Rickettsia, Chlamydia and Mycoplasma MCQs

RBs are also the metabolically active form and can synthesize their own nucleic acid, lipids and proteins except ATP; hence, they are called as energy parasites (as they depend on host ATP for survival). Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 766

C. psittaci: Forms diffuse vacuolated inclusions without glycogen matrix. Resistant to sulfonamide. Natural pathogen of birds. Leaves the host cell by lysis. Has many serotypes. Disease caused by it: Psittacosis (Atypical interstitial pneumonia). Transmission is by inhalation route - pet birds (parrots) and poultry (turkeys and ducks) No man-to-man transmission. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 767

C. pneumoniae - TWAR agent Exclusive human pathogen Forms inclusions without glycogen matrix Resistant to sulfonamide Has Only 1 serotype Causes: Community-acquired atypical pneumonia. Associated with: atherosclerosis and asthma. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 767

Pre-treatment of cell lines with diethylaminoethanol (DEAE) dextran or centrifugation after inoculation of specimen should be done to promote contact between chlamydiae and the cells, thus increasing the chance of isolation. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 769

Mycoplasma bacteria lack cell wall. The cell wall acting agents like Beta-lactam antibiotics are ineffective against it. Reference: Ananthanarayan and Paniker's Textbook of Microbiology 10th edition Chapter 2, Pg 10

Chlamydiae were once thought to be viruses because of possessing a few viral properties, such as: They are obligate intracellular. They cannot be grown in artificial media. Filterable - small enough to pass through bacterial filters. Produce intracytoplasmic inclusions. However, chlamydiae are now confirmed to be bacteria, because they have many other properties similar to that of bacteria, as follows: Possess both DNA and RNA. Their cell wall is similar to that of gram-negative bacteria (although they lack peptidoglycan layer). Multiply by binary fission. Susceptible to a wide range of antibacterial agents. Reference: Essentials of Medical Microbiology, by Apurba Sastry and Sandhya Bhat, 3rd edition, page no: 766

Ans. is 'a' i.e., Rickettessiae prowazki & Louse

Ans. is 'b' i.e., Leptotrombidium deliense o For scrub typhus :- Causative agent R. tsutsugamushi Vector trombiculid mite (Leptotrombidium delinese and L. akamushi)