title: Detecting and measuring small numbers of viable Coxiella burnetii.
abstract: Coxiella burnetii is an acidophilic, intracellular bacterium that causes the human disease Q fever. In some studies, it is important to distinguish between viable and nonviable C. burnetii. We compared four methods for detecting and measuring viable C. burnetii in biological samples as follows: growth in two different cell culture lines, infection of severe combined immunodeficient (SCID) mice (leading to death) and infection of SCID mice with detection of C. burnetii in their spleen (after euthanasia at day 50 postinfection). Two isolates of C. burnetii were used ('Henzerling' and 'Arandale'). Our in-house qPCR assay for C. burnetii DNA was used as a control. SCID mouse inoculation was more sensitive than cell culture. The assay that detected C. burnetii in SCID mouse spleens was slightly more sensitive than SCID mice deaths alone. Approximately one viable C. burnetii cell could be detected by this method, making it suitable for determining the viability of C. burnetii in a sample.
authors.affiliation: Australian Rickettsial Reference Laboratory, Geelong, Australia.
authors.forename: Michelle
authors.initials: M
authors.lastname: Lockhart
authors.forename: Aminul
authors.initials: A
authors.lastname: Islam
authors.forename: Stephen
authors.initials: S
authors.lastname: Graves
authors.forename: Stan
authors.initials: S
authors.lastname: Fenwick
authors.forename: John
authors.initials: J
authors.lastname: Stenos
mesh_terms: D000818:Animals; D001431:Bacteriological Techniques / Q000379:methods*; D002460:Cell Line; D016997:Coxiella burnetii / Q000254:growth & development / Q000302:isolation & purification* / Q000472:pathogenicity; D005260:Female; D006801:Humans; D051379:Mice; D016513:Mice, SCID; D050296:Microbial Viability; D012680:Sensitivity and Specificity; D013154:Spleen / Q000382:microbiology; D016019:Survival Analysis