[show abstract][hide abstract] ABSTRACT: Observational studies have reported an inverse association between serum 25-hydroxyvitamin D (25OHD) concentrations and Staphylococcus aureus nasal carriage; however, clinical trials of vitamin D supplementation are lacking. To assess the effect of vitamin D3 supplementation on persistent S. aureus nasal carriage we conducted a randomized, double-blind, placebo-controlled trial among 322 healthy adults. Participants were given an oral dose of either 200 000 IU vitamin D3 for each of 2 months, followed by 100 000 IU monthly or placebo in an identical dosing regimen, for a total of 18 months. Nasal swabs for S. aureus culture and serum for 25OHD measurement were obtained at baseline, 6, 12 and 18 months of study. The mean baseline concentration of 25OHD was 72 nM (SD 22 nM). Vitamin D3 supplementation increased 25OHD levels which were maintained at >120 nM throughout the study. Nasal colonization by S. aureus was found in 31% of participants at baseline. Persistent carriage, defined as those that had positive S. aureus nasal cultures for all post-baseline swabs, occurred in 20% of the participants but vitamin D3 supplementation was not associated with a reduction in persistent carriage (OR = 1.39, 95% CI 0.63-3.06). Risk factor analysis showed that only gender was significantly associated with carriage, where women were less likely to be carriers than men (relative risk 0.83, 95% CI 0.54-0.99). Serum 25OHD concentrations were not associated with the risk of carriage. In conclusion, monthly administration of 100 000 IU of vitamin D3 did not reduce persistent S. aureus nasal carriage.
Clinical Microbiology and Infection 07/2013; · 4.58 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background. Legionnaires' disease cannot be clinically or radiographically distinguished from other causes of pneumonia, and specific tests are required to make the diagnosis. Currently, testing occurs erratically and, instead, clinicians rely on empiric treatment strategies and ignore public health implications of the diagnosis. We aimed to measure the increase in case detection of legionnaires' disease following the introduction of routine PCR testing of respiratory specimens. PCR is the most sensitive diagnostic tool for legionnaires' disease. Methods. In a quasi-experimental study in Christchurch, New Zealand, we compared the number of hospitalized cases of legionnaires' disease diagnosed during a two-year period before the introduction of a routine PCR testing strategy (November 2008 to October 2010) with a similar period after the introduction (November 2010 to October 2012). With this testing strategy, all respiratory specimens from hospitalized patients with pneumonia sent to the region's sole tertiary-level laboratory were tested for Legionella by PCR, whether requested or not. Results. During November 2008 to October 2010 there were 22 cases of legionnaires' disease compared with 92 during November 2010 to October 2012. Of 1834 samples tested since November 2010, 1 in 20 was positive, increasing to 1 in 9 during peak Legionella season (November to January). Increasing bacterial load was associated with increasing disease severity. Conclusion. In our region, the burden of legionnaires' disease is much greater than was previously recognized. Routine PCR testing provides results within a clinically-relevant time frame and enables improved characterization of the regional epidemiology of legionnaires' disease.
[show abstract][hide abstract] ABSTRACT: OBJECTIVES: To determine whether systematic testing of faecal samples with a broad range multiplex PCR increases the diagnostic yield in patients with diarrhoea compared with conventional methods and a clinician initiated testing strategy. METHODS: 1758 faecal samples from 1516 patients with diarrhoea submitted to two diagnostic laboratories were tested for viral, bacterial, and parasitic pathogens by Fast-Track Diagnostics multiplex real-time PCR kits and conventional diagnostic tests. RESULTS: Multiplex PCR detected pathogens in 530 samples (30%): adenovirus (51, 3%), astrovirus (95, 5%), norovirus (172, 10%), rotavirus (3, 0.2%), Campylobacter jejuni/coli (85, 5%), Salmonella spp. (22, 1%), Clostridium difficile (72, 4%), entero-haemorrhagic Escherichia coli (21, 1%), Cryptosporidium spp. (3, 0.2%), Entamoeba histolytica (1, 0.1%), and Giardia lamblia (59, 3%). In contrast, conventional testing detected a pathogen in 324 (18%) samples. CONCLUSIONS: Using a systematic approach to the diagnosis of gastroenteritis improved diagnostic yield. This enhanced detection with PCR was achieved by a combination of improved detection of individual pathogens and detection of pathogens not requested or unable to be tested by conventional tests. This approach also allowed earlier identification for most pathogens and created a workflow which is likely to adapt well for many diagnostic laboratories.
