RESP 23: HAP

Question 1

What is the criteria for hospital-acquired pneumonia?

Answer 1

pneumonia developing > 48 hr after admission to hospital

Question 2

What is the criteria for early onset hospital-acquired pneumonia?

Answer 2

occurring within first 96 hours (< 5 days) of hospitalization

Question 3

What is the criteria for late onset hospital-acquired pneumonia?

Answer 3

occurring after more than 96 hours (≥ 5 days) of hospitalization

Question 4

Describe the pathophysiology of HAP.

Answer 4

• colonization of oropharyngeal tract → microaspiration of oropharyngeal contents
• hematogenous spread (less common)

Question 5

What are the risk factors for HAP?

Answer 5

• advanced age (> 70)
• coma
• COPD
• alcoholism
• CNS dysfunction
• sedatives/narcotics
• corticosteroid and cytotoxic agents
• surgery
• nasogastric tubes
• colonization of respiratory and GI tract with pathogenic microorganisms – previous/current antimicrobial therapy, endotracheal intubation, smoking, malnutrition, surgery, dental plaque, gastic acid suppression

Question 6

What are the usual pathogens for early onset OR no recent (past 90 days) antimicrobial use AND mild to moderate presentation?

Answer 6

• Streptococcus spp.
• Haemophilus influenzae
• Enterobacter spp.
• Escherichia coli
• Klebsiella spp.
• Proteus spp.
• Serratia marcescens
• Methicillin susceptible Staphylococcus aureus

Question 7

What are the usual pathogens for late onset OR recent antimicrobial use AND mild to moderate presentation?

Answer 7

same as above AND:

• Methicillin resistant S. aureus (MRSA)
• Pseudomonas aeruginosa

Question 8

What are the usual pathogens for severe presentation (hypotension, intubation, sepsis, rapid progression of infiltrates, end organ failure)?

Answer 8

same as above AND:

• Legionella spp.

Question 9

What are the diagnostic criteria for HAP?

Answer 9

need both of:

• abnormal findings on chest radiograph
• at least 2 of: fever, leukocytosis, purulent tracheal secretions

features can also be found in other conditions – heart failure, pulmonary embolis, pulmonary hemorrhage, malignancy, pulmonary drug reactions, etc.

Question 10

Describe the vital signs of HAP.

Answer 10

• fever
• increased RR
• increased oxygen requirements

Question 11

Describe the respiratory clinical presentation of HAP.

Answer 11

• SOB, pleuritic chest pain, cough +/- sputum production
• physical exam: dullness to percussion, decreased air entry, crackles on auscultation
• radiology: new pulmonary infiltrates on chest radiograph

Question 12

Describe other clinical presentations of HAP.

Answer 12

• increased WBC
• confusion, anorexia, nausea, vomiting
• sepsis (hypotension, end organ dysfunction, lactic acidosis, etc.) in around 10% of cases

Question 13

What are the risk factors for resistance?

Answer 13

• hospitalization for at least 5 days (ie. late onset)
• receipt of antimicrobial therapy in previous 90 days

Question 14

What are the risk factors for MRSA?

Answer 14

• prior detection of MRSA (on culture or screening)
• treatment in unit where prevalence of MRSA amongst S. aureus isolates is > 20%
• persons who inject drugs (PWID), hemodialysis patients, skin disease, venous catheters, other foreign bodies (ie. pacemakers), surgical procedures, hospitalization

Question 15

What are the risk factors for Pseudomonas?

Answer 15

• mechanical ventilation
• history of COPD
• cystic fibrosis and bronchiectasis

Question 16

PK/PD Considerations in Pneumonia

Daptomycin

Answer 16

well known to be sequestered by pulmonary surfactant, resulting in inactivation of drug

Question 17

PK/PD Considerations in Pneumonia

Answer 17

current knowledge of PK/PD of antimicrobials in lung tissue based on concentration of drug in epithelial lung fluid (ELF)

• macrolides, fluoroquinolones, oxazolidinones have ELF:plasma ratios > 1
• beta-lactams, aminoglycosides, and glycopeptides have ELF:plasma ratios < 1
• clinical significance of ELF:plasma ratios not well-understood

Question 18

What is the empiric therapy for patients NOT at high risk of mortality and no risk for resistance (mild presentation)?

Answer 18

• amoxicillin-clavulanate 875 mg PO BID
• ceftriaxone 1 g IV q24h
• if severe beta-lactam allergy: moxifloxacin 400 mg pO/IV q24h

Question 19

What is the empiric therapy for patients with moderate presentation or risk factors for resistance?

Answer 19

• piperacillin-tazobactam 3.375 g IV q6h
• if severe beta-lactam allergy: meropenem 500 mg IV q6h
• if MRSA known/suspected: consider adding vancomycin 15 mg/kg IV q12h – adjusted for target trough concentration of 10-20 mg/L (in BC 10-15 mg/L)

Question 20

What is the empiric therapy for patients at high risk of mortality?

