An AFLP-based database of Shigella flexneri and Shigella sonnei isolates and its use for the identification of untypable Shigella strains

Amplified fragment length polymorphism (AFLP) can be used to assess the genetic diversity of closely related microbial genomes. In this study, the first of its kind for identification of Shigella, the high discriminatory power of AFLP has been used to determine the genetic relatedness of 230 isolates of Shigella flexneri and Shigella sonnei strains. An AFLP database was generated to demonstrate its utility in the discrimination of closely related strains. Based on AFLP, S. flexneri strains could be grouped into separate clusters according to their serotypes. Within each serotype, strains demonstrated 80–100% similarity indicating that identical strains and closely related strains could be distinguished by this technique. S. flexneri 6 formed a distinct cluster with 55% similarity to the rest of the S. flexneri strains showing significant divergence from the rest of the S. flexneri strains. Significantly, S. sonnei isolates formed a distinct group and showed approximately the same level of genetic linkage to S. flexneri as Escherichia coli strains. Untypable isolates that showed conflicting agglutination reactions with conventional typing sera were identifiable by AFLP. Thus AFLP can be used for genetic fingerprinting of Shigella strains and aid in the identification of variant untypable isolates.     

Antimicrobial Resistance of Staphylococcus aureus Strains Acquired by Pig Farmers from Pigs

Carriage of animal-associated methicillin-resistant Staphylococcus aureus (MRSA) clonal complex 398 (CC398) is common among pig farmers. This study was conducted (i) to investigate whether pig farmers are colonized with pig-specific S. aureus genotypes other than CC398 and (ii) to survey antimicrobial resistance of S. aureus isolates from pigs and pig farmers. Forty-eight S. aureus isolates from pig farmers and veterinarians and 130 isolates from pigs collected in Western Switzerland were genotyped by spa typing and amplified fragment length polymorphism (AFLP). Antimicrobial resistance profiles were determined for representative sample of the isolates. The data obtained earlier on healthy S. aureus carriers without exposure to agriculture were used for comparison. The genotype composition of S. aureus isolates from pig farmers and veterinarians was similar to isolates from pigs with predominant AFLP clusters CC398, CC9, and CC49. The resistance to tetracycline and macrolides (clarithromycin) was common among the isolates from farmers and veterinarians (52 and 21%, respectively) and similar to resistance levels in isolates from pigs (39 and 23%, respectively). This was in contrast to isolates from persons without contact with agriculture, where no (0/128) isolates were resistant to tetracycline and 3% of the isolates were resistant to clarithromycin. MRSA CC398 was isolated from pigs (n = 11) and pig farmers (n = 5). These data imply that zoonotic transmission of multidrug-resistant S. aureus from pigs to farmers is frequent, and well-known MRSA transmission merely represents the tip of the iceberg for this phenomenon. We speculate that the relatively low frequency of MRSA isolation is related to lower antimicrobial use in Switzerland compared to, for example, the Netherlands.     

PFGE and AFLP genotyping of Staphylococcus aureus subsp. anaerobius isolated from goats with Morel’s disease

Staphylococcus aureus subsp. anaerobius is the etiological agent of the Morel’s disease in sheep and goats. The disease presents with subcutaneous abscesses, located mainly in the superficial lymph nodes. Forty-one isolates of S. aureus subsp. anaerobius were collected from two outbreaks of the Morel’s disease in Poland in years 2006–2008. Analysis of DNA SmaI digests by PFGE showed that 35 of 41 isolates belonged to the same PFGE type, identical to the type strain of S. aureus subsp. anaerobius ATCC 35844, confirming high level of clonality of the species. The DNA patterns of the remaining identical 6 isolates, different from the reference strain only by two bands, were found closely related. Genotyping performed with AFLP technique revealed two clonal groups including 16 and 25 isolates, respectively. The study indicated that AFLP technique might be a better discriminatory tool for genetic analysis of S. aureus subsp. anaerobius isolates, when compared to PFGE.     

Vancomycin-Resistant Enterococcus faecium (VREF) from Norwegian Poultry Cluster with VREF from Poultry from the United Kingdom and The Netherlands in an Amplified Fragment Length Polymorphism Genogroup

The genetic relationship between 197 vancomycin-resistant Enterococcus faecium (VREF) isolates and 21 vancomycin-susceptible E. faecium isolates from Norwegian poultry was analyzed by amplified fragment length polymorphism (AFLP). The isolates were compared to 255 VREF isolates from various sources and countries. The Norwegian isolates constituted a relatively homogeneous population of E. faecium and clustered in a previously defined poultry AFLP genogroup.     

