Clinical Manilcstations of Legionnaires' Disease and Recommended Therapy 



define a microbial etiology were unsuccesst'ul. The patient's condition improved greatly, and 

 he was discharged on the 1 5th hospital day with a diagnosis of pneumonia of undetermined 

 etiology, possibly caused by a virus or the LDB. From July 8 to July 18 his antibody titer to 

 the LDB (serogroup 1) by indirect immunonuorescence rose from 32 to 256. 



Case History #2. 



A 52-year-old British tourist experienced malaise and fever on September 15 while 

 vacationing in Spain. He returned to England on September 20. Three days later he develop- 

 ed cough, shortness of breath, and diarrhea. On admission to a hospital on September 24, he 

 was confused and had a temperature of 40°C and signs of right-sided pneumonia. His chest 

 radiograph showed infiltrates out of proportion to the clinical findings, and his leukocyte 

 count was nomial; he was therefore treated for primary atypical pneumonia with erythro- 

 mycin. His fever lysed within 3 days, but he remained confused, and a lumbar puncture and 

 an encephalogram were done because encephalitis was suspected. No abnormalities were 

 found, and by October 7 the patient was asymptomatic except for residual asthenia. Rou- 

 tine microbiological diagnostic tests were unrevealing. Indirect immunotluorescence was 

 used to document the patient's seroconversion to the LDB (serogroup 1 ) antigen. 



Legionnaires' disease may also take the form of a self-limited illness with fever, myalgia, 

 malaise, and headache, but with few or no respiratory manifestations and no pneumonia. This 

 syndrome, originally temied "Pontiac fever," is remarkable for the absence of associated fatal- 

 ities. The reason for the difference between the pneumonic and Pontiac fever syndromes of LD 

 remains conjectural. 



Symptomatic therapy suffices for patients with the Pontiac fever syndrome. Specific treat- 

 ment for pneumonia caused by the LDB is not based on controlled clinical trials of human illness, 

 but available evidence suggests the eiythromycin reduces the risk of fatality among patients with 

 pulmonic LD. Doses of up to 1 gram every 6 h of erythromycin gluceptate or lactobionate can be 

 given intravenously as the initial therapy for seriously ill patients. Note that the intravenous 

 formulations of erythromycin must be reconstituted in Sterile Water tor Injection without bacte- 

 riostatic preservatives. The dose can be lowered, and the medication can be given orally as the 

 patient's condition stabilizes. The optimal duration of treatment remains unclear; some clinicians 

 experienced in treating patients with LD continue antibiotic therapy for 3 wk or longer, but this 

 is not a universal practice. The dosage of erythromycin must be adjusted for patients with severe 

 hepatic disease or renal failure. An alternative to erythromycin is a tetracycline. Rifampin is also 

 effective against the LDB in several laboratory models, but it should only be prescribed for LD 

 patients as a supplement to erythromycin if the patients have not responded well to a single 

 antibiotic. It could also be used in conducting properly organized trials to compare erythromycin 

 therapy with erythromycin-rifampin therapy. Treatment with penicillins, cephalosporins, or 

 aminoglycosides does not appear to benefit patients with LD. 



Supportive therapy is as important as antibiotic treatment for patients with LD. Those with 

 pneumonia should have their arterial blood gases monitored, and oxygen therapy and assisted 

 ventilation should be provided as indicated. Attention to fluid and electrolyte balance is manda- 

 tory—particularly for patients with high fever, diarrhea, or disturbances of consciousness. Patients 

 who have hypotension or shock may need to have carefully monitored urine output, central 

 venous pressure, or pulmonary capillary wedge pressure, and intra-arterial blood pressure to 

 provide a guide for intravenous fluid administration and vasopressor therapy. Renal function 

 should be followed carefully during the acute illness; an occasional patient requires dialysis until 

 renal function is restored. Stuporous and comatose patients require special nursing care to pre- 

 vent conjunctival desiccation, parotitis, aspiration of gastric contents, urinary retention, fecal 

 impaction, and pressure sores. 



