinical backgrounds. In the present study, 170 P. multocida isolates from 125 BRD outbreaks were characterized by capsular and LPS typing as well as by virulotyping. Three capsular types (A, B, F) and three LPS genotypes (L2, L3, L6) were identified. Capsular and LPS typing revealed a very low genetic diversity (GD = 0.02) among P. multocida, with most isolates belonging to genotype A:L3 (97.6%). Virulotyping identified seven virulence-associated gene profiles, with two profiles including 95.9% of the isolates. A subset of isolates was further characterized by MLST and PFGE. The sequence types ST79 and ST13 were the most frequently identified and were grouped into the same clonal complex (CC13), a result that supports the clonal population structure of BRD-associated P. multocida isolates. PFGE typing also revealed a low genetic diversity (GD = 0.18), detecting a single pattern in 62.5% of the outbreaks in which multiple isolates were analyzed. Overall, 85.2% of the isolates belonged to pulsotypes with at least 80% genetic similarity, consistent with a clonal population structure observed by MLST analysis and corroborating the genetic relatedness of most P. multocida isolates associated with BRD in cattle.

Biofilm Production Ability and Other Microbiological Features of Streptococcus canis.

This study assessed the biofilm production ability (BPA) and other microbiological features of Streptococcus canis strains. Forty strains of companion-animal origin, including the host information, from 2015 and 2017 were randomly selected, and three strains of blood-origin from two humans and one dog were included. We measured BPA using crystal violet staining, along with S. canis M-like protein (SCM) allele typing, sequence type (ST) determination, antimicrobial resistance (AMR) phenotyping/genotyping, and virulence-associated gene profiling (gbp, ap1, fp1, and brp). BPA measurements revealed 35 strains with BPA and 48 strains without BPA. There was an association between the producer and the isolation year (2017). Moreover, we observed an association between the non-producer and SCM allele 1 and ST9, and between the producer and SCM allele 10 and ST21. Furthermore, we observed a correlation between the producer and the presence of AMR genotypes. Specifically, there was an association between the producer and ap1 detection, and between non-producer and gbp detection. Our results suggest a correlation between biofilm producers and other microbiological features (i.e. isolation year, SCM allele type 10, ST21, presence of AMR genotypes, and ap1 detection).

Genomic Characterization of Streptococcus suis Serotype 24 Clonal Complex 221/234 From Human Patients.

Streptococcus suis is a zoonotic pathogen that causes invasive infections in humans and pigs. Although S. suis serotype 2 is prevalent among patient and swine infections, other serotypes are occasionally detected in humans. Of these, serotype 24 clonal complex (CC) 221/234 are recognized as emerging clones of human infection. Genomic exploration of three S. suis serotype 24 CC221/234 strains revealed antimicrobial resistance genes, pathotyping, virulence-associated gene (VAG) profiles, minimum core genome (MCG) typing, and comparison of the genomes. Based on these analyzes, all three serotype 24 strains were MCG7-3 and should be classified in the intermediate/weakly virulent (I/WV) group. All selected serotype 24 strains were susceptible to several antibiotics including β-lactam, fluoroquinolone, and chloramphenicol. Resistance to tetracycline, macrolide, and clindamycin was observed and attributed to the genes tet(O) and erm(B). Genomic comparison revealed the strains S12X, LSS66, LS0L, LS0E, 92–4,172, and IMT40201 that had phylogenetic affinity with serotype 24 CC221/234. Analysis of 80 virulence-associated genes (VAG) showed that all three serotype 24 strains lacked 24 genes consisting of adhesin P, epf, hyl, ihk, irr, mrp, nadR, neuB, NisK/R, ofs, permease (SSU0835), rgg, revS, salK/R, sao, sly, spyM3_0908, srtBCD, srtF, srtG, SSU05_0473, virA, virB4, and virD4. Eleven specific sequences were identified in the 3 serotype 24 genomes that differed from the genomes of the representative strains of epidemic (E; SC84), highly virulent (HV; P1/7), I/WV (89–1,591), and avirulent (T15 and 05HAS68).