Development of a Real-Time PCR for Identification of Brachyspira Species in Human Colonic Biopsies

Background

Brachyspira species are fastidious anaerobic microorganisms, that infect the colon of various animals. The genus contains both important pathogens of livestock as well as commensals. Two species are known to infect humans: B. aalborgi and B. pilosicoli. There is some evidence suggesting that the veterinary pathogenic B. pilosicoli is a potential zoonotic agent, however, since diagnosis in humans is based on histopathology of colon biopsies, species identification is not routinely performed in human materials.

Methods

The study population comprised 57 patients with microscopic evidence of Brachyspira infection and 26 patients with no histopathological evidence of Brachyspira infection. Concomitant faecal samples were available from three infected patients. Based on publically available 16S rDNA gene sequences of all Brachyspira species, species-specific primer sets were designed. DNA was extracted and tested by real-time PCR and 16S rDNA was sequenced.

Results

Sensitivity and specificity for identification of Brachyspira species in colon biopsies was 100% and 87.7% respectively. Sequencing revealed B. pilosicoli in 15.4% of patients, B. aalborgi in 76.9% and a third species, tentatively named “Brachyspira hominis”, in 26.2%. Ten patients (12.3%) had a double and two (3.1%) a triple infection. The presence of Brachyspira pilosicoli was significantly associated with inflammatory changes in the colon-biopsy (p = 0.028).

Conclusions

This newly designed PCR allows for sub-differentiation of Brachyspira species in patient material and thus allows large-scaled surveillance studies to elucidate the pathogenicity of human Brachyspira infections. One-third of affected patients appeared to be infected with a novel species.     

Identification and Molecular Epidemiology of Campylobacter coli Isolates from Human Gastroenteritis, Food, and Animal Sources by Amplified Fragment Length Polymorphism Analysis and Penner Serotyping

Campylobacter coli is an infrequently studied but important food-borne pathogen with a wide natural distribution. We investigated its molecular epidemiology by use of amplified fragment length polymorphism (AFLP)-based genotyping and Penner serotyping. Serotype reference strains and 177 Danish isolates of diverse origin identified by routine phenotyping as C. coli were examined. Molecular tools identified some 12% of field isolates as Campylobacter jejuni, emphasizing the need for improved identification methods in routine laboratories. Cluster analysis of AFLP profiles of 174 confirmed C. coli isolates revealed a difference in the distribution of isolates from pig and poultry (chicken, duck, turkey, and ostrich) species and indicated the various poultry species, but not pigs, to be likely sources of human C. coli infection. A poor correlation was observed between serotyping and AFLP profiling, suggesting that the former method has limited value in epidemiological studies of this species.     

Genetic variation among natural isolates of the ectomycorrhizal hypogenous fungus,Rhizopogon roseolus from Japanese pine forests inferred using AFLP markers

Genetic variation among 45 Rhizopogon roseolus isolates from 21 different regions of Japan were inferred using amplified fragment length polymorphism (AFLP) markers. Using three primer pair combinations, AFLP analysis reproducibly produced a total of 223 DNA fragments, 74.4% of which were polymorphic. Pairwise dissimilarity of AFLP patterns between isolates ranged from 0.043 to 0.228. Cluster analysis and principal coordinate analysis of AFLP data generally showed four major clusters from geographically distinct areas. The findings suggested that the Japanese populations of R. roseolus from different geographical regions can be distinguished based on AFLP characters.     

Evaluation of RAPD, ISSR and AFLP Markers for Characterization of the Loose Smut Fungus Ustilago tritici

Random Amplified Polymorphic DNA (RAPD), inter simple sequence repeat (ISSR) and Amplified Fragment Length Polymorphism (AFLP) profiling were evaluated for assessing the extent of genetic variation among the isolates of Ustilago tritici (Pers.) Rostr., which causes the loose smut disease of wheat.Thirty random decamer primers, six random primer pairs, four SSR primers such as (GACA)₄, (GATA)₄, (CAA)₅ and (GTG)₅ and nine combinations of AFLP selective primers were used to characterize nine isolates of the fungus. These isolates were collected from infected earheads of seven commercial wheat cultivars grown at eight different locations in Haryana, which is a major wheat growing state in the North-West Plain Zone of India. The RAPD and ISSR primers generated 21 0 scorable amplified fragments, all of which were monomorphic among the isolates.The AFLP primer combinations generated 239 fragments out of which 193 were polymorphic. All the isolates could be precisely differentiated from each other employing AFLP and grouped into two distinct clusters.The molecular classification partly corresponded with geographic distribution and host origin of the isolates. AFLP profiling was found superior to RAPD and ISSR and can be effectively utilized for further characterization of loose smut pathogen.     

