Infections of the Lower Respiratory System Flashcards

1
Q

clinical classifications of lower respiratory tract infections

A

*pneumonitis
*pneumonia
*community acquired pneumonia
*consolidative pneumonia
*healthcare associated pneumonia
*typical pneumonia
*atypical pneumonia
*tracheitis
*bronchitis
*bronchiolitis
*alveolitis
*bronchopneumonia
*pulmonary abscess
*pleurits
*empyema

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2
Q

pneumonitis - general overview

A

*inflammation of the lung resulting in acute/subacute/chronic disease
*many causes of pneumonitis are not infectious (i.e. hypersensitivity, autoimmune, vasculitis, chemical, etc)

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3
Q

pneumonia - general overview

A

*pneumonitis due to viral, bacterial, or parasitic causes

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4
Q

community acquired pneumonia - general overview

A

*pneumonia arising in an individual in the community (not in a healthcare or long-term care setting)

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5
Q

consolidative pneumonia - general overview

A

*seen on CXR as dense alveolar infiltrate with lobar geographic boundaries
*sometimes called lobar or multilobar pneumonia

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6
Q

healthcare associated pneumonia - general overview

A

*ventilator acquired pneumonia
*hospital acquired pneumonia
*some include patients in the community with a recent significant hospitalization
*some include nursing home patients
*MUST BE 72 HOURS AFTER ADMISSION to be considered hospital-acquired

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7
Q

typical pneumonia - general overview

A

*generally refers to bacterial lobar pneumonia

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8
Q

atypical pneumonia - general overview

A

*most describes less severe nonconsolidated pneumonia (i.e. mycoplasma, chlamydophila, some viruses, Q fever, etc)

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9
Q

tracheitis - general overview

A

*inflammation of the trachea, usually due to infection

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10
Q

bronchitis - general overview

A

*inflammation of bronchi (down to terminal bronchi)
*usually due to viruses (acute) or bacteria (chronic)

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11
Q

bronchiolitis - general overview

A

*inflammation of the small and terminal bronchi
*usually due to a virus

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12
Q

alveolitis - general overview

A

*inflammation usually limited to the alveoli
*often non-infectious

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13
Q

bronchopneumonia - general overview

A

*more of a radiographic term with pneumonia and adjacent bronchi demonstrating exudates

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14
Q

pulmonary abscess - general overview

A

*focal suppurative abscess in lung

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15
Q

pleuritis - general overview

A

*inflammation of the pleura due to infectious (usually viral) or non-infectious causes

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16
Q

empyema - general overview

A

*pleural space infection
*usually due to bacteria

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17
Q

pathophysiology of pneumonia

A

*bacteria introduced into the alveoli due to airway conduction (90%; aspiration of something) or blood (10%)
*accumulation of cells, fluid, sometimes RBCs, bacterial byproducts; collapse or inundation of alveoli
*small airways occlude with alveolar material and directly de to infectious process
*ventilation does not occur to perfused lung and hypoxia results
*also decreased lung compliance and decreased global ventilation

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18
Q

host defenses against pnuemonia

A

*normal swallowing and epiglottis protect the airways
*respiratory cilia
*airway mucous
*immunoglobulin and humeral immunity in epithelial/alveolar lining fluid
*alveolar macrophages
*NK and cellular immunity, particularly for some pathogens

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19
Q

possible complications of pneumonia

A

*severe sepsis/septic shock
*secondary bacteremia (occult vs. clinically apparent)
*metastatic infection (meningitis, septic arthritis, brain abscess)
*empyema/pulmonary abscess
*complications of hypoxia
*acute respiratory distress syndrome (ARDS)

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20
Q

community acquired pneumonia (CAP) - risk factors

A

*respiratory tract disease
*smoking
*alcohol abuse
*comorbidities (diabetes, heart, renal disease, etc)
*extremes of age
*immunodeficiency
*acid reducing drugs

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21
Q

community acquired pneumonia (CAP) - pathogenesis

A

*aspiration of upper airway bacteria (90%)
*hematogenous (10%) - usually S. aureus if so

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22
Q

community acquired pneumonia (CAP) - following viral infections (3 most common pathogens)

A

*CAP can follow viral infection, particularly influenza (loss of respiratory epithelial cells and ciliary functions)
*3 common pathogens:
1. Strep pneumoniae
2. Strep pyogenes
3. Staph aureus

