Antimicrobial treatment failures in patients with community-acquired pneumonia - Causes and prognostic implications

The aim of the study was to determine the causes and prognostic implication s of antimicrobial treatment failures in patients with nonresponding and pr ogressive life-threatening, community-acquired pneumonia. Forty-nine patien ts hospitalized with a presumptive diagnosis of community-acquired pneumoni a during a 16-mo period, failure to respond to antimicrobial treatment, and documented repeated microbial investigation greater than or equal to 72 h after initiation of in-hospital antimicrobial treatment were recorded. A de finite etiology of treatment failure could be established in 32 of 49 (65%) patients, and nine additional patients (18%) had a probable etiology. Trea tment failures were mainly infectious in origin and included primary, persi stent, and nosocomial infections (n = 10 [19%], 13 [24%], and 11 [20%] of c auses, respectively). Definite but not probable persistent infections were mostly due to microbial resistance to the administered initial empiric anti microbial treatment. Nosocomial infections were particularly frequent in pa tients with progressive pneumonia. Definite persistent infections and nosoc omial infections had the highest associated mortality rates (75 and 88%, re spectively). Nosocomial pneumonia was the only cause of treatment failure i ndependently associated with death in multivariate analysis (RR, 16.7; 95% CI, 1.4 to 194.9; p = 0.03). We conclude that the detection of microbial re sistance and the diagnosis of nosocomial pneumonia are the two major challe nges in hospitalized patients with community-acquired pneumonia who do not respond to initial antimicrobial treatment. In order to establish these pot entially life-threatening etiologies, a regular microbial reinvestigation s eems mandatory for all patients presenting with antimicrobial treatment fai lures.