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Results for “Multilocus Sequence Typing”

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PubMed2006

Australian multicentre comparison of subtyping methods for the investigation of Campylobacter infection.

In order to identify subtyping methods able to contribute to the surveillance or investigation of Australian Campylobacter infection, six genotypic and three phenotypic subtyping methods were evaluated on a collection of 84 clinical isolates collected over a 30-month period from one region in Australia. The aim was to compare the logistics of various subtyping methods and examine their ability to assist in finding outbreaks or common sources of sporadic infection. The genotypic subtyping methods used were sequencing of the short variable region of the flaA gene, two methods using restriction fragment length polymorphism (RFLP) of the flaA gene using either DdeI or EcoRI with PstI, automated ribotyping, pulsed field gel electrophoresis and multilocus sequence typing. The phenotypic methods employed included Laboratory of Enteric Pathogens serotyping, Lior biotyping and antibiotic resistotyping. The level of agreement between subtyping results was determined. Phenotypic methods showed little agreement whereas genotypic typing methods showed a high level of agreement. Using the premise that five of the six genotypic typing methods were in agreement 15 genotypic groupings were identified. Sequencing of the short variable region of the flaA gene, RFLP of the flaA gene or automated ribotyping in conjunction with multilocus sequence typing best identified genotypic groupings. An alternative combination of RFLP of the flaA gene followed by ribotyping was equally satisfactory. RFLP of the flaA gene appeared to be suitable as a preliminary typing method based on ease of operation, equipment availability and cost.

Australia↗

PubMed2005

Molecular epidemiology of macrolide-resistant Streptococcus pneumoniae isolates in Europe.

In many European countries, the level of pneumococcal resistance to macrolides has now passed the level of resistance to penicillin G. A total of 82 erythromycin A-resistant isolates of Streptococcus pneumoniae were collected by 11 laboratories in seven European countries. All of the isolates were tested for antimicrobial susceptibility, analyzed for clonal relatedness by multilocus sequence typing, and characterized for macrolide resistance genotypes. The prevalence of the macrolide resistance genotypes varied substantially between countries. In France (87.5% of all strains), Spain (77.3%), Switzerland (80%), and Poland (100%), strains were predominantly erm(B) positive, whereas higher levels of mef(A)-positive strains were reported from Greece (100%) and Germany (33.3%). Macrolide resistance was caused by the oligoclonal spread of some multilocus sequence types, but significant differences in clonal distribution were noted between France and Spain, countries from which high levels of macrolide resistance have been reported. Overall, sequence type 81 (Spain23F-1 clone) was by far the most widespread. The mainly erm(B)-positive serotype 14 clone (sequence type 143), first reported in Poland in the mid-1990s, is now widespread in France.

Bacterial Typing Techniques↗

PubMed2004

Binding and agglutination of Streptococcus pneumoniae by human surfactant protein D (SP-D) vary between strains, but SP-D fails to enhance killing by neutrophils.

Recombinant human surfactant protein D (SP-D) expressed in Escherichia coli, consisting of the head and neck regions of the native molecule, bound to all strains of Streptococcus pneumoniae that were tested, but the extent of binding varied between strains of differing capsular serotypes. The recombinant protein expressed in the yeast Pichia pastoris did not bind. Full-length native SP-D aggregated pneumococci in a calcium-dependent manner that was inhibited by maltose acting as a competitive sugar. The ability of SP-D to modulate the uptake and killing of pneumococci by human neutrophils was also addressed. Neither recombinant truncated SP-D nor native full-length SP-D enhanced the killing of pneumococci by human neutrophils. Aggregation of pneumococci varied not only between strains of the same multilocus sequence type and different serotypes but also between strains of the same serotype. However, use of recombinant strains in which the serotype had been changed showed that the degree of aggregation was influenced by the capsular type. Indeed, a 19F serotype strain which was not aggregated by SP-D did exhibit aggregation when the original isogenic strain was capsule switched to capsular serotype 3. However, although our results show that SP-D is capable of aggregating most pneumococci, no correlation between the degree of aggregation and the capsule or multilocus sequence type of the pneumococcus was clearly apparent. Therefore, although the capsule serotype is not the only determinant of aggregation by SP-D, the data presented here indicate that it does have a role to play.

Agglutination↗

PubMed2004

Exploring the concept of clonality in bacteria.

