Microbio Exam 5

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Microbio Exam 5
2012-05-09 01:21:25

Microbio 265 Exam 5
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  1. Epidermis 2
    • Mucous memb.
    • a. wet, not as tough as skin
    • b. often low pH
    • c. Normal flora
    • d. macrophages, IgA
    • e. mucous
  2. Staphylococcus aureus and other staph species
    • a. Gm+ cocci in clusters
    • b. facultative metabolism
    • c. colonies 2-3mm. opaque with non-water soluble golden pigment +/- hemolysis
  3. Staphylococcus aureus #2
    • d. vir and inv factors numerous (examples
    • 1. coagulase (clots fibrinogen)
    • 2. enterotoxins (food poisoning)
    • 3. hyaluronidase (breaks down extracellular matrix)
    • 4. cytotoxins (kill WBC's)
    • 5. exfoliative toxins (skin peeling)
    • 6. others
    • 7. and other staph species are normal flora of skin, GI tract, oropharynges and urogenital tract
  4. Note: the virulence of a particual specimen and disease it causes depend on which vir factors the strain possesses
  5. Staphylococcus aureus and other staph
    A. Wound infections
    B. in-dwelling catheter infection
    • A. Wound infection
    • 1. autoinoculation or from fomites or hands
    • 2. Coagulase + or - staph
    • 3. can be MDR staph (eg. MRSA)
    • 4. may require aggressive antibiotic treatment
    • 5. can cause systemia
    • B. in-dwelling catheter infection
    • 1. catheters allow constant contact tof skin to open tissues leading to infection
    • 2. coagulase - staph, skin normal flora
    • 3. often causes low grade bacteremia
  6. Staph continued
    • furunucles: infections which start in hair follicle (rare cause of systemia)
    • carbuncle: infection is larger, deeper and more serious (must drain and treat with antibiotic)
    • pustules: a small lesion filled with pus (usually self-lmiting with drainage)
  7. Staph continued
    Staph skin diseases of newborn or children
    • 1. Scalded skin syndrome
    • a. neonates
    • b. staph stain with exfoliative toxin
    • c. erythema that starts in mouth and covers body in 2 days
    • d. top layer of skin peels
    • e. neonate recovers in about 2wks when IR kicks in
    • f. rare secondary systemia can kill in 36 hrs.
  8. Staph cont
    Staph skin diseases of newborn cont
    • 2. Impetigo (children, esp. boys)
    • a. staph strain with hyaluronidase vir. factor
    • b. superficial, rapidly spreading, contagious skin lesions, esp. of face.
    • c. heals without scarring
    • d. neonatal version: bullous impetigo
    • e. also Streptococcus pyogenes
  9. Staph cont
    toxic shock syndrome
    • 1. TSST-1 toxin producing strains of S. aureus
    • 2. systemia or from super absorbent tampons (no longer on the market)
    • 3. entire body desquamation
    • 4. rapidly fatal systemic shock if not treated
    • Staph. aureus an also cause endocarditis, systemia and food poisoning (later)
  10. Staph cont
    3. Sources of infection
    • a. autoinoculation from skin, GI or nasopharyngeal normal flora
    • b. fomites, droplet nuclei and hands cause many nosocomial infections
  11. Staph cont
    4. Treatment
    • a. Multiple drug resistance (MDR) is common (due to bacteriophage transduction?)
    • b. Methicillin resistant S. aureus (MRSA) now common in hospital environment and becoming common outside hospital.
    • c. Vancomycin resistant S. aureus (VRSA) has now been detected
  12. Streptococcal skin infections
    1. intro
    • a. Strept pyogenes and other streptococci cause a variety of diseases.
    • d. S. pyogenes can be carried transiently, in low numbers, with the normal flora in the nasopharynges
    • e. disease spread is most commonly from transient carriers in the form of droplet nuclei, hands, fomites
  13. Strept skin infections
    2. skin diseases
    A. pyoderma
    • 1. introduction of mo into broken skin
    • 2. pustule develops, usually self-limiting
  14. Streptococcal skin infections
    2. skin diseases
    b. erysipelas
    • 1. secondary to strept throat or pyoderma
    • 2. skin raised, inflamed, painful, low grade symptoms of systemia
  15. Strep skin infections
    c. cellulitis
    • 1. secondary to streopt throat or pyoderma
    • 2. a deeper infection than erysipelas
    • 3. skin not raised,but is inflamed, painful, symptoms of systemia
    • 4. many organisms can cause cellulitis
  16. Strep skin infections
    d. impetigo
    e. necrotizing fasciitis (flesh eating virus)
    • 1. introduced through skin break
    • 2. initially like cellulites, spreads to muscle and fat and degrades theses tissues with enzymes (vir factors)
    • 2. rapidly fatal systemia develps w/o aggressive treatment
  17. Other skin diseases that can also be caused by fungi and viruses
    • Small Pox
    • Dermatomycosis
  18. Burn infections
    • many mo's can cause burn infections
    • 1. coliforms (Gm-, facultative rods from GI)
    • 2. Staph and Strep
    • 3. Most common and dangerous: Pseudomonas aeruginosa
  19. Pseudomonas aeruginosa characteristics
    • 1. Gm-, aerobic rod
    • 2. found in water, soil, sometimes as GI normal flora
    • 3. extremely antibiotic and disinfectant resistant
    • 4. an opportunist but once it starts, a very serious infection ensues
    • 5. often makes blue and green pigments
    • 6. makes a wide variety of vir and inv factors that are very good at breaking down tissue and spreading the infection
  20. course of Pseudomonas burn infection
    • 1. autoinoculation or introduction from environment (soil, water, disinfectants, flowers, air, soapy water, hands)
    • 2. mo divides rapidly in weepage from burns
    • 3. hydrolytic enzymes allow easy tissue invasion
    • 4. fatal systemia, pneumonia follows (2-4wks)
  21. Treatment of Pseudomonas burn infection
    • 1. strict isolation/aseptic procedures to prevent infection
    • 2. antibiotic treatment difficult (combination therapy)

