Prevalence and Genetic Diversity of Cronobacter Species Isolated From Four Infant Formula Production Factories in China.

Yan Lu,Changguo Li,Peng Liu,Xiaoxi Xu,Miao Sha,Jingwen Gao,Karl R Matthews,Jingquan Fang

doi:10.3389/fmicb.2019.01938

Abstract

The aim of this study was to investigate the prevalence and genotypic characteristics of Cronobacter isolated from powdered infant formula (PIF) manufacturing facilities and to identify a potential source of contamination. A total of 42 Cronobacter isolates (5%) were detected in 835 environmental samples collected during the surveillance study. These isolates included C. sakazakii (n = 37), C. malonaticus (n = 3), and C. turicensis (n = 2). The isolates were divided into 14 sequence types (STs) by multi-locus sequence typing (MLST) and 21 pulsotypes (PTs) using pulsed-field gel electrophoresis (PFGE). The dominant C. sakazakii sequence types were ST3 (n = 12) and ST21 (n = 10), followed by ST136 (n = 6). The major PTs were PT22 (n = 12) and PT17 (n = 4) based on 100% similarity. Strains isolated from samples collected at the same production facility showed closer phylogenetic relation than those collected from distinct facilities. The result of extensive traceback sampling showed that PIF residues (PIF dust in production areas), fluid beds, drying areas, floors, and soil samples collected adjacent to the production facilities were the primary positive areas for Cronobacter. The present study outlines an effective approach to determine prevalence and genetic diversity of Cronobacter isolates associated with contamination of PIF.

Highlights

Cronobacter spp. belongs to the family Enterobacteriaceae, which were previously classified as Enterobacter sakazakii, consisting of C. sakazakii, C. malonaticus, C. turicensis, C. muytjensii, C. condimenti, C. universalis, and C. dublinensis (Stephan et al, 2014)
In Factory A, 10 C. sakazakii isolates were associated with samples collected from inside and immediately outside the factory, two C. turicensis and one C. sakazakii were recovered from samples collected from a water tank and air conditioner
Cronobacter spp. are opportunistic foodborne pathogens that can cause severe infections in neonates and infants through the ingestion of contaminated powdered infant formula (PIF); they are of global interest to human health (Forsythe et al, 2014; Fei et al, 2018a; Li et al, 2019)

Summary

Introduction

Cronobacter spp. belongs to the family Enterobacteriaceae, which were previously classified as Enterobacter sakazakii, consisting of C. sakazakii, C. malonaticus, C. turicensis, C. muytjensii, C. condimenti, C. universalis, and C. dublinensis (Stephan et al, 2014). Powdered infant formula (PIF) is a major vehicle for Cronobacter infections in neonates (Stephan et al, 2011; Hunter and Bean, 2013). A plethora of studies have shown that Cronobacter spp. can be isolated from PIF and PIF manufacturing facilities (Iversen et al, 2009; Craven et al, 2010; Fei et al, 2018b). Mullane et al (2007) profiled Cronobacter spp. isolates by pulsed-field gel electrophoresis (PFGE) from a PIF production site and demonstrated the persistence of specific bacterial clones in the production facility. Proudy et al (2008) highlighted that the environment is the major source of Cronobacter contamination of PIF and PIF production facilities. In depth studies focused on sources of Cronobacter within production environments are limited; most sampling is conducted on finished products

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