Cost-effectiveness analysis of antiviral treatment in the management of seasonal influenza A: point-of-care rapid test versus clinical judgment.

BACKGROUND: A point-of-care rapid test (POCRT) may help early and targeted use of antiviral drugs for the management of influenza A infection. OBJECTIVE: (i) To determine whether antiviral treatment based on a POCRT for influenza A is cost-effective and, (ii) to determine the thresholds of key test parameters (sensitivity, specificity and cost) at which a POCRT based-strategy appears to be cost effective. METHODS: An hybrid « susceptible, infected, recovered (SIR) ¼ compartmental transmission and Markov decision analytic model was used to simulate the cost-effectiveness of antiviral treatment based on a POCRT for influenza A in the social perspective. Data input parameters used were retrieved from peer-review published studies and government databases. The outcome considered was the incremental cost per life-year saved for one seasonal influenza season. RESULTS: In the base-case analysis, the antiviral treatment based on POCRT saves 2 lives/100,000 person-years and costs $7600 less than the empirical antiviral treatment based on clinical judgment alone, which demonstrates that the POCRT-based strategy is dominant. In one and two way-sensitivity analyses, results were sensitive to the POCRT accuracy and cost, to the vaccination coverage as well as to the prevalence of influenza A. In probabilistic sensitivity analyses, the POCRT strategy is cost-effective in 66% of cases, for a commonly accepted threshold of $50,000 per life-year saved. CONCLUSION: The influenza antiviral treatment based on POCRT could be cost-effective in specific conditions of performance, price and disease prevalence.

Impact of DNA sequence and oligonucleotide length on a polythiophene-based fluorescent DNA biosensor.

DNA hybridization is a universal and specific mechanism for the recognition of biological targets. Some cationic polythiophene transducers sensitive to DNA structure have been previously utilized to detect such biomolecules. Further characterization of these systems indicates that both DNA sequence composition and length modulate the biosensor performance. It appears that different repeated sequence patterns cause different conformational changes of the polythiophene, from a more relaxed form to an extremely rigid one. A length difference between the DNA oligonucleotide probe and target has a detrimental effect on the fluorescent signal, but it can be attenuated by changing the sequence composition of the protruding target sequence. This demonstrates that the nature of DNA can be critical for hybridization-based detection systems.

Rapid filtration separation-based sample preparation method for Bacillus spores in powdery and environmental matrices.

Authorities frequently need to analyze suspicious powders and other samples for biothreat agents in order to assess environmental safety. Numerous nucleic acid detection technologies have been developed to detect and identify biowarfare agents in a timely fashion. The extraction of microbial nucleic acids from a wide variety of powdery and environmental samples to obtain a quality level adequate for these technologies still remains a technical challenge. We aimed to develop a rapid and versatile method of separating bacteria from these samples and then extracting their microbial DNA. Bacillus atrophaeus subsp. globigii was used as a simulant of Bacillus anthracis. We studied the effects of a broad variety of powdery and environmental samples on PCR detection and the steps required to alleviate their interference. With a benchmark DNA extraction procedure, 17 of the 23 samples investigated interfered with bacterial lysis and/or PCR-based detection. Therefore, we developed the dual-filter method for applied recovery of microbial particles from environmental and powdery samples (DARE). The DARE procedure allows the separation of bacteria from contaminating matrices that interfere with PCR detection. This procedure required only 2 min, while the DNA extraction process lasted 7 min, for a total of <10 min. This sample preparation procedure allowed the recovery of cleaned bacterial spores and relieved detection interference caused by a wide variety of samples. Our procedure was easily completed in a laboratory facility and is amenable to field application and automation.

The development of a silica nanoparticle-based label-free DNA biosensor.

A silica nanoparticle-based DNA biosensor capable of detecting Bacillus anthracis bacteria through the use of unlabelled ss-oligonucleotides has been developed. The biosensor makes use of the optical changes that accompany a nanoparticle-immobilized cationic conjugated polymer (polythiophene) interacting with single-stranded vs. hybridized oligonucleotides, where a fluorescence signal appears only when hybridized DNA is present (i.e. only when the ss-oligonucleotide interacting with the polymer has hybridized with its complement). In order to enhance the sensitivity of the biosensor, two different nanoparticle architectures were developed and used to elucidate how the presence of neighboring fluorophores on the nanoparticle surface affects Förster-resonant energy transfer (FRET) between the polythiophene/oligonucleotide complex (FRET donor) and the fluorophores (FRET acceptors). We demonstrate that the silica nanoparticle-based FRET platform lowers the limit of detection at least 10-fold in comparison to the polythiophene itself, and allows the detection of ∼2 × 10(-12) moles of ss-oligonucleotide in a 100 µL sample with a standard fluorimeter (i.e. has a limit of detection of ∼2 nM ssDNA). Such nanoparticle-based biosensor platforms are beneficial because of the robustness and stability inherent to their covalent assembly and they provide a valuable new tool that may allow for the sensitive, label-free detection (the target DNA that produces the fluorescence signal is unlabelled) without the use of polymerase chain reaction.

Physical mapping of 32 genetic markers on the Pseudomonas aeruginosa PAO1 chromosome.

The Pseudomonas aeruginosa chromosome was fractionated with the enzymes SpeI and DpnI, and genomic fragments were separated by PFGE and used for mapping a collection of 40 genes. This permitted the localization of 8 genes previously mapped and of 32 genes which had not been mapped. We showed that a careful search of databases and identification of sequences that were homologous to known genes could be used to design and synthesize DNA probes for the mapping of P. aeruginosa homologues by Southern hybridization with genomic fragments, resulting in definition of the locations of the aro-2, dapB, envA, mexA, groEL, oprH, oprM, oprP, ponA, rpoB and rpoH genetic markers. In addition, a combination of distinct DNA sources were utilized as radioactively labelled probes, including specific restriction fragments of the cloned genes (glpD, opdE, oprH, oprO, oprP, phoS), DNA fragments prepared by PCR, and single-stranded DNA prepared from phagemid libraries that had been randomly sequenced. We used a PCR approach to clone fragments of the putative yhhF, sucC, sucD, cypH, pbpB, murE, pbpC, soxR, ftsA, ftsZ and envA genes. Random sequencing of P. aeruginosa DNA from phagemid libraries and database searching permitted the cloning of sequences from the acoA, catR, hemD, pheS, proS, oprD, pyo and rpsB gene homologues. The described genomic methods permit the rapid mapping of the P. aeruginosa genome without linkage analysis.