BUGS/VIRUSES BLOCK 4

Question 1

T.palludium wraps itself in fibronectin which damages cells, causing the release of lipids. The RPR test is positive if ?

Answer 1

the pt makes IgM or IgG against those lipids (reacts to cardiolipin)

People with lupus may test + for this, even though they don’t have syphilis (type III HSR) ; so is being pregnant or in elderly pts.

Question 2

Steiner silver stain to visualize what ?

Answer 2

Spirochetes

Question 3

Are spirochetes part of normal flora ?

Answer 3

Yes, they can be in oral, genital and anal mucosa.

Question 4

How good is VDRL for dx of syphilis ?

Answer 4

Primary stage syphilis : high rate of false negatives;
Secondary stage syphillis : 95% sensitive ;
Tertiary syphllis a little bit less sensitive for people who are untreated at this point.

Question 5

What test is most sensitive to detect syphilis in all 3 stages ?

Answer 5

FTA-Abs/TPHA

Question 6

What test is used to see if the pt is actually making antibodies against the syphilis bacteria ?

Answer 6

FTA-Abs/TPHA

Question 7

Screening test for syphilis ?

Answer 7

VDRL

Question 8

What media for growth of F.tularensis ?

Answer 8

Very fastidious - very difficult to grow in culture - specialized agar supplemented with chocolate or chacoal agar.
Plates must be incubated for > 3 days.

Question 9

Painful papule at infected tick bite site, necrotic lesion with raised borders followed by regional lymphadenopatht ?

Answer 9

Ulceroglandular tularemia (F.tularensis)

Question 10

What TLR gets activated in case of intracellular infection with F. tularensis ?

Answer 10

NOD-like receptors

Question 11

Irregularly shaped gram-negative bacteria that can replicate inside macrophages ?

Answer 11

F. tularensis

Question 12

Causes cat scratch fever ?

Answer 12

Bartonella henselae

Warty lesions, usually self-resolving

Question 13

Causes cellulitis with no particular pattern of spreading, following cat or dog bite ?

Answer 13

Pasteurella multocida

Question 14

Obligately-anaerobic small rods that stain gram-negative, but have cell membranes that look more like gram+ (they don’t have LPS). Can act as normal flora in the vagina or cause bacterial vaginosis ?

Answer 14

Mobiluncus
Gardnerelia vaginalis

Question 15

Part of normal flora, but main causative agent of anaerobic peritoneal infections or post surgical infecitons ? Can also cause brian abcesses in CMI deficient patients.

Answer 15

B. fragilis

Very antibiotic resistant

Question 16

Trx of B. fragilis ?

Answer 16

Metronidazole

Question 17

Their LPS is altered so it does not bind TLR-4 ?

Answer 17

B. fragilis

Question 18

Can transition from rough strains that lack O-polysaccharides of LPS to smooth strains that have a lot of polysaccharides and can escape macrophages leading to spreading granulomas and ondulent systemic symptoms ?

Answer 18

Brucella

Question 19

Lives in amobae and can live inside our macrophages

Answer 19

Legionella

Question 20

Causes pontiac fever

Answer 20

Legionella

Can progress to legionnaires’ disease in people who are at risk : heavy smokers, drinkers, elderly.
Defective cilia, unproductive cough.

Question 21

How do you test for legionella ?

Answer 21

legionella specific antigens are passed in the urine of infected pts for 1 month-1year.

Question 22

Treatment for legionella

Answer 22

Macrolide or quinolone,
NOT a beta-lactam

Question 23

Grow on buffered-charcoal yeast extract with antifungal additives into white ground class colonies ?

Answer 23

Legionella

Question 24

Very small, non-motile, gram-negative rod very hard to see on gram stain, obligate intracellular pathogen :

Giemsa or silver staining techniques are used instead.

Answer 24

Rickettsiae

Intracellular growth prevents immune clearance
Grows in endothelial cells and epithelial cells (non-profesionnal phagocytes)

Question 25

Causes Rocky Mountain Spotted Fever?

Answer 25

Rickettsia rickettsii | Vector : tick born Reservoirs : ticks and wild rodents ## Footnote High fever, classic petechial rash (vasculitis) that starts at in palms/soles and then migrates to the trunk, myalgias, headache with possible photophobia.

