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A Efstratiou

Publications and source records attributed to A Efstratiou.

At least 55 records · Page 3Linked to original sources
PubMed1999

Diphtheria in the Republic of Georgia: use of molecular typing techniques for characterization of Corynebacterium diphtheriae strains.

Sixty-six Corynebacterium diphtheriae strains (62 of the gravis biotype and 4 of the mitis biotype) isolated during the Georgian diphtheria epidemic of 1993 to 1998 and 13 non-Georgian C. diphtheriae strains (10 Russian and 3 reference isolates) were characterized by (i) biotyping, (ii) toxigenicity testing with the Elek assay and PCR, (iii) the randomly amplified polymorphic DNA (RAPD) technique, and (iv) pulsed-field gel electrophoresis (PFGE). Fifteen selected strains were ribotyped. Six RAPD types and 15 PFGE patterns were identified among all strains examined, and 12 ribotypes were found among the 15 strains that were ribotyped. The Georgian epidemic apparently was caused by one major clonal group of C. diphtheriae (PFGE type A, ribotype R1), which was identical to the predominant epidemic strain(s) isolated during the concurrent diphtheria epidemic in Russia. A dendrogram based on the PFGE patterns revealed profound differences between the minor (nonpredominant) epidemic strains found in Georgia and Russia. The methodologies for RAPD typing, ribotyping, and PFGE typing of C. diphtheriae strains were improved to enable rapid and convenient molecular typing of the strains. The RAPD technique was adequate for biotype differentiation; however, PFGE and ribotyping were better (and equal to each other) at discriminating between epidemiologically related and unrelated isolates.

Bacterial Typing Techniques↗
PubMed1999

High-resolution genotyping of Streptococcus pyogenes serotype M1 isolates by fluorescent amplified-fragment length polymorphism analysis.

We have used fluorescent amplified-fragment length polymorphism (FAFLP) analysis to subtype clinical isolates of Streptococcus pyogenes serotype M1. Established typing methods define most M1 isolates as members of a clone that has a worldwide distribution and that is strongly associated with invasive diseases. FAFLP analysis simultaneously sampled 90 to 120 loci throughout the M1 genome. Its discriminatory power, precision, and reproducibility were compared with those of other molecular typing methods. Irrespective of disease symptomatology or geographic origin, the majority of the clinical M1 isolates shared a single ribotype, pulsed-field gel electrophoresis macrorestriction profile, and emm1 gene sequence. Nonetheless, among these isolates, FAFLP analysis could differentiate 17 distinct profiles, including seven multi-isolate groups. The FAFLP profiles of M1 isolates reproducibly exhibited between 1 and more than 20 amplified fragment differences. The high discriminatory power of genotyping by FAFLP analysis revealed genetic microheterogeneity and differentiated otherwise "identical" M1 isolates as members of a clone complex.

Antigens, Bacterial↗
PubMed1999

Laboratory guidelines for the diagnosis of infections caused by Corynebacterium diphtheriae and C. ulcerans. World Health Organization.

These guidelines represent an application of the World Health Organization European Region's manual for the laboratory diagnosis of diphtheria for laboratories in the United Kingdom (UK), but they could be applied to laboratories overseas. The manual was rewritten in response to the re-emergence of diphtheria in eastern Europe and the emergence of other infections caused by Corynebacterium diphtheriae and C. ulcerans in the UK and overseas. The guidelines summarise our current recommendations and procedures for the microbiological diagnosis of infections caused by toxigenic and non-toxigenic isolates of corynebacteria, with particular reference to C. diphtheriae and C. ulcerans.

Adolescent↗
PubMed1998

Clonal spread of group A streptococcus with the new type of erythromycin resistance. Finnish Study Group for Antimicrobial Resistance.

In 1990, a new type of erythromycin resistance phenotype, designated NR, was found in group A streptococcus (GAS) in Finland. In the present study, the distribution of GAS isolates with this and other erythromycin-resistance phenotypes was surveyed in Finland, and the clonality of the isolates was explored. Of 4179 GAS isolates collected from all over Finland, 695 (17%) were resistant to erythromycin, and 82% of these had the NR phenotype. Of a group of 96 isolates with the NR phenotype from different areas, 91% was T4 serotype, opacity factor-positive. The majority of these isolates were studied further: All were M4 serotype and 88% were of one clonal origin in genetic analyses. Thus, one single clone predominates among erythromycin-resistant GAS in Finland. This clone is of T4M4 serotype and mediates the new type of erythromycin resistance, characterized by the NR phenotype.