Genetic Diversity and Ecological Success of Staphylococcus aureus Strains Colonizing Humans

The genetic determinants and phenotypic traits which make a Staphylococcus aureus strain a successful colonizer are largely unknown. The genetic diversity and population structure of 133 S. aureus isolates from healthy, generally risk-free adult carriers were investigated using four different typing methods: multilocus sequence typing (MLST), amplified fragment length polymorphism analysis (AFLP), double-locus sequence typing (DLST), and spa typing were compared. Carriage isolates displayed great genetic diversity which could only be revealed fully by DLST. Results of AFLP and MLST were highly concordant in the delineation of genotypic clusters of closely related isolates, roughly equivalent to clonal complexes. spa typing and DLST provided considerably less phylogenetic information. The resolution of spa typing was similar to that of AFLP and inferior to that of DLST. AFLP proved to be the most universal method, combining a phylogeny-building capacity similar to that of MLST with a much higher resolution. However, it had a lower reproducibility than sequencing-based MLST, DLST, and spa typing. We found two cases of methicillin-resistant S. aureus colonization, both of which were most likely associated with employment at a health service. Of 21 genotypic clusters detected, 2 were most prevalent: cluster 45 and cluster 30 each colonized 24% of the carrier population. The number of bacteria found in nasal samples varied significantly among the clusters, but the most prevalent clusters were not particularly numerous in the nasal samples. We did not find much evidence that genotypic clusters were associated with different carrier characteristics, such as age, sex, medical conditions, or antibiotic use. This may provide empirical support for the idea that genetic clusters in bacteria are maintained in the absence of adaptation to different niches. Alternatively, carrier characteristics other than those evaluated here or factors other than human hosts may exert selective pressure maintaining genotypic clusters.     

The Complete Genome Sequence of the Pathogenic Intestinal Spirochete Brachyspira pilosicoli and Comparison with Other Brachyspira Genomes

Background

The anaerobic spirochete Brachyspira pilosicoli colonizes the large intestine of various species of birds and mammals, including humans. It causes “intestinal spirochetosis”, a condition characterized by mild colitis, diarrhea and reduced growth. This study aimed to sequence and analyse the bacterial genome to investigate the genetic basis of its specialized ecology and virulence.

Methodology/Principal Findings

The genome of B. pilosicoli 95/1000 was sequenced, assembled and compared with that of the pathogenic Brachyspira hyodysenteriae and a near-complete sequence of Brachyspira murdochii. The B. pilosicoli genome was circular, composed of 2,586,443 bp with a 27.9 mol% G+C content, and encoded 2,338 genes. The three Brachyspira species shared 1,087 genes and showed evidence of extensive genome rearrangements. Despite minor differences in predicted protein functional groups, the species had many similar features including core metabolic pathways. Genes distinguishing B. pilosicoli from B. hyodysenteriae included those for a previously undescribed bacteriophage that may be useful for genetic manipulation, for a glycine reductase complex allowing use of glycine whilst protecting from oxidative stress, and for aconitase and related enzymes in the incomplete TCA cycle, allowing glutamate synthesis and function of the cycle during oxidative stress. B. pilosicoli had substantially fewer methyl-accepting chemotaxis genes than B. hyodysenteriae and hence these species are likely to have different chemotactic responses that may help to explain their different host range and colonization sites. B. pilosicoli lacked the gene for a new putative hemolysin identified in B. hyodysenteriae WA1. Both B. pilosicoli and B. murdochii lacked the rfbBADC gene cluster found on the B. hyodysenteriae plasmid, and hence were predicted to have different lipooligosaccharide structures. Overall, B. pilosicoli 95/1000 had a variety of genes potentially contributing to virulence.

Conclusions/Significance

The availability of the complete genome sequence of B. pilosicoli 95/1000 will facilitate functional genomics studies aimed at elucidating host-pathogen interactions and virulence.     