Isolates of bacterial species that are indistinguishable in genotype are assigned as a clone, with the implication that they are descended from the same recent ancestor. Clones are difficult to define with precision since bacteria are not truly asexual, and recombinational replacements result in diversification of the ancestral genotype of a clone, to produce a cluster of increasingly diverse genotypes (a clonal complex). The rate at which clonal diversification occurs depends on the extent of recombination, which varies among bacteria, so that some species have rather stable clones (e.g., Salmonella enterica), whereas in other species (e.g., Helicobacter pylori) clones may be so transient that they cannot readily be discerned. Clones and clonal complexes need to be assigned by indexing genetic variation that is selectively neutral, and currently this is best achieved using multilocus sequence typing. Some species of bacterial pathogens are very diverse, whereas others are genetically uniform, and some are, in essence, a single clone of a mother species that has been raised to species status due to the distinctiveness of the disease it causes (e.g., Yersinia pestis, Salmonella typhi, or Burkholderia mallei). The population structures of bacteria depend on the rate of recombination, and comparative measures of the extent of recombination during clonal diversification can be obtained from multilocus sequence typing data, as can measures of the longer-term impact of recombination. These studies show a wide range of recombination rates among bacterial species, and indicate that recombination in many bacteria has been sufficiently extensive that a reliable evolutionary history of the species cannot be inferred.

Bacteria↗

PubMed2003

An outbreak of conjunctivitis due to atypical Streptococcus pneumoniae.

BACKGROUND: In February 2002, clinicians at the Dartmouth College Health Service recognized an outbreak of conjunctivitis; cultures of conjunctival swabs implicated Streptococcus pneumoniae. An investigation was begun to determine the extent of the outbreak, confirm the cause, identify modes of transmission, and implement control measures. METHODS: Investigators reviewed the health service's data base for diagnoses of conjunctivitis. Viral and bacterial cultures were obtained from ill students. Bile-soluble isolates that were susceptible to ethylhydrocupreine (optochin) and therefore were presumed to be pneumococci underwent serotyping, capsular staining, pulsed-field gel electrophoresis, a DNA probe, and multilocus sequence typing. A cohort study of risk factors was conducted with the use of the Internet. Control measures included distribution of alcohol-based hand gel and messages about prevention. RESULTS: Among 5060 students, 698 (13.8 percent) received a diagnosis of conjunctivitis from January 1, 2002, through April 12, 2002, including 22 percent of first-year students. Presumed pneumococci were isolated from 43.3 percent of conjunctival swabs (110 of 254); viral cultures performed on 85 specimens were negative. DNA probes and multilocus sequence typing confirmed that the organisms were pneumococci, although the bacteria did not have the characteristic capsule. On pulsed-field gel electrophoresis, strains were found to be identical to pneumococci that caused outbreaks of conjunctivitis in other parts of the country in 1980. Analysis of survey data from 1832 students indicated that close contact with a student with conjunctivitis, wearing contact lenses, membership on a sports team, and attending parties at or living in a fraternity or sorority house were associated with conjunctivitis. The rate of diagnosis of conjunctivitis declined after the implementation of control measures and after spring break. CONCLUSIONS: This large outbreak of conjunctivitis on a college campus was caused by an atypical, unencapsulated strain of S. pneumoniae that was identical to strains that had caused outbreaks two decades earlier.

Conjunctiva↗

PubMed2004

A rapid increase in macrolide resistance in Streptococcus pyogenes isolated in Poland during 1996-2002.

OBJECTIVES: The aim of this study was to investigate Polish clinical isolates of Streptococcus pyogenes collected during a 7 year period using phenotypic and genotypic techniques. METHODS: A total of 816 isolates of S. pyogenes recovered from 33 medical centres in Poland were tested for their susceptibility to various antimicrobial agents. Erythromycin-resistant isolates were analysed by PFGE, multilocus sequence typing and emm typing methods. RESULTS: The tetracycline resistance rate was high (43%) among all S. pyogenes strains. Ninety-eight (12%) isolates were resistant to erythromycin. A low prevalence of the M phenotype (5.1%) associated with the presence of the mef(A) gene was found. All the isolates of the iMLSB phenotype harboured the erm(TR) gene. Out of the cMLSB isolates, 71.4% and 28.6% carried erm(TR) and erm(B), respectively. All isolates with erm(B) were resistant to telithromycin. PFGE analysis discerned 13 different patterns, A-N, with two predominant PFGE profiles--A (41 isolates) and B (25 isolates)--that in multilocus sequence typing corresponded, respectively, to a novel sequence type (ST) 367 and ST63. Overall, the representatives of these clones accounted for >90% of isolates of the iMLSB phenotype. CONCLUSIONS: A significant increase in erythromycin resistance was observed among clinical S. pyogenes collected in Poland over a 7 year period driven by the spread of two epidemic clones.