    e. Pseudomonas is also noted for Cystic Fibrosis pneumonia.
  22. Area of eye that can become infected
    • eyelid
    • conjuctiva
    • cornea
  23. protection of the eyes
    • 1. cornea/sclera are tough walled
    • 2. tears wash away mo's
    • 3. tears contain lysozyme
    • 4. mucous entraps mo's
    • 5 IgA is likely present
  24. Eye infection
    1. Chlamydia trachomatis
    • a. Obligate intracellular bacteria
    • b. causes a conjuctivitis called Trachoma
    • c spread by poor sanitation, flies, and the rubbing of eyes
    • d. highly contagious
    • e. lack of treatment leads to abraion of cornea by eyelid/lashes that then causes blindness (common cause of blindnes in 3rd world)
  25. Eye infection diseases
    2. Neisseria gonorrhoeae
    • a. Gm- intracellular bacteria
    • b. causes a disease in neonates called gonococcal conjuctivitis
    • c. infection occurs during vaginal birth in a mother with gonorrhea
    • d. lack of treatment leads to blindness
    • e. neonates are given prophylactic antibiotic eye drops at birth to prevent
  26. Eye infections
    3. Haemophilus influenzae biotype aegyptius
    • a. Gm- small rods
    • b. causes a disease called contact conjuctivitis or pinkeye
    • c. spread by poor sanitation, flies and the rubbing of eyes
    • d. highly contagious
  27. Pseudomonas spp infections
    • infections caused by overly long term use of soft contact lenses
    • several different viral conjunctivitis'
    • protozoal eye infection caused by ancanthamoeba keratits
  28. Bacterial diseases of the Circulation and Lymphatic systems
    • Closed system
    • 1. oxygenates tissues
    • 2. eliminate CO2
    • 3. remove wasts from tissues and deliver them to spleen and kidneys
    • 4. provide mobility to immune system, hormones and other chemical signals
    • 5. maintain temp homeostasis
  29. Lymphatic system
    • (open system)
    • 1. pick up lymph from interstitial spaces
    • 2. clear lymph before it is returned to circ.
    • 3. system has no pump
  30. Protection of the circ and lymph systems
    • 1. sterile
    • 2. 1st, 2nd and 3rd levels of immunity
    • 3. filtration of lymph by lymph nodes and blood by spleen
  31. Cardiac Diseases
    1. Subacute bacterial endocarditis (SBE)
    • a. slow onset of symptoms: fever, weakness,heart murmur
    • b. caused by oral streptococci and others from infections throughout the body (e.g. tooth infection, tonsillectomy, body piercings, gynecological exam, teeth cleaning, flossing or even brushing teeth)
    • c. often patient has a previous lesions of the heart which provide tissue for the bacteria to entangle in (e.g. causes include scarlet fever, syphilis, previous SBE or heart deformities)
    • d. slowly fatal if not treated (long term antibiotics)
  32. Diagnosis of (SBE)
    • 1. imaging of mass in hearat
    • 2. blood culture
    • a. draw blood into broth filled bottle, incubate
    • b. requires many bottles because: unknown mo metabolic requirements (O2, nutrients), interfereing chems, antibiotics, few mo's in blood, etc
  33. Acute bacterial endocarditis
    • a. initial symptosm: fever, chills, weakness (i.e. nonspecific type symptoms)
    • b. rapid onset, later symptoms: decreased cardiac output and microcoaagulation of peripheral blood (rapidly fatal)
    • c. usually caused by S. aureus
    • d. parenteral drug users have a milder form of this disease that is more like SBE
  34. Septicemia (AKA sepsis, bacteremia)
    • 1. bacteria growing in blood stream
    • 2. often septicemia is secondary to other problems: patient is immuno-compromised, pneumonia, TB, burn patient, syphilis, invasive GI bacteria, gangrene, cellulitis
  35. Septiciemia cont
    fever and malaise, then decrease in cardiac output, decrease in bp, decrease in temp, acute systematic inflammation (septic shock) and deat
  36. Septicemia cont
    bacterial products in the blood stream produces what?
    • a toxemia leading to systemic shock
    • 1. lipid A of LPS of Gm- cell membrane are present in Gm- systemia
    • 2. treatment with antibiotics leads to release of more endotoxins, often resulting in systemic shock and death
  37. Septicemia from zoonotic sources
    • a. bites can introduce mo's directly into the blood stream or tissues
    • b. mo's can be pathogens carried by the animal (e.g. rabies, malaria, plague)
    • c. mo's can be part of oral normal flora which can also be very dangerous (e.g. human)
    • d. bites often cause bacterial systemias
  38. Septicemia from zoonotic sources cont.
    • a. Yersinia pestis
    • 1. short, Gm- rod
    • 2. facultative
    • b. Main vir factor: antiphagocytic capsule
    • c. transmission: flea bite or droplet nuclei from pneumonia
  39. Septicemia from zoonotic sources cont.
    Plague cont
    course of disease
    • 1. flea bites infected rodent (usually rat or ground squirrel)
    • 2. bacilli multiply in gut of flea
    • 3. gut becomes blocked
    • 4. flea bites host bug gut is blocked resulting in regurgitated blood back into the bite
    • 5. mo's carried to regional lymph nodes of of new host
    • 6. mo's not phagocytized and multiply in node
    • 7. infected node becomes pus filled, swollen: bubo
    • 8. systemia follows with generalized symptoms plus the buboes
    • 9. systemic shock precedes death (nearly 100% fatal at this stage)
    • 10. takes 3-5 days
  40. Plague cont
    what was the vector called in the US?
    History in Europe
    treatment: prompt antibiotics (before the systemia is too severe)
  41. Vector was from ground squirrel
  42. pneumonic plague and the black death in Europe in the 14th centrury
  43. Septicemia from zoonotic sources

