Transcript Neisseria-spirochetes

Spirochetes and Neisseria
(Gram negative)
Lecture 36
Faculty: Dr. Alvin Fox
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Key Words
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Spirochete
Axial filament
Treponema pallidum
Syphilis
Chancre
Primary lesion
Darkfield microscopy
Secondary Lesion
Tertiary Lesion
Anti-cardiolipin antibodies
Anti-treponemal antibodies
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Borrelia burgdorferi
Lyme disease
Relapsing fever (other borrelia)
Leptospira (leptospirosis)
Neisseria
Thayer Martin agar
Oxidase test
N. gonorrhoeae
Gonorrhea
N. meningitidis
Meningitis
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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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www.orl.cz/choroby/ustni/jazyk/zanet/1
Histology: Treponema pallidum
- testis infected rabbit
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Treponema pallidum
• transmission
– genital/genital
– in utero or during birth
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Syphilis
• chronic
• slowly progressive
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• Secondary (2-10
- systemic spread
- flu-like symptoms
- skin, particularly
- many organisms
- Highly infectious
weeks later)
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• Tertiary
– several years later
– rare
– skin
– central nervous system
– delayed hypersensitivity
– few organisms
* control by immune response
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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
• conventional light microsrcopy
– light shines through
– NOT visualized
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• fluorescence microscopy
– antibody staining
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Secondary and Tertiary Syphilis
- serology
• screening method
• antibodies to cardiolipin
• specific diagnosis
• antibodies to treponemal antigen
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Autoimminty
• cardiolipin
– self antigen
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• no vaccine
• antibiotics (e.g. penicillin)
– effective
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Other treponemal diseases
• bejel, yaws and pinta
– extremely rare in US
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Borrelia burgdorferi and Lyme
disease
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Ixodes scapularis, tick vector for Lyme disease.
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Also known as Ixodes dammini. CDC
Lyme disease - symptoms
• bacteremia
– acute
• arthritis
• cardiac
• neurologic
– chronic
* weeks, months later
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Therapy
• early antibiotic therapy
– curable
* penicillin
* tetracycline
• late antibiotic administration
– ineffective
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Diagnosis
• serum antibodies to B. burgdorferi.
• laboratory strains
– grow extremely slowly
– tissue culture media
– not bacteriological media
• patient body fluids/tissue sample
– almost never growth
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A physicians dilemma
• acute
– responds to antibiotic
–antibodies not detectable
• late diagnosis
– not curable
– antibodies detectable
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Lyme Disease -etiology
• reactive arthritis similar to
– Reiter's syndrome
– rheumatic fever
• resembles rheumatoid arthritis
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Relapsing fever
• <100/ per year in US
• transmission
–tick-B. hermsii
* rodent, primary host
– lice-B. recurrentis
* human, primary host
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“Relapsing” fever
• immune response develops
– disease relapses
• new antigens expressed
– no immunity
– disease reappears
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Diagnosis
• no culture
• no serological test
• detected - blood smear
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Leptospirosis
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Leptospirosis
• <100 cases per year in US
• symptoms
–flu-like
–severe systemic disease
* 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
Neisseria gonorrhoeae
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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"
• found only in man
• gonorrhea
• second most common venereal disease
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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
*Antigenicity
highly variable among strains
• no vaccine
• IgA protease
– also N. meningitidis
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N. gonorrhoeae
• Tissue injury
– lipopolysaccharide
– peptidoglycan
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N. meningitidis
(the “Meningococcus")
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N. meningitidis
• resides in man 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
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Laboratory Diagnosis
• spinal fluid
– Gram negative diplococci
within polymorphonuclear cells
– meningococcal antigens
• Culture
– Thayer Martin agar
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Capsule
• capsule
– inhibit phagocytosis
• anti-capsular antibodies
– stop infection
•antigenic variation
– sero-groups
• vaccine
–multiple sero-groups
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