Intracellular Bacteria

Question 1

How do bacteria get inside cells?

Answer 1

• escaping the endo/phagosome
• preventing fusion with lysosomes
• surviving the phagokysosome

Question 2

What are actin rockets?

Answer 2

where some bacteria can hijack host cytoskeletal proteins to create polymerized actin tails

Question 3

What are the characteristics of mycobacterium species?

Answer 3

• acid fast stain
• aerobic gram + rods
• distinct cell wall: contains mycolic acid -> waxy, protective coating

Question 4

What are the characteristics of mycobacterium tuberculosis?

Answer 4

• respiratory/aerosol transmission
• bacteria grow & divide within inactivated pulmonary alveolar macrophages-> infects cells of reticuloendothelial system
• mount effective & rapid activated macrophage/T cell response

Question 5

What is the mycobacterium tuberculosis pathogenesis of immunocompetent?

Answer 5

• strong T cell response
• no appreciable lung damage
• activated macrophages & T cells wall off -> forms granuloma called tubercle

Question 6

What is the mycobacterium tuberculosis pathogenesis of immunocompromised?

Answer 6

• poor T cell response
• fever, coughing, bloody septum
• weight loss, loss of energy
• progressive lung damage
• bacteria escapes lungs -> systemic

Question 7

How is M. tuberculosis diagnosed?

Answer 7

• chest X-ray
• acid fast stain
• TB skin test -> injection of purified protein derivative; monitor for a type 4 hypersensitivity that only occurs if there is previous exposure to TB

Question 8

What are the steps of a TB skin test?

Answer 8

1. PPD Injected & phagocytized by APC’s
2. PPD antigen is processed and presented to CD4+ T Helper Cells
3. T Cells recognize antigen and release cytokines, IFN gamma, and other chemotactic factors
4. Monocytes migrate to injection site causing erythema/induration 24-48 hours later.
5. IFN Gamma activates monocytes to enhance killing of M. tuberculosis

Question 9

What is the prevention & treatment for M. tuberculosis?

Answer 9

• prevention: BCG vaccine
• treatment: antibiotics effective except for:
• DR TB -> multidrug resistant
• XDR TB -> extensively drug resistant
• CDR TB -> completely resistant

Question 10

What are the characteristics of bartonella henselae?

Answer 10

• slow growing gram - rod
• autoadherent: forms clumps & appears ‘rough’
• nonadherent: single bacteria & appears ‘smooth’

Question 11

What are the diseases of B. henselae?

Answer 11

1. cat scratch disease:
   - symptom: lymphadenopathy
   - associated with immunocompetent
2. bacillary angiomatosis:
   - prolfieration of vascular endothelium
   - associated with immunocompromised

Question 12

What are the virulence factors of B. henselae?

Answer 12

• badA: major adhesin promotes release of VEGF
• type 3 secretion system (VirB)
• beps: effector protein delivered by VirB

Question 13

What is the prevention & treatment of B. henselae?

Answer 13

• prevention: no vaccine; limit exposure to cats for immunocompromised
• treatment: azithromycin & doxycycline

Question 14

What are the characteristics of Rickettsia rickettsii?

Answer 14

• gram - pleomorphic rods
• animal reservoir, arthropod vector
• tick bite allows bacteria to enter blood stream & spread

Question 15

What are the symptoms & treatment of rocky mountain fever?

Answer 15

• symptoms: fever, tick bite, & rash
• treatment: tetracyclines

Question 16

What are the transmission, symptoms, & treatment of ehrlichia chaffeensis?

Answer 16

• transmission: vector -> amblyomma species
• symptoms: similar to rockymountain but NO RASH
• treatment: tetracyclines

Question 17

What are the characteristics of chlamydia trachomatis?

Answer 17

• small, gram -, pleomorphic
• NO peptidoglycan
• elementary bodies -> infection
• reticular bodies -> replication

Question 18

Where can C. trachomatic occur?

Answer 18

• respiratory tract
• ocular -> conjunctivitis & trachoma
• genital tract -> lymphogranuloma venereum