    • a. Franciella tularensis
    • 1. Gm- coccobacillus
    • 2. aerobic, obligate intracellular
    • 3. vir: antiphagocytic capsule
  44. Tularemia cont

    mo's is found in a variety fo rodents, birds and ticks
  45. Tularemia cont

    human disease is of 3 varieties, depending on mode of infection. What are the varieties?
    • a. typhoid-like tularemia from eating undercooked infected rabbits
    • b. pneumonic tularemia: inhaled blood spray or other infectious aerosol (bio-weapon?): like pneumonic plague, high mortality
    • c. ulcerative: cut or infected tick bite (most common) will lead to a local lesion that can spread to a regional lymph node and then a systemia
    • Treatment: prompt, prolonged antibiotics: Russian-made vaccine
  46. Septicemia from zoonotic sources cont

    Lyme disease
    • a. 1st detected in the city of Lyme, Ct. in 1975 and thought to be arthritis
    • b. Borrelia bergdorferi
    • 1. spirochete
    • 2. spiral shape
    • 3. must be grown in animal host
    • Outdoorsy people most likely to get Lyme disiease during spring and summer time
  47. Septicemia from zoonotic sources cont

    Course of Lyme disease (3 stages)
    • 1. target-like rash at site fo tick-bite, which then fades (75% of patients have this)
    • 2. 2-3 weeks after rash starts to fade, a systemia leads to flu like symptoms, irregular heart beat, neurological symptoms: facial paralysis, encephalitis (antibiotics effective up to this point)
    • 3. moths to years later, symptoms caused by hypersensitivity to mo: severe arthritis
    • Treatment: long term antibiotics
  48. Septicemia from zoonotic sources cont.