The Widespread Presence of a Multidrug-Resistant Escherichia coli ST131 Clade among Community-Associated and Hospitalized Patients

Background & Aims

The extent of entry of multidrug-resistant Escherichia coli from the community into the hospital and subsequent clonal spread amongst patients is unclear. To investigate the extent and direction of clonal spread of these bacteria within a large teaching hospital, we prospectively genotyped multidrug-resistant E. coli obtained from community- and hospital associated patient groups and compared the distribution of diverse genetic markers.

Methods

A total of 222 E. coli, classified as multi-drug resistant according to national guidelines, were retrieved from both screening (n = 184) and non-screening clinical cultures (n = 38) from outpatients and patients hospitalized for various periods. All isolates were routinely genotyped using an amplified fragment length polymorphism (AFLP) assay and real-time PCR for CTX-M genes. Multi-locus sequence typing was additionally performed to confirm clusters. Based on demographics, patients were categorized into two groups: patients that were not hospitalized or less than 72 hours at time of strain isolation (group I) and patients that were hospitalized for at least 72 hours (group II).

Results

Genotyping showed that most multi-drug resistant E. coli either had unique AFLP profiles or grouped in small clusters of maximally 8 isolates. We identified one large ST131 clade comprising 31% of all isolates, containing several AFLP clusters with similar profiles. Although different AFLP clusters were found in the two patient groups, overall genetic heterogeneity was similar (35% vs 28% of isolates containing unique AFLP profiles, respectively). In addition, similar distributions of CTX-M groups, including CTX-M 15 (40% and 44% of isolates in group I and II, respectively) and ST131 (32% and 30% of isolates, respectively) were found.

Conclusion

We conclude that multi-drug resistant E. coli from the CTX-M 15 associated lineage ST131 are widespread amongst both community- and hospital associated patient groups, with similar genetic diversity and similar distributions of genetic markers.     

Binary IS typing for Staphylococcus aureus

Background

We present an easily applicable test for rapid binary typing of Staphylococcus aureus: binary interspace (IS) typing. This test is a further development of a previously described molecular typing technique that is based on length polymorphisms of the 16S-23S rDNA interspace region of S. aureus.

Methodology/Principal Findings

A novel approach of IS-typing was performed in which binary profiles are created. 424 human and animal derived MRSA and MSSA isolates were tested and a subset of these isolates was compared with multi locus sequence typing (MLST) and Amplified Fragment Length Polymorphism (AFLP). Binary IS typing had a high discriminatory potential and a good correlation with MLST and AFLP.

Conclusions/Significance

Binary IS typing is easy to perform and binary profiles can be generated in a standardized fashion. These two features, combined with the high correlation with MLST clonal complexes, make the technique applicable for large-scale inter-laboratory molecular epidemiological comparisons.     

Fluorescent Amplified Fragment Length Polymorphism Analysis of Bacillus anthracis, Bacillus cereus, and Bacillus thuringiensis Isolates

DNA from over 300 Bacillus thuringiensis, Bacillus cereus, and Bacillus anthracis isolates was analyzed by fluorescent amplified fragment length polymorphism (AFLP). B. thuringiensis and B. cereus isolates were from diverse sources and locations, including soil, clinical isolates and food products causing diarrheal and emetic outbreaks, and type strains from the American Type Culture Collection, and over 200 B. thuringiensis isolates representing 36 serovars or subspecies were from the U.S. Department of Agriculture collection. Twenty-four diverse B. anthracis isolates were also included. Phylogenetic analysis of AFLP data revealed extensive diversity within B. thuringiensis and B. cereus compared to the monomorphic nature of B. anthracis. All of the B. anthracis strains were more closely related to each other than to any other Bacillus isolate, while B. cereus and B. thuringiensis strains populated the entire tree. Ten distinct branches were defined, with many branches containing both B. cereus and B. thuringiensis isolates. A single branch contained all the B. anthracis isolates plus an unusual B. thuringiensis isolate that is pathogenic in mice. In contrast, B. thuringiensis subsp. kurstaki (ATCC 33679) and other isolates used to prepare insecticides mapped distal to the B. anthracis isolates. The interspersion of B. cereus and B. thuringiensis isolates within the phylogenetic tree suggests that phenotypic traits used to distinguish between these two species do not reflect the genomic content of the different isolates and that horizontal gene transfer plays an important role in establishing the phenotype of each of these microbes. B. thuringiensis isolates of a particular subspecies tended to cluster together.     

