Antibiotic selection in the treatment of acute invasive infections by Pseudomonas aeruginosa: Guidelines by the Spanish Society of Chemotherapy

Abstract

Pseudomonas aeruginosa is characterized by a notable intrinsic resistance to antibiotics, mainly mediated by the expression of inducible chromosomic β-lactamases and the production of constitutive or inducible efflux pumps. Apart from this intrinsic resistance, P. aeruginosa possess an extraordinary ability to develop resistance to nearly all available antimicrobials through selection of mutations. The progressive increase in resistance rates in P. aeruginosa has led to the emergence of strains which, based on their degree of resistance to common antibiotics, have been defined as multidrug resistant, extended-resistant and panresistant strains. These strains are increasingly disseminated worldwide, progressively complicating the treatment of P. aeruginosa infections. In this scenario, the objective of the present guidelines was to review and update published evidence for the treatment of patients with acute, invasive and severe infections caused by P. aeruginosa. To this end, mechanisms of intrinsic resistance, factors favoring development of resistance during antibiotic exposure, prevalence of resistance in Spain, classical and recently appeared new antibiotics active against P. aeruginosa, pharmacodynamic principles predicting efficacy, clinical experience with monotherapy and combination therapy, and principles for antibiotic treatment were reviewed to elaborate recommendations by the panel of experts for empirical and directed treatment of P. aeruginosa invasive infections.

Figure 1

Election of empirical antibiotic treatment active against P. aeruginosa a) High bacterial load not surgically correctable (extensive pneumonia or pneumonia with necrosis/cavitation) b) Includes neutropenia < 500 cells/mm³ and treatment with corticoid doses >20 mg/kg during >3 weeks c)Treatment within the last 30-90 days with a β-lactam active against P. aeruginosa, admission during > 3-5 days in an hospitalization unit with a prevalence of MDR P. aeruginosa >10-20% or previous history of colonization/infection by MDR P. aeruginosa d) Initial loading dose followed by high doses administered as continuous (or extended) infusion during the first 48-72 h e) According to local epidemiology and susceptibility of possible previous isolates f) Monotherapy in case of urinary tract infection or venous catheter infection. Association with amikacin or fluoroquinolone (levofloxacin or ciprofloxacin) in situations with high bacterial load (pneumonia) g) Ciprofloxacin as treatment of choice for malignant external otitis, prostatitis and bronchial infection in patients with cystic fibrosis