    Rickettsial diseases
    • Rickettsia spp.
    • 1. very small Gm- rods
    • 2. aerobes
    • 3. obligate intracellular parasites
    • Vectors: blood sucking insects like ticks, body lice, chiggers
  49. Rickettsial disease cont
    2 groups
    Spotted fever group
    • Spotted fever group is represented in the Western Hemisphere by Rocky Mtn spotted fever.
    • 1. Rickettsia rickettsii
    • 2. tick-borne
    • Course of disease
    • a. 2-14 days after tick bite: high fever, chills, headache
    • b. 2-3 days later: petichial rash that spreads from extremities to thorax (not always present), mo lives in endothelial cells.
    • c. late stage includes GI symptoms, encephalitis, renal failure, resp. failure, diffuse intravasc. coagulation and 20-40$ mortality.
    • Avoidance/treatment:avoid being bitten by ticks, treat with antibiotics before late stage symptoms (difficult to Dx without the rash)
  50. Rickettsial disease
    2 groups
    Typhus group
    • Rickettsia prowazekii
    • 1. endemic or louse-borne typhus
    • 2. vector is body louse
    • a. problem of crowded areas of poor personal hygiene, e.g. refugee camps, armies in the field
    • 3. Siege of Granada in 1490, 5-6x due to disease
    • 4. course of disease: abrupt high fever and stupor, headache, 40% of cases report rash, cardiac and CNS dysfunction with high mortality
    • Avoidance/treatment: avoid being bitten by lice (field showers), vaccine is available, treat with antibiotics before late stage symptoms.
    • (isolated cases difficult to Dx w/o the rash)
    • In US, cases are mostly from fleas from flying squirrels
  51. Disease of Circulation cont
    Gas gangrene
    • 1. mo's: Clostridium perfringens and other Clostridial spp.
    • a. Gm+, large sporing rods, anaerobic
    • b. produces a wide variety fo vir and inv factors, esp. hydrolytic enzymes that enlarge the wound and spread the infection
    • c. spores commonly found in soil and GI tract
  52. Gas gangrene

    course of the disease
    • a. deep wound & introduction of feces or soil provides inoculum (e.g. military type wound)
    • b. spores germinate in anaerobic environment
    • c. cells produce copious amounts of hydrolytic enzymes: destroys circulation, tissue death, deepens the wound, spreads the infection.
  53. Gas gangrene

    Symptoms (in 6-72hrs)
    • Swelling
    • inflammation
    • pain, fever
    • foul-smelling gas in wound
    • tissue necrosis
    • then... systemia, with aggressive behavior, delirium and death
  54. Gas gangrene cont

    Treatment (100% fatal if not treated)
    • a. prompt cleaning of wounds
    • b. surgery to remove necrotic tissue (debridement)
    • c. amputation
    • d. hyperbaric chamber (kills Clostridia by forcing O2 into the wound)
    • Note: gangrene is a common consequence of diabetes, as progresive loss of circulation leads to tissue death in the toes, then legs.
  55. Diseases of circulation cont

    other diseases of circulation
    • a. bacterial : anthrax
    • b. viral: small pox, Burkett's Lymphoma and EB virus, mononuecleosis, CMV, hemorrhagic fevers
    • c. protozoal: malaria, Chagas' disease, toxoplasmosis, Leishmaniasis
    • d. helminthic: Schistosomiasis, swimmer's itch
  56. Bacterial diseases of the Upper Respiratory tract.
    Functions of URT
    • eating
    • taste
    • smell
    • hearing
    • air processing and conduction
  57. Protection of URT
    • 1. mucous to entrap mo's
    • 2. sneezing to dislodge
    • 3. macrophages to engulf
    • 4. IgA
    • 5. normal flora
    • 6. inflammation
  58. URT disease