Investigation of the nontypical Pasteurella multocida strains obtained from multiple sources, regions, and times: an unexpected increase was detected

In this study, it was aimed to isolate Pasteurella multocida from 1250 lung samples (calf, sheep, and goat), with respiratory system infection, such as nasal discharge, cough, fever, and to investigate the phenotypic and genotypic properties of this bacteria. As a result, a total of 92 P. multocida were obtained, of which 66 (71.73%) were from calf, 19 (20.65%) from sheep, and 7 (7.6%) from goat. The A:3A type was the most common type with 34 isolates (36.95%), including 30 from calves (45.45%), and 4 from sheep (21.05%). An alternate mPCR protocol was developed to determine capB and capE genes and 5 from 41 nontypical strains were detected as type B (n = 3; 3.26%) and type E (n = 2; 2.17%) via this novel protocol. Twenty-six nontypical strains presented nonmucoid colonies. The serotype of 11 typical and 13 nontypical strains was not able to be determined by mPCR. The prevalences of nontypical P. multocida were significantly (p < 0.01) different by determinants. Nineteen virulence-associated gene profiles were determined, and the highest percentages of genes were ompA (70.65%), ptfA (69.56%), and tadD (64.13%). Also, there was a higher rate of similarity between calf and sheep strains. In conclusion, nontypical strains may commonly cause pneumonia in farm animals. These results may be considered for future vaccine studies.

Virulence-Associated Gene Profiles of Escherichia coli Isolated from Chickens with Colibacillosis in Japan and Their Correlation with Pathogenicity in Chicken Embryos

Colibacillosis, an infectious disease of chickens, is caused by avian pathogenic Escherichia coli (APEC); however, in addition to APEC, other pathogens are also frequently isolated from chickens affected with colibacillosis. Therefore, experimental infections in chickens are necessary to evaluate the pathogenicity of APEC isolates. Recent studies have shown that embryo lethality assays can be used as an alternative method to evaluate the pathogenicity of E. coli. In this study, to determine the important virulence genes associated with the pathogenicity of E. coli, 67 strains of E. coli that possessed different combinations of eight representative virulence genes (cva/cvi, vat, tsh, iucD, papC, irp2, iss, and astA) were isolated from broilers with colibacillosis in Japan, and the chicken embryo lethal assay was conducted. The genes vat, papC, and irp2 showed strong correlation with the level of virulence in E. coli. Our study provides useful information about the important virulence-associated genes in relation to the pathogenicity of E. coli in Japanese chickens.

Survival patterns of Streptococcus suis serotypes 1 and 14 in porcine blood indicate cross-reactive bactericidal antibodies in naturally infected pigs

Streptococcus suis serotype (cps) 1 and cps14 have been detected in association with severe diseases such as meningitis and polyarthritis in pigs. Though these two cps are very similar, only cps14 is an important zoonotic agent in Asia and only cps1 is described to be associated with diseases in suckling piglets rather than weaning piglets. The main objective of this study was to assess restriction of survival of cps14 and cps1 in porcine blood by IgG and IgM putatively cross-reacting with these two cps. Furthermore, we differentiate recent European cps1/14 strains by agglutination, cpsK sequencing, MLST and virulence-associated gene profiling. Our data confirmed cps1 of clonal complex 1 as an important pathotype causing polyarthritis in suckling piglets in Europe. The experimental design included also bactericidal assays with blood samples drawn at different ages of piglets naturally infected with different S. suis cps types including cps1 but not cps14. We report survival of a cps1 and a cps14 strain (both of sequence type 1) in blood of suckling piglets with high levels of maternal IgG binding to the bacterial surface. In contrast, killing of cps1 and cps14 was recorded in older piglets due to an increase of IgM as demonstrated by specific cleavage of IgM. Heterologous absorption of antibodies with cps1 or cps14 is sufficient to significantly increase the survival of the other cps. In conclusion, IgM elicited by natural S. suis infection is crucial for killing of S. suis cps1 and cps14 in older weaning piglets and has most likely the potential to cross-react between cps1 and cps14.

