| 31. |
- Herrera, Phabiola M, et al.
(författare)
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DNA-level diversity and relatedness of Helicobacter pylori strains in shantytown families in Peru and transmission in a developing-country setting.
- 2008
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 46:12, s. 3912-3918
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Tidskriftsartikel (refereegranskat)abstract
- The efficiency of transmission of a pathogen within families compared with that between unrelated persons can affect both the strategies needed to control or eradicate infection and how the pathogen evolves. In industrialized countries, most cases of transmission of the gastric pathogen Helicobacter pylori seems to be from mother to child. An alternative model, potentially applicable among the very poor in developing countries, where infection is more common and the sanitary infrastructure is often deficient, invokes frequent transmission among unrelated persons, often via environmental sources. In the present study, we compared the genotypes of H. pylori from members of shantytown households in Peru to better understand the transmission of H. pylori in developing-country settings. H. pylori cultures and/or DNAs were obtained with informed consent by the string test (a minimally invasive alternative to endoscopy) from at least one child and one parent from each of 62 families. The random amplified polymorphic DNA fingerprints of 57 of 81 (70%) child-mother strain pairs did not match, nor did the diagnostic gene sequences (>1% DNA sequence difference), independent of the child's age (range, 1 to 39 years). Most strains from siblings or other paired family members were also unrelated. These results suggest that H. pylori infections are often community acquired in the society studied. Transmission between unrelated persons should facilitate the formation of novel recombinant genotypes by interstrain DNA transfer and selection for genotypes that are well suited for individual hosts. It also implies that the effective prevention of H. pylori infection and associated gastroduodenal disease will require anti-H. pylori measures to be applied communitywide.
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| 32. |
- Hjorth, SV, et al.
(författare)
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Sequence-based typing of Mycoplasma genitalium reveals sexual transmission
- 2006
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 44:6, s. 2078-2083
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Tidskriftsartikel (refereegranskat)abstract
- Mycoplasma genitalium causes male nonchlamydial, nongonococcal urethritis and is associated with cervicitis and pelvic inflammatory disease in women. Epidemiological studies indicate that M. genitalium is sexually transmitted, and the aim of the present study was to further substantiate this by means of a DNA typing system. A typing assay based on a diagnostic mgpB gene PCR was developed, evaluated, and applied directly to urogenital specimens. The assay had a low limit of detection and hence a high typeability. Sequences of isolates from 52 unrelated patients were divided into 29 different sequence types, giving a discriminatory index of 0.95. Two to six M. genitalium-positive specimens were collected from each of 44 patients over a median interval of 56 days (range, 11 to 1,395). Forty had the same sequence type in consecutive specimens. Specimens collected from two men were repeatedly positive at intervals of 472 and 1,395 days, respectively, but the sequence types had changed. A new strain was introduced in one sexual dyad, and the sequence types changed subsequently. Seventy-nine M. genitalium-positive specimens from 19 couples were investigated, and all partners initially had concordant sequence types, but one couple had discordant types at one time point before a newly introduced strain took over. The present typing system is simple and reproducible and has an excellent discriminatory capacity which might prove useful in studies of sexual networks and for evaluation of treatment failures. In the laboratory, this system may document the uniqueness of newly isolated M. genitalium strains.
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| 33. |
- Hogberg, Liselotte, et al.
(författare)
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Age- and serogroup-related differences in observed durations of nasopharyngeal carriage of penicillin-resistant pneumococci
- 2007
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 45:3, s. 948-952
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Tidskriftsartikel (refereegranskat)abstract
- Using data from an ongoing Swedish intervention project, the observed durations of nasopharyngeal carriage of penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) (MIC of penicillin G of >= 0.5 mu g/ml) stratified by both pneumococcal serogroup and age of the carrier were compared. The means and 95% confidence intervals (CIs) were estimated by fitting a gamma distribution to the observed duration of carriage for each age and serogroup stratum. The mean observed duration of carriage for all cases was 37 days (95% CI, 35 to 38 days). Children below the age of 5 years carried PNSP for significantly longer periods (43 days; 95% CI, 41 to 45 days) compared with older individuals (25 days; 95% CI, 24 to 27 days). There were also differences within the group of cases below the age of 5 years, as the duration of carriage became significantly shorter for each increasing age step: < 1, 1 to 2, and 3 to 4 years. In addition, patients < 5 years of age carried serogroups 9 and 14 for significantly shorter periods than groups 6 and 23. Serogroup 9 was also carried for significantly shorter periods than group 19. For patients aged 5 years or older, no significant difference in carriage duration for different ages or serogroups could be noted. As young children have the longest duration of PNSP carriage, interventions aiming to reduce the prevalence in this group are of great importance. The results highlight the importance of taking both serogroup and age of the carriers into account when studying the dynamics of pneumococcal transmission in young children.
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| 34. |
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| 35. |
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| 36. |
- Innings, Åsa, et al.
(författare)
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Multiplex real-time PCR targeting the RNase P RNA gene for detection and identification of Candida species in blood
- 2007
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 45:3, s. 874-880
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Tidskriftsartikel (refereegranskat)abstract
- We have developed a single-tube multiplex real-time PCR method for the detection of the eight most common Candida species causing septicemia: Candida albicans, C. dubliniensis, C. famata, C. glabrata, C. guilliermondii, C. krusei, C. parapsilosis, and C. tropicalis. The method developed targets the RNase P RNA gene RPR1. Sequences of this geiie were determined for seven of the Candida species and showed surprisiRgly large sequence variation. C. glabrata was found to have a gene that was five times longer gene than those of the other species, and the nucleotide sequence similarity between C. krusei and C. albicans was as low as 55%. The multiplex PCR contained three probes that enabled the specific detection of C. albicans, C. glabrata, and C. krusei and a fourth probe that allowed the general detection of the remaining species. The method was able to detect 1 to 10 genome copies when the detection limit was tested repeatedly for the four species C. albicans, C. glabrata, C. krusei, and C. guilliermondii. No significant difference in the detection limit was seen when the multiplex format was compared with single-species PCR, i.e., two primers and one probe. The method detected eight clinically relevant Candida species and did not react with other tested non-Candida species or human DNA. The assay was applied to 20 blood samples from nine patients and showed a sensitivity similar to that of culture.
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| 37. |
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| 38. |
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| 39. |
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| 40. |
- Johansson, Anders, 1966-, et al.
(författare)
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Multiple-locus variable-number tandem repeat analysis for typing of Staphylococcus epidermidis.
- 2006
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 44:1, s. 260-5
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Tidskriftsartikel (refereegranskat)abstract
- We applied a high-resolution PCR-based typing method, multiple-locus variable-number tandem repeat analysis (MLVA), for discrimination of 30 multidrug-resistant clinical isolates of Staphylococcus epidermidis. The results of MLVA were congruent with results obtained by pulsed-field gel electrophoresis (PFGE). MLVA generated discrete character data, and its discriminatory capacity was comparable to that of PFGE.
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