Med Micro Exam 2

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jmturner
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178008
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Med Micro Exam 2
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2012-10-18 15:24:57
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Med Micro Exam
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Infections and pathogens
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  1. Four most common causes of bacterial meningitis

    they all have capsules and IgA1 protease; treated with penicillin
    • Haemophilus influenzae
    • Neisseria meningitides
    • Listeria monocytogenes
    • Streptococcus pneumonia
  2. Streptococcus pneumonia
    • most common community-acquired
    • G+ cocci
  3. Haemophilus influenzae
    • is rare due to the HIB vaccine
    • G- rod
  4. Neisseria meningitides
    • G- diplococcic
    • facultative anaerobe
    • ferments glucose and maltose
    • VF = capsule (9 serotypes); IgA1 protease; pili (for adherence); endotoxin
  5. Listeria monocytogenes
    • grows at 4 degrees C - in refrigerators
    • G+ coccobacilli
    • facultative anaerobe
    • beta-hemolytic
    • VF = facultative intracellular parasite; flagella; hemolysin; endotoxin (the only G+ bacteria with LPS/lipid A)
  6. Viral Meningitis
    • are the most common CNS infections and are the least severe
    • Normally self-limiting
  7. The most common cause of encephalitis
    • VIRAL
    • some are arthopod-borne aka arboviruses
    • others spread from other organs in body
  8. Most common causes of viral encephalitis
    • MOST COMMON - herpes simplex
    • mumps, varicella-zoster, cytomegalovirus, rabies, Louing III, and HIV
    • Piconaviridae
    • Rhabdoviridae
    • Flaviviridae
    • Prions
  9. Piconaviridae
    • + SS RNA, non-enveloped
    • icoshedral symmetry 
    • 7500+ nucleotides, smallest significant virus
  10. Rhabdoviridae
    • - SS RNA virus, enveloped
    • helical symmetry, bullet-shaped capsid
    • transmission: by the bite of an infected mammal; reservoir: bats
  11. Flaviviridae

    West Nile Virus
    • + SS RNA virus, enveloped
    • transmission: primarily thru mosquito vector; reservior: birds
  12. Prions

    Mad Cow Virus
    • infectious protein
    • filterable
    • resistant to heat, disinfectants. and irradiation (susceptible to phenol)
    • no immune/ inflammatory response
    • can't be cultured in vitro
    • transmission: ingestion, medical procedures, mutation
  13. Cryptococcus neoformans
    • causes meningo-encephalitis
    • encapsulated 
    • replicates thru budding and sporulation
    • found in soil and pigeon droppings; inhaled
    • OPPORTUNISTIC
  14. Toxoplasma gondii
    • sporozoan
    • obligate intracelluar parsite
    • has an asexual/sexual life cycle with cats as host, and humans as intermediates
    • inhaled, ingested, vertical transmission
  15. Upper Respiratory Tract (URT)
    • Nose, Sinus, Throat & Respiratory Airways (trachea, bronchii, bronchioles)
    • Normal flora present & constantly breathing in potential pathogens
    • cellular defense mechanism(immunity)-cytokines
    • mucocilliary ladder(which has cilia lining the tubes to beat and move so anything you breathe in gets forced back up)
    • function: keep the LRT clean & sterile
  16. Lower Respiratory Tract (LRT)
    • bronchioles intercept with lungs -> alveolar ducts -> alveolar sacs -> alveoli
    • Normally sterile; specimen indirect
    • macrophages, complement, B & T cells, lymphoid tissue
    • variety of alveolar lining fluids(surfactants, phospholipids, immunoglobulins, factors – which are cytokines involved w/ bringing in the macrophages)
  17. How do pathogens get in?
    • Inhalation of droplets
    • aspiration
    • hematogenous spread
    • Direct extension
    • Direct contact
  18. Primary vs Secondary Invaders
    • Primary invaders can infect a healthy individual directly 
    • Secondary invaders comes after by taking advantage of VFs of the primary invader and decreased immune system function
  19. Mucin
    • is moved out of the tracheobronchial tree 
    • contains IgA, defensins, and lysozymes
  20. Common Respiratory Tract Infections
    Most are self-limiting

