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PHRM 865 > Lower Respiratory Tract Infections > Flashcards

Lower Respiratory Tract Infections Flashcards

1
Q

What are the host defense mechanisms?

A

nasopharynx, trachea/bronchi, oropharynx, alveoli/terminal airways

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2
Q

Host defense mechanisms - nasopharnyx

A

nasal hair (net to capture bacteria), anatomy of upper airways, IgA secretion, mucociliary apparatus, fibronectin (bind to bacteria to prevent binding to host cells)

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3
Q

Host defense mechanisms - trachea/bronchi

A

cough, epiglottic reflex, anatomy of conducting airways, mucociliary apparatus, immunoglobulin
these reflexes decrease bacteria load

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4
Q

Host defense mechanisms - oropharynx

A

saliva, slough epithelial cells, complement production
get rid of attached bacteria

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5
Q

Host defense mechanisms - alveoli/terminal airways

A

alveolar lining fluid, cytokines, macrophages + PMNs, cell-mediated immunity
increase binding of bacteria to host cells

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6
Q

What happens when the body does not do its job?

A

pathogen-mediated
host interventions
defenses gone wrong
host disease states

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7
Q

Pathogen-mediated

A

surface adhesions, pili, exotoxins, enzymes (fight immune cells)
most significant

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8
Q

Host interventions

A

smoking, alcohol, altered level of consciousness, endotracheal tubes
alcochol and altered level of consciousness decrease the epiglottic reflex

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9
Q

Defenses gone wrong

A

alveolar macrophages: phagocytosis + cytokine release –> recruit neutrophils –> acidic and hypoxic environment –> reduced phagocytosis

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10
Q

Host disease states

A

immunosuppression, diabetes, asplenia, elderly

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11
Q

What is community acquired pneumonia?

A

pneumonia that developed outside of the hospital or within the first 48 hours of hospital admission

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12
Q

Community-acquired pneumonia pathogenesis

A

aspiration, aerosolization, bloodborne

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13
Q

Community-acquired pneumonia pathogenesis - aspiration

A

most common pathway for bacterial pneumonia; organisms usually cleared if host defenses functioning properly
disorders that impair consciousness and depress gag reflex results in increased inoculum

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14
Q

Community-acquired pneumonia pathogenesis - aerosolization

A

direct inhalation of pathogen
droplet nuclei = particles containing pathogen

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15
Q

Community-acquired pneumonia pathogenesis - bloodborne

A

translocate to pulmonary site; extremely unlikely

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16
Q

Which microorganism is the most common pathogen organism for CAP?

A

virus

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17
Q

What are the common bacterial pathogens for CAP?

A

streptococcus pneumoniae (most common) - GP
haemophilus influenzae - GN
atypical pathogens: mycoplasma pneumoniae, legionella pneumophila, chlamydia pneumonieae
staphylococcus aureus - GP

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18
Q

Streptococcus pneumoniae in CAP

A

increased prevalence and severity in certain patients: asplenia, DM, immunocompromised, HIV, chronic cardiopulmonary/renal disease
risk factors for drug resistance: age (<6 or >65), prior antibiotic therapy, co-morbid conditions, day care, recent hospitalization, and close quarters - penicillin resistance ~3%, macrolide ~40-50%

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19
Q

Mycoplasma pneumoniae in CAP

A

atypical bacteria - lacks cell wall
spread by person-to-person contact; 2-3 week incubation period followed by slow onset of sx: persistent, non-productive cough, fever, HA, sore throat, rhinorrhea, N/V, arthralgia
imaging: patchy, interstitial infiltrates

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20
Q

Legionella pneumophila in CAP

A

atypical pathogen - found in water + soil
spread by aerosolization
increased risk: older males, chronic bronchitis, smokers, and immunocompromised
multisystem involvement: high fevers, relative bradycardia, multi-lobar involvement, mental status change, increased LFTs + SCr

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21
Q

Staphylococcus aureus in CAP

A

low prevalence
risk factors for MRSA: ~2-14 days post-influenza, previous MRSA infection/isolation, previous hospitalization, previous use of IV antibiotics
important to get MRSA nasal PCR!!! - has 95-99% NEGATIVE predictive value for MRSA in CAP! - tells you we don’t have MRSA

