| 1. |
- Abdeldaim, Guma, et al.
(författare)
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Usefulness of real-time PCR for lytA, ply, and Spn9802 on plasma samples for the diagnosis of pneumococcal pneumonia
- 2010
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Ingår i: Clinical Microbiology and Infection. - : Elsevier BV. - 1198-743X .- 1469-0691. ; 16:8, s. 1135-1141
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, we evaluated rapid real-time PCR assays for ply, Spn9802, and lytA applied to plasma samples for the detection of Streptococcus pneumoniae in patients with community-acquired pneumonia (CAP). In a prospective study of CAP aetiology, an EDTA plasma sample was collected together with blood culture in 92 adult CAP patients and 91 adult controls. Among the 92 CAP patients, lytA PCR was positive in eight (9%), Spn9802 PCR was positive in 11 (12%) and ply PCR was positive in 19 (21%) cases. Of 91 controls, the ply PCR was positive in eight cases (9%), but no positive cases were noted by Spn9802 or lytA PCRs. Ten CAP patients had pneumococcal bacteraemia. Compared to blood culture, PCR for lytA, Spn9802 and ply had sensitivities of 70% (7/10), 60% (6/10) and 70% (7/10), and specificities of 96% (79/82), 94% (77/82) and 85% (70/82) respectively. With blood culture and/or culture of representative sputum, and/or urinary antigen detection, S. pneumoniae was identified in 31 CAP patients. Compared to these tests in combination, PCR for lytA, Spn9802 and ply showed sensitivities of 26% (8/31), 32% (10/31) and 42% (13/31), and specificities of 100% (61/61), 98% (60/61) and 90% (55/61) respectively. We conclude that Spn9802 and lytA PCRs may be useful for the rapid detection of bacteraemic pneumococcal pneumonia, whereas ply PCR is not specific enough for routine use and blood PCR with small plasma volumes is not useful for the detection of nonbacteraemic pneumococcal pneumonia.
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| 2. |
- Athlin, Simon, 1971-, et al.
(författare)
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Association between serotype-specific antibody response and serotype characteristics in patients with pneumococcal pneumonia, with special reference to degree of encapsulation and invasive potential
- 2014
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Ingår i: Clinical and Vaccine Immunology. - : American Society for Microbiology. - 1556-6811 .- 1556-679X. ; 21:11, s. 1541-1549
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Tidskriftsartikel (refereegranskat)abstract
- We studied the immunoglobulin (Ig) response to causative serotype-specific capsular polysaccharides in adult pneumococcal pneumonia patients. The serotypes were grouped according to their degree of encapsulation and invasive potential. Seventy patients with pneumococcal pneumonia, 20 of whom were bacteremic, were prospectively studied. All pneumococcal isolates from the patients were serotyped, and the Ig titers to the homologous serotype were determined in acute- and convalescent-phase sera using a serotype-specific enzyme-linked immunosorbent assay. The Ig titers were lower in bacteremic cases than in nonbacteremic cases (P < 0.042). The Ig titer ratio (convalescent/acute titer) was ≥2 in 33 patients, 1 to 1.99 in 20 patients, and <1 in 17 patients. Patients ≥65 years old had a lower median Ig titer ratio than did younger patients (P < 0.031). The patients with serotypes with a thin capsule (1, 4, 7F, 9N, 9V, and 14) and medium/high invasive potential (1, 4, 7F, 9N, 9V, 14, and 18C) had higher Ig titer ratios than did patients with serotypes with a thick capsule (3, 6B, 11A, 18C, 19A, 19F, and 23F) and low invasive potential (3, 6B, 19A, 19F, and 23F) (P < 0.05 for both comparisons after adjustment for age). Ig titer ratios of <1 were predominantly noted in patients with serotypes with a thick capsule. In 8 patients with pneumococcal DNA detected in plasma, the three patients with the highest DNA load had the lowest Ig titer ratios. In conclusion, a high antibody response was associated with serotypes with a thin capsule and medium/high invasive potential, although a low antibody response was associated with serotypes with a thick capsule and a high pneumococcal plasma load.
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| 3. |
- Strålin, Kristoffer, et al.
(författare)
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Comparison of Sputum and Nasopharyngeal Aspirate Samples and of the PCR Gene Targets lytA and Spn9802 for Quantitative PCR for Rapid Detection of Pneumococcal Pneumonia
- 2014
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Ingår i: Journal of Clinical Microbiology. - : American Society for Microbiology. - 0095-1137 .- 1098-660X. ; 52:1, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- We aimed to compare sputum and nasopharyngeal aspirate (NpA) samples and the PCR gene targets lytA and Spn9802 in quantitative PCR (qPCR) assays for rapid detection of pneumococcal etiology in community-acquired pneumonia (CAP). Seventy-eight adult patients hospitalized for radiologically confirmed CAP had both good-quality sputum and NpA specimens collected at admission. These samples were subjected to lytA qPCR and Spn9802 qPCR assays with analytical times of < 3 h. Thirty-two patients had CAP with a pneumococcal etiology, according to conventional diagnostic criteria. The following qPCR positivity rates were noted in CAP cases with and without pneumococcal etiology: 96% and 15% (sputum lytA assay), 96% and 17% (sputum Spn9802 assay), 81% and 11% (NpA lytA assay), and 81% and 20% (NpA Spn9802 assay), respectively. The mean lytA and Spn9802 DNA levels were significantly higher in qPCR-positive sputum samples from cases with pneumococcal etiology than in qPCR-positive sputum samples from CAP cases without pneumococcal etiology or qPCR-positive NpA samples from cases with pneumococcal etiology (P < 0.02 for all comparisons). For detection of pneumococcal etiology, receiver operating characteristic curve analysis showed that sputum specimens were superior to NpA specimens as the sample type (P < 0.02 for both gene targets) and lytA tended to be superior to Spn9802 as the gene target. The best-performing test, the sputum lytA qPCR assay, showed high sensitivity (94%) and specificity (96%) with a cutoff value of 10(5) DNA copies/ml. In CAP patients with good sputum production,
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