Biomedical subjects

P Kriz

Publications and source records attributed to P Kriz.

At least 19 recordsLinked to original sources

PubMed2006

Dynamics of PCR-based diagnosis in patients with invasive meningococcal disease.

Invasive meningococcal disease continues to be a life-threatening condition and rapid diagnosis is important for the administration of appropriate treatment. This study focused on the use of PCR for the diagnosis of meningococcal aetiology and the dynamics of PCR-based diagnosis over time in various biological samples. Sixty cerebrospinal fluid (CSF) and 144 serum samples collected during the first week of hospitalisation from 37 patients with laboratory-confirmed invasive meningococcal disease were investigated. Overall, 91.9% of CSF samples and 45.9% of serum samples were PCR-positive, while culture of CSF and blood was positive for only 35% and 39% samples, respectively. Positive PCR results were obtained until day 7 with CSF and until day 5 with serum. It is therefore recommended that samples for molecular diagnosis should be collected early in the course of suspected invasive meningococcal disease.

Adolescent↗

PubMed2004

The influence of mutation, recombination, population history, and selection on patterns of genetic diversity in Neisseria meningitidis.

Patterns of genetic diversity within populations of human pathogens, shaped by the ecology of host-microbe interactions, contain important information about the epidemiological history of infectious disease. Exploiting this information, however, requires a systematic approach that distinguishes the genetic signal generated by epidemiological processes from the effects of other forces, such as recombination, mutation, and population history. Here, a variety of quantitative techniques were employed to investigate multilocus sequence information from isolate collections of Neisseria meningitidis, a major cause of meningitis and septicemia world wide. This allowed quantitative evaluation of alternative explanations for the observed population structure. A coalescent-based approach was employed to estimate the rate of mutation, the rate of recombination, and the size distribution of recombination fragments from samples from disease-associated and carried meningococci obtained in the Czech Republic in 1993 and a global collection of disease-associated isolates collected globally from 1937 to 1996. The parameter estimates were used to reject a model in which genetic structure arose by chance in small populations, and analysis of molecular variation showed that geographically restricted gene flow was unlikely to be the cause of the genetic structure. The genetic differentiation between disease and carriage isolate collections indicated that, whereas certain genotypes were overrepresented among the disease-isolate collections (the "hyperinvasive" lineages), disease-associated and carried meningococci exhibited remarkably little differentiation at the level of individual nucleotide polymorphisms. In combination, these results indicated the repeated action of natural selection on meningococcal populations, possibly arising from the coevolutionary dynamic of host-pathogen interactions.

Adolescent↗

PubMed2004

Comparison of Streptococcus pneumoniae serotypes causing acute otitis media & invasive disease in young children in the Czech Republic.

BACKGROUND & OBJECTIVES: The availability of a type-specific pneumococcal vaccine for children is a worldwide problem. It is necessary to study the serotypes prevalent in a country before introducing a type-specific vaccine. The objective of the present study was to analyse the prevalence of Streptococcus pneumoniae serotypes in children suffering from acute otitis media or invasive pneumococcal disease and to compare a coverage of serotypes by individual pneumococcal vaccines. METHODS: Children suffering from acute otitis media and invasive pneumococcal disease were analysed in the Czech Republic from October 1999 to November 2000. Serotyping was performed by the quellung technique using antisera from Statens Serum Institute (Denmark). RESULTS: The most frequent serotypes in patients with acute otitis media were 3, 19F, 23F, 14, 9V, 1, 6B, 11A and 28F. Vaccine coverage for the identified serotypes in acute otitis media patients was 52.1 per cent for the 7-valent vaccine, 57.8 per cent for the 9-valent vaccine and 75.7 per cent for the 11-valent form of the vaccine. In 108 patients with invasive pneumococcal disease, the most frequent serotypes were 6B, 9V, 14, 19F, 3 and 23F. Vaccine coverage for the identified serotypes in patients with invasive pneumococcal disease was 62 per cent for the 7-valent vaccine, 66.4 per cent for the 9-valent vaccine and 77.5 per cent for the 11-valent form of the vaccine. INTERPRETATION & CONCLUSION: Vaccine coverage for the identified serotypes for the 11-valent pneumococcal vaccine was better than the other two vaccines.