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22
Q

Risk factors for certain pathogens - alcoholism

A

s. pneumoniae, anaerobes, k. pneumoniae

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23
Q

Risk factors for certain pathogens - COPD/smoker

A

s. pneumoniae, h. influenzae, moraxella cattarhalis, legionella spp

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24
Q

Risk factors for certain pathogens - post influenza pneumonia

A

s. pneumoniae, s. aureus, h. influenzae

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25
Q

Risk factors for certain pathogens - structural lung disease

A

p. aeruginosa, s. aureus

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26
Q

Risk factors for certain pathogens - recent antibiotic exposure

A

s. aureus, p. aeruginosa

27
Q

Clinical presentation of CAP

A

sudden onset of fever, chills, pleuritic chest pain, dyspnea, productive cough; gradual onset with lower severity for mycoplasma and clamydia pneumoniae
in elderly pts: classic sx may be absent (afebrile, mild leukocytosis) and more likely to have decrease in functional status, weakness, and mental status changes
vitals: febrile, tachycardia (HR > 100), hypotensive (SBP < 90), tachypnea (RR > 30)

28
Q

Chest radiography in CAP

A

recommended for all pts with suspicion for CAP
dense lobar consolidation or infiltrates = suspicion for bacterial origin
patchy, diffuse, intersitial infiltrates = atypical or viral pathogens

29
Q

Sputum characteristics in CAP

A

color, amount, consistency, and odor observed

30
Q

Microbiology testing and other markers for CAP

A

respiratory culture: controversial
blood culture: get 2 sets!
WBC with differential, SCr, BUN, electrolytes, LFTs, pulse oximetry, oxygen saturation (less than 90), urinary antigen tests (s. pneumoniae, legionella pneumophila), nasopharyngeal PCR swabs (MRSA)

31
Q

Severe CAP

A

septic shock requiring vasopressors - resp rate >/=30 bpm, multilobal infiltrates, confusion/disorientation
respiratory failure requiring mechanical ventilation - uremia (BUN >/=20 mg/dL), leukopenia (WBC < 4000 cell/uL), thrombocytopenia (Plt < 100,000/uL), hypothermia, hypotension requiring aggressive fluids

32
Q

Other tools for CAP

A

procalcitonin: biomarker typically elevated in presence of bacterial infection
should NOT be used to determine need for antibiotics for CAP
clinical prediction tools: pneumonia severity index, CURB-65

33
Q

CAP treatment - supportive measures

A

humidified oxygen (need O2 in blood), bronchodilators (open pathways), fluids, chest physiotherapy (beating on someone’s back)

34
Q

CAP empiric therapy - outpatient with no comorbidities

A

health outpatient adults WITHOUT comorbidities or risk factors for antibiotic resistance: amoxicillin, doxycycline, macrolide resistance (<25%) - azithromycin (do NOT use macrolide monotherapy)

35
Q

CAP empiric therapy - outpatient with comorbidities

A

outpatient adults with comorbidities: chronic heart, lung, or renal disease, DM, alcoholism, malignancy, asplenia, or immunosuppression
monotherapy: respiratory fluoroquinolone - levofloxacin or moxifloxacin
combo therapy: beta lactam + macrolide or doxycycline (more preferred due to resistance)
(beta lactams recommended: amoxicillin clavulanate, cefpodoxime, or cefuroxime)

36
Q

CAP empiric therapy - inpatient non-severe

A

no MRSA/pseudomonas aeruginosa risk factors
monotherapy: respiratory fluoroquinolone - levofloxacin, moxifloxacin
combo therapy: beta-lactam + macrolide
(beta-lactams recommended: ampicillin/sulbactam, ceftriaxone)

37
Q

CAP empiric therapy - inpatient severe

A

no MRSA/pseudomonas aeruginosa risk factors
combo therapy: respiratory fluoroquinolone + beta-lactam or beta-lactam + macrolide (recommend this one)
(beta-lactams recommended: ampicillin/sulbactam, ceftriaxone)

38
Q

CAP empiric therapy - inpatient if MRSA risk factors are present

A

risk factors: ~2-14 days post-influenza; previous MRSA respiratory infection/isolation; previous hospitalization and use of IV antibiotics within last 90 days
MRSA coverage: vancomycin or linezolid

39
Q

CAP empiric therapy - inpatient if pseudomonas aeruginosa risk factors are present

A

risk factors: previous pseudomonas aeruginosa respiratory infection; previous hospitalization and use of IV antibiotics within last 90 days
pseudomonas coverage: piperacillin/tazobactam, cefepime, meropenem

40
Q

What about corticosteroids in CAP?

A

not recommended with non-severe CAP, suggest not to use with severe CAP, suggest not to use for severe influenza pneumonia
only recommended when patient has CAP AND septic shock!

41
Q

Duration of CAP therapy

A

continue antibiotics until clinically stable for a min of 5 total days

42
Q

What is clinical stability?

A

temp </= 38 degrees celsius, HR </= 100 bpm, RR </= 24 bpm, SBP >/= 90 mmHg, arterial )2 saturation >/= 90%, baseline mental status

43
Q

Aspiration pneumonia

A

no definition to differentiate aspiration pneumonia vs pneumonia
recommend against anaerobic coverage unless lung abscess or empyema present

44
Q

What is hospital acquired pneumonia?