Anti-Bacterial Agents↗

PubMed2005

Spatial epidemiology and natural population structure of Campylobacter jejuni colonizing a farmland ecosystem.

Recent progress in determining the population structure of Campylobacter jejuni, and discerning associations between genotypes and specific niches, has emphasized the shortfall in our understanding of the ecology and epidemiology of this bacterium. We examined the natural structure of the C. jejuni community associated with cattle farmland in the UK by structured spatiotemporal sampling of habitats, including livestock and wild animal faeces, environmental water and soil, over a 10-week period within a 100 km2 area. A total of 172 isolates were characterized using multilocus sequence typing into 65 sequence types (STs). Isolates from cattle faeces were significantly over-represented in the ST-61 complex, whereas isolates from wildlife faeces and water were more likely to belong to the ST-45 complex and a number of unusual STs, many of which were first encountered during this study. Sampling within a narrow spatiotemporal window permitted the application of novel statistical methods exploring the relationship between the genetic relatedness and spatial separation of isolates. This approach showed that isolates from the same sampling squares and squares separated by <1.0 km were genetically more similar than isolates separated by greater distances. Our study demonstrates the potential of multilocus sequence typing combined with spatial modelling in exploring natural transmission pathways for C. jejuni.

Agriculture↗

PubMed2004

Culture-negative endocarditis due to Houston Complex Bartonella henselae acquired in Noumea, New Caledonia.

A 44-year-old man with a bioprosthetic aortic valve suffered destructive endocarditis with severe embolic disease due to Bartonella henselae infection. Multilocus sequence typing was successfully performed with crude preparations of operative tissue as templates, and the infecting organism was determined to be typical of the Houston clonal group, although it was never cultured from blood or tissue. This is the first report of B. henselae infection in the South Pacific, and it reminds one that B. henselae is a cause of potentially lethal culture-negative endocarditis which may respond poorly to conventional empirical therapy. Nothing is known of the epidemiology of the infection in this region, but it is likely to be common and to contain representatives of both major clonal complexes. This study emphasizes the ease with which multilocus sequence typing can be used directly with tissue, which is important because of suggestions of strain-dependent clinical outcomes.

Angiomatosis, Bacillary↗

PubMed2005

Phenotypic and genotypic discrepancy of Streptococcus pneumoniae strains isolated from Asian countries.

Non-typeable isolates of Streptococcus pneumoniae collected from Asian countries were characterized by optochin susceptibility test, bile solubility test, multilocus sequence typing of housekeeping genes, amplification of virulence-related genes, 16S rDNA-RsaI digestion, and 16S rDNA sequencing. Six of 54 non-typeable pneumococcal isolates showed divergence of gene sequences of recP and xpt from typical pneumococcal strains. Of these six atypical pneumococcal strains, two showed different results in optochin susceptibility or bile solubility test from typical pneumococcal strains. All six isolates showed high sequence dissimilarities of multilocus sequence typing, 16S rDNA sequences, and lytA sequences from typical S. pneumoniae strains. Data from this study suggest that classic tests such as optochin susceptibility and bile solubility tests may lead to incorrect identification of S. pneumoniae. These atypical strains may belong to different bacterial species from S. pneumoniae.

Anti-Bacterial Agents↗

PubMed2006

Streptococcus pneumoniae serogroups 15 and 33: an increasing cause of pneumococcal infections in children in the United States after the introduction of the pneumococcal 7-valent conjugate vaccine.

