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PubMed2005

Multilocus sequence typing for differentiation of strains of Candida tropicalis.

A system is described for typing isolates of the pathogenic fungus Candida tropicalis, based on sequence polymorphisms in fragments of six genes: ICL1, MDR1, SAPT2, SAPT4, XYR1, and ZWF1a. The system differentiated 87 diploid sequence types (DSTs) among a total of 106 isolates tested or 80 DSTs among 88 isolates from unique sources. Replicate isolates from the same source clustered together with high statistical similarity, with the exception of one isolate. However, a clade of very closely related isolates included replicate isolates from three different patients, as well as single isolates from eight other patients. This clade, provisionally designated clade 1, was one of three clusters of isolates with high statistical similarity. Five of six isolates in one cluster that may acquire clade status were resistant to flucytosine. This study adds C. tropicalis to Candida albicans and Candida glabrata as Candida species for which a multilocus sequence typing (MLST) system has been set up. The C. tropicalis MLST database can be accessed at http://pubmlst.org/ctropicalis/.

Animals↗

PubMed2005

Population structure and properties of Candida albicans, as determined by multilocus sequence typing.

We submitted a panel of 416 isolates of Candida albicans from separate sources to multilocus sequence typing (MLST). The data generated determined a population structure in which four major clades of closely related isolates were delineated, together with eight minor clades comprising five or more isolates. By Fisher's exact test, a statistically significant association was found between particular clades and the anatomical source, geographical source, ABC genotype, decade of isolation, and homozygosity versus heterozygosity at the mating type-like locus (MTL) of the isolates in the clade. However, these associations may have been influenced by confounding variables, since in a univariate analysis of variance, only the clade associations with ABC type and anatomical source emerged as statistically significant, providing the first indication of possible differences between C. albicans strain type clades and their propensity to infect or colonize different anatomical locations. There were no significant differences between clades with respect to distributions of isolates resistant to fluconazole, itraconazole, or flucytosine. However, the majority of flucytosine-resistant isolates belonged to clade 1, and these isolates, but not flucytosine-resistant isolates in other clades, bore a unique mutation in the FUR1 gene that probably accounts for their resistance. A significantly higher proportion of isolates resistant to fluconazole, itraconazole, and flucytosine were homozygous at the MTL, suggesting that antifungal pressure may trigger a common mechanism that leads both to resistance and to MTL homozygosity. The utility of MLST for determining clade assignments of clinical isolates will form the basis for strain selection for future research into C. albicans virulence.

Analysis of Variance↗

PubMed2005

Clonal spread of a vancomycin-resistant Enterococcus faecium strain among bloodstream-infecting isolates in Italy.

Recent data indicated that the rate of vancomycin resistance in bloodstream-infecting enterococcal isolates in Italy is one of the highest in Europe. The aims of this study were to characterize bloodstream-infecting vancomycin-resistant enterococci (VRE) obtained from various Italian hospitals and to establish whether the isolates were clonally related. During the years 2001 to 2003, a total of 39 VRE isolates were obtained from 19 hospital laboratories in various areas of Italy. Species identification and resistance genotypes of the isolates were obtained by multiplex PCR. Further characterization included antibiotic susceptibility testing, pulsed-field gel electrophoresis (PFGE) of SmaI-digested genomic DNA, detection of virulence genes (esp and hyl), and multilocus sequence typing (MLST) of selected isolates. VRE were identified as 31 Enterococcus faecium (VREfm) isolates and 8 E. faecalis isolates. All but one isolate carried the vanA gene; one VREfm isolate carried the vanB gene. Analysis of the PFGE profiles showed that 28 VREfm isolates shared a similar electrophoretic profile, designed type 1, and were clonally related. All type 1 isolates were resistant to ampicillin, streptomycin, gentamicin, and rifampin and were positive for the esp gene. MLST identified an allelic profile (ST78) comprising purK allele 1, belonging to the C1 clonal lineage, characteristic of human infection and hospital outbreak isolates. The vanB-carrying VREfm isolate, of PFGE type 2, was shown to be a single-locus variant of ST78. Our data indicate that the recent increase in the number of bloodstream infections caused by VRE in Italy is due to the spread of a hospital-adapted, multidrug-resistant VREfm clone belonging to an internationally disseminated lineage.

