Clinical characteristics of patients with community-acquired pneumoniae due to Moraxella catarrhalis: a retrospective single center study

Abstract

Background: Previous reports showed that Moraxella catarrhalis (M. catarrhalis) was one of the main pathogen of community-acquired pneumonia (CAP); however, recent mate-analysis revealed the frequency of CAP caused by M. catarrhalis in Japan was only 1.9% (58 of 3077 patients). In fact, only a few case reports describing CAP due to this pathogen have been published until now, and the data regarding clinical features of M. catarrhalis pneumonia is limited in our country. Methods & Materials: The primary objective of this retrospective study was to determine the clinical characteristics of patients with CAP due to M. catarrhalis. Patients aged over 20 who visited Okinawa Prefectural Miyako hospital located in Okinawa, Japan between August 2013 and August 2017 were enrolled. Patients with bed-ridden status, detection of other microorganisms from sputum, and absence of infiltration on chest x-ray were excluded. Results: During the study period, 70 CAP cases due to M. catarrhalis were identified. Most patients visited to the hospital in winter season, which accounted for 50%. Fifty-one percent of the patients were men and the median age was 78 years old (range; 21 to 98). Of these 70 patients, percentage of in-patients and never-smokers were 68.6% and 61.4%, respectively. According to the result of pneumonia severity scoring system, A-DROP, showed general status was mild in more than half of these patients (score < 2 was 67.2%). Most patients presented a fever and cough; however, chill developed in only 6 cases (8.5%). The most common respiratory underlying condition was COPD (28.5%; 22 of 70), and of these, acute exacerbations were occurred in 3 cases (15%). In radiological findings, bronchopneumonia pattern was predominant compared to lobar pneumonia pattern (84% vs 16%), and bilateral chest infiltration was observed in 22 cases (31.4%). The average hospitalized period was 8 days (range; 3-17). All patients but one recovered without recurrence. Conclusion: In the present study, the characteristics of CAP due to M. catarrhalis were as follows; (1) mainly occurred in elderly patients, (2) presented with relatively mild symptoms, (3) bronchopneumonia pattern with bilateral infiltration was predominant, and (4) prognosis was good.