Molecular diversity and allergenic profiles of Alternaria spp. from desert environments in Arizona

This study examined the genetic diversity of small-spored Alternaria species in the southwest desert of the USA by sampling 552 isolates from different habitats (soil and plant debris) in different locations (urban and an undisturbed desert). To estimate the genetic diversity, Amplified Fragment Length Polymorphism (AFLP) fingerprinting analysis was performed for all isolates. Strains representative of the sampled genotypic diversity (n = 125) were further characterized according their sporulation pattern and the capability to produce allergens. Morphological characterization assigned the majority of the strains to the Alternaria alternata and Alternaria tenuissima morpho-groups with only two isolates assigned to the Alternaria arborescens morpho-group. AFLP fingerprinting differentiated the A. arborescens morpho-groups, but could not distinguish between the A. alternata and A. tenuissima morpho-groups. Western blot analysis showed that a large number of allergenic proteins were produced by strains. These proteins were not specific for any morpho-group nor source of isolation. A hierarchical analysis of molecular variance was performed on the AFLP data to quantify molecular variation and partition this variation among sampled locations and habitat. No statistically significant differentiation among locations and habitat was detected indicating a lack of population structure across environments.     

Fluorescent Amplified Fragment Length Polymorphism Analysis of Norwegian Bacillus cereus and Bacillus thuringiensis Soil Isolates

We examined 154 Norwegian B. cereus and B. thuringiensis soil isolates (collected from five different locations), 8 B. cereus and 2 B. thuringiensis reference strains, and 2 Bacillus anthracis strains by using fluorescent amplified fragment length polymorphism (AFLP). We employed a novel fragment identification approach based on a hierarchical agglomerative clustering routine that identifies fragments in an automated fashion. No method is free of error, and we identified the major sources so that experiments can be designed to minimize its effect. Phylogenetic analysis of the fluorescent AFLP results reveals five genetic groups in these group 1 bacilli. The ATCC reference strains were restricted to two of the genetic groups, clearly not representative of the diversity in these bacteria. Both B. anthracis strains analyzed were closely related and affiliated with a B. cereus milk isolate (ATCC 4342) and a B. cereus human pathogenic strain (periodontitis). Across the entire study, pathogenic strains, including B. anthracis, were more closely related to one another than to the environmental isolates. Eight strains representing the five distinct phylogenetic clusters were further analyzed by comparison of their 16S rRNA gene sequences to confirm the phylogenetic status of these groups. This analysis was consistent with the AFLP analysis, although of much lower resolution. The innovation of automated genotype analysis by using a replicated and statistical approach to fragment identification will allow very large sample analyses in the future.     

Analysis of genetic diversity in Phytophthora colocasiae causing leaf blight of taro (Colocasia esculenta) using AFLP and RAPD markers

The oomycetous fungus Phytophthora colocasiae that causes taro leaf blight is one of the most devastating diseases of taro and is widely distributed in India. Molecular and cultural techniques were employed for assessing and exploiting the genetic variability among isolates of P. colocasiae obtained from different geographical regions of India. Analysis of the 5.8-ITS region revealed detectable intraspecific variation among isolates. Ten random amplified polymorphic DNA (RAPD) and eight amplified fragment length polymorphism (AFLP) primers produced 198 and 510 reproducible fragments, respectively. AFLP produced 100 % polymorphism, whereas RAPD showed 93.5 % polymorphism. The average value of the number of observed alleles, the number of effective alleles, mean Nei’s genetic diversity, and Shannon’s information index were 2.00–1.94, 1.53–1.36, 0.31–0.24, and 0.47–0.40, respectively, for two DNA markers used. Analysis of molecular variance (AMOVA) for both markers produced similar results with the majority (85 %, AFLP; 89 %, RAPD) of the diversity present within population of P. colocasiae. Dendrograms based on two molecular data using the unweighted pair group method with arithmetic mean (UPGMA) was incongruent and classified the P. colocasiae isolates into one and two major clusters. Cophenetic correlation coefficient between dendrogram and original similarity matrix were significant for RAPD (r?=?0.904) and AFLP (r?=?0.825). The results of this study displayed a high level of genetic variation among the isolates irrespective of the geographical origin. The possible mechanisms and implications of this genetic variation are discussed.     

