Multilocus Sequence Typing Analysis of Invasive and Non-Invasive Group B Streptococcus of Hospital Origin in Malaysia
Menagah EzhumalaiAbdulRahman MuthannaZarizal SuhailiNurul Diana DzaralySyafinaz Amin NordinMohammad Noor Azmai AmalMohd Nasir Mohd Desa
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Abstract:
The aim of this study was to study the genotype of a hospital collection of Group B Streptococcus (GBS) from invasive and non-invasive sites. Fifty-one pre-characterised human of GBS were re-identified and further analysed by multilocus sequence typing (MLST) in relation to previously published serotypes. Fifteen sequence types (ST) were found with ST1 being the most predominant. ST1 was also associated with majority of the invasive isolates. The genotypic distribution patterns of GBS in this study were largely in agreement with previous reports from other countries indicating the tendency of certain genotypes to prevail in human infection settings.Keywords:
Multilocus sequence typing
Group B
Sequence (biology)
목적 : 임신부에서 group B streptococcus의 보균율을 알아보고 감염 여부와 분만 전후 임신부 및 태아의 주산기 예후와의 관계를 알아보고자 하였다.
연구 방법 : 2000년 1월 1일부터 2001년 6월 30일까지 인하대학교 의과대학 인하병원 산부인과에 산전 진찰을 위하여 내원한 임신 35주 이후 임신부를 대상으로 하였다. 검체는 임신부의 질 하부와 회음부에서 채취 하였고 이를 선택 배지에서 배양하여 group B streptococcus의 유무를 판정하였다. 대상 임신부는 group B streptococcus 보균 유무와 분만 전후 임신부와 신생아의 주산기 예후를 비교하였다.
결과 : 204명의 임신부들을 대상으로 Group B streptococcus 배양 검사를 시행한 결과 4명 (1.96%)에서 양성 반응을 보였다. 신생아중 group B streptococcus 감염은 없었다. Group B streptococcus 배양 검사에서 양성을 보인 임신부와 음성을 보인 임신부의 주산기 예후는 통계학적인 차이는 없었다.
결론 : 본 연구에서 임신부의 group B streptococcus 보균율은 1.96%로 미국의 보균율 (10∼30%)보다 낮았으며, 신생아 감염률은 0%로 임신부에서 group B streptococcus 선별 검사로써의 유용성이 낮은 것으로 사료된다. 그러나 최근 group B streptococcus는 임신부에게 조기 진통, 조기 양막 파수, 융모 양막염, 산욕기 감염, 분만 후 모성 골수염 등의 합병증을 야기하며 신생아에 있어서 사산, 패혈증 및 뇌수막염을 비롯한 조기 또는 지연되어 발현하는 여러 합병증을 유발하는 것으로 알려져 있어 국내 임신부에서 group B streptococcus 감염의 임상적 의의를 알기 위해서는 더 많은 연구가 필요할 것으로 사료된다.
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Molecular strain typing is essential for deciphering the epidemiology of Campylobacter jejuni infections. We applied two different methods, multilocus sequence typing (MLST) and analysis of the flaA short variable repeat (SVR), to 289 isolates (163 human, 56 chicken, 34 raw milk, and 36 environmental water isolates) collected in the province of Québec, Canada, over 3 years; in addition, the analysis included the pulsed-field gel electrophoresis (PFGE) typing results for a subset of 131 isolates studied previously. MLST defined 96 sequence types (STs) and 20 clonal complexes (CCs), including 49 STs (73 isolates, 25%) and 39 alleles not previously documented in an international database. The frequency of new STs was significantly higher among water isolates than among isolates from other sources (18/36 [50%] and 55/253 [22%], respectively; P < 0.001). Nine of the 10 most prevalent CCs included isolates from humans and at least one other source; five CCs comprised exclusively or mostly human and chicken isolates. However, water and milk were the predominant nonhuman sources among the remaining CCs, suggesting that sporadic C. jejuni infections in humans may frequently arise from sources other than chickens. All three typing systems were discriminatory (discriminatory index > 0.9). Among 131 isolates analyzed by PFGE, each of the 20 types represented by two or more isolates corresponded to a single CC. In contrast, among the 14 most prevalent types detected by analysis of the flaA SVR (5 to 27 isolates each), 8 (57%) included isolates that represented multiple different CCs. The basis for these discordant results was uncertain. Antimicrobial resistance was randomly distributed among the CCs and appeared to be more closely related to the source of an isolate than its genotype. Although MLST is labor-intensive and expensive, it remains the single best method for the genotyping of C. jejuni isolates and deciphering the epidemiologic relationships among isolates.