BACKGROUND: After the widespread use of the 7-valent pneumococcal conjugate vaccine, replacement serotypes have emerged. Serogroups 15 and 33 have emerged as nonvaccine serotypes causing invasive disease. We describe the clinical characteristics of children with infections caused by these serogroups and determined the genetic relationship of the strains. MATERIALS AND METHODS: The United States Pediatric Multicenter Pneumococcal Surveillance Group has prospectively identified children with pneumococcal infections since 1993. Charts were reviewed retrospectively, isolates were serogrouped and serotyped and randomly selected strains were fingerprinted with the use of pulsed field gel electrophoresis. Selected strains were further characterized by multilocus sequence typing. RESULTS: Between January 1994 and December 2004, 103 children had pneumococcal disease caused by serogroup 15, and 40 children had infections caused by serogroup 33. There was an increase from a mean of 7 cases per year for serogroup 15 in the prevaccine period to 14 cases per year in the postvaccine period and from 2 cases per year for serogroup 33 to 7 cases per year in the same periods. Isolates were susceptible to penicillin and ceftriaxone in both periods. A predominant clone was found in each serogroup representing 60% (30 of 50) of serogroup 15 strains and 83% (24 of 29) of the serotype 33F strains. The serogroup 15 clone comprised strains of serotypes 15B and 15C, whereas the 33 clone contained only serotype 33F strains. One isolate from each of the 15 and 33 clones was characterized by multilocus sequence typing and were found to be ST199 and 100, respectively. CONCLUSIONS: Pneumococcal disease in children caused by penicillin-susceptible clones of serogroups 15 and 33 is increasing in the United States. Clinicians should consider replacement serotypes when encountered with invasive pneumococcal disease in vaccinated children.

Adolescent↗

PubMed2001

Annotated draft genomic sequence from a Streptococcus pneumoniae type 19F clinical isolate.

The public availability of numerous microbial genomes is enabling the analysis of bacterial biology in great detail and with an unprecedented, organism-wide and taxon-wide, broad scope. Streptococcus pneumoniae is one of the most important bacterial pathogens throughout the world. We present here sequences and functional annotations for 2.1-Mbp of pneumococcal DNA, covering more than 90% of the total estimated size of the genome. The sequenced strain is a clinical isolate resistant to macrolides and tetracycline. It carries a type 19F capsular locus, but multilocus sequence typing for several conserved genetic loci suggests that the strain sequenced belongs to a pneumococcal lineage that most often expresses a serotype 15 capsular polysaccharide. A total of 2,046 putative open reading frames (ORFs) longer than 100 amino acids were identified (average of 1,009 bp per ORF), including all described two-component systems and aminoacyl tRNA synthetases. Comparisons to other complete, or nearly complete, bacterial genomes were made and are presented in a graphical form for all the predicted proteins.

DNA, Bacterial↗

PubMed2006

Microbial ecology in the age of genomics and metagenomics: concepts, tools, and recent advances.

Microbial ecology examines the diversity and activity of micro-organisms in Earth's biosphere. In the last 20 years, the application of genomics tools have revolutionized microbial ecological studies and drastically expanded our view on the previously underappreciated microbial world. This review first introduces the basic concepts in microbial ecology and the main genomics methods that have been used to examine natural microbial populations and communities. In the ensuing three specific sections, the applications of the genomics in microbial ecological research are highlighted. The first describes the widespread application of multilocus sequence typing and representational difference analysis in studying genetic variation within microbial species. Such investigations have identified that migration, horizontal gene transfer and recombination are common in natural microbial populations and that microbial strains can be highly variable in genome size and gene content. The second section highlights and summarizes the use of four specific genomics methods (phylogenetic analysis of ribosomal RNA, DNA-DNA re-association kinetics, metagenomics, and micro-arrays) in analysing the diversity and potential activity of microbial populations and communities from a variety of terrestrial and aquatic environments. Such analyses have identified many unexpected phylogenetic lineages in viruses, bacteria, archaea, and microbial eukaryotes. Functional analyses of environmental DNA also revealed highly prevalent, but previously unknown, metabolic processes in natural microbial communities. In the third section, the ecological implications of sequenced microbial genomes are briefly discussed. Comparative analyses of prokaryotic genomic sequences suggest the importance of ecology in determining microbial genome size and gene content. The significant variability in genome size and gene content among strains and species of prokaryotes indicate the highly fluid nature of prokaryotic genomes, a result consistent with those from multilocus sequence typing and representational difference analyses. The integration of various levels of ecological analyses coupled to the application and further development of high throughput technologies are accelerating the pace of discovery in microbial ecology.

DNA, Ribosomal↗

PubMed2004

Delineation of the endemic and sporadic methicillin-resistant Staphylococcus aureus clones in a Czech hospital.

