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Clinical Strains (clinical + strain)

Distribution by Scientific Domains

Medical Sciences	57%
Life Sciences	42%

Selected Abstracts

Release of monocyte chemoattractant protein (MCP)-1 by a human alveolar epithelial cell line in response to Mycobacterium avium

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2000
Savita P. Rao
Abstract Clinical strains of Mycobacterium avium isolated from patients with acquired immunodeficiency syndrome, but not a non-clinical laboratory strain (ATCC 25291), were found to stimulate the human alveolar epithelial cell line A549, to produce monocyte chemoattractant protein (MCP)-1. A549 cells were also found to produce elevated levels of MCP-1 in response to sonicates of the clinical strains of M. avium, and surprisingly, the non-clinical strain as well. However, sonic extracts of the clinical strains were found to induce significantly higher levels of MCP-1 production compared to extracts of the non-clinical strain (P<0.001). These data suggest the existence of strain-related differences in antigen expression by M. avium. The clinical and non-clinical strains of M. avium were found to attach and invade, but not replicate in A549 cells indicating that MCP-1 production by A549 cells does require the presence of viable, replicating organisms. Activation of alveolar epithelial cells by exposure to M. avium resulting in the production of chemokines which recruit inflammatory cells to the site of infection may be an important regulatory pathway for the activation of pulmonary host defense. [source]

PDR16 -mediated azole resistance in Candida albicans

MOLECULAR MICROBIOLOGY, Issue 6 2006
Saloua Saidane
Summary Many Candida albicans azole-resistant (AR) clinical isolates overexpress the CDR1 and CDR2 genes encoding homologous multidrug transporters of the ATP-binding cassette family. We show here that these strains also overexpress the PDR16 gene, the orthologue of Saccharomyces cerevisiae PDR16 encoding a phosphatidylinositol transfer protein of the Sec14p family. It has been reported that S. cerevisiae pdr16, mutants are hypersusceptible to azoles, suggesting that C. albicans PDR16 may contribute to azole resistance in these isolates. To address this question, we deleted both alleles of PDR16 in an AR clinical strain overexpressing the three genes, using the mycophenolic acid resistance flipper strategy. Our results show that the homozygous pdr16,/pdr16, mutant is approximately twofold less resistant to azoles than the parental strain whereas reintroducing a copy of PDR16 in the mutant restored azole resistance, demonstrating that this gene contributes to the AR phenotype of the cells. In addition, overexpression of PDR16 in azole-susceptible (AS) C. albicans and S. cerevisiae strains increased azole resistance by about twofold, indicating that an increased dosage of Pdr16p can confer low levels of azole resistance in the absence of additional molecular alterations. Taken together, these results demonstrate that PDR16 plays a role in C. albicans azole resistance. [source]

Zeocin resistance as a dominant selective marker for transformation and targeted gene deletions in Candida glabrata

MYCOSES, Issue 6 2006
Alex J. Alderton
Summary Many of the genetic tools used to generate gene knockouts in Candida glabrata exploit auxotrophic markers but this is not suitable for use with clinical strains. Antibiotic resistance markers, however, allow one to target genes to be deleted without any prior genetic manipulation of clinical isolates. Such antibiotic selection markers have been widely reported for the manipulation of Saccharomyces cerevisiae. However, very few antibiotic resistance markers have been shown to be useful in C. glabrata. Here, we report the use of Zeocin resistance (ZeoR), encoded by the ble gene from Streptoalloteichus hindustanus, as a new positive selection marker for the genetic manipulation of C. glabrata including clinical strains that we show are significantly more sensitive to Zeocin than to G418. The potential of the ZeoR marker for targeted gene disruption in C. glabrata was confirmed by constructing deletions of the ADE2 in both a laboratory and a clinical strain of C. glabrata, using both short (90 bp) and long (400 bp) homology cassettes. [source]