Multilocus sequence typing
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ABSTRACT The choice of adequate methods for epidemiological purposes remains a challenging problem in Neisseria gonorrhoeae molecular monitoring. In this study, the collection of geographically unrelated gonococci ( n = 103) isolated in Russian clinics was comparably tested by (i) a traditional serotyping scheme, (ii) por typing, (iii) Neisseria gonorrhoeae multiantigen sequence typing (NG-MAST), and (iv) multilocus sequence typing (MLST). It is shown that, according to sequencing data, a third of the strains carried new porB1 alleles, as well as tbpB ones, and more than half of the samples had new sequence types (STs) as determined by NG-MAST or MLST. The discriminatory power for each typing method was calculated by using the Hunter-Gaston discriminatory index, D . Commonly, modern nucleic acid-based typing methods ( por typing, NG-MAST, and MLST) appeared to be more efficient than the classical serotyping scheme. While the traditional serotyping gave a D value of 0.82, the por typing, NG-MAST, and MLST approaches yielded D values of 0.97, 0.98, and 0.91, respectively. Each typing technique revealed the distribution of gonococci slightly correlated with their geographical sources. However, only the MLST method STs were highly associated with certain phenotypes. Although ST1594, ST1892, and ST6720 were typical for susceptible gonococci, ST1901 and ST6716 were undoubtedly associated with a multidrug-resistant phenotype. We conclude that every tested nucleic acid-based typing method is suitable for N. gonorrhoeae molecular surveillance. However, the MLST method seems to serve large-scale epidemiological purposes, whereas the NG-MAST and por typing approaches are more appropriate for the investigation of local outbreaks.
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We investigated the relationship between colonizing and invasive isolates from patients with candidaemia. Molecular typing was performed using random amplification of polymorphic DNA (RAPD) and multilocus sequence typing (MLST). We found MLST to be sufficient for typing Candida isolates, and that surveillance cultures are helpful in predicting concomitant invasive isolates, but not necessarily the pathogen involved in subsequent episodes.
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ABSTRACT Methicillin-resistant Staphylococcus aureus (MRSA) is a major nosocomial pathogen in India, and up to 70% methicillin resistance has been reported from hospitals in various parts of India. Hospitals use phenotyping for the most part, and molecular genotyping is not done. Here we report on the genotyping of 82 single-patient isolates from two hospitals in Bangalore, South India, for the first time. Most of the strains possessed type III or IIIA staphylococcal cassette chromosome ( SCCmec ) cassettes, and we did not detect strains with type I, IA, or II cassettes. Most isolates also contained the type III cassette chromosome recombinase ( ccr ) AB region. Multilocus sequence typing (MLST) and staphylococcal protein A ( spa ) typing of a selected number of isolates have been carried out. Although most isolates that were chosen for MLST and spa typing had the same patterns, they were quite diverse in their pulsed-field gel electrophoresis (PFGE) patterns. PFGE, MLST, and spa typing of the Indian strains revealed that they are related to the previously described Hungarian and Brazilian clones.
