Infections of the Lower Respiratory System Flashcards
clinical classifications of lower respiratory tract infections
*pneumonitis
*pneumonia
*community acquired pneumonia
*consolidative pneumonia
*healthcare associated pneumonia
*typical pneumonia
*atypical pneumonia
*tracheitis
*bronchitis
*bronchiolitis
*alveolitis
*bronchopneumonia
*pulmonary abscess
*pleurits
*empyema
pneumonitis - general overview
*inflammation of the lung resulting in acute/subacute/chronic disease
*many causes of pneumonitis are not infectious (i.e. hypersensitivity, autoimmune, vasculitis, chemical, etc)
pneumonia - general overview
*pneumonitis due to viral, bacterial, or parasitic causes
community acquired pneumonia - general overview
*pneumonia arising in an individual in the community (not in a healthcare or long-term care setting)
consolidative pneumonia - general overview
*seen on CXR as dense alveolar infiltrate with lobar geographic boundaries
*sometimes called lobar or multilobar pneumonia
healthcare associated pneumonia - general overview
*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
typical pneumonia - general overview
*generally refers to bacterial lobar pneumonia
atypical pneumonia - general overview
*most describes less severe nonconsolidated pneumonia (i.e. mycoplasma, chlamydophila, some viruses, Q fever, etc)
tracheitis - general overview
*inflammation of the trachea, usually due to infection
bronchitis - general overview
*inflammation of bronchi (down to terminal bronchi)
*usually due to viruses (acute) or bacteria (chronic)
bronchiolitis - general overview
*inflammation of the small and terminal bronchi
*usually due to a virus
alveolitis - general overview
*inflammation usually limited to the alveoli
*often non-infectious
bronchopneumonia - general overview
*more of a radiographic term with pneumonia and adjacent bronchi demonstrating exudates
pulmonary abscess - general overview
*focal suppurative abscess in lung
pleuritis - general overview
*inflammation of the pleura due to infectious (usually viral) or non-infectious causes
empyema - general overview
*pleural space infection
*usually due to bacteria
pathophysiology of pneumonia
*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
host defenses against pnuemonia
*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
possible complications of pneumonia
*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)
community acquired pneumonia (CAP) - risk factors
*respiratory tract disease
*smoking
*alcohol abuse
*comorbidities (diabetes, heart, renal disease, etc)
*extremes of age
*immunodeficiency
*acid reducing drugs
community acquired pneumonia (CAP) - pathogenesis
*aspiration of upper airway bacteria (90%)
*hematogenous (10%) - usually S. aureus if so
community acquired pneumonia (CAP) - following viral infections (3 most common pathogens)
*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
community acquired pneumonia (CAP) - symptoms
*fever/chills
*cough (often productive)
*chest pain (often pleuritic)
*shortness of breath
*hypoxia
*symptoms due to severe sepsis/septic shock
most common bacterial pathogens associated with community acquired pneumonia (CAP)
- Strep pneumoniae
- Haemophilus influenzae
- Moraxella caterrhalis
- Legionella pneumophilia
- Bordetella pertussis
common pathogens of non-cell-wall bacterial community acquired pneumonia (CAP)
- Mycoplasma
- Chlamydophilia
community acquired pneumonia (CAP): STREP PNEUMONIAE features
*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
community acquired pneumonia (CAP): STREP PNEUMO clinical infection
*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)
community acquired pneumonia (CAP): HAEMOPHILUS INFLUENZAE features
*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
community acquired pneumonia (CAP) - Moraxella catarrhalis
*H. flu “want-to-be”
*less virulent than H. flu
*pathophysiology and clinical features similar to H. flu
diagnosis of community acquired pneumonia (CAP)
*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
treatment for community acquired pneumonia (CAP)
*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
prevention of community acquired pneumonia (CAP)
*vaccination with 15 or 20 valent pneumococcal conjugate vaccine (all children, elderly, immunocompromised, and splenectomized)
*HiB vaccine (all children and splenectomized)
community acquired pneumonia (CAP): LEGIONELLA PNEUMOPHILIA features
*very poor staining slender aerobic gram-negative (pink) rods
*fastidious
*requires special media for culture (BCYE agar); requires cysteine and iron salts for growth
community acquired pneumonia (CAP): LEGIONELLA PNEUMOPHILIA risk factors
*older age
*lung disease
*kidney, liver, or heart disease
*immunocompromised
*cigarette smoking
*Etoh abuse
community acquired pneumonia (CAP): LEGIONELLA PNEUMOPHILIA pathophysiology
*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)
diagnosis for legionella pneumonia
*URINE ANTIGEN TEST: detection of serogroup 1 specific lipopolysaccharide antigens in urine
treatment for legionella pneumonia
*macrolide (azithromycin), fluoroquinolone, or rifampin antibiotics
*supportive care, often in ICU
mycoplasma pneumonia - epidemiology
*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
chlamydophila pnemoniae
*sinusitis, pharyngitis, bronchitis, and pneumonia
*believed to be transmitted person to person by respiratory secretions
*causes “atypical” pneumonia
diagnosis of mycoplasma/chlamydophila pneumonia
*too difficult to culture
*serology
*respiratory PCR
treatment of mycoplasma/chlamydophila pneumonia
*macrolide (azithromycin), tetracycline, or fluoroquinolones
*NO BETA LACTAMS (because they do not have cell walls)
hospital-acquired pneumonia - clinical course
*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
hospital-acquired pneumonia - common pathogens
*GNRs: serratia, klebsiella, E. coli, enterobacter, PSEUDOMONAS
*MRSA and other staph aureus
*note - drug resistance is a problem and must be taken into consideration
hospital-acquired pneumonia: PSEUDOMONAS AERUGINOSA features
*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
hospital-acquired pneumonia: diagnosis
*gram stain, culture of infected tissue, sputum, BAL, blood
*multiplex PCR of blood/sputum
*bronchoscopy sometimes needed for specimen acquisition
treatment for hospital-acquired pneumonia (esp. pseudomonas)
*advanced anti-pseudomonal penicillins: PIPERACILLIN, TICARCILLIN (piperacillin/tazobactam, ticarcillin/clavulanate)
*cefipime (4th gen cephalosporin) also covers pseudomonas
Bordetella pertussis (Whooping Cough)
*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
Bordetella pertussis - clinical features
- coughing paroxysms: series of vigorous coughs (10-15) occurring during a single expiration
- inspiratory “whoop”: inspiration with partially closed clottis
- post-tussive emesis
diagnosis of bordetella pertussis
*PCR of nasopharyngeal swab
treatment of bordetella pertussis
macrolide or fluorquinolone
prevention of bordetella pertussis
*vaccination of children, adolescents, and now adults and pregnant women
acute bronchitis
*almost always due to respiratory viruses
*self limited
*cough is the major symptom; sometimes with fever
*antibiotics not indicated
acute bacterial exacerbations of chronic bronchitis (ABECB)
*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
tracheitis - common pathogen
*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)
empyema - common pathogens
*staph aureus > anaerobes > alpha hemolytic strep > GNRs
*usually seen on CT scan (enhancement of contrast in pleura)
*treatment = chest tube or surgical drainage
lung abscess - common pathogens
*anaerobes, alpha hemolytic strep, sometimes staph
*2-4 months of antibiotics (clindamycin is a good choice)
common pathogens affecting people with cystic fibrosis/bronchiectasis
*Pseudomonas aeuriginoa
*Burkholderia cepacia
*S. aureus, including MRSA
