Molecular detection of Enterobacter spp. and other related species in powdered milk infant formula and milk powder

Abstract

A total of 60 powdered milk infant formula and milk powder samples were obtained from different localities in Qena Governorate, Egypt, to be evaluated for presence of Enterobacter and closely related species using FDA procedure. Ten out of 60 samples were contaminated with Enterobacter spp. and other Enterobacteriaceae. The obtained isolates were biochemically identified as Enterobacter spp., Klebsiella pneumoniae, Escherichia coli, Citrobacter spp. Further characterization was performed using 16S rRNA sequence analysis; it was a pivotal to confirm the identity of the isolates especially in imprecise identification of phenotypic method in some isolates like Enterobacter hormaechei, Klebsiella quasipneumoniae, and Acinetobacter vivianii. Results revealed the contamination of powdered milk infant formula with E. hormaechei which makes it a matter of concern. According to the best of our knowledge, Enterobacter hormaechei and Klebsiella quasipneumonia were isolated for the first time in Egypt. The phylogenetic analysis proved the close relation between our isolates in amplification of partial 16S rRNA gene. Practical applications As many neonates depend on powdered infant formula in their feeding as well as milk powder is a fundamental component of many infants diet, our study evaluated these products for the presence of pathogens of safety concern. This study focused on Enterobacteriaceae family members other than Salmonella and Cronobacter sakazakii using 16S rRNA gene for identification and differentiation of the closely related species.

Safety and quality aspects of whole and skimmed milk powders

“…25 grams of each powdered milk sample was mixed with 225 ml of buffered peptone water (Oxoid, CM0509) and kept in an incubator at 37°C for 18 ±2 h. Only 0.1 ml of each pre-enriched buffered peptone water was transferred into 10 ml of modified Lauryl Sulfate Tryptone broth (mLST; Oxoid CM1133) with a vancomycin supplement (10 mg/L; Oxoid, SR0247E); these broths were incubated at 44 ±0.5°C/24 h. Then, from all the enriched cultures, a loopful was streaked onto Violet Red Bile Glucose Agar (Oxoid, CM0485) and the plates were incubated at 37°C for 24 h. Finally, five red and/or purple colonies circled by a halo of purple color were picked up and streaked onto plates of Tryptic Soya Agar (TSA; Oxoid, CM0876), which were incubated for 72 h at 25°C. Each yellow and non-yellow pigmented colony on the TSA was picked off for further identification (ISO/IDF, 2006;El-Zamkan and Mohamed, 2018).…”

Development of an isothermal recombinase‐aided amplification assay for the rapid and visualized detection of Klebsiella pneumoniae

“…Klebsiella pneumoniae belongs to class B of three types of pathogens (A, B and C), classified by FAO/WHO (2004) because of its severe morbidity and high mortality. 8 Moreover, K. pneumoniae is considered an important pathogen of environmental bovine mastitis, 4 especially in high-yield cows, 27,28 which may pose a potential threat to food safety and public health. Therefore, the rapid, on-site and accurate detection of K. pneumoniae is needed to reduce the risk factor caused by K. pneumoniae prevalence.…”

Rapid quantification of coliforms in ready‐to‐eat foods using lateral‐flow immunochromatographic assay

“…Citrobacter koseri might be causative agent of meningitis, ventriculitis, and brain abscess (Martínez‐Lage et al, 2010). Enterobacter cloacae is associated with neonatal infections (El‐Zamkan & Mohamed, 2018). Both Klebsiella sp.…”