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108 isolates of Staphylococcus aureus, belonging to six large ribogroups according to the automated Ribo-Printer® system, were studied with two highly used molecular methods for epidemiological studies, namely multi-locus sequence typing (MLST) and spa typing, followed by BURP and eBURST v3 analysis for clustering spa types and sequence (ST) types. The aim was to evaluate whether automated ribotyping could be considered a useful screening tool for identifying S. aureus genetic lineages with respect to spa typing and MLST. Clarifying the relationship of riboprinting with these typing methods and establishing whether ribogroups fit single clonal complexes were two main objectives. Further information on the genetic profile of the isolates was obtained from agr typing and the search for the mecA, tst genes, and the IS256 insertion sequence. Automated ribotyping has been shown to predict spa clonal complexes and MLST clonal complexes. The high cost and lower discriminatory power of automated ribotyping compared to spa and MSLT typing could be an obstacle to fine genotyping analyzes, especially when high discriminatory power is required. On the other hand, numerous advantages such as automation, ease and speed of execution, stability, typeability and reproducibility make ribotyping a reliable method to be juxtaposed to gold standard methods.
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Ribotyping
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Multilocus sequence typing
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Phenotypic methods were initially used for bacterial typing yet they have a number of drawbacks limiting their use. Methods of molecular and genetic typing have become wide-spread today. Among these methods, bacterial typing based on multilocus sequence typing (Multilocus Sequence Typing - MLST) has been developing at the fastest rate. However, schemes of molecular and genetic typing of STD pathogens as compared to other bacteria are insufficiently developed, which considerably complicates the planning of measures aimed at the reduction of their spread.
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Neisseria gonorrhoeae
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Group B streptococcus is the most common cause of neonatal sepsis in the United States of America (USA). This study was undertaken to determine the contribution of group B streptococcus to neonatal septicaemia in Antigua and Barbuda. From 1994 to 2002, there were about 12,000 births, with 2500 Special Care Nursery admissions, 1100 (44%) with potential neonatal septicaemia. Blood cultures were done in 433/1100 (39%) and cerebrospinal fluid cultures in 52/1100 (5%). Positive cultures were seen in 41/433 (9.5%) with group B streptococcus in 1/41 (2.4%), streptococcus "species" in 3/41 (7.4%) and positive cerebrospinal fluid cultures were seen in 2/52 (one group B streptococcus) giving 5 per 12,000 or 0.4 cases per 1000 babies. Vaginal cultures from 1994 to 2002 revealed group B streptococcus in 14/163 (8.6%) of positive bacterial cultures. A sample of pregnant women from a private office had positive culture for group B streptococcus in 2/120 (1.7%). The prevalence rate of carriage (15 to 40%) and infection (1.7 to 4 per 1000 babies) was much higher in the USA in the same period Universal screening of mothers for group B streptococcus may not be as necessary or cost-effective in Antigua and Barbuda.
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Neonatal Sepsis
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Carriage
Blood Culture
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We explored the relevance of a Clustered regularly interspaced short palindromic repeats (CRISPR)-based genotyping tool for Streptococcus agalactiae typing and we compared this method to current molecular methods [multi locus sequence typing (MLST) and capsular typing]. To this effect, we developed two CRISPR marker schemes (using 94 or 25 markers, respectively). Among the 255 S. agalactiae isolates tested, 229 CRISPR profiles were obtained. The 94 and 25 markers made it possible to efficiently separate isolates with a high diversity index (0.9947 and 0.9267, respectively), highlighting a high discriminatory power, superior to that of both capsular typing and MLST (diversity index of 0.9017 for MLST). This method has the advantage of being correlated with MLST [through analysis of the terminal direct repeat (TDR) and ancestral spacers] and to possess a high discriminatory power (through analysis of the leader-end spacers recently acquired, which are the witnesses of genetic mobile elements encountered by the bacteria). Furthermore, this “one-shot” approach presents the benefit of much-reduced time and cost in comparison with MLST. On the basis of these data, we propose that this method could become a reference method for group B Streptococcus (GBS) typing.
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