Virulence associated gene profiling and antimicrobial resistance pattern of Streptococcus suis isolated from clinically healthy pigs from North East India.

This study revealed the prevalence of Streptococcus suis in 20·39% clinically healthy pigs from North East India. All these isolates were screened for the presence of virulence- associated genes such as suilysin (sly), muramidase released protein (mrp), extracellular protein factor (epf) and arginine deiminase (arcA). Of these 62 isolates, 29 isolates carried mrp gene, 17 isolates carried sly gene, 57 isolates carried arcA gene, whereas all isolates were negative for epf gene. The most prevalent genotype was mrp- sly- epf- arcA+ (45·16%) followed by genotypes mrp+ sly- epf- arcA+ (27·41%), mrp+ sly+ epf- arcA+ (19·35%) and mrp- sly+ epf- arcA- (8·06%). High frequency of resistance was observed for antimicrobials such as tetracycline (93·54%), clindamycin (91·93%), co-trimoxazole (88·70%) and erythromycin (85·48%). Antimicrobial resistance patterns of the S. suis isolates revealed 16 resistance groups (R1 to R16), where 93·54% isolates showed multi-drug resistance (≥3 antimicrobial agents). It has also been observed that 57 (91·93%) isolates were resistant to at least four antimicrobials. The most predominant resistance pattern observed was CD-COT-E-TE, which accounted for 38·70% of the isolates. The occurrence of relatively high levels of resistance of S. suis to some antimicrobials (e.g., macrolides, tetracyclines, and sulphonamides) as observed in this study may represent a human health concern. In addition, a relatively higher percentage of S. suis isolated from clinically healthy pigs indicates a carrier status with risk of dissemination to other pigs in the herd as well as to humans.

Biofilm production ability and associated characteristics of Streptococcus agalactiae isolates from companion animals and humans

ObjectiveWe evaluated biofilm production ability (BPA) of Streptococcus agalactiae isolates from companion animals/humans and clarified the relationship between BPA populations and other microbiological features. MethodsCompanion animal-/human-origin isolates were collected with host information. We measured BPA using crystal violet staining, via virulence-associated gene profiling (hylB-pavA-pilB-spb1-srtC1-brpA), capsular genotyping, multilocus sequence typing, and antimicrobial resistance (AMR) phenotyping/genotyping. Significant difference in BPA of isolates from different hosts was assessed. We analyzed the association between BPA populations and the virulence genotypes, capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes. Inhibitory effect of berberine on BPA was evaluated. ResultsFive, twenty-six, and twenty-six isolates belonged to strong, moderate, and weak biofilm producers, whereas seventeen showed no biofilm production. We defined strong, moderate, or weak biofilm producers as the producer group (n = 57) to conduct a comparative analysis between the producer and non-producer populations. There was a significant correlation between the producer population and vaginal specimen. We found significant associations between the producer group and presence (57.9%) of pilB and between the non-producer population and presence (70.6%) of spb1. There was no association between the producer group and capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes (except for a significant correlation between the producer group and AMR to minocycline). We confirmed inhibitory effect of berberine at sub-minimum inhibitory concentrations (MICs) against the type strain on BPA. ConclusionOur observations suggest that S. agalactiae harboring pilB is more capable of producing biofilms, with berberine inhibitory effect at sub-MICs on BPA.

Detection of virulence genes of APEC (avian pathogenic Escherichia coli) isolated from poultry in Noakhali, Bangladesh

