Résumé
Objectives:Pseudomonas aeruginosa(Pa) is a major pathogen able topersist in CF airways. Population genetics ofPais marked by diversity,success of epidemic high-risk clones (EHRC) and, in CF, the description ofinternational epidemic clones (IEC). Considering the absence ofPagenotyping data in France, our objectives were to determinePafirstcolonization genotypes, and to study genotype evolution over time.Methods:A total of 266Pastrains, including the strain of first colonization,in 52 CF patients (140 samples) were collected over a 6-year period(Montpellier University Hospital). Isolates from the same patient werecompared by multiplex rep-PCR (MR-PCR) and Multilocus SequenceTyping (MLST) performed for one isolate per MR-PCR profile. Strainsisolated in several patients and sharing identical STs, were compared byMR-PCR or Pulsed-Field Gel Electrophoresis (PFGE).Results:A total of 48 STs were identified: 9 non-described, 22 described inCF in the world, and 17 described in our institution (environmental andnon-CF clinicalPa). 15 patients were colonized by 6 IEC, of whom 3 by theclone C (ST17). 14 STs, including EHRC ST395, were retrieved in at least 2patients, and PFGE showed cross-transmission among 4 sibling pairs. Thefirst colonizingPapopulation encompassed 41 STs. InitialPaisolates wereeradicated in 50% of the patients. Different STs (up to 5) were identifiedover time for 12 out of the 26 patients with successivePa, with initial strainreplacement in most cases (92%). Intra-sample diversity was observed in 3cases, including one case of firstPaisolation.Conclusion:We conducted the first MLST characterization ofPain FrenchCF patients. No major clones were identified and we observed a highgenetic diversity among initialPaisolates. No specific clones wereidentified among persistent and transientPapopulations.Pacolonizationappears complex and dynamic, with cases of successive transientcolonization byPaof different STs