[A case of Q fever infection causing acute exacerbation of chronic respiratory failure].

The authors report a case of Q fever infection that caused acute exacerbation of chronic respiratory failure, which had developed as a sequela of pulmonary tuberculosis. This case was found on wide-ranging serological screening for respiratory infection performed in order to investigate the prevalence of Q fever in Japan. A 73-year-old man who had been treated for hypertension and sequelae of pulmonary tuberculosis was admitted to our hospital because of fever, productive cough, and dyspnea on effort. Hypoxia and right heart failure were detected on arterial blood analysis and ultrasonography. The acute exacerbation was triggered by respiratory infection and although the infection improved on azithromycin treatment after admission, respiratory failure continued for the period of admission. Home oxygen therapy was required for the management of chronic respiratory failure on discharge. Paired serum samples were tested for antibodies against Coxiella burnetii by indirect immunofluorescence, showing an elevated antibody titer in the convalescent phase. We believe that Q fever infection caused acute exacerbation of chronic respiratory failure, and that C. burnetii is an agent that might influence the clinical course of chronic respiratory failure.