The aim of this study was to define the endemic clones of methicillin-resistant Staphylococcus aureus (MRSA) among strains collected between September, 2001, and February, 2003, at the regional hospital of Nový Jicín, Czech Republic. The isolates were characterized by susceptibility tests, HindIII ribotyping, and pulsed-field gel electrophoresis. Representatives of each clonal type were analyzed by multilocus sequence typing and staphylococcal cassette chromosome mec (SCCmec) typing. The prevalence of the most important macrolide (ermA, ermB, ermC, and msrA) and aminoglycoside (aac6'-aph2", aph3', and ant4') resistance genes was evaluated as well. Our results document the existence of two international MRSA clones: (1) the Iberian clone (ST247:SCCmec IA:PFGE A:ribotype H2), endemic in the hospital and associated to a single multiresistant phenotype; and (2) clone EMRSA-15 (ST22:SCCmec IV:PFGE H-ribotype H7), appearing in the beginning of 2002 and associated with three phenotypes. These two clones could be distinguished by antibiogram, distribution of macrolide and aminoglycoside resistance genes (ermA, aac6'-aph2", ant4' versus ermC and msrA in a few isolates), production of beta-lactamase, and presence of enterotoxin A (in the Iberian clone).

Czech Republic↗

PubMed2003

Update on the major clonal types of methicillin-resistant Staphylococcus aureus in the Czech Republic.

The purpose of our study was the molecular characterization of methicillin-resistant Staphylococcus aureus (MRSA) strains isolated in 21 hospitals in the Czech Republic in the period 2000-2002 and comparison with previous results from 1996-1997. Strains were analyzed by pulsed-field gel electrophoresis (PFGE) of SmaI digests and ribotyping of HindIII digests hybridized with a 16S-23S DNA probe. The prevalence of the most clinically important macrolide (ermA, ermB, ermC, and msrA) and aminoglycoside (aph3', ant4', and aac6'-aph2") resistance genes was evaluated as well. Selected isolates representative of each clonal type were analyzed by multilocus sequence typing and by a multiplex PCR method capable of identifying the structural type of the staphylococcal cassette chromosome mec (SCCmec) carried by the bacteria. Our results document the displacement of the Brazilian clone (ST239, SCCmec type IIIA, PFGE type B, ribotype H1) by a new clone that we named "Czech clone" (ST239, SCCmec type IIIA, PFGE type F, ribotype H6) and the maintenance of the Iberian clone (ST247, SCCmec type IA, PFGE type A, ribotype H2) exclusively in one hospital in the Czech Republic. In addition, we found a correlation between the distribution of aminoglycoside resistance genes and MRSA clonal types.

Czech Republic↗

PubMed2004

Tracking methicillin-resistant Staphylococcus aureus clones during a 5-year period (1998 to 2002) in a Spanish hospital.

Three hundred seventy-five consecutive methicillin-resistant Staphylococcus aureus (MRSA) clinical isolates recovered between 1998 and 2002 at the Nuestra Señora de Candelaria University Hospital in Tenerife, Spain, were analyzed by molecular fingerprinting techniques to determine MRSA clonal types and their prevalence over time. After determining antibiotic susceptibility, we used SmaI-digested genomic DNA separated by pulsed-field gel electrophoresis (PFGE) to characterize MRSA isolates and to establish PFGE types. Additionally, several selected isolates representative of each major PFGE type were tested by multilocus sequence typing (MLST) and by a multiplex PCR method capable of identifying the structural type of the staphylococcal cassette chromosome mec (SCCmec), generating the corresponding sequence type (ST)-SCCmec types. Results of PFGE, supported by those of MLST and SCCmec typing, allowed us to identify six MRSA clones within the five major PFGE types and document temporal shifts in the prevalence of these MRSA clones from 1998 to 2002. Four of the clones were the pandemic "Iberian" (designated ST247-MRSA-IA), EMRSA-15 (ST22-MRSA-IV), EMRSA-16 (ST36-MRSA-II), and the so-called pediatric (ST5-MRSA-IV) clones, while the other two (ST125-MRSA-IVA and ST146-MRSA-IVA) clones could be derived from the pediatric one. The most striking temporal shift in the dominance of MRSA clones was the replacement of the multidrug-resistant and highly epidemic Iberian clone by the so-called British EMRSA-16 clone during the 5-year surveillance period. Our results are in accordance with previously stated findings showing the worldwide hospital dominance of relatively few pandemic and presumably virulent MRSA clones. We report for the first time the detection in Spain of the British EMRSA-15 and pediatric clones, as well as the abrupt replacement of the Iberian by the EMRSA-16 as the major MRSA clone.

Anti-Bacterial Agents↗

PubMed2006

Characterization of a strain of community-associated methicillin-resistant Staphylococcus aureus widely disseminated in the United States.

