In this study we report the pattern of bacteraemia amongst severely malnourished children in Mulago hospital, Uganda, where the prevalence of HIV infection among paediatric patients is high . The prevalence of bacteraemia of 17% among the severely malnourished children in the current study is about the same as the 13% reported by Philipps and Wharton  in the same hospital in the pre-HIV/AIDS era, and comparable to the 18.7% recently reported from Nairobi by Nooran et al . Nonetheless, a positive HIV test did not significantly increase the prevalence of bacteraemia. This is in keeping with several studies of bacteraemia in the HIV/AIDS era [8, 9], but different from Berkeley's  study in which HIV and malnutrition were independent risk factors for bacteraemia. This difference might be due to the fact that the current study was carried out on only severely malnourished children with a high risk of dying.
Gram negative organisms, especially non typhoidal salmonella species, were the predominant cause of bacteraemia in severely malnourished children, supporting early results from Uganda  and recent studies from Kenya, Malawi and Ethiopia [8, 11–13].
Although there was no difference in the types of bacterial organisms by HIV status, blood specimens from severely immuno-suppressed children were more likely to grow Salmonella enteriditis. The mechanism for this is not very clear and may include the difficulty in clearing salmonella infections from infected macrophages and weak immune system, HIV may predispose the host to infection with Salmonella enteriditis  and this, in turn, promotes the production of HIV in the macrophages of the gastrointestinal tract mucosal cells, thus completing a vicious cycle. Although some of the non typhoidal salmonella in the current study were unusual, they were all from the blood cultures and from patients residing in the slums of Kampala city.
We also found a high proportion of Gram positive organisms particularly Staphylococcus aureus. The reason for the predominance of Staphylococcus aureus in this series is not clear as there was no associated skin ulceration. It is possible that vitamin A deficiency in severely malnourished patients  might have contributed to this. Several studies have suggested that vitamin A deficiency predisposes to Staphylococcus aureus through phagocyte dysfunction and decreased complement activity . In Uganda, the national health program includes Vitamin A supplementation twice a year for all the children below 5 years of age, from the age of 9 months. Vitamin A is also routinely given as treatment to all children suffering from measles, tuberculosis, severe malnutrition and severe pneumonia. Other possible risk factors that could have contributed to Staphylococcus aureus include concurrent viral infections, chronic lung diseases in HIV positive children and prior hospitalization. However, none of the children had been hospitalized two weeks prior to the study.
We found a very low proportion of H. influenzae infection in these children and this may be explained by the incorporation of HiB vaccine into the expanded programme on immunization (EPI) in Uganda from 2002.
Our study demonstrated high bacterial resistance to commonly used antibiotics such as co-trimoxazole, ampicillin and chloramphenicol among both HIV positive and HIV negative children. These findings raise great concern as ampicillin, in combination with gentamicin, is routinely given to all children admitted with severe malnutrition at Mulago hospital  However there was high susceptibility to ciprofloxacin, ceftriaxone and gentamicin regardless of HIV test status and this concurs with recent finding from Kenya .
Surprisingly, blood isolates from HIV infected children were more susceptible to ampicillin and chlorampenicol than those from HIV negative children. This finding is at odds with results from an Ethiopian study which reported that isolates recovered from HIV-positive patients were significantly resistant to many of the antibiotics tested when compared to the isolates from HIV-negative patients . However a recent study from Thailand, of antimicrobial susceptibility tests of bacterial pathogens from blood cultures of HIV-infected patients, found that Salmonella species were highly sensitive to amoxicillin/clavulanate, gentamicin, and ciprofloxacin . The difference in sensitivity patterns of salmonellae species may probably be attributed to difference in accessibility and use of antibiotics.
These results leave us in an important dilemma. The organisms exhibited very low in vitro susceptibility to one of the drugs (ampicillin) currently recommended in combination with gentamicin for the management of presumed bacteraemia in severely malnourished children. However they showed high susceptibility to gentamicin and ciprofloxacin. This calls for further studies to determine the most feasible combination of antibiotics for the management of bacteraemia in severely malnourished children in this setting. In conformity with other studies, our study did not find clinical signs or symptoms that could be reliably used to predict bacteraemia [9, 20].
The mortality among severely malnourished children with bacteraemia of 28.9% was comparable to findings from other centres in sub-Saharan Africa [8, 11, 13]. Overall, there was no significant association between bacteraemia and mortality in this vulnerable group of children. However among the children with bacteraemia, mortality was much higher in the HIV-positive than among the HIV-negative, table 5. This underscores the importance of early diagnosis and use of efficacious antibiotics . In the current study we did not observe any significant relationship between outcome and age of the children, which is consistent with results of a recent study from Kenya .
A limitation of this study is the lack of information on prior use of antimicrobials and previous history of hospitalization that may be associated with bacterial resistance and types of isolates. However, the information on underlying diseases was collected using the clinical history, physical examination laboratory tests and chest x-ray. We used isolates from two samples of children form two different years. However, the severely malnourished children from the two samples came from the same community served by the hospital and the same methodology was used at the same seasonal periods, the same hospital setting and the same laboratories. The study was conducted in only one hospital in the country and may not be representative of the larger Ugandan population.
Further more, the selection of specific seasons may have a bearing on the spectrum of pathogens identified as well as on the severity of malnutrition. The study was carried out between September and December, which is the peak season for severe malnutrition in Uganda. Unfortunately, it was not possible to determine the effect of seasonality on non-typhoidal salmonellae.