title: Haemophilus influenzae in children with cystic fibrosis: antimicrobial susceptibility, molecular epidemiology, distribution of adhesins and biofilm formation.
abstract: Haemophilus influenzae commonly infects the respiratory tract of patients with cystic fibrosis (CF), early in childhood. In this investigation, 79 H. influenzae isolates were recovered from the respiratory secretions of 64 CF patients (median age: 5 years) included in a 5-year follow-up study. Fifteen of the 64 patients contributed two or more H. influenzae isolates overtime. Serotyping, antibiotic susceptibility testing, genotyping, detection of both hmwA and hia adhesin genes and hypermutable strains was carried out. Biofilm formation ability was investigated. Most strains (72/79, 91.2%) were nonencapsulated or nontypeable (NTHi). Resistance to ampicillin (13.9%) and imipenem (17.7%) was the most detected. Few isolates (2.5%) exhibited the hypermutable phenotype. The NTHi strains showed 55 different genotypes, but 19 clusters of closely related strains were identified. Nine clusters included strains that cross-colonised several patients over a long-time period (mean: 3.7 years). Most patients with sequential isolates harboured strains genetically unrelated, but persistent colonisation with the same clone was observed in 37.5% of patients. Over 45% of NTHi strains contained hmwA-related sequences, 26.3%, hia, 8.3% both hmwA and hia, while 19.4% lacked both. A significant association was found between occurrence of an adhesive gene (irrespective of which) and both persistence (P<0.0001) and long-term cross-colonisation (P<0.0001). Mean biofilm level formed by the persistent strains was found significantly increased compared to non-persistent ones (P<0.0001). Hia-positive strains produced significantly more biofilm than hmwA-carrying strains (P<0.01). Although a high turnover of NTHi strains in FC patients was observed, distinct clones with increased capacity of persistence or cross-colonisation occurred.
authors: Department of Infectious, Parasitic and Immune-mediated Diseases, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
authors: Rita
authors: R
authors: Cardines
authors: Maria
authors: M
authors: Giufrè
authors: Arianna
authors: A
authors: Pompilio
authors: Ersilia
authors: E
authors: Fiscarelli
authors: Gabriella
authors: G
authors: Ricciotti
authors: Giovanni
authors: G
authors: Di Bonaventura
authors: Marina
authors: M
authors: Cerquetti
mesh_terms: D018829:Adhesins, Bacterial / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D018441:Biofilms / Q000254:growth & development*; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000150:complications* / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics; D016521:Electrophoresis, Gel, Pulsed-Field; D005500:Follow-Up Studies; D005838:Genotype; D006192:Haemophilus Infections / Q000150:complications / Q000382:microbiology*; D006193:Haemophilus influenzae / Q000145:classification / Q000187:drug effects / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D007223:Infant; D008826:Microbial Sensitivity Tests; D009154:Mutation; D010641:Phenotype; D012137:Respiratory System / Q000382:microbiology; D055815:Young Adult
chemical_list: D018829:Adhesins, Bacterial; D000900:Anti-Bacterial Agents; C117431:HMW1 protein, bacteria; C117432:HMW2 protein, bacteria; C429644:Hia adhesin