Acute Disease↗

PubMed2004

Surveillance of invasive meningococcal disease in the Czech Republic.

Routine notification of invasive meningococcal disease has a long tradition in the Czech Republic: mortality data are available from 1921 and morbidity data from 1943. The collection of Neisseria meningitidis strains kept in the NRL for Meningococcal Infections in Prague dates from 1970 onwards, and represents more than 3500 strains isolated from invasive disease and their contacts, from healthy carriers and from respiratory infection. Analysis of these strains showed that the Czech meningococcal population is different from that seen in western Europe. In 1993, the incidence serogroup C meningococcal disease increased and was associated with the emergence of the hypervirulent complex Neisseria meningitidis C, ST-11, ET-15/37, and caused an increase in the incidence of invasive meningococcal disease which peaked in 1995 (2.2/100,000). A vaccination strategy targeting the part of the population at highest risk of invasive meningococcal disease was adopted in the country.

Czech Republic↗

PubMed2002

Multilocus sequence typing of Neisseria meningitidis directly from cerebrospinal fluid.

MLST typing of Neisseria meningitidis directly from clinical material was introduced in the National Reference Laboratory for Meningococcal Infections in Prague. Four cerebrospinal fluid samples were obtained from patients with suspected meningococcal invasive disease. In all samples, all classical laboratory methods gave negative results and the only positive method was PCR, which revealed Neisseria meningitidis group C (two specimens) and group B (two specimens), respectively. MLST performed directly from cerebrospinal fluid revealed that the strains causing the two group C infections were of sequence type (ST) 11, while the two group B infections were characterized as ST-32 and ST-33 respectively. Multi-locus sequence typing of meningococci directly from clinical material offers the opportunity to improve further the surveillance of meningococcal disease and has now been introduced into the routine portfolio of tests employed at the national reference laboratory of the Czech Republic.

Adolescent↗

PubMed2001

Polymorphism of Neisseria meningitidis penA gene associated with reduced susceptibility to penicillin.

We studied polymorphism of penA (which encodes penicillin-binding protein 2) in 13 strains of Neisseria meningitidis susceptible to penicillin (pen(S)) and 12 strains with reduced susceptibility to penicillin (pen(I)). These strains differed in geographical origin. Serological and genetic typing showed that they were highly diverse and belonged to several genetic lineages. Restriction analysis and DNA sequencing of penA showed that all pen(S) strains had the same penA allele regardless of genetic group, whereas pen(I) strains harboured various penA alleles. Transformation with amplicons of penA and genomic DNA from several pen(I) strains conferred the pen(I) phenotype on a pen(S) strain. Thus, reduction in susceptibility to penicillin is directly related to changes in penA and analysis of penA polymorphisms could be used as a reliable tool for characterizing meningococcal strains in terms of their susceptibility to penicillin.

Alleles↗

PubMed2001

Phenotypic and genotypic approaches to characterization of isolates of Neisseria meningitidis from patients and their close family contacts.

Characterization of isolates of Neisseria meningitidis obtained from patients with meningococcal disease or from pharyngeal swabs of asymptomatic carriers can be achieved by several approaches which provide different levels of discrimination. A total of 45 gram negative, oxidase-positive diplococcus strains isolated from 15 individuals with meningococcal disease and 30 of their family contacts were examined by three approaches: serological typing, multilocus enzyme electrophoresis (MLEE), and multilocus sequence typing (MLST). For 10 of the 15 patient and contact groups, all of the isolates were confirmed as meningococci, and the bacteria obtained from the patients and contacts, including their mother or principal caregiver in the case of children, were indistinguishable by all three methods. In the remaining five groups the isolates from the patients were distinct from those recovered from the contacts, and in three examples, in two separate groups, the contacts were shown by MLST to be carrying strains of Neisseria lactamica. The data obtained from the three techniques were consistent, although complete serological typing was possible for only a minority of isolates. Both MLEE and MLST established the genetic relationships of the isolates and identified members of known hypervirulent lineages, but MLST was faster than MLEE and had the additional advantages that it could be performed on noninfective material distributed by mail and that the results from different laboratories could be compared via the internet (http://mlst.zoo.ox.ac.uk).