Photobacterium piscicola sp. nov., isolated from marine fish and spoiled packed cod

Five isolates from marine fish (W3^T, WM, W1S, S2 and S3) and three isolates misclassified as Photobacterium phosphoreum, originating from spoiled modified atmosphere packed stored cod (NCIMB 13482 and NCIMB 13483) and the intestine of skate (NCIMB 192), were subjected to a polyphasic taxonomic study. Phylogenetic analysis of 16S rRNA gene sequences showed that the isolates were members of the genus Photobacterium. Sequence analysis using the gapA, gyrB, pyrH, recA and rpoA loci showed that these isolates formed a distinct branch in the genus Photobacterium, and were most closely related to Photobacterium aquimaris, Photobacterium kishitanii, Photobacterium phosphoreum and Photobacterium iliopiscarium. The luxA gene was present in isolates W3^T, WM, W1S, S2 and S3 but not in NCIMB 13482, NCIMB 13483 and NCIMB 192. AFLP and (GTG)₅-PCR fingerprinting indicated that the eight isolates represented at least five distinct genotypes. DNA–DNA hybridizations revealed 89% relatedness between isolate W3^T and NCIMB 192, and values below 70% with the type strains of the phylogenetically closest species, P. iliopiscarium LMG 19543^T, P. kishitanii LMG 23890^T, P. aquimaris LMG 26951^T and P. phosphoreum LMG4233^T. The strains of this new taxon could also be distinguished from the latter species by phenotypic characteristics. Therefore, we propose to classify this new taxon as Photobacterium piscicola sp. nov., with W3^T (=NCCB 100098^T = LMG 27681^T) as the type strain.     

Molecular characterization, morphology, and pathogenicity of Alternaria panax from araliaceous plants in Korea

Alternaria blight on araliaceous plants is a common disease caused by Alternaria panax Whetzel and occurs worldwide. Genetic diversity among 58 isolates of A. panax from different araliaceous hosts in Korea was determined by amplified fragment length polymorphism (AFLP) analysis. Selected isolates from genetic groups (determined by AFLP analysis) were examined based on the results of phylogenetic analyses of eight genes (Alt a1, BT1, BT2, EF-1α, gpd, H3, ITS, and RPB2), morphological characteristics, and pathogenicity tests. Isolates were divided into two distinct genetic groups (A and B) by AFLP analysis and based on the results of sequence analyses of the BT1, BT2, gpd, and RPB2 genes. Isolates from ginseng plants (Panax ginseng and P. quinquefolius) fell into group B, whereas isolates from the other araliaceous plants clustered in group A. Morphologically, although some overlap was observed among isolates in the two groups, isolates in group B had longer and narrower conidia, distinct sporulation patterns at 15 °C, and did not secrete pigment into PDA media. Pathogenicity tests revealed that isolates in groups A and B only induced severe disease symptoms on leaves of their hosts, such as isolates in group A on Aralia elata, Aralia continentalis, and in group B on Panax ginseng. The results indicate that the two genetic groups of Alternaria from araliaceous plants should be considered as two different species, and we propose that group A is a candidate of new Alternaria species distinguished from A. panax.     

Genomic Relatedness within Five Common Finnish Campylobacter jejuni Pulsed-Field Gel Electrophoresis Genotypes Studied by Amplified Fragment Length Polymorphism Analysis, Ribotyping, and Serotyping

Thirty-five Finnish Campylobacter jejuni strains with five SmaI/SacII pulsed-field gel electrophoresis (PFGE) genotypes selected among human and chicken isolates from 1997 and 1998 were used for comparison of their PFGE patterns, amplified fragment length polymorphism (AFLP) patterns, HaeIII ribotypes, and heat-stable (HS) serotypes. The discriminatory power of PFGE, AFLP, and ribotyping with HaeIII were shown to be at the same level for this selected set of strains, and these methods assigned the strains into the same groups. The PFGE and AFLP patterns within a genotype were highly similar, indicating genetic relatedness. The same HS serotypes were distributed among different genotypes, and different serotypes were identified within one genotype. HS serotype 12 was only associated with the combined genotype G1 (PFGE-AFLP-ribotype). These studies using polyphasic genotyping methods suggested that common Finnish C. jejuni genotypes form genetic lineages which colonize both humans and chickens.