Exam 2 Lecture 19 Flashcards by Aditi Iyer

Describe the Gram Stain of Spirochetes

Gram negative, cork-screwed bacteria

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Name 2 families in the spirochetes that are free living and non-pathogenic

Spirochaeta, Cristispira

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Name the spirochete family responsible for causing syphilis and periodontal disease

Treponema

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Where do Spirochaeta live?

Hot springs, marshes

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Where do Cristispira live?

Inside mollusks

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Name the spirochete family responsible for causing relapsing fever

Borrelia

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Name the spirochete family responsible for causing Lyme disease

Borreliella

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Name the spirochete family that is free-living but CAN be pathogenic

Leptospira

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Name the spirochete family responsible for causing dysentery (bloody diarrhea) in pigs, chicken, and sometimes humans

Brachyspira

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Which spirochete has hooked ends?

Leptospira

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What is special about the flagella of spirochetes?

It’s under the outer membrane inside the periplasmic space

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Of the spirochetes we learned about, which one has the largest genome size?

Leptospira (L. interrogans)

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Although most bacteria have a circular chromosome structure, ……. and ….. have linear chromosomes.

B. hermsii, B. burgdorferi

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How many circular chromosomes does Leptospira have?

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While B. hermsii and B. burgdorferi have a linear and circular plasmid, no plasmid has been detected in ….. and …..

Leptospirosis (L interrogans), T. pallidum

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True or False: The spirochetes we learned about all have high genetic variability

FALSE - T. pallidum has very low genetic variability

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The molecular % of G and C content is highest in which spirochete?

T. pallidum

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Which spirochete is difficult to grow in vitro culture?

T. pallidum

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Two species of spirochetes can cause relapsing fever, what are they?

B. hermsii (tick-borne) and B. recurrentis (louse-borne)

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True or False: B. hermsii is tick-borne

True

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Describe the transmission of B. hermsii in ticks

It invades the tissue of ticks and infects their ovaries, so the offspring are also infected w/ B. hermsii

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Lab studies have determined that over __ generations of ticks are born with B. hermsii due to transovarial transmission.

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True or False: In contrast to B. burgdorferi, which requires a long feeding time for infection to occur, B. hermsii requires a short feeding time

True

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What is the reservoir for ticks that can cause relapsing fever?

Squirrels, other rodents

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What is the reservoir for lice that can cause relapsing fever?

Humans (no known animal reservoir)

True or False: Louse-borne infections by. B. recurrentis can be spread from human to human.

True

True or False: B. recurrentis does not invade louse tissue

True

What is the incubation time for relapsing fever?

7 days

Name the symptoms of relapsing fever (3)

1. fever 2. headache 3. pain (muscles, joints, bones)

Spikes of fever in relapsing fever is associated with ....

High concentration of spirochetes in the blood (10^7 - 10^8 bacteria/mL)

What is the cause behind recurrent fevers?

A new serovar overgrows when the first one is overcome by the immune system

Antibodies are made against ____ ______ _____.

variable membrane proteins

New variants of B. recurrentis or B. hermsii appear in the population at a frequency of .....-...... cell per generation

10^-3 to 10^-4

True or False: New variants have a selective advantage as antibodies appear to earlier variants

True

Variation of variable membrane proteins (VMPs) is a classic example of _____ _______.

antigenic variation

VMPs are placed into 2 categories. What are they?

VSPs and VLPs | variable short proteins) and (variable long proteins

VLP and VSP genes are found on a ______ plasmid in a ____ state, where sequences can be recombined into an ______ site on another plasmid.

linear silent expression

True or False: Borrelia are normally not invasive to humans and can be cleared out within weeks

FALSE: borrelia are very invasive to humans and can infect tissues, organ systems (including CNS)

A particular ___ allele has been associated with CNS localization.

vsp

How is relapsing fever diagnosed?

Clinical features, PCR, blood films taken during fever

What is the antibiotic treatment for relapsing fever?

Penicillin & Tetracyclines

__ ________ is the main pathogen that causes Lyme Disease in the United States

B. burgdorferi

What is the main reservoir for B. burgdorferi?

