A study of the isolation of Corynebacterium diphtheria from clinical cases of diphtheria

Throat swabs from 1000 clinical cases of diphtheria were studied for isolation of C. diphtheria; only 21.4% were found to be positive. Most of the cases were between 1 to 4 years of age followed by 5 to 8 years. No cases were found below 8 months of age. The throat swabs taken from another 22 clinical diphtheria patients were immediately cultured at patients bed side and 63.6% were found to be positive for C. diphtheria. Time between the collection and plating the specimen was considered to be one of the main factors in the variation of the percentage isolation of C. diphtheria. From all KLB positive cases on direct smear, C. diphtheria could not be isolated on culture. Also, from all cases having definite patch(es) over tonsil(s), C. diphtheria could not be isolated. All strains were found to be sensitive against commonly used antibiotics.