| 171. |
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| 172. |
- Lindstrom, A., et al.
(författare)
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Pyrosequencing for detection of lamivudine-resistant hepatitis B virus
- 2004
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 42:10, s. 4788-4795
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Tidskriftsartikel (refereegranskat)abstract
- Chronic hepatitis B virus (HBV) infection can cause severe liver disease, including cirrhosis and hepatocellular carcinoma. Lamivudine is a relatively recent alternative to alpha interferon for the treatment of HBV infection, but unfortunately, resistance to lamivudine commonly develops during monotherapy. Lamivudine-resistant HBV mutants display specific mutations in the YMDD (tyrosine, methionine, aspartate, aspartate) motif of the viral polymerase (reverse transcriptase [rt]), which is the catalytic site of the enzyme, i.e., methionine 204 to isoleucine (rtM204I) or valine (rtM204V). The latter mutation is often accompanied by a compensatory leucine-to-methionine change at codon 180 (rtL180M). In the present study, a novel sequencing method, pyrosequencing, was applied to the detection of lamivudine resistance mutations and was compared with direct Sanger sequencing. The new pyrosequencing method had advantages in terms of throughput. Experiments with mixtures of wild-type and resistant viruses indicated that pyrosequencing can detect minor sequence variants in heterogeneous virus populations. The new pyrosequencing method was evaluated with a small number of patient samples, and the results showed that the method could be a useful tool for the detection of lamivudine resistance in the clinical setting.
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| 173. |
- Liu, Wen-Chun, et al.
(författare)
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Simultaneous quantification and genotyping of hepatitis B virus for genotypes A to G by real-time PCR and two-step melting curve analysis.
- 2006
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Ingår i: Journal of clinical microbiology. - 0095-1137. ; 44:12, s. 4491-7
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Tidskriftsartikel (refereegranskat)abstract
- Both the viral titer and the genotype significantly determine clinical outcomes and responses to antiviral treatment in chronic hepatitis B virus (HBV) infection. A method was developed for large-scale A-to-G genotyping with simultaneous viral quantification. The assay was run on a LightCycler instrument using hybridization probes. The genotype was determined from the melting points of the probes in a two-step manner. Set 1 amplicons differentiated genotypes B, E, and F from A, C, D, and G and simultaneously quantified viremia by real-time PCR. Melting curve analysis using the set 2-1 amplicon or the set 2-2 amplicon reaction mixture was then used to differentiate these genotype groups into single genotypes. HBV DNA quantification was consistent with that of the Amplicor assay and linear in a range from 10(2) to 10(13) copies/ml. By comparison with the restriction fragment length polymorphism method, 92.3% of 441 samples were accurately genotyped by the current assay. The method should be useful for genotyping and quantification of HBV DNA in areas where all genotypes exist.
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| 174. |
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| 175. |
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| 176. |
- Luan, Shi-Lu, et al.
(författare)
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Multilocus sequence typing of Swedish invasive group B streptococcus isolates indicates a neonatally associated genetic lineage and capsule switching.
- 2005
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Ingår i: Journal of clinical microbiology. - 0095-1137 .- 1098-660X. ; 43:8, s. 3727-33
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcus agalactiae, also designated group B streptococcus (GBS), is an important pathogen in neonates, pregnant women, and nonpregnant adults with predisposing conditions. We used multilocus sequence typing (MLST) to characterize 158 GBS isolates that were associated with neonatal and adult invasive disease and that were collected in northern and western Sweden from 1988 to 1997. Five major genetic lineages (sequence type [ST] 19, ST-17, ST-1, ST-23, and ST-9 complexes) were identified among the isolates, including serotype Ia, Ib, and II to V isolates, indicating a highly clonal population structure among invasive GBS isolates. A number of STs were found to contain isolates of different serotypes, which indicates that capsule switching occurred rather frequently. Two distantly related genetic lineages were identified among isolates of serotype III, namely, clonal complex 19 (CC19), and CC17. CC19 was equally common among isolates from adult and neonatal disease (accounting for 10.3% of GBS isolates from adult disease and 18.7% from neonatal disease), whereas CC17 significantly appeared to be associated with neonatal invasive disease (isolated from 21.9% of neonatal isolates but only 2.6% of adult isolates). The distribution of the mobile elements GBSi1 and IS1548 reveals that they can act as genetic markers for lineages CC17 and CC19, respectively.
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| 177. |
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| 178. |
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| 179. |
- Lund, Bodil, et al.
(författare)
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Frequent transmission of enterococcal strains between mechanically ventilated patients treated at an intensive care unit
- 2002
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Ingår i: Journal of Clinical Microbiology. - 0095-1137 .- 1098-660X. ; 40:6, s. 2084-2088
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Tidskriftsartikel (refereegranskat)abstract
- The objectives of this investigation were to study the respiratory tract colonization and transmission of enterococci between 20 patients treated with mechanical ventilation at an intensive care unit (ICU), to compare genotyping with phenotyping, and to determine the antibiotic susceptibilities of the isolated enterococci. Samples were collected from the oropharynx, stomach, subglottic space, and trachea within 24 It of intubation, every third day until day 18, and thereafter every fifth day until day 33. Enterococcal isolates (n = 170) were analyzed by pulsed-field gel electrophoresis and with the PhenePlate (PhP) system. The antimicrobial susceptibilities to five agents were determined. Seventeen of the 20 subjects were colonized with enterococci in the respiratory tract; 12 were colonized in the lower respiratory tract. Genotype analyses suggested that 13 patients were involved in a transmission event, including all patients intubated more than 12 days. In conclusion, colonization of resistant enterococci in the respiratory tract of intubated patients treated at an ICU was common. Transmission of enterococci between patients occurred frequently. Prolonged intubation period seems to be a risk factor for enterococcal cross-transmission.
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| 180. |
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