Bacteraemic community-acquired pneumonia due to Gram-negative bacteria: incidence, clinical presentation and factors associated with severity during hospital stay

Many studies have evaluated the clinical characteristics of Gram-negative bacteria (GNB) pneumonia. However, in most cases the bacteriological diagnosis is based on unreliable respiratory samples, and research rarely focuses on only bacteraemic patients. The aim of this study was to describe the incidence, clinical characteristics, outcomes, and factors associated with severity during the hospital stay of patients diagnosed with bacteraemic community-acquired pneumonia (CAP) due to GNB. Patients consecutively admitted with bacteraemic CAP due to GNB were enrolled in the study, with exclusion of additional foci of infection. CAP due to GNB accounted for 1.2% of the total CAP cases admitted and 3.5% of those with a confirmed aetiological diagnosis. Fifty-one patients were studied (mean age: 73 +/- 11.3 years). Escherichia coli (30 cases; 58.8%) and Klebsiella pneumoniae (9 cases; 17.6%) were the most commonly isolated strains. The main symptoms were fever, cough, and dyspnoea. Eleven (21.6%) patients presented mental confusion, ten (19.6%) followed a severe clinical course, and six (11.8%) died. Absence of fever, radiologically multilobar involvement, and the prescription of an inadequate empirical antimicrobial therapy were independent factors associated with severity during the hospital stay. Bacteraemic CAP due to GNB is an uncommon entity. Among the patients studied, E. coli was the main GNB found. A total of 19.6% of patients followed a severe clinical course. The factors identified in this study may alert physicians to a group of patients at risk of suffering complications during their hospital stay.