TREPONEMA PALLIDUM

Treponema Pallidum

Treponema Pallidum

Treponema pallidum is causative agent of syphilis, the sexually transmitted disease (STD). Other bacteria in same genus cause diseases yaws and bejel, which are transmitted through direct skin-to-skin contact or sharing of drinking vessels. T. pallidum has the characteristic helical shape, and is the member of Spirochete family of bacteria (Fraser 1998). However, not all helical bacteria are Spirochetes:

Spirilla, majority of which are saprophytes

Spiroplasma, including mycoplasmas

Vibrio, Campylobacter and Helicobacter

Spirochetes, the group of five genera, very widespread in nature and found in fresh waters, of which only first three are pathogenic for humans:

Treponema

Borrelia

Leptospira

Spirocheta

Cristispira

Spirochetes are simple bacteria, with less than 1000 genes. Each type has the characteristic helical shape. Some are tightly coiled like the telephone cord, while others are more open (Fraser 1998). Very tight coils are seen in Leptospira, medium coils in Treponema and open coils are seen in Borrelia. Spirochetes are Gram-negative and with the flagellar bundle running through their periplasmic space. spirochete flagella run in perplasmic space, causing cells to move in the corkscrew fashion. 

Syphilis is spread by mostly by sexual contact, except for congenital syphilis, which is spread from mother to fetus. Transmission by sexual contact requires exposure to moist lesions of skin or mucous membranes. As with many STDs, sexual promiscuity has resulted in an increase in syphilis during last few decades. symptoms of syphilis occur in three stages called primary, secondary and late (Fraser 1998):

first sign of syphilis is the lesion known as the "chancre" (the clean, painless, indurated ulcer) which forms at site of entry where organism enters body through mucous membranes or breaks in epithelium. Multiple chancres occur if more than one organism enters. chancre lesions contain an initially local infection by Treponeme. Common sites for lesions include genitalia, rectum, urethra and mouth. chancre, which may be accompanied by ...