title: Comparison of two quantitative real time PCR assays for Rickettsia detection in patients from Tunisia.
abstract: OBJECTIVE
  Quantitative real time PCR (qPCR) offers rapid diagnosis of rickettsial infections. Thus, successful treatment could be initiated to avoid unfavorable outcome. Our aim was to compare two qPCR assays for Rickettsia detection and to evaluate their contribution in early diagnosis of rickettsial infection in Tunisian patients.
  
  
  METHODS
  Included patients were hospitalized in different hospitals in Tunisia from 2007 to 2012. Serology was performed by microimmunofluorescence assay using R. conorii and R. typhi antigens. Two duplex qPCRs, previously reported, were performed on collected skin biopsies and whole blood samples. The first duplex amplified all Rickettsia species (PanRick) and Rickettsia typhi DNA (Rtt). The second duplex detected spotted fever group Rickettsiae (RC00338) and typhus group Rickettsiae DNA (Rp278).
  
  
  RESULTS
  Diagnosis of rickettsiosis was confirmed in 82 cases (57.7%). Among 44 skin biopsies obtained from patients with confirmed diagnosis, the first duplex was positive in 24 samples (54.5%), with three patients positive by Rtt qPCR. Using the second duplex, positivity was noted in 21 samples (47.7%), with two patients positive by Rp278 qPCR. Among79 whole blood samples obtained from patients with confirmed diagnosis, panRick qPCR was positive in 5 cases (6.3%) among which two were positive by Rtt qPCR. Using the second set of qPCRs, positivity was noted in four cases (5%) with one sample positive by Rp278 qPCR. Positivity rates of the two duplex qPCRs were significantly higher among patients presenting with negative first serum than those with already detectable antibodies.
  
  
  CONCLUSIONS
  Using qPCR offers a rapid diagnosis. The PanRick qPCR showed a higher sensitivity. Our study showed that this qPCR could offer a prompt diagnosis at the early stage of the disease. However, its implementation in routine needs cost/effectiveness evaluation.
authors.affiliation: Laboratory of Microbiology, Research Laboratory "MPH", Habib Bourguiba University Hospital of Sfax, Sfax University, Sfax, Tunisia.
authors.forename: Abir
authors.initials: A
authors.lastname: Znazen
authors.affiliation: Laboratory of Microbiology, Research Laboratory "MPH", Habib Bourguiba University Hospital of Sfax, Sfax University, Sfax, Tunisia.
authors.forename: Hanen
authors.initials: H
authors.lastname: Sellami
authors.affiliation: Infectious diseases department, Hedi Chaker University Hospital of Sfax, Sfax University, Sfax, Tunisia.
authors.forename: Emna
authors.initials: E
authors.lastname: Elleuch
authors.affiliation: Infectious diseases department, Farhat Hached University Hospital of Sousse, Sousse, Tunisia.
authors.forename: Zouhour
authors.initials: Z
authors.lastname: Hattab
authors.affiliation: Medical department, Regional Hospital of Zarzis, Zarzis, Tunisia.
authors.forename: Laroussi
authors.initials: L
authors.lastname: Ben Sassi
authors.affiliation: Laboratory of entomology, Pasteur Institute of Tunis, Tunis, Tunisia.
authors.forename: Fatma
authors.initials: F
authors.lastname: Khrouf
authors.affiliation: Intensive care unit, Habib Bourguiba University Hospital of Sfax, Sfax University, Sfax, Tunisia.
authors.forename: Hassen
authors.initials: H
authors.lastname: Dammak
authors.affiliation: Infectious diseases department, Farhat Hached University Hospital of Sousse, Sousse, Tunisia.
authors.forename: Amel
authors.initials: A
authors.lastname: Letaief
authors.affiliation: Infectious diseases department, Hedi Chaker University Hospital of Sfax, Sfax University, Sfax, Tunisia.
authors.forename: Mounir
authors.initials: M
authors.lastname: Ben Jemaa
authors.affiliation: Laboratory of Microbiology, Research Laboratory "MPH", Habib Bourguiba University Hospital of Sfax, Sfax University, Sfax, Tunisia.
authors.forename: Adnene
authors.initials: A
authors.lastname: Hammami
mesh_terms: D000328:Adult; D000942:Antigens, Bacterial / Q000276:immunology*; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics*; D042241:Early Diagnosis; D005260:Female; D005455:Fluorescent Antibody Technique / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D060888:Real-Time Polymerase Chain Reaction / Q000379:methods; D012286:Rickettsia typhi / Q000235:genetics / Q000302:isolation & purification*; D014416:Tunisia; D014437:Typhus, Endemic Flea-Borne / Q000175:diagnosis* / Q000382:microbiology
chemical_list: D000942:Antigens, Bacterial; D004269:DNA, Bacterial