Phenotypic, Molecular Identification and Virulence Assessment of Cronobacter spp Isolated from Clinical Samples of Children Under Two Years in Mosul City/Iraq

Abstract

Cronobacter spp. is known to be a foodborne causative agent for a variety of diseases in both humans and animals. This study focused on isolating Cronobacter species from 150 clinical samples of children under two years (60 from blood and stool samples, 30 from CSF samples) collected from Ibn al Atheer and Al Khanssa Hospitals. The phenotypic identification of bacterial isolates were performed through culture, microscopic, and biochemical examinations and vitek-2 system. The results revealed a mixture of bacteria in 6.5% of the clinical specimens. The identity of isolates was 99% using the vitek-2 system for identifying Cronobacter sakazakii, Cronobacter malonaticus, Cronobacter muytjensii, and Cronobacter pulveris. Out of 150 specimens there were 8 (5.33 %) of specimens gave positive for Cronobacter spp which included: C. sakazaki 2/60 blood specimens (3.3%), C. sakazaki 2/60 stool specimens (3.3%), C. malonaticus 2/60 stool specimens (3.3%), 1/60 C. muytjensii and C. pulveris 1/60 (3.3%). The eight isolates phenotypically identified as Cronobacter were confirmed at the molecular level through 16S rRNA sequencing and submitted to NCBI under the accession numbers (OR825874, OR825875, PP126443, PP126444, PP126445, PP126455). The virulence profile of these isolates showed that 7/8 (87.5%) of Cronobacter strains exhibited haemolysin activity, 5/8 strains (62.5%) were able to produce the protease enzyme and 2/8 (25%) of Cronobacter strains were positive for lipase and lecithinase. All strains lacked the ability to produce a slime layer. The results also showed the ability of Cronobacter strains to produce biofilm by using the tube method and microtiter plate method but with different levels.