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Flashcards in Micro: Respiratory Deck (37)
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1
Q
  • Gram + bacteria
  • Cocci
  • Catalase +
  • Coagulase +
  • Protein A: binds to Fc portion of hoist IgG
  • Local: skin/subcutaneous: impetigo cellulitis, folliculitis, furuncles, carbuncles, respiratory, pneumonia w/ cavitations
  • Systemic: Acute Endocarditis, Menigitis, Osteomyelitis (children), Septic arthritis
  • Protein A – binds Fc portion of IgG
  • Coagulase (forms fibrin coat around organism)
  • Hemolysins, Leukocidins – destroy RBCs and WBCs
  • Neutrophils localize to infection site -> purulent abscesses form -> skin/subcutaneous infections or pneumonia
  • Bacterial invasion of bloodstream
    • Hyaluronidase – breaks down connective tissue
    • Staphylokinase – lyses formed clots
    • Lipase – breaks down fat
  • Hematogenous spread to visceral organs -> systemic infection
  • Dx: blood culture +, Gram + clusters, Catalase +, Coagulase +
  • Tx: MSSA (methicillin-sensitive S. aureus) -> Penicillinase-resistand penicillins,
    MRSA (methicillin-resistant S. aureus) -> vancomycin
A

Staphylococcus aureus

2
Q
  • Gram +
  • Catalase –
  • Bile-esculin negative
  • Optochin susceptable
  • Diplococci
  • Quellung rxn +
  • Local: Lobar pneumonia, Otitis media, Sinusitis
  • Systemic: Meningitis, Septic arthritis, Endocarditis
  • Evades host defenses by: Capsule (escapes phagocytosis), IgA proteases
  • Alveoli inflammation: disseminate via pores fo Kohn -> Lobar pneumonia
  • Tx: Penicillin, Cephalosporins (except Vanco for meningitis)
  • Asplenic patients are especially susceptible, unable to remove Ab-coated organisms (give Pneumovax)
A

Streptococcus pneumoniae

3
Q

Common Causes of Pneumonia in?

  • Adults (40 – 65 yrs)?
  • Elderly (> 65 yrs)?
  • Most common cause of meningitis in 60+ yrs?
A
  • Adults (40 – 65 yrs)
    • S. pneumoniae
    • H. influenzae
    • Legionella
  • Elderly (> 65 yrs)
    • S. pneumoniae
    • Gram – rods
    • H. influenzae
  • Most common cause of meningitis in 60+ yrs
    • S. pneumoniae
    • Gram – rods
    • Listeria
4
Q
  • Acid-fast bacteria w/ Mycolic acid cell wall
  • Thin rods, non-motile, Obligate Aerobic
  • Grows at body temperature
  • Caseous granulomas
  • Ghon complex on CXR (calcified pulmonary tubercles + Hilar lymph nodes)
  • IFN-γ released by Lumphocytes exposed
  • Primary – Lower Lobes of Lungs
  • Secondary – Upper Lobes – High O2 and Low Lymphatics
  • (Miliary) disseminate to other sites thru Lymphatics
  • Tx: RIPES
A

Mycobacterium tuberculosis

5
Q

Clinically important bacteria that have acid-fast positive staining?

A
  • Mycobacteria
    • Mycobacterium tuberculosis
    • Mycobacterium avium
    • Mycobacterium intracellulare
  • Nocardia
6
Q
  • Fungi
  • Systemic infection, immunocompromised, pneumonia
  • Asymptomatic, immunocompetent
  • Granulomas may form throughout the body
  • Dx: Serology, Branched Hypae at 25°C, Single cells at 37°C
    • Intradermal inj. Of Coccidlidin antigen causes DTH response
  • Tx: Supportive, anti-fungals (systemic), Amphotericin B (CNS not involved) and Fluconazole (if CNS is involved)
A

Coccidioides immitis

7
Q

Systemic mycoses are endemic to particular areas?

