Unusual bugs Flashcards
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
All of the above
State the transmission method of Coxiella burnetti. (2)
- Coxiella: spores survive in animal feces
2. Direct contact with farm animals/aerosol
Rickettsia invades endothelial cells lining capillaries and cause _______________.
Diffuse vasculitis
How are Rickettsia infections diagnosed? (3)
- Complement fixation test
- Antibody detection: immunofluorescence stain
- Weil-Felix test: cross reaction (agglutination test) of Rickettsia Ag with OX strains of Proteus vulgaris (no longer used)
What are the general clinical presentations of Rickettsia infected patients? (3)
General Triad of fever, rash, headache
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
RMSF
- Centripetal rash (benign peripherally on ankles and wrist > trunk)
- Chills
- Fever
Name the types of bacteria under the Typhus group of Ricketssia. (3) State their respecitive vector.
- Rickettsia prowazekii : louse-borne
- Rickettsia typhi: flea-borne
- Rickettsia tsutsugamushi: mite-borne
List all the clinical prensention caused by Rickettsia prowazekii. (6)
- Epidemic typhus (widespread)
- Rash sparing the face, head and feet
- Pneumonia
- Encephalitis
- Myalgia
- Arthralgia (joint pain)
What is Brill Zinsser disease?
- Weil-Felix test +/-?
- With/ without rash?
The recurrent form of typhus after years
- Weil-Felix test -ve
- without rash
_____________ causes endemic typus. It contains OX19.
Rickettsia typhi
- edemic = localized
Rickettsia tsutsugamushi (OXK) causes _________, clinical presentaions include fever, intense headache, wound that eventually develop into __________.
Scrub typhus;
eschar
Other than the Spotted fever group and Typus group, name the other group of Rickettsia and the bacteria that belongs it this group.
Q fever group
- Coxiella burnetti
How is Coxiella burnetti transmitted?
How is it diagnosied?
Inhaltion, extremely low infectious dose, 1-10 bacteria
Diagnosed by serology: complement fixation test
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
All except A
Endocarditis is rare and chronic, in immunocompromised patients
What is the treatment of Ricketssia infections?
How about for Q fever endocarditis?
- Doxycycline x2/52
- Q fever endocarditis: Doxycycline + hydroxychloroquine x 18m
List the hallmarks of Chronic Q infection. (5) (hallmark usually hits one only?)
- Culture negative endocarditis (60-70% of chronic Q)
- Intravascular infections (mycotic aneurysm, vascular graft infection)
- Chronic granulomatous hepatitis (Doughnut granulomata or fibrinous ring granuloma)
- Osteoarticular infections
- Abortion, stillbirth
Name the 3 types of Spirochetes that you have learnt.
- Treponema pallidum
- Borrelia burgdorferi
- Leptospira interrogans
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?
Spiral G- rods;
Leptospira with a question mark shape
What are the 2 modes of transmission of Treponema pallidum?
- STD
2. Vertical transmission
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
E
It is Leptospira interrogans!
What is the disease caused by Borrelia burgdoferi?
Name the 3 stages involved. (never happened in hk)
Lyme disease
1. Localised disease: Bull-eye rash, flu-like symptoms, erythema migrans (if multuple lesions > spirochetemia)
- Early disseminated disease: Myocarditis > Heart block Bilateral Bell palsy
- Late stage: CNS (meningitis, neuropathy), migratory polyarthritis (years later)
What is the treatment for Borrelia burgdorferi
Doxycycline, amoxicillin x2-3/52
_______________ 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)
Leptospirosis
- Dark-field microscopy of blood or urine
- Culture: Fletcher’s medium
- Serology Leptospira microscopic agglutination test (LMAT)
Leptospirosis caused Leptospirosis presents with flu-like illness (mild, anicteric phase) +/-?
Desribe in detail (4)
Severe phase (10%) (icteric leptospirosis) : Weil’s disease via hematogenous spread:
- Meningitis
- Conjunctival suffusion
- Liver and renal failure
What are the treatment for Leptospira interrogans infection?
- Penicillin
2. Doxycycline
