Spirochetes
&
Gram Negative Cocci
Professor Sudheer Kher
1
Learning Objectives
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Enlist medically important GNCs & Spirochetes
List important virulence factors
Describe the mechanism of development of
infection by GNCs
List pathogenicity of meningococci & gonococci
List spirochetes and diseases caused by them
List Lab tests for diagnosis of syphilis
Resources - Ananthanarayan Ch 25, 42
Key Words
• Spirochete
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Axial filament
Treponema pallidum
Syphilis
Chancre
Primary lesion
Darkfield microscopy
Secondary Lesion
Tertiary Lesion
Anti-cardiolipin
antibodies VDRL/RPR
tests
• Borrelia burgdorferi
– Lyme disease
• Relapsing fever
• Vincent’s angina
• Leptospira (leptospirosis, Weil’s
Disease)
• Neisseria
– Thayer Martin medium
– N. gonorrhoeae
• Gonorrhea
– N. meningitidis
• Meningitis
• Fulminant meningococcemia 3
SPIROCHETES
Treponema, Borrelia and
Leptospira
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Spirochetes
• Gram negative
• Long, thin, helical, motile
• Axial filaments
– Locomotion
– Between peptidoglycan layer/outer membrane
* Runs parallel
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Treponema pallidum
• Transmission
 genital/genital
 in utero or during birth
• Pathogenicity
Syphilis
 Chronic, Slowly progressing
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• Primary lesion
- chancre
– 10 to 60 days
– area of ulceration & inflammation
– many organisms
• Secondary (2-10 weeks later)
systemic spread
flu-like symptoms
skin, particularly
many organisms
• Tertiary
several years later
rare
skin, central nervous system
delayed hypersensitivity
few organisms
control by immune response
Syphilis
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Microbiological diagnosis
• Not culturable
• Dark field microscopy
– Actively motile organisms
– Brightly lit against dark backdrop
– Light shines at an angle
– Reflected from thin organisms
– Enters objective
• Silver impregnation Fontana / Levaditi stain
• Fluorescence microscopy antibody staining
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Secondary and Tertiary Syphilis
- serology
• Screening method
• Antibodies to cardiolipin VDRL / RPR Tests
• False positive result possible
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Specific diagnosis
Antibodies to treponemal antigen TPHA
No false positives
Once positive remain so for many years.
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Borrelia burgdorferi and Lyme
disease
Lyme Disease
erythematous rash
Ixodes scapularis, tick vector for
Lyme disease. Also known as Ixodes
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dammini. CDC
Lyme disease - symptoms
• bacteremia
– acute
• arthritis
• cardiac
• neurologic
– chronic
* weeks, months later
A tick bite leads to transmission of B. burgdorferi
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Therapy
• Early antibiotic therapy
– Curable
* Penicillin
* Tetracycline
• Late antibiotic administration
– Ineffective
12
Diagnosis
A physicians dilemma
• Serum antibodies to B.
burgdorferi.
• Laboratory strains
– Grow extremely slowly
– Tissue culture media
– Not bacteriological
media
• Patient body fluids/tissue
sample
– Almost never growth
• Acute
– responds to
antibiotic
–antibodies not
detectable
• Late diagnosis
– not curable
– antibodies
detectable
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Relapsing fever
• Transmission
Diagnosis
Lice-B. recurrentis
 Human, primary host
•Immune response develops
•Fever disappears
•New antigens expressed
•No immunity
•Disease reappears
•No culture
•No
serological
test
•Detected blood smear
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Borrelia vincentii
• Extremely painful condition of oral
cavity
• Symbiotic infection with Fusobacterium
fusiformis
• Normal inhabitant of mouth
• Can cause Vincent’s Angina
Leptospirosis
Symptoms
–flu-like
–severe systemic disease
* Liver
* kidney
* Brain
* Eye
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Transmission
• Infected urine
– rodents
– farm animals
• Water
• Through broken skin.
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Laboratory Diagnosis
• Serology
• Most readily culturable of spirochetes
– culture still extremely difficult
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Neisseria
• Gram negative
• Diplococci (pairs of cocci)
• Oxidase positive
• Culture
• Thayer Martin.
– selective
– chocolate agar
* heated blood (brown)
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N. gonorrhoeae
the “Gonococcus"
• Exclusive disease of humans
• Gonorrhea
• Urethritis in men
• Endo-cervicitis in women
• Second most common venereal disease
• Ophthalmia neonatorum – Non venereal
transmission
• Crede’s prophylaxis – Silver nitrate eye
drops
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Smear
• Polymorphonuclear cell
• Gram negative cocci
– Many in cells
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Dissemination -gonococci
• Gonoccocal arthritis
– “septic” arthritis
• Dermatitis
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Antibiotic therapy
• β lactamase-resistant cephalosporin
– e.g. ceftriaxone
• resistant strains
– common
– produce β lactamases
– destroy penicillin
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Pathogensis
• Adhesion to genital epithelium
– Outer membrane
– Pili (Fimbrae)
*Antigenicity
highly variable among strains
• No vaccine
• IgA protease
– also N. meningitidis
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N. gonorrhoeae
• Tissue injury
– lipopolysaccharide
– peptidoglycan
• Only Fimbriated strains cause disease
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N. meningitidis
(the “Meningococcus")
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N. meningitidis
• Resides in humans only
• Usually sporadic cases
– mostly young children
• Outbreaks
– Adults
– Crowded conditions
*e.g. Army barracks, Dorms
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Neisseria meningitidis
Upper respiratory tract infection
– Adhesion pili
Bloodstream
Brain
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Meningococcal meninigitis
• Second most common meningitis
– pneumococcus, most common
• Fatal if untreated
• Responds well to antibiotic therapy
– penicillin
• Also causes fulminant Meningococcemia
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Fulminant meningococcal septicaemia
presents with:
Extensive haemorrhage into the
skin
Hypotension
Shock
Confusion
Coma
DIC
Death (within a few hours of the
onset of symptoms)
If adrenals are involved it is called as Waterhouse-Friderichsen Syndrome
(WFS)
Laboratory Diagnosis
• Spinal fluid
– Gram negative diplococci
within polymorphonuclear cells
– Meningococcal antigens by CIEP
• Culture
– Blood agar, Chocolate agar
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Virulence factor -Capsule
• Capsule
– inhibit phagocytosis
• Anti-capsular antibodies
– stop infection
•Antigenic variation
– sero-groups
• Vaccine
–multiple sero-groups
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