A mobile biosafety microanalysis system for infectious agents.

Biological threats posed by pathogens such as Ebola virus must be quickly diagnosed, while protecting the safety of personnel. Scanning electron microscopy and microanalysis requires minimal specimen preparation and can help to identify hazardous agents or substances. Here we report a compact biosafety system for rapid imaging and elemental analysis of specimens, including powders, viruses and bacteria, which is easily transportable to the site of an incident.

A filtration based technique for simultaneous SEM and TEM sample preparation for the rapid detection of pathogens.

Diagnostic electron microscopy for infectious diseases has the advantage that "everything" in the specimen can be observed, without a priori knowledge of the likely identity of the microorganisms present in the sample. The classical specimen preparation method used employs a droplet of sample, which allows particles to adsorb to a support film, and is subsequently negative stained. This "grid on drop" procedure has a sensitivity range of approximately 106 viruses per mL if no enrichment procedures are used. In the current investigation we present a novel use of filtration that allows us to detect viruses at concentrations as low as 102 viruses per mL. We present here methods based on filtration, in which total virus, and not virus concentration, is the limiting factor for detection. We show that filtration is more sensitive than conventional negative staining and can detect as few as 5 × 103 particles per sample.

Application of "omics" to prion biomarker discovery.

The advent of genomics and proteomics has been a catalyst for the discovery of biomarkers able to discriminate biological processes such as the pathogenesis of complex diseases. Prompt detection of prion diseases is particularly desirable given their transmissibility, which is responsible for a number of human health risks stemming from exogenous sources of prion protein. Diagnosis relies on the ability to detect the biomarker PrP(Sc), a pathological isoform of the host protein PrP(C), which is an essential component of the infectious prion. Immunochemical detection of PrP(Sc) is specific and sensitive enough for antemortem testing of brain tissue, however, this is not the case in accessible biological fluids or for the detection of recently identified novel prions with unique biochemical properties. A complementary approach to the detection of PrP(Sc) itself is to identify alternative, "surrogate" gene or protein biomarkers indicative of disease. Biomarkers are also useful to track the progress of disease, especially important in the assessment of therapies, or to identify individuals "at risk". In this review we provide perspective on current progress and pitfalls in the use of "omics" technologies to screen body fluids and tissues for biomarker discovery in prion diseases.

Are fluoroquinolone-susceptible isolates of Streptococcus pneumoniae really susceptible? A comparison of resistance mechanisms in Canadian isolates from 1997 and 2003.

OBJECTIVES: To assess the prevalence of efflux and amino acid substitutions in ParC and GyrA in Canadian clinical isolates of fluoroquinolone-susceptible Streptococcus pneumoniae with levofloxacin MICs of 1 mg/L collected before the introduction of the respiratory fluoroquinolones (1995-1997) and after 7 years of use (2003). METHODS: Quinolone resistance determining regions of parC and gyrA were sequenced for 111 clinical isolates collected from 1995 to 1997 and 665 isolates collected in 2003. Efflux was assessed using a reserpine agar dilution method. RESULTS: No isolates exhibited efflux. No significant increase in isolates harbouring amino acid substitutions was observed over time (0.9% in 1995-1997 to 2.1% in 2003, P = 0.32). However, the proportion of isolates with a ciprofloxacin MIC = 2 mg/L and a levofloxacin MIC = 1 mg/L versus ciprofloxacin MIC = 1 mg/L and a levofloxacin MIC = 1 mg/L increased over time (3.6% to 6.5%, P = 0.0021). CONCLUSIONS: No increase in prevalence of first-step parC mutations was observed among all fluoroquinolone-susceptible clinical isolates of S. pneumoniae with levofloxacin MICs of 1 mg/L after the introduction of the respiratory fluoroquinolones; however, fluoroquinolones appear to be selecting for isolates with elevated ciprofloxacin MICs.