CORYNEBACTERIUM IMITANS SP-NOV ISOLATED FROM PATIENTS WITH SUSPECTED DIPHTHERIA

A 5-month-old boy of a Romanian family traveling via Ukraine to Poland developed a respiratory disease that resembled and that was initially diagnosed as pharyngeal diphtheria. The child recovered after treatme nt with antidiphtheria antitoxin. A coryneform bacterium had been isol ated from a nasopharyngeal specimen from the child and was initially i dentified as an atypical Corynebacterium diphtheriae strain, Seven adu lts who had contact with either the child or an adult contact person a lso developed symptoms of pharyngeal diphtheria, were also treated wit h antitoxin, and recovered uneventfully. Coryneform bacteria similar t o that originating from the index patient were also isolated from the throat swabs of three adults, Detailed biochemical and chemotaxonomic investigations revealed that the coryneform bacteria belonged to the g enus Corynebacterium and could be differentiated from all other define d species of this genus. Ribotyping and pulsed-field gel electrophores is demonstrated that dl four patients' isolates were of clonal origin. The diphtheria toxin gene and its product were not detected either by PCR assays or by the Elek test, making a possible disease association of the Corynebacterium more unlikely. Comparative 16S rRNA gene seque nce analysis revealed that the coryneform bacterium represented a new subline within the genus Corynebacterium, for which the name Corynebac terium imitans sp. nov. is proposed, The type strain is NCTC 13015 (DS M 44264; CCUG 36877).