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Chapter 21
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Transcript

  • 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.
  • 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
  • 11.
  • 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 bull’s 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
  • 14.
  • 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.
  • 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