  • Southwest U.S. -> ?
  • Mississippi/Ohio River Valleys, Southeast U.S. river basins -> ?
  • East of Mississippi River and Central America -> ?
A
  • Southwest U.S. -> Coccidioido mycosis
  • Mississippi/Ohio River Valleys, Southeast U.S. river basins -> Histoplasmosis
  • East of Mississippi River and Central America -> Blastomycosis
8
Q
  • Fungi
  • Systemic infection, pneumonia
  • At 37°C the spores become yeast -> local Lung infection -> Acute pneumonia and Granulomas throughout the body
  • Dx: Serology, Branched Hypae at 25°C, Single cells at 37°C
  • Biopsy: Large budding yeast
A

Blastomyces dermatitidis

9
Q
  • Fungi
  • Systemic infection, immunocompromised
  • Asymptomatic, immunocompetent
  • Bird droppings are inhaled -> Macrophages phagocytose spores -> budding yeast from w/in -> infection w/in epithelioid granulomas -> small Ca2+ deposits on CXR (esp. Adrenals, Liver, Spleen)
  • Dx: Serology, Branched Hypae at 25°C, Single cells at 37°C
  • Yeast cells w/in Histocytes (Macrophages)
  • Histoplasmosis a sign of AIDS in HIV-positive exp. to Bird shit.
  • Intradermal injection of Histoplasmin antigen -> DTH response
  • Tx: Supportive, Antifungals (systemic), Amphotericin B, Ketoconazole, Itraconazole
A

Histoplasma capsulatum

10
Q
  • No cell wall
  • Marked Pleomorphism
  • Resistant to b-lactam ABX
  • No Gram stain
  • Cultures have ‘fried-egg’ appearance
  • Tracheobronchitis (via P1 adhesion) – Atypical pneumonia “walking pneumonia” – Vacuolation and Ciliostasis (inhibits ciliary motion)
  • Young people – in Close Quarters (Prisons, Military, Colleges)
  • Produces CARDS toxin – homolog to Pertussis toxin
  • Dx: Cold Hemagglutination -> > 4x IgM Ab bind RBCs after 1-2 weeks w. Eaton’s agar
  • CXR looks worse then symptoms suggest
  • Tx: Tetracycline or Macrolides (Erythormycin or Azithromycin), b-lactam ABX are NOT effective
A

Mycoplasma pneumonia

11
Q

Common causes of atypical pneumonia?

A
  • Mycoplasma
  • Legionella
  • Chlamydia
  • Viruses
12
Q
Most common causes of pneumonia
in adults (18 – 40 yrs)?
A
  • Mycoplasma
  • C. pneumoniae
  • S. pneumoniae
13
Q
  • Atypical pneumonia
  • Community acquired, Young adults
  • Phagocytosed by macrophages -> lymphocye infiltration at site of infection -> local pulmonary edema, necrosis, and hemorrhage
  • (2) Forms in the Life cycle
  1. Extracellular elementary body (EB) -> infective form
  2. Intracellular Reticular body (RB)
  • EB upper respiratory -> EB phagocytosed -> EB transforms into RB -> special cell wall blocks phagosome lysosome fusion -> RB multiplies w/in intracellular body -> RB condenses to EB -> EB bursts
  • Dx: Giemsa stain to visualize intracytoplasmic inclusions
  • Tx: intracellular ABX: Doxycycline
A

Chlamydia pneumoniae (TWAR)

14
Q

Two obligate intracellular parasites
(require host ATP for energy)?

A
  • Chlamydiae -> replicate w/in inclusion bodies
  • Rickettsiae -> replicate freely w/in cytoplasm
15
Q
  • Most frequent cause of bacterial STD in U.S.
  • Most common cause of Blindness worldwide
  • Serovars A-C: trachoma (chronic conjunctivitis)(hand-eye contact)
  • Serovars D-K: Urethritis, PID, Neonatal pneumonia, Neonatal conjunctivitis, Cervicitis, Inclusion conjunctivitis (columnar epithelium)
  • Serovars L1-L3: Lymphogranuloma venereum (LGV), STDs
  • Complications: Fitz-Hugh-Curtis syndrome, Reiter’s syndrome (HLA-B27)
  • Dx: PCR, Transcription-mediated amplification, Iodine stain +, Giemsa stain +
  • Tx: Azithromycin, Tetracyclines (+ceftriaxone for concurrent N. gonorrhea), Oral Erythromycin for Neonates w/ infected mothers, Prophylactic Erythromycin eye drops for Neonates
A

Chlamydia trachomatis

16
Q

Common causes of non-gonoccal
urethritis (NGU)?

