Haemophilus infiuenzae Polyarthritis in an Adult: An Analysis of Serotype b Strains

A 61-year-old man who presented with clinical features suggestive of septic arthritis was found to have acute septic polyarthritis due to Haemophilus irifluenzae (type b). The clinical and labo-ratory diagnoses of the case are presented, and the isolates of H. influenzae are characterized. Four isolates recovered from different sites had identical minimal inhibitory drug concentrations, outer membrane protein patterns, and genomic DNA restriction digests. These observations in-dicate that the disseminated infection arose from a single source. The patient developed anti-body to several outer membrane proteins, particularly the P6 protein. Haemophilus influenzae is a well-recognized pathogen that causes a number of pediatric infections, including septic ar-thritis [1-4]. Serious disease due to H. irftuenzae in adults is far less common; for example, this organism causes <1% of all adult cases of bacterial septic arthritis (2%of such cases when gonococcal arthritis is excluded). This report describes the 32nd known case of septic arthritis caused by H. influen-zae in an adult [5-9]. Four separate isolates were recovered