Anti-Bacterial Agents↗

PubMed2005

Identity and prevalence of multilocus sequence typing-defined clones of group A streptococci within a hospital setting.

Between July and October 2003, 121 clinical isolates of group A streptococci (GAS) were collected from a London hospital and characterized by multilocus sequence typing (MLST) to determine the identity and prevalence of clones circulating within this setting. A total of 39 sequence types (ST), of which 20 were represented by a single isolate, were identified. The eight most prevalent clones among the 121 GAS were ST117/emm81 (16%), ST39/emm4 (9%), ST62/emm87 (7%), ST28/emm1 (6%), ST36/emm12 (6%), ST46/emm22 (5%), ST334/emm82 (5%), and ST101/emm89 (4%). Compared to those in the MLST database (http://spyogenes.mlst.net), 12 (31%) of the 39 STs had not been previously identified, although 7 of these differed from recognized STs at only a single locus, suggesting they were closely related to previously recognized strains. Resistance to erythromycin and tetracycline was seen in 7 and 20% of isolates, respectively, with four isolates resistant to both agents. GAS strains with higher (>80) emm types accounted for 45% of GAS isolates collected during this study. Continuing GAS surveillance, using easily comparable methods, is important for detecting changes in the character of disease-causing isolates.

Anti-Bacterial Agents↗

PubMed2005

Molecular characterization of vancomycin-resistant Enterococcus faecium isolates from Korea.

A total of 98 vancomycin-resistant Enterococcus faecium (VREF) isolates from four tertiary-care hospitals in Korea during the period between 1998 and 2004 were analyzed for genotypic characteristics using the multiplex PCR, multilocus sequence typing (MLST), pulsed-field gel electrophoresis (PFGE), and esp gene analysis. Ninety-two isolates of VREF with VanA phenotype and five of six isolates with VanB phenotype possessed the vanA gene. MLST analysis revealed 9 sequence types (STs), which belonged to a single clonal complex (CC78, clonal lineage C1). Five strains showing incongruence between phenotype and genotype (VanB-vanA) did not belong to the same genotypic clone. The esp gene was detected in all VREF strains, showing 12 different esp repeat profiles. Data suggest that an epidemic clonal group of VREF, CC78 with esp gene, is also present in Asia and has differentiated into multiple diverse genotypic clones during the evolutionary process.

Bacterial Typing Techniques↗

PubMed2005

Comparison of multiple-locus variable-number tandem-repeat analysis with pulsed-field gel electrophoresis, spa typing, and multilocus sequence typing for clonal characterization of Staphylococcus aureus isolates.

Multiple-locus variable-number tandem-repeat analysis (MLVA), a new PCR-based method of typing Staphylococcus aureus, was compared to pulsed-field gel electrophoresis (PFGE), spa typing, and multilocus sequence typing (MLST) on a group of 59 S. aureus (mostly methicillin-resistant) clinical isolates. The aim of the study was to establish possible criteria of clustering MLVA patterns and to check concordance levels between the results produced by MLVA and the three other typing methods. As in our earlier study, MLVA turned out to have discriminatory power similar to that of PFGE. Comparison of data obtained by the two approaches allowed us to propose a 70% or ca. 80% cutoff value of the similarity between two MLVA patterns, depending on a cutoff level applied to interpret the PFGE results, 75% or ca. 90%, respectively. The cutoff values corresponded to the difference of up to six or four bands, respectively, among maximum 14 bands in total produced by two isolates in the analysis. The MLVA clusters matched well those obtained by PFGE, and they were also consistent in general with clusters generated by spa typing and MLST, these latter methods characterized lower resolution. Our results suggest that MLVA may be reliable in shorter-term S. aureus epidemiological studies, including analyses of outbreaks and hospital-to-hospital strain transmission events. Well-known advantages of typing methods based on PCR (low cost, short time, and easiness of performance) make MLVA a method that may be useful in a variety of laboratories, including those performing routine microbiological analyses within medical centers.

