The Spirochetes

1
The Spirochetes

• Gram-negative human pathogens
• Free living saprobes, or commensals of animals,
  not primary pathogens
• Treponema
• Leptospira
• Borrelia

2
Typical spirochete
3
Genus Treponema

• Thin, regular, coiled cells
• Live in the oral cavity, intestinal tract, and
  perigenital regions of humans and animals
• Pathogens are strict parasites with complex
  growth requirements
• Require live cells for cultivation

4
Treponema Pallidum The Spirochete of Syphilis

• Humans are the natural host
• Extremely fastidious and sensitive cannot
  survive long outside of the host
• Sexually transmitted and transplacental

5
Pathogenesis and Host Response

• Spirochete binds to epithelium (mucous membrane
  or abraded skin), multiplies, and penetrates
  capillaries
• Moves into circulation and multiplies
• Untreated syphilis marked by 3 clinical stages
• Primary, secondary, tertiary
• Spirochete appears in lesions and blood during
  first 2 stages communicable

6

• Primary syphilis appearance of hard chancre at
  site of inoculation chancre heals spontaneously
• Secondary syphilis fever, headache, sore
  throat, red or brown rash on skin, palms, and
  soles rash disappears spontaneously
• Tertiary syphilis about 30 of infections enter
  in tertiary stage can last for 20 years or
  longer numerous pathologic complications occur
  in susceptible tissues and organs
• Neural, cardiovascular symptoms, gummas develop
• Congenital syphilis nasal discharge, skin
  eruptions, bone deformation, nervous system
  abnormalities

7
(No Transcript)
8
Primary syphilis lesion, chancre
9
Symptom of secondary syphilis
10
Manifestations of syphilis
11
Congenital syphilis
12
Diagnosis and Treatment

• Stages of syphilis mimic other diseases
• Consider symptoms, history, microscopic, and
  serological testing
• RPR, VDRL, FTA-ABS
• Treatment penicillin G

13
Treponema pallidum
14
Nonsyphilitic Treponematoses

• Resemble syphilis rarely transmitted sexually or
  congenitally cutaneous and bone diseases endemic
  to specific regions
• Bejel T. pallidum subspecies endemicum
  deforming childhood infection of the mouth, nasal
  cavity, body, and hands
• Yaws T. pallidum subspecies pertenue invasion
  of skin cut, causing a primary ulcer that seeds a
  second crop of lesions
• Pinta T. carateum superficial skin lesion that
  depigments and scars the skin

15
Endemic treponematoses
16
Leptospira and Leptospirosis

• Tight, regular individual coils with a bend or
  hook at one or both ends
• L. biflexa harmless, free-living saprobe
• L. interrogans causes leptospirosis, a zoonosis
• Bacteria shed in urine infection occurs by
  contact with contaminated urine targets kidneys,
  liver, brain, eyes
• Sudden high fever, chills, headache, muscle
  aches, conjunctivitis, and vomiting
• Long-term infections may affect kidneys and liver
• 50-60 cases a year in U.S.

17
Borrelia Arthropod-Borne Spirochetes

• Large, 3-10 coils irregularly spaced
• Borrelioses transmitted by arthropod vector
• B. hermsii relapsing fever
• B. burgdorferi Lyme disease

18
B. Hermsii Relapsing Fever

• Mammalian reservoirs squirrels, chipmunks, wild
  rodents
• Tick-borne
• After 2-15-day incubation, patients have high
  fever, shaking, chills, headache, and fatigue
• Nausea, vomiting, muscle aches, abdominal pain
  extensive damage to liver, spleen, heart,
  kidneys, and cranial nerves
• Parasite changes and immune system tries to
  control it Recurrent relapses
• Tetracycline