A
  • Chlamydia trachomatis
  • Ureaplasma urealyticum
17
Q
  • Atypical pneumonia
  • Endocarditis
  • Carried by birds (parrots) -> bird feces -> Upper respiratory tract
  • Phagocytosed by macrophages -> lymphocye infiltration at site of infection -> local pulmonary edema, necrosis, and hemorrhage
  • (2) Forms in the Life cycle
  1. Extracellular elementary body (EB) -> infective form
  2. Intracellular Reticular body (RB)
  • EB upper respiratory -> EB phagocytosed -> EB transforms into RB -> special cell wall blocks phagosome lysosome fusion -> RB multiplies w/in intracellular body -> RB condenses to EB -> EB bursts
  • Dx: Visualize intracytoplasmic inclusions, Iodine stain -, Giemsa stain +, > 4x rise in Ab titer, Single IgM > 1:16, Microimmunofluorescence
  • Tx: ABX that enter cell: Doxycycline, Macrolides(Erythromycin or Azithromycin)
A

Chlamydia psittaci

18
Q
  • Atypical pneumonia
  • Does NOT cause Rash
  • Endospore w/in cell
  • Carried in Cattle, Sheep, Goats
  • Survives extracellularly as a spore -> inhalation -> atyp. pneu. -> leads to Hepatitis, Chronic Endocarditis
  • Dx: Serology, Culture w/in cells, Weil-Felix –
  • Tx: Tetracycline
A

Coxiella burnetii (a Rickettsia)(Q Fever)

19
Q
  • RNA virus
  • Helical nucleocapsid
  • Enveloped
  • SS- nonsegmented
  • Paramyxoviridae
  • HA/NA (binds sialic acid/cleaves, sialic acid interaction
  • F (causes infected cells to fuse)
  • M protein (involved in assembly)
  • Children (croup – Laryngotraccheobronchitis, pneumonia)
  • Adults (common cold)
  • Hemagglutinin (HA) envelope protein binds sialic acid on cells
  • Neuroaminidase (NA) envelope protein cleaves HA – sialic acid interaction to permit viral spread down Tracheal and Bronchial epithelium
  • Obstruction of insipiration (insipiratory stridor) and expiration (barking cough) -> Croup
  • Dx: Hemagglutination act. in resp. secretions, anti-HA ABX inhibit
  • Tx: Supportive (cool mist, oxygen in severe cases), Corticosteroids
A

Parainfluenza Viruses (Paramyxoviridae Paramyxovirus, Paramyxoviridae Rubulavirus)

20
Q

Most common causes of pneumonia
in Young Children?

A
  • RSV
  • Parainfluenza virus
21
Q
  • RNA virus – respiratory syncytial virus
  • Helical nucleocapsid
  • Enveloped
  • SS- nonsegmented
  • Paramyxoviridae
  • G (allows virus to attach to cells)
  • F (causes infected cells to fuse)
  • Children (bronchiolitis -> Asthma + wheezing, pneumonia)
  • Adults (common cold)
  • Nasal secretions -> hand2hand and aerosol -> attaches to Bronchiolar and Alveoli epithelium via G protein on viral envelope
  • Dx: Det. w/in resp. secretions, serology
  • Tx: Supportive, Albuterol, Aerosolized Ribvirin (severe), Synagis (Fantigen vaccine) prevent infection in High-risk pts. (Premies, Lung disease, Heard disease)
A

Paramyxoviridae Pneumovirus –
Respiratory Syncytial Virus (RSV)

22
Q
  • DNA viruses
  • Icosahedra nucleocapsid
  • Non-enveloped
  • DS linear
  • Adenoviridae
  • HA fiber protruding from each of 12 vertices of capsid
  • Respiratory tract infection, Conjunctivitis, Hemorrhagic cystitis, Gastroenteritis
  • Fecal-oral route -> bind via hemagglutinin -> enters and lyses mucosal cells
    • Upper respiratory tract -> rhinitis, sore throat -> lower atyp. pneu.
    • Conjunctiva -> Conjunctivitis
    • Bladder -> Hemorrhagic cystitis -> Hematuria, Dysuria
    • GI tract in kids -> Gastroenteriris w/ non-bloody Diarrhea
  • Dx: Serology, Isolation of virus in cell culture
  • Tx: Vaccine w/ live viruses (only military)
A

Adenoviridae Mastadenovirus

23
Q

Causes of common cold?

A
  • Rhinovirus
  • Coronavirus
  • Adenovirus
  • Influenza C virus
  • Coxsackivirus
24
Q

Most common causes of conjunctivitis?

