Spirochetes & Vibrios

Question 1

List 8 recurring themes for spirochetes

Answer 1

1. wide variety of transmission
2. cross very easily to bloodstream
3. primary virulence factors = immune evasion
4. very low inflammation
5. no vaccines b/c not very immunogenic
6. diagnosis is challenging
7. little acquired abx resistance b/c doesn’t pass around plasmids
8. Jarisch-herxheimer rxn to treatment

Question 2

What is the Jarisch-herxheimer rxn to treatment?

Answer 2

It is one of the recurring themes found in spirochete infections and is when patient develops flu-like symptoms 24 hrs post-abx treatment.

Question 3

Spirochetes belong into 3 genus

Answer 3

1) treponema (syphillus, yaws, pintas)
2) leptospira (leptospirosis)
3) borrelia (lyme disease, relapsing fever)

Question 4

Describe the movement of the small treponema pallidum

Answer 4

flagellar “corkscrew” motion

Question 5

Can treponema pallidum survive outside of humans?

Answer 5

Treponema pallidum is human restricted and cannot survive outside of host.

Question 6

Can treponema pallidum be grown in culture?

Answer 6

No

Question 7

Treponema pallidum will cause syphilis. What’s the difference btw acquired and congenital syphilis?

Answer 7

Congenital syphilis is transferred from mom to fetus thru blood. Acquired syphilis is gotten from sex.

Question 8

In acquired syphilis, there’s full body infection in day 1 due to what characteristic of spirochetes?

Answer 8

it can readily cross membranes and into bloodstream, but it’s not immunogenic enough to cause shock

Question 9

In acquired syphilis, CNS is invaded relatively early. Do symptoms develop immediately? What are the signs of CNS involvement?

Answer 9

Symptoms make take years to develop. First, CSF is abnormal (subarachnoid space), then meninges then brain parenchyme.

Question 10

In acquired syphilis, host raises humoral immunity against treponema syphillis, but don’t clear infection. Why?

Answer 10

B/c surface of spirochetes is non-immunogenic. Also spirochetes downregulate TH1 cells, which help activate macrophages.

Question 11

Primary syphilis is highly infectious. What are the symptoms and what is the treatment?

Answer 11

Patient will present with painless chancre at site within 3-6 weeks of infection. The chancre will heal, but syphilis will remain. Treatment is one shot of penicillin.

Question 12

Why is secondary syphilis, which occurs when primary syphilis isn’t cured harder to diagnose?

Answer 12

it is much harder to diagnose because of variable symptoms. Patient can present with fever, malaise, myalgias. Nothing that will directly tie it to syphilis, especially if patient doesn’t mention chancre that has gone away.

Question 13

What is reagin?

Answer 13

useless antibodies found in someone with secondary syphilis

Question 14

2/3 of secondary syphilis will become

Answer 14

latent syphilis serving as reservoir of treponema pallidum

Question 15

The other 1/3 of secondary syphilis will become tertiary syphilis, which can cause a wide range of symptoms

Answer 15

1. cardiovascular syphilis (aneurysm of ascending aorta)
2. gummatous syphilis in liver, bone, testes seen as granulomas with rubbery, necrotic centers
3. neurosyphilis

Question 16

What are the 3 kinds of neurosyphilis?

Answer 16

1. syphilitc meningitis (usu. occurs early on around 6 months post-exposure)
2. meningovascular syphilis will damage blood vessels of meninges, brain and spinal cord
3. parenchymal neurosyphilis leading to impaired sensation, wide-based gait and loss of pain and sensation due to disruption of dorsal roots.

neurosyphilis can cause general paresis and dementia

Question 17

What does the Argyll-Robertson Pupil Exam test for?

Answer 17

It can detect neurosyphilis.

• 1 or both pupils will fail to constrict in response to light (neg pupillary reflex uni or bilaterally)
• but both pupils will constrict when testing for accommodation (positive accommodation test).

Question 18

Infants with congenital syphilis will develop what kinds of symptoms within first two years of life?

Answer 18

severe secondary syphilis (fever, malaise, myalgias, etc)

Question 19

Often times, fetuses infected with treponema pallidum will

Answer 19

be stillborn, miscarried in 40-50% of cases

Question 20

Borrelia burgdorferi is a spirochete that can cause which disease

Answer 20

Lyme Disease

Question 21

Treponema pallidum is motile and so is borrelia burgdorferi. Describe their movements

Answer 21

Treponema pallidum has a flagellar corkscrew motion. Borrelia burgdorferi has a flatwave, not spiral movement

Question 22

Unlike treponema pallidum which is too small to be seen under std light microscopy, borrelia burgdorferi can be seen. But it needs special stain, such as

Answer 22

silver stain

Question 23

What are the 2 general reservoirs of borrelia burgdorferi?

Answer 23

1. small mammals carrying nymph (immature, young ticks)

2. large mammals carrying adult ticks

Question 24

How long does it take ticks to transmit lyme disease?

Answer 24

about 24-48 hours, which is why checking oneself for ticks everyday in endemic areas can be a great preventative measure

Question 25

How to remove a tick?

Answer 25

1) use gloves bc tick's saliva is infectious | 2) remove with tweezer

Question 26

What is the abx of choice to treat lyme disease? Are there any contraindications of this abx?

Answer 26

Use doxycycline for 10-20 days, but cannot be given to pregnant women or people allergic to tetracycline

Question 27

Lyme disease has 3 phases after tick injects borrelia burgorferi into host. Explain the 1st phase.

Answer 27

1st phase; organisms will spread in the next 6 months; 70% of people will have bullseye rash at site; erythema migrans rash (which will increase in size); autoantibodies

Question 28

The 2nd stage of lyme disease

Answer 28

- no more rash - immune and/or neurological disorders * *harder to diagnose b/c no erythema migrans

Question 29

The 3rd stage of lyme disease aka Post-Lyme

Answer 29

-more severe immune and neurological disorders

Question 30

Can someone get lyme disease more than once?

