Isolation of Coxiella burnetii from serum of patients with acute Q fever

• Published in: Journal of microbiological methods 2015-12, Vol.119, p.74-78
• Main Authors: Vincent, Gemma A., Graves, Stephen R., Robson, Jennifer M., Nguyen, Chelsea, Hussain-Yusuf, Hazizul, Islam, Aminul, Fenwick, Stanley G., Stenos, John
• Format: Article
• Language: English
• Subjects: Animals; Cell culture; Cercopithecus aethiops; Coxiella burnetii; Coxiella burnetii - genetics; Coxiella burnetii - growth & development; Coxiella burnetii - isolation & purification; Humans; Isolation; Q fever; Q Fever - blood; Q Fever - diagnosis; Q Fever - microbiology; Retrospective Studies; Serum - microbiology; Vero Cells
• ISSN: 0167-7012; 1872-8359
• DOI: 10.1016/j.mimet.2015.10.008

Worldwide there are few isolate collections of the intracellular bacterium Coxiella burnetii, due to the difficulties associated with working with the organism and the scarcity of suitable samples from which to attempt isolation. Particularly lacking are isolates from acute Q fever patients. The aim of this study was to evaluate whether the serum samples taken from patients with confirmed acute Q fever during the early stage of their disease represented a potential source of viable C. burnetii. Isolation was attempted from 65 of these samples by inoculation of the serum into Vero cell culture and was successful in 36 cases (55%). This high success rate was likely due to extended incubation of up to twelve weeks of the inoculated cultures, allowing the growth of the organism to levels detectable by PCR. Retrospective analysis of the time the sera was stored prior to inoculation into culture demonstrated that C. burnetii remained viable for 224days in samples stored refrigerated and 371days in samples stored frozen at −20°C. These results demonstrate that standard serum samples taken from acute Q fever patients are a valuable source of new isolates of C. burnetii, with no special handling of the specimens required to maintain the organism's viability. •Viable C. burnetii was successfully isolated from diagnostic serum samples.•Isolation success rate was 81% from PCR-positive specimens.•Isolation success was increased by extended incubation of isolation cultures.•Long term viability of C. burnetii in serum (>200days) was demonstrated.