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Miscellaneous Bacterial Agents of Disease

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live in the oral cavity, intestinal tract, & perigenital regions of humans ... segment of small intestine near colon; adhere, burrow through mucus and multiply ... – PowerPoint PPT presentation

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Title: Miscellaneous Bacterial Agents of Disease


1
Miscellaneous Bacterial Agents of Disease
Chapter 21
2
spirochetes
  • Gram negative human pathogens
  • Treponema
  • Leptospira
  • Borrella

3
Treponema
  • thin, coiled cells
  • live in the oral cavity, intestinal tract,
    perigenital regions of humans animals
  • Pathogenic species are strict parasites

4
Treponema pallidum
  • human is the natural host
  • extremely fastidious sensitive, cannot survive
    long outside of the host
  • causes syphilis
  • Primary syphilis
  • Secondary syphilis
  • Tertiary syphilis
  • Congenital syphilis nasal discharge, skin
    eruptions, bone deformation, nervous system
    abnormalities
  • treatment penicillin G

5
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6
Chancre
7
Darkfield Microscopy
8
Leptospira
  • 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 targets kidneys, liver, brain, eyes
  • sudden high fever, chills, headache, muscle
    aches, conjunctivitis, vomiting
  • 50-60 cases a year in US

9
Borrella
  • large, 3-10 coils
  • Borrelioses transmitted by arthropod vector
  • B. hermsii - relapsing fever
  • B. burgdorferi - Lyme disease

10
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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12
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

13
Life Cycle of Ixodes
Figure 21.18
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15
Lyme disease
16
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
  • vaccine

17
Vibrio cholera
18
Action of Cholera Toxin
Figure 21.25
19
other Vibrio
  • salt-tolerant inhabitants of coastal waters,
    associate with marine invertebrates
  • Vibrio parahaemolyticus gastroenteritis from raw
    seafood
  • Vibrio vulnificus - gastroenteritis from raw
    oysters

20
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

21
Campylobacter jejuni
22
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
  • H. pylori produces numerous virulence factors
    that enable it to colonize the stomach

23
H. pylori and Peptic Ulcers
Figure 21.27.1
24
H. pylori and Peptic Ulcers
Figure 21.27.2
25
H. pylori and Peptic Ulcers
Figure 21.27.3
26
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

27
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

28
4 types of rickettsioses
  • epidemic typhus R. prowazekii carried by lice
    starts with a high fever, chills, headache, rash
    May have a chronic, recurrent form
  • endemic typhus R. typhi, harbored by mice
    rats occurs sporadically in areas of high flea
    infestation milder symptoms
  • Rocky Mountain spotted fever R. rickettsii
    zoonosis carried by dog wood ticks most cases
    on eastern seaboard distinct spotted rash may
    damage heart CNS
  • Ehrlichia genus contains 2 species of
    rickettsias tickborne bacteria cause human
    monocytic granulocytic ehrlichiosis

29
Rocky Mountain Spotted Fever
30
Rocky Mountain Spotted Fever Rickettsia
rickettsii
Distribution of cases over a 4-year period
31
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

32
Coxiella burnetti
33
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

34
Cat-scratch disease
Bartonella henselae
35
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

36
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

37
Chlamydia trachomatis
Lymphogranuloma venereum lesion
Trachoma
38
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

39
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

40
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41
Thin mucous coating of salivary proteins
Streptococcus mutans
Secondary invaders
42
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
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