The Journal of infection 04/2013; · 4.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: The Vi capsular polysaccharide (ViPS) protects Salmonella enterica subspecies enterica serotype Typhi (S.Typhi) in vivo by multiple mechanisms. Recent microbiological reports from typhoid endemic countries suggest that acapsulate S.Typhi may occur in nature and contribute to clinical typhoid fever that is indistinguishable from disease caused by capsulate strains. The prevalence and genetic basis of ViPS-negative S.Typhi isolates in children from Kathmandu, Nepal, were tested in 68 isolates. Although 5.9% of isolates tested negative for capsular expression by slide agglutination tests, a novel multiplex PCR assay and individual PCR analyses demonstrated the presence of all 14 genes responsible for the synthesis, transportation and regulation of the ViPS. These data suggest that phenotypically acapsulate S.Typhi may not have a genetic basis for the same.
Journal of Tropical Pediatrics 04/2013; · 1.01 Impact Factor
[show abstract][hide abstract] ABSTRACT: Multiplex PCR has become the test of choice for the detection of multiple respiratory viruses in clinical specimens. However, there are few direct comparisons of different PCR assays. This study compares 4 different multiplex PCR assays for the recovery of common respiratory viruses. We tested 213 respiratory specimens using four different multiplex PCR assays: the xTAG respiratory viral panel fast (Abbott Molecular Laboratories), Fast-track Respiratory Pathogen assay (Fast-track Diagnostics), Easyplex respiratory pathogen 12 kit (Ausdiagnostics), and an in-house multiplex real-time PCR assay. The performance of the four assays was very similar, with 93-100% agreement for all comparisons. Other issues, such as through-put, technical requirements and cost, are likely to be as important for making a decision about which of these assays to use given their comparative performance.
Journal of virological methods 04/2013; · 2.13 Impact Factor
[show abstract][hide abstract] ABSTRACT: A suite of volatiles have previously been identified as specific markers of Mycobacterium tuberculosis metabolism in vitro. These markers - methyl phenylacetate, methyl p-anisate, methyl nicotinate, o-phenylanisole with the addition of methyl salicylate, may also be derived from other sources and confound development of a breath test for tuberculosis. To identify potential sources of these potential biomarkers food products, cosmetics, TB medication, environmental air and cigarette smoke were analysed for these markers using solid phase microextraction coupled with Gas Chromatography/Mass Spectrometry. Breath from healthy subjects, including smokers was also tested. Methyl salicylate was commonly detected, making this unsuitable as a specific marker for M. tuberculosis. Methyl nicotinate was detected repeatedly in cigarettes. Methyl phenylacetate was detected in 1.7% of healthy subjects and o-phenylanisole in just 1% of healthy breath indicating these may be more suitable for inclusion in the tuberculosis breath test due to their low "background" level. These results justify further clinical studies to further explore these markers as specific indicators of M. tuberculosis infection.
[show abstract][hide abstract] ABSTRACT: Cardiac dysfunction is common in acute respiratory diseases and may influence prognosis. We hypothesised that blood levels of N-terminal B-type natriuretic peptide (NT-proBNP) and high-sensitivity Troponin T would predict mortality in adults with community-acquired pneumonia.
A prospective cohort of 474 consecutive patients admitted with community-acquired pneumonia to two New Zealand hospitals over one year. Blood taken on admission was available for 453 patients and was analysed for NT-proBNP and Troponin T. Elevated levels of NT-proBNP (>220 pmol/L) were present in 148 (33%) and 86 (19%) of these patients respectively. Among the 26 patients who died within 30 days of admission, 23 (89%) had a raised NT-proBNP and 14 (53%) had a raised Troponin T level on admission compared to 125 (29%) and 72 (17%) of the 427 who survived (p values<0.001). Both NT-proBNP and Troponin T predicted 30-day mortality in age-adjusted analysis but after mutual adjustment for the other cardiac biomarker and the Pneumonia Severity Index, a raised N-terminal pro-brain natriuretic peptide remained a predictor of 30-day mortality (OR = 5.3, 95% CI 1.4-19.8, p = 0.013) but Troponin T did not (OR = 1.3, 95% CI 0.5-3.2, p = 0.630). The areas under the receiver-operating curves to predict 30-day mortality were similar for NT-proBNP (0.88) and the Pneumonia Severity Index (0.87).
