Alma C. van de Pol

Increased Detection of Respiratory Syncytial Virus, Influenza Viruses, Parainfluenza Viruses, and Adenoviruses with Real-Time PCR in Samples from Patients with Respiratory Symptoms

ABSTRACT Respiratory samples (n = 267) from hospitalized patients with respiratory symptoms were tested by real-time PCR, viral culture, and direct immunofluorescence for respiratory syncytial virus, influenza virus, parainfluenza viruses, and adenoviruses. Compared with conventional diagnostic tests, real-time PCR increased the diagnostic yields for these viruses from 24% to 43% and from 3.5% to 36% for children and adults, respectively.

A Systemic Neutrophil Response Precedes Robust CD8+ T-Cell Activation during Natural Respiratory Syncytial Virus Infection in Infants

ABSTRACT Severe primary respiratory syncytial virus (RSV) infections are characterized by bronchiolitis accompanied by wheezing. Controversy exists as to whether infants suffer from virus-induced lung pathology or from excessive immune responses. Furthermore, detailed knowledge about the development of primary T-cell responses to viral infections in infants is lacking. We studied the dynamics of innate neutrophil and adaptive T-cell responses in peripheral blood in relation to theviral load and parameters of disease in infants admitted to the intensive care unit with severe RSV infection. Analysis of primary T-cell responses showed substantial CD8+ T-cell activation, which peaked during convalescence. A strong neutrophil response, characterized by mobilization of bone marrow-derived neutrophil precursors, preceded the peak in T-cell activation. The kinetics of this neutrophil response followed the peak of clinical symptoms and the viral load with a 2- to 3-day delay. From the sequence of events, we conclude that CD8+ T-cell responses, initiated during primary RSV infections, are unlikely to contribute to disease when it is most severe. The mobilization of precursor neutrophils might reflect the strong neutrophil influx into the airways, which is a characteristic feature during RSV infections and might be an integral pathogenic process in the disease.

Diagnostic value of real-time polymerase chain reaction to detect viruses in young children admitted to the paediatric intensive care unit with lower respiratory tract infection

IntroductionThe aetiology of lower respiratory tract infections in young children admitted to the paediatric intensive care unit (PICU) is often difficult to establish. However, most infections are believed to be caused by respiratory viruses. A diagnostic study was performed to compare conventional viral tests with the recently developed real-time PCR technique.MethodSamples from children aged under 5 years presenting to a tertiary PICU suspected of having a lower respiratory tract infection were tested using conventional methods (viral culture and immunofluorescence) and real-time PCR during the winter season from December 2004 to May 2005. Conventional methods were used to check for respiratory syncytial virus, influenzavirus, parainfluenzavirus 1–3, rhinoviruses and adenoviruses. Real-time PCR was used to test for respiratory syncytial virus, influenzavirus, parainfluenzavirus 1–4, rhinoviruses, adenoviruses, human coronaviruses OC43, NL63 and 229E, human metapneumovirus, Mycoplasma pneumoniae and Chlamydia pneumoniae.ResultsA total of 23 patients were included, of whom 11 (48%) were positive for a respiratory virus by conventional methods. Real-time PCR confirmed all of these positive results. In addition, real-time PCR identified 22 more viruses in 11 patients, yielding a total of 22 (96%) patients with a positive sample. More than one virus was detected in eight (35%) children.ConclusionReal-time PCR for respiratory viruses was found to be a sensitive and reliable method in PICU patients with lower respiratory tract infection, increasing the diagnostic yield twofold compared to conventional methods.

Human Bocavirus and KI/WU Polyomaviruses in Pediatric Intensive Care Patients

We evaluated the prevalence of human bocavirus and KI and WU polyomaviruses in pediatric intensive care patients with and without lower respiratory tract infection (LRTI). The prevalence of these viruses was 5.1%, 0%, and 2.6%, respectively, in children with LRTI and 4.8%, 4.8%, and 2.4%, respectively, in those without LRTI.