A

pneumonia occurring >/= 48 hrs after hospital admission

45
Q

What is ventilator-associated pneumonia?

A

pneumonia occurring >/= 48 hrs after endotracheal intubation

46
Q

HAP/VAP epidemiology and impact

A

HAP: one of the most common hospital-acquired infections
VAP: increases utilization of healthcare resources from prolonged length of mechanical ventilation and hospitalization

47
Q

HAP/VAP pathogenesis

A

micro-aspiration of oropharyngeal secretions that are colonized with bacteria
aspiration of esophageal/gastric contents
hemaogenous spread from another source
direct inoculation into airways via intubation
mechanical ventilation - endotracheal tube bypasses all host defenses and decreases LRT defenses

48
Q

Risk factors for HAP/VAP

A

advanced age, severity of comorbid diseases (uncontrolled A1c, asthma, COPD), duration of hospitalization, endotracheal intubation, nasogastric tube, altered mental status, surgery, previous antimicrobial therapy

49
Q

Diagnosis of HAP/VAP

A

no gold standard for diagnosis
timing: important for defining hospital-acquired infection, impacts choice of antibiotic (48hrs from admission)
typical presentation: new lung infiltrate + clinical signs/sx: new onset fever, purulent sputum, leukocytosis, decline in oxygenation

50
Q

Common pathogens for HAP/VAP

A

aerobic gram-negative bacilli: pseudomonas aeruginosa, enteric gram-negative bacilli, aceintobacter baumannii
staphylococcus aureus: MRSA great concern in this population

51
Q

Microbiology testing for HAP/VAP

A

respiratory cultures: obtain for all pts, non-invasive > invasive
blood cultures: obtain from all pts

52
Q

Risk factors for multi-drug resistant HAP

A

prior IV antibiotic use within 90 days

53
Q

Risk factors for multi-drug resistant VAP

A

prior IV antibiotic use within 90 days, septic shock at time of diagnosis, acute respiratory distress syndrome, acute renal replacement therapy, >/= 5 days hospitalization prior to diagnosis

54
Q

Risk factors for MDR in HAP/VAP - MRSA and pseudomonas aeruginosa

A

MRSA: prior IV antibiotic use within 90 days
pseudomonas: prior IV antibiotic use within 90 days; carbapenems, broad-spectrum beta-lactams, fluoroquinolones

55
Q

Empiric therapy principles for HAP/VAP

A

should be based on locacl distribution of pathogens and susceptibility (utilize yearly antibiogram)
goal: provide broad spectrum antibiotics while avoiding unnecessary harms of inappropriate coverage

56
Q

Empiric therapy - antibiotic choice for HAP/VAP - MRSA coverage

A

risk factors: typical risk factors for MRSA, ICUs where > 10-20% MRSA isolates, treatment where prevalence is unknown
vancomycin or linezolid

57
Q

Empiric therapy - antibiotic choice for HAP/VAP - pseudomonas aeruginosa coverage

A

risk factors for resistance: ICUs where >10% of isolates resistant, treatment where resistance rates are unknown
piperacillin-tazobactam, cefepime, imipenem, meropenem, or levofloxacin

58
Q

Empiric therapy - HAP - not at high risk for mortality

A

not at high risk for mortality: not on ventilatory support or septic shock
goal: provide coverage for MSSA + pseudomonas aeruginosa
piperacillin-tazobactam, cefepime, imipenem, meropenem, or levofloxacin

59
Q

Empiric therapy - HAP - not at high risk for mortality but MRSA risk

A

goal: provide coverage for MRSA + pseudomonas aeruginosa
piperacillin-tazobactam, cefepime, imipenem, meropenem, or levofloxacin PLUS vancomycin or linezolid

60
Q

Empiric therapy - HAP - high risk for mortality and MRSA risk

A

goal: provide coverage for MRSA + MDR pseudomonas aeruginosa
pick 2 different classes: piperacillin-tazobactam, cefepime, imipenem, meropenem, levofloxacin, or tobramycin/amikacin (should be 1 beta-lactam and 1 non-beta-lactam) PLUS vancomycin or linezolid

61
Q

Empiric therapy - VAP

A

goal: provide coverage for MRSA + pseudomonas aeruginosa
when to choose 2 anti-pseudomonals: risk factors for resistance
piperacillin-tazobactam, cefepime, imipenem, meropenem, levofloxacin, or tobramycin/amikacin PLUS vancomycin or linezolid

62
Q

Non-beta lactam considerations

A

NEVER use daptomycin for LRTIs
aminoglycosides recommended against as monotherapy
tigecycline associated with increased mortality

63
Q

Duration for HAP/VAP

A

recommend 7-day duration if clinically stable

PHRM 865 (31 decks)

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