Beta-lactamase producing Haemophili occurrence in clinical materials and carriage in healthy children.

Beta-lactamase production was investigated in 126 H. influenzae and 15 H. parainfluenzae strains isolated in various infections. In H. influenzae the rate of beta-lactamase positive strains was 5.6%, in non-encapsulated strains it was higher (9.7%) than in capsule bearing strains (3.1%). Among beta-lactamase producing H. influenzae strains biotype II was predominant, whereas biotype I prevailed in beta-lactamase positive strains of H. parainfluenzae. A study undertaken in 101 children of a day-care nursery revealed 16.8% carriers of beta-lactamase producing Haemophili. Among the isolated strains we found the double number of H. parainfluenzae than H. influenzae strains showing beta-lactamase activity. This result supports the hypothesis of H. parainfluenzae being the reservoir of resistances plasmids in Haemophili.