Question

what is this organism?

Long ago, people thought that I was a virus but I am small bacterium. Although I can't be stained by Gram stain, I am considered as Gram negative. I always live inside host cell and all attempts to grow me on artificial culture media have been failures. I can be grown on egg yolk and cell culture. When I grow inside the host cell, I am seen as inclusion body. I can spread through direct contact including a sexual route. I cause ocular and genital infections in humans. I am susceptible to tetracycline and macrolides.

Answer 1

Chlamydia trachomatis is the bacterium which matches the following characteristics. It was once mistaken to be a virus because of it's very small size, when viruses were filtered from bacteria, chlamydia also passed through the filter along with the viruses and its dependence on the biosynthetic machinery of host as it is an obligate intracellular parasite of eukaryotic cells but after checking its life cycle and body organisation it resembles the bacterium.Chlamydia trachomatis contains RNA/DNA as their genetic material just like viruses but has a cell wall, so was considered as a bacterium. It causes STI and spreads through vaginal, anal and oral routes. These are gram negative bacteria which are obligate intracellular parasite means their metabolism is activated only when are inside a host. The infectious elementary body is metabolically inactive so, are not sensitive to all antibiotics. Only those antibiotics which can invade the cells are effective against Chlamydia trachomatis like tetracycline and macrolides which penetrates the cell and stops the protein synthesis.