Respiratory Infections Flashcards

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1
Q

Location of Respiratory Infections

A

Trachea, Bronchi, Bronchioles, Alveoli

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2
Q

Barriers to infection

A

Nasal hair, Mucosillary cells, Coughing, Normal flora, Phagocytic inflammatory cells

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3
Q

Normal flora

A
  • changes with time (due to hospitalization)

- alpha hemolytic colonies in pharyngeal culture

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4
Q

Pathogens

A
  • alpha hemolytic colonies in sputum or bronchial aspirate
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5
Q

Differentiating infection

A
  • look at method and site of infection
  • presence of white blood cells
  • number of organisms present
  • clinical syndrome present
  • some pathogens are always present (M.TB)
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6
Q

Respiratory Infections (Risk Factors)

A
  • Imunnologic status
  • Age (elderly, young at higher risk)
  • Reduced clearance promotes infection
  • Airway obstruction (H. flu epiglottitis)
  • Seasonal patterns contribute (M. pneumo has none)
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7
Q

Empirical treatment

A
  • antibiotics should be given before ID for ICPs
  • infections with hard-to-reach specimens
  • infections with known/recurring pathogens
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8
Q

Virulence factors

A
  • adherence, fimbrae (Enterics, Streps)

- toxin elaboration (C. diphtheriae, Pseudomonas, pertussis)

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9
Q

Evasion of host defense

A
  • capsules for preventing phagocytosis (S. pneumo, H. flu, Pseudomonas, Klebsiella)
  • intracellular (TB, Chlamydia)
  • Proteases (cleave antibodies)
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10
Q

Upper Respiratory Tract Infections

A

Pharyngitis, Sinusitis, Otitis media, Epiglottitis, Pertussis

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11
Q

Pharyngitis

A
  • commonly Group A strep in kids or viral (with rhinorrhea)
  • symptoms of Group A strep
  • culture or rapid antigen testing
  • person-to-person transmission
  • pain, difficulty swallowing, fever with bacterial
  • C. diphtheriae: pharyngeal membrane
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12
Q

URT Infections (pathogenesis)

A

inflammatory effects of bacteria

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13
Q

URT complications

A

sinusitis, otitis media, pneumonia

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14
Q

URT lab diagnosis

A
  • primary: differentiate between viral and bacterial

- secondary: detect uncommon bacterial causes

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15
Q

URT culture

A
  • streak SBA
  • Latex agglutination
  • Rapid antigen test
  • treat with penicillins and cephalosporins
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16
Q

Sinusitis (causes)

A
  • commonly viruses (rhinovirus, influenza)
  • 2% are bacteria (S. pneumo, H. flu, S. pyogenes, M. catarrhalis, S. aureus)
  • fungal is uncommon
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17
Q

Sinusitis (pathogenesis)

A
  • swelling and blockage of sinuses
  • pain and possible complications
  • complications: orbital cellulitis, osteomyelitis, meningitis
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18
Q

Sinusitits (lab diagnosis)

A
  • direct sinus puncture or aspiration
  • culture on SBA, MAC, Chocolate
  • empirical information
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19
Q

Otitis media

A
  • most common in preschool aged kids

- fever, irritability, ear pain, drainage, red tympanic membrane

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20
Q

Otitis media (pathogenesis)

A
  • due to anatomic immaturity

- causes damage to tympanic membrane

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21
Q

Otitis media (lab diagnosis)

A
  • empirical

- antibiotic treatment in kids < 2 y/o

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22
Q

Epiglottitis

A
  • caused by Hib

- preschool-aged kids

23
Q

Epiglottitis (pathogenesis)

A
  • severe pharyngitis, sore throat, severe pain on swallowing
  • edema in soft tissues
  • sudden onset of airway obstruction
  • requires hospitalization and IV fluids
24
Q

Epiglottits (lab diagnosis)

A
  • direct swab culture and blood cultures
  • direct smear (WBC’s, pleomorphic GNR’s = H. flu)
  • culture on chocolate
25
Q

Pertussis

A
  • caused by Bordetella
  • highly transmissible in ICPs, babies
  • vaccine available
26
Q

Pertussis (pathogenesis)

A

pertussis toxin

27
Q

Pertussis (lab diagnosis)

A
  • nasopharyngeal swab using Dacron/Calcium alginate
  • plate on Bordet-Gengou
  • serology: DFA testing, PCR testing
28
Q

