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result(s) for
"Multilocus sequence typing"
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Multilocus sequence typing of clinical and colonizing isolates of Acinetobacter baumannii and comparison with the world isolates
by
Choudhary, Jyoti
,
Shariff, Malini
in
Acinetobacter baumannii
,
Acinetobacter baumannii - classification
,
Acinetobacter baumannii - drug effects
2025
Objectives
To establish the epidemiological correlation between the study isolates, Indian and World isolates of
Acinetobacter baumannii
by performing Multilocus Sequence typing.
Materials and methods
A total of 181 isolates (Sputum (
n
= 116), lower respiratory tract other than sputum (
n
= 36), upper respiratory tract (
n
= 20), Environment (medical) (
n
= 4), and Blood (
n
= 5) of
Acinetobacter baumannii
were retrieved from our repository. DNA was isolated and Multilocus Sequence Typing was performed according to the Pasteur scheme. The amplified fragments were sequenced by outsourcing, and the locus and the sequence types were determined as given in the PUBMLST site. The clonal complexes were assigned using eBURST.
Results and conclusion
Of the 181 isolates, 20 were colonizers and 4 were from hospital environments. All the study isolates were multidrug-resistant (MDR) and 4 of them were extensively drug-resistant (XDR). 23 sequence types were unique and were assigned new sequence types. Among them, 2125 (
n
= 12), an SLV (Single Locus Variant) of 2, was the commonest followed by 2126 (
n
= 2) which was a DLV (Double Locus Variant) of 2 and an SLV of 2125. Others were singletons. Among the known STs, 149 (
n
= 72) was the commonest followed by ST 2 (
n
= 62) & 415 (
n
= 5), ST 10 (
n
= 4), ST 15, ST622 and ST1482 (3 each). ST149 had 1SLV ST1482 (
n
= 3). ST 2 has 5 SLVs (415, 1555, 2125, 2128, & 2131, and 2 DLVs (2130 & 2126). eBURST analysis of the study isolates showed three groups: Group I (86 isolates) with ST 2 as the primary founder, group II (6 isolates) and group III (79 isolates) with ST 149 as the primary founder. All the other 11 isolates were singletons. There was no difference in antimicrobial sensitivity or sequence types of clinical and colonizing isolates. The sequence types of study isolates were compared to the world isolates in the PUBMLST database. To conclude, MLST is an important tool for establishing isolates’ phylogenetic relationships.
Acinetobacter baumannii
being an important nosocomial pathogen should be routinely screened for the frequent changes in the sequence types to demonstrate the emerging resistance patterns and other changes.
Journal Article
Assessing mutation accumulation in DNA repair-deficient Listeria monocytogenes : implications for cgMLST cluster thresholds in outbreak analysis
by
Füszl, Astrid
,
Blaschitz, Marion
,
Schindler, Stefanie
in
allele threshold
,
Alleles
,
Antibiotics
2025
is primarily transmitted via contaminated food and can cause listeriosis, an infection often associated with sepsis and meningitis in at-risk individuals. Accurate outbreak detection relies on whole genome sequencing (WGS) and core genome multilocus sequence typing (cgMLST), which use allele thresholds to identify related strains.
This study investigated mutation rates in
, focusing on isolates with DNA repair deficiencies. Serial subcultivations were performed, comparing a repair-deficient isolate with a wild-type control. Genetic variability was assessed using WGS and cgMLST.
Mutation rates were significantly higher in repair-deficient isolates, exceeding typical cgMLST thresholds currently used in
outbreak investigations, leading to a misclassification of related isolates as unrelated. An additional analysis of the Austrian
database revealed that such deficiencies are rare among isolates.
The standard 7-allele cgMLST threshold effectively identifies related strains in most cases, but may require adjustments for hypermutator strains. Incorporating DNA repair data could improve the accuracy of outbreak investigations, ensuring reliable public health responses.
Journal Article
Clonal Diversity of Candida auris, Candida blankii, and Kodamaea ohmeri Isolated from Septicemia and Otomycosis in Bangladesh as Determined by Multilocus Sequence Typing
2023
Candida auris, Candida blankii, and Kodamaea ohmeri have been regarded as emerging fungal pathogens that can cause infections with high mortality. For genotyping of C. auris, a multilocus sequence typing (MLST) scheme based on four locus sequences has been reported, while there is no typing scheme for C. blankii and K. ohmeri. In the present study, the existing MLST scheme of C. auris was modified by adding more locus types deduced from sequence data available in the GenBank database. Furthermore, MLST schemes of C. blankii and K. ohmeri were developed using the four cognate loci (ITS, RPB1, RPB2, D1/D2) and similar sequence regions to those of C. auris. These MLST schemes were applied to identify the ST (sequence type) of clinical isolates of C. auris (n = 7), C. blankii (n = 9), and K. ohmeri (n = 6), derived from septicemia or otomycosis in Bangladesh in 2021. All the C. auris isolates were classified into a single ST (ST5) and clade I, having a Y132F substitution in ERG11p, which is associated with azole resistance. Similarly, all the C. blankii isolates belonged to a single type (ST1). In contrast, six K. ohmeri isolates were assigned to five types (ST1-ST5), suggesting its higher genetic diversity. These findings revealed the availability of MLST schemes for these three fungal species for understanding their clonal diversity among clinical isolates.