Bacterial Typing Techniques↗
PubMed1998

Pneumococci causing invasive disease in Britain 1982-1990.

A total of 5348 isolates of Streptococcus pneumoniae was serotyped and screened for insusceptibility to tetracycline, penicillin, erythromycin and chloramphenicol. Of these, 4238 (79%) were isolated from patients who had pneumonia or meningitis or were bacteraemic. Altogether, 3948 (74%) of the isolates belonged to one or other of the serotypes 1, 3, 4, 6, 8, 9, 14, 19 or 23 with serotypes 6, 14, 18, 19 and 23 being frequent causes of invasive disease in young children. Many isolates of type 1 were isolated from pneumonia and few from meningitis. Some 768 (14%) isolates were insusceptible to one or more antibiotic and 591 of these belonged to serotypes 6, 9, 14, 19 or 23. Representatives of type 14 resistant to erythromycin were prominent from 1986 onwards. There was an increase in the number of multi-resistant pneumococci from 1985. Among these were isolates of type 23 insusceptible to penicillin, chloramphenicol and tetracycline and cultures of type 6 resistant additionally to erythromycin.

Adolescent↗
PubMed1998

Fluorescent amplified-fragment length polymorphism analysis of an outbreak of group A streptococcal invasive disease.

Fluorescent amplified-fragment length polymorphism (FAFLP) analysis was carried out for an outbreak of group A streptococcal (GAS) invasive disease. Streptococcal genomic DNAs were digested with endonucleases EcoRI and MseI, site-specific adaptors were ligated, and PCR amplification was carried out with an EcoRI adaptor-specific primer labelled with fluorescent dye. Amplified fragments of up to 600 bp in size were separated on a polyacrylamide sequencing gel which contained internal size markers in each lane. These data were automatically scanned and analyzed, fragments were precisely sized (+/-1 bp), and electropherograms were generated for each genome with GeneScan 2.1 software. All isolates were compared in this way. Among 27 GAS isolates examined, we found 18 FAFLP profiles, compared with 12 macrorestriction profiles by pulsed-field gel electrophoresis. FAFLP readily distinguished genotypes for two clones of GAS serotype M77 which were responsible for outbreaks of invasive disease in a care-of-the-elderly system. It provided an automated analysis of the whole genome of bacterial isolates. It was reproducible, more discriminatory, and capable of higher throughput than other molecular typing methods. Given agreed conditions, FAFLP would be reproducible between laboratories for rapid characterization of outbreak strains.

Aged↗
PubMed1998

Comparison of phenotypic and genotypic methods for detection of diphtheria toxin among isolates of pathogenic corynebacteria.

We have compared molecular, immunochemical, and cytotoxic assays for the detection of diphtheria toxin from 55 isolates of Corynebacterium diphtheriae and Corynebacterium ulcerans originally isolated in five different countries. The suitabilities and accuracies of these assays for the laboratory diagnosis of diphtheria were compared and evaluated against the "gold standard" in vivo methods. The in vivo and Vero cell cytotoxicity assays were accurate in their abilities to detect diphtheria toxin but were time-consuming; however, the cytotoxicity assay is a suitable in vitro alternative to the in vivo virulence test. There was complete concordance between all the phenotypic methods. Genotypic tests based upon PCR were rapid; however, PCR must be used with caution because some isolates of C. diphtheriae possessed toxin genes but failed to express a biologically active toxin. Therefore, phenotypic confirmation of toxigenicity for the microbiological diagnosis of diphtheria is recommended.

Animals↗
PubMed1997

Serogroups/types and antibiotic resistance of referred isolates of Streptococcus pneumoniae: 1993 to 1995.

