Affiliation:
1. Centro Nacional de Microbiología, Instituto de Salud Carlos III, Majadahonda
2. Department of Microbiology, Hospital Universitario Ramón y Cajal, Madrid, Spain
Abstract
ABSTRACT
The persistence and variability of 188
Haemophilus influenzae
isolates in respiratory tract of 30 cystic fibrosis (CF) patients over the course of 7 years was studied. Antibiotic susceptibility testing, DNA fingerprinting, and analysis of outer membrane protein profiles were performed on all isolates. A total of 115 distinct pulsed-field gel electrophoresis profiles were identified. Ninety percent of patients were cocolonized with two or more clones over the studied period. A third of the patients were cross-colonized with one or two
H. influenzae
strains; 11% of the clones persisted for 3 or more months. Biotype, outer membrane protein profiles, and resistance profiles showed variation along the studied period, even in persisting clones. Four isolates (2.1%) recovered from 3 patients were type f capsulate, with three of them belonging to the same clone. β-Lactamase production was detected in 23.9% of isolates while 7% of the β-lactamase-negative isolates presented diminished susceptibility to ampicillin (β-lactamase-negative ampicillin resistance phenotype). Remarkably, 21.3% of the
H. influenzae
isolates presented decreased susceptibility to ciprofloxacin, which was mainly observed in persisting clones. Of the
H. influenzae
isolates from CF patients, 18 (14.5%) were found to be hypermutable in comparison with 1 (1.4%) from non-CF patients (
P
< 0.0001). Ten patients (33.3%) were colonized by hypermutable strains over the study period. A multiresistance phenotype and long-term clonal persistence were significantly associated in some cases for up to 7 years. These results suggest that
H. influenzae
bronchial colonization in CF patients is a dynamic process, but better-adapted clones can persist for long periods of time.
Publisher
American Society for Microbiology
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5. Characterization of Non-Type B
Haemophilus influenzae
Strains Isolated from Patients with Invasive Disease
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