The rhizosphere as a reservoir for opportunistic human pathogenic bacteria

ENVIRONMENTAL MICROBIOLOGY, Issue 11 2005
Gabriele Berg
Summary During the last years, the number of human infections caused by opportunistic pathogens has increased dramatically. One natural reservoir of opportunistic pathogens is the rhizosphere, the zone around roots that is influenced by the plant. Due to a high content of nutrients, this habitat is a ,microbial hot-spot', where bacterial abundances including those with strong antagonistic traits are enhanced. Various bacterial genera, including Burkholderia, Enterobacter, Herbaspirillum, Ochrobactrum, Pseudomonas, Ralstonia, Staphylococcus and Stenotrophomonas, contain root-associated strains that can encounter bivalent interactions with both plant and human hosts. Mechanisms responsible for colonization of the rhizosphere and antagonistic activity against plant pathogens are similar to those responsible for colonization of human organs and tissues, and pathogenicity. Multiple resistances against antibiotics are not only found with clinical strains but also with strains isolated from the rhizosphere. High competition, the occurrence of diverse antibiotics in the rhizosphere, and enhanced horizontal gene transfer rates in this microenvironment appear to contribute to the high levels of natural resistances. While opportunistic bacteria from the rhizosphere have some properties in common, each of these emerging pathogens has its own features, which are discussed in detail for Burkholderia, Ochrobactrum and Stenotrophomonas. [source]

Release of monocyte chemoattractant protein (MCP)-1 by a human alveolar epithelial cell line in response to Mycobacterium avium

Optimisation of AP,PCR fingerprinting discriminatory power for clinical isolates of Pseudomonas aeruginosa

FEMS MICROBIOLOGY LETTERS, Issue 1 2003
Waldemar Da, browski
Abstract Recently methods based on analysis of arbitrarily amplified target sites of microorganism genomes have been extensively applied in microbiological studies. The range of their applications is limited by problems with discrimination and reproducibility resulting from lack of standardised and reliable methods of optimisation. By orthogonal-array optimisation most advantageous and optimal parameters for highly discriminatory primers (CagA2+CMVin2) were selected and efficient AP,PCR (arbitrarily primed-polymerase chain reaction) fingerprinting conditions for Pseudomonas aeruginosa isolates were set up. Stable and multiplex amplicon profiles obtained in this study revealed high level of intraspecies DNA polymorphism among 20 analysed clinical strains of P. aeruginosa proving optimised AP,PCR fingerprinting to be useful in epidemiological typing of the species. [source]

Dynamics of in vitro acquisition of resistance by Candida parapsilosis to different azoles

FEMS YEAST RESEARCH, Issue 4 2009
Ana Teresa Pinto e Silva
Abstract Candida parapsilosis is a common isolate from clinical fungal infectious episodes. Resistance of C. parapsilosis to azoles has been increasingly reported. To analyse the development of resistance in C. parapsilosis, four azole-susceptible clinical strains and one American Type Culture Collection type strain were cultured in the presence of fluconazole, voriconazole and posaconazole at different concentrations. The isolates developed variable degrees of azole resistance according to the antifungal used. Fluconazole was the fastest inducer while posaconazole was the slowest. Fluconazole and voriconazole induced resistance to themselves and each other, but not to posaconazole. Posaconazole induced resistance to all azoles. Developed resistance was stable; it could be confirmed after 30 days of subculture in drug-free medium. Azole-resistant isolates revealed a homogeneous population structure; the role of azole transporter efflux pumps was minor after evaluation by microdilution and cytometric assays with efflux pump blockers (verapamil, ibuprofen and carbonyl cyanide 3-chloro-phenylhydrazone). We conclude that the rapid development of azole resistance occurs by a mechanism that might involve mutation of genes responsible for ergosterol biosynthesis pathway, stressed by exposure to antifungals. [source]

Distribution of type III secretion systems in Vibrio parahaemolyticus from the northern Gulf of Mexico

