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PubMed2005

Molecular subtypes and phenotypic expression of Beckwith-Wiedemann syndrome.

Beckwith-Wiedemann Syndrome (BWS) results from mutations or epigenetic events involving imprinted genes at 11p15.5. Most BWS cases are sporadic and uniparental disomy (UPD) or putative imprinting errors predominate in this group. Sporadic cases with putative imprinting defects may be subdivided into (a) those with loss of imprinting (LOI) of IGF2 and H19 hypermethylation and silencing due to a defect in a distal 11p15.5 imprinting control element (IC1) and (b) those with loss of methylation at KvDMR1, LOI of KCNQ1OT1 (LIT1) and variable LOI of IGF2 in whom there is a defect at a more proximal imprinting control element (IC2). We investigated genotype/epigenotype-phenotype correlations in 200 cases with a confirmed molecular genetic diagnosis of BWS (16 with CDKN1C mutations, 116 with imprinting centre 2 defects, 14 with imprinting centre 1 defects and 54 with UPD). Hemihypertrophy was strongly associated with UPD (P<0.0001) and exomphalos was associated with an IC2 defect or CDKN1C mutation but not UPD or IC1 defect (P<0.0001). When comparing birth weight centile, IC1 defect cases were significantly heavier than the patients with CDKN1C mutations or IC2 defect (P=0.018). The risk of neoplasia was significantly higher in UPD and IC1 defect cases than in IC2 defect and CDKN1C mutation cases. Kaplan-Meier analysis revealed a risk of neoplasia for all patients of 9% at age 5 years, but 24% in the UPD subgroup. The risk of Wilms' tumour in the IC2 defect subgroup appears to be minimal and intensive screening for Wilms' tumour appears not to be indicated. In UPD patients, UPD extending to WT1 was associated with renal neoplasia (P=0.054). These findings demonstrate that BWS represents a spectrum of disorders. Identification of the molecular subtype allows more accurate prognostic predictions and enhances the management and surveillance of BWS children such that screening for Wilms' tumour and hepatoblastoma can be focused on those at highest risk.

Alleles↗

PubMed2026

Germline determinants of risk and molecular subtype in young-onset lung cancer.

Young-onset lung cancer is enriched for never-smoking and oncogene-driven tumors, yet its inherited genetic basis remains poorly defined. We performed germline whole-genome sequencing in 251 young-onset lung cancer cases (median age 37), which we jointly analyzed with never-smoking cases (n=196; median age 68) and cancer-free controls (n=1,883). We identified enrichments of rare deleterious coding variants across 55 cancer-related gene sets, including EGFR/ERBB2 signaling and genes implicated by prior lung cancer GWAS. Exome-wide analyses of rare coding variants affirmed TP53 as a penetrant lung cancer predisposition gene (odds ratio [OR]=36.1, p=1.02x10-7) and discovered two novel exome-wide significant tumor subtype-dependent associations: IREB2 in cases with fusion-driven tumors (p=1.39x10-6) and SMAD6 in fusion-negative tumors (p=2.05x10-6). Structural variants contributed distinct risk, with enrichment in constrained, lung-expressed genes (OR=5.79, p=5.8x10-5) and very large germline deletions being markedly enriched in cases with fusion-driven tumors. Polygenic risk scores for lung cancer were inversely correlated with rare variant burden, consistent with additive risk from rare and common variants. Collectively, these findings delineate a complex germline architecture underlying susceptibility and molecular subtype in young-onset lung cancer.

Journal Article↗

PubMed2004

Research note: Molecular subtyping of Salmonella enterica serovar Tshiongwe recently isolated in Malaysia during 2001-2002.

Pulsed field gel electrophoresis (PFGE) and antimicrobial susceptibility analysis were undertaken on twenty-three strains of Salmonella enterica serovar Tshiongwe, an unusual serovar, which recently emerged in Malaysia. Antimicrobial susceptibility analysis showed that all the strains were sensitive to ampicilin, chloramphenicol, cotrimoxazole, and kanamycin. Twenty (87%) and 8 (3.5%) strains had resistance to tetracycline and streptomycin respectively. PFGE analysis subtyped 23 strains into 10 profiles (Dice coefficient of similarity, F = 0.7-1.0). The predominant profile, X1 was found in both clinical and environmental isolates and was widely distributed in different parts of Malaysia during the study period. In addition, isolates recovered from food, a hand-towel, apron and the surface of a table-top in one particular location had unique, indistinguishable profiles (X4/4a) and identical antibiograms. Similarly, isolates from cooked meat and a chopping board had PFGE profiles similar to some human isolates. These probably indicated cross-contamination and poor hygiene in food practices, hence contributing to Salmonellosis. Factors causing the emergence of this rare Salmonella serovar being responsible for food poisoning episodes during the study period remained unclear. The study reiterated the usefulness and versatility of PFGE in the molecular subtyping of this rare Salmonella serovar in Malaysia.