Adolescent↗

PubMed2000

Genetic and antigenic characteristics of Neisseria meningitidis strains isolated in the Czech Republic in 1997-1998.

Strains of Neisseria meningitidis isolated from patients and asymptomatic individuals who had been in contact with patients were investigated using four typing methods with the aim of identifying any heterogeneity and/or homogeneity among the strains. In 1993, a dramatic change in the incidence and severity of invasive meningococcal disease in the Czech Republic occurred as a consequence of the appearance of a Neisseria meningitidis strain of phenotype C:2a:P1.5,2 and electrophoretic type ET-15, belonging to the ET-37 complex, which had not previously been identified in this country. Presented here are the results of a study of the relationships between 58 Neisseria meningitidis isolates collected between January 1997 and June 1998. Forty-nine isolates originating from patients with invasive meningococcal disease and nine from healthy contacts were analyzed using the following four methods: whole-cell enzyme immunoassay, multilocus enzyme electrophoresis, pulsed-field gel electrophoresis, and randomly amplified polymorphic DNA analysis. A high prevalence of phenotype C:2a:P1.5,2 electrophoretic type ET-15 was confirmed among the patients' strains. Nevertheless, during the study period, they became heterogeneous. Strains isolated from healthy contacts showed greater heterogeneity in serological phenotypes and electrophoretic types from the beginning of the study, and electrophoretic type ET-15 strains were less frequent. Within the electrophoretic type ET-15 clone, strains showing the identical serological phenotype (with the exception of one isolate) were indistinguishable using randomly amplified polymorphic DNA analysis, while pulsed-field gel electrophoresis revealed heterogeneity with 12 pulsed-field gel electrophoretic types identified. The strains from the same cluster displaying the same serological phenotype were indistinguishable with any of the methods used.

Cluster Analysis↗

PubMed2000

Characteristics of the major etiologic agents of bacterial meningitis isolated in Poland in 1997-1998.

Bacterial meningitis remains a major cause of morbidity and mortality worldwide, especially in children. In this paper, we present the results of the first two years (1997-98) of activity of the National Reference Centre for Bacterial Meningitis (NRCBM) on the etiologic agents of bacterial meningitis in Poland. Of the 220 isolates sent to the NRCBM, the most frequently identified was Neisseria meningitidis (n = 90, 40.9%), followed by Haemophilus influenzae (n = 58, 26.4%), and Streptoccus pneumoniae (n = 46, 20.9%). Of the meningococcal isolates, 88.9% belonged to serogroup B and 10.0% to serogroup C, and the most prevalent serotype was 22 (43.3%). Most meningococci were highly sensitive to penicillin; however, 10% of them had decreased susceptibility to penicillin. More than 90% of H. influenzae belonged to serotype b, and all were susceptible to third generation cephalosporins and chloramphenicol. A broad distribution of serotypes was found among pneumococcal isolates, of which the most common were serotypes 3 and 8. Penicillin nonsusceptible isolates constituted 13% of all pneumococcal isolates. Three of the resistant pnemococci belonged to serotype 23F. Data presented in this paper demonstrate the current epidemiological situation of bacterial meningitis in Poland.

Adolescent↗

PubMed2000

Carried meningococci in the Czech Republic: a diverse recombining population.

Population and evolutionary analyses of pathogenic bacteria are frequently hindered by sampling strategies that concentrate on isolates from patients with invasive disease. This is especially so for the gram-negative diplococcus Neisseria meningitidis, a cause of septicemia and meningitis worldwide. Meningococcal isolate collections almost exclusively comprise organisms originating from patients with invasive meningococcal disease, although this bacterium is a commensal inhabitant of the human nasopharynx and very rarely causes pathological effects. In the present study, molecular biology-based techniques were used to establish the genetic relationships of 156 meningococci isolated from healthy young adults in the Czech Republic during 1993. None of the individuals sampled had known links to patients with invasive disease. Multilocus sequence typing (MLST) showed that the bacterial population was highly diverse, comprising 71 different sequence types (STs) which were assigned to 34 distinct complexes or lineages. Three previously identified hyperinvasive lineages were present: 26 isolates (17%) belonged to the ST-41 complex (lineage 3); 4 (2.6%) belonged to the ST-11 (electrophoretic type [ET-37]) complex, and 1 (0.6%) belonged to the ST-32 (ET-5) complex. The data were consistent with the view that most nucleotide sequence diversity resulted from the reassortment of alleles by horizontal genetic exchange.

