BUGS/VIRUSES BLOCK 4 Flashcards
T.palludium wraps itself in fibronectin which damages cells, causing the release of lipids. The RPR test is positive if ?
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.
Steiner silver stain to visualize what ?
Spirochetes
Are spirochetes part of normal flora ?
Yes, they can be in oral, genital and anal mucosa.
How good is VDRL for dx of syphilis ?
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.
What test is most sensitive to detect syphilis in all 3 stages ?
FTA-Abs/TPHA
What test is used to see if the pt is actually making antibodies against the syphilis bacteria ?
FTA-Abs/TPHA
Screening test for syphilis ?
VDRL
What media for growth of F.tularensis ?
Very fastidious - very difficult to grow in culture - specialized agar supplemented with chocolate or chacoal agar.
Plates must be incubated for > 3 days.
Painful papule at infected tick bite site, necrotic lesion with raised borders followed by regional lymphadenopatht ?
Ulceroglandular tularemia (F.tularensis)
What TLR gets activated in case of intracellular infection with F. tularensis ?
NOD-like receptors
Irregularly shaped gram-negative bacteria that can replicate inside macrophages ?
F. tularensis
Causes cat scratch fever ?
Bartonella henselae
Warty lesions, usually self-resolving
Causes cellulitis with no particular pattern of spreading, following cat or dog bite ?
Pasteurella multocida
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 ?
Mobiluncus
Gardnerelia vaginalis
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.
B. fragilis
Very antibiotic resistant
Trx of B. fragilis ?
Metronidazole
Their LPS is altered so it does not bind TLR-4 ?
B. fragilis
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 ?
Brucella
Lives in amobae and can live inside our macrophages
Legionella
Causes pontiac fever
Legionella
Can progress to legionnaires’ disease in people who are at risk : heavy smokers, drinkers, elderly.
Defective cilia, unproductive cough.
How do you test for legionella ?
legionella specific antigens are passed in the urine of infected pts for 1 month-1year.
Treatment for legionella
Macrolide or quinolone,
NOT a beta-lactam
Grow on buffered-charcoal yeast extract with antifungal additives into white ground class colonies ?
Legionella
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.
Rickettsiae
Intracellular growth prevents immune clearance
Grows in endothelial cells and epithelial cells (non-profesionnal phagocytes)
Causes Rocky Mountain Spotted Fever?
Rickettsia rickettsii
Vector : tick born
Reservoirs : ticks and wild rodents
High fever, classic petechial rash (vasculitis) that starts at in palms/soles and then migrates to the trunk, myalgias, headache with possible photophobia.
What type of tick spreads Rocky Mountain Spotter Fever ?
American dog tick.
How do you treat Rocky Mountain Spotted Fever ?
Macrolides
or other tranlation-stopping atb
Rickettsia prowazekii is responsible for what disease that is spread by human body lice and typically affect homeless individuals ?
Epidemic typhus/Brill-Zinsser disease
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.
What can you catch from rolling around in the mud ?
Leptospira interogans
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.
What is Weil’s disease ?
Serious complication of Leptospora infections that involves the kidney, liver and mininges.
Treatment for Leptospora?
Penicillin
Untreated, 30% CFR
R. typhi/R.felis causes :
Endemic/murine typhus
Native to rodents and cats ; spread by cat fleas
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
How do Ehrlichia and Anaplasma replicate in WBCs ?
They stop phagosome-lysosome fusion
What species of ticks spread Ehrlichia and Anaplasma ?
Ixode and Lone Star ticks that fed on infected mice or deer.
Infect monocytes, can cause flu-like sx, causes body rash in < 40% ?
Ehrlichia
Infect granulocytes, causes flu-like sx, <10% of patients will have a rash ?
Anaplasma
Obligate intracellular bacteria that lack peptidoglycans and have no cell walls ?
Mycoplasma
Ureaplasma
Chlamydia
Chlamydophila
Obligate intracellular bacteria that lack peptidoglycans and have no cell walls, can make their own ATP ?
Mycoplasma
Ureaplasma
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 ?
Chlamydia
Chlamydophila
Nb 1 cause of walking pneumonia ?
Mycoplasma pneumoniae
Binds to ciliated respiratory epithelia via P1 adhesin on pilus surface
Prime age for walking pneumonia ?
5-15 years old
IgM in serum clumps RBCs at 4C (cold agglutinin) ?
Mycoplasma pneumoniae
Part of normal flora, but can cause urethritis in a small portion of individual who carry them ?
Ureaplasma urealyticum
Mycoplasma hominis
Mycoplasma genitalium
STI which the only PAMP is DNA inside vacuoles that binds TLR-9, lacks the capacity to make ATP on its own ?
Chlamydiae
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 :
Chlamydiae
Nb 1 cause of pelvic inflammatory disease and can cause ectopic pregnancy if untreated ?
Chlamydiae
Conjunctivitis with inversion of eyelashes typical of ?
Trachoma conjunctivitis (Chlamydiae in the eye)
Can cause scarring and blindness
Cause conjunctivitis which can be spread by face flies ?
Chlamydiae