Journal Article
MLST genotypes of Campylobacter jejuni isolated from broiler products, dairy cattle and human campylobacteriosis cases in Lithuania
by
Tamuleviciene, Egle
,
Kasnauskyte, Neringa
,
Ramonaite, Sigita
in
Analysis
,
Animals
,
Bacterial and fungal diseases
2017
Background
Campylobacter
(
C.
)
jejuni
is the leading cause of human campylobacteriosis worldwide. We performed a molecular epidemiological study to investigate the genetic relationship among
C. jejuni
strains isolated from human diarrhoeal patients, broiler products and dairy cattle in Lithuania.
Methods
The
C. jejuni
isolates from human clinical cases, dairy cattle and broiler products were genotyped using multilocus sequence typing (MLST). Allele numbers for each housekeeping gene, sequence type (ST), and clonal complex (CC) were assigned by submitting the DNA sequences to the
C. jejuni
MLST database (
http://pubmlst.org/campylobacter
). Based on the obtained sequence data of the housekeeping genes a phylogenetic analysis of the strains was performed and a minimum spanning tree (MST) was calculated.
Results
Among the 262
C. jejuni
strains (consisting of 43 strains isolated from dairy cattle, 102 strains isolated from broiler products and 117 clinical human
C. jejuni
strains), 82 different MLST sequence types and 22 clonal complexes were identified. Clonal complexes CC21 and CC353 predominated among the
C. jejuni
strains. On ST-level, five sequence types (ST-5, ST-21, ST-50, ST-464 and ST-6410) were dominating and these five STs accounted for 35.9% (
n
= 94) of our isolates. In addition, 51 (19.5%)
C. jejuni
strains representing 27 (32.9%) STs were reported for the first time in the PubMLST database (
http://pubmlst.org/campylobacter
). The highest Czekanowski index or proportional similarity index (PSI) was calculated for
C. jejuni
strains isolated from human campylobacteriosis cases and broiler products (PSI = 0.32) suggesting a strong link between broiler strains and human cases. The PSI of dairy cattle and human samples was lower (PSI = 0.11), suggesting a weaker link between bovine strains and human cases. The calculated Simpson’s index of all
C. jejuni
isolates showed a high genetic diversity (D = 0.96).
Conclusion
Our results suggest that broiler products are the most important source of human campylobacteriosis in Lithuania. The study provides information on MLST type distribution and genetic relatedness of
C. jejuni
strains from humans, broiler products and dairy cattle in Lithuania for the first time, enabling a better understanding of the transmission pathways of
C. jejuni
in this country.
Journal Article
Multilocus sequence typing analysis and second‐generation sequencing analysis of Salmonella Wandsworth
by
Zhang, Chunling
,
Xu, Xuebin
,
Wang, Yichao
in
Agglutination
,
Amino acids
,
Aminoglycoside antibiotics
2021
Background
Salmonella Wandsworth is a rare serotype of Salmonella. This study analyzed the genotyping, genome structure, and molecular biological functions of Salmonella Wandsworth based on the results of multilocus sequence typing and next‐generation sequencing genome assembly analysis.
Methods
Serological typing was performed using the slide‐agglutination method. The micro broth dilution method was used to test antibiotic susceptibility. Multilocus sequence typing (MLST) was used to perform the homology analysis, while the second‐generation sequencing genome analysis was used to analyze the whole genome of the bacteria.
Results
Salmonella Wandsworth is Group Q Salmonella. The MLST of this strain was ST1498. Salmonella Wandsworth was sensitive to antibiotics, such as ceftriaxone, imipenem, chloramphenicol, and colistin, but was resistant to ampicillin, cefalotin, gentamicin, and ciprofloxacin. The second‐generation sequencing results showed that the genome sequence length of the bacteria was 5109457bp. Annotated COG library analysis generated 3,746 corresponding genes. After the comparison with the KEGG library, 1,340 genes, which participate in 19 types of metabolic pathways, were obtained. A total of 249 pathogenic factors and 2 disease islands were predicted. 2 CRISPR sites and 8 Cas sites were predicted. It can be seen from the evolutionary tree that Salmonella Wandsworth MLST1498 and Paratyphi B str.SPB7 are gathered together. We identified one resistance gene, namely, aac(6’)‐Iaa accounting for aminoglycoside resistance.