19
Pattern in relapsing fever
20
B. Burgdorferi Lyme Disease

• Carried by white-footed mouse, transmitted by
  Ixodes ticks
• Complex 2-year cycle involving mice and deer
• Nonfatal, slowly progressive syndrome that mimics
  neuromuscular and rheumatoid conditions
• 50-70 get bulls eye rash
• Fever, headache, stiff neck, and dizziness
• If untreated can progress to cardiac and
  neurological symptoms, polyarthritis
• Tetracycline, amoxicillin
• Vaccine for dogs, human vaccine discontinued
• Insect repellant containing DEET

21
Cycle of Lyme disease
22
Views of Lyme disease skin rash
23
Curviform Gram-Negative Bacteria and Enteric
Diseases

• Three genera
• Vibrio comma-shaped rods, single polar
  flagellum
• Campylobacter short spirals or curved rods one
  flagellum
• Helicobacter spirochete with tight spirals and
  several polar flagella

24
Vibrio Cholera

• Comma-shaped, possess unique O and H Ags
• El Tor biotype survives longer, more infectious
• Infectious dose 108
• Infects mucous barrier of small intestine,
  noninvasive
• Cholera toxin causes electrolyte and water loss
  through secretory diarrhea, rice water stool
  resulting dehydration leads to muscle,
  circulatory, and neurological symptoms
• Treatment oral rehydration, tetracycline
• Vaccine available

25
Alterations in intestinal function caused by
cholera toxin
26
Alterations in intestinal function caused by
cholera toxin
27
Pathogens Carried by Seafood

• Salt-tolerant inhabitants of coastal waters,
  associate with marine invertebrates
• Vibrio parahaemolyticus gastroenteritis from
  raw seafood symptoms similar to cholera
• Vibrio vulnificus gastroenteritis from raw
  oysters serious complications in persons with
  diabetes or liver disease
• Treatment fluid and electrolyte replacement
  occasionally antimicrobials

28
Diseases of the Campylobacter Vibrios

• Campylobacters slender, curved, or spiral
  bacilli, often S-shaped or gull-winged pairs
• Polar flagella
• Common residents of the intestinal tract,
  genitourinary tract, the oral cavity of birds and
  mammals
• Most important
• Campylobacter jejuni
• C. fetus

29
Campylobacter Jejuni Enteritis

• Important cause of bacterial gastroenteritis
• Transmitted by beverages and food
• Reach mucosa at the last segment of small
  intestine near colon adhere, burrow through
  mucus and multiply
• Heat-labile enterotoxin CJT stimulates a
  secretory diarrhea like that of cholera
• Symptoms of headache, fever, abdominal pain,
  bloody or watery diarrhea
• Treatment with rehydration and electrolyte
  balance therapy

30

• Campylobacter fetus opportunistic pathogen that
  infects debilitated persons or women late in
  pregnancy
• Meningitis, pneumonia, arthritis, septicemia in
  the newborn

31
Helicobacter Pylori Gastric Pathogen

• Curved cells discovered in 1979 in stomach
  biopsied specimens
• Causes 90 of stomach and duodenal ulcers
  apparent cofactor in stomach cancer
• People with type O blood have a 1.5-2X higher
  rate of ulcers
• Produces urease which converts urea into ammonium
  and bicarbonate

32
The causative agent of stomach ulcers
33
Medically Important Bacteria of Unique Morphology
and Biology
34
Family Rickettsiaceae

• Contains about 23 species of pathogens, mainly in
  the genus Rickettsia
• Cause diseases called rickettsioses
• All are intracellular parasites requiring live
  cells for cultivation
• Spend part of their life cycle in arthropod
  vectors
• Rickettsioses are important emerging diseases

35
Rickettsia

• Obligate intracellular parasites
• Gram-negative cell wall
• Among the smallest bacteria
• Nonmotile pleomorphic rods or coccobacilli
• Ticks, fleas, and lice are involved in their life
  cycle
• Bacteria enter endothelial cells and cause
  necrosis of the vascular lining vasculitis,
  vascular leakage, and thrombosis

