Microbiology - 0425 0426 0427 - Other Bacteria of Medical Importance

  1. Enterococcus faecalis
    where found
    drug resistant
    toxin & other products
    • G(+)
    • Facultative anaerobic
    • Found in intestines
    • Drug Resistant (VRE, Vancomycin)
    • No potent toxins
    • Produces cytolysin: inhibit the growth of other G(+)
    • found in patients w/ catheters, causes bacteremia, endocarditis, UTI, wound infection, endodontic infection (root-canal infection)
    • Treated w/ aminoglycoside antibiotic w/ cell wall activity: vancomycin, penicillin, ampicillin
  2. Endodontic infections
    • bacteria get to the root-canal via untreated cavity or dentinal tubules, or infected after root-canal treatment
    • Ef causes repeated endodontic infections
  3. Bacillus characterized by ______; O2 ____; G(?)
    • spore forming
    • aerobic
    • +
  4. B. anthracis causes _____, found ____ in ___ form.
    • anthrax
    • soil
    • endospore form in the environment
  5. Anthrax
    • usually disease of livestock
    • animal vaccination effective
    • human vaccine not widely spread (low risk, high toxicity)
  6. Inhalation anthrax
    used as bioweapon; inhaling the airborne spores
  7. Inhalation anthrax - symptoms
    • Flu-like sympotoms
    • non-productive coughs
    • fever/chills
    • muscle aches
    • malaise
  8. Inhalation anthrax - development and treatment
    • spores inhaled
    • in lungs, macrophage takes up the spore
    • Germination inside macrophage
    • Grow, rupture, released into bloodstream
    • CO2 in blood triggers the bacteria to produce toxin
    • may result in death in 3 days of symptoms
    • treat w/ ciprofloxacin (Cipro) -> DNA gyrase
  9. B. cereus
    found in
    • soil, air, water in endospore form
    • rice
    • food poisoning and ocular infections
  10. In cooked rice not refrigerated, B. cereus
    spores germinate
  11. Types of food poisoning caused by B. cereus
    • Emetic form: intoxication; by heat stable enterotoxin in contaminated rice. Duration of disease < 6hrs.
    • Diarrheal form: infection; by heat labile enterotoxin in contaminated meat, vegetables; loss of water via GI; lasts 20-36hrs.
    • No treatment needed
  12. Ocular infection caused by B. cereus
    • Physical injury of eye by tool contaminated w/ B. cereus
    • Loss of vision within 48hrs
    • Louis Braille
    • Treatment: vancomycin, clindamycin, ciprofloxacin, gentamycin
  13. Listeria monocytogenes - characteristics
    • G(+)
    • grow between 1-45 C
    • Causes listeriosis (food poisoning)
    • Intracellular pathogen;
    • ActA: uses actin as a tool to propel the bacterium from one cell to an adjacent cell.
  14. Listeriosis - source, impacted population, mortality, treatment
    • Outbreaks on chicken, turkey, vegetables/fruit
    • In neonates, elderly, immunocompromised
    • 20-30% mortality rate
    • treatment: ampicillin, penicillin, gentamycin
  15. Clostridium
    • G(+)
    • spore forming
    • strictly anaerobic
  16. C. perfringens
    • Present in soil, water, GI tract of human and animals
    • Food poisoning and gas gangrene (myonecrosis)
    • Twelve toxins - alpha toxin (lethal toxin, a phospholipase C) - lyses cells such as erythrocytes (massive hemolysis), leukocytes, platelets (bleeding), endothelial cells (increase vascular permeability) -> tissue damage
  17. Gas gangrene by Cp
    • after injury and inoculation -> travel to soft tissue -> necrosis
    • In muscle, produce gas (H2, CO2) -> expands muscle, cuts off blood supply -> myonecrosis
    • 40-100% mortality
    • Treatment: surgery - amputation of impactedc tissue/limb to prevent spread; high dose of penicillin
  18. C. difficile - disease
    • Antibiotic associated diarrhea, colitis
    • Induced by long period of antibiotic therapy for other purposes -> normal flora wiped out -> resistant and becomes dominant
    • emerging pathogen due to antibiotic abuse
    • treatment: discontinue implicated antibiotic; metronidazole is used to kill it
  19. Mycobacterium tuberculosis
