Scientific journal

54 2015

Journal of Food and Nutrition Research
Summary No. 2 / 2015

Kajsík, M. – Krahulec, J. – Tóth, C. – Drahovská, H. – Stuchlík, S. – Turňa, J.
Control of Cronobacter in reconstituded infant formula by combined application of cathelicidin LL-37 and bacteriophages
Journal of Food and Nutrition Research, 54, 2015, No. 2, s. 122-127

Hana Drahovska, Department of Molecular Biology, Faculty of Natural Sciences, Comenius University, Mlynska dolina 1, 842 15 Bratislava, Slovakia. E-mail:

Received 2 October 2014; revised 17 October 2014; accepted 22 October 2014; published online 31 March 2015

Summary: Cronobacter spp. is responsible for rare but fatal cases of infections in neonates and immunocompromised infants. The reconstituded powdered infant formula (PIF) is one of main sources of newborn infections. The aim of our study was to assess application of recombinant human cathelicidin LL-37, an antimicrobial peptide, alone and in combination with bacteriophages against Cronobacter in PIF. The minimal inhibitory concentration (MIC) of LL-37 determined by radial diffusion method for ten representative Cronobacter strains ranged from 2.56 µg·ml-1 to 8.83 µg·ml-1, and the values were below MIC of E. coli standard strain. By testing the antimicrobial activity in liquid growth medium, substantial inhibition of strains was observed at 30 µg·ml-1 LL-37, whereas 20 µg·ml-1 showed only moderate effect. However, higher peptide concentrations were necessary to inhibit Cronobacter in reconstituted PIF. By using 50 µg·ml-1 and 100 µg·ml-1 LL-37, numbers of cells decreased after 4-hour cultivation by approx. 70% and 96%, respectively. Finally, simultaneous application of LL-37 and bacteriophage Dev-CS-701 resulted in synergistic effect, as a 1 300-fold reduction of cell numbers in PIF was observed. Application of the two antimicrobial agents thus facilitated their reduced dosing and decreased the probability of generation of phage-resistant cells.

Keywords: Cronobacter, cathelicidin, bacteriophages, powdered infant formula

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