A
  • H. influenza
  • Adenovirus
  • S. pneumoniae
25
Q
  • DNA viruses
  • Icosahedral nucleocapsid
  • Enveloped
  • DS linear
  • Herpesviridae
  • Intranuclear inclusion bodies form in infected cells because virus replicates w/in nucleus
  • Envelope (only virus that obtains envelope by budding from nuclear membrane)
  • Infectious mononucleosis (“kissing disease”)
  • Lymphoid orgain-related cancers: Burkitts’s Lymphoma (neoplasms), nasopharyngeal cancer (in East Asians)
  • Infects B cells via C3d complement receptor -> latent in B cells as episomal DNA -> Lymph nodes, Spleen enlarge w/ flu like symptoms
  • Dx: monospot test – detects heterophil Ab (agglutinates sheep RBCs), Blood smear – w/ cytotoxic T lymphocytes that react against B cells, anti-EBV IgM (acute infection) and IgG (past infection)
  • Tx: Acyclovir (severe cases)
A

Herpesviridae Lymphocryptovirus

(EBV or Herpesvirus 4)

26
Q
  • Gram – bacteria
  • Coccobacilli, pleomorphic
  • Growth of Bordet-Gengou medium
  • Filamentous hemagglutinin (FHA)
  • ‘Safety-pin shape’
  • Children -> “Whooping cough”
  • Adults -> cold w/ nagging cough
  • Adheres to cilia of resp. epith. Via FHA -> release exotoxins
  • Pertussis toxin -> AB toxin -> ADP-ribosylates and inactivates GI proteins -> uninhibited adenylate cyclase -> increase cAMP -> Lymphocytosis, decreased phagocytosis
  • Cytotoxin -> kills ciliated epi. Cells -> impairs muccous clearance
  • (3) Stages
  1. Catarrhal stage (1 – 2 weeks) - flulike symptoms, highly contagious
  2. Paroxysmal stage (3rd week – 2 months) intermittent bouts of many coughs on a single expiration followed by whooping inspiration
  3. Recovery stage (2 -3 months) – coughing subsides
  • Dx: Gram - , Coccobacilli, Bordet-Gengou medium
  • Tx: Prophylaxis: DtaP vaccine: acellular Pertussis antigens, treatment: erythromycin (only before paroxysmal phase), supportive care
  • DTaP: 2, 4, 6, and 18 months and every 10 years
A

Bordetella pertussis

27
Q
  • Gram – bacteria
  • Bacilli
  • Lactose non-fermenter
  • Oxidase +
  • Glucose non-fermenter
  • Pneumonia (CF patients); UTIs, Burn wounds, Septicemia, Endocarditis (IV drug users), Oseomyeitis (DM, IV drug users), Malignant ext. otitis (DM), Folliculitis (Hot tubs)
  • Exotoxin A -> ADP ribosylates host EF2 -> paralyzes host protein machinary
  • Phospholipase C -> Cleaves phosphates from phospholipids
  • Elastase -> cleaves elastin -> allows microorganism to disseminate to better nutrient sources
  • Endotoxin -> shock
  • Dx: Gram – rods, Blue-green colonies (pyocyanin pigment) w/ Fruity odor
  • Tx: anti-Pseudomonal penicillin + aminoglycoside (piperacillin + gentamicin, mezlocillin + gentamicin), Gluoroquinolones, and other ABX combinations
A

Pseudomonas aeruginosa

28
Q
  • Gram – bacteria
  • Coccobacilli, pleomorphic
  • Growth on charcoal yeast agar w/ Iron (Fe) and Cysteine (Cys)
  • Pontiac fever -> acute flulike illnes lasting 2-5 days
  • Legionnaire’s disease (atypical pneumonia) -> neutrophils arrive and form microabscesses
  • Naturally inhabits water reservoirs -> inhaled aerosois from respiratory devices -> survives and proliferates inside nutrient-rich phagosome -> weakens macrophage resp. burst -> prevents phagosome from fusing w/ lysosome
  • Dx: Gram stains poorly, Use Silver stain, culture on charcoal yeast extract w/ Fe and Cysteine, Urinary antigen detected by Radioimmunoassay serology
  • Tx: Erythromycin
A

Legionella pneumophila

29
Q
A
30
Q
A
31
Q
A
32
Q
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33
Q
A
34
Q
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35
Q
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36
Q
A
37
Q
A