Unusual bugs

Question 1

Which of the following about Rickettsia is correct?
A. It is obligate intracellular like Chlamydia
B. It is a gram- bacilli
C. It does not stain in Gram stain because it is too small
D. Animals are their reservoir
E. Tick, louse, flea, and mites are examples or their anthropoid vectors

Answer 1

All of the above

Question 2

State the transmission method of Coxiella burnetti. (2)

Answer 2

1. Coxiella: spores survive in animal feces

2. Direct contact with farm animals/aerosol

Question 3

Rickettsia invades endothelial cells lining capillaries and cause _______________.

Answer 3

Diffuse vasculitis

Question 4

How are Rickettsia infections diagnosed? (3)

Answer 4

1. Complement fixation test
2. Antibody detection: immunofluorescence stain
3. Weil-Felix test: cross reaction (agglutination test) of Rickettsia Ag with OX strains of Proteus vulgaris (no longer used)

Question 5

What are the general clinical presentations of Rickettsia infected patients? (3)

Answer 5

General Triad of fever, rash, headache

Question 6

Rickettsia ricketsii contains OX2, 9 strains. It is tick-borne, and causes Rocky Mounter Spotted Fever which is characterized by?
- Prostration 1-2 week after tick bite, mortaility 90% if untreated

Answer 6

RMSF

1. Centripetal rash (benign peripherally on ankles and wrist > trunk)
2. Chills
3. Fever

Question 7

Name the types of bacteria under the Typhus group of Ricketssia. (3) State their respecitive vector.

Answer 7

1. Rickettsia prowazekii : louse-borne
2. Rickettsia typhi: flea-borne
3. Rickettsia tsutsugamushi: mite-borne

Question 8

List all the clinical prensention caused by Rickettsia prowazekii. (6)

Answer 8

1. Epidemic typhus (widespread)
2. Rash sparing the face, head and feet
3. Pneumonia
4. Encephalitis
5. Myalgia
6. Arthralgia (joint pain)

Question 9

What is Brill Zinsser disease?

• Weil-Felix test +/-?
• With/ without rash?

Answer 9

The recurrent form of typhus after years

• Weil-Felix test -ve
• without rash

Question 10

_____________ causes endemic typus. It contains OX19.

Answer 10

Rickettsia typhi

- edemic = localized

Question 11

Rickettsia tsutsugamushi (OXK) causes _________, clinical presentaions include fever, intense headache, wound that eventually develop into __________.

Answer 11

Scrub typhus;

eschar

Question 12

Other than the Spotted fever group and Typus group, name the other group of Rickettsia and the bacteria that belongs it this group.

Answer 12

Q fever group

- Coxiella burnetti

Question 13

How is Coxiella burnetti transmitted?

How is it diagnosied?

Answer 13

Inhaltion, extremely low infectious dose, 1-10 bacteria

Diagnosed by serology: complement fixation test

Question 14

Which of the following about the clinical presentations of Coxiella burnetti infection are correct? (Q fever)

A. Rash
B. Fever
C. Flu-like illness
D. Atypical pneumonia
E. Hepatitis 
F. Endocarditis

Answer 14

All except A

Endocarditis is rare and chronic, in immunocompromised patients

Question 15

What is the treatment of Ricketssia infections?

How about for Q fever endocarditis?

Answer 15

• Doxycycline x2/52

- Q fever endocarditis: Doxycycline + hydroxychloroquine x 18m

Question 16

List the hallmarks of Chronic Q infection. (5) (hallmark usually hits one only?)

Answer 16

1. Culture negative endocarditis (60-70% of chronic Q)
2. Intravascular infections (mycotic aneurysm, vascular graft infection)
3. Chronic granulomatous hepatitis (Doughnut granulomata or fibrinous ring granuloma)
4. Osteoarticular infections
5. Abortion, stillbirth

Question 17

Name the 3 types of Spirochetes that you have learnt.

Answer 17

1. Treponema pallidum
2. Borrelia burgdorferi
3. Leptospira interrogans

Question 18

What does the name Spirochetes suggest of the bacteriae?
It is too thin to be visualised by ordinary light mircroscopy, but is visualized in dark microscopy. What is the shape of Leptospira interrogans?

Answer 18

Spiral G- rods;

Leptospira with a question mark shape

Question 19

What are the 2 modes of transmission of Treponema pallidum?

Answer 19

1. STD

2. Vertical transmission

Question 20

Which of the following about Borrelia burgdorferi is incorrect?
A. It is transmitted by tick bite
B. Serology is by detecting IgM, undetectable in the 1st week
C. Rodent is a reserviour
D. Deer is a reserviour
E. Direct contact of rat or livestock urine through skin lesions during watersports is one of the mode of transmission

Answer 20

E

It is Leptospira interrogans!

Question 21

What is the disease caused by Borrelia burgdoferi?

Name the 3 stages involved. (never happened in hk)

Answer 21

Lyme disease
1. Localised disease: Bull-eye rash, flu-like symptoms, erythema migrans (if multuple lesions > spirochetemia)

2. Early disseminated disease: Myocarditis > Heart block Bilateral Bell palsy
3. Late stage: CNS (meningitis, neuropathy), migratory polyarthritis (years later)

Question 22

What is the treatment for Borrelia burgdorferi

Answer 22

Doxycycline, amoxicillin x2-3/52

Question 23

_______________ is caused by direct contact of rat or livestock urine through skin lesions during watersports is one of the mode of transmission. How is it diagnosed (3)

Answer 23

Leptospirosis

1. Dark-field microscopy of blood or urine
2. Culture: Fletcher’s medium
3. Serology Leptospira microscopic agglutination test (LMAT)

Question 24

Leptospirosis caused Leptospirosis presents with flu-like illness (mild, anicteric phase) +/-?
Desribe in detail (4)

Answer 24

Severe phase (10%) (icteric leptospirosis) : Weil’s disease via hematogenous spread:

1. Meningitis
2. Conjunctival suffusion
3. Liver and renal failure

Question 25

What are the treatment for Leptospira interrogans infection?

Answer 25

1. Penicillin

2. Doxycycline