Molecular characterization of Cronobacter sakazakii isolated from different herbal teas and mixtures in Serbia

Abstract

Cronobacter sakazakii is an important cause of human infections that can be serious and even fatal among premature neonates and immunocompromised adults or infants. Because of its high tolerance to osmotic stress, C. sakazakii is frequently isolated from dried foods, such as powdered infant formula and herbal teas. The aim of investigation was detection, identification and molecular characterization of Cronobacter sakazakii isolates from infant formula and various herbal teas collected from Serbian market and tested for import control. C. sakazakii was not detected in any of the 360 analysed samples of powdered infant formula. However, 192 out of 520 samples of herbal teas tested were positive for C. sakazakii (37.1%). The high prevalence was observed in teas for children (51.6%) and in "baby" teas (44.1%), followed by medicinal teas (38%). The largest one-herb-teas group (221 samples) contained 72 C. sakazakii-positive samples (32.6%) and involved Sennae folium, Althaeae radix, Menthae piperitae folium, Chamomilae flos and Urticae folium teas. Molecular characterization of isolated C. sakazakii from different herbal teas by rep-PCR, RAPD and 16S rRNA sequences analysis showed the high similarity to C. sakazakii NCTC 8155. Knowing this strain as one of the most pathogenic clinical strains, our results raise concern about the safety risks these foods pose to immunocompromised and healthy consumers, especially for babies and children.