Isolation and PCR detection of Enterobacter sakazakii in South African food products, specifically infant formula milks

Abstract

Enterobacter sakazakii has recently been identified as an opportunistic pathogen. The current culture-dependent detection methods for these bacteria are time-consuming and in this study a PCR method for the detection of E. sakazakii in South African food products, including an internal amplification control (IAC) was developed. DNA was isolated and amplified from the products and they were plated on selective growth media after pre-enrichment and enrichment in Enterobacteriaceae enrichment broth. Four of the 22 products tested positive for the presence of E. sakazakii, confirmed by PCR detection and growth on selective media. The PCR method proved effective in detecting E. sakazakii in South African products after three days and could serve as an alternative for traditional microbiological techniques.

Incidence of Cronobacter sakazakii in Powdered Infant Formula Milk Available in Malaysia

“…Based on sequencing results, all 12 isolates selected from 9 of 72 PIF samples (12.5%) investigated in this study were identified as Cronobacter (Figure 1). The incidence of 12.5% Cronobacter contamination of PIF in Malaysia was almost in agreement with reports of Cawthorn et al (2008) and Witthuhn et al (2006) who found the prevalence of Cronobacter in South African PIF were 14 and 18%, respectively. Muytjens et al (1988) also reported that 14% of PIF samples were positive for Cronobacter contamination.…”

Development of a loop-mediated isothermal amplification assay for detection of Cronobacter spp. (Enterobacter sakazakii)

“…Until recently, real-time PCR approaches have been widely used in detection of Cronobacter spp. strains (Liu et al 2006;Witthuhn et al 2007). Although real-time PCR assay had many advantages over conventional PCR that include higher sensitivity and easy standardization, it nevertheless has many disadvantages as well.…”

“…It has been suggested that powdered milk-based infant formulas may serve as a transmission route. Thus, detection of the pathogen has been an important subject in clinical research and food safety (ICMSF 2002;Liu et al 2006;Witthuhn et al 2007).…”

Species of Cronobacter – A review of recent advances in the genus and their significance in infant formula milk

“…All of these products, however, met the prevailing Codex Alimentarius Commission (CAC) microbiological specifications for coliform counts in powdered IFM (less than 3 cfu g À1 ) (Muytjens et al, 1988;Van Acker et al, 2001). Evaluation of commercial powdered IFM and baby foods available on the South African market revealed the presence of Cronobacter in 18% of the products tested (Witthuhn, Kemp, & Britz, 2006).…”