Outbreak of multiresistant non-encapsulated Haemophilus influenzae infections in a pulmonary rehabilitation centre.

15 out of 21 patients admitted to a pulmonary rehabilitation centre were infected with a non-encapsulated strain of Haemophilus influenzae. All isolates showed identical outer membrane protein patterns, harboured a 40 MD plasmid, produced beta-lactamase, and were resistant to amoxycillin, co-trimoxazole, chloramphenicol, and tetracycline. The strain was first isolated from sputum of another 3 patients in the same hospital ward. 2 of them later introduced it into the rehabilitation centre. The strain spread among the other patients over the next 2 months. The absence of a common iatrogenic source of the organism and its slow spread indicate that the most likely means of transmission was person to person.