Proteins involved in extracellular matrix dynamics are associated with respiratory syncytial virus disease severity

Severity of respiratory syncytial virus (RSV) infection ranges widely. To what extent the local immune response is involved in RSV disease pathogenesis and which markers of this response are critical in determining disease severity is still a matter of debate. The local immune response was studied in nasopharyngeal aspirates (NPAs) during RSV infection. 47 potential markers of disease severity were analysed in a screening cohort of RSV-infected infants with mild disease at home (n=8), hospitalised infants (n=10) and infants requiring mechanical ventilation (n=7). Results were confirmed in a cohort of infants hospitalised for RSV infection (n=200). Finally, genetic validation was studied in a cohort of infants hospitalised for RSV infection (n=465) and healthy controls (n=930). The concentration of TIMP-1 (tissue inhibitor of metalloproteinase) was higher in the NPAs of hospitalised infants compared with the NPAs of infants at home (1,199 versus 568 ng·mL−1; p<0.0001). Similar results were found for matrix metalloproteinase (MMP)-3 (765 versus 370 pg·mL−1; p=0.004). MMP-3 was confirmed as a marker of disease severity in a larger cohort and MMP3 gene polymorphism rs522616 was associated with severe RSV infection (OR 0.82, p<0.05). In conclusion, extracellular matrix proteinases play an important role in the pathogenesis of RSV bronchiolitis.

Molecular Quantification of Respiratory Syncytial Virus in Respiratory Samples: Reliable Detection during the Initial Phase of Infection

ABSTRACT Quantitative real-time PCR for the detection of respiratory syncytial virus (RSV) RNA is increasingly used to study the causal role of RSV in lower airway disease. The objective of our study was to evaluate variations in RSV RNA loads at different steps in the RNA quantification process: (i) variation in RSV RNA load within one sample (step 1), (ii) variation in the load in samples from patients who were sampled twice on the same day (step 2), and (iii) variation in the load between simultaneously taken nasopharyngeal aspirate (NPA) samples and tracheal aspirate (TA) samples (step 3). Thirty-two infants with RSV infection at the pediatric intensive care unit (PICU) were included. NPA and TA samples were taken three times a week during ventilation and were not diluted. Intrasample variation (step 1) was shown to be minimal (<0.5 log10 particles/ml). Intraday variation (step 2) was the lowest for samples with high viral loads (95% limits of agreement, −1.3 to +0.9 log10), whereas it increased for samples with relatively lower viral loads (viral load, <6.0 log10 particles/ml; n = 138 sample pairs from 20 patients). RSV loads in NPA and TA samples (step 3) were found to be the most comparable during the early phase of infection (95% limits of agreement, −1.5 to +1.4 log10). The variation increased during the late phase of infection (i.e., in follow-up samples), with the loads in NPA samples remaining significantly higher than the loads in TA samples (n = 138 sample pairs from 31 patients). In conclusion, quantitative detection of RSV RNA in undiluted mucus is a reliable method to quantify viral loads. Nasopharyngeal aspirate samples collected in the initial phase of infection can be used to predict RSV RNA loads in the lower airways.

Referrals for recurrent respiratory tract infections including otitis media in young children.

OBJECTIVE (a) To establish whether disease-related, child-related, and physician-related factors are independently associated with specialist referral in young children with recurrent RTI, and (b) to evaluate whether general practitioners (GPs) follow current guidelines regarding these referrals. METHODS Electronic GP records of children under 24 month of age, born 2002-2008, were reviewed for RTI episodes using ICPC codes. Child-related factors were extracted from the prospective WHISTLER birth-cohort in which a considerable part of children had been enrolled. To evaluate guideline adherence, referral data were compared to national guideline recommendations. RESULTS Consultations for 2532 RTI episodes (1041 children) were assessed. Seventy-eight children were referred for recurrent RTI (3.1% of RTI episodes; 7.5% of children). Disease factors were the main determinants of referral: number (OR 1.7 [CI 1.7-1.7]) and severity of previous RTI episodes (OR 2.2 [CI 1.6-2.8]), and duration of RTI episode (OR 1.7 [CI 1.7-1.8]). The non-disease factors daycare attendance (OR 1.3 [CI 1.0-1.7]) and 5-10 years working experience as a GP compared with <5 years (OR 0.37 [CI 0.27-0.50]) were also associated. Fifty-seven percent of referrals for recurrent RTI were made in accordance with national guidelines. CONCLUSIONS Referral of children for recurrent RTI was primarily determined by frequency, severity, and duration of RTIs; the influence of non-disease factors was limited. Just over half of referrals were made in accordance with guidelines.