JOURNAL OF APPLIED MICROBIOLOGY, Issue 3 2010
N.F. Noriea III
Abstract Aims:, Two well-characterized Vibrio parahaemolyticus pathogenicity factors , thermostable direct haemolysin (TDH) and TDH - related haemolysin , are produced by strains containing the tdh and trh genes, respectively. Most strains of V. parahaemolyticus contain two nonredundant type III secretion systems (T3SS), T3SS1 and T3SS2, both of which contribute to pathogenicity. Furthermore, a recent study has revealed two distinct lineages of the V. parahaemolyticus T3SS2: T3SS2, and T3SS2,. The aim of this study was to determine the incidence of these pathogenicity factors in environmental isolates of V. parahaemolyticus. Methods and Results:, We collected 130 V. parahaemolyticus isolates (TCBS agar) containing tdh and/or trh (determined by colony hybridization) from sediment, oyster and water in the northern Gulf of Mexico and screened them and 12 clinical isolates (PCR and agarose gel electrophoresis) for pathogenicity factors tdh, trh, T3SS1, T3SS2, and T3SS2,. The majority of potential pathogens were detected in the sediment, including all tdh,/trh+ isolates. T3SS2, components were detected in all tdh+/trh, isolates and zero of 109 trh+ isolates. One T3SS2, gene, vopB2, was found in all tdh+/trh, clinical strains but not in any of the 130 environmental strains. Fluorescence in situ hybridization adapted for individual gene recognition (RING-FISH) was used to confirm the presence/absence of vopB2. T3SS2, was found in all tdh,/trh+ isolates and in no tdh+/trh, isolates. Conclusions:, The combination of haemolysins found in each isolate consistently corresponded to the presence and type of T3SS detected. The vopB2 gene may represent a novel marker for identifying increased virulence among strains. Significance and Impact of the Study:, This is the first study to confirm the presence of T3SS2, genes in V. parahaemolyticus strains isolated from the Gulf of Mexico and one of the few that examines the distribution and co-existence of tdh, trh, T3SS1, T3SS2, and T3SS2, in a large collection of environmental strains. [source]

Typing of Listeria monocytogenes strains isolated in Italy by inlA gene characterization and evaluation of a new cost-effective approach to antisera selection for serotyping

JOURNAL OF APPLIED MICROBIOLOGY, Issue 5 2010
M. Tamburro
Abstract Aims:, In this study, 105 Listeria monocytogenes strains isolated from humans, foods and environmental samples were characterized using several typing methods. Moreover, serotyping procedure was evaluated, and a cost-effective methodological approach based on preliminary PCRs screening was proposed. Methods and Results:, The isolates were analysed by conventional serotyping, multiplex-PCRs for serogroup and lineage identification and PCR,RFLP of inlA gene to identify potentially noninvasive L. monocytogenes. Among the strains, only the serotypes 1/2a, 1/2c, 1/2b, 4b and 3a were identified. The isolates were classified into serogroups I (58·10%), II (22·85%), III (12·38%) and IV (6·67%). Among clinical strains, lineage I was more represented (68·75%) than lineage II; whereas, lineage II was more associated with food (90·24%) and environmental (85·72%) isolates. Most of food (89·02%) and environmental (85·71%) isolates were classified into truncated InlA profiles, whereas the 93·75% of clinical strains were associated with a complete form of the protein. Conclusion:, Molecular techniques were sensitive and specific for classifying strains into serogroup and lineage and in agreement with the serotyping. Moreover, a preliminary PCRs-based screening was proposed to select only the necessary antisera by a flow chart; this methodological approach allows cost saving up to 42%. Our results further suggest the role of InlA protein in human listeriosis, particularly in immunocompetent individuals, and a correlation between truncated protein and serotype. Significance and Impact of the Study:, This study further validates molecular methods for L. monocytogenes analysis and proposed a new cost-effective approach for serotyping. It could help to improve a national surveillance network for L. monocytogenes infections in Italy. [source]