Anti-Bacterial Agents↗

PubMed2004

Molecular Subtyping and Tracking of Listeria monocytogenes in Latin-Style Fresh-Cheese Processing Plants.

Latin-style fresh cheeses, which have been linked to at least 2 human listeriosis outbreaks in the United States, are considered to be high-risk foods for Listeria monocytogenes contamination. We evaluated L. monocytogenes contamination patterns in 3 Latin-style fresh-cheese processing plants to gain a better understanding of L. monocytogenes contamination sources in the manufacture of these cheeses. Over a 6-mo period, 246 environmental samples were collected and analyzed for L. monocytogenes using both the Food and Drug Administration (FDA) method and the Biosynth L. monocytogenes detection system (LMDS). Finished cheese samples from the same plants (n = 111) were also analyzed by the FDA method, which was modified to include L. monocytogenes plating medium (LMPM) and the L. monocytogenes confirmatory plating medium (LMCM) used in the LMDS method. Listeria monocytogenes was detected in 6.3% of cheese and 11.0% of environmental samples. Crates, drains, and floor samples showed the highest contamination rates, with 55.6, 30.0, and 20.6% L. monocytogenes positive samples, respectively. Finished products and food contact surfaces were positive in only one plant. The FDA method showed a higher sensitivity than the LMDS method for detection of L. monocytogenes from environmental samples. The addition of LMPM and LMCM media did not further enhance the performance of the FDA method for L. monocytogenes detection from finished products. Molecular subtyping (PCR-based allelic analysis of the virulence genes actA and hly and automated ribotyping) was used to track contamination patterns. Ribotype DUP-1044A, which had previously been linked to a 1998 multistate human listeriosis outbreak in the United States, was the most commonly identified subtype (20/36 isolates) and was isolated from 2 plants. This ribotype was persistent and widespread in one factory, where it was also responsible for the contamination of finished products. We hypothesize that this ribotype may represent a clonal group with a specific ability to persist in food processing environments. While previous listeriosis outbreaks were linked to Latin-style fresh cheeses made from unpasteurized milk, the presence of this organism in pasteurized cheese products illustrates that persistent environmental contamination also represents an important source of finished product contamination.

Cheese↗

PubMed2026

Molecular subtyping of adrenocortical carcinoma reveals distinct subtypes with prognostic and therapeutic implications.

Adrenocortical carcinoma (ACC) is a rare but aggressive malignancy with poor survival and limited treatment options. To comprehensively characterize its molecular landscape and identify clinically relevant subtypes, we performed an integrated genomic analysis - including whole-exome sequencing, RNA sequencing, and copy number variation profiling - on 61 Chinese patients with ACC. We identified recurrent mutations in TP53 (25%), CTNNB1 (15%), ZNRF3 (10%), and MEN1 (8%). Unsupervised clustering of transcriptomic data revealed four distinct molecular subtypes: cortisol-driven (CD, 14%), immune-suppressed (IS, 40%), cell cycle-altered (CCA, 22%), and immunomodulatory (IM, 24%). The CD subtype exhibited steroidogenic pathway activation; the IS subtype showed T cell receptor downregulation and the worst disease-free survival; the CCA subtype was marked by chromosomal instability and cell cycle gene overexpression; and the IM subtype displayed enriched immune signaling and favorable outcomes. Copy number analysis further uncovered focal amplifications (e.g. TERT, CDK4) and HLA-II deletions. This study establishes a novel molecular classification of ACC, providing a framework for subtype-specific therapeutic strategies, such as CDK4/6 inhibition for CCA and immunotherapy for IM tumors, while highlighting the clinical challenges of immune-cold IS tumors.

Humans↗

PubMed2001

Molecular subtyping of Treponema pallidum in an Arizona County with increasing syphilis morbidity: use of specimens from ulcers and blood.

