This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Microbiology
[{'content': 'The following statements are true regarding Chlamydia except: \nSelect and explain. \nA. Erthromycin is effective for therapy of Chamydial infections, B. Their cell wall lacks a peptidoglycan layer, C. They can grow in cell free culture media, D. They are obligate intracellular bacteria', 'role': 'user'}, {'content': "Answer: C \nExplanation: Unique properties of Chlamydia are\nChlamydia is an obligate intracellular parasite. This means they can survive only by establishing residence inside\nAnimal cells\nThey need their host's ATP as an energy source for their own cellular activity. They are energy parasites using a\nCell membrane transport system that uses ATP from the host system and gives out ADP.\nThis obligate intracellular existence makes it impossible to culture these organisms on nonliving artibacterial media.\nDue to their small size and failure to grow in cell - free media they were considered to be viruses.\nChlamydiae grows in cultures of a variety of eukaryotic cell lines Me Coy or HeLa cells. It may be necessary to\nTreat cells with poly anionic compounds such as DEAD-dextran to reduce the electrostatic barrier to infection.\nAntimetabolite such as cycloheximide is added to favour competition for host cell amino acid pools. All types of\nChlamydiae proliferate in embryonated eggs particularly in the yolk sac.\nThe special features in structure and chemical composition of chlamydiae are\nThe outer cell wall resembles the cell wall of gram negative bacteria It has a relatively high lipid content\nIt is rigid but it does not contain typical bacterial peptidoglycan; perhaps it contains a Tetrapeptide linked matrix.\nN Acetyl muramic acid also appears to be absent from chlamydiae cell wall\nAntibiotic susceptibility of chlamydiae.\nPenicillin binding proteins occur in chlamydiae cell wall and chlamydiae cell wall formation is inhibited by penicillins\nAnd other drugs that inhibit transpeptidation of bacterial peptidoglycan. But remember the important point about t/t,\nThat cell wall inhibitors result in the production of morphologically defective forms but are not effective in clinical\nDisease.\n• Inhibitors of protein synthesis (tetracyclines, erythromycins) are effective in most clinical infections. Erythromycin\nOr tetracyclines are considered the drug of choice for chlamydiae infections.", 'role': 'assistant'}]