    • 1. Gm+ cocci in chains
    • 2. facultative, but catalase - (acts like an aerotolerant anaerobe)
    • 3. fastidious, nasopharyngeal species isolated on Blood agar
    • 4. many species, classification based on surface Ag's
  59. Streptecoccus
    classification basis
    • 1. proposed by Rebecca Lancefield
    • 2. different strep species were grouped by common surface Ag's
    • 3. used agglutination tests,
    • 4. groups are designated by letters
  60. Streptococcus
    • Group A: Streptococcus pyogenes
    • Group B: Strep agalactiae
    • URT normal flora
    • stubborn nosocomial systemia, pneumonia in comprimised
    • serious systemia, meningitis acquired from mother during birth in neonates
    • historically was a common cause of puerperal fever (childbirth fever) (Oliver Wendel Homes and I. Semmelweis and antisepsis)
  61. Streptococcus classification cont

    Group C & D
    • Group C: Streptococcus angiosus complex
    • Stubborn opportunists
    • Group D?: many spp.
    • URT or GI normal flora
    • Ocasional opportunists
  62. Viridans streptococci
    • Variety of oral, GI and GU normal flora streptococci
    • viridans = green, refers to appearance on blood agar
    • occasional opportunists
    • notables: S. mitis, S. salivarius, S. pnueumoniae
    • lack surface Lancefield Ag's
  63. Isolation of streptococci from oral cavity
    • 1. are fastidious, usually grown on blood agar +/- increased CO2 (differential medium)
    • 2. Hemolysis of blood cells indicate which hemolysins the isolate makes:
    • Group A: β-hemolysin, pathogen
    • Group B: mostly β-hemolysin, likely pathogen
    • Group C: mostly β-hemolysin, likely pathogen
    • most others: α-hemolysin, non-pathogen or opportunist, except for S. pneumoniae
  64. Isolation of streptococci from oral cavity (cont
    Hemolysis of blood cells: a quick screen for pathogens in the URT
    Group A, B and C: β-hemolysin, possible pathogen

    • most other strepts: α- hemolysin, non-pathogen except for S. pneumoniae
    • most other strepts: have α-hemolysin & are non-pathogenic (except for S. pneumoniae which has an obvious capsule)
  65. vir and inv factors (S. pyogenes)
    • 1) β-hemolysin
    • 2) Streptolysin: cytotoxic
    • 3) M Ag (fimbrae): antiphagocytic
    • 4) others
  66. Streptococcal pharyngitis (strep throat)
    • 1) caused by Group A only
    • 2) symptoms (throat epithelium, esp. tonsils) •swollen +patches of pus on tonsils •red •pain •inflammation •fever, malaise
    • 3) transmission: droplet nuclei, fomites
    • 4) treatment: prompt antibiotics
    • if strep throat goes untreated, 2° effects or infections can occur
  67. possible consequences of untreated strep throat
    1. Scarlet fever
    • a) strain has a lysogenic phage that codes for an erythrogenic exotoxin
    • b) rash of chest and extremities, later desquamation
    • c) yellow exudate of tongue, later desquamation
  68. possible consequences of untreated strep throat (cont)
    • 2) otitis media (middle ear infection)
    • 3) Rheumatic fever: cross reacting Ab’s attack mitral valve of heart and joints
    • 4) Glomerulonephritis: inflammation of the kidneys with edema and hypertension
    • c. other possible diseases of S. pyogenes: impetigo, necrotizing fasciitis, cellulitis, pyoderma, erysipelas, systemia, TSS, pneumonia
  69. Diphtheria
    • 1) Corynebacterium diphtheriae
    • a) Gm+ pleomorphic rod
    • b) palisades arrangement
    • c) + metachromatic granules (PHB)
    • 2) course of the disease
    • a) transmission: airborne, droplet nuclei, fomites
    • b) sore throat, fever, malaise
    • c) then diphtheritic membrane forms, a serum clot, which is Dx
    • d) Toxin: phage-borne powerful exotoxin
    • e) toxin leads to heart and kidney failure, trouble swallowing, death
    • 3) treatment: DPT vaccine contains diph. toxoid
    • a) very effective
    • b) diph. well controlled in US
    • 4) a cutaneous form exists, mostly in the homeless