A molecular-based subtyping system for Treponema pallidum was used during an investigation of increasing syphilis in Maricopa County, Arizona. Genital ulcer or whole blood specimens from patients with syphilis were assayed by a polymerase chain reaction (PCR) amplification of a T. pallidum DNA polymerase I gene. Positive specimens were typed on the basis of PCR amplification of 2 variable genes. In all, 41 (93%) of 44 of ulcer specimens and 4 (27%) of 15 blood specimens yielded typeable T. pallidum DNA. Twenty-four (53%) of 45 specimens were subtype 14f; other subtypes identified included 4f, 4i, 5f, 12a, 12f, 14a, 14d, 14e, and 14i. Only 2 specimens were from epidemiologically linked patients. This investigation demonstrates that multiple subtypes of T. pallidum can be found in an area with high syphilis morbidity, although 1 subtype (14f) was predominant. Four typeable specimens were from blood, a newly identified specimen source for subtyping.

Arizona↗

PubMed1997

Molecular subtyping of human T-lymphotropic virus type I (HTLV-I) by a nested polymerase chain reaction-restriction fragment length polymorphism analysis of the envelope gene: two distinct lineages of HTLV-I in Taiwan.

The major type of human T-lymphotropic virus type I (HTLV-I), generally referred to as the cosmopolitan type, has been grouped into three subtypes (A, B, and C) by phylogenetic analysis of the long terminal repeat sequences of the viral genome. Twelve subtype-specific nucleotide variations have been deduced by comparison between the envelope (env) sequences of 16 HTLV-I strains with defined subtypes and 9 Taiwanese HTLV-I strains. To gain further insights into the molecular epidemiology of HTLV-I and the origin of this virus in Taiwan, a rapid method of identification for the cosmopolitan subtypes was developed by using a nested polymerase chain reaction (PCR) and subsequent restriction fragment length polymorphism (RFLP) studies using the two subtype B-specific and four subtype C-specific nucleotides located within the positions 5708 to 6320 of the envgene. The nested PCR-RFLP method was used to subtype HTLV-I from four virus-positive cell lines derived from 1 Japanese and 3 North American patients, as well as 41 blood-unrelated Taiwan Chinese. The sequences of PCR products were determined and the six positions of subtype-specific nucleotide variations were examined. The sequence data completely supported the subtyping data via the nested PCR-RFLP method. The results demonstrated that, as is the case in Japan, at least two distinct cosmopolitan subtypes (A and B) of HTLV-I were present in Taiwan, but the more prevalent subtype in Taiwan is A in contrast to subtype B in Japan. Furthermore, rapid subtyping could facilitate molecular epidemiological studies of HTLV-I infection and linkage between HTLV-I subtypes and virus-associated diseases.

Base Sequence↗

PubMed2026

First identification and molecular subtyping of Blastocystis spp. in donkeys in Aksaray province, Türkiye.

Blastocystis is a common intestinal protist worldwide that can infect humans and animals. Although its molecular epidemiology in Türkiye is mostly focused primarily on humans and livestock, equids have received limited attention despite their traditional roles and frequent contact with humans and other animals in rural environments. This study aimed to determine the molecular prevalence and subtype (ST) distribution of Blastocystis spp. in donkeys in Aksaray Province, providing the first molecular data on donkeys in Türkiye. A total of 182 fresh fecal samples were collected from donkeys in nine villages within Aksaray province. Genomic DNA was extracted, and the small subunit ribosomal RNA (SSU rRNA) gene fragment of Blastocystis spp. was amplified via PCR analysis. Positive isolates were sequenced bidirectionally for identification and subsequent phylogenetic analysis of Blastocystis in donkeys. The overall molecular prevalence of Blastocystis spp. in donkeys was 4.4% (8/182). The infection rate was higher in young donkeys (under 3 years old; 8.33%) than in adults (3 years or older; 2.46%). However, this difference was not statistically significant. Sequence analysis of the positive PCR products revealed the presence of one known livestock-specific subtype, ST10. Phylogenetic analysis showed that the ST10 isolates characterized in this study clustered with isolates identified from different hosts. This study provides the first molecular data on Blastocystis presence in donkeys in Türkiye. The exclusive detection of ST10 suggests potential cross-species transmission, likely facilitated by the traditional practice of co-housing donkeys with other animals in confined barns. These findings indicate that donkeys may contribute to Blastocystis transmission, underscoring the importance of a "One Health" approach in future epidemiological surveillance.

Animals↗

PubMed2003

A combined comparative genomic hybridization and expression microarray analysis of gastric cancer reveals novel molecular subtypes.

