Etiology of community-acquired pneumonia in hospitalized children based on WHO clinical guidelines

Community-acquired pneumonia (CAP) is a major cause of death in developing countries and of morbidity in developed countries. The objective of the study was to define the causative agents among children hospitalized for CAP defined by WHO guidelines and to correlate etiology with clinical severity and surrogate markers. Investigations included an extensive etiological workup. A potential causative agent was detected in 86% of the 99 enrolled patients, with evidence of bacterial (53%), viral (67%), and mixed (33%) infections. Streptococcus pneumoniae was accounted for in 46% of CAP. Dehydration was the only clinical sign associated with bacterial pneumonia. CRP and PCT were significantly higher in bacterial infections. Increasing the number of diagnostic tests identifies potential causes of CAP in up to 86% of children, indicating a high prevalence of viruses and frequent co-infections. The high proportion of pneumococcal infections re-emphasizes the importance of pneumococcal immunizatio

Detection et quantification des acides nucleiques en infectiologie: utilite, certitudes et limites

The amplification of nucleic acids is often used for the diagnosis and the follow-up of infectious diseases. The interpretation of PCR results varies according to the pathogens detected, the site of infection and the clinical presentation. PCR tests might be the reference method or only an help for the diagnosis. With the development of antiviral treatments quantitative PCR tests are now essential for the evaluation of treatment efficacy. A discussion with the laboratory is important for the correct interpretation of PCR results

Nouveaux tests pour le diagnostic de la tuberculose

Over the last decade, molecular biology techniques for identifying mycobacteria in pulmonary secretions have become more and more sensitive and rapid, even in smear negative samples. Nuclear amplification techniques also allow the rapid detection of resistance to first or second line anti-tuberculous drugs. The sensitivity of these techniques for non respiratory samples is yet to be determined. The diagnosis of latent tuberculous infection (LTBI) has also increased in sensitivity, specificity and positive predictive value through the use of interferon-γ release assays (IGRAs), which are tending to replace the tuberculin skin test, except for children aged under five. These tests, however, do have limitations which are important for the clinician; especially their inability to distinguish active from latent tuberculosis and their inability, in most circumstances, to exclude a diagnosis of active TB

Sensitivity, specificity and likelihood ratios of PCR in the diagnosis of syphilis: a systematic review and meta-analysis

To systematically review and estimate pooled sensitivity and specificity of the polymerase chain reaction (PCR) technique compared to recommended reference tests in the diagnosis of suspected syphilis at various stages and in various biological materials

Tuberculosis cluster in an immigrant community: case identification issues and a transcultural perspective

OBJECTIVES: In a low incidence area for tuberculosis (TB), a computerized database identified an unusually high proportion of patients coming from one single country between 2004 and 2006. To determine whether they constituted a cluster, whether clustering was due to recent transmission, and to understand what undermined the efficacy of the contact tracing procedure, we conducted a retrospective study of all patients with TB from this country. METHODS: Mycobacterium tuberculosis isolates of 15 TB cases originating from the same country over a 2(1/2) year period were analysed by restriction fragment length polymorphism (RFLP) and/or Rep-PCR. To identify links between patients, we revisited the social worker's files, cross-matched contacts' databases, and performed internet searches. A cultural evaluation was conducted by an anthropologist and an expert physician, through patient and community key informant interviews and a literature review. RESULTS: Genotyping confirmed that 11 of 15 patients had identical isolates. Additional data revealed an unsuspected complex network of social links between 9 of these 11 patients. The transcultural evaluation pointed out the major obstacles to efficient contact tracing, such as importance of social stigma related to TB, differences in communication style and health beliefs, and linguistic barriers. CONCLUSION: The combined finding of identical genotypes and important social links between patients confirmed the suspicion of a TB cluster due to recent transmission. The cultural evaluation helped to explain the difficulties encountered during the contact tracing procedure, and offered strategies to improve its efficacy despite the magnitude of the social stigma attached to TB in this community

Comparison of Diagnostic Accuracy of PCR Targeting the 47-Kilodalton Protein Membrane Gene of Treponema pallidum and PCR Targeting the DNA Polymerase I Gene: Systematic Review and Meta-analysis

Treponema pallidum PCR (Tp-PCR) testing now is recommended as a valid tool for the diagnosis of primary or secondary syphilis. The objectives were to systematically review and determine the optimal specific target gene to be used for Tp-PCR. Comparisons of the performance of the two main targets are tpp47 and polA genes were done using meta-analysis. Three electronic bibliographic databases, representing abstract books from five conferences specialized in infectious diseases from January 1990 to March 2015, were searched. Search keywords included ("syphilis" OR "Treponema pallidum" OR "neurosyphilis") AND ("PCR" OR "PCR" OR "molecular amplification"). We included diagnostic studies assessing the performance of Tp-PCR targeting tpp47 (tpp47-Tp-PCR) or the polA gene (polA-Tp-PCR) in ulcers from early syphilis. All studies were assessed against quality criteria using the QUADAS-2 tool. Of 37 studies identified, 62.2% were judged at low risk of bias or applicability. Most used the U.S. Centers for Disease Control and Prevention (CDC) case definitions for primary or secondary (early) syphilis (89.2%; n = 33); 15 (40.5%) used darkfield microscopy (DFM). We did not find differences in sensitivity and specificity between the two Tp-PCR methods in the subgroup of studies using adequate reference tests. Among studies using DFM as the reference test, sensitivities were 79.8% (95% confidence intervals [CI], 72.7 to 85.4%) and 71.4% (46.0 to 88.0%) for tpp47-Tp-PCR and polA-Tp-PCR (P = 0.217), respectively; respective specificities were 95.3% (93.5 to 96.6%) and 93.7% (91.8 to 95.2%) (P = 0.304). Our findings suggest that the two Tp-PCR methods have similar accuracy and could be used interchangeably

Detection of mycobacterial nucleic acids by polymerase chain reaction in fixed tissue specimens of patients with human immunodeficiency virus infection. Swiss HIV Cohort Study

A polymerase chain reaction (PCR) method, which amplifies a fragment of the 16S ribosomal RNA (rRNA) gene present in all mycobacterial species, was developed and tested on 84 formalin-fixed paraffin-embedded tissue specimens from 51 patients with human immunodeficiency (HIV) infection. The PCR products were characterized either by sequencing or by hybridization with nonradioactive oligonucleotide probes specific for Mycobacterium tuberculosis complex, M. avium, or M. genavense. Sequencing was successful for 26 samples compared with the 45 samples for probe hybridization. The sensitivity of DNA amplification compared with microscopic examination was 79.5%. A mixed infection was detected with M. genavense for only one patient who was infected with M. tuberculosis complex. In the group of 22 control patients, where no diagnosis of mycobacterial infection was made during life and no acid-fast bacteria were seen during the autopsy, four samples of one patient were positive by hybridization with the M. tuberculosis probe. This patient had a clinical history compatible with tuberculosis. This PCR method may be a powerful tool for the precise diagnosis of mycobacterial infections from histopathologic material, provided that several sections from the same specimen block are tested