Avian colibacillosis, caused by avian pathogenic Escherichia coli (APEC), is one of the major infectious diseases of poultry that bring about great economic loss for the Bangladesh poultry industry. The present study aimed to determine the virulence genes of avian pathogenic Escherichia coli (APEC) from cases of colibacillosis in poultry at the Noakhali district of Bangladesh. Currently, virulence-associated gene profiles of APEC isolates were investigated by polymerase chain reaction (PCR). A total of 24 (twenty-four) Escherichia coli isolates were collected and presumptively identified from 8 (eight) colibacillosis cases from 4 commercial broiler poultry farms (2 broilers per farm) in Noakhali, Bangladesh. The pathogenesis of Escherichia coli involves a wide range of different virulence genes. At this point, four virulence genes, iutA, hlyF, iroN, and iss were detected by PCR analysis. It has been observed that iutA, iss, hlyF, and iroN genes were found in 7(29.16%), 20(83.33%), 22(91.66%), and 24(100%) APEC isolates respectively. Furthermore, out of the twenty-four APEC isolates, six (25%) isolates had four virulence genes, fourteen (58.33%) isolates carried at least three virulence genes, three (12.5%) isolates carried two genes and one (4.16%) isolates had one virulence gene. Most importantly. six types of virulence gene profiles existed within the APEC isolates from which profile number 3 (hlyF, iroN, iss) having 13 (54.16%) isolates were predominant. The occurrence of APEC isolates of this region which is responsible for avian colibacillosis cases can be a matter of concern from the public health point of view. Future investigations will be able to utilize these virulence genes to identify APEC in Bangladesh helping in the diagnosis and prevention of colibacillosis in poultry.&#x0D; Bioresearch Commu. 7(1): 967-972, 2021 (January)

Intracellular invasion ability of Streptococcus agalactiae among non-invasive isolates from human adults and companion animals in Japan

ObjectiveThis study evaluated the cell invasion ability (CIA) of Streptococcus agalactiae isolates from humans and companion animals and clarified the relationship between CIA populations and their microbiological features. MethodsHuman-origin and companion animal-origin isolates were collected along with host information. We measured CIA using human-lineage colon cancer epithelium (Caco-2) and keratinocyte (HaCaT) cell lines, via virulence-associated gene profiling (bca-rib-bac-lmb-cylE-hylB-pavA-pilB-spb1-srtC1-brpA), capsular genotyping, multilocus sequence typing, and antimicrobial resistance (AMR) phenotyping/genotyping. Significant differences in data regarding CIA into epithelium and keratinocytes and those of isolates from different hosts were assessed. We analyzed the association of CIA populations with the virulence genotypes, capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes. ResultsA comparative analysis was performed between human (n = 15) and canine (n = 17) non-invasive isolates. There was a difference in CIA data between Caco-2 and HaCaT cells using human and animal isolates. For percent invasion ability into Caco-2 cells, we designated values ≥ 0.1 as high-frequency CIA and values < 0.1 as low-frequency CIA. Fourteen isolates harbored high-frequency and 18 isolates harbored low-frequency strains. There was no association between the high-frequency population and the virulence genotypes, capsular genotypes, sequence types/clonal complexes, and AMR phenotypes/genotypes. ConclusionThis is the first report assessing the invasion ability of S. agalactiae into HaCaT and Caco-2 cells. Our observations suggest that S. agalactiae is more capable of entering Caco-2 rather than HaCaT.

Population structure, genetic diversity and pathotypes of Streptococcus suis isolated during the last 13\xa0years from diseased pigs in Switzerland

Streptococcus (S.) suis is a globally important swine pathogen, which comprises certain zoonotic serotypes. In this study, a detailed characterization of 88 porcine S. suis isolates was performed by analyzing capsular (cps) types, multilocus sequence typing (MLST) and investigation of the minimum core genome (MCG). In order to focus on the virulence potential of presumable invasive disease-associated S. suis isolates, virulence-associated gene profiles were assessed followed by screening a chosen subset of S. suis strains with a molecular pathotyping tool. Results showed a high genetic variability within this strain collection. In total, seventeen cps types were identified with a predominance of cps type 9 (15.9%) and 6 (14.8%). MLST revealed 48 sequence types (STs) including 41 novel ones. The population structure of S. suis was heterogenous and isolates belonged to eight different clonal complexes (CCs) including CC28 (9.1%), CC1109 (8%), CC13/149 (6.8%), CC1237 (5.7%), CC1 (3.4%), CC17 (3.4%), CC87 (2.3%), and CC1112 (1.1%), whereas a significant portion of isolates (60.2%) could not be assigned to any described CCs. Virulence-associated markers, namely extracellular protein factor (epf), muramidase-released protein (mrp), and suilysin (sly), showed a link with STs rather than with cps types. With this study an expanded knowledge about the population structure and the genetic diversity of S. suis could be achieved, which helps to contribute to an optimal public health surveillance system by promoting a focus on strains with an increased virulence and zoonotic potential.