Answer 30

Yes, reinfection can occur.

Question 31

What is important in diagnosing lyme disease?

Answer 31

Taking a careful history (season, geographic location, timeframe) -patient can have co-infection and present with fever

Question 32

What are some lab tools that can diagnose lyme disease and who might have false positives?

Answer 32

serology, ELISA, and IFA can confirm Lyme Disease but not until 6 months laters. A problem is there are some people vaccinated against Lyme so will have false positives.

Question 33

Treponema requires special technique to be visualized

Answer 33

dark field

Question 34

With these spirochete infections, treatments are easy once diagnosis is made. The problem is with diagnosing. Explain

Answer 34

In syphilis, after it passes the primary syphilis phase, there will not be clearly identifiable chancres. Likewise, in lyme disease, after the first phase, there will be no presentation of erythema migrans. Hence, with these, it's best to diagnose early and treat early.

Question 35

At times, people in endemic areas of lyme disease will get treated with prophylactic abx, what reaction can actually confirm diagnosis of lyme disease?

Answer 35

Jarisch-herxheimer rxn which is when patient presents with flu-like symptoms after abx treatment of spirochete infections (lyme, syphillis)

Question 36

Vibrios are not cocci, bacilli or spirochetes. Describe their shape.

Answer 36

Vibrios are gram negative rods, and are mostly ocean dwelling halophiles (love salt).

Question 37

Are spirochetes gram negative or gram positive?

Answer 37

Spirochetes are not classified as either gram negative or gram positive

Question 38

In addition to causing gastroenteritis, vibrios are now known to be linked to

Answer 38

peptic ulcer disease

Question 39

Describe the shape of Vibrio Cholera

Answer 39

Vibrio Cholera is a curved, comma-shaped motile Gram negative rod.

Question 40

Is Vibrio Cholera an obligate anaerobe, obligate aerobe or facultative anaerobe?

Answer 40

Facultative anaerobe

Question 41

What are the two reservoirs of Vibrio Cholera?

Answer 41

1. in humans | 2. planktonecosystem of Indian Ocean

Question 42

Vibrio Cholera is usually not pathogenic. How does it become pathogenic?

Answer 42

Vibrio Cholera undergo genetic changes via lysogenic bacteriophage colonization to become pathogenic

Question 43

What are two ways V cholera is transmitted?

Answer 43

1. fecal-oral route | 2. shed by asymptomatic carriers

Question 44

Vibrio Cholera has a high infectious dose that is normally killed by stomach acid. Explain the pathogenesis of V. Cholera

Answer 44

1. bacteria that survive the stomach will go to the small intestines 2. secrete mucinase, which will clear path to brush border, attach, colonize inside lumen of intestine 3. growing bacteria secrete cholera toxin (aka chloragen) 4. chloragen (ab subunit) -will persistently activate adenylate cyclase leading to loss of water and ions 5. blocks absorption by microvilli while also promoting secretion from crypts

Question 45

What toxin does Vibrio Cholera secrete?

Answer 45

Chloragen (ab subunit) -b unit for docking and a unit with enzymatic activity to stimulate adenylate cyclase leading to loss of water and ions

Question 46

Where does Vibrio Cholera get its virulence factors?

Answer 46

from a lysogenic bacteriophage CTX

Question 47

What is the major symptom of Cholera?

Answer 47

MASSIVE watery diarrhea

Question 48

Will Abx help with treating Cholera?

Answer 48

No, the infection is self-limiting; will clear within a week. The problem is due to dehydration and electrolyte imbalance.

Question 49

If your patient presents with cholera, what should you focus on in terms of treatment?

Answer 49

Make sure that the patient is well hydrated and his/her electrolytes are balanced

Question 50

How to evaluate how dehydrated someone with cholera is?

Answer 50

There's a pinch test in which you pinch the patient and watch to see how long it takes the site to get back to normal coloration. The more dehydrated the patient, the longer it takes for the skin to get back to normal.

Question 51

Another Vibrio is Helicobacter pylori. Describe its shape.

Answer 51

Helicobacter pylori is a curved gram negative rod.

Question 52

What is helicobacter pylori (Vibrio) hallmark virulence factor?

Answer 52

Urease + which will break down urea into ammonia

Question 53

How is helicobacter pylori transmitted?

Answer 53

Unknown; probably human to human

Question 54

Explain the pathogenesis of H. Pylori

Answer 54

1. bacteria with flagella swim and attach to mucus-secreting cells of stomach 2. produce urease to break down urea (normal in stomach) to ammonia (abnormal) 3. increased levels of ammonia will increase pH allowing bacteria to grow and form ulcers and irrate gut wall

Question 55

What are the two ways to diagnose someone with peptic ulcer disease caused by h. pylori?

Answer 55

Radiolabeled Urea-breath test 1. Pt drinks radiolabeled urea 2. if infected, will exhale radiolabeled CO2 Check stool sample for antigens to h. pylori but very expensive

Question 56

How to treat people with h. pylori?

Answer 56

1. peptobismol 2. proton pump inhibitor 3. 10-14 days of trio of abx

Question 57

What's the most pathogenic strain of v. cholera?

Answer 57

most pathogenic strain has O1 genetic marker of colonization by lysogenic bacteriophage

Question 58

When was H. Pylori discovered?

Answer 58

1983

Question 59

What clinical conditions are linked to infection with h. pylori?

Answer 59

peptic ulcer disease and gastric cancers

Question 60

Who is more susceptible to getting cholera?

Answer 60

People who are on antacids and have had gastrectomies.