Bacteriology - Rickettsia

Front 1

Rickettsia; general characteristics:
a. size
b. gram-staining
c. energy
d. transmission

Back 1

a. small
b. gram-negative, but poor staining - may need giemsa stain
c. obligate intracellular, although has independent metaolic pathway to make ATP, but it still prefers to hi-jack and steal from host
d. arthropods --> human

Front 2

Four main bugs that can transmit Rickettsia:

Back 2

1.tick
2. louse
3. mite
4. flea

Front 3

R. ricketsii causes which disease?

Back 3

Rocky Mountain Spotted Fever

Front 4

R. akari causes which disease?

Back 4

Rickettsial pox

Front 5

What is different between Rickettsia and Chlamydia when they enter the cell?

Back 5

In chlamydia, they enter and inhibit formation of phagosome. Rickettsia doesn't inhibit the formation, but can escape after the phagosome is formed.

Front 6

Rickettsia pathogenesis:

Back 6

No known toxin
Infects endothelium of small blood vessels and destroys them. This causes leakage of blood (we'll see a rash), and organ/tissue damage.

Front 7

What is the vector in Rocky Mountain Spotted Fever?

Back 7

Hard tick; 6-24 hours attachment required prior to bacteria inoculation via their saliva. This is because the load of bacteria within the saliva is low, so it needs to inject quite a lot of saliva to reach the infective dose. Problem is that the saliva of tick has anesthetic, so we don't feel it.

Front 8

RMSF clinical manifestations:

Back 8

2-12 days incubation
abrupt onset of fever, chills, headache, myalgia
rash on palms of hands, soles of feet, and trunk
Other forms of rickettsia don't cause rash on palms and soles, so this is a good indication of R. rickettsii.

Front 9

If RMSF isn't treated, what can happen?

Back 9

The bacteria will propagate, destroying more blood vessels, ultimately reaching point of cardiac failure, GI, renal, and respiratory tract problems.

Front 10

Why is the rash caused by RMSF a good thing?

Back 10

Allows proper diagnosis and timely treatment. Without rash, prognosis is usually very poor.

Front 11

RMSF diagnosis

Back 11

Clinical tests and patient history
Lab tests: Today we use PCR and
specific serological tests

Front 12

RMSF treatment and prevention

Back 12

Tetracycline, chloramphenicol
No vaccine
Prevention of tick bites!

Front 13

Rickettsial pox caused by R. akari
-vector
-disease and symptoms
-treatment

Back 13

vector: mite
disease and symptoms: one week incubation, will see papula at site of bite, onset of FCHM, and generalized rash. disease is usually mild.
treatment: tetracycline, chloramphenicol

Front 14

Rickettsia Prowazeki causes:

Back 14

Typhus

Front 15

Reckettsia Prowazeki vector and reservoir:

Back 15

vector: louse via their feces! ew.
reservoir: humans - associated with unsanitary conditions

Front 16

Rickettsia Prowazeki
-incubation
-clinical manifestations
-complications

Back 16

Incubation: 1 week
Symptoms: FCHM, maculopapular rash from trunk to extremities
Complications: myocarditis, stupor, delirium
difficult recovery and high mortality

Front 17

Rickettsia Prowazeki
-diagnosis
-treatment

Back 17

diagnosis: serology
treatment: tetracycline and chloramphenicol

Front 18

Rickettsia Typhi
-vector
-reservoir

Back 18

vector: rat flea
reservoir: rat

Front 19

Rickettsia Typhi
-clinical manifestations
-treatment

Back 19

Disease: Endemic Typhus
Incubation is one week, then FCHM followed by maculopapular rash from trunk to extremities. mild disease; often resolves itself
Treatment: tetracycline, cloramphenicol

Front 20

Rickettsia Tsutsugamushi
-vector
-reservoir

Back 20

vector: mite larvae (chiggers)
reservoir: chiggers and rats

Front 21

Rickettsia Tsutsugamushi
-clinical manifestations
-treatment

Back 21

Disease: Scrub Typhus (asia)
Incubation of 1-3 weeks, then FCHM followed by maculopapular rash from trunk to extremities. Disease severity is variable.
Treatment: tetracycline, chloramphenicol