Comparative genomic hybridization (CGH), microsatellite instability (MSI) assays, and expression microarrays were used to molecularly subclassify a common set of gastric tumor samples. We identified a number of novel genomic aberrations associated with gastric cancer and discovered that gastric tumors could be grouped by their expression profiles into three broad classes: "tumorigenic," "reactive," and "gastric-like." Patients with gastric-like tumors exhibited a significantly better overall survival than patients belonging to the other two classes (P < 0.05). A novel supervised learning methodology for multiclass prediction was used to identify optimal predictor gene sets that accurately predicted the class of an unknown tumor sample. These predictor sets may prove useful in the development of new diagnostic applications for gastric cancer staging and prognostication.

Adenocarcinoma↗

PubMed2005

Integrated array-comparative genomic hybridization and expression array profiles identify clinically relevant molecular subtypes of glioblastoma.

Glioblastoma, the most aggressive primary brain tumor in humans, exhibits a large degree of molecular heterogeneity. Understanding the molecular pathology of a tumor and its linkage to behavior is an important foundation for developing and evaluating approaches to clinical management. Here we integrate array-comparative genomic hybridization and array-based gene expression profiles to identify relationships between DNA copy number aberrations, gene expression alterations, and survival in 34 patients with glioblastoma. Unsupervised clustering on either profile resulted in similar groups of patients, and groups defined by either method were associated with survival. The high concordance between these separate molecular classifications suggested a strong association between alterations on the DNA and RNA levels. We therefore investigated relationships between DNA copy number and gene expression changes. Loss of chromosome 10, a predominant genetic change, was associated not only with changes in the expression of genes located on chromosome 10 but also with genome-wide differences in gene expression. We found that CHI3L1/YKL-40 was significantly associated with both chromosome 10 copy number loss and poorer survival. Immortalized human astrocytes stably transfected with CHI3L1/YKL-40 exhibited changes in gene expression similar to patterns observed in human tumors and conferred radioresistance and increased invasion in vitro. Taken together, the results indicate that integrating DNA and mRNA-based tumor profiles offers the potential for a clinically relevant classification more robust than either method alone and provides a basis for identifying genes important in glioma pathogenesis.

Adipokines↗

PubMed1992

Photoaffinity labeling of the somatostatin receptor: identification of molecular subtypes.

Pharmacological studies have suggested that the somatostatin (SS) receptor is heterogeneous and may exhibit subtypes selective for SS-14 and SS-28. Whether this heterogeneity can be explained by separate molecular forms of the receptor protein is unclear. In the present study, we have developed a novel photosensitive azido derivative of the octapeptide SS analog Tyr3 SMS (EE 581) and used it as a photoaffinity probe to characterize the molecular components of the SS receptor in five receptor positive tissues (normal rat brain, pituitary, pancreas, and adrenal cortex, and mouse AtT-20 pituitary tumor cells). [125I]EE-581 labeled specific high affinity binding sites in all these tissues (Kd range 1.3-1.67 nM). Photoaffinity labeled membrane SS receptors were analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis followed by autoradiography. Three specifically labeled SS receptor proteins of 80 kilodaltons (kDa), 58 kDa, and 32 kDa were identified and exhibited a tissue-specific distribution. The 58 kDa species was the exclusive form in pancreas, adrenal cortex, and AtT-20 cells and the dominant form in brain. The 32 kDa receptor protein was expressed as a minor form (ratio of 58 kDa:32 kDa 3:1), exclusively in brain. The 80 kDa receptor was found only in the pituitary where it occurred as the sole SS receptor species. Competition experiments showed that the 58 kDa and 32 kDa receptor proteins in brain reacted with SS-14 greater than SS-28; in contrast, the 58 kDa protein in AtT-20 cells bound SS-28 greater than SS-14 suggesting the existence of distinct subtypes of the 58 kDa receptor in these two tissues. These data represent the first systematic evaluation of the molecular forms of SS receptor proteins by photoaffinity labeling in different target tissues and provide direct evidence for molecular heterogeneity and SS-14/SS-28 selectivity; a major 58 kDa protein present in most tissues, an additional 32 kDa protein uniquely expressed in brain, and an 80 kDa protein exclusive to the normal pituitary.

Adrenal Glands↗

PubMed2000

The alpha 1a and alpha 1b-adrenergic receptor subtypes: molecular mechanisms of receptor activation and of drug action.

In this chapter we summarize some aspects of the structure-functional relationship of the alpha 1a and alpha 1b-adrenergic receptor subtypes related to the receptor activation process as well as the effect of different alpha-blockers on the constitutive activity of the receptor. Molecular modeling of the alpha 1a and alpha 1b-adrenergic receptor subtypes and computational simulation of receptor dynamics were useful to interpret the experimental findings derived from site directed mutagenesis studies.

