Tutorial 2: Pneumonia Flashcards
What is CAP?
community-acquired pneumonia: acute infection of the pulmonary parenchyma acquired outside of the hospital
What are the two categories of nosocomial pneumonia?
hospital-acquired pneumonia (HAP)
ventilator-associated pneumonia (VAP)
What is HAP?
hospital-acquired pneumonia: pneumonia acquired ≥48 hours after hospital admission, and did not appear to be incubating at the time of admission.
What is VAP?
ventilator-associated pneumonia: pneumonia acquired ≥48 hours after endotracheal intubation.
What was HCAP, and how is it treated now?
Health care-associated pneumonia; currently treated as CAP
Referred to pneumonia acquired in health care facilities (eg, nursing homes, hemodialysis centers) or after recent hospitalization
What are the non-modifiable (/less modifiable) risk factors for pneumonia?
- Older age (≥65)
- Chronic comorbidities
- Viral respiratory tract infection
- Impaired airway protection (LOC, dysphagia)
What chronic comorbidities are risk factors for CAP?
COPD (comorbidity with highest risk for hospitalization)
- other chronic lung disease (bronchiectasis, asthma)
- CHF and other chronic heart disease
- stroke
- DM
- malnutrition
- immunocompromise
Once you have one risk factor for CAP, does having more increase your risk?
Yes: risk factors are additive
eg CHF, smoking, COPD
What are the three categories of most common causes of CAP?
Typical bacteria
Atypical bacteria
Respiratory viruses
What is the single most common bacterial cause of pneumonia?
Streptococcus pneumoniae (pneumococcus)
What pathogens are “typical bacterial” causes of CAP? (7 listed)
- S. pneumoniae (most common bacterial cause)
- Haemophilus influenzae
- Moraxella catarrhalis
- Staphylococcus aureus
- Group A streptococci
- Aerobic gram-negative bacteria (eg, Enterobacteriaceae such as Klebsiella spp or Escherichia coli)
- Microaerophilic bacteria and anaerobes (associated with aspiration)
What pathogens are “atypical bacterial” causes of CAP? (5 listed)
- Legionella spp
- Mycoplasma pneumoniae
- Chlamydia pneumoniae
- Chlamydia psittaci
- Coxiella burnetii
What defines “atypical” bacterial causes of CAP?
- resistant to beta-lactams
- can’t be visualized on Gram stain or cultured using traditional techniques
What respiratory viruses cause CAP? (8 listed)
- Influenza A and B viruses
- Rhinoviruses
- Parainfluenza viruses
- Adenoviruses
- Respiratory syncytial virus
- Human metapneumovirus
- Coronaviruses (eg, Middle East respiratory syndrome coronavirus)
- Human bocaviruses
What features are associated with CAP due to community acquired MRSA?
Necrotizing or cavitary pneumonia Empyema Gross hemoptysis Septic shock Respiratory failure
What recent discovery has changed our understanding of pneumonia?
Lung microbiome: lung parenchyma was previously thought to be sterile
e.g. change from pathogen colonization of sterile lung to pathogen competition with microbiome – and dysbiosis as a risk factor for pneumonia
What are the most common symptoms associated with CAP?
- Cough (with or without sputum production)
- dyspnea
- pleuritic chest pain
What are the most common physical exam findings associated with CAP?
- tachypnea (RR > 24: 45-70%; most sensitive sign in older pt)
- increased WOB
- adventitious breath sounds, including rales/crackles (about 1/3 of pt) and rhonchi
- fever (80%, though freq absent in older pt)
Tactile fremitus, egophony, and dullness to percussion also suggest pneumonia.
What is the gold standard for diagnosis of pneumonia?
Infiltrate on CXR, in context of supportive clinical syndrome (eg, fever, dyspnea, cough, and sputum production)
What are the most common lab findings associated with CAP?
- CBC: Leukocytosis (15-30), leftward shift
- leukopenia can occur; generally poor prognosis
- inflammatory markers (CRP< ESR, procalcitonin)
What other features might CAP present with (not most common, but not rare)?
- GI (N/V/D)
- MS changes
What features on CXR are consistent with CAP?
- lobar consolidations
- interstitial infiltrates
- cavitations
What if the CXR is negative, but you still really suspect pneumonia based on clinical picture?
CT
Esp if immunocompromised (less infl response so less infiltrate) or known exposure to pathogen that causes pneumonia (eg legionella)
Name 2 score tools used to calculate mortality and determine site of treatment for CAP
PSI (Pneumonia Severity Index), aka PORT score
CURB-65
When do you treat a pt with CAP as ambulatory?