    • Causes tuberculosis (tb)
    • discovered by Robert Koch
    • Very slow growing, can take about 5-8 weeks to grow on plates or in broth
    • Cell coat: not really G+ or G-, acid-fast staining
  20. tuberculosis - epidemiology
    • 15 million are infected in the US
    • Estimated that 20-40% of the population worldwide is infected; Mostly countries in Africa, Asia
    • Many of the people who are infected are foreigners or people who travel to other countries and come back
    • 2 million deaths per year
  21. acid-fast staining
    • Thick peptidoglycan above cytoplasmic membrane (like G+)
    • Structures outside peptidoglycan:
    • mycolic acid - responsible for acid-fast staining; about 70-90 carbons in length, contains cyclopropane structure; unlike the polysaccharide in LPS
    • Sugar molecules called arabinogalactan connect the mycolic acid structure to peptidoglycan
  22. Pathogenesis of tb
    • Respiratory pathogen engulfed by macrophage
    • Mt prevents fusion w/ lysosome and grows inside the phagosome
    • Macrophage secrets interleukin under the stim of Mt growth, recruits WBCs
    • Eventually encased by WBCs and becomes a granuloma
    • Can remain in this stage for years; dormant, aka latent infection, no symptoms
    • Under certain conditions (immunocompromise, etc.) becomes active and is released -> active tb
  23. Treatment of TB
    • Antibiotic cocktail over 6-9mo (slow growth; hidden by immune system)
    • Isoniazid -> cell wall synthesis
    • Rifampin -> RNA synthesis
    • Ethambutol -> cell wall synthesis
  24. Borrelia
    • G(-)
    • spirochete, has periplasmic flagella
  25. B. burgdorferic causes _________.
    • lyme disease (named after Old Lyme, CT)
    • No toxins or virulent factors identified
  26. Lyme disease
    • most prevalent tick-borne disease in US
    • Spread via deer tick (up to 50% deer ticks carry Bb; can be found in the environment, not necessarily directly from deer)
    • transmission occurs when tick takes bloodmeal (stays on skin 12-24hrs)
    • Symptoms:
    • Acute: headaches, chills, backache, fatigue, with large rash at site of infection (bull's eye; erythema migrans)
    • Chronic: weeks later; arthritis (40-60% patients), neurological involvement (15-20%), cardiac damage (8%); can be dormant in CNS for long time
    • Treatment: treated by tetracycline or penicillin early on.
  27. Treponema pallidum
    • spirochete
    • causes syphilis
    • sensitive to environment ( requires mucosal environment, can’t transfer through the air; Has to be through direct contact, as with most STDs; can't pass through unbroken skin, must break epidermal layer)
    • Can pass from mother to fetus during pregnancy; congenital syphilis
  28. Three stages of syphilis
    • Primary: multiplies at site of infection -> lesions; heals spontaneously
    • Secondary: spread to mucosal membranes, eyes, joints, bones, CNS -> extensive multiplication -> induce hypersensitivity reaction at site of infection, rash, all over the body
    • Tertiary: 50% reach this stage; infection of heart or CNS, inflammation -> can be fatal
    • Treatment: penicillin, 7-10d for primary and secondary, several weeks for tertiary
  29. Neisseria - G(?), shape
    -, coccus
  30. N. gonorrhoeae - causes, environment
    • gonorrhea
    • very sensitive to the environment - Easily killed in desiccation, varying temperatures, must live in mucous membranes in the genitourinary tract
  31. Gonorrhea - genders, newborns, treatment
    • Females- vaginitis (mild symptoms) -> untreated, lead to pelvic inflammatory disease -> can cause sterility
    • Males - painful infection of the urethral canal
    • In both males and females, if untreated, damage to the heart valves and joint tissues
    • Eye infections in newborns (Erythropoietin ointment applied to prevent)
    • Penicillin once wiped out the disease
    • penicillin resistant strains emerged in 1980s and is widespread
    • sensitive to beta-lactams - Cefixime, ceftriaxone
    • Quinolones (Cipro/ciprofloxacin)
  32. There is no vaccine or long term immunity for this bacterium due to
