A total of 90 samples comprising powdered infant formulas (n=51), follow-up formulas (n=21), and infant foods (n=18) from 15 domestic and imported brands were purchased from various retailers in Klang Valley, Malaysia and evaluated in terms of microbiological quality and the similarity of rehydration instructions on the product label to guidelines set by the World Health Organization. Microbiological analysis included the determination of aerobic plate count (APC) and the presence of Enterobacteriaceae and Cronobacter spp. Isolates of interest were identified using ID 32E (bioMérieux France, Craponne, France). In this study, 87% of powdered infant formulas, follow-up formulas, and infant foods analyzed had an APC below the permitted level of <10(4) cfu/g. These acceptable APC ranged between <10(2) to 7.2×10(3) cfu/g. The most frequently isolated Enterobacteriaceae was Enterobacter cloacae, which was present in 3 infant formulas and 1 infant food tested. Other Enterobacteriaceae detected from powdered infant and follow-up formulas were Citrobacter spp., Klebsiella spp., and other Enterobacter spp. No Cronobacter species were found in any samples. Rehydration instructions from the product labels were collated and it was observed that none directed the use of water with a temperature >70°C for formula preparation, as specified by the 2008 revised World Health Organization guidelines. Six brands instructed the use of water at 40 to 55°C, a temperature range that would support the survival and even growth of Enterobacteriaceae.
Next Generation Sequencing (NGS) combined with powerful bioinformatic approaches are revolutionising food microbiology. Whole genome sequencing (WGS) of single isolates allows the most detailed comparison possible hitherto of individual strains. The two principle approaches for strain discrimination, single nucleotide polymorphism (SNP) analysis and genomic multi-locus sequence typing (MLST) are showing concordant results for phylogenetic clustering and are complementary to each other. Metabarcoding and metagenomics, applied to total DNA isolated from either food materials or the production environment, allows the identification of complete microbial populations. Metagenomics identifies the entire gene content and when coupled to transcriptomics or proteomics, allows the identification of functional capacity and biochemical activity of microbial populations. The focus of this review is on the recent use and future potential of NGS in food microbiology and on current challenges. Guidance is provided for new users, such as public health departments and the food industry, on the implementation of NGS and how to critically interpret results and place them in a broader context. The review aims to promote the broader application of NGS technologies within the food industry as well as highlight knowledge gaps and novel applications of NGS with the aim of driving future research and increasing food safety outputs from its wider use.