Other Gram- Rods-Vishy

Question 1

What are the two types of Haemaphilus Influenza? What do they cause?

Answer 1

1. Encapsulated strains-cause invasive diseases like meningitis and sepsis and are hypervirulent.
   • Type B strain is the worst and has a polyribosyl phosphate capsule.
   • Symptoms for meningitis: headache, stiffness, fever and drowsiness
2. Non-encapsulated strains-cause upper respiratory tract infections like otitis media and sinusitis.
   • Symptoms for sinusitis and otitis media: pain in the affected area, opacification of sinus, swelling and redness of tympanic membrane

Question 2

What are the growth requirements for Haemaphilus Influenza? How is it transmitted? What are its virulence factors (3)? Who is most susceptible? Treatment? Prevention?

Answer 2

Grown in chocolate agar media with factor V (NAD) and factor X (heme compound).
Transmission thru respiratory droplets.
Virulent factors:
1. IgA protease.
2. Capsule.
3. Endotoxin (LPS)
More common among children 6 months – 1 year
Can also cause pneumonia in adults w/ chronic obstructive lung disease.
Treatment: PCN and chloramphenicol-resistant. Treat w/ Cefotaxime (3rd generation cephalosporin) and Rifampin prophylaxis in appropriate settings.
Prevention: Vaccine: influenza capsular polysaccharide conjugated to protein.

Question 3

What does Bordetella pertussis cause? Does it have a capsule? How is it transmitted? What causes tissues damage? What are its virulence factors (4)?

Answer 3

Causes “Whooping cough.”
Encapsulated but non-invasive.
Transmission thru respiratory droplets.
Toxins cause local tissue damage, destroying ciliated epithelial cells.
Virulence factors:
1. Filamentous hemagglutinin: helps bind bacteria to the ciliated epithelial cells.
2. Pertusis toxin: induces ADP-ribosylation of inhibitory subunit of G protein leading to activation of adenyl cyclase → increase in cAMP → activation of cAMP dependent protein kinase → mucous production and lymphocytosis.
3. Adenylate cyclase toxin: inhibits antimicrobial mechanisms in the macrophage.
4. Cytotoxin: combination of LPS and peptidoglycan → induces NO → destroys ciliated epithelial cells.

Question 4

What are the symptoms of bordetella pertussis infection? Diagnosis/culture media? Treatment? Prevention?

Answer 4

Symptoms: Incubation stage (fever and cough), catarrhal stage (fever, sneezing and anorexia), Paroxysmal stage (characteristic inspiratory gasp) and Convalescent stage (pneumonia and seizures).
Diagnosis: Cultured in Bordet-Gengou media.
Treatment: Erythromycin
Prevention: Vaccine: administered in boosters (birth, 1, 5 and 18 years old)

Question 5

What does Legionella cause? What are the sources? Transmission? Pathogenesis? Diagnosis/culture media? Treatment? Prevention?

Answer 5

Causes atypical pneumonia.
Sources: Moist areas like showers, whirlpools, humidifiers, AC, etc.
Transmission: respiratory droplets.
Mostly opportunistic organism.
Pathogenesis: Macrophages phagocytose the bacteria in the lungs. It recruits ribosomes onto the endosome/phagosome which tricks the cell into thinking it’s the ER and there is no release of lysozyme.
Diagnosis: Grown in charcoal-yeast media w/ Fe and cysteine.
Treatment: Erythromycin or fluoroquinolones.
Prevention: No vaccines. Don’t drink, don’t smoke, heat the water supply, and chlorinate the water.

Question 6

What does Brucella cause? Does it have a capsule? Is it motile? What are the 3 species and what is their reservoir? Transmission?

Answer 6

Causes brucellosis (undulant fever)
No capsules.
Non-motile.
3 species:
1. B. abortus (Reservoir: cattle)
2. B. suis (Reservoir: swine.)
3. B. melitensis (Reservoir: goats and sheep.)
*More virulent.
Infection thru contaminated meat or milk.

Question 7

What are the virulence factors for Brucella (2)? Pathogenesis? Symptoms? Diagnosis/culture media? Treatment? Prevention?

Answer 7

Virulence factors:
1. Endotoxin (LPS)
2. Cell wall Ag’s (A and M)
Pathogenesis: Hang out in the liver, spleen and lymph nodes. Form granuloma.
Symptoms: undulating fever = rise in temp during the day and fall at night.
Diagnosis: Grown in “blood broth.”
Treatment: Rifampicin + tetracycline for several months.
Prevention: Quarantine and vaccinate animals and don’t eat bad meat.

Question 8

What does Francisella tularensis cause? What is its reservoir? Transmission? Virulence factors (3)? Symptoms? Diagnosis? Treatment? Prevention?

Answer 8

Causes ulcero-glandular disease.
Present in dear, rabbits and some rodents.
Transmitted from animals to humans by tick (Dermocenter).
Virulent factors:
1. Capsule
2. LPS
3. Antiphagoctyic cell wall components.
Symptoms: Swelling of lymph nodes, ulcers, GI disease.
Diagnosis: Serology and fluorescent Ab.
Treatment: Streptomycin or tetracycline.
Prevention: Wear gloves and cook meat.

Question 9

What does Yersinia pestis cause? Does it have a capsule? What do they look like in stain? What are the different types of plague?

Answer 9

Causes Bubonic plague → pneumonic phage: swollen lymph nodes → lungs
Encapsulated bacteria. Without capsule = arrivulent.
Bacteria exhibit bipolar stain (resembles a safety pin).
1. Sylvanic plague-Transmission among dogs and rodents in the woods/forests.
2. Urban plague-Transmission in urban rats due to lack of sanitation.
3. Fleas are also reservoirs-Bacteria produce coagulase → causes thrombin production.

Question 10

What are the virulence factors for Yersinia pestis (4)? Diagnosis? Treatment? Prevention?

Answer 10

Virulence factors:
1. LPS
2. Capsule
3. VW antigen: prevents intracellular destruction in macrophages.
4. YOP: Yersinia outer protein inoculated into host cell by Type III secretion system, inhibiting signaling pathways of the host.
Diagnosis: Do smear and see bipolar stain (similar to safety pin).
Treatment: Streptomycin and Tetracycline. Treat in isolation room.
Prevention: Thru vector control (the fleas and rats).
Formalin-killed bacillus vaccine: good against bubonic plague but NOT pneumonic.