Establishing the diagnosis of chronic colonization with Pseudomonas aeruginosa of cystic fibrosis patients: Comparison of the European consensus criteria with genotyping of P. aeruginosa isolates

After antibiotic eradication treatment for a first ever Pseudomonas aeruginosa isolation, the European consensus criteria (ECC) are widely used to assess colonization status with P. aeruginosa in CF-patients. We evaluated to what extent genotyping (GT) of subsequent P. aeruginosa isolates could predict/assess chronic colonization (CC), in comparison with the ECC. Over a 14-year period, sputa were cultured from 80 CF-patients (age range: 2–51 years), from a first ever isolation of P. aeruginosa onwards. Patients with a positive culture for P. aeruginosa received antibiotic eradication treatment. For the 40 patients for whom three or more P. aeruginosa isolates were available, these isolates were genotyped. According to the ECC, 27 out of the 40 patients (67.5%) became CC during the study period (ECC-positive patients). Genotyping confirmed persistence of the same genotype for 25 of these ECC-positive patients. Genotyping indicated persistence of the same genotype for at least two subsequent isolates for 5 out of 13 ECC-negative patients. Culture-positivity characteristics of the 27 ECC-positive patients corresponded well to those of the 30 GT-positive patients, with an overall higher number of positive cultures as well as a shorter interval in between first and second isolate compared to ECC-negative and GT-negative patients. Genotyping indicated persistence of the same genotype on average 9.3 months earlier than CC according to the ECC (P