Prevalence, Molecular Characterization, and Antibiotic Susceptibility of Cronobacter sakazakii Isolates from Powdered Infant Formula Collected from Chinese Retail Markets.

Peng Fei,Yichao Jiang,Yan Jiang,Xiujuan Yuan,Stephen J Forsythe,Junliang Chen,Huaibin Kang,Ziyuan Wang,Tongxiang Yang

doi:10.3389/fmicb.2017.02026

Abstract

Cronobacter sakazakii is an opportunistic pathogen that causes severe infections in neonates and infants through contaminated powdered infant formula (PIF). Therefore, the aim of this study was a large-scale study on determine the prevalence, molecular characterization and antibiotic susceptibility of C. sakazakii isolates from PIF purchased from Chinese retail markets. Two thousand and twenty PIF samples were collected from different institutions. Fifty-six C. sakazakii strains were isolated, and identified using fusA sequencing analysis, giving a contamination rate of 2.8%. Multilocus sequence typing (MLST) was more discriminatory than other genotyping methods. The C. sakazakii isolates were divided into 14 sequence types (STs) by MLST, compared with only seven clusters by ompA and rpoB sequence analysis, and four C. sakazakii serotypes by PCR-based O-antigen serotyping. C. sakazakii ST4 (19/56, 33.9%), ST1 (12/56, 21.4%), and ST64 (11/56, 16.1%) were the dominant sequence types isolated. C. sakazakii serotype O2 (34/56, 60.7%) was the primary serotype, along with ompA6 and rpoB1 as the main allele profiles, respectively. Antibiotic susceptibility testing indicated that all C. sakazakii isolates were susceptible to ampicillin-sulbactam, cefotaxime, ciprofloxacin, meropenem, tetracycline, piperacillin-tazobactam, and trimethoprim-sulfamethoxazole. The majority of C. sakazakii strains were susceptible to chloramphenicol and gentamicin (87.5 and 92.9%, respectively). In contrast, 55.4% C. sakazakii strains were resistant to cephalothin. In conclusion, this large-scale study revealed the prevalence and characteristics of C. sakazakii from PIF in Chinese retail markets, demonstrating a potential risk for neonates and infants, and provide a guided to effective control the contamination of C. sakazakii in production process.

Highlights

Cronobacter spp. are emerging foodborne opportunistic pathogens that can infect neonates and infants resulting in necrotizing enterocolitis, bacteremia, and meningitis, with a 40–80% mortality rate (Holy and Forsythe, 2014; Li et al, 2016)
The information of all 56 C. sakazakii strains were submitted to the Cronobacter PubMLST database with PubMLST IDs 2005 to 2060
C. sakazakii is the dominant species in Cronobacter spp. associated with the infection of newborns through contaminated powdered infant formula (PIF), the issue of PIF contamination by C. sakazakii is a matter of continuing concern

Summary

Introduction

Cronobacter spp. are emerging foodborne opportunistic pathogens that can infect neonates and infants resulting in necrotizing enterocolitis, bacteremia, and meningitis, with a 40–80% mortality rate (Holy and Forsythe, 2014; Li et al, 2016) These organisms have be isolated from various food sources, including spiced meat, ready-to-eat foods, dehydrated rice powder, retail foods, and powdered infant formula (PIF) (Iversen and Forsythe, 2004; Hochel et al, 2012; Joseph et al, 2012a; Huang et al, 2015; Xu et al, 2015; Zhang et al, 2016; Brandão et al, 2017). The presence of C. sakazakii in commercial PIF needs to be monitored

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