36
Specific Rickettsioses

• Epidemic typhus R. prowazekii carried by lice
  starts with a high fever, chills, headache, rash
  Brill-Zinsser is a chronic, recurrent form
• Endemic typhus R. typhi, harbored by mice and
  rats occurs sporadically in areas of high flea
  infestation milder symptoms
• Rocky Mountain spotted fever R. rickettsii
  zoonosis carried by dog and wood ticks most
  cases in Southeast and on eastern seaboard
  distinct spotted rash may damage heart and CNS
• Ehrlichia genus contains 2 species of
  rickettsias tick-borne bacteria cause human
  monocytic and granulocytic ehrlichiosis

37
(No Transcript)
38
Trends in infection for Rocky Mountain spotted
fever
39
Transmission cycle in Rocky Mountain spotted
fever
40
Rash in RMSF
41
Related to the Rickettsioses

• Coxiella burnetti
• Bartonella sp.

42
Coxiella Burnetti

• Causes Q fever
• Intracellular parasite
• Produces an unusual resistant spore
• Harbored by a wide assortment of vertebrates and
  arthropods
• Infectious material includes urine, feces, milk,
  and airborne particles
• Usually inhaled causing pneumonitis, fever,
  hepatitis
• Tetracycline treatment
• Vaccine available

43
Bartonella Species

• Small gram-negative, fastidious, cultured on
  blood agar
• Cause
• Trench fever, spread by lice
• Cat-scratch disease, a lymphatic infection
  associated with a clawing injury by cats
• Bacillary angiomatosus in AIDS patients
• Tetracycline, erythromycin, and rifampin

44
Cat-scratch disease
45
The Chlamydiaceae

• Obligate intracellular parasites
• Small, gram-negative cell wall
• Alternate between 2 stages
• Elementary body small metabolically inactive,
  extracellular, infectious form released by the
  infected host
• Reticulate body noninfectious, actively
  dividing form, grows within host cell vacuoles

46
Life cycle of Chlamydia
47
Chlamydia Trachomatis

• Human reservoir
• 2 strains
• Trachoma attacks the mucous membranes of the
  eyes, genitourinary tract, and lungs
• Ocular trachoma severe infection, deforms
  eyelid and cornea, may cause blindness
• Inclusion conjunctivitis occurs as baby passes
  through birth canal prevented by prophylaxis
• STD second most prevalent STD urethritis,
  cervicitis, salpingitis (PID), infertility,
  scarring
• Lymphogranuloma venereum disfiguring disease of
  the external genitalia and pelvic lymphatics

48
The pathology of primary ocular chlamydial
infection
49
Diagnosis of chlamydial infection
50
Chlamydophila A New Genus

• Contains members that used to be members of genus
  Chlamydia
• Chlamydophila pneumoniae causes an atypical
  pneumonia that is serious in asthma patients
• C. psittaci causes ornithosis, a zoonosis
  transmitted to humans from bird vectors highly
  communicable among all birds pneumonia or
  flulike infection with fever, lung congestion

51
Molliculites and Other Cell-Wall-Deficient
Bacteria

• Called mycoplasmas
• Naturally lack cell walls, highly pleomorphic
• Require special lipids from host membranes
• Treated with tetracycline, erthyromycin
• M. pneumoniae primary atypical pneumonia
  pathogen slowly spreads over interior respiratory
  surfaces, causing fever, chest pain, and sore
  throat
• M. genitalium and Ureplasma urealyticum weak
  sexually transmitted pathogens

52
The morphology of mycoplasmas
53
Bacteria That Have Lost Their Cell Walls

• Exposure to certain drugs or enzymes can result
  in cell wall-deficient bacteria called L forms or
  
• L-phase
• Induced or occur spontaneously
• May be involved in some chronic diseases
• L- phase variants of group A streptococci,
  Proteus, and Corynebacterium, Mycobacterium avium
  paratuberculosis