Dataset Information

Use of a rapid test of pneumococcal colonization density to diagnose pneumococcal pneumonia.

ABSTRACT:

Background

There is major need for a more sensitive assay for the diagnosis of pneumococcal community-acquired pneumonia (CAP). We hypothesized that pneumococcal nasopharyngeal (NP) proliferation may lead to microaspiration followed by pneumonia. We therefore tested a quantitative lytA real-time polymerase chain reaction (rtPCR) on NP swab samples from patients with pneumonia and controls.

Methods

In the absence of a sensitive reference standard, a composite diagnostic standard for pneumococcal pneumonia was considered positive in South African human immunodeficiency virus (HIV)-infected adults hospitalized with radiographically confirmed CAP, if blood culture, induced good-quality sputum culture, Gram stain, or urinary Binax demonstrated pneumococci. Results of quantitative lytA rtPCR in NP swab samples were compared with quantitative colony counts in patients with CAP and 300 HIV-infected asymptomatic controls.

Results

Pneumococci were the leading pathogen identified in 76 of 280 patients with CAP (27.1%) using the composite diagnostic standard. NP colonization density measured by lytA rtPCR correlated with quantitative cultures (r = 0.67; P < .001). The mean lytA rtPCR copy number in patients with pneumococcal pneumonia was 6.0 log(10) copies/mL, compared with patients with CAP outside the composite standard (2.7 log(10) copies/mL; P < .001) and asymptomatic controls (0.8 log(10) copies/mL; P < .001). A lytA rtPCR density ?8000 copies/mL had a sensitivity of 82.2% and a specificity of 92.0% for distinguishing pneumococcal CAP from asymptomatic colonization. The proportion of CAP cases attributable to pneumococcus increased from 27.1% to 52.5% using that cutoff.

Conclusions

A rapid molecular assay of NP pneumococcal density performed on an easily available specimen may significantly increase pneumococcal pneumonia diagnoses in adults.

SUBMITTER: Albrich WC

PROVIDER: S-EPMC3275757 | biostudies-literature | 2012 Mar

REPOSITORIES: biostudies-literature

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Publications

Use of a rapid test of pneumococcal colonization density to diagnose pneumococcal pneumonia.

Albrich W C WC Madhi S A SA Adrian P V PV van Niekerk N N Mareletsi T T Cutland C C Wong M M Khoosal M M Karstaedt A A Zhao P P Deatly A A Sidhu M M Jansen K U KU Klugman K P KP

Clinical infectious diseases : an official publication of the Infectious Diseases Society of America 20111208 5

<h4>Background</h4>There is major need for a more sensitive assay for the diagnosis of pneumococcal community-acquired pneumonia (CAP). We hypothesized that pneumococcal nasopharyngeal (NP) proliferation may lead to microaspiration followed by pneumonia. We therefore tested a quantitative lytA real-time polymerase chain reaction (rtPCR) on NP swab samples from patients with pneumonia and controls.<h4>Methods</h4>In the absence of a sensitive reference standard, a composite diagnostic standard fo ...[more]

PMID: 22156852

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Project description:Background.Previous studies suggested an association between upper airway pneumococcal colonization density and pneumococcal pneumonia, but data in children are limited. Using data from the Pneumonia Etiology Research for Child Health (PERCH) study, we assessed this potential association.Methods.PERCH is a case-control study in 7 countries: Bangladesh, The Gambia, Kenya, Mali, South Africa, Thailand, and Zambia. Cases were children aged 1-59 months hospitalized with World Health Organization-defined severe or very severe pneumonia. Controls were randomly selected from the community. Microbiologically confirmed pneumococcal pneumonia (MCPP) was confirmed by detection of pneumococcus in a relevant normally sterile body fluid. Colonization density was calculated with quantitative polymerase chain reaction analysis of nasopharyngeal/oropharyngeal specimens.Results.Median colonization density among 56 cases with MCPP (MCPP cases; 17.28 × 106 copies/mL) exceeded that of cases without MCPP (non-MCPP cases; 0.75 × 106) and controls (0.60 × 106) (each P < .001). The optimal density for discriminating MCPP cases from controls using the Youden index was >6.9 log10 copies/mL; overall, the sensitivity was 64% and the specificity 92%, with variable performance by site. The threshold was lower (≥4.4 log10 copies/mL) when MCPP cases were distinguished from controls who received antibiotics before specimen collection. Among the 4035 non-MCPP cases, 500 (12%) had pneumococcal colonization density >6.9 log10 copies/mL; above this cutoff was associated with alveolar consolidation at chest radiography, very severe pneumonia, oxygen saturation <92%, C-reactive protein ≥40 mg/L, and lack of antibiotic pretreatment (all P< .001).Conclusions.Pneumococcal colonization density >6.9 log10 copies/mL was strongly associated with MCPP and could be used to improve estimates of pneumococcal pneumonia prevalence in childhood pneumonia studies. Our findings do not support its use for individual diagnosis in a clinical setting.

Project description:BackgroundPharyngitis management guidelines include estimates of the test characteristics of rapid antigen streptococcus tests (RAST) using a non-systematic approach.ObjectiveTo examine the sensitivity and specificity, and sources of variability, of RAST for diagnosing group A streptococcal (GAS) pharyngitis.Data sourcesMEDLINE, Cochrane Reviews, Centre for Reviews and Dissemination, Scopus, SciELO, CINAHL, guidelines, 2000-2012.Study selectionCulture as reference standard, all languages.Data extraction and synthesisStudy characteristics, quality.Main outcome(s) and measure(s)Sensitivity, specificity.ResultsWe included 59 studies encompassing 55,766 patients. Forty three studies (18,464 patients) fulfilled the higher quality definition (at least 50 patients, prospective data collection, and no significant biases) and 16 (35,634 patients) did not. For the higher quality immunochromatographic methods in children (10,325 patients), heterogeneity was high for sensitivity (inconsistency [I(2)] 88%) and specificity (I(2) 86%). For enzyme immunoassay in children (342 patients), the pooled sensitivity was 86% (95% CI, 79-92%) and the pooled specificity was 92% (95% CI, 88-95%). For the higher quality immunochromatographic methods in the adult population (1,216 patients), the pooled sensitivity was 91% (95% CI, 87 to 94%) and the pooled specificity was 93% (95% CI, 92 to 95%); however, heterogeneity was modest for sensitivity (I(2) 61%) and specificity (I(2) 72%). For enzyme immunoassay in the adult population (333 patients), the pooled sensitivity was 86% (95% CI, 81-91%) and the pooled specificity was 97% (95% CI, 96 to 99%); however, heterogeneity was high for sensitivity and specificity (both, I(2) 88%).ConclusionsRAST immunochromatographic methods appear to be very sensitive and highly specific to diagnose group A streptococcal pharyngitis among adults but not in children. We could not identify sources of variability among higher quality studies. The present systematic review provides the best evidence for the wide range of sensitivity included in current guidelines.

Dataset Information

Use of a rapid test of pneumococcal colonization density to diagnose pneumococcal pneumonia.

Background

Methods

Results

Conclusions

Publications

Use of a rapid test of pneumococcal colonization density to diagnose pneumococcal pneumonia.

Similar Datasets

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