    • common cold (viral)
    • Pharyngitis/tonsilitis (mostly viral)
    • Parotitis (viral)
    • Oral Thrush (fungal - candida albicans)
    • Dental caries (strep. mutans/part of NF)
    • Diphtheria (bacterial - corynebacterium diptheriae)
    • Whooping Cough (bacterial - bordetella pertusis)
    • Bronchitis - (viral followed by bacterial infection)
  21. What is pneumonia?
    It is an infection of the lungs with symptoms that include chest pains, cough (sometimes productive), rigor, and shortness of breath
  22. 1. Community Acquired Pneumonia are... 
    2. and can be further subdivided into...
    • 1. acute: 
    • symptoms develop over 24-48 hours
    • mostly bacterial (1-3 days) and viral (3 weeks) pneumonias

    • 2. Typical:
    • rapid onset
    • severe symptoms
    • productive cough
    • dense consolidation on CXR

    • Atypical: also called "walking" pneumonia
    • slower onset
    • less severe symptoms
    • non-productive cough
    • patchy interstitial pattern on CXR
  23. Diagnosis of pneumonia
    includes the symptoms, patient history, and physical exam (high respiratory rate, systolic pressure, increased pulse, and pulmonary evaluation)
  24. VF of the pathogens
    • facultative intracellular parasite
    • capsule
    • mimicry
    • size
    • toxins
    • hemolysis
  25. Some complications of pneumonia include...
    • secondary pulmonary infections
    • pleural effusion
    • circulartory problems
    • liver/kidney problems
    • abnormal pulmonary function (bronchiectasis)
  26. What are the 5 different classical patterns of laboratory findings for pneumonia?
    • Lobar pattern
    • Bronchopneumonia pattern
    • Interstitial pattern
    • Lung Abscess
    • Nodular Lesions
  27. Streptococcus Pneumonia
    • most common cause of community acquired  pneumonia (typical)
    • G+ diplococcic (lancet shaped)
    • optochin test
    • patial hemolysis (alpha)
    • also causes meningitis, sepsis and otitis media in children
  28. Haemophilus influenzae
    • community aquired pneumonia (typical)
    • G- rod
    • VF= capsule, pili, IgA1 protease
    • green sputum
    • Rigor is rare
    • also caues meningitis, acute epiglotitis, otitis media and sinusitis
  29. Legionella pneumophila
    • community acquired, typical
    • G- rod
    • common in most enviroments
    • VF = capsule, flagella, facultative intracellular parasite, hemolysins, cytotoxin
    • causes confusion and headache
    • minimal sputum
    • special culture media
    • elderly and IC patients
  30. Mycoplasma pneumoniae
    • community acquire atypical pneumonia
    • very small mycobacterium
    • pleiomorphic, no cell wall
    • treatment is empirical
    • common in ppl under 40
    • fever last 1-2 weeks, cough lasts 3-4 weeks
  31. Chlamydia pmeumoniae
    • community aquired, atypical
    • obligate intracellular parasite
    • 5-15% of atypical cases
  32. Chlamydophila psitacci
    • community acquired, atypical
    • G- rod
    • opportunistic infection in AIDS patients
  33. Viral pathogens that causes community acquired atypical pneumomia..
    • influenza A and B
    • adenovirus
    • parainfluenza
    • RSV

