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spiral bacteria: spirochaetes Flashcards

1
Q

name the bacteria species part of spirochaetes

A

treponema pallidum
spirillum minus; streptobacillus moniliformis
leptospira interrogans
borrelia spp.: relapsing fever group (b. recurrentis, b. duttoni), lyme disease group (b. burgdorferi)

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2
Q

name the bacteria species that are “spiral” and not spirochaetes

A

campylobacter and helicobacter spp.

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3
Q

treponema pallidum: histology

A

dark ground illumination; too fine to be stained by any routine staining method

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4
Q

treponema pallidum: culture

A

cannot be cultured using any solid or liquid medium

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5
Q

treponema pallidum: transmission

A

via blood; sexually transmitted disease, vertical transmission, blood transfusion, transplants

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6
Q

treponema pallidum: clinical presentations

A

syphilis

primary syphilis:

  • chancre (typically painless ulcers) develops, often on genitalia
  • enlargement of local lymph nodes
  • extragenital sites may be affected too; mouth, lips, anal canal, finge
  • increases chances of concomitant hiv infection

secondary syphilis: treponemes spread throughout body

  • rash (can be macular, papular or pustular), often involving palms and soles
  • mucous patches (lesions on mucous membranes)
  • condylomata lata (warty lesions around anus, genitals or other warm most areas)
  • generalised enlargement of lymph nodes
  • acute meningitis may occur

latent syphilis:

  • all signs disappear, but secondary lesions may relapse
  • 70% does not develop further disease, the rest develop chronic symptomatic infection

meningeal syphilis:

  • may occur within afew months to a year of infection
  • chronic meningitis presents with headache, nausea, neck stiffness and other neurological signs

late complications: tertiary + quarternary syphilis

  • neurosyphilis; meningovascular syphilis (stroke after a period of other cns disease), general paresis of the insane (chronic progressive state which terminates in dementia due to the disease of the cerebral cortex), tabes dorsalis: demyelination of the posterior columns of spinal cord and dorsal roots/ganglia, leading to loss of proprioception and sensations
  • gummatous syphilis; granulomatous lesions which become necrotic, leading to guma formation on skin, mucous membranes or bone
  • cardiovascular syphilis; aortitis of the thoracic aorta, can lead to narrowing of the origin of the coronary arteries, aortic incompetence and aortic aneurysm

congenital syphilis: t. pallidum can cross the placenta; part of antenatal screening
- may induce abortion
neonatal bullous rash, goes on to develop early lesions resembling secondary syphilis and late lesions (gummatous, neurosyphilis)
- hutchinson’s triad: 8th nerve deafness, nterstitial keratitis (clouding of cornea leading to blindness), hutchinson’s teeth

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7
Q

treponema pallidum: diagnosis (serology)

A

non-treponemal antibody tests: rapid plasma reagin and venereal disease reference laboratory

  • advantages: titre fluctuates with the intensity of disease, progressively falls with successful treatment
  • disadvantages: false positive reactions, decreasing titrs occurs even without treatment after time

treponemal antibody tests: t. pallidum haemagglutination test, t. pallidum particle agglutination test and fluorescent treponemal antibody test

  • advantges: lower false positive rates
  • disadvantages: stays raised for a very long time, even after successful treatment

combined approach: do vdrl + tpha, if either are positive then carry out fta-abs

  • note: all may be negative during early primary syphilis
  • *note: other diseases endemic in other parts of the world caused by closely related treponema spp. are not sexualy transmitted also give positive serological tests
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8
Q

treponema pallidum: treatment

A

iv benzylpenicillin

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9
Q

spirillum minus + streptobacillus moniliformis: histology:

A

gram negative spiral (s. minus)

gram negative non-spiral (s. moniliformis)

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10
Q

spirillum minus + streptobacillus moniliformis: character

A

most cases in japan and africa (s. minus)

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11
Q

spirillum minus + streptobacillus moniliformis: transmission

A

contaminated milk, water (s. moniliformis)

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12
Q

spirillum minus + streptobacillus moniliformis: clinical presentations

A

s. minus: rat bite fever
s. moniliformis: haverhill fever

local lesion (skin ulcer or abcess), local lymphadenopathy, fever, possible skin rash

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13
Q

leptospira interrogans: character

A

chronically excreted in urine of rats and other animals, commonest in the tropics

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14
Q

leptospira interrogans: transmission

A

entry through skin, upper respiratory tract, eyes

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15
Q

leptospira interrogans: clinical presentations

A

leptospirosis

bactaeremic leptospirosis: flu-like, high fever, muscle pain, possibly conjunctival congestion, followed by immune phase with signs of meningeal irritation (aseptic meningitis; headache, vomitting)

weil’s disease (icteric leptospirosis): jaundice, haemorrhages (including pulmonary), renal failure, conjunctival congestion, potentially fatal

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16
Q

leptospirosis interrogans: diagnosis

A

serology, culture (difficult), dark-ground microscopy of urine and blood (difficult)

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17
Q

leptospirosis interrogans: treatment

A

iv benzylpenicillin

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18
Q

name the 2 borrelia spp. groups:

A

relapsing fever group: b. recurrentis, b. duttoni

lyme disease group: b. burgdorferi

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19
Q

relapsing fever group: histology

A

extracellular spiral bacteria seen in peripheral blood film

transmission: louse (b. recurrentis), soft ticks (b. duttoni)

