Miscellaneous Bacterial Agents of Disease

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Miscellaneous Bacterial Agents of Disease
Chapter 21
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spirochetes

• Gram negative human pathogens
• Treponema
• Leptospira
• Borrella

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Treponema

• thin, coiled cells
• live in the oral cavity, intestinal tract,
  perigenital regions of humans animals
• Pathogenic species are strict parasites

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Treponema pallidum

• human is the natural host
• extremely fastidious sensitive, cannot survive
  long outside of the host
• causes syphilis
• Primary syphilis chancre lesion
• Secondary syphilis spread throughout the body
  via blood stream
• Latent syphilis obvious symptoms disappear
• Tertiary syphilis Hyperimmune response that can
  affect many systems. (dementia, blindness, heart
  disease etc. etc.)
• Congenital syphilis infection across the
  placenta-nasal discharge, skin eruptions, bone
  deformation, nervous system abnormalities
• treatment penicillin G

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Chancre
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Darkfield Microscopy
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Leptospira

• tight, regular individual coils with a bend or
  hook at one or both ends
• L. interrogans causes leptospirosis, a zoonosis
• bacteria shed in urine infection occurs by
  contact targets kidneys, liver, brain, eyes
• sudden high fever, chills, headache, muscle
  aches, conjunctivitis, vomiting
• 50-60 cases a year in US

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Borrelia

• large, 3-10 coils
• Borrelioses transmitted by arthropod vector
• B. hermsii tick-borne relapsing fever
• There also a louse-borne relapsing fever (B.
  recurrentis)
• B. burgdorferi - Lyme disease

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B. hermsii - relapsing fever

• mammalian reservoirs squirrels, chipmunks, wild
  rodents
• tick-borne
• after 2-15-day incubation, patients have high
  fever, shaking, chills, headache, fatigue
• nausea vomiting, muscle aches, abdominal pain
  extensive damage to liver, spleen, heart,
  kidneys, cranial nerves
• parasite changes immune system tries to control
  it- recurrent relapses
• tetracycline

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B. burgdorferi - Lyme disease

• transmitted by ticks
• complex 2-year cycle involving mice deer
• nonfatal, slowly progressive syndrome that mimics
  neuromuscular rheumatoid conditions
• 70 ? get bulls eye rash
• fever, headache, stiff neck, dizziness
• if untreated can progress to cardiac
  neurological symptoms, polyarthritis
• tetracycline, amoxicillin
• vaccine for dogs, human vaccine discontinued
• Prevention-insect repellant containing DEET

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Lyme Disease
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Lyme disease
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Vibrio cholera

• comma-shaped
• One of top 7 causes of morbidity mortality
• ingested with food or water
• infects surface of small intestine, noninvasive
• cholera toxin causes electrolyte water loss
  through secretory diarrhea (rice-water stool),
  resulting dehydration leads to muscle,
  circulatory, neurological symptoms
• treatment oral rehydration, tetracycline

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Cholera in Haiti

• 1,186 dead from cholera, 19,646 hospitalized (as
  of November 20th, 2010)

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Action of Cholera Toxin
Figure 21.25
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other Vibrio

• salt-tolerant inhabitants of coastal waters,
  associate with marine invertebrates
• Vibrio parahaemolyticus gastroenteritis from raw
  seafood
• Vibrio vulnificus
• gastroenteritis from raw oysters
• nasty skin/tissue infections of cuts and
  scratches

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Campylobacter jejuni

• important cause of bacterial gastroenteritis
• transmitted by beverages food (poultry most
  common)
• reach mucosa at the last segment of small
  intestine near colon adhere, burrow through
  mucus and multiply
• symptoms of headache, fever, abdominal pain,
  bloody or watery diarrhea that is self-limiting
• heat-labile enterotoxin

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Campylobacter jejuni
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Helicobacter pylori

• Curved cells discovered in 1979 in stomach
  biopsied specimens
• Slightly helical, highly motile bacterium that
  colonizes the stomach of its hosts
• Causes gastritis and most (if not all) peptic
  ulcers. (Also a big risk factor for stomach
  cancer)

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H. pylori and Peptic Ulcers
Figure 21.27.1
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H. pylori and Peptic Ulcers
Figure 21.27.2
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H. pylori and Peptic Ulcers
Figure 21.27.3
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Diagnosis, Treatment, and Prevention