    these can lead to bacterial pneumonia
  34. Staphylococcus aureus
    • hospital acquired
    • G+ cocci, clustered/tetrads
    • golden colonies
    • complete hemolysis
    • acute symptoms
    • Risk factors = flu, immunecompromised
    • involved in many other diseases
    • VF= protein A, toxins, enzymes, antibiotic resistance
  35. Klebsiella pnemoniae
    • very damaging
    • (community aquired typical and hospital acquired)
    • G- rod, non motile
    • facultative anerobe
    • VF= capsule, antibiotic resistance
    • red sputum
    • also causes UTI
  36. These pathogens also cause hospital acquired pneumonia
    • CMV
    • P. carinii
    • mycobacterium spp
    • aspergillus
    • nocardia
    • serratia marcescens
  37. Pseudomonas aeruginosa
    • most common cause of hospital acquired pneumonia
    • G- rod, obligate aerobe
    • opportunistic, part of NF
    • VF= antibiotic resistance, flagella, capsule enzmes, toxins
    • green sputum
  38. Blastomyces dermitidis
    • dimorphic fungi
    • lung lesions dont calcify
    • Habitat: Great Lakes, soil and wood
  39. Histoplasma capsulatum
    • dimorphic fungi
    • lung lesions calcify
    • Habitat: MS Valley, bird droppings
  40. Coccidoides immitis
    • dimorphic fungi
    • no lung lesions
    • Habitat: Desert SW. dust
  41. Mycobacterium tuberculosis
    • chronic pneumonia
    • acid fast rod, aerobe
    • VF: cord factor, sulfatides, siderophore, facultative intracellular parasite
    • Diagnosis: PPD (skin test), acid fast stain, DNA probes, CXR
  42. Actinomyces spp. and Nocardia asteroides
    • aspiration
    • G+ rods, branches and beads
    • NF of mouth and GI tract
  43. Other apiration-related pathogens
    • Bacteroides spp: G-
    • Fusobacterium sp.: G-
    • Peptostreptococcus: G+
    • typical acute pneumonia pathogens
  44. Opportunistic pathogens (typically fungal)
    • Candida albicans: hospital acquired, dimorphic fungi,  NF
    • can cause oral thrush, yeast infections, diaper rash

    • Aspergillus spp.: fungus, hospital acquired
    • branching separate hyphae
    • ubiquitous in enviroment
    • aflatoxin (peanut allergies)
    • can also cause aspergillomas and liver damage
  45. Hematogenous Hospital Acquired Pathogens
    • staphyloccocus G+ cocci
    • streptococcus G+ cocci
  46. conjunctivitis
    • a common infection of the membrane on the inside of the eyelids
    • infection due to bacteria, viruses, fungi, and parasites
    • results in dilation of blood vessels, pus formation, swelling, itching, and pain
  47. Chlamydia trachomatis
    • cause conjunctivitis
    • most common cause of blindness in the world
    • G- cocci, obligate intracellular parasite, requires host ATP
    • VF: lysozyme resistance, prevents phagosome-lysosome fusion
    • has 14 serotypes (antigenic variation) 
    • also causes infant pneumonia and NGU
  48. Onchocera volvulus ("river blindness") and Wolbachia pipientis (causes inflammation)
    • cause conjunctivitis
    • blood/tissue nematode
    • reservoir: humans
    • vector: black fly
    • region: africa, central and south america
    • also causes allergic rash and scaly skin
  49. Most common cause of conjunctivitis
    • viral is most common
    • typically bilateral
    • serous exudate

    • fungal: very rare
    • bacterial: comtagious, thick, copious exudate
    • parasitic: typically within developing contries
  50. Keratitis
    • a less common but vision threatening infection of the cornea
    • a foreign object including contact lenses can help microbes (bacterial, viral, fungal, protozoal) gain entry causing pain, inflammation, photophobia, and vision impairment
  51. Acanthamoeba
    • causes keratitis
    • rhizopod protozoan
    • pseudopodia
    • live in water and moist soil
    • also causes meningoencephalits
  52. Otitis Externa
    • "swimmer's ear"
    • ear infections localized within the outer ear
    • typically caused by G- rods
    • can be life-threatening in diabetes and IC patients
    • results in swelling, redness, and pain of the external canal due to trapped water
  53. Otitis Media
    • ear infections localized within the middles sectors
    • common in childrem 
    • results in ear pain, drainage, vertigo, and occasionally hearing loss and potentially fatal mastoiditis
    • often follows a URT viral infection and includes opportunistic NF
  54. Sinusitis
    • caused by bacteria and viruses
    • leads to inflammation, obstruction of the air space openings and increased pressure (sinus pain/headache)
    • often include purulent discharge

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