Anti-Bacterial Agents↗

PubMed2005

Multilocus sequence typing of methicillin-resistant Staphylococcus aureus from an area of low endemicity by real-time PCR.

A protocol for multilocus sequence typing (MLST) of methicillin-resistant Staphylococcus aureus (MRSA) was adapted to real-time LightCycler System PCR for efficient and rapid amplification of seven housekeeping genes in the same PCR run and real-time detection of the products. The method was evaluated on a representative and well-characterized collection of clinical MRSA isolates (n = 57) obtained from an area of low endemicity. Twenty sequence types (STs) and nine clonal complexes were identified. Combining STs and the staphylococcal cassette chromosome mec (SCCmec) type identified 27 different genotypes, and type IV SCCmec was present in 11 different STs. The presence of the Panton Valentine leukocidin (PVL) genes was found in isolates of four different STs. Eleven different STs were found among the community-acquired as well as among the hospital-acquired MRSA. The genetic heterogeneity was also denoted by pulsed-field gel electrophoresis analysis that showed 24 different pulsotypes among the 57 MRSA isolates. The presence of more than one different type of SCCmec in the same ST indicates that the MRSA clones have arisen at several occasions in the same genetic background by independent acquisition of SCCmec into methicillin-sensitive strains. This circumstance shows the importance of combining MLST data with SCCmec-typing results when investigating the origins of MRSA.

Bacterial Proteins↗

PubMed2005

Comparison of a 3-set genotyping system with multilocus sequence typing for Streptococcus agalactiae (Group B Streptococcus).

Group B streptococcus (GBS; Streptococcus agalactiae) is the most common cause of neonatal and obstetric sepsis and is an increasingly important cause of septicemia in elderly individuals and immunocompromised patients. Epidemiological studies of GBS infections require comprehensive typing systems that provide information about variable characteristics, such as antigenic type, virulence, or antibiotic resistance, as well as the "backbone" structure or the genetic lineage of isolates. We have previously described a 3-set genotyping system that identifies the molecular serotype (MS) or molecular serosubtype (msst), the protein gene profile, and the presence of several mobile genetic elements (F. Kong, D. Martin, G. James, and G. L. Gilbert, J. Med. Microbiol. 52:337-344, 2003). In this study, 83 clinical GBS isolates which had been previously studied by multilocus sequence typing (MLST) (N. Jones, J. F. Bohnsack, S. Takahashi, K. A. Oliver, M. S. Chan, F. Kunst, P. Glaser, C. Rusniok, D. W. Crook, R. M. Harding, N. Bisharat, and B. G. Spratt, J. Clin. Microbiol. 41:2530-2536, 2003) were examined by using the 3-set genotyping system. Genotypes were assigned to five isolates that were nontypeable by conventional serotyping. There were 27 "3-set" genotypes, 24 multilocus sequence types (STs), and 35 unique combinations (or strains), of which the 4 most common, msst III-2 (ST-17), msst III-1 (ST-19), Ia-1 (ST-23), and V-1 (ST-1), accounted for more than 60% of isolates. The 83 isolates were grouped into seven clusters, with a good correlation between the multilocus STs and the genotypes. The combination of 3-set genotyping and MLST adds discriminatory power to strain typing of GBS, which will be useful for future studies of the epidemiology and pathogenesis of GBS disease.

Bacterial Proteins↗

PubMed2005

Multilocus sequence typing of Staphylococcus aureus isolated from high-somatic-cell-count cows and the environment of an organic dairy farm in the United Kingdom.

