Are third-generation cephalosporins unavoidable for empirical therapy of community-acquired pneumonia in adult patients who require ICU admission? A retrospective study

Background: Third-generation cephalosporins (3GCs) are recommended for empirical antibiotic therapy of community-acquired pneumonia (CAP) in patients requiring ICU admission. However, their extensive use could promote the emergence of extended-spectrum beta-lactamases-producing Enterobacteriaceae. Our aim was to assess whether the use of 3GCs in patients with CAP requiring ICU admission was justified.

Methods: We assessed all patients with CAP who required ICU admission during a 7-year period. We recorded empirical and definitive antibiotic therapies and susceptibility of causative pathogens. Amoxicillin, amoxicillin/clavulanate (A/C) susceptibilities as well as amikacin susceptibility of A/C-resistant strains were recorded.

Results: From January 2007 to March 2014, 391 patients were included in the study. Empirical 3GCs were used in 215 patients (55%). Among 267 patients with microbiologically documented CAP (68%), 241 received a beta-lactam as definitive therapy, and of those, 3CGs were chosen for 43 patients (18%). Amoxicillin or A/C was active against isolated pathogens in 159 patients (66%), while 39 patients (16%) required a beta-lactam with a broader spectrum than 3GCs. Ninety-four per cent of A/C-resistant strains were amikacin susceptible.

Conclusions: In ICU patients with CAP, 3GCs given on an empirical basis are changed, according to microbiological documentation, for another beta-lactam in 82% of cases especially to A/C in the absence of resistance risk factor. In patients evidencing risk factors for A/C-resistant strains infection, 3GCs or antipseudomonal beta-lactams including carbapenem associated with amikacin in the most severe patients seem a relevant empirical antibiotic therapy. This strategy could decrease 3GCs' use.