Antibiotic and Desiccation Resistance of Cronobacter sakazakii and C. malonaticus Isolates from Powdered Infant Formula and Processing Environments

Abstract

This study evaluated the antimicrobial and desiccation resistance of Cronobacter sakazakii and Cronobacter malonaticus isolates from powdered infant formula and processing environments. The antimicrobial susceptibility tests showed that the 70 Cronobacter strains, representing 19 sequence types, were susceptible to the most of the antibiotics except for amoxicillin-clavulanate, ampicillin, and cefazolin. Furthermore, the growth of six C. sakazakii and two C. malonaticus strains from different sequence types (STs) in hyperosmotic media was measured. The growth of the two C. sakazakii strains (CE1 and CE13) from the neonatal pathovars ST4 and ST8, were significantly higher (p < 0.05) than that of other strains. C. malonaticus strain CM35 (ST201) was the slowest grower in all strains, and most could not grow in more than 8% NaCl solution. Also the survival of these strains under desiccation conditions was followed for 1 year. The viable count of Cronobacter spp. under desiccation conditions was reduced on average by 3.02 log cycles during 1 year, with CE13 (ST8) being the most desiccation resistant strain. These results will improve our understanding of the persistence of the two closely related species C. sakazakii and C. malonaticus which are of concern for neonatal and adult health.

Survival of Cronobacter in powdered infant formula and their variation in biofilm formation

“…In contrast to these findings, Fei et al . () recently reported a higher resistance to osmotic stress for C. sakazakii compared with C. malonaticus , which may, in part, account for the predominance of C. sakazakii in PIF. Though C. sakazakii ST1 and ST4 are the dominant types in PIF production environments (Forsythe et al .…”

“…Fei et al . () observed that the viable count of Cronobacter sp. under desiccation conditions was reduced on average by about 1·55 log cycles in the first 60 days and by 3·02 log cycles after 1 year.…”

“…The ability of Cronobacter isolates of different STs to resist desiccation stress was also evaluated in the study by Fei et al . (), who identified an ST8 strain as the most resistant to such stress. Conversely, in the current study, an ST8 strain (05CHPL01) was very sensitive to desiccation.…”

Broad spectrum antibiotic-degrading metallo-β-lactamases are phylogenetically diverse and widespread in the environment

“…It was thus proposed that this B3 variant may represent a distinct subgroup of MBLs (33,37), for which we propose the abbreviated name B3-RQK based on its active site substitutions (see above). Although not recognized in the study, another B3-RQK MBL (CSR-1) was subsequently identified in an invasive foodborne pathogen, Cronobacter sakazakii (38). This organism can cause life-threatening meningitis, septicemia and necrotizing enterocolitis with a 95 40-80% mortality rate (38)(39)(40), and resistance to antibiotics amongst various Cronobacter strains has already been reported (38).…”

“…Although not recognized in the study, another B3-RQK MBL (CSR-1) was subsequently identified in an invasive foodborne pathogen, Cronobacter sakazakii (38). This organism can cause life-threatening meningitis, septicemia and necrotizing enterocolitis with a 95 40-80% mortality rate (38)(39)(40), and resistance to antibiotics amongst various Cronobacter strains has already been reported (38). Another B3 MBL (GOB-1) with a minor motif variant (QHH/DHH; B3-Q) was discovered in the opportunistic pathogen Elizabethkingia meningoseptica, which has broad spectrum activity against a range of β-lactam antibiotics, similar to native B3 MBLs such as AIM-1 (26,27).…”