An outbreak of Staphylococcus aureus intramammary infections on an organic dairy farm was monitored for 10 months. Environmental and milk samples were collected from a total of 26 cows and a group of 21 purchased heifers about to be introduced into the milking herd. There was variation in the rate of isolation of S. aureus (9.5 to 43.8%) from individual mammary quarters, although no S. aureus isolates were detected in the milk samples collected from the heifers. One hundred ninety-one S. aureus isolates were detected from cow milk samples (n = 182), milking machine clusters (n = 4), farm personnel (n = 4), and the environment (n = 1). Multilocus sequence typing (MLST) had a typeability of 100% when it was applied to the 191 isolates. Among the 191 isolates there was limited strain diversity, with seven sequence types (STs) dominated by two strains with closely related STs that differed at a single locus. Within individual mammary quarters there were naturally occurring dual infections, although this was identified in only 0.4% of milk samples. Different strains were associated with variable persistence within quarters. MLST is clearly a very suitable tool for the differentiation and analysis of S. aureus populations detected on dairy cattle farms.

Animals↗

PubMed2005

Multilocus sequence typing of intercontinental bovine Staphylococcus aureus isolates.

A total of 258 bovine-associated Staphylococcus aureus isolates from the United States, Chile, and the United Kingdom, plus the reference isolate S. aureus Newbould 305 (NCIMB 702892), were analyzed by multilocus sequence typing (MLST). A collection of previously characterized United Kingdom isolates were also included in the analysis. The results demonstrated that MLST is suitable for the differentiation of bovine S. aureus isolates from various sites (milk, teat skin, milking machine unit liners, hands, and bedding) and countries. The theory of the host specificity of S. aureus is supported by the detection of a previously undescribed clonal complex that comprised 87.4% of the isolates studied, with representatives from all geographic locations investigated. This suggests that a single clonal group has achieved a widespread distribution and is responsible for the majority of infections. Some sequence types (STs; ST25, ST115, ST124, and ST126) demonstrated site specificity, as they were significantly (P < 0.05) associated with milk or teat skin.

Animals↗

PubMed2005

Clonal analysis of Staphylococcus epidermidis isolates carrying or lacking biofilm-mediating genes by multilocus sequence typing.

Staphylococcus epidermidis is part of the normal microflora of the human skin but is also a leading cause of device-associated infections in critically ill patients. Commensal and clinical S. epidermidis isolates differ in their ability to form biofilms on medical devices; the synthesis of biofilms is mediated by the icaADBC operon. Currently, the epidemiological relatedness between ica-positive and -negative isolates is not known; neither is it known whether the ica genes can spread to biofilm-negative strains through horizontal gene transfer. In this study, multilocus sequence typing (MLST) was employed for the clonal analysis of 118 S. epidermidis ica-positive and -negative strains. MLST revealed that the majority of ica-positive and -negative strains were closely related and formed a single clonal complex. Within this complex one sequence type (ST27) was identified which contained exclusively ica-positive isolates and represented the majority of clinical strains tested. ST27 and related ica-positive clones carried different SCCmec cassettes (conferring methicillin resistance) and the insertion sequence IS256. The findings suggest that the S. epidermidis infections analyzed in this report are mainly caused by a single clone (ST27) which occurs preferentially in hospitals and differs from clones in the community. It is hypothesized that the successful establishment of ST27 within nosocomial environments has been facilitated by the presence of genes encoding biofilm and resistance traits.

Bacterial Adhesion↗

PubMed2006

Evolution and molecular characterization of methicillin-resistant Staphylococcus aureus epidemic and sporadic clones in Cordoba, Argentina.