Animals↗

PubMed1997

Molecular epidemiology of 58 new African human T-cell leukemia virus type 1 (HTLV-1) strains: identification of a new and distinct HTLV-1 molecular subtype in Central Africa and in Pygmies.

To gain new insights on the origin, evolution, and modes of dissemination of human T-cell leukemia virus type I (HTLV-1), we performed a molecular analysis of 58 new African HTLV-1 strains (18 from West Africa, 36 from Central Africa, and 4 from South Africa) originating from 13 countries. Of particular interest were eight strains from Pygmies of remote areas of Cameroon and the Central African Republic (CAR), considered to be the oldest inhabitants of these regions. Eight long-term activated T-cell lines producing HTLV-1 gag and env antigens were established from peripheral blood mononuclear cell cultures of HTLV-1 seropositive individuals, including three from Pygmies. A fragment of the env gene encompassing most of the gp21 transmembrane region was sequenced for the 58 new strains, while the complete long terminal repeat (LTR) region was sequenced for 9 strains, including 4 from Pygmies. Comparative sequence analyses and phylogenetic studies performed on both the env and LTR regions by the neighbor-joining and DNA parsimony methods demonstrated that all 22 strains from West and South Africa belong to the widespread cosmopolitan subtype (also called HTLV-1 subtype A). Within or alongside the previously described Zairian cluster (HTLV-1 subtype B), we discovered a number of new HTLV-1 variants forming different subgroups corresponding mainly to the geographical origins of the infected persons, Cameroon, Gabon, and Zaire. Six of the eight Pygmy strains clustered together within this Central African subtype, suggesting a common origin. Furthermore, three new strains (two originating from Pygmies from Cameroon and the CAR, respectively, and one from a Gabonese individual) were particularly divergent and formed a distinct new phylogenetic cluster, characterized by specific mutations and occupying in most analyses a unique phylogenetic position between the large Central African genotype (HTLV-1 subtype B) and the Melanesian subtype (HTLV-1 subtype C). We have tentatively named this new HTLV-1 genotype HTLV-1 subtype D. While the HTLV-1 subtype D strains were not closely related to any known African strain of simian T-cell leukemia virus type 1 (STLV-1), other Pygmy strains and some of the new Cameroonian and Gabonese HTLV-1 strains were very similar (>98% nucleotide identity) to chimpanzee STLV-1 strains, reinforcing the hypothesis of interspecies transmission between humans and monkeys in Central Africa.

Africa, Central↗

PubMedDate not supplied

Long-term survivors of glioblastoma: statistical aberration or important unrecognized molecular subtype?

Unlike most patients with glioblastoma multiforme who survive less than a year, approximately 2% have an unusually long survival after diagnosis and contemporary treatment (> or = 3 or more years); rarely, the disease appears to be "cured." Understanding these rare patients may tell us something important about the biology of glioblastoma multiforme. Patients who are young, have good performance status, and receive multimodalitytherapy (i.e., surgical resection, radiotherapy, and adjuvant chemotherapy) are more likely to have a long survival than older patients with poor performance status who are treated identically. However, the aforementioned clinical characteristics of long-term survivors do not explain why most patients with glioblastoma multiforme who have this same constellation of favorable features succumb to the disease relatively quickly. "Glioblastoma multiforme" is a group of diseases, one subtype of which behaves in a more indolent fashion, or responds well to current therapies, or both. In this review, we summarize the molecular characteristics of glioblastoma multiforme and pay special attention to molecular predictors of survival outcome, an area of research that is still in its infancy. We conclude by suggesting a translational research strategy that is aimed at uncovering the molecular signatures of long survivorship.

Age Factors↗

PubMed2002

Gene expression profiling defines molecular subtypes of classical Hodgkin's disease.

Although the prognosis of Hodgkin's disease is relatively good, around 20% of patients do not benefit from current therapies and succumb to their disease. A large-scale molecular characterization of disease might help improve HD management. Using cDNA arrays, we studied the mRNA expression levels of approximately 1000 selected genes in 34 benign and malignant lymphoid samples including 21 classical Hodgkin's disease (HD) tissue samples. Hierarchical clustering identified three main molecular groups of HD tumours relevant with respect to histology and clinical outcome (response to therapy and survival). Samples from all bad outcome HD (BOHD) patients clustered in one group whereas the two other groups contained most good outcome HD (GOHD) cases. The nodular sclerosis GOHD samples overexpressed genes involved in apoptotic induction and cell signalling, including cytokines, while the BOHD samples were characterized by the upregulation of genes involved in fibroblast activation, angiogenesis, extracellular matrix remodelling, cell proliferation, and the downregulation of tumour suppressor genes. Our results establish a molecular taxonomy of HD correlating with response to therapy and clinical outcome, thereby suggesting the possibility of improving the current prognostic classification.