• Diagnosis
• Presence of H. pylori can be demonstrated by a
  positive urease test
• Biochemical tests provide a definitive
  identification
• Treatment
• Antimicrobial drugs are used in combination with
  drugs that inhibit acid production
• Prevention
• Prevention involves good hygiene, adequate sewage
  treatment, water purification, and proper food
  handling

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Rickettsia

• obligate intracellular parasites
• gram-negative cell wall
• among the smallest bacteria
• nonmotile pleomorphic rods or coccobacilli
• ticks, fleas louse are involved in their life
  cycle
• bacteria enter endothelial cells cause necrosis
  of the vascular lining vasculitis, vascular
  leakage thrombosis
• treat with tetracycline chloramphenicol

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Types of rickettsioses

1. epidemic typhus R. prowazekii carried by lice
   starts with a high fever, chills, headache, rash
   May have a chronic, recurrent form
2. endemic typhus (murine typhus) R. typhi,
   harbored by mice rats occurs sporadically in
   areas of high flea infestation milder symptoms
3. Rocky Mountain spotted fever R. rickettsii
   zoonosis carried by dog wood ticks most cases
   on eastern seaboard distinct spotted rash may
   damage heart CNS
4. Ehrlichia genus human monocytic ehrlichiosis
5. Anaplasma genus anaplasmosis

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Rocky Mountain Spotted Fever
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Rocky Mountain Spotted Fever Rickettsia
rickettsii
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Coxiella burnetti

• causes Q fever
• intracellular parasite
• produces an unusual resistant spore
• harbored by a wide assortment of vertebrates
  arthropods
• transmitted by air, dust, unpasteurized milk,
  ticks
• usually inhaled causing pneumonitis, fever,
  hepatitis
• tetracycline treatment
• vaccine available

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Coxiella burnetti
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Bartonella

• small gram-negative, fastidious, cultured on
  blood agar
• Bartonella-caused diseases
• trench fever, spread by lice
• cat-scratch disease, a lymphatic infection
  associated with a clawing injury by cats.
• Organism carried by 40 of cats
• Most infections localized and resolve a a couple
  weeks
• bacillary angiomatosus in AIDS patients
• tetracycline, erythromycin rifampin

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Cat-scratch disease
Bartonella henselae
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Chlamydia

• obligate intracellular parasites
• small gram-negative cell wall
• C. 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

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Chlamydia trachomatis

• human reservoir
• 2 strains
• trachoma strain attacks the mucous membranes of
  the eyes, genitourinary tract lungs
• ocular trachoma uncommon in U.S. but common in
  Africa and Asia. Severe infection, deforms eyelid
  cornea, may cause blindness
• inclusion conjunctivitis occurs as babies pass
  through birth canal prevented by prophylaxis
• STD urethritis, cervicitis, salpingitis
  (PID),infertility, scarring
• lymphogranuloma venereum strain disfiguring
  disease of the external genitalia pelvic
  lymphatics

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Chlamydia trachomatis
Lymphogranuloma venereum lesion
Trachoma
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Mycoplasma

• naturally lack cell walls, highly pleomorphic
• treated with tetracycline, erthyromycin
• M. pneumoniae primary atypical pneumonia
  pathogen slowly spreads over interior respiratory
  surfaces, causing fever, chest pain sore
  throat.
• M. hominis Ureplasma urealyticum weak
  sexually transmitted pathogens

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Bacteria in dental disease

• oral cavity is a complex, dynamic ecosystem,
  containing 400 species
• dental caries slow progressive infection of
  irregular areas of enamel surface
• begins with colonization by slime-forming species
  of Streptococcus cross adherence with
  Actinomyces
• process forms layer of thick, adherent material
  (plaque) that harbors masses of bacteria which
  produce acid that dissolves enamel
• If plaque is allowed to stay, secondary invaders
  appear Lactobacillus, Bacteroides,
  Fusobacterium, Porphyromonas, Treponema.
• Acid dissolves tooth enamel

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Thin mucous coating of salivary proteins
Streptococcus mutans
Secondary invaders
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Peridontal disease

• soft tissue disease
• when plaque becomes calcified into calculus above
  and below the gingiva
• this irritates tender gingiva causing
  inflammation gingivitis
• pockets between tooth gingiva are invaded by
  bacteria (spirochetes gram-negative bacilli)
• tooth socket may be involved (peridontitis)
• tooth may be lost