Achromobacter xylosoxidans is a ubiquitous Gram‐negative non‐fermenting rod, recently characterized as an emerging pathogen in cystic fibrosis (CF) patients. Its pathogenic potential and prevalent transmission routes are still unclear. This study investigated the PFGE genetic pattern and antimicrobial resistance profile of 42 A. xylosoxidans isolates obtained over 4 years from the respiratory tract of 22 CF patients. By genotypic analysis, 31 isolates were attributed to 8 distinct PFGE patterns (A–H), whereas 11 isolates were not typable because their DNA was not restricted by XbaI and DraI restriction enzymes. The majority of the isolates showed multidrug resistance; imipenem and piperacillin were the most active drugs. During the course of A. xylosoxidans chronic infection forced expiratory volume and body mass index values were not significantly lowered. The demonstration of widespread antibiotic resistance underscores the importance of antibiogram‐directed therapy. Our data suggest that in some cases the infection may have been acquired from other patients or from a common contaminated source. Further epidemiological studies may be important for the design and implementation of prophylactic measures in CF centers.

The etiopathogenesis of Crohn's disease (CD) is still controversial: several genetic, immunologic, and environmental factors, including some bacteria, have been implicated. This study has been devised to assess the involvement of Escherichia coli in CD. Seven E. coli strains were isolated from 14 biopsies obtained from ileocolic ulcers of patients affected by inflammatory bowel disease (IBD), including six with ulcerative colitis and eight with CD. Five strains, exclusively isolated from CD patients, were found inside mucosal cells. Different PCR techniques (for chuA, yjaA, TspE4.C2, escV, and bfpB genes) were performed and PFGE was carried out to characterize these bacteria in comparison with other E. coli strains isolated from non-IBD specimens. The correlation of these characters with bacterial invasiveness on intestinal (Caco-2) and phagocytic (U937) cells was assessed. Overall our pilot data suggest that five among eight strains isolated from CD patients belonged to the adherent-invasive E. coli (AIEC) group, and were invasive on Caco-2 cells and resistant to phagocytosis. These findings suggest that these bacteria could be considered target organisms whose elimination could reduce the intestinal inflammatory process and CD progression.

Pseudomonas aeruginosa accounts for about one half of all pulmonary infections of cystic fibrosis (CF) patients. In this study, we analyzed 135 P. aeruginosa strains isolated from the expectorations of 55 CF adult patients attending a CF referral center over a period of five years. We assessed the genotype of the strains by pulsed-field gel electrophoresis (PFGE) and analyzed some phenotypic characteristics, such as O serotype, enzyme and mucous production, antibiotics susceptibility, and motility. PFGE allowed the typification of 97.1% of strains, revealing the presence of nine different genomic patterns. The pattern indicated as B was the most frequent, whereas patterns H and I were the most uncommon. Serotyping failed to identify 37.8% of strains and 29 out of 55 patients harbored almost one non-typable (NT) strain. During the five years of the study, we observed a progressive reduction of O6 and O10 types, but an increase of the O1 type and of NT strains. Most strains produced protease, hemolysin, and gelatinase, and were mobile. Several patients harbored the same serotype or genotype in sequential isolates, though characterized by a different susceptibility to antimicrobials. We did not observe a relationship between bacterial genotype and phenotype. This could be due to the fact that PFGE is not sensitive enough to detect subtle genotypic differences. The epidemiological importance of the genotypic characterization of bacteria-colonizing CF subjects and the surveillance measures to be adopted in CF centers are briefly discussed.