劇症肺炎患者2症例から分離した<I>Legionella dumoffii</I>および<I>Legionella pneumophila serogroup</I> 5について

Abstract

We encountered two cases of legionella pneumonia which ran a dramatic course and isolated Legionella dumoffii from one patient and Legionella pneumophila serogroup 5 from the other patient. The patient from whom L. dumoffii was isolated was a 59-year-old male with no basic disease. He presented chill, fever, coughing and other symptoms, starting on July 3, 1986, his disease was diagnosed as pneumonia at the clinic of his company. The patient was then introduced and admitted to our hospital. On admission chest radiography disclosed zonal pneumonia with an unclear border in the right superior lobe of the lung; a beta-lactam preparation was administered, but no effect was obtained and the lung lesion showed a rapid advance. From this condition, we suspected legionella pneumonia and changed the therapy to treatment with erythromycin and rifampicillin. Despite this, no improvement occurred and the patient died on the 26th hospital day. Colonies like Legionella colonies were separated from a total of seven specimens of biopsy aspirated matter from the airway and autopsy collected lung abscess and tracheal secretions, and the bacterium was identified L. dumoffii based on the biochemical and serological properties. In addition, the patient's serum was found to have an increased antibody titer against L. dumoffii. Based on these findings, the patient's disease was diagnosed as pneumonia as caused by L. dumoffii, a relatively rare bacterium as a member of the genus Legionella. The patient from whom Legionella pneumophila serogroup 5 was isolated was an 81-year-old man with basic diseases such as heart failure, anemia and hypothyroidism. He presented fever, general fatigue, anorexia and other symptoms, starting around June 2, 1987; pneumonia was suspected and the patient was urgently admitted to our hospital. The patient died of pneumonia of unknown cause on the second hospital day. To clarify the cause, autopsy was conducted; a large number of colonies like Legionella colonies were noted in the lung tissue. Identification test was then conducted and the bacterium was identified as L. pneumophila; we concluded that the patient's pneumonia had been caused by the identified bacterium L. pneumophila. The isolate was further subjected to slide agglutination test and identified as L. pneumophila serogroup 5.