Bacteraemia and mortality among adult medical admissions in Malawi - Predominance of non-typhi Salmonellae and Streptococcus pneumoniae

Objectives: The high seroprevalence of HIV in Malawi might be expected to a lter the pattern of pathogens isolated from bacteraemic patients. We aimed to describe the frequency and seasonal pattern of bacterial isolates from b lood, their antibiotic susceptibility, and patient outcome, in order to pro vide data on which to base empirical antibiotic therapy and further studies of pathogenesis. Methods: Over a 12-month period, blood cultures were taken from all febrile adult medical admissions to Queen Elizabeth Central Hospital, Blantyre. Results: A total of 2789 out of 9298 adult general medical admissions had b lood culture performed, of whom 119 (16.1%) grew significant pathogens. Non -typhi salmonellae (NTS) (37%) and Streptococcus pneumoniae (30%) were the two commonest isolates. Mortality was 18% among general medical admissions and 38% among bacteraemic patients. Mortality for individual pathogens was: NTS 33%; S. pneumoniae 36%; Escherichia coli 54%; Klebsiella spp. 58%; Nei sseria meningitidis 44%; Salmonella typhi 17%. Despite an overwhelming asso ciation between the major pathogens and HIV infection (95% of S. pneumoniae cases and 92% of NTS cases were seropositive for HIV), a seasonal pattern was preserved. Streptococcus pneumoniae was more frequently isolated in the cold dry months, while STM isolates increased following a rise in temperat ure. A case of bacteraemia with Vibrio cholerae (serotype 01) was detected during a cholera outbreak in the rainy season. Although S. pneumoniae isola tes were relatively susceptible to penicillin (88%) and chloramphenicol (74 %), S. typhimurium isolates were fully susceptible only to chloramphenicol. Conclusions: This large study confirms the dominance of NTS and S. pneumoni ae in bacteraemia in an area affected by HIV-1 and allows comparison of mor tality by individual pathogens. It demonstrates a preserved seasonal patter n of bacteraemia for these major pathogens, despite an overwhelming associa tion with HIV infection. (C) 2001 The British Infection Society.