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20
Q

relapsing fever group: transmission

A

louse (b. recurrentis), soft ticks (b. duttoni)

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21
Q

relapsing fever group: virulence factors

A

antigenic variation

22
Q

relapsing fever group: clinical presentations

A

relapsing fever

periods of fever alternating with afebrile intervals due to antigenic variation

b. recurrentis: epidemic louse-borne relapsing fever, 40% mortality rate
b. duttoni: endemic tick-borne relapsing fever

23
Q

relapsing fever group: diagnosis

A

peripheral blood films

24
Q

relapsing fever group: treatment

A

doxycycline (watch out for jarisch-herxheimer reaction)

25
Q

lyme disease group: character

A

extensive animal reservoirs (deers, rodents)

26
Q

lyme disease group: transmission

A

hard tick bites

27
Q

lyme disease group: clinical presentations

A

lyme disease

stage 1: erythema chronicum migrans; rash begins at site of bite, then spreads out in a ring, may be associated with systemic disease, including cns

stage 2: (weeks/months later) neurologial, cardiac or musculoskeletal disease (arthritis)

stage 3: (months/years later) chronic skin, joint or neurological disease

**note: congenital infection may occur

28
Q

lyme disease group: diagnosis

A

serology

29
Q

lyme disease group: treatment

A

depends on disease stage, but for erythema chronicum migrans, doxycycline

30
Q

campylobacter & helicobacter spp.: biochemical tests

A

oxidase positive

31
Q

campylobacter & helicobacter spp.: histology

A

gram negative short spirals

32
Q

campylobacter & helicobacter spp.: culture

A

grow on selective media with antibiotic cocktail

33
Q

campylobacter & helicobacter spp.: character

A

microaerophilic; cannot grow at atospheric oxygen concentration nor in its absence entirely

34
Q

name the 3 campylobacter spp.:

A

campylobacter fetus, campylobacter coli, campylobacter jejuni

35
Q

campylobacter fetus: character

A

causes abortion in sheep and cows

36
Q

campylobacter fetus: clinical presentations

A

occasional cause of diarrhoae
septicaemia in immunocompromise
rare cause of septic abortion in men

37
Q

campylobacter jejuni, campylobacter coli: culture

A

selective medium with antibiotics to suppress colonic flora, incubated under microaerophilic conditions at 42 deg

38
Q

campylobacter jejuni, campylobacter coli: character

A

found in range of animals, especially birds/chickens

39
Q

campylobacter jejuni, campylobacter coli: transmission

A

faecal oral, contaminated blood

40
Q

campylobacter jejuni, campylobacter coli: epidemiology

A

important cause of acute gastroenteritis - traveller’s diarrhoea in southeast asia

41
Q

campylobacter jejuni, campylobactor coli: clinical presentations

A

more aggressive then salmonella gastroenteritis
incubation period of 1-7 days with initial flu like prodromal illness
sever abdominal pain that is often suspected to be appendicitis initially
self limiting

complications: severe local haemorrhage, reactive arthritis / guillain-barre syndrome (cross reactivity with self antigens giving rise to neurological symptoms)

42
Q

campylobacter jejuni, campylobacter coli: diagnosis

A

stool culture

43
Q

campylobacter jejuni, campylobacter coli: treatment

A

rehydration, erythromycin or ciprofloxacin for severe illness

prevention: eliminate from poultry farms, cook safely, pasteurize milk

44
Q

name the 2 helicobacter species:

A

helicobacter pylori, helicobacter cinaedi, helicobacter fennelliae

45
Q

helicobacter pylori: culture

A

grown under microaerophilic conditions at 37degc

46
Q

helicobacter pylori: character

A

urease positive, only infects gastric-type mucosa; can be found in duodenum/esophagus too due to gastric metaplasia

47
Q

helicobacter pylori: tranmission

A

faecal-oral, oral-oral

48
Q

helicobacter pylori: clinical presentations

A

symptoms develop after 2 weeks: abdominal pain, flatulence (accumulation of gas in the alimentary canal), nausea, bad breath

chronic active gastritis: provoked by bacterial antigens, causes non-ulcer dyspepsia and eventual atrophic gastritis

other implicated diseases: peptic ulcer disease (eradication of infection drops recurrence rate to zero); gastric adenocarcinoma; gastric mucosa-associated lymphoid tissue lymphoma (MALT lymphoma)

49
Q

helicobacter pylori: diagnosis

A

non-invasive:
urea breath test
faecel antigen test
serology

invasive: only done when risk of cancer is high; or in emergency situations
culture from gastric biopses taken through a fibre optic endoscope
rapid urease test (observe pH change)
bopsy - microscopy through histology

50
Q

helicobacter pylori: treatment

A

several agents are given to eradicate colonisation, with more complex regimes giving a higher clearance rate, long-term followup needed to ensure true cure

triple therapy: omeprazole + amoxicillin + clarithromycin

quadruple therapy: (when triple is ineffecitve/ high clarithromycin or metronidazole resistance)
omeprazole + bismuth subsalicylate + metronidazole + tetracycline

prevention: improved living conditions, careful disinfection of endoscopes to prevent nosocomial infections

51
Q

h. cinaedi, h. fennelliae: clinical presentations

A

proctitis in homosexual men, bacteraemia

microb (12 decks)

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