Conclusion
Salmonella Wandsworth isolated in this study is Salmonella group Q. Consequently, it is necessary to strengthen the understanding of clinical infections of Salmonella Wandsworth and carry out continuous monitoring and research.
Salmonella Wandsworth is a rare serotype of Salmonella. Based on genome sequences, We employed the alignment and assembly‐free (AAF) method to construct a genomic evolutionary tree.
Journal Article
Co-infection, reinfection and superinfection with Anaplasma phagocytophilum strains in a cattle herd based on ankA gene and multilocus sequence typing
by
Langenwalder, Denis B.
,
Nieder, Marion
,
von Loewenich, Friederike D.
in
Alleles
,
Anaplasma phagocytophilum
,
Anaplasma phagocytophilum - classification
2020
Background
Anaplasma phagocytophilum
is a Gram-negative obligate intracellular bacterium that replicates in neutrophil granulocytes. It is transmitted by ticks of the
Ixodes ricinus
complex and causes febrile illness in humans and animals. We used multilocus sequence typing (MLST) and
ankA
gene-based typing to study the molecular epidemiology of the
A. phagocytophilum
strains circulating in a German cattle herd over one pasture season. The aim was to investigate whether co-infection with two distinct variants, reinfection with the same and/or superinfection by a different strain occurred during one pasture season. Eight genetic loci were sequenced in 47 PCR-positive samples from 15 animals.
Results
Five different sequence types (ST) and four
ankA
alleles were detected in the cattle herd. Three different ST caused clinically overt tick-borne fever in primary infected animals. The concordance between ST and
ankA
allele was 100%. Therefore, the housekeeping genes used for MLST and the highly variable
ankA
gene were concatenated to increase resolution. Co-infection could be proven because samples of chronologically close collection dates were included. Co-infecting
A. phagocytophilum
strains differed by 14 to 18 single nucleotide polymorphisms (SNPs). Most superinfecting variants varied by 14 SNPs from the previous strain and appeared in median after a free interval of 31 days. Thus, it is unlikely that superinfecting strains arose by in-animal evolution. Immunity against re- or superinfection was assumed because the cattle developed clinical signs only during primary infection.
Conclusions
The tick-pathogen-vertebrate host interaction is probably much more complex than previously thought taking into account the frequently occurring events of co-infection, reinfection and superinfection. This complex situation could not be easily simulated in an experimental infection and underlines the value of field studies.
Journal Article
Subtyping Options for Microsporum canis Using Microsatellites and MLST: A Case Study from Southern Italy
2021
Microsporum canis is considered one of the most common zoophilic dermatophyte species causing infections in animals and humans worldwide. However, molecular epidemiological studies on this dermatophyte are still rare. In this study, we aimed to analyse the population structure and relationships between M. canis strains (n = 66) collected in southern Italy and those isolated from symptomatic and asymptomatic animals (cats, dogs and rabbits) and humans. For subtyping purposes, using multilocus sequence typing (MLST) and multilocus microsatellite typing (MLMT), we first used a limited set of strains to screen for variability. No intraspecies variability was detected in six out of the eight reference genes tested and only the ITS and IGS regions showed two and three sequence genotypes, respectively, resulting in five MLST genotypes. All of eight genes were, however, useful for discrimination among M. canis, M. audouinii and M. ferrugineum. In total, eighteen microsatellite genotypes (A–R) were recognized using MLMT based on six loci, allowing a subdivision of strains into two clusters based on the Bayesian iterative algorithm. Six MLMT genotypes were from multiple host species, while 12 genotypes were found only in one host. There were no statistically significant differences between clusters in terms of host spectrum and the presence or absence of lesions. Our results confirmed that the MLST approach is not useful for detailed subtyping and examining the population structure of M. canis, while microsatellite analysis is a powerful tool for conducting surveillance studies and gaining insight into the epidemiology of infections due to this pathogen.