    antigenic switching - switch surface expression profile, new serotype (variant)
  33. Ng and oral contraceptives
    Oral contraceptives alter the local mucosal environments by increasing the vaginal pH to mimic pregnancy -> eliminates the lactic acid bacteria -> Ng becomes dominant
  34. N. meningitidis - causes, distribution
    • meningitis
    • 30% of people carry the bacterium as a natural inhabitant, healthy individuals, in the nasopharynx, no harmful effects, asymptomatic
  35. meningitis
    • inflammation of the meninges, the membrane surrounding the CNS
    • Occurs in epidemics -> in closed populations, eg military barracks, dorms
    • Since this pathogen can dry out, it requires close contact
    • Affects school age students and young adults
  36. meningitis - pathogenesis
    • Not known what triggers the bacteria into a pathogenic state
    • Respiratory pathogen, transmitted through air droplets-> Colonizes cells of nasopharynx -> enter bloodstream -> meninges
  37. meningitis - Symptoms, treatment
    • Headache
    • Vomiting
    • Stiff neck
    • can result in coma and death within hours
    • Vaccine in 2005, not long lasting (antigenic switching)
    • penicillin and chloramphenicol (no more used in US)
  38. Haemophilus influenzae - G(?), distribution, causes, genome
    • G-
    • found in almost all individuals
    • upper respiratory tract infections, otitis media in children, meningitis in children
    • First bacteria to have its genome sequenced in 1995
  39. Vaccine of Hi
    • HiB vaccine
    • very effective
    • acts against type B Hi, an encapsulated strain, very virulent, causes bacterial meningitis in kids
  40. Pseudomonas aeruginosa - G(?), distribution, characteristics, associated diseases
    • G(-)
    • Ubiquitous in nature, basically found everywhere (Opportunistic pathogen)
    • superbug with a lot of virulence factors, with highly resistant strain
    • the most common cause of death in CF patients
    • in lungs of cystic fibrosis patients, forms strong biofilms, secrets polysaccharide material, alginate, causes bacteria to become mucoid
    • Also associated with burns (w/o skin barrier), pneumonia, ear infections, eye infections, urinary tract infections (UTIs)
  41. Resistance of SA
    • very large genome
    • enCodes for all types of antibiotic pumps, contains plasmids, etc
  42. Therapy of Pseudomonas aeruginosa
    combination including beta-lactams
  43. Enterobacteria
    • Normal inhabitants of GI tract, can cause UTIs and food poisoning
    • Escherichia coli
    • Salmonella
    • Shigella
    • Proteus
    • Klebsiella
  44. Escherichia coli
    • Common inhabitant of inhabitant
    • Produces vitamin K
  45. Pathogenic strains of E. coli
    • O157:H7, Enterohemorrhagic E. coli, EHEC
    • O: O-antigen, types of sugars
    • 157: 157th O-antigen structure that was discovered
    • H7: the seventh type of flagella, based on genetic recombination
    • Enterotoxic E. coli, ETEC
  46. EHEC
    • toxins destroy intestinal lining
    • invades the kidneys -> lead to permanent renal damage. Leading cause of renal failure in children in the US
  47. ETEC
    • Causes traveller’s diarrhea
    • endemic in certain areas - native people are immune to the effects
    • resolved with fluids, not treated with antibiotics
  48. Salmonella - characteristic, causes, sources
    • >2500 different O-antigens
    • salmonellosis - food poisoning enteric disease -> fever -> systemic
    • found in eggs, meat, dairy products
  49. S. typhi
    Causes typhoid fever, relatively rare in the US
  50. S. typhimurium
    • More prominent in US
    • Transmitted by food handlers through unsanitary conditions - Fecal contamination
    • Treatment is not needed for this bacterial infection, usually self limiting
  51. Campylobacter jejuni - distribution, causes, pathogenesis, size, treatment
    • Lives in poultry, hogs
    • The most common foodborne illness in the US
    • use flagella to bind to the GI lining
    • can pass through 0.4 um filter
