Micro 3- atypical bacteria

Question 1

mycoplasmatales

Answer 1

• lack a cell wall, pleomorphic
• small, 200-250nm, can pass through filters
• may demonstrate filamentous growth
• colonies have a “fried egG” apperance
• mycoplasma pneumoniae causes mild pneumonia

Question 2

clamydiae

Answer 2

• gram negative coccoid bacteria
• obligate intracellular parasites
• no peptidoglycan in cell wall, grow intracellularly within host cell
• size of 200-300nm
• infective agent is the elementary body
• transmitted by interpersonal contact or airborne
• does NOT require insects or ticks for transmission

Question 3

examples of clamydiae

Answer 3

1. chlamydia trachomatis causes trachoma dna nongonococcal urethritis
2. chlamydophila psittaci causes respiratory psittacosis (ornithosis)
3. chlamydophila pneumoniae causes mild form of pneumonia in young adults

Question 4

rickettsia

Answer 4

• gram negative rod-shaped or coccobacilli
• obligate intracellular parasites
• 300-1000nm size
• transmitted via insects or tick bites
• enter host cell by inducing phagocytosis
• damage permeability of blood capillaries and result in spotted rash

Question 5

examples of rickettsia

Answer 5

(Causes spotted fevers)

1. R. prowazekii: epidemic typhus transmitted by lice
2. R. typhi: endemic murine typhus transmitted by rat fleas
3. R. rickettsii: Rocky Mountain spotted fever, transmitted by ticks