Whole-genome analysis of the potentially zoonotic Elizabethkingia miricola FL160902 with two new chromosomal MBL gene variants.

Elizabethkingia is an emerging life-threatening pathogen in both humans and animals. We describe the whole-genome analysis of an Elizabethkingia miricola strain isolated from a diseased frog in China and investigate the molecular mechanism of carbapenem resistance in this pathogen. WGS of E. miricola FL160902 was performed using single-molecule, real-time technology. A phylogenetic tree was generated by SNP analysis, comparing the genome of our strain with other E. miricola isolates of amphibian and human origins. Antimicrobial resistance genes and virulence-related genes were identified using the Comprehensive Antibiotic Resistance Database (CARD) and the Virulence Factor Database (VFDB). Two putative carbapenemase genes were expressed in Escherichia coli to evaluate their contribution to antimicrobial resistance. The genome of E. miricola FL160902 consists of a 4 249 586 bp circular chromosome with 27 putative resistance genes and 38 predicted virulence-associated genes. Comparative genomic analysis demonstrated that the E. miricola strains of human and amphibian origins have similar virulence-associated gene profiles. In addition, all the amphibian isolates clustered together with one of the human isolates in the phylogenetic analysis. WGS revealed the presence of two novel MBL genes, designated blaBlaB-16 and blaGOB-19. Cloning of blaBlaB-16 and blaGOB-19 into E. coli DH5α resulted in increased MICs of most β-lactams, including imipenem, meropenem and ampicillin. We identified two chromosomal MBL gene variants, named blaBlaB-16 and blaGOB-19 in an amphibian E. miricola isolate, which was considered potentially zoonotic based on phylogenetic analysis and virulence-associated gene comparison. This study highlights the importance of E. miricola as a potential zoonotic pathogen and a reservoir of MDR genes.

Whole-genome sequence-based comparison and profiling of virulence-associated genes of Bacillus cereus group isolates from diverse sources in Japan

BackgroundThe complete genome sequences of 44 Bacillus cereus group isolates collected from diverse sources in Japan were analyzed to determine their genetic backgrounds and diversity levels in Japan. Multilocus sequence typing (MLST) and core-genome single-nucleotide polymorphism (SNP) typing data from whole-genome sequences were analyzed to determine genetic diversity levels. Virulence-associated gene profiles were also used to evaluate the genetic backgrounds and relationships among the isolates.ResultsThe 44 B. cereus group isolates, including soil- and animal-derived isolates and isolates recovered from hospitalized patients and food poisoning cases, were genotyped by MLST and core-genome SNP typing. Genetic variation among the isolates was identified by the MLST and core-genome SNP phylogeny comparison against reference strains from countries outside of Japan. Exploratory principal component analysis and nonmetric multidimensional scaling (NMDS) analyses were used to assess the genetic similarities among the isolates using gene presence and absence information and isolate origins as the metadata. A significant correlation was seen between the principal components and the presence of genes encoding hemolysin BL and emetic genetic determinants in B. cereus, and the capsule proteins in B. anthracis. NMDS showed that the cluster of soil isolates overlapped with the cluster comprising animal-derived and clinical isolates.ConclusionsMolecular and epidemiological analyses of B. cereus group isolates in Japan suggest that the soil- and animal-derived bacteria from our study are not a significant risk to human health. However, because several of the clinical isolates share close genetic relationships with the environmental isolates, both molecular and epidemiological surveillance studies could be used effectively to estimate virulence in these important pathogens.

Clinical characteristics, molecular epidemiology and antimicrobial susceptibility of pertussis among children in southern China.