Since 1999, a new, epidemic, methicillin-resistant Staphylococcus aureus (MRSA) strain, named the "Cordobes clone," has emerged in Argentina and coexists with the pandemic Brazilian clone. The purpose of this study was to determine the stability over time of the new clone and to investigate its evolutionary relationship with epidemic international MRSA lineages and with other MRSA and methicillin-susceptible S. aureus (MSSA) major clones distributed in this region. One hundred three MRSA isolates recovered in 2001 from Cordoba, Argentina, hospitals and 31 MSSA strains collected from 1999 to 2002 were analyzed by their antibiotic resistance patterns, phage typing, and pulsed-field gel electrophoresis. Additionally, representative members of most MRSA defined genotypes (A, B, C, E, K, and I) were characterized by multilocus sequence typing (MLST) and spaA and SCCmec typing. The most prevalent MSSA pulsotypes were also analyzed by MLST. Our results support the displacement of the Brazilian clone (sequence type [ST] 239, spaA type WGKAOMQ, SCCmec type IIIA) by the Cordobes clone (ST5, spaA type TIMEMDMGMGMK, SCCmec type I) in the hospital environment. MRSA and MSSA isolates shared only ST5. The data support the origin of the Cordobes clone as a member of a lineage that includes the pediatric and New York/Japan international clones and that is genetically related to the British EMRSA-3 strain. Interestingly, the pediatric clone, isolated from most community-acquired infections in Cordoba, was characterized by ST100, a single-locus variant of ST5 and a new variant of SCCmec type related to SCCmec type IVc.

Anti-Bacterial Agents↗

PubMed2006

Multilocus sequence typing of Porphyromonas gingivalis strains from different geographic origins.

Porphyromonas gingivalis is an important periodontal pathogen that can be isolated from both active and inactive periodontal lesions. Apparently, differences in virulence between P. gingivalis strains exist, but the mechanisms underlying these differences are not yet fully understood. To obtain more information about pathogenicity and virulence of P. gingivalis, it is relevant to assess the genetic population structure of the species and to examine the occurrence of putative virulence factors against the genetic background. Presently, multilocus sequence typing (MLST) is the best method for analyzing bacterial population structures. Forty P. gingivalis strains from worldwide sources were analyzed by MLST. Internal 310- to 420-bp DNA fragments of the eight ubiquitous chromosomal genes, ftsQ, hagB, gdpxJ, pepO, mcmA, recA, pga, and nah, were amplified by PCR and then sequenced. The number of alleles at individual loci ranged from 2 to 19, and a total of 33 allelic profiles, or sequence types (STs), were identified. Nucleotide variation between alleles was located at one or a few sites. Identical or similar STs were found in isolates from different geographic regions. Our results showed signs of a clonal population structure with a level of recombination not as high as that previously suggested for the species. We also found that P. gingivalis isolates from individual patients were genetically heterogeneous.

Alleles↗

PubMed2006

Use of a variable amplicon typing scheme reveals considerable variation in the accessory genomes of isolates of Burkholderia pseudomallei.

Melioidosis, a disease caused by the bacterium Burkholderia pseudomallei, is endemic in southeast Asia and northern Australia. We used suppression subtractive hybridization (SSH) to identify sequences that varied between two B. pseudomallei isolates from Australia and determined the distribution of 45 SSH-derived sequences among a panel of B. pseudomallei and B. thailandensis isolates. Sequences exhibiting variable prevalence were included in a variable amplicon typing (VAT) scheme designed to score the presence or absence of 14 PCR amplicons. VAT analysis was carried out with 48 isolates from Thailand, which were typed by multilocus sequence typing (MLST), and 44 isolates from Australia of known MLST type. The VAT scheme could be used to divide the 48 isolates from Thailand into 23 VAT types and the 44 isolates from Australia into 36 VAT types. Some of the sequences included in the VAT scheme were more commonly PCR positive among isolates from Australia than among isolates from Thailand, and vice versa. No isolate from Australia was PCR positive for genomic island 11 or a putative transposase sequence, whereas four SSH-derived sequences were far more prevalent among the Australian isolates. Analysis based on the VAT scheme indicated that the isolates clustered into groups, some of which were mainly or exclusively from one geographical origin. One cluster included Australian isolates that were mostly associated with severe disease, including rare neurological melioidosis, suggesting that the content of the accessory genome may play an important role in determining the clinical manifestation of the disease.

Bacterial Typing Techniques↗

PubMed2006

Clonal composition of Staphylococcus aureus isolates at a Brazilian university hospital: identification of international circulating lineages.