Lower Respiratory Tract Infections

A
  • Bronchitis, Bronchiolitis, Influenza, SARS, Pneumonia, Empyema, TB
  • caused by inhalation of aerosols, aspiration of oral/gastric contents, or hematogenous spread
29
Q

Bronchitis and Bronchiolitis

A
  • follows epidemics of influenza, RSV, and other viruses

- more frequent in winter months

30
Q

Bronchitis and Bronchiolitis (pathogenesis)

A
  • infection and damage to the airway
  • inflammatory response, necrotic debris, edema
  • begins as URT infection
  • acute is infectious form
  • chronic requires 3 months of symptoms for 2 years
31
Q

Bronchitis and Bronchiolitis (lab diagnosis)

A
  • similar procedure as pharyngitis
  • secondary infection easily obtained from sputum
  • hospitalized patients tested for RSV for infection control
32
Q

Influenza

A
  • late fall, early winter

- Influenza A and B

33
Q

Influenza (pathogenesis)

A
  • antigenic shift (production of new virus)

- fever, myalgia, fatigue

34
Q

Influenza (diagnosis)

A
  • detection of virus, viral antigen, or viral nucleic acid

- treat with neuraminidase inhibitors or vaccine

35
Q

Severe Acute Respiratory Syndrome (SARS)

A
  • fever without cough
  • dyspnea
  • progressive respiratory failure
36
Q

LRT (Viral causes)

A

Adenovirus, Metapneumovirus, Bocavirus

37
Q

Community-acquired pneumonia

A
  • most affected are elderly or have underlying disease
  • kids/elderly: RSV, parainfluenza
  • adults: S. pneumo, Hib, M. pneumo
  • atypical: M. pneumo, Legionella pneumophila
38
Q

C-A pneumonia (pathogenesis)

A
  • fever, lung infiltrates

- cough with blood-tinged sputum, left shift WBC count

39
Q

C-A pneumonia (lab diagnosis)

A
  • therapy is empirical
  • blood cultures and sputum on hospitalized patients
  • PCR and other molecular tests
  • antigen tests
  • direct examination of sputum
40
Q

Direct examination of sputum

A

Acceptable: < 10 epithelial cells, > 25 PMN’s

41
Q

Expectorated sputum

A
  • no WBCs
  • heavy epithelial and bacteria
  • saliva, not sputum
42
Q

Aspirated sputum

A
  • no WBCs or organisms

- specialized cells from bronchial tree and mucus

43
Q

Health Care-Associated Pneumonia (HCAP)

A
  • hospitalized or in a nursing home facility
  • can also be ventilator associated pneumonia (VAP)
  • greater risk of multi-drug resistant pathogens
  • Pseudomonas, Kleb. pneumo, Acinetobacter, MRSA
44
Q

HCAP (pathogenesis)

A
  • patients own respiratory flora, GI tract or hospital flora
  • due to aspiration of flora
  • intubation of lower airway pushes flora deeper
  • nasogastric intubation
  • fever, altered WBC count, purulent sputum
45
Q

HCAP (lab diagnosis)

A
  • same as community-associated
  • expectorated sputum specimen
  • SBA, Chocolate and MAC
  • anaerobic cultures if no contamination
46
Q

Empyema

A
  • collection of purulent fluid in pleural cavity

- S. aureus, S. pneumo, S. pyogenes

47
Q

Empyema (pathogenesis)

A
  • fever, chills, night sweats
  • complicates chest surgery
  • limits motion and function of lungs
  • resistant to antimicrobials
48
Q

Empyema (lab diagnosis)

A

aspirate of pleural fluid (thoracentesis)

49
Q

Tuberculosis

A
  • Mycobacteria in ICP’s
  • NTM’s (Mac, M. kansasii, M. chelonae)
  • Opportunistic fungal pathogens
50
Q

Tuberculosis (lab diagnosis)

A
  • acid-fast stain
  • skin test
  • serology, nucleic acid tests
51
Q

Aspiration pneumonia

A
  • gastric or oropharyngeal are inhaled into LRT
  • C-A: S. pneumo, H. flu, Staph, Enterics
  • HACP: Gram-negatives like Pseudomonas
  • use broad spectrum antibiotics
52
Q

Respiratory Infections in ICPs

A
  • Pneumocystis
  • Bacterial pneumonia and tuberculosis
  • Cryptococcus
  • Lab: sputum and blood culture, acid-fast, fungal tests
53
Q

Bioterrorism respiratory infections

A

B. anthracis (anthrax attack in 2001)