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23
Q

community acquired pneumonia (CAP) - symptoms

A

*fever/chills
*cough (often productive)
*chest pain (often pleuritic)
*shortness of breath
*hypoxia
*symptoms due to severe sepsis/septic shock

24
Q

most common bacterial pathogens associated with community acquired pneumonia (CAP)

A
  1. Strep pneumoniae
  2. Haemophilus influenzae
  3. Moraxella caterrhalis
  4. Legionella pneumophilia
  5. Bordetella pertussis
25
Q

common pathogens of non-cell-wall bacterial community acquired pneumonia (CAP)

A
  1. Mycoplasma
  2. Chlamydophilia
26
Q

community acquired pneumonia (CAP): STREP PNEUMONIAE features

A

*aerobic encapsulated gram positive coccus in streptococcus family
*on gram stain of direct specimens:
-LANCET SHAPED gram positive (purple) diplococci
*alpha hemolytic
*major virulence factor = antiphagocytic polysaccharide capsule
*teichoic acid is proinflammatory

27
Q

community acquired pneumonia (CAP): STREP PNEUMO clinical infection

A

*main host defense: serospecific antibodies
*high colonization to infection rate due to antibody acquisition due to sensitization during colonization or prior infection
*can be minor self-limiting infection
*sometimes rapidly fatal (esp. in splenectomized patients)

28
Q

community acquired pneumonia (CAP): HAEMOPHILUS INFLUENZAE features

A

*small facultative anaerobic encapsulated short gram negative bacilli in Pasteurellaceae family
*on gram stain of direct specimens:
-small, short, gram negative (pink) rods / coccobacilli
*fastidious
*requires highly nutritious “chocolate” agar
*factors X and V required for growth

29
Q

community acquired pneumonia (CAP) - Moraxella catarrhalis

A

*H. flu “want-to-be”
*less virulent than H. flu
*pathophysiology and clinical features similar to H. flu

30
Q

diagnosis of community acquired pneumonia (CAP)

A

*CXR (CT usually not needed)
*baseline labs and pulse ox to determine need for hospitalization
*gram stain and culture of sputum, sterile body fluid/blood
*PCR of sputum or positive blood culture

31
Q

treatment for community acquired pneumonia (CAP)

A

*most common: beta-lactam (amoxicillin or ceftriaxone)
*“atypical” pneumonia (mycoplasma or chlamydia): azithromycin macrolide
*fluoroquinolone (moxifloxacin or levofloxacin) if they can’t take the others

32
Q

prevention of community acquired pneumonia (CAP)

A

*vaccination with 15 or 20 valent pneumococcal conjugate vaccine (all children, elderly, immunocompromised, and splenectomized)
*HiB vaccine (all children and splenectomized)

33
Q

community acquired pneumonia (CAP): LEGIONELLA PNEUMOPHILIA features

A

*very poor staining slender aerobic gram-negative (pink) rods
*fastidious
*requires special media for culture (BCYE agar); requires cysteine and iron salts for growth

34
Q

community acquired pneumonia (CAP): LEGIONELLA PNEUMOPHILIA risk factors

A

*older age
*lung disease
*kidney, liver, or heart disease
*immunocompromised
*cigarette smoking
*Etoh abuse

35
Q

community acquired pneumonia (CAP): LEGIONELLA PNEUMOPHILIA pathophysiology

A

*acquired by INHALATION OF DROPLET NUCLEI FROM AN INFECTED AEROSOL
*cooling towers, showers, spas, whirlpools, fountains, grocery store and flower show misters
*organism able to survive in hot water tanks (biofilms and intracellularly in amoebae)

36
Q

diagnosis for legionella pneumonia

A

*URINE ANTIGEN TEST: detection of serogroup 1 specific lipopolysaccharide antigens in urine

37
Q

treatment for legionella pneumonia

A

*macrolide (azithromycin), fluoroquinolone, or rifampin antibiotics
*supportive care, often in ICU

38
Q

mycoplasma pneumonia - epidemiology

A

*infection of older children and young adults
*can occur in epidemics in 6-8 year cycles
*colonizes the nose, throat, trachea, and lower airways of infected individuals
*spread via large respiratory droplets during coughing episodes

