A descriptive study of 42 cases of Branhamella catarrhalis pneumonia

PURPOSE: We studied the clinical and laboratory findings of patients with pneumonia due to Moraxella (Branhamella) catarrhalis to better characterize the types of patients who develop this pneumonia, the clinical features of the illness, and the type of and response to drug therapy, as well as the immediate and long-term survival of these patients. PATIENTS AND METHODS: Patients with sputum samples that met cellular criteria as quality samples and that grew B. catarrhalis as the sole pathogen were identified retrospectively from microbiology records at a regional referral hospital for cardiac and pulmonary diseases. Records of these patients were reviewed to identify patients with radiographic findings of pneumonia. Clinical and laboratory characteristics of these patients were then studied in detail. RESULTS: Forty-two patients who met the criteria for B. catarrhalis pneumonia were identified. Most patients were elderly (over 65 years; 55 percent), malnourished (69 percent), and had severe chronic obstructive pulmonary disease or another serious underlying disease (98 percent). The seasonal incidence of this pneumonia was October through April (88 percent), with the annual number of cases having increased since 1982. The clinical presentation was typically mild. Interstitial or mixed interstitial-alveolar infiltrates superimposed on pre-existing chronic lung disease was the most common radiographic finding. Approximately 90 percent of sputa were acceptable for Gram stain and contained 10 to more than 50 gram-negative cocci/1,000 x field. All cultures produced a heavy growth of B. catarrhalis, with 67 percent of strains positive for beta-lactamase. No patient had identified bacteremia (zero of 25 tested). Therapy with numerous agents including cefotaxime, amoxicillin/clavulanic acid, and trimethoprim/sulfamethoxazole resulted in a good clinical and bacteriologic response. However, 45 percent of patients died of their underling diseases on this admission or within three months. CONCLUSION: These findings provide a good profile of B. catarrhalis pneumonia. Despite the mild character of the illness, the pneumonia occurs in patients with end-stage pulmonary or malignant disease and almost 50 percent of patients die of their underlying diseases within three months.
Branhamella catarrhalis is a bacterial pathogen that can cause sinus and middle ear infections in children, and is also involved in chronic lower respiratory tract infections in adults. However, the role of B. catarrhalis in adult pneumonia has not been clearly defined. To establish a more complete profile of the manifestations of this pathogen in pneumonia, 42 cases of B. catarrhalis pneumonia in adults were examined. The bacteria were isolated from sputum samples of the subjects and pneumonia was confirmed by X-rays. Fifty-five percent of the subjects were over 65 years old and most (69 percent) were malnourished. Almost all of the subjects (98 percent) had underlying respiratory disease. In general, the pneumonia symptoms in these patients were not severe and included chills, malaise, chest pain, and fever. Fever was noted in only 57 percent of the subjects. Although symptoms were not severe, the prognosis was not good. Nine patients died during hospitalization and B. catarrhalis infection was considered to be the major factor in the death of three patients. Three months after discharge, 10 more subjects died of an underlying disease. It is suggested that B. catarrhalis pneumonia has been underreported because the bacteria have been difficult to isolate. B. catarrhalis infection is probably more common than previously thought and the number of cases is increasing. Significant findings included a high mortality and rate of malnutrition associated with this infection, and elderly patients are especially vulnerable. (Consumer Summary produced by Reliance Medical Information, Inc.)