Human laminin-332 degradation by Candida proteinases

JOURNAL OF ORAL PATHOLOGY & MEDICINE, Issue 6 2008
P. Pärnänen
Background:, Human laminin-332 (Lm-332) degradation by 12 Candida strains and effects of synthetic proteinase inhibitors [Ilomastat (ILM), EDTA, chemically modified tetracycline-3(CMT-3), CMT-308, synthetic peptide CTT-2, and Pefabloc] were studied. Materials and methods:, Laminin-332 was incubated with sonicated cell fractions and 10 times concentrated cell-free fractions of reference and clinical strains of C. albicans, C. dubliniensis, C. guilliermondii, C. glabrata, C. krusei, and C. tropicalis. Proteolysis, pH effects, and inhibitors were analyzed by fluorography and zymography. Results:, Cell fractions of all species except C. guilliermondii and cell-free fractions of C. albicans, and C. dubliniensis showed 20,70 kDa gelatinases at pH 5.0 and 6.0. At pH 7.6, C. glabrata, C. krusei, and C. tropicalis cell fractions and C. tropicalis cell-free fractions showed 55,70 kDa gelatinases. CMT-3, CMT-308, and CTT-2 inhibited Candida gelatinases slightly better than Pefabloc, ILM, and EDTA. No Candida fractions degraded Lm-332 at pH 7.6, but at pH 5.0, 100 kDa bands were generated by cell fractions of C. dubliniensis and C. tropicalis; C. albicans and C. glabrata clinical strains; and C. guilliermondii reference strain. C. krusei reference strain yielded three 100,130 kDa bands. C. albicans, C. dubliniensis, and C. tropicalis reference and clinical strain's cell-free fractions generated 100 kDa band. Conclusions:, Laminin-332 degradation is pH-dependent and differences exist between studied Candida strains. Lm-332 degradation can exert functional disturbances on basement membrane integrity, possibly aiding Candida cell invasion into tissues. Certain synthetic matrix metalloproteinase inhibitors (CMTs, CTT) can inhibit Candida proteinases and may be therapeutically useful in future. [source]

Genotypic characterization of hospital Enterococcus faecalis strains using multiple-locus variable-number tandem-repeat analysis

LETTERS IN APPLIED MICROBIOLOGY, Issue 1 2009
E. Wa, ecka
Abstract Aims:, The level of genetic diversity and relationships between the specific genotypes and the distribution of virulence determinants among Enterococcus faecalis strains isolated from patients hospitalized in different wards of two hospitals were investigated. Methods and Results:, Fifty-six clinical strains of E. faecalis, isolated from patients hospitalized in the period of 1999,2004 in several wards in Wroc,aw (Poland), were analysed by multiple-locus variable-number tandem-repeat analysis (MLVA). Analysis of seven genomic loci identified 40 novel genotypes among the analysed E. faecalis strains, with two major genomic groups, designated I and II, distinguished at a cut-off of 35%. With a similarity cut-off of 85·7%, the genotypes could be combined into 12 clusters (C1,C12), containing at least two isolates. The remaining 18 MLVA types were represented by a single isolate. Conclusions:, Based on the data obtained by MLVA, it was found that (i) many E. faecalis isolates recovered from patients from the wards whose location allowed the potential transmission of micro-organisms, belonged to closely related MLVA types and (ii) possible relationships between specific E. faecalis genotype and the virulence factors lipase, haemolysin and esp gene can exist. Significance and Impact of the Study:, Our study confirms that MLVA is a suitable method for the epidemiological study of E. faecalis and for the first time shows possible relationships between specific genotypes and such virulence determinants, i.e. lipase, haemolysin and esp gene. [source]

A small outbreak of listeriosis potentially linked to the consumption of imitation crab meat

