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 alter the pattern of pathogens isolated from bacteraemic patients. We aimed to describe the frequency and seasonal pattern of bacterial isolates from blood, their antibiotic susceptibility, and patient outcome, in order to provide 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 blood culture performed, of whom 449 (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%; Neisseria meningitidis 44%; Salmonella typhi 17%. Despite an overwhelming association 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 temperature. A case of bacteraemia with Vibrio cholerae (serotype 01) was detected during a cholera outbreak in the rainy season. Although S. pneumoniae isolates 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. pneumoniae in bacteraemia in an area affected by HIV-1 and allows comparison of mortality by individual pathogens. It demonstrates a preserved seasonal pattern of bacteraemia for these major pathogens, despite an overwhelming association with HIV infection.

Aetiology of neonatal sepsis in Blantyre, Malawi: 1996-2001.

AIM: The aim of this retrospective study was to report causes, antibiotic resistance and outcome of neonatal sepsis (often fatal in developing countries) in Malawi. METHODS: All blood and cerebrospinal fluid isolates collected between January 1996 and December 2001 from inpatients aged 0-30 days with suspected sepsis at Queen Elizabeth Central Hospital, Blantyre, Malawi were reviewed. In vitro resistance to antibiotics commonly used in Malawi was assessed. Case fatality rate was analysed with respect to age, bacterial pathogen and infection site. RESULTS: A total of 801 bacteria were isolated from 784 neonates over 6 years-599 isolates from blood and 202 from cerebrospinal fluid. Overall, 54% of bacteria were gram-positive and 46% gram-negative. The commonest causes of neonatal sepsis were group B Streptococcus (17%) and non-typhoidal Salmonella (14%). In vitro antibiotic susceptibility to the first-line antibiotic combination of penicillin and gentamicin was 78% for all isolates, but in vitro sensitivities to gentamicin for Klebsiella spp and non-typhoidal Salmonella were only 33% and 53%, respectively. In-hospital case fatality rate was known for only 301 cases and was high at 48%. Group B Streptococcus was associated with the best outcome. Mortality was significantly higher if presentation was in the 1st week of life or if sepsis was caused by gram-negative bacteria. The causes of neonatal sepsis in this population show a different pattern from other studies in developing countries.

Surveillance of invasive infection in children and adults admitted to QECH, Blantyre, 1996-2002.

This is a report of blood CSF isolates from the adults medical and paediatric of wards QECH, Blantyre, cultured and identified at the Welcome Trust Research Laboratories during 1996-2002. The commonest causes of adults and children bacteraemia were non-typhoidal Salmonella (35% of all blood isolates for adults and children) and Streptococcus pneumoniae (14% and 13% respectively). Cryptococcus neoformans was the commonest isolates from CSF of adults with meningitis(67%) but was very rare in children. S.pneumoniae was the commonest cause of bacterial meningitis in children and adults (38% and 28% of all CSF isolates respectively). Haemophilus influenzae type b was also a common cause of meningitis in children (27%). Data of in vitro antibiotic sensitivity are also reported. A major concern is the recent marked rise of chloramphenicol resistance among Salmonella enteritidis and Salmonella typhimurium to over 80% resistance.