The problem in Africa
Salmonella infections are among the commonest bacterial isolates from blood cultures throughout Africa. WHO estimates that 12.5 million cases of typhoid fever occur annually world-wide. Most cases are in Asia, but typhoid remains endemic in some areas of Africa, and epidemics are also reported. Invasive non-typhoid salmonella (NTS) infections, a long-standing and common cause of illness and death in African infants and children, have further increased among children and significantly increased among adults as a result of the HIV epidemic.
Whenever an African patient has few signs, yet is ill with a fever, invasive Salmonella infection (either typhoid or non-typhoid) is high on the list of differential diagnoses. Host factors (age, nutrition, malaria, HIV) and local environmental factors will determine whether typhoidal or non-typhoidal disease is most likely. The management of Salmonella sepsis has been complicated by the recent emergence of multidrug resistance.
The organism
Salmonellae are Gram-negative, motile, facultatively anaerobic bacilli, which produce acid on glucose fermentation, reduce nitrates and do not ferment lactose. They can be grown easily on a variety of media. Use of a selective agar, such as XLD or MacConkeys, may be useful if attempting to differentiate them from other organisms, for example, when culturing faeces.