Esterase electrophoresis: a molecular tool for studying the epidemiology of Branhamella catarrhalis nosocomial infection.

A new epidemiologic typing method based on electrophoresis of esterases had been developed for differentiating between clinical isolates of Branhamella catarrhalis. Twenty-two epidemiologically significant strains obtained from three Chest Units, a Paediatric Intensive Care Unit and a Paediatric Unit were compared with 54 randomly selected strains and 4 reference strains, including the species type strain, ATCC 25238. Thirty-four distinct zymotypes were characterized by polyacrylamide-agarose gel electrophoresis of the 80 strains. One infrequent zymotype was found in 2 neonates and another in 2 adults with nosocomial bronchopulmonary infections, suggesting the nosocomial spread of 2 outbreak strains of B. catarrhalis. A more frequent zymotype was isolated from 3 neonates with nosocomial bronchopulmonary infection and from 2 children with nosocomial rhinopharyngitis. The remaining 12 epidemiologically significant strains were of varied zymotypes. This work demonstrates that esterase electrophoresis is a suitable, readily reproducible, stable typing system applicable to the wide range of strains found in B. catarrhalis nosocomial infections.