In only a few instances has the clonal composition of Staphylococcus aureus collections that include methicillin-susceptible S. aureus (MSSA) been extensively characterized. In order to investigate the clonal composition of MSSA and methicillin-resistant S. aureus (MRSA) and examine whether the infections diagnosed at our hospital were related to internationally distributed S. aureus lineages, we collected 89 clinical S. aureus isolates from patients at a public university hospital in Rio de Janeiro, Brazil, from September 1999 to June 2000. All S. aureus isolates were genotyped by pulsed-field gel electrophoresis and multilocus restriction fragment typing (MLRFT), and a subset (n = 17) was further characterized by multilocus sequence typing (MLST). The 34 MRSA isolates were additionally characterized by SCCmec typing. The MSSA population (n = 55) was grouped into 18 restriction fragment types (RFTs); of these, five RFTs accounted for 67% (37) of the MSSA isolates. MRSA isolates were clustered into only three RFTs (P = 0.02). The majority of MSSA RFTs were related to sequence type 30 (ST30) (12 isolates, 22%), ST1, ST188, and ST432 (6 isolates, 11% each). The predominant MRSA RFT comprised 31 (91%) of 34 isolates; four randomly selected isolates of this RFT were ST239, the previously described widely disseminated Brazilian clone. However, a fifth isolate belonging to this RFT was the ST644, a new single locus variant of ST239. By applying MLRFT and MLST, we found evidence for a clonal structure in MSSA isolates and detected the dissemination of MSSA clonal complexes 1, 5, 8, 30, and 45.

Adolescent↗

PubMed2006

Multilocus sequence typing reveals intrafamilial transmission and microevolutions of Candida albicans isolates from the human digestive tract.

Candida albicans is a human commensal that is also responsible for superficial and systemic infections. Little is known about the carriage of C. albicans in the digestive tract and the genome dynamics that occur during commensalisms of this diploid species. The aim of this study was to evaluate the prevalence, diversity, and genetic relationships among C. albicans isolates recovered during natural colonization of the digestive tract of humans, with emphasis on Crohn's disease patients who produce anti-yeast antibodies and may have altered Candida sp. carriage. Candida sp. isolates were recovered from 234 subjects within 25 families with multiple cases of Crohn's disease and 10 control families, sampled at the oral and fecal sites. Prevalences of Candida sp. and C. albicans carriage were 53.4% and 46.5%, respectively, indicating frequent commensal carriage. No differences in prevalence of carriage could be observed between Crohn's disease patients and healthy subjects. Multilocus sequence typing (MLST) of C. albicans isolates revealed frequent colonization of a subject or several members of the same family by genetically indistinguishable or genetically close isolates. These latter isolates differed by loss-of-heterozygosity events at one or several of the MLST loci. These loss-of-heterozygosity events could be due to either chromosome loss followed by duplication or large mitotic recombination events between complementary chromosomes. This study was the first to jointly assess commensal carriage of C. albicans, intrafamilial transmission, and microevolution. The high frequency of each of these events suggests that the digestive tract provides an important and natural niche for microevolutions of diploid C. albicans through the loss of heterozygosity.

Bacterial Typing Techniques↗

PubMed2025

Comparative genomics of carbapenem-resistant Acinetobacter baumannii isolated from pediatric patients in a tertiary care hospital.