Elevated N-terminal B-type natriuretic peptide is a strong predictor of mortality from community-acquired pneumonia independent of clinical prognostic indicators. The pathophysiological basis for this is unknown but suggests that cardiac involvement may be an under-recognised determinant of outcome in pneumonia and may require a different approach to treatment. In the meantime, measurement of B-type natriuretic peptides may help to assess prognosis.
PLoS ONE 01/2013; 8(5):e62612. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Observational studies have reported an inverse association between serum 25-hydroxyvitamin D (25-OHD) levels and incidence of upper respiratory tract infections (URTIs). However, results of clinical trials of vitamin D supplementation have been inconclusive.
To determine the effect of vitamin D supplementation on incidence and severity of URTIs in healthy adults.
Randomized, double-blind, placebo-controlled trial conducted among 322 healthy adults between February 2010 and November 2011 in Christchurch, New Zealand.
Participants were randomly assigned to receive an initial dose of 200,000 IU oral vitamin D3, then 200,000 IU 1 month later, then 100,000 IU monthly (n = 161), or placebo administered in an identical dosing regimen (n = 161), for a total of 18 months.
The primary end point was number of URTI episodes. Secondary end points were duration of URTI episodes, severity of URTI episodes, and number of days of missed work due to URTI episodes.
The mean baseline 25-OHD level of participants was 29 (SD, 9) ng/mL. Vitamin D supplementation resulted in an increase in serum 25-OHD levels that was maintained at greater than 48 ng/mL throughout the study. There were 593 URTI episodes in the vitamin D group and 611 in the placebo group, with no statistically significant differences in the number of URTIs per participant (mean, 3.7 per person in the vitamin D group and 3.8 per person in the placebo group; risk ratio, 0.97; 95% CI, 0.85-1.11), number of days of missed work as a result of URTIs (mean, 0.76 days in each group; risk ratio, 1.03; 95% CI, 0.81-1.30), duration of symptoms per episode (mean, 12 days in each group; risk ratio, 0.96; 95% CI, 0.73-1.25), or severity of URTI episodes. These findings remained unchanged when the analysis was repeated by season and by baseline 25-OHD levels.
In this trial, monthly administration of 100,000 IU of vitamin D did not reduce the incidence or severity of URTIs in healthy adults.
anzctr.org.au Identifier: ACTRN12609000486224.
JAMA The Journal of the American Medical Association 10/2012; 308(13):1333-9. · 29.98 Impact Factor
[show abstract][hide abstract] ABSTRACT: The differentiation of species within the Streptococcus mitis group has posed a problem in the routine diagnostic microbiology laboratory for some time. It also constitutes a major weakness of recently introduced matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) fingerprinting systems. As the phylogenetic resolution of the spectral similarity measures employed by these systems is insufficient to reliably distinguish between the most closely related members of the group, the major pathogen Streptococcus pneumoniae is frequently misidentified. In this study, a comparative analysis of MALDI-TOF spectra of several species from the S. mitis group has been performed in order to identify single peaks that could be used to improve mass spectrometry-based identification of the respective species. A characteristic peak profile could be identified that unambiguously distinguished the 14 S. pneumoniae isolates studied from 33 nonpneumococcal isolates of the S. mitis group. In addition, specific peak combinations could be assigned to other members of the group. The findings of this study suggest that it is possible to distinguish different species of the S. mitis group by close analysis of their mass peak profiles.
