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Published on: February 17, 2023
Emerging of Multidrug-Resistant Cronobacter sakazakii Isolated from Infant Supplementary Food in China
Xin Gan1, Menghan Li1, Jin Xu1
1Key Laboratory of Food Safety Risk Assessment, National Health Commission, China National Center for Food Safety Risk Assessmentgrid.464207.3, Beijing, People's Republic of China.
Insights
Two multidrug-resistant Cronobacter sakazakii strains were found in Chinese infant foods. Genomic analysis revealed these strains acquired antimicrobial resistance genes via horizontal gene transfer, highlighting the need for monitoring and control.
Area of Science:
- Food safety and microbiology
- Genomics and infectious diseases
- Antimicrobial resistance
Background:
- Cronobacter is a foodborne pathogen causing severe infections, particularly in neonates and infants.
- Multidrug-resistant (MDR) Cronobacter isolates are increasingly reported, posing a significant public health threat.
- Understanding the prevalence and genetic basis of MDR Cronobacter in infant foods is crucial for risk assessment.
Purpose of the Study:
- To investigate the prevalence and antimicrobial resistance (AMR) phenotype of Cronobacter in powdered infant formula and supplementary food in China.
- To characterize the virulence factors, AMR genes, and genomic environments of MDR Cronobacter isolates.
- To elucidate the mechanisms of AMR acquisition in food-associated Cronobacter.
Main Methods:
- Nationwide surveillance of Cronobacter in infant foods across 29 provinces in China (2018-2019).
- Antimicrobial susceptibility testing and identification of MDR isolates.
- Whole-genome sequencing and comparative genomic analysis of MDR Cronobacter sakazakii isolates.
Main Results:
- 1,055 Cronobacter isolates were recovered, with 11 (1.0%) exhibiting antimicrobial resistance.
- Two MDR Cronobacter sakazakii isolates (ST4 and ST40) were identified, resistant to four antimicrobials.
- Both MDR isolates harbored multiple virulence and AMR genes, with resistance determinants found on IncFIB plasmids.
Conclusions:
- Food-associated Cronobacter sakazakii can acquire antimicrobial resistance determinants through horizontal gene transfer (HGT).
- The identification of MDR C. sakazakii in infant foods underscores the importance of continuous monitoring.
- Implementing appropriate control measures is essential to reduce contamination and transmission of MDR Cronobacter in infant products.
Abstract:
Cronobacter is a foodborne pathogen associated with severe infections in restricted populations and particularly with high mortality in neonates and infants. The prevalence and antimicrobial resistance (AMR) phenotype of Cronobacter cultured from powdered infant formula and supplementary food were studied. The virulence factors, AMR genes, and genomic environments of the multidrug-resistant isolates were further studied. A total of 1,055 Cronobacter isolates were recovered from 12,105 samples of powdered infant formula and supplementary food collected from 29 provinces between 2018 and 2019 in China. Among these, 1,048 isolates were from infant supplementary food and 7 were from powdered infant formula. Regarding antimicrobial resistance susceptibility, 11 (1.0%) isolates were resistant and two showed resistance to four antimicrobials (ampicillin [AMP], tetracycline [TET], sulfamethoxazole-trimethoprim [SXT], and chloramphenicol [CHL]), defined as MDR. These two MDR isolates were subsequently identified as Cronobacter sakazakii sequence type 4 (ST4) (C. sakazakii Crono-589) and ST40 (C. sakazakii Crono-684). Both MDR isolates contain 11 types of virulence genes and 7 AMR genes on their genomes. Meanwhile, the IncFIB plasmids of both MDR C. sakazakii isolates also harbored 2 types of virulence genes. Results of the genomic comparative analysis indicated that food-associated C. sakazakii could acquire antimicrobial resistance determinants through horizontal gene transfer (HGT). IMPORTANCE As a foodborne pathogen, Cronobacter can cause serious infections in restricted populations and lead to death or chronic sequelae. Although a number of investigations showed that Cronobacter isolates are susceptible to most antimicrobial agents, MDR Cronobacter isolates, isolated mainly from clinical cases but occasionally from foods, have been reported in recent years. In this study, we successfully identified two MDR Cronobacter sakazakii isolates from infant foods based on nationwide surveillance and genome sequencing in China. Genomic analysis revealed that these two MDR C. sakazakii strains acquired resistance genes from other species via different evolution and transmission routes. It is important to monitor MDR C. sakazakii isolates in infant foods, and appropriate control measures should be taken to reduce the contamination with and transmission of this MDR bacterium.