Journal Article
Infection Control for a Carbapenem-Resistant Enterobacteriaceae Outbreak in an Advanced Emergency Medical Services Center
by
Miura, Miho
,
Takasu, Osamu
,
Miyamoto, Naoki
in
Antimicrobial agents
,
carbapenem-resistant Enterobacteriaceae (CRE)
,
carbapenemase
2021
Background: A carbapenem-resistant Enterobacteriaceae (CRE) outbreak occurred in an advanced emergency medical service center [hereafter referred to as the intensive care unit (ICU)] between 2016 and 2017. Aim: Our objective was to evaluate the infection control measures for CRE outbreaks. Methods: CRE strains were detected in 16 inpatients located at multiple sites. Environmental cultures were performed and CRE strains were detected in 3 of 38 sites tested. Pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and detection of β-lactamase genes were performed against 25 CRE strains. Findings: Molecular typing showed the PFGE patterns of two of four Klebsiella pneumoniae strains were closely related and the same MLST (ST2388), and four of five Enterobacter cloacae strains were closely related and same MLST (ST252). Twenty-three of 25 CRE strains harbored the IMP-1 β-lactamase gene and 15 of 23 CRE strains possessed IncFIIA replicon regions. Despite interventions by the infection control team, new inpatients with the CRE strain continued to appear. Therefore, the ICU was partially closed and the inpatients with CRE were isolated, and the ICU staff was divided into two groups between inpatients with CRE and non-CRE strains to avoid cross-contamination. Although the occurrence of new cases dissipated quickly after the partial closure, a few months were required to eradicate the CRE outbreak. Conclusion: Our data suggest that the various and combined measures that were used for infection control were essential in stopping this CRE outbreak. In particular, partial closure to isolate the ICU and division of the ICU staff were effective.
Journal Article
Multi-locus phylogeny and taxonomy of an unresolved, heterogeneous species complex within the genus Golovinomyces (Ascomycota, Erysiphales), including G. ambrosiae, G. circumfusus and G. spadiceus
by
Timur S. Bulgakov
,
Temitope Aroge
,
Uwe Braun
in
28S rDNA
,
Airborne microorganisms
,
Ascomycota
2020
Background
Previous phylogenetic analyses of species within the genus
Golovinomyces
(Ascomycota
,
Erysiphales), based on ITS and 28S rDNA sequence data, revealed a co-evolutionary relationship between powdery mildew species and hosts of certain tribes of the plant family Asteraceae.
Golovinomyces
growing on host plants belonging to the
Heliantheae
formed a single lineage, comprised of a morphologically differentiated complex of species, which included
G. ambrosiae
,
G. circumfusus
, and
G. spadiceus
. However, the lineage also encompassed sequences retrieved from
Golovinomyces
specimens on other Asteraceae tribes as well as other plant families, suggesting the involvement of a plurivorous species. A multilocus phylogenetic examination of this complex, using ITS, 28S, IGS (intergenic spacer),
TUB2
(beta-tubulin), and
CHS1
(chitin synthase I) sequence data was carried out to clarify the discrepancies between ITS and 28S rDNA sequence data and morphological differences. Furthermore, the circumscription of species and their host ranges were emended.
Results
The phylogenetic and morphological analyses conducted in this study revealed three distinct species named, viz., (1)
G. ambrosiae
emend. (including
G. spadiceus
), a plurivorous species that occurs on a multitude of hosts including,
Ambrosia
spp., multiple species of the
Heliantheae
and plant species of other tribes of Asteraceae including the Asian species of
Eupatorium
; (2)
G. latisporus
comb. nov. (≡
Oidium latisporum
), the closely related, but morphologically distinct species confined to hosts of the
Heliantheae
genera
Helianthus
,
Zinnia
, and most likely
Rudbeckia
; and (3)
G. circumfusus
confined to
Eupatorium cannabinum
in Europe.
Conclusions
The present results provide strong evidence that the combination of multi-locus phylogeny and morphological analysis is an effective way to identify species in the genus
Golovinomyces
.
Journal Article
Development and evaluation of a core genome multilocus typing scheme for whole-genome sequence-based typing of Acinetobacter baumannii
by
Prior, Karola
,
Seifert, Harald
,
Higgins, Paul G.
in
Acinetobacter baumannii
,
Acinetobacter baumannii - genetics
,
Acinetobacter baumannii - isolation & purification
2017
We have employed whole genome sequencing to define and evaluate a core genome multilocus sequence typing (cgMLST) scheme for Acinetobacter baumannii. To define a core genome we downloaded a total of 1,573 putative A. baumannii genomes from NCBI as well as representative isolates belonging to the eight previously described international A. baumannii clonal lineages. The core genome was then employed against a total of fifty-three carbapenem-resistant A. baumannii isolates that were previously typed by PFGE and linked to hospital outbreaks in eight German cities. We defined a core genome of 2,390 genes of which an average 98.4% were called successfully from 1,339 A. baumannii genomes, while Acinetobacter nosocomialis, Acinetobacter pittii, and Acinetobacter calcoaceticus resulted in 71.2%, 33.3%, and 23.2% good targets, respectively. When tested against the previously identified outbreak strains, we found good correlation between PFGE and cgMLST clustering, with 0-8 allelic differences within a pulsotype, and 40-2,166 differences between pulsotypes. The highest number of allelic differences was between the isolates representing the international clones. This typing scheme was highly discriminatory and identified separate A. baumannii outbreaks. Moreover, because a standardised cgMLST nomenclature is used, the system will allow inter-laboratory exchange of data.
Journal Article