title: Nosocomial transmission clusters and risk factors in Moraxella catarrhalis.
abstract: We report an objective examination of nosocomial transmission events derived from long-term (10-year) data from a single medical centre. Cluster analysis, based on the temporal proximity of genetically identical isolates of the respiratory pathogen Moraxella catarrhalis, identified 40 transmission events involving 33 of the 52 genotypes represented by multiple isolates. There was no evidence of highly transmissible or outbreak-prone genotypes. Although most clusters were small (mean size 3.6 isolates) and of short duration (median duration 25 days), clustering accounted for 38.7% of all isolates. Significant risk factors for clustering were multi-bed wards, and winter and spring season, but bacterial antibiotic resistance, manifested as the ability to produce a beta-lactamase was not a risk factor. The use of cluster analysis to identify transmission events and its application to long-term data demonstrate an approach to pathogen transmission that should find wide application beyond hospital populations.
authors.affiliation: Department of Biological Sciences, East Tennessee State University, Johnson City, TN, USA. levyf@etsu.edu
authors.forename: F
authors.initials: F
authors.lastname: Levy
authors.forename: S C
authors.initials: SC
authors.lastname: Leman
authors.forename: F A
authors.initials: FA
authors.lastname: Sarubbi
authors.forename: E S
authors.initials: ES
authors.lastname: Walker
mesh_terms: D016000:Cluster Analysis; D003428:Cross Infection / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D004196:Disease Outbreaks; D005838:Genotype; D017053:Infection Control; D001936:Moraxella catarrhalis / Q000145:classification / Q000187:drug effects / Q000235:genetics; D045828:Moraxellaceae Infections / Q000453:epidemiology* / Q000382:microbiology / Q000635:transmission; D012189:Retrospective Studies; D012307:Risk Factors; D012621:Seasons; D013997:Time Factors; D018440:beta-Lactam Resistance; D001618:beta-Lactamases / Q000378:metabolism
chemical_list: D001618:beta-Lactamases