Journal of clinical microbiology 06/2012; 50(9):2863-7. · 4.16 Impact Factor
[show abstract][hide abstract] ABSTRACT: In this study four monoclonal antibodies (MAbs) and two polyclonal antisera were raised against pneumococcal surface adhesion A (psaA), a 37 kDa cell wall protein, and were characterized. The MAbs were purified, isotyped, and epitope mapped with peptide microarrays. All monoclonals and polyclonals underwent testing in immunodot blot, Western blot, and ELISA assays to assess their specificity. All monoclonal antibodies belonged to isotype IgG1 κ. Peptide microarray mapping identified two likely epitopes, which could not be confirmed using synthetic peptides of the identified amino acid sequence. All four MAbs detected the 53 pneumococcal serotypes tested in the immunodot blot and only reacted with Streptococcus pseudopneumoniae in cross-reactivity studies by Western blot. The polyclonal antisera also recognized all tested pneumococcal serotypes and cross-reacted with S. pseudopneumoniae and Streptococcus oralis by Western blot. The MAbs cross-reacted with S. pseudopneumoniae in the ELISA. Both polyclonal antisera cross-reacted with all isolates tested in the ELISA. These antisera should be suitable to establish a diagnostic ELISA platform for pneumococcal antigen detection with polyclonal antisera as the capture antibody. The specificity of the four MAbs appears to be high as they only recognized S. pneumoniae and S. pseudopneumoniae. However, further testing of closely related streptococcal species is necessary to confirm this finding.
[show abstract][hide abstract] ABSTRACT: The global epidemiology of infective endocarditis is becoming better understood with the initiation of multi-center collaborative studies and with an increasing number of case series being reported from countries outside North America and Europe. However, there are still many knowledge gaps and a lack of population-based data. For endocarditis in developed countries, the role of rheumatic heart disease as a predisposing factor is diminishing; the population is increasingly elderly, staphylococci are becoming much more important pathogens, and proportionally more are healthcare-associated. In developing countries, the epidemiology of infective endocarditis remains similar to North America and Europe from the middle of the twentieth century, affecting a younger age group, is often associated with rheumatic heart disease, and is predominantly caused by streptococci.
Current Infectious Disease Reports 05/2012; 14(4):367-72.
[show abstract][hide abstract] ABSTRACT: Determination of pneumococcal load by quantitative PCR may be useful for diagnostic and prognostic purposes. We hypothesized that higher pneumococcal load would be associated with increased pneumonia severity. Therefore, we tested serum, sputum and urine specimens from 304 adults with community-acquired pneumonia by using a quantitative lytA pneumococcal real-time PCR assay. The association between pneumococcal load and disease severity was assessed using several markers of severity: CURBage score, PSI risk class, intensive care unit admission, in-hospital death and admission duration. For PCR-positive specimens, the bacterial loads were higher in sputum specimens [median 8.55×10(5) copies ml(-1); interquartile range (IQR) 4.70×10(4)-4.69×10(6) copies ml(-1)] than either serum (median 180 copies ml(-1); IQR 165-8970 copies ml(-1)) or urine (median 623 copies ml(-1); IQR 510-650 copies ml(-1)). Detection of pneumococcal DNA in serum was associated with severe disease, and there was evidence of a dose-response effect with increased bacterial load being associated with increased severity. The same observations were not observed for other specimen types. This study adds to an increasing body of evidence suggesting that determination of pneumococcal load has a clinical utility. Further work is needed to determine whether measuring pneumococcal load in respiratory specimens from adults will differentiate colonization from coincidental carriage.
Journal of Medical Microbiology 04/2012; 61(Pt 8):1129-35. · 2.30 Impact Factor
[show abstract][hide abstract] ABSTRACT: To develop a case definition for the Pneumonia Etiology Research for Child Health (PERCH) project, we sought a widely acceptable classification that was linked to existing pneumonia research and focused on very severe cases. We began with the World Health Organization's classification of severe/very severe pneumonia and refined it through literature reviews and a 2-stage process of expert consultation. PERCH will study hospitalized children, aged 1-59 months, with pneumonia who present with cough or difficulty breathing and have either severe pneumonia (lower chest wall indrawing) or very severe pneumonia (central cyanosis, difficulty breastfeeding/drinking, vomiting everything, convulsions, lethargy, unconsciousness, or head nodding). It will exclude patients with recent hospitalization and children with wheeze whose indrawing resolves after bronchodilator therapy. The PERCH investigators agreed upon standard interpretations of the symptoms and signs. These will be maintained by a clinical standardization monitor who conducts repeated instruction at each site and by recurrent local training and testing.