Adolescent↗

PubMed2000

Parental smoking, socioeconomic factors, and risk of invasive meningococcal disease in children: a population based case-control study.

AIMS: To investigate the effects of parental smoking, socioeconomic characteristics, and indoor environment on the risk of invasive meningococcal disease in children. METHODS: Population based case-control study. A total of 68 incident cases of invasive meningococcal disease in children less than 15 years old were compared with 135 controls selected from the same school and matched for year of birth, sex, and place of residence. Information on exposures was obtained in interviews with parents. RESULTS: Invasive meningococcal disease was strongly associated with parental smoking; rate ratios adjusted for socioeconomic factors were 3.5 (95% confidence interval 1.4-8.7) for smoking of mother, 3.2 (1.5-6.9) for smoking of father, and 2.7 (1.3-5.4) for every 20 cigarettes smoked at home on an average day. The risk of the disease was strongly inversely related to maternal education and, less strongly, to ownership of a car and of a weekend house, father's education, crowding, and the number of siblings, but these associations were reduced or eliminated in multivariate models. The type of heating and cooking (used as proxies for indoor air pollution) were not associated with the disease. CONCLUSION: The risk of invasive meningococcal disease in children is strongly influenced by parental smoking and unfavourable socioeconomic circumstances.

Adolescent↗

PubMed2000

Interactions of invasive and noninvasive strains of Neisseria meningitidis with monkey epithelial cells, mouse monocytes and human macrophages.

Adherence and phagocytosis of invasive and noninvasive Neisseria meningitidis strains was investigated using light, fluorescence and electron microscopy. Invasive strains were isolated from the cerebrospinal fluid and/or blood of the patients with invasive meningococcal disease and noninvasive strains from the nasopharynx and/or larynx of healthy carriers. Adherence/endocytosis was studied on monkey kidney cells (the LLC-MK2 cell line) and phagocytosis on mouse monocytes and human macrophages (the P388D1 and U-937 cell lines, respectively). Although invasive and noninvasive meningococci isolated in the same cluster showed identical genotype and phenotype markers, they were found to interact differently with epithelial cells as well as with monocytes/macrophages. Invasive isolates displayed higher adherence to the surface of LLC-MK2 cells compared to noninvasive ones. Phagocytosis by P388D1 cells of noninvasive strains was effective and the bacteria were damaged by cytolysis. In contrast, invasive bacteria frequently persisted in "coiling" vacuoles and in effect could destroy the host cell. This is the first demonstration of coiling phagocytosis induced by meningococci. Efficiency of phagocytosis by U-937 cells was significantly higher for the noninvasive than invasive strains. Different behaviour of invasive and noninvasive strains of N. meningitidis observed during 4 hours of interactions with epithelial cells and monocytes/macrophages reflects well the higher pathogenic potential of invasive bacteria.

Animals↗

PubMed1999

Microevolution through DNA exchange among strains of Neisseria meningitidis isolated during an outbreak in the Czech Republic.

Neisseria meningitidis is a highly variable bacterium. Indeed, N. meningitidis is naturally competent for transformation, and horizontal DNA exchange between strains may lead to mosaic genetic loci in N. meningitidis. We studied such an exchange in nature during an epidemic provoked by N. meningitidis. This epidemic started in the Czech Republic in 1993 and the original epidemic clone was shown to have the antigenic formula (serogroup:serotype:serosubtype) C:2a:P1.2,5. We analysed 145 meningococcal strains isolated in the Czech Republic between 1993 and 1997 using serological and genetic typing methods (multilocus enzyme electrophoresis and polymorphism of pilA and pilD genes). This analysis showed that genetic exchange between epidemic and endemic strains had occurred. Exchanges involved mostly surface-exposed structures such as the capsule, giving rise to new meningococcal variants. The expansion of these variants should be kept under close surveillance.

Alleles↗

PubMed1999

Antimeningococcal herd immunity in the Czech Republic--influence of an emerging clone, Neisseria meningitidis ET-15/37.