39
Q

chlamydophila pnemoniae

A

*sinusitis, pharyngitis, bronchitis, and pneumonia
*believed to be transmitted person to person by respiratory secretions
*causes “atypical” pneumonia

40
Q

diagnosis of mycoplasma/chlamydophila pneumonia

A

*too difficult to culture
*serology
*respiratory PCR

41
Q

treatment of mycoplasma/chlamydophila pneumonia

A

*macrolide (azithromycin), tetracycline, or fluoroquinolones
*NO BETA LACTAMS (because they do not have cell walls)

42
Q

hospital-acquired pneumonia - clinical course

A

*prototype is ventilator-acquired
*patients usually have underlying health care problems
*after 3-5 days of hospitalization and/or respiratory tract instrumentation, normal naso/oropharyngeal flora transition to enteric and water associated gram negative rods

43
Q

hospital-acquired pneumonia - common pathogens

A

*GNRs: serratia, klebsiella, E. coli, enterobacter, PSEUDOMONAS
*MRSA and other staph aureus
*note - drug resistance is a problem and must be taken into consideration

44
Q

hospital-acquired pneumonia: PSEUDOMONAS AERUGINOSA features

A

*nonfermentive slender aerobic gram negative rods
*grows fairly easily on blood agar media
*some strains produce pyocyanin, which is a GREEN PIGMENT
*has a characteristic MUSTY GRAPE ODOR
*found in moist, warm environmental soils, plant materials and water

45
Q

hospital-acquired pneumonia: diagnosis

A

*gram stain, culture of infected tissue, sputum, BAL, blood
*multiplex PCR of blood/sputum
*bronchoscopy sometimes needed for specimen acquisition

46
Q

treatment for hospital-acquired pneumonia (esp. pseudomonas)

A

*advanced anti-pseudomonal penicillins: PIPERACILLIN, TICARCILLIN (piperacillin/tazobactam, ticarcillin/clavulanate)
*cefipime (4th gen cephalosporin) also covers pseudomonas

47
Q

Bordetella pertussis (Whooping Cough)

A

*small aerobic, gram-negative coccobacilli
*diagnosed with PCR
*pathogenesis: inhalation of B. pertussis organisms → adherence to ciliated respiratory epithelial cells of upper respiratory tract and nasopharynx → local tissue damage → loss of ciliated protective respiratory cells → cough

48
Q

Bordetella pertussis - clinical features

A
  1. coughing paroxysms: series of vigorous coughs (10-15) occurring during a single expiration
  2. inspiratory “whoop”: inspiration with partially closed clottis
  3. post-tussive emesis
49
Q

diagnosis of bordetella pertussis

A

*PCR of nasopharyngeal swab

50
Q

treatment of bordetella pertussis

A

macrolide or fluorquinolone

51
Q

prevention of bordetella pertussis

A

*vaccination of children, adolescents, and now adults and pregnant women

52
Q

acute bronchitis

A

*almost always due to respiratory viruses
*self limited
*cough is the major symptom; sometimes with fever
*antibiotics not indicated

53
Q

acute bacterial exacerbations of chronic bronchitis (ABECB)

A

*inflammation of the airway due to infection, limited to larger airways
*a complication of COPD
*due to increase in bacterial load and inflammatory host response in patients with chronic bronchitis/COPD, usually following viral infections
*major pathogens: H. flu, Moraxella catarrhalis, sometimes strep pneumo
*important to treat only is persistent symptoms of increased amount and purulence of sputum
*treatment with 5 day course of doxycycline, amoxicillin, or sometimes fluoroquinolone

54
Q

tracheitis - common pathogen

A

*almost always due to S. aureus (usually MRSA)
*usually intubated, ventilated/tracheostomy patients with fever and increased purulent tracheal secretions
*treat with 7 days of vancomycin (confirm susceptibilities)

55
Q

empyema - common pathogens

A

*staph aureus > anaerobes > alpha hemolytic strep > GNRs
*usually seen on CT scan (enhancement of contrast in pleura)
*treatment = chest tube or surgical drainage

56
Q

lung abscess - common pathogens

A

*anaerobes, alpha hemolytic strep, sometimes staph
*2-4 months of antibiotics (clindamycin is a good choice)

57
Q

common pathogens affecting people with cystic fibrosis/bronchiectasis

A

*Pseudomonas aeuriginoa
*Burkholderia cepacia
*S. aureus, including MRSA