FluorescenceIn SituHybridization (FISH) and Peptide Nucleic Acid Probe-Based FISH for Diagnosis of Q Fever Endocarditis and Vascular Infections

ABSTRACTEndocarditis and vascular infections are common manifestations of persistent localized infection due toCoxiella burnetii, and recently, fluorescencein situhybridization (FISH) was proposed as an alternative tool for their diagnosis. In this study, we evaluated the efficiency of FISH in a series of valve and vascular samples infected byC. burnetii. We tested 23C. burnetii-positive valves and thrombus samples obtained from patients with Q fever endocarditis. Seven aneurysms and thrombus specimens were retrieved from patients with Q fever vascular infections. Samples were analyzed by culture, immunochemistry, and FISH with oligonucleotide and PNA probes targetingC. burnetii-specific 16S rRNA sequences. The immunohistochemical analysis was positive for five (17%) samples with significantly more copies ofC. burnetiiDNA than the negative ones (P= 0.02). FISH was positive for 13 (43%) samples and presented 43% and 40% sensitivity compared to that for quantitative PCR (qPCR) and culture, respectively. PNA FISH detectedC. burnetiiin 18 (60%) samples and presented 60% and 55% sensitivity compared to that for qPCR and culture, respectively. Immunohistochemistry had 38% and 28% sensitivity compared to that for FISH and PNA FISH, respectively. Samples found positive by both immunohistochemistry and PNA FISH contained significantly more copies ofC. burnetiiDNA than the negative ones (P= 0.03). Finally, PNA FISH was more sensitive than FISH (60% versus 43%, respectively) for the detection ofC. burnetii. We provide evidence that PNA FISH and FISH are important assays for the diagnosis ofC. burnetiiendocarditis and vascular infections.

Identification of pathogenic bacteria in complex samples using a smartphone based fluorescence microscope

A smartphone-based fluorescence microscope for detection of bacteria in complex samples using a species-specific peptide nucleic acid probe.