For many years, invasive meningococcal disease in the Czech Republic occurred sporadically and was caused mainly by meningococci of serogroup B. In 1993, when a new clone (ET-15/37) emerged, the only phenotype found was C:2a:P1.2,5. In 1995, an antigenic variation of the ET-15/37 clone, B:2a:P1.2,5, occurred. The results of immunological surveys conducted in 1989 and 1996 were compared. A significantly higher proportion of 1996 sera than those collected in 1989 showed bactericidal antibodies against N. meningitidis B:2a:P1.2,5 (19.7 vs. 5.1%) and N. meningitidis C:2a:P1.2,5 (15.9 vs. 7.4%), consistent with increased herd immunity due to the spread of the new clone in the Czech Republic. There were differences in the age distribution of the positive sera.

Adolescent↗

PubMed1999

Recent emergence of serogroup C meningococcal disease in Greece.

The number of cases of meningococcal disease reported to the Meningitis Reference Laboratory in Athens rose dramatically in 1996-1997. The aims were (1) to determine if the increase was due to introduction of new strains, (2) to assess the geographic and age distribution of the cases, (3) to compare antibiotic sensitivity patterns of the current isolates with strains from the early 1990s. In 1993-1994, 15/19 (74%) of the cases for which information on age was available were in children < or = 5 years; in 1995-1997, 80/179 (45%) of cases were in children < or = 5 years and 99 (55%) in the older age range (P < 0.02). From 593 cases in 1993 1997, 214 (36%) isolates were available for characterisation. Serogroup B was predominant in the early 1990s, but by 1997, serogroup C accounted for 46/72 (64%) of isolates and serogroup B for 25/72 (35%). Serogroup B was predominant in children < or = 5 years (44/78, 56%) but only 19/99 (18%) of older children and adults (P=0.0000005). Sulfonamide resistance decreased from 10/22 (45%) in 1993-1994 to 27/192 (14%) in 1995-1997 (P<0.01). Multilocus enzyme electrophoresis of 70 strains obtained during this period identified the epidemic ET-15 clone in 24 (34.3)%. The profiles of the Greek ET-15 isolates were identical to C:2a:P1.2(P1.5) strains responsible for the epidemic in the Czech Republic which began in 1993. This genotype was not found in Greek strains isolated prior to 1993. We conclude that the increase in meningococcal disease is due to introduction of the epidemic serogroup C:2a:P1.2(P1.5) strain responsible for disease in the Czech Republic and Canada.

Adolescent↗

PubMed1999

A quit smoking group. Pilot study.

1. While the rate of smoking is extremely high among persons with mental illness, there have been efforts to assist this population to quit. A 10-week smoking cessation program was provided for 10 highly nicotine dependent persons with persistent mental illness. 2. No significant differences were found in psychiatric symptoms or drug side effects prior to and after smoking cessation efforts. Four months later, for the 7 subjects who completed the program, 14% were abstinent, 43% maintained reduced tobacco intake, and 43% had resumed previous smoking patterns. 3. Specific barriers to quitting include a lack of nonsmoking coping skills, long-term identity as a smoker, ready access to tobacco products, nicotine addiction, and limited nonsmoking social support.

Adult↗

PubMed1998

Heterogeneity of the PorB protein in serotype 22 Neisseria meningitidis.

The genetic diversity of porB genes from meningococcal isolates characterized as serotype 22 was investigated by gene sequencing. This procedure identified seven distinct porB sequences, demonstrating variation in the PorB protein recognized by the serotype 22 monoclonal antibody. This is consistent with the genetic heterogeneity of serotype 22 meningococci reported previously.

Amino Acid Sequence↗

PubMed1998

Genetic heterogeneity of strains of Neisseria meningitidis belonging to serotype 22 isolated in the Czech Republic.

Strains of Neisseria meningitidis of serogroup B isolated in the Czech Republic frequently belong to serotype 22. We analyzed the genetic relationships among strains of this serotype by using the multilocus enzyme electrophoresis technique and the polymorphism of the pilA gene. Our results indicate that these strains correspond to a highly heterogeneous population rather than to the expansion of a single clone.

Alleles↗