Surveillance of prevalent serogroups/types of Streptococcus pneumoniae and their susceptibility to antimicrobial agents is important for understanding the epidemiology of pneumococcal infections and for guiding empirical treatment. Current vaccines for prevention of pneumococcal infection utilise serotype specific antigens, so knowledge of the prevalence of particular serotypes is relevant to vaccine use and development. Five thousand seven hundred and ninety-six isolates of S. pneumoniae from separate patients were serogrouped or serotyped by the Streptococcus and Diphtheria Reference Unit between 1993 and 1995. Antibiotic susceptibility testing was carried out by the Antibiotic Reference Unit on 3821 (65.9%) of these isolates. A total of 40 distinct serogroups/types, together with a small number of non-typable isolates, were noted over the three year period. The same five serogroups/types (6, 9, 14, 19, and 23) occurred most commonly in each year of the study, not only in the total population of isolates studied, but also in isolates obtained from blood or cerebrospinal fluid, and among isolates with antibiotic resistance. Ninety-six per cent of the isolates belonged to serogroups/types included in the currently available 23-valent capsular polysaccharide pneumococcal vaccine; the conjugate petna-, hepta-, and nonavalent vaccines covered 51%, 75%, and 80% of isolates respectively. The nonavalent vaccine offers the most promise as 74% of all blood and cerebrospinal fluid isolates and 90% of antibiotic resistant isolates belonged to serogroups or types included in this formulation.

Anti-Bacterial Agents↗
PubMed1997

Allelic variation in Streptococcus pneumoniae autolysin (N-acetyl muramoyl-L-alanine amidase).

The lytA gene encoding the autolysin of Streptococcus pneumoniae may be a virulence determinant. Single-strand conformational polymorphism analysis demonstrated heterogenicity throughout the gene in clinical isolates and strains from the clonal serotypes 7 and 14. Sequence analysis of part of the choline-binding domain showed that in two isolates four amino acid substitutions occurred.

Alleles↗
PubMed1997

PCR-enzyme-linked immunosorbent assay and sequencing as an alternative to serology for M-antigen typing of Streptococcus pyogenes.

A rapid PCR-enzyme-linked immunosorbent assay for identification of 10 important emm gene types of Streptococcus pyogenes was developed. The emm genotypes of a coded panel of strains of known M serotype were determined, and in 144 of 149 cases (97%) the results were congruous. Strains of types that were not included in the panel of capture probes were emm genotyped by sequencing.

Antigens, Bacterial↗
PubMed1997

A modified Elek test for detection of toxigenic corynebacteria in the diagnostic laboratory.

The detection of toxigenicity among Corynebacterium diphtheriae and Corynebacterium ulcerans strains is the most important test for the microbiological diagnosis of diphtheria. Difficulties with current methods, in particular the Elek test, are well documented. We therefore describe a modified Elek test which provides an accurate result after only 16 h of incubation, in contrast to 48 h for the conventional test.

Bacteriological Techniques↗
PubMed1997

Corynebacterium imitans sp. nov. isolated from patients with suspected diphtheria.

A 5-month-old boy of a Romanian family traveling via Ukraine to Poland developed a respiratory disease that resembled and that was initially diagnosed as pharyngeal diphtheria. The child recovered after treatment with antidiphtheria antitoxin. A coryneform bacterium had been isolated from a nasopharyngeal specimen from the child and was initially identified as an atypical Corynebacterium diphtheriae strain. Seven adults who had contact with either the child or an adult contact person also developed symptoms of pharyngeal diphtheria, were also treated with antitoxin, and recovered uneventfully. Coryneform bacteria similar to that originating from the index patient were also isolated from the throat swabs of three adults. Detailed biochemical and chemotaxonomic investigations revealed that the coryneform bacteria belonged to the genus Corynebacterium and could be differentiated from all other defined species of this genus. Ribotyping and pulsed-field gel electrophoresis demonstrated that all four patients' isolates were of clonal origin. The diphtheria toxin gene and its product were not detected either by PCR assays or by the Elek test, making a possible disease association of the Corynebacterium more unlikely. Comparative 16S rRNA gene sequence analysis revealed that the coryneform bacterium represented a new subline within the genus Corynebacterium, for which the name Corynebacterium imitans sp. nov. is proposed. The type strain is NCTC 13015 (DSM 44264; CCUG 36877).

Corynebacterium↗