[Bacteremia caused by Haemophilus influenzae with special reference to its relation to HIV infection]

The association between infection by Haemophilus influenzae and infection by the human immunodeficiency virus (HIV) has been clearly demonstrated. However, some characteristics of this association still remain poorly defined.

The medical records of all adult patients admitted to a general hospital over a period of four years with blood cultures positive for Haemophilus influenzae were reviewed. Patients were grouped according to whether HIV infection or no evidence of HIV infection existed. Clinical and epidemiologic data were collected and compared. The main features of data corresponding to seropositive patients are reported.

Of a total of 29 cases of bacteremia by Haemophilus influenzae, 19 were diagnosed in adults: 5 in patients with HIV infection and 14 in patients without HIV infection. Over the following 18 months one additional case was reported. The incidence (calculated in cases per 100,000 people/year) was 1.9 in the general population, 1.5 in adults, 70 in adults with HIV infection and 360 in AIDS patients. All the cases diagnosed in adults below the age of 30 years were reported in HIV carriers. Five of the 16 (31%) H. influenzae strains tested were resistant to ampicillin, with a significant difference being found between those isolated from HIV positive patients (4/5) and from HIV negative patients (1/11). No patient with HIV infection died during the episode. But five of the HIV negative adults died.

HIV infection seems to be frequent risk factor for bacteremia by Haemophilus influenzae. It should always be considered on diagnosis in adults under the age of 30. Likewise, the high probability of resistance to ampicillin should also be taken into account for the empiric treatment.