Chapter: Microbiology and Immunology: Bacteriology: Rickettsia, Orientia Ehrlichia, and Coxiella

Laboratory Diagnosis - Coxiella burnetii Infections

C. burnetii can be diagnosed by isolation of the bacteria from clinical specimens in guinea pigs, mice, and developing chick embryo.

Laboratory Diagnosis

C. burnetii can be diagnosed by isolation of the bacteria from clinical specimens in guinea pigs, mice, and developing chick embryo. But isolation of the bacteria by these methods is not attempted, because these procedures are biohazardous and are also not required.

◗ Serodiagnosis

Serology is the mainstay of diagnosis of Q fever. Serological tests include immunofluorescence test, complement fixation test, and ELISA. All these tests detect IgM or IgG antibodies by using phase 1 and 2 antigens. Serodiagnosis of acute Q fever is made by demonstration of (a) IgG titer of 1:200 or more, or IgM titer of 1:50 or more in a single serum specimen, or (b) a fourfold rise of antibody titer between acute and convalescent sera. The IgG antibodies are present in serum for more than 1 year in 90% of patients, whereas IgM antibodies are present only for 2 weeks and become negative after 2 weeks.

Serodiagnosis of chronic Q fever is made by demon-stration of high antibody titer against phase 1 and 2 anti-gens. Antibodies against phase 1 antigen are always higher. Weil–Felix test is not used for diagnosis of Q fever.

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Microbiology and Immunology: Bacteriology: Rickettsia, Orientia Ehrlichia, and Coxiella : Laboratory Diagnosis - Coxiella burnetii Infections |