The added value of C-reactive protein measurement in diagnosing pneumonia in primary care: a meta-analysis of individual patient data

BACKGROUND: C-reactive protein (CRP) is increasingly being included in the diagnostic work-up for community-acquired pneumonia in primary care. Its added diagnostic value beyond signs and symptoms, however, remains unclear. We conducted a meta-analysis of individual patient data to quantify the added value of CRP measurement. METHODS: We included studies of the diagnostic accuracy of CRP in adult outpatients with suspected lower respiratory tract infection. We contacted authors of eligible studies for inclusion of data and for additional data as needed. The value of adding CRP measurement to a basic signs-and-symptoms prediction model was assessed. Outcome measures were improvement in discrimination between patients with and without pneumonia in primary care and improvement in risk classification, both within the individual studies and across studies. RESULTS: Authors of 8 eligible studies (n = 5308) provided their data sets. In all of the data sets, discrimination between patients with and without pneumonia improved after CRP measurement was added to the prediction model (extended model), with a mean improvement in the area under the curve of 0.075 (range 0.02–0.18). In a hypothetical cohort of 1000 patients, the proportion of patients without pneumonia correctly classified at low risk increased from 28% to 36% in the extended model, and the proportion with pneumonia correctly classified at high risk increased from 63% to 70%. The number of patients with pneumonia classified at low risk did not change (n = 4). Overall, the proportion of patients assigned to the intermediate-risk category decreased from 56% to 51%. INTERPRETATION: Adding CRP measurement to the diagnostic work-up for suspected pneumonia in primary care improved the discrimination and risk classification of patients. However, it still left a substantial group of patients classified at intermediate risk, in which clinical decision-making remains challenging.

The added diagnostic value of five different C-reactive protein point-of-care test devices in detecting pneumonia in primary care: A nested case-control study

Abstract Background. The results obtained from various point-of-care (POC) test devices for estimating C-reactive protein (CRP) levels in a laboratory setting differ when compared to a laboratory reference test. We aimed to determine whether such differences meaningfully affect the accuracy and added diagnostic value in predicting radiographic pneumonia in adults presenting with acute cough in primary care. Methods. A nested case control study of adult patients presenting with acute cough in 12 different European countries (the Genomics to combat Resistance against Antibiotics in Community-acquired LRTI in Europe [GRACE] Network). Venous blood samples from 100 patients with and 100 patients without pneumonia were tested with five different POC CRP tests and a laboratory analyzer. Single test accuracy values and the added value of CRP to symptoms and signs were calculated. Results. Single test accuracy values showed similar results for all five POC CRP tests and the laboratory analyzer. The area under the curve of the different POC CRP tests and the laboratory analyzer (range 0.79–0.80) were all comparable and higher than the clinical model without CRP (0.70). Multivariable odds ratios were the same (1.2) for all CRP tests. Conclusions. Five POC CRP test devices and the laboratory analyzer performed with similar accuracy in detecting pneumonia both as single test, and when used in addition to clinical findings. Variability in results obtained from standard CRP laboratory and POC test devices do not translate into clinically relevant differences when used for prediction of pneumonia in patients with acute cough in primary care.

Suspected cow’s milk allergy in everyday general practice: a retrospective cohort study on health care burden and guideline adherence

BackgroundCow’s milk allergy (CMA) is the most common food allergy among infants. No data are available on the health care burden of suspected CMA in general practice. This study was conducted to evaluate the burden of suspected CMA in general practice (GP): (a) prevalence, (b) presenting symptoms, (c) diagnostic process, (d) guideline adherence, and (e) dietary measures.MethodsA retrospective cohort study was carried out in four Julius Healthcare Centers (JHCs). These JHCs form the core primary care academic network of the department of general practice of the University Medical Center of Utrecht. Electronic records of the first year of infants born May 2009 - April 2010 registered in the JHCs were screened for possible CMA suspicion. Preventive child healthcare (PCH) records were reviewed for additional information. Clinical presentation, diagnostic strategies and dietary measures were extracted.ResultsOf 804 infants evaluated, 55 presented with symptoms fitting the suspicion of CMA (prevalence of 7%). Presenting complaints involved the skin (71%); the gastrointestinal tract (60%); the respiratory tract (13%) or other symptoms (36%) and 23 infants presented with symptoms of two or more organ systems. In 31 children (56%) a food challenge was performed (n = 28 open and n = 3 double-blind). Open challenge test results were difficult to interpret due to inadequate implementation or reporting. None had confirmed CMA after an adequate challenge test. Long term milk substitute formulas were prescribed in 39 (71%) infants.ConclusionOn a yearly basis seven percent of children visit their GP for suspected CMA. A positive CMA diagnosis was rarely established after adequate implementation and reporting of diagnostics, yet long term dietary measures were prescribed in >70% of patients. There is definitely need for improvement of diagnosing CMA in primary care.