Increasing numbers of pertussis cases have been reported in recent years. The reported cases from Shenzhen Children's Hospital were close to one tenth of all cases in China. The epidemiology of antigenic genotype and antibiotic resistance of circulating strains in children have been unknown in Shenzhen, southern China. The aim of this study was to describe the clinical features and explore the genotypes and antimicrobial susceptibility of circulating Bordetella pertussis among children in Shenzhen. Data of hospitalized children with pertussis in Shenzhen Children's Hospital from August 2015 to April 2017 were collected. The genetic variability of isolates was investigated and Etest was performed for phenotypic susceptibility to erythromycin, azithromycin, clarithromycin, clindamycin, and trimethoprim/sulfamethoxazole. 469 children with pertussis confirmed by real-time quantitative polymerase chain reaction were hospitalized and strains were isolated from 105 patients. White blood cell count ≥ 20 × 109/L and lymphocyte proportion ≥ 60% were observed in 39.29% of infants younger than 3months. The two predominant profiles of virulence-associated allelic genes were ptxA1/ptxC1/ptxP1/prn1 (48.6%) and ptxA1/ptxC2/ptxP3/prn2 (44.8%). Among the isolates, 48.6% (51/105) were found resistant to macrolides. These findings indicate that leukocytosis is not a sensitive indicator of pertussis. Isolates with the gene profile ptxP3/prn2 were highly circulating in Shenzhen and less resistant to macrolides, different from patterns observed in other parts of China.

Virulence-Associated Gene Profiles of Avian Pathogenic Escherichia coli Isolated From Broilers With Colibacillosis: A Pilot Study in Iran

Background: Avian pathogenic Escherichia coli (APEC) causes economic losses in the chicken industry worldwide. Objective: In this study, virulence-associated gene profiles of APEC isolates were investigated by polymerase chain reaction (PCR). Materials and Methods: A total of 60 Escherichia coli isolates were collected from 60 colibacillosis cases from 30 broiler poultry farms in Alborz, Tehran, and Golestan provinces, Iran. After identification by biochemical tests, DNA was extracted by boiling method and 5 virulence-associated genes including: iutA, hlyF, iroN, ompT, and iss were detected by 2 multiplex PCR protocols. Results: Of the 60 APEC isolates, 26 (43.3%) isolates had at least three virulence genes from which 12 (20%) isolates were positive for all 5 virulence genes, whereas 34 (56.6%) carried no investigated virulence genes. Presence of iutA, hlyF, iroN, ompT, and iss genes in the APEC isolates were 17 (28.3%), 17 (28.3%), 24 (40%), 26 (43.3%), and 23 (38.3%), respectively. Conclusion: According to the results, four different virulence-associated gene profiles were seen in isolates, from which profile 1 with 12 (20%) isolates was predominant. These findings were in agreement with the previous reports.

Characterization of Klebsiella pneumoniae associated with cattle infections in southwest China using multi-locus sequence typing (MLST), antibiotic resistance and virulence-associated gene profile analysis.

Klebsiella pneumoniae is important human and animal pathogen that causes a wide spectrum of infections. In this study, isolates from cattle nasal swabs samples were identified by 16S rRNA, and to evaluate the antimicrobial susceptibility, virulence gene carrying levels, and multilocus sequence typing of K. pneumoniae isolates. 33 isolates of K. pneumoniae were isolated and identified in 213 nasal swabs samples, of which 12 were hypervirulent K. pneumoniae strains. Extended Spectrum Beta-Lactamases genes were found in 93.4% of the strains. Of which, TEM was the most prevalent (93.4%), followed by CTX-M and SHV were 57.6% and 39.4%, respectively. A main mutation pattern of quinoloneresistance-determining region, Thr83-Ieu and Asp87-Asn in gyrA and Ser87-Ile in parC, was detected in 33 K. pneumoniae isolates. All the isolates harbored at least two virulence factor genes, with ureA (97.0%) and wabG (91.0%) exhibiting high carriage rates in 33 K. pneumoniae isolates. MLST revealed 7 sequence types, of which 3 STs (2541, 2581 and 2844) were newly assigned. Using eBURST, ST2844 and ST2541 were assigned to new clonal complex 2844. Our study provides evidence and biological characteristics of K. pneumoniae isolates from cattle upper respiratory tract in Southwest China.