    • Usually self limiting, but antibiotics are used when there is a serious disease
  52. Vibrio cholerae - shape, causes
    • comma shaped, with a single polar flagellum
    • cholera, a Waterborne disease
    • endemic in Asia
  53. Bordetella pertussis - causes, transmission, pathogenesis, treatment
    • whooping cough/pertussis
    • transmits from person to person by coughing
    • pertussis toxin (A-B toxin) causes tissue damage - inactivates protein inhibits adenylate cyclase -> increase in cAMP -> increase in respiratory secretions and mucous production -> airway restriction, or pertussis
  54. pertussis - symptoms, treatment
    • characterized by aggressive repetitive cough that often results in vomiting in a cycle
    • DPT vaccine - lowered the incidence and severity of the disease
    • Macrolides - erythromycin, azithromycin
  55. Bordetella bronchiseptica
    • dog pathogen, Causes kennel cough in dogs
    • Similar to Bp - transmitted by air droplets, coughing
    • used as a model system to study the disease
    • Not really an animal model, but it’s a naturally occurring disease that mimics the human infection, very useful tool to use
  56. Corynebacterium diphtheriae - G(?), distribution, causes, transmission
    • G+
    • found in oropharynx and skin of healthy asymptomatic carriers
    • diphtheria
    • Transmitted by respiratory droplets
  57. Vaccine for diphtheria
    toxoid, the diphtheria toxin treated with formalin, Diphtheria toxin is the most important virulent factor
  58. diphtheria - Symptoms
    • Fever
    • Malaise
    • Sore throat
    • Thick pseudomembrane, covers tonsils & palate, consists of bacteria, lymphocytes, fibrin, dead cells, very characteristic purple, dark membrane in the back of the throat, occurs early, As a dentist, can see this before physicians
  59. diphtheria - pathogenesis, treatment
    • Toxin binds to heart cells and neurons via heparin receptor, and kills them (one molecule - one cell, Elongation Factor 2 receptor, protein synthesis, ...)
    • Bacteria doesn’t have to enter bloodstream
    • toxin has to enter bloodstream
    • Anti-toxin therapy: passive immunity to eliminate the toxin, follow up with either penicillin or erythromycin to clear out the bacteria
  60. Chlamydia - G(?), life style
    • G(-), no peptidoglycan has been detected in cell wall (genes exist but not expressed)
    • Obligate intracellular parasites
    • Elementary body: metabolically inactive, infectious, resistant to harsh conditions (not spore).
    • Reticulate body: metablically active, non-infectious.
  61. Pathogenesis of Chlamydia
    • Attaches and enters host cell
    • In phagosome, EB reorganize into RB
    • RB divides and grows
    • RB reorganize into EB
    • cell rupture and release EB "reverse endocytosis"
  62. C. trachomatis - causing, treatment
    • Trachoma -> blindness
    • most common STD in US
    • genital infection precedes eye infection
    • Urogenital infections - nongonococcal urethritis (NGU)

    doxycycline, azithromycin, erythromycin; hard to treat/reach
  63. Rickettsia rickettsii
    • Obligate intracellular
    • Transmitted by ticks, mites, lice, fleas, and rodents carry them
    • Causes Rocky mountain spotted fever
  64. Rocky mountain spotted fever - pathogenesis
    • attaches to host endothelial cells
    • phagocytosis
    • degrades phagosome membrane w/ phospholipase
    • grows & replicates in cytoplasm/nucleus of endothelial cells
    • damages blood vessel lining cells -> leakage of blood vessels
    • hypovolemia & hypoproteinemia due to loss of plasma from blood into tissue
    • organ failure
  65. Rocky mountain spotted fever - symptoms, treatment
    • Have to be exposed to ticks for more than 6 hrs; painless bite.
    • Symptoms develop in 2-14d
    • High fever, headache, "spotted" rash on wrists, arms, chest, ankles (leakage of blood vessels)
    • Tetracycline
Card Set
Microbiology - 0425 0426 0427 - Other Bacteria of Medical Importance
Microbiology - 0425, 0426, 0427 - Other Bacteria of Medical Importance