Answer 20

• piperacillin-tazobactam 3.375 g IV q6h
• if severe beta-lactam allergy: meropenem 500 mg IV q6h
• if MRSA known/suspected: consider adding vancomycin

Question 21

Is combination therapy for Pseudomonas infections recommended?

Answer 21

no – but can be considered in critically ill patients to improve likelihood that pathogen is covered by at least one agent (step-down to monotherapy once susceptibilities are known)

Question 22

What is the recommended duration of therapy for HAP?

Answer 22

7 days

Question 23

What are the monitoring parameters of pneumonia?

Answer 23

• clinical symptoms
• labs – normalization of leukocytosis, clearance of blood cultures if associated bacteremia
• repeat chest radiography is generally NOT recommended due to lag in radiographic changes

Question 24

What is ventilator-associated pneumonia (VAP)?

Answer 24

• subset of HAP
• pneumonia in patient mechanically ventilated for > 48 hours

Question 25

What is the clinical presentation of VAP?

Answer 25

pneumonia in patient mechanically ventilated for > 48 hours with: at least 2 of: - temperature > 38.3ºC - leukocytosis or leukopenia - purulent tracheal secretions at least 1 of: - new or persistent infiltrates on chest radiographs - isolation of same microorganism from pleural fluid and tracheal secretions - radiographic cavitation - histopathological demonstration of pneumonia and positive cultures obtained from bronchoalveolar lavage

Question 26

What does mechanical ventilation reverse?

Answer 26

- hypoxemia - respiratory acidosis

Question 27

Describe the pathophysiology of VAP?

Answer 27

- HAP pathophysiology - leakage of endotracheal secretions around endotracheal cuff → aspiration of endotracheal secretions

Question 28

What are the usual pathogens if early onset OR no recent (past 90 days) antimicrobial use AND mild to moderate presentation?

Answer 28

- Streptococcus spp. - Haemophilus influenzae - Enterobacter spp. - Escherichia coli - Klebsiella spp. - Proteus spp. - Serratia marcescens - Methicillin susceptible Staphylococcus aureus

Question 29

What are the usual pathogens if late onset OR recent antimicrobial use AND/OR severe presentation?

Answer 29

same as above AND: - Methicillin resistant S. aureus (MRSA) - Pseudomonas aeruginosa - Legionella species - Acinetobacter species - Stenotrophomonas maltophilia

Question 30

What is the management for VAP?

Answer 30

same as HAP

Question 31

What is aspiration pneumonia?

Answer 31

- seen in both community and hospital settings, however hospitalization can put patient at higher risk for aspiration - large volume aspiration (macroaspiration) is main component of aspiration pneumonia

Question 32

What is aspiration?

Answer 32

inhalation of oropharyngeal or gastric contents into larynx and lower respiratory tract

Question 33

What are the risk factors for aspiration pneumonia?

Answer 33

- impaired swallowing – esophageal disease (dysphagia, cancer, stricture), COPD, neurologic diseases (seizures, multiple sclerosis, Parkinson’s, stroke, dementia), mechanical ventilation extubation - decreased level of consciousness – neurologic disease, cardiac disease, medications (sedatives), general anesthesia, alcohol consumption - increased chance of gastric contents reaching lungs – reflux, tube feeding - impaired cough reflex – medications, alcohol, stroke, dementia, degenerative neurologic disease, impaired consciousness - medication – sedative or anesthetic agents, anticholinergics, calcium channel blockers

Question 34

Describe the difference between chemical pneumonitis and aspiration pneumonia.

Answer 34

- macroaspiration of sterile gastric/oropharyngeal contents → chemical pneumonitis - macroaspiration of pathogenic bacteria from orophayngeal or gastric contents → aspiration pneumonia

Question 35

What are the usual pathogens for chemical pneumonitis?

Answer 35

sterile

Question 36

What are the usual pathogens for aspiration pneumonia?

Answer 36

polymicrobial - S. aureus - S. pneumoniae - H. influenzae - Enterobacteraciae - oral anaerobes - anaerobes (?)

Question 37

Why might it be difficult to distinguish between chemical pneumonitis and aspiration pneumonia?

Answer 37

can have very similar clinical and radiographic presentations

Question 38

Describe the clinical presentation of aspiration pneumonia.

Answer 38

abrupt onset and resolution, with fever and hypoxemia resolving within 24 hours

Question 39

What is the therapy for chemical pneumonitis?

Answer 39

supportive – antibiotics not indicated

Question 40

What is the therapy for aspiration pneumonia?

Answer 40

- ceftriaxone 1 g IV q24h - if: severe illness: piperacillin-tazobactam 3.375 g IV q6h - if: MRSA known/suspected: add vancomycin severe beta-lactam allergy: moxifloxacin 400 mg PO/IV q24h - oral stepdown and duration - duration of therapy 5-7 days - anaerobic coverage can be added to ceftriaxone if subacute onset, putrid sputum, lung abscess, necrotizing pneumonia, empyema: metronidazole 500 mg PO/IV q12h