LETTERS IN APPLIED MICROBIOLOGY, Issue 2 2000
J.M. Farber
A small outbreak of listeriosis involving two previously healthy adults occurred in Ontario. Food samples obtained from the refrigerator of the patients included imitation crab meat, canned black olives, macaroni and vegetable salad, spaghetti sauce with meatballs, mayonnaise and water. All of the samples except the water contained Listeria monocytogenes. The three most heavily contaminated samples were the imitation crab meat, the olives and the salad which contained 2·1 × 109, 1·1 × 107 and 1·3 × 106 cfu g,1, respectively. L. monocytogenes serotype 1/2b was isolated from the patients, as well as from the opened and unopened imitation crab meat. Molecular typing of the isolates by both randomly amplified polymorphic DNA (RAPD) and pulsed-field gel electrophoresis (PFGE) typing demonstrated the imitation crab meat and clinical strains to be indistinguishable. Challenge studies performed with a pool of L. monocytogenes strains showed that imitation crab meat, but not olives, supported growth of the organism. In this study we have shown for the first time the potential involvement of imitation crab meat in a small outbreak of listeriosis. In terms of disease prevention, temperature control is critical to prevent or reduce the growth of this foodborne pathogen. In addition, with refrigerated products having a long (> 30 d) shelf life, additional safety factors must be used to prevent the growth of foodborne pathogens such as L. monocytogenes. [source]

Automutanolysin disrupts clinical isolates of cariogenic streptococci in biofilms and planktonic cells

MOLECULAR ORAL MICROBIOLOGY, Issue 6 2009
P. Thanyasrisung
Introduction:, Dental caries remains one of the most common chronic infectious diseases throughout the world. The formation of dental plaque is one of the caries risk factors. As a consequence, the removal of plaque may reduce the incidence of caries development. We identified an autolysin produced by Streptococcus mutans named auto-mutanolysin (Aml). Aml selectively lyses S. mutans and Streptococcus sobrinus. The specificity towards these cariogenic bacteria suggests that Aml may be used to prevent dental caries. Here, with the aim towards therapeutic application, we investigated the lytic activity of Aml against clinical isolates of S. mutans and S. sobrinus using planktonic cells and biofilms. Methods:, Planktonic cell suspensions and biofilms of clinically isolated streptococci were treated with Aml in the absence or the presence of Triton X-100. The lytic activity of Aml was monitored as the change in turbidity. The disruption of biofilms was evaluated by detecting the released DNA by polymerase chain reaction and observing the alteration of optical density of treated biofilms. Results:, Triton X-100 enhances the lytic ability of Aml. Using planktonic cells, Aml had various lysis levels against clinical strains. Repeated Aml treatment showed disruption of the biofilm using the representative clinical strains. Conclusion:, Our study demonstrates that Aml has an ability to lyse planktonic and biofilm cells of clinically isolated mutans streptococci in the presence of Triton X-100. These results suggest the possibility of using Aml as an alternative or additional approach for caries prevention. [source]

Contribution of cell surface protein antigen c of Streptococcus mutans to platelet aggregation

MOLECULAR ORAL MICROBIOLOGY, Issue 5 2009
M. Matsumoto-Nakano
Introduction:,Streptococcus mutans is considered to be one of the pathogens that cause infective endocarditis. The purpose of the present study was to examine the properties of S. mutans with regard to platelet aggregation by focusing on its high molecular protein antigen c (PAc). Methods:, The platelet aggregation properties of six clinical strains and one isogenic mutant strain of S. mutans were analysed using an aggregometer and confocal microscopy, as well as with an inhibition assay of platelet aggregation using anti-PAc serum. Results:,S. mutans strains with PAc expression induced platelet aggregation, while a PAc-deficient mutant and two clinical isolates with no PAc expression did not. When platelets were pretreated with higher amounts of anti-PAc serum, the platelet aggregation rate was reduced in a dose-dependent manner, indicating that PAc binds directly to platelets. Conclusion:,S. mutans PAc is involved in human platelet aggregation and may be one of the virulence factors in the pathogenesis of infective endocarditis. [source]

