2 English reference KLB
Note: Corynebacterium diphtheriae, also known as KLB, is the pathogen of human diphtheria. The cell size is (0.3 ~ 0.8) × (1 ~ 8) micron, with obvious metachromatic granules and no optical power. The optimum temperature is 37℃, and it can grow on common culture medium, but its shape is not typical. It grows rapidly on Levreux coagulated serum or egg medium, with typical morphology, especially in metachromatic granules. Corynebacterium diphtheriae colony is black on blood agar medium containing 0.04% potassium tellurite. According to the characteristics of colony on potassium tellurite medium and biochemical reaction, it can be divided into heavy, light and intermediate types, and type 3 virulent strain has pathogenic effect on human beings. It is sensitive to heat or common disinfectants, and has stronger resistance to dryness, cold and sunlight than ordinary non-spore bacteria. It is still contagious if it is left on children's toys and daily necessities for a few days.
Exotoxin is the main pathogenic substance, and only strains carrying β -phage will produce exotoxin. Bacteria usually grow and reproduce on the throat mucosa and secrete exotoxin, which can cause local inflammation and form a gray-white false membrane. Exotoxin entering the blood causes systemic poisoning symptoms, interferes with the protein synthesis of host susceptible cells, and often damages myocardium and peripheral nerves. After illness, the body produces antitoxin antibodies and has strong immunity. Patients can be treated with diphtheria antitoxin and penicillin.
There are also some bacteria whose biological characteristics are similar to diphtheria, which are called Corynebacterium diphtheriae. It often exists in the nasal cavity, throat, external auditory canal, conjunctiva, vulva and skin surface of human or animals. Most of them are not pathogenic to people, and some may be conditional pathogens. Others are pathogenic to animals.