Non-typhoidal salmonella bacteraemia among HIV-infected Malawian adults: high mortality and frequent recrudescence

Abstract

Non-typhoidal salmonella (NTS) bacteraemia is a common, recurrent illness in HIV-infected African adults. We aimed to describe the presentation and outcome of NTS bacteraemia, the pattern of recurrence, and to determine whether recurrence results from re-infection or recrudescence. One hundred consecutive adult inpatients with NTS bacteraemia in Blantyre, Malawi, were treated with chloramphenicol. Survivors were prospectively followed to detect bacteraemic recurrence. Index and recurrent isolates were typed by antibiogram, pulsed-field gel electrophoresis and plasmid analysis to distinguish recrudescence from re-infection. Inpatient mortality was 47%, and 1-year mortality was 77%. A total of 77 out of 78 cases were HIV positive. Anaemia was associated with inpatient death, and several features of AIDS were associated with poor outpatient survival. Among survivors, 43% (19/44) had a first recurrence of NTS bacteraemia at 23–186 days. Among these, 26% (5/19) developed multiple recurrences up to 245 days. No recurrence was seen after 245 days, despite follow-up for up to 609 days (median 214). Suppurative infections were not found at presentation, and were only seen twice at recurrence. Index and recurrent paired isolates were identical by phenotyping and genotyping, consistent with recrudescence, rather than re-infection. NTS bacteraemia has a high mortality (47%) and recurrence (43%) rate in HIV-infected African adults. Recurrence is caused by recrudescence rather than re-infection. As focal infections were rarely found, recrudescence may often be a consequence of intracellular tissue sequestration. There is an urgent need for improved primary treatment and secondary prophylaxis in Africa.