Apoptosis↗

PubMed2005

Molecular subtypes of bladder cancer: Jekyll and Hyde or chalk and cheese?

Cancer of the bladder shows divergent clinical behaviour following diagnosis and it has been proposed that two major groups of tumours exist that develop via different molecular pathways. Low-grade, non-invasive papillary tumours recur frequently, but patients with these tumours do not often suffer progression of disease to muscle invasion. In contrast, tumours that are invading muscle at diagnosis are aggressive and associated with significant mortality. Molecular studies have identified distinct genetic, epigenetic and expression changes in these groups. However, it is not yet clear whether there is direct progression of low-grade superficial tumours to become invasive (a Jeckell and Hyde scenario) or whether in those patients who apparently progress from one form of the disease to the other, different tumour clones are involved and that the two tumour groups are mutually exclusive ('chalk and cheese'). If the latter is true, then attempts to identify molecular markers to predict progression of low-grade superficial bladder tumours may be fruitless. Similarly, it is not clear whether other subgroups of tumours exist that arise via different molecular pathways. There is now a large amount of molecular information about bladder cancer that facilitates examination of these possibilities. Some recent studies provide evidence for the existence of at least one further group of tumours, high-grade superficial papillary tumours, which may develop via a distinct molecular pathway. Patients with such tumours do show increased risk of disease progression and for these there may exist a real progression continuum from non-invasive to invasive. If this is the case, definition of the molecular signature of this pathway and improved understanding of the biological consequences of the events involved will be pivotal in disease management.

Cell Transformation, Neoplastic↗

PubMed1999

Molecular subtyping of Staphylococcus aureus isolates from cases of bovine mastitis in Brazil.

Sixty-six isolates of Staphylococcus aureus obtained from milk samples of dairy cows suffering from subclinical mastitis in southern Brazil were analysed by five different molecular typing methods. These included the analysis of plasmid profiles, the analysis of coagulase (coa) gene polymorphisms by PCR amplification of the 3' terminal region of the coa gene, the PCR-based detection of polymorphisms in the X region of the protein A gene (spa), the PCR-directed analysis of variations in the spacer region between 16S and 23S rRNA, and the comparison of pulsed-field gel electrophoretically separated genomic SmaI fragment patterns. The molecular typing methods were supplemented with the biochemical characterization of the isolates and the determination of their in-vitro susceptibility to 14 different antibiotics. All genotypic and phenotypic typing methods were analyzed for their ability to discriminate between the isolates. Macrorestriction analysis proved to be the most discriminatory single method (D = 0.96) followed by rRNA spacer typing (D = 0.85), coa PCR (D = 0.82), and spa PCR (D = 0.80).

Animals↗

PubMed2006

[Use of molecular subtyping methods to investigate two nosocomial outbreaks due to Salmonella Livingstone in Sfax hospital, Tunisia].

OBJECTIVE: The aim of the study was to investigate two nosocomial outbreaks due to Salmonella Livingstone in a pediatric ward in Sfax hospital using molecular typing techniques. MATERIALS AND METHODS: We included 84 strains of S. Livingstone isolated from patients hospitalized in a pediatric ward between November 1999 through August 2002 in addition to one environmental sample. Three epidemiological unrelated strains of S. Livingstone were also tested. The molecular typing techniques were: plasmid analysis, enterobacterial repetitive intergenic consensus (ERIC-PCR), random amplification of polymorphic DNA (RAPD-PCR) and pulsed field gel electrophoresis (PFGE). RESULTS: The plasmid analysis and the ERIC-PCR generated a similar profile for outbreak isolates including the environmental sample while the epidemiologically unrelated strains demonstrated distinct patterns. The RAPD-PCR applied on 20 strains showed three patterns but one profile was predominating. All the strains isolate of S. Livingstone, except the veterinary strain, could not be typed by PFGE. CONCLUSION: Using the molecular typing techniques, we showed that these two outbreaks in the pediatric ward were due to the clonal spread of a single strain of S. Livingstone. The identification of the source of contamination and the improvement of hygiene conditions are required.

Bacterial Typing Techniques↗