Comparison of Real-Time Quantitative PCR and Culture for the Diagnosis of Emerging Rickettsioses

Emmanouil Angelakis (1) , Hervé Richet (1) , Jean-Marc Rolain (1) , Bernard La Scola (1) , Didier Raoult (1)

1 URMITE - Unité de Recherche sur les Maladies Infectieuses et Tropicales Emergentes

Diagnosis of Rickettsia infection would benefit by use of the more rapid and sensitive method of quantitative real-time PCR than the time-intensive and less sensitive method of culturing Rickettsia species from skin biopsies. We evaluated culture sensitivity compared to PCR according to sampling delay and previous antibiotic treatment. We found that skin biopsies can be positive even when molecular tests were negative, and a negative result using molecular assays did not exclude the diagnosis of Rickettsia spp. infection. Rickettsia africae was the most common species in skin biopsies and R. slovaca was most common in ticks. We found a positive correlation between the number of bacteria copies and the isolation success in skin biopsies and ticks. The probability of isolating Rickettsia spp. was higher in untreated patients and in patients from our hometown. To increase the sensitivity of culture, skin biopsies should be sampled before treatment early in the course of the disease and should be inoculated as soon as possible.

Keywords: Rickettsia; Biopsy; Polymerase chain reaction; Antibiotics; Skin infections; Serology; Specimen preparation and treatment; Diagnostic medicine

Domains: Life Sciences [q-bio]; Human health and pathology; Infectious diseases

Emmanouil Angelakis, Hervé Richet, Jean-Marc Rolain, Bernard La Scola, Didier Raoult. Comparison of Real-Time Quantitative PCR and Culture for the Diagnosis of Emerging Rickettsioses. PLoS Neglected Tropical Diseases, 2012, 6 (3), ⟨10.1371/journal.pntd.0001540⟩. ⟨hal-01785695⟩