K Dirven

Evaluation of 12 Commercial Tests and the Complement Fixation Test for Mycoplasma pneumoniae-Specific Immunoglobulin G (IgG) and IgM Antibodies, with PCR Used as the “Gold Standard”

ABSTRACT Serology and nucleic acid amplification are the main diagnostic tools for the diagnosis of Mycoplasma pneumoniae infection. Since no reference standard is generally accepted, serologic assays for M. pneumoniae have not been evaluated on a broad scale. In this study, 12 commercially available serologic assays (for immunoglobulin G [IgG] and IgM) and the complement fixation test (CFT) were evaluated by using M. pneumoniae DNA detection by real-time PCR as the “gold standard.” The assays tested were Platelia EIA (Bio-Rad), SeroMP EIA (Savyon), Serion classic EIA (Virion/Serion), Biotest EIA (Biotest), Ridascreen EIA (r-Biopharm), AniLabsystems EIA (Labsystems), Novum EIA (Novum Diagnostica), Diagnosys EIA (MP products), Genzyme/Virotech EIA, ImmunoWell EIA (Genbio), ImmunoCard EIA (Meridian), and SerodiaMycoII microparticle agglutination (Fujirebio). Serum samples (n = 46) from 27 PCR-positive patients with a known first day of disease and sera (n = 33) from PCR-negative controls were obtained from prospective studies of acute lower respiratory tract infections. Additionally, control sera (n = 63) from patients with acute viral or bacterial respiratory infections other than those caused by M. pneumoniae were tested. The results showed low specificities for both the Novum and the ImmunoCard IgM assays. The IgM assays with the best performances in terms of sensitivity and specificity were AniLabsystems (77% and 92%, respectively), SeroMP (71% and 88%, respectively), and CFT (65% and 97%, respectively). Good receiver operating characteristic areas under the curve were found for CFT (0.94), the Platelia assay (0.87), and the AniLabsystems assay (0.85). We conclude that there are few commercial serologic assays for the detection of M. pneumoniae infections with appropriate performances in terms of sensitivity and specificity and that PCR has become increasingly important for the diagnosis of M. pneumoniae infections in defined groups of patients.

Detection of Mycoplasma pneumoniae in respiratory samples by real-time PCR using an inhibition control.

Polymerase chain reaction (PCR) with real-time detection using two adjacent fluorescent probes in a Lightcycler instrument was applied for detection of the Mycoplasma pneumoniae P1 protein gene. To monitor inhibition in each sample an internal control was constructed that can be amplified by the same primers but detected by different probes and dual color detection. The real-time PCR was applied on 115 respiratory samples from 82 patients and compared to a conventional PCR. There was 100% agreement between the assays, but the real-time PCR proved to be highly superior in speed with a much lower risk of false positives by laboratory contamination.

What is the role of quality circles in strategies to optimise antibiotic prescribing? A pragmatic cluster-randomised controlled trial in primary care

Objective: To evaluate the effect on antibiotic prescribing of an intervention in existing local quality circles promoting an evidence-based guideline for acute rhinosinusitis. Design: A pragmatic cluster-randomised controlled trial comparing standard dissemination of the guideline by mail with an additional strategy using quality circles. Setting: General practice in Flanders, Belgium. Participants: General practitioners (GPs) in 18 local quality circles were randomly allocated to two study arms. All GPs received the guideline by mail. GPs in the nine quality circles allocated to the intervention arm received an additional group intervention, which consisted of one self-led meeting using material introduced to the group moderator by a member of the research team. Main outcome measures: Adherence to the guideline was measured as differences in the proportion of antibiotic prescriptions, including the choice of antibiotic, between the two study arms after the intervention period. GPs registered their encounters with patients presenting with signs and symptoms of acute rhinosinusitis in a booklet designed for the study. Results: A total of 75 doctors (29% of GPs in the participating quality circles) registered 408 consultations. In the intervention group, 56.9% of patients received an antibiotic compared with 58.3% in the control group. First-choice antibiotics were issued in 34.5% of antibiotic prescriptions in the intervention group compared with 29.4% in the control group. After adjusting for patient and GP characteristics, the ORadj for antibiotics prescribed in the intervention arm compared with the control arm was 0.63 (95% CI 0.29 to 1.37). There was no effect on the choice of antibiotic (ORadj 1.07, 95% CI 0.34 to 3.37). Conclusion: A single intervention in quality circles of GPs integrated in the group’s normal working procedure did not have a significant effect on the quality of antibiotic prescribing. More attention to the context and structure of primary care practice, and insight into the process of self-reflective learning may provide clues to optimise the effectiveness of quality circles.

An outbreak of Legionnaire's disease among visitors to a fair in Belgium in 1999

This paper describes an outbreak of Legionnaires disease at Kapellen in Belgium among visitors of the annual fair. The investigation started on 13th November 1999 after a respiratory physician notified the health authorities of the province of Antwerp of presumptive cases of legionellosis. The annual commercial fair at Kapellen, a small town in northern Belgium, was held 10 days previously and attracted 50,000 visitors. Stand employees (professionals or volunteers), technical staff of the hall and visitors at the fair were affected cases. An exploratory case-control study was conducted to trace the source of the epidemic. To complete the inventory study and to evaluate other risk factors, a cohort study of exhibitors and staff was conducted. Ninety-three people met the case definition, 41 of whom were considered as confirmed, 14 as presumptive cases and 38 as possible/clinical cases. Five people died. Further testing at the reference laboratory confirmed all strains to be Legionella pneumophila serogroup 1. The sensitivity for culture was low (29.2%), and sensitivity for seroconversion was high (90.9%). For urinary antigen test, a sensitivity with Biotest EIA of 65.6% was found, and the sensitivity of polymerase chain reaction (PCR) was 85.7%. In all cases, the individual had visited the fair. Those individuals working in the central areas of the tent, near the aerosol-producing devices, were at higher risk of disease. Legionella was detected by PCR on swabs of the surfaces of the whirlpool. Although not fully proven, an aerosol-producing device was the most probable source of the outbreak.