Microbiological risk factors in food - Enterobacter sakazakii

摘要

Enterobacter sakazakii - previously known s a yellow-pigmented E. cloacae - has, since 1980, been singled out as a unique species. This new classification is based on the differences from E. cloacae in DNA relatedness and biochemical reactions. Little is known about the presence of E. sakazakii in the environment. Most of the strains reported in literature have been isolated from clinical sources. Bacteria of Enterobacter species are considered to be opportunistic pathogens and rarely cause diseases in humans. In recent years there have been about 60 documented cases of E. sakazakii infections, but this number is probably underestimated because many clinical laboratories do not test for this microorganism and, in addition, an official reporting system has not been adopted in most countries. The populations at greatest risk of E. sakazakii infection are preterm, low-birth weight or immunocompromised infants, especially those hospitalized in neonatal intensive care units. The bacteria can cause life-threatening infections in neonates such as bacteraemia, enterocolitis or meningitis and survivors often suffer from neurological complications. Although the reservoir of E. sakazakii is unknown, the growing number of outbreaks of infection among this susceptible population has provided evidence that milk-based powdered infant formulas often serve as a source of infection. Unlike liquid formula products, dried milk powders are not sterile. In case of the presence of E. sakazakii, this microorganism can survive a long time on blenders, and, if not properly cleaned, can become a source of infection. The high mortality rate, the severity of the infection in infants and lack of information about the ecology and pathogenicity of this microorganism, has resulted in this bacteria becoming an object of interest to scientists worldwide.