Question 26

What type of tick spreads Rocky Mountain Spotter Fever ?

Answer 26

American dog tick.

Question 27

How do you treat Rocky Mountain Spotted Fever ?

Answer 27

Macrolides | or other tranlation-stopping atb

Question 28

Rickettsia prowazekii is responsible for what disease that is spread by human body lice and typically affect homeless individuals ?

Answer 28

Epidemic typhus/Brill-Zinsser disease ## Footnote High fever, severe headache, myalgia, rose spots rash because of vasculitis from growth in endothelial cells. The high fever can last 2 weeks, and the myalgia can persisit for 2-3 months.

Question 29

What can you catch from rolling around in the mud ?

Answer 29

Leptospira interogans ## Footnote Contact with bodily fluid required, like other spirochetes diseases (syphilis, Lyme’s) but this bacteria can live for a long time in water ; you get exposed to the water which is contaminated by urine of infected animal – wild mammals such as rodents, fox.

Question 30

What is Weil's disease ?

Answer 30

Serious complication of Leptospora infections that involves the kidney, liver and mininges.

Question 31

Treatment for Leptospora?

Answer 31

Penicillin | Untreated, 30% CFR

Question 32

R. typhi/R.felis causes :

Answer 32

Endemic/murine typhus | Native to rodents and cats ; spread by cat fleas ## Footnote Sx similar to R. prowazekii but less severe, with sx lasting < 1 month and not recurring. Dx based on serology or PCR, NOT culture. Usually treated with Doxycycline / tetracycline

Question 33

How do Ehrlichia and Anaplasma replicate in WBCs ?

Answer 33

They stop phagosome-lysosome fusion

Question 34

What species of ticks spread Ehrlichia and Anaplasma ?

Answer 34

Ixode and Lone Star ticks that fed on infected mice or deer.

Question 35

Infect monocytes, can cause flu-like sx, causes body rash in < 40% ?

Answer 35

Ehrlichia

Question 36

Infect granulocytes, causes flu-like sx, <10% of patients will have a rash ?

Answer 36

Anaplasma

Question 37

Obligate intracellular bacteria that lack peptidoglycans and have no cell walls ?

Answer 37

Mycoplasma Ureaplasma Chlamydia Chlamydophila

Question 38

Obligate intracellular bacteria that lack peptidoglycans and have no cell walls, can make their own ATP ?

Answer 38

Mycoplasma Ureaplasma

Question 39

Obligate intracellular bacteria that lack peptidoglycans and have no cell walls, can't make their own ATP, and must use ATP made by their host cells ?

Answer 39

Chlamydia Chlamydophila

Question 40

Nb 1 cause of walking pneumonia ?

Answer 40

Mycoplasma pneumoniae | Binds to ciliated respiratory epithelia via P1 adhesin on pilus surface

Question 41

Prime age for walking pneumonia ?

Answer 41

5-15 years old

Question 42

IgM in serum clumps RBCs at 4C (cold agglutinin) ?

Answer 42

Mycoplasma pneumoniae

Question 43

Part of normal flora, but can cause urethritis in a small portion of individual who carry them ?

Answer 43

Ureaplasma urealyticum Mycoplasma hominis Mycoplasma genitalium

Question 44

STI which the only PAMP is DNA inside vacuoles that binds TLR-9, lacks the capacity to make ATP on its own ?

Answer 44

Chlamydiae

Question 45

Switches between Elementary body forms which are non, metabolically active, but more transmissible to reticulate bodies, which are metabolically active and nontransmissible ; switch b/w 2 forms responsible for undulant fever of disease :

Answer 45

Chlamydiae

Question 46

Nb 1 cause of pelvic inflammatory disease and can cause ectopic pregnancy if untreated ?

Answer 46

Chlamydiae

Question 47

Conjunctivitis with inversion of eyelashes typical of ?

Answer 47

Trachoma conjunctivitis (Chlamydiae in the eye) | Can cause scarring and blindness

Question 48

Cause conjunctivitis which can be spread by face flies ?

Answer 48

Chlamydiae