Antibiotic resistance in Salmonella infections

Abstract

INTRODUCTION Salmonella infections in humans can range from a self-limiting gastroenteritis, usually associated with non-typhoidal Salmonella (NTS), to typhoid fever with complications such as a fatal intestinal perforation. The World Health Organization (WHO) estimates that the annual global incidence of typhoid fever is about 21 million cases with a mortality of 1% (Crump et al ., 2004). This may be an underestimate because typhoid is predominantly a disease of developing countries, where not all cases present to the healthcare services and data collection may be difficult. In addition, financial constraints limit outbreak investigation and antibiotics are often widely available without prescription. Not only does this compound problems with data gathering, but it is likely to add to the burden of resistant disease circulating in the community. The situation is even less clear for NTS because most patients do not need to consult the health services. Despite this, as reported in 1999 in the USA alone there were an estimated 1.4 million cases of NTS infection annually, resulting in approximately 600 deaths (Mead et al ., 1999). There is no doubt that antibiotic resistance in Salmonella infections poses a major threat to human health, especially in cases of invasive NTS in immunocompromised patients and in typhoid fever. The cost of resistance in human terms is shown in Table 2.1. There is also a potential increase in the cost of food production.