Mice, birds, deer

True or False: Infection by B. burgdorferi from a tick bite is usually accidental

True

Ixodes scapularis is the main vector of Lyme Disease in North Americans, which developmental form of it the one that bites and infects animals/humans?

Nymph

True or False: The % of ticks infected with B. burgdorferi is constant throughout the US

False - NY, Minnesota, and Wisconsin have more infected ticks

Typically, a nymphal tick needs to be feeding on a mammal for at least __ hours for Lyme disease to occur

What is special about tick saliva that allows it to feed for a long period of time?

It contains factors that stop the host's blood from clotting

In order for a tick to infect its host, it needs to have _____. ____ is not enough for infection to occur.

OspC | OspA

What is the first stage of Lyme disease?

ECM (target like lesion forms)

What is the second stage of Lyme disease?

Neurologic and cardiac abnormalities; headache, stiff neck, conjunctivitis, myalgia

What is the third stage of Lyme disease?

Arthritis

How is Lyme disease diagnosed?

Evidence of ECM, biopsy, PCR

True or False: Serologic tests are unreliable and can lead to misdiagnosis of Lyme disease

True

What antibiotics are used to treat Lyme disease?

Tetracyclines, Penicillin, Ceftriaxone

True or False: B. burgdorferi has been found in tissue despite antibiotic treatment

True

Name the organism responsible for syphilis

T. pallidum

True or False: Syphilis needs high amounts of O2 for survival

False, it's a microaerophilic

T. pallidum relies heavily on host cells for its own ______. It does not synthesize nucleotides, amino acids, or fatty acids. It also does not do ___ or ____ cycle.

metabolism ETC Kreb's cycle

True or False: Similar to with relapsing fever and Lyme disease, Syphilis can disseminate and pass the blood brain barrier

True

Name the characteristics of primary Syphilis infection

genital ulcer, regional lymphadenopathy

Name the characteristics of secondary Syphilis infection

rash all over the body (including palms)

Name the characteristics of tertiary Syphilis infection

gumma, CV syphilis, paralysis, blindness

True or False: Syphilis can cross the placenta to cause congenital syphilis

True

Name the possible consequences of congenital syphilis

premature baby, spontaneous abortion, stillbirth, illness, latent infection

When syphilis is untreated, the primary and secondary lesions are eventually ____, however infection remains ______

cleared | systemically

Some outer membranes for Syphilis bind ......, ......., .......

fibronectin laminin fibrinogen

What is TprK?

A surface-exposed protein expressed by T. pallidum

TprK has __ variable regions, but over ___ donor sites

7, 50

How is syphilis diagnosed?

Serologic testing, darkfield microscopy * *PCR is not available commercial * *No culture available

What is the first line antibiotic treatment for syphilis?

Penicillin

Name 2 alternative antibiotics used for treating syphilis

Doxycycline, tetracyclines

Syphilis strains have higher levels of resistance against ______

Macrolides

L. interrogans, which causes Leptospirosis, has ____ serovars

300

In contrast to other spirochetes discussed, L. interrogans is ________

free-living

Where is L. interrogans found?

in water

What is the reservoir of L. interrogans?

Wild/domestic animals (raccoons, opossums, skunks)

What is the source of L. interrogans in water?

It is contaminated by infected urine of animals like mice

What age groups are most at risk for Leptospirosis?

Teens, young adults

The bacterial load can reach up to ____/gram of tissue in the kidneys

10^10

Although most individuals who get Leptospirosis are asymptomatic or have non severe symptoms, some people can get diseases such as:

renal failure jaundice aseptic meningitis pulmonary hemorrhage

What is the incubation period of Leptospirosis?

7-10 days

Leptospirosis is particularly dangerous when in the _____ form

icteric

How is Leptospirosis diagnosed?

1. PCR 2. Culture 3. Serology (ONLY IN LATER INFECTION)

Blood, and CSF samples are used in ___ stages of leptospirosis, while _____ samples are used in _____ leptospirosis

early urine late

Name the antibiotic treatment used for Leptospirosis

Penicillin, doxycycline, erythromycin