A highly stable strain of Staphylococcus aureus with a pulsed-field gel electrophoresis type of USA300 and multilocus sequence type 8 has been isolated from patients residing in diverse geographic regions of the United States. This strain, designated USA300-0114, is a major cause of skin and soft tissue infections among persons in community settings, including day care centers and correctional facilities, and among sports teams, Native Americans, men who have sex with men, and military recruits. The organism is typically resistant to penicillin, oxacillin, and erythromycin (the latter mediated by msrA) and carries SCCmec type IVa. This strain is variably resistant to tetracycline [mediated by tet(K)]; several recent isolates have decreased susceptibility to fluoroquinolones. S. aureus USA300-0114 harbors the genes encoding the Panton-Valentine leucocidin toxin. DNA sequence analysis of the direct repeat units within the mec determinant of 30 USA300-0114 isolates revealed differences in only a single isolate. Plasmid analysis identified a common 30-kb plasmid that hybridized with blaZ and msrA probes and a 3.1-kb cryptic plasmid. A 4.3-kb plasmid encoding tet(K) and a 2.6-kb plasmid encoding ermC were observed in a few isolates. DNA microarray analysis was used to determine the genetic loci for a series of virulence factors and genes associated with antimicrobial resistance. Comparative genomics between USA300-0114 and three other S. aureus lineages (USA100, USA400, and USA500) defined a set of USA300-0114-specific genes, which may facilitate the strain's pathogenesis within diverse environments.

Community-Acquired Infections↗

PubMedDate not supplied

[Methicillin-resistant Staphylococcus aureus (MRSA) in veterinary medicine: a "new emerging pathogen"?].

The problem of nosocomial infections is of increasing importance in veterinary medicine. As an example, this review summarizes current knowledge regarding methicillin-resistant Staphylococcus aureus (MRSA) as a typical example, as these pathogens are the most important agents of nosocomial infections in human medicine worldwide and are being increasingly reported in veterinary medicine. MRSA are classified by their ability to be resistant against oxacillin/methicillin, this feature being confered by mecA, a gene which was acquired by horizontal gene transfer of the staphylococcal gene cassette (SCCmec). It is this genetic information that enables MRSA to be resistant against all penicillins, cehalosporins and carbapenems. In addition, MRSA are often resistant against a variety of other antiinfectives, i.e. aminoglycosides, macrolides, lincosamide, streptomycins, tetracyclin, chloramphenicol, but also against fluorquinolones and rifampicin. Presumably, these highly adapted strains are particularly able to acquire resistance genes located on plasmids or transposons. They are also able to develop point mutations, further leading to resistant phenotypes. If these pathogens are leading to infectious diseases, veterinarians may be confronted with a worst-case scenario, being left without any antiinfective therapeutic. As Staphylococcus aureus is highly tenacid, professional hygiene management is of utmost importance. The increasing number of published sporadic MRSA infections, MRSA-infectious diseases as well as MRSA outbreaks in veterinary medicine justifies their recognition as a "New Emerging Pathogen". So far, horses and dogs are mostly affected by MRSA. Although transmission between humans and animals has been reported occasionally, the sources, routes of transmission or the epidemiological relevance of MRSA infections in animals are far from being understood. Therefore, epidemiological investigations utilizing molecular typing tools are mandatory. Typing tools like multilocus-sequence-typing (MLST), pulsefield-gelelectrophoresis (PFGE), sequence analysis of the gene encoding protein A (spa-typing) as well as SCCmec-typing are all at hand.

Animals↗

PubMed2005

Sequence typing and comparison of population biology of Campylobacter coli and Campylobacter jejuni.

A multilocus sequence typing (MLST) scheme that uses the same loci as a previously described system for Campylobacter jejuni was developed for Campylobacter coli. The C. coli-specific primers were validated with 53 isolates from humans, chickens, and pigs, together with 15 Penner serotype reference isolates. The nucleotide sequence of the flaA short variable region (SVR) was determined for each isolate. These sequence data were compared to equivalent information for 17 C. jejuni isolates representing the known genetic diversity of this species. C. coli and C. jejuni share approximately 86.5% identity at the nucleotide sequence level within the MLST loci. There is evidence of genetic exchange of the housekeeping genes between the two species, but at a very low rate; only one sequence type from each species showed evidence of imported DNA. The flaA gene was more variable and has been exchanged many times between the two species, making it an unreliable marker for species identification but useful for distinguishing closely related strains. All but 3 of 21 human C. coli clinical isolates were distinct, according to the combined MLST and SVR sequences. The use of a common MLST scheme allows direct comparisons of the population biology and molecular epidemiology of these two closely related human pathogens.

Animals↗