B3.027 - Chronic Infections Flashcards by Annelise Chaparro

What are chronic infections

Infections that are not efficiently cleared by either the innate or adaptive immune response

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What are some examples of viruses that cause chronic infection

HIV, CMV, HSV, EBV

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What are 6 mechanisms of bacterial persistence

Antigenic variation of surface antigens
Colonization of immunoprivileged niches
Modification of intracellular environment
Host mimicry
Resistance to immune effector mechanisms
Selective gene deactivation

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What is a bacterium that displays antigenic variation of surface antigens

Borrelia burgdorferi

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What is an example of a bacterium that exhibits colonization of immunoprivileged niches

Salmonella typhi, Mycobacteria leprae

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What is type of bacteria exhibit modification of intracellular environment

facultative and obligate intracellular bacteria

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What is an example of a bacterium that exhibits host mimicry

Treponema pallidum

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What is an example of a bacterium that exhibits resistance to immune effector mechanisms

Borrelia burgdorferi

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What causes syphilis

Treponema pallidum

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What causes leptospirosis

Leptospira interrogans

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What causes relapsing fever

Several borrelia species

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What causes Lyme disease

Borrelia burgdorferi

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What makes spirochetal flagella unique

Its in the periplasmic space (in between 2 layers of plasma membrane)

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What does leptospira have on their cell surface

Lipoproteins and LPS

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What does Treponema pallidum have on its cell surface

No major ones and NO LPS (Stealth pathogen)

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What does Borellia have on its cell surface

Abundant lipoproteins NO LPS!!!

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Clinical presentation of fever, diffuse macular and papular rash of skin including palms and soles, red patches of oral mucosa is indicative of what disease

Syphilis

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What causes syphilis

Treponema pallidum

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T. Pallidum virulence factors include what

Hyalurinodase fibronectin coat
Few surface proteins
Stealth pathogen

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T. Pallidum infection (syphilis) symptoms are caused by what

Immune response to tissue damage

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How is T. Pallidum cultured

Rabbit testicles

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What is a chancre

Tissue damage at site of pathogen entry in primary syphilis

Painless, heals spontaneously

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Describe symptoms of secondary syphilis

Maculopapular, desquamative rash
slope is
Papules and Paquette in groin
Erythematous mucous patches in mouth

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What are symptoms of secondary syphilis

Maculopapular, desquamatous rash
Alopecia
Papules and plaques in groin (condylomata lata)
Erythematous mucus patches in mouth

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What are the 3 types of symtoms seen in tertiary syphilis

Gummatous Cardiovascular Neurosyphilis

Where are gummatous lesions seen

Skin, bone, brain

What does cardiovascular syphilis cause

Aortic aneurism

What can neurosyphilis cause

Meningitis Tables dorsalis - locomotor ataxia Spinal cord damage with demyelination of dorsal roots

What are symptoms of congenital syphilis

1. Stillborn 2. Saddleback nose/hutchinsonian teeth 3. 2ndary or tertiary syphilis 4. Rhinitis

What microscopy methods can you use to diagnose T. Pallidum infection

Darkfield of fresh skin lesions (NOT ORAL) | DFA staining

What serology tests can you run for T. Pallidum

1. RPR | 2. FTA-ABS

Why cant you rely on RPR alone

Its very sensitive but not specific

Why do you follow RPR with FTA-ABS

Its very specific, to confirm

What does RPR test for

Reagin antibodies against cardiolipin

What is the DOC for syphilis

Penicillin G

What do you use for syphilis in case of a penicillin allergy

Doxycycline, ceftriaxone, tetracycline, azithromycin

What is a Jarisch Herxheimer reaction presentation

Abrupt onset of fever, chills, myalgias, tachycardia, vasodilation with flushing, exacerbated skin rash, mild hypotension

What causes a Jarisch Herxheimer Reaction

Massive release of pro inflammatory cytokines triggered by release of endotoxin like substances from bacteremic organisms

