Atypical Bacteria

Question 1

MYCOPLASMATACEAE

Answer 1

Smallest known free-living organisms: 0.15-0.3mm dia
LACK CELL WALL – entire life (stain pink – Gram’s)

Cytoplasmic membrane contains STEROLS

Resistant: penicillin, cycloserine & lysozyme

Reproduction: Cell elongates (filament), coccoid form from filament (Binary fission), released by fragmentation

Diphasic colonies (“fried egg”) on agar EXCEPT M. PNEUMONIA!!!

Adhesion: Tapered tip + P1 adhesin

Tissue Destruction via H2O2 & O2-

Question 2

RICKETTSIAECEAE

Answer 2

Obligate intracellular pathogen, not cultivated on agar, Zoonotic (spread via ticks, mites, fleas, lice)

CANT MAKE ATP
Closely related to Gram –ve
Rod/coccobacillary shaped (pleomorphic)

Question 3

ANAPLASMATACEAE & COXIELLA

Answer 3

OBLIGATE INTRACELLULAR PATHOGENS
Zoonotic
Small: 0.2-2mm

Question 4

CHLAMYDIACEAE

Answer 4

• Infect Man ONLY C. trachomatis
• Zoonotic infections (birds to man) C. pneumoniae, C. psittaci
• Non-motile, coccoid bacteria
• OBLIGATE INTRACELLULAR PATHOGENS
• DO NOT GENERATE ATP
• NO Peptidoglycan detected

Question 5

DEVELOPMENTAL FORMS OF CHLAMYDIACEAE

Answer 5

Elementary Body (EB): Non-replicating, infectious,
small, adapted for extracellular survival, induce endocytosis, metabolically inactive

Reticulate Body (RB)/(Initial Body, IB): Replicating, non-infectious, larger, adapted for intracellular growth, metabolically active

endocytosis -> cell wall -> reticular body -> maturation -> release of elementary bodies