Acinetobacter baumannii is a short gram-negative bacillus, notable for its intrinsic multidrug resistance and genomic plasticity, which facilitates the acquisition of additional resistance genes via mobile genetic elements. Due to its increasing carbapenem resistance, the World Health Organization has classified it as a critical priority pathogen. This study performed a comparative genomic analysis of 20 carbapenem-resistant A. baumannii clinical strains isolated from the Hospital Infantil de México Federico Gómez (CRAB-HIMFG), alongside 11 genomes from other Mexican strains. The pangenome was determined to be open, and core genome single-nucleotide polymorphism-based analysis grouped the CRAB-HIMFG strains within CC758/IC5 and CC92/IC2. A novel sequence type (ST) in the MLST-Pasteur scheme was identified, related to STPas156, and in the MLST-Oxford scheme, associated with STOxf758 and STOxf1054. Virulence and resistance genes comprised 0.61% to 2.23% of the pangenome. Oxacillinase genes and efflux pumps primarily mediated carbapenem resistance, while virulence genes included those encoding biofilm and type IV pili. Capsule typing revealed a correlation with established international clones, IC2 and IC5. Plasmids exhibited high diversity, harboring maintenance modules and toxin-antitoxin systems, with the dissemination of resistance genes linked to insertion sequences. Biofilm formation and twitching motility were not always expressed, as they depend on additional environmental factors. Our study shows that comparative genomics is an essential tool to analyze clinically and epidemiologically significant genomes, providing critical insights into gene distribution, genomic architecture, and horizontal gene transfer mechanisms in microbial populations.IMPORTANCEIn recent years, a reported increase in the mortality rate associated with infections caused by A. baumannii, along with a rise in carbapenem resistance, poses a serious clinical challenge. The WHO considered this microorganism critical for research into alternative therapies and epidemiological surveillance. Despite advances in bioinformatics, genomic studies have yet to fully elucidate the structural rearrangements and secretion systems of A. baumannii. This knowledge gap hinders our understanding of its remarkable genomic plasticity and its ability to acquire and spread resistance and virulence genes through horizontal gene transfer.

Acinetobacter baumannii↗

PubMed2006

Molecular epidemiology and emergence of worldwide epidemic clones of Neisseria meningitidis in Taiwan.

BACKGROUND: Meningococcal disease is infrequently found in Taiwan, a country with 23 million people. Between 1996 and 2002, 17 to 81 clinical cases of the disease were reported annually. Reported cases dramatically increased in 2001-2002. Our record shows that only serogroup B and W135 meningococci have been isolated from patients with meningococcal disease until 2000. However, serogroup A, C and Y meningococci were detected for the first time in 2001 and continued to cause disease through 2002. Most of serogroup Y meningococcus infections localized in Central Taiwan in 2001, indicating that a small-scale outbreak of meningococcal disease had occurred. The occurrence of a meningococcal disease outbreak and the emergence of new meningococcal strains are of public health concern. METHODS: Neisseria meningitidis isolates from patients with meningococcal disease from 1996 to 2002 were collected and characterized by serogrouping, pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST). The genetic relatedness and clonal relationship between the isolates were analyzed by using the PFGE patterns and the allelic profiles of the sequence types (STs). RESULTS: Serogroups A, B, C, W135, Y, and non-serogroupable Neisseria meningitidis were, respectively, responsible for 2%, 50%, 2%, 35%, 9%, and 2% of 158 culture-confirmed cases of meningococcal disease in 1996-2002. Among 100 N. meningitidis isolates available for PFGE and MLST analyses, 51 different PFGE patterns and 30 STs were identified with discriminatory indices of 0.95 and 0.87, respectively. Of the 30 STs, 21 were newly identified and of which 19 were found in serogroup B isolates. A total of 40 PFGE patterns were identified in 52 serogroup B isolates with the patterns distributed over several distinct clusters. In contrast, the isolates within each of the serogroups A, C, W135, and Y shared high levels of PFGE pattern similarity. Analysis of the allelic profile of the 30 STs suggested the serogroup B isolates be assigned into 5 clonally related groups/ clonal complexes and 7 unique clones. The ST-41/44 complex/Lineage 3, and the ST-3439 and ST-3200 groups represented 79% of the serogroup B meningococci. In contrast, isolates within serogroups A, serogroup W135 (and C), and serogroup Y, respectively, simply belonged to ST-7, ST-11, and ST-23 clones. CONCLUSION: Our data suggested that serogroup B isolates were derived from several distinct lineages, most of which could either be indigenous or were introduced into Taiwan a long time ago. The serogroup A, W135 (and C), and Y isolates, respectively, belonged to the ST-7, ST-11, and ST-23, and the represented clones that are currently the major circulating clones in the world and are introduced into Taiwan more recently. The emergence of serogroup A, C and Y strains contributed partly to the increase in cases of meningococcal disease in 2001-2002.

Communicable Diseases, Emerging↗