What organisms can cause a Jarisch Herxheimer reaction

T. Pallidum - lipoproteins | Borrelia - Lipoproteins

What is the serotype defining molecule on Leptospira interrogans

LPS

What are asymptomatic hosts of Leptospira interrogans

Rodents Dogs Farm animals

Where does leptospira persist in its hosts

Renal tubules, shed in urine

Describe the life cycle of leptospira in a human

1. Infection via intact mucosa or broken skin 2. Septicemia 3. Damage of small blood vessel endothelium 4. Exit

What can damage of small blood vessel endothelium cause in a human

Meningitis Nephritis Hepatitis Hemorrhage

What are some occupational exposures to leptospira

Miners, vets, farmers, butchers

When do cases of leptospira peak

Warmer moths (recreational exposure)

How do you diagnose leptospira

Gold standard is agglutination test

Can you culture Leptospira

Yes but its slow Blood/urine - + during first 10 days Urine - after 1 week will be +

What microscopy method can be used to diagnose leptospira

DFA

What is the drug of choice for Leptospira

Penicillin IV

What other than penicillin can be used for Leptospira

Doxycycline preventitively Amoxicillin Ampicillin

What are two causes of relapsing fever

Tick Bourne and louse Bourne

Which type of relapsing fever causes epidemics

Louse Bourne

Which type of relapsing fever is endemic

Tick Bourne

What is TBRF caused by

Borrelia sp

What is RBRF caused by

B. Recurrent is

What causes TBRF ID

How types of ticks are fast feeders

Ornithopods, usually <20 min at night

RF borrelia are present where on the tick and how does it get to the human

Salivary glands and quickly transmitted with saliva upon feeding

How is LBRF transmitted

Crushing of louse

What causes relapses of fever from borrelia

Antigenic variation and serotype switching | Recombination fo silent genes into single expression site

Each serotype of borrelia is defined by what

Expression of a different single immunodominant surface lipoprotein

How do you diagnose borrelia causing relapsing fever

``` Blood smear (sn 70%) CDC will do a western blot but there is cross reactivity with other spirochetes so false positives can happen ```

What drug is used for TBRF

Doxycycline

What drug is used for LBRF

Tetracycline

After giving dose why do you keep patient for 12 hours

Looking out for Jarisch Herxheimer

How is Lyme disease transmitted

Lxodes ticks

What are symptoms of Lyme disease

Facial palsy | Circular rash

What is the most common vector borne disease in US

Lyme

How long do ixode ticks feed for

Several days

What is the window of time you can pull a tick off for and not get disease

48 hours

Why does it take so long for ixode ticks to transmit spirochetes

They are in the midgut and have to get to the salivary glands

What are the symptoms of Lyme disease

``` Erythema migrants (bulls eye rash) Diffuse symptoms are malaise, fatigue, headache, fever, chills, MSK pain, lymphadenopathy ```

What is diagnostic for Lyme disease as far as the EM

Over 2 inches in diameter or 5 cm

What is nueroborreliosis

Neurological symptoms of disseminate Lyme disease * meningitis * Bell’s palsy * Encephalitis * Radiculopathy * Cranial neuritis

What are the cardiac symptoms of disseminated Lyme disease

Pericarditis Myocarditis AV nodal block

What are symptoms of late disseminated Lyme disease

Encephalopathy Acrodermatitits chronicum atrophicans Oligoaricular arthritis (usually unilateral)

What virulence factor does B. Burgdorferi have to help with its colonization and survival

OspA - binds to tick midgut receptor and protects other bacterial proteins from tick Proteases

What B. Burgdorferi virulence factors help it with persistence

``` Osp C Adhesins Broad complement resistance Factor H Antigenic variation ```

What does Osp Cdo

Binds immunomodulary tick saliva protein and blocks phagocytosis by macrophages and binds complement C4b

What are CRASPs

Block MAC, complement regulator aquiring surface proteins

What causes Lyme arthritis

Lipoproteins cause constant inflammatory stimulus to join causing edema associated with neutrophil infiltration

What is the genetic link to refractory arthritis caused by antibiotics

HLA.DRB1

How does the OspA vaccine work

Recombinant lipidated Osp A blocks transmission, tick up takes antibodies killing spirochetes with OspA

B3.027 - Chronic Infections Flashcards

(84 cards)