Zeocin resistance as a dominant selective marker for transformation and targeted gene deletions in Candida glabrata

Geographically dependent distribution of gyrA gene mutations at codons 83 and 87 in Salmonella Hadar, and a novel codon 81 Gly to His mutation in Salmonella Enteritidis

APMIS, Issue 3 2004
B. A. LINDSTEDT
In all, 90 nalidixic acid-resistant clinical strains of Salmonella Hadar and Salmonella Enteritidis isolated in Norway but of predominantly foreign origin were subjected to sequencing of the gyrA, gyrB, parC and parE genes. All the isolates contained at least one mutation in gyrA codon 83 or codon 87. A highly significant correlation between mutations in gyrA codon 83 and strains originating from Southeast Asia was found in S. Hadar but not in S. Enteritidis. A novel gyrA codon 81 Gly to His mutation was discovered in one S. Enteritidis isolate. One amino-acid (aa) changing mutation was found outside the quinolone resistance-determining region (QRDR) of S. Hadar parC at codon 57, which has previously only been observed once in Salmonellae. [source]

Proteome mapping of overexpressed membrane-enriched and cytosolic proteins in sodium antimony gluconate (SAG) resistant clinical isolate of Leishmania donovani

BRITISH JOURNAL OF CLINICAL PHARMACOLOGY, Issue 4 2010
Awanish Kumar
WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT Over 60% of patients with visceral leishmaniasis (VL) in India and Sudan have become unresponsive to treatment with pentavalent antimonials, the first line of drugs for over 60 years. The drug resistance mechanism, studied so far in in vitro selected laboratory strains, has been attributed to various biochemical parameters. The resistance to Sb (V) in Leishmania field isolates is still unexplored. WHAT THIS STUDY ADDS In order to elucidate for the first time the mechanism of drug resistance in field isolates, this study was done in those clinically relevant field isolates which were either responsive or non responsive to SAG. A comparison of proteome profiles of membrane-enriched as well as cytosolic protein fractions of these isolates has pinpointed the multiple overexpressed proteins in resistant isolates. This study has indicated their possible essential role in antimony resistance of the parasite and provides a vast field to be exploited to find much needed novel treatment strategies against VL. AIMS This study aimed to identify differentially overexpressed membrane-enriched as well as cytosolic proteins in SAG sensitive and resistant clinical strains of L. donovani isolated from VL patients which are involved in the drug resistance mechanism. METHODS The proteins in the membrane-enriched as well as cytosolic fractions of drug-sensitive as well as drug-resistant clinical isolates were separated using two-dimensional gel electrophoresis and overexpressed identified protein spots of interest were excised and analysed using MALDI-TOF/TOF. RESULTS Six out of 12 overexpressed proteins were identified in the membrane-enriched fraction of the SAG resistant strain of L. donovani whereas 14 out of 18 spots were identified in the cytosolic fraction as compared with the SAG sensitive strain. The major proteins in the membrane-enriched fraction were ABC transporter, HSP-83, GPI protein transamidase, cysteine,leucine rich protein and 60S ribosomal protein L23a whereas in the cytosolic fraction proliferative cell nuclear antigen (PCNA), proteasome alpha 5 subunit, carboxypeptidase, HSP-70, enolase, fructose-1,6-bisphosphate aldolase, tubulin-beta chain have been identified. Most of these proteins have been reported as potential drug targets, except 60S ribosomal protein L23a and PCNA which have not been reported to date for their possible involvement in drug resistance against VL. CONCLUSION This study for the first time provided a cumulative proteomic analysis of proteins overexpressed in drug resistant clinical isolates of L. donovani indicating their possible role in antimony resistance of the parasite. Identified proteins provide a vast field to be exploited for novel treatment strategies against VL such as cloning and overexpression of these targets to produce recombinant therapeutic/prophylactic proteins. [source]