[show abstract][hide abstract] ABSTRACT: As a case-control study of etiology, the Pneumonia Etiology Research for Child Health (PERCH) project also provides an opportunity to assess the risk factors for severe pneumonia in hospitalized children at 7 sites. We identified relevant risk factors by literature review and iterative expert consultation. Decisions for inclusion in PERCH were based on comparability to published data, analytic plans, data collection costs and logistic feasibility, including interviewer time and subject fatigue. We aimed to standardize questions at all sites, but significant variation in the economic, cultural, and geographic characteristics of sites made it difficult to obtain this objective. Despite these challenges, the depth of the evaluation of multiple risk factors across the breadth of the PERCH sites should furnish new and valuable information about the major risk factors for childhood severe and very severe pneumonia, including risk factors for pneumonia caused by specific etiologies, in developing countries.
[show abstract][hide abstract] ABSTRACT: In most settings, sputum is not routinely collected for microbiological diagnosis from children with lower respiratory disease. To evaluate whether it is feasible and diagnostically useful to collect sputum in the Pneumonia Etiology Research for Child Health (PERCH) study, we reviewed the literature on induced sputum procedures. Protocols for induced sputum in children were collated from published reports and experts on respiratory disease and reviewed by an external advisory group for recommendation in the PERCH study. The advisory group compared 6 protocols: 4 followed a nebulization technique using hypertonic saline, and 2 followed a chest or abdomen massage technique. Grading systems for specimen quality were evaluated. Collecting sputum from children with lower respiratory tract illness is feasible and is performed around the world. An external advisory group recommended that sputum be collected from children hospitalized with severe and very severe pneumonia who participate in the PERCH study provided no contraindications exist. PERCH selected the nebulization technique using hypertonic saline.
[show abstract][hide abstract] ABSTRACT: The Pneumonia Etiology Research for Child Health (PERCH) project is a 7-country, standardized, comprehensive evaluation of the etiologic agents causing severe pneumonia in children from developing countries. During previous etiology studies, between one-quarter and one-third of patients failed to yield an obvious etiology; PERCH will employ and evaluate previously unavailable innovative, more sensitive diagnostic techniques. Innovative and rigorous epidemiologic and analytic methods will be used to establish the causal association between presence of potential pathogens and pneumonia. By strategic selection of study sites that are broadly representative of regions with the greatest burden of childhood pneumonia, PERCH aims to provide data that reflect the epidemiologic situation in developing countries in 2015, using pneumococcal and Haemophilus influenzae type b vaccines. PERCH will also address differences in host, environmental, and/or geographic factors that might determine pneumonia etiology and, by preserving specimens, will generate a resource for future research and pathogen discovery.
[show abstract][hide abstract] ABSTRACT: Diagnosing the etiologic agent of pneumonia has an essential role in ensuring the most appropriate and effective therapy for individual patients and is critical to guiding the development of treatment and prevention strategies. However, establishing the etiology of pneumonia remains challenging because of the relative inaccessibility of the infected tissue and the difficulty in obtaining samples without contamination by upper respiratory tract secretions. Here, we review the published and unpublished literature on various specimens available for the diagnosis of pediatric pneumonia. We discuss the advantages and limitations of each specimen, and discuss the rationale for the specimens to be collected for the Pneumonia Etiology Research for Child Health study.
[show abstract][hide abstract] ABSTRACT: Laboratory diagnostics are a core component of any pneumonia etiology study. Recent advances in diagnostic technology have introduced newer methods that have greatly improved the ability to identify respiratory pathogens. However, determining the microbial etiology of pneumonia remains a challenge, especially in children. This is largely because of the inconsistent use of assays between studies, difficulties in specimen collection, and problems in interpreting the presence of pathogens as being causally related to the pneumonia event. The laboratory testing strategy for the Pneumonia Etiology Research for Child Health (PERCH) study aims to incorporate a broad range of diagnostic testing that will be standardized across the 7 participating sites. We describe the current status of laboratory diagnostics for pneumonia and the PERCH approach for specimen testing. Pneumonia diagnostics are evolving, and it is also a priority of PERCH to collect and archive specimens for future testing by promising diagnostic methods that are currently under development.