Otherwise healthy
Normal vital signs aside from fever
No concern for complication
When do you admit a pt with CAP?
SpO2 <92% on RA (sig change from baseline)
Also consider for practical concerns like inability to take oral meds, functional impairment, social issues affecting adherence or followup
What groups are not well represented in CAP scoring, and should be considered for admission even with mild scores?
patients with early signs of sepsis, rapidly progressive illness, or suspected infections with aggressive pathogens
When do you admit a pt to ICU for CAP?
- respiratory failure requiring mechanical ventilation
- sepsis requiring vasopressor support
What criteria support early ICU admission, due to anticipated progression to sepsis? (name 5; 9 listed)
Three of:
- AMS
- Hypotension requiring fluids
- T < 36
- RR ≥ 30
- PaO2/FiO2 ratio ≤250
- BUN ≥ 7 mmol/L
- Leukocyte count <4
- Platelet count <100
- Multilobar infiltrates
What microbiologic testing of CAP should be performed in outpatients?
Outpt: none – empiric Abx good
What microbiologic testing of CAP should be performed in inpatients?
- Blood cultures
- Sputum Gram stain and culture
- other tests based on risk factors, epidemiology, exposures (eg immunocompromised? PCJ, fungal, parasites, CMV)
[suspect these may be US-specific:]
- Urinary antigen testing for S. pneumoniae
- Testing for Legionella spp (polymerase chain reaction [PCR] when available, urinary antigen test as an alternate)-
- consider flu test
What else is on the DDx for CAP?
Present with pulmonary infiltrate and cough:
- Congestive heart failure with pulmonary edema
- Pulmonary embolism
- Pulmonary hemorrhage
- Atelectasis
- Aspiration or chemical pneumonitis
- Drug reactions
- Lung cancer
- Collagen vascular diseases
- Vasculitis
- Acute exacerbation of bronchiectasis
- Interstitial lung diseases (eg, sarcoidosis, asbestosis, hypersensitivity pneumonitis, cryptogenic organizing pneumonia)
How long do pulmonary infiltrates due to pneumonia take to resolve?
Weeks: if resolving in days, consider alternate Dx
What are the features of the CURB-65 score?
- Confusion
- BUN > 7 mmol/L
- RR ≥ 30
- Systolic BP < 90 mmHg or Diastolic BP ≤ 60 mmHg
- Age ≥ 65
1 point outpt, 2 inpt or close f/u, 3+ inpt
What do empiric treatment regimens for outpt CAP target?
S. pneumoniae
Atypical pathogens
When would you expand your empiric coverage for outpt CAP?
- comorbidities
- smoking
- recent Abx
When would you expand your empiric coverage for outpt CAP even further?
Structural lung disease
What would expansion of empiric coverage for outpt CAP target?
beta-lactamase-producing H. influenzae, M. catarrhalis, and methicillin-susceptible S. aureus
What would further expansion of empiric coverage for outpt CAP target?
Enterobacteriaceae, such as E. coli and Klebsiella spp
What is the initial empiric Abx regimen for pt with outpt CAP who are <65 years, otherwise healthy, and have not recently used antibiotics?
amoxicillin 1g TID
+
macrolide (eg azithromycin) or doxycycline
(macrolide preferred)
Some recommend amoxicillin alone to start
What is the initial empiric Abx regimen for pt with outpt CAP with
- comorbidities
- smoking
- recent Abx?
oral extended-release amoxicillin-clavulanate (2 g twice daily)
+
macrolide (eg azithromycin) or doxycycline
(macrolide preferred)
What is the alternative to amoxicillin-based regimens?
- combination therapy with a cephalosporin plus a macrolide or doxycyclin
or, - monotherapy with lefamulin.
How long should you treat pt with outpt CAP with Abx?
5d, up to 7d; should be improving, and be afebrile for at least 48h before stopping
What do empiric treatment regimens for CAP treated as an inpt target?
- typical pathogens (eg, S. pneumoniae, H. influenzae, and M. catarrhalis)
- atypical pathogens (eg, Legionella pneumophilia, M. pneumoniae, and C. pneumoniae)
- S. aureus
- gram-negative enteric bacilli (eg, Klebsiella pneumoniae)
What are the key factors in selecting an initial Abx regimen for inpt with CAP?
Risk of Pseudomonas and/or methicillin-resistant S. aureus (MRSA)
What is the initial empiric Abx regimen for pt with inpt CAP without suspicion for MRSA or Pseudomonas?
combination therapy:
beta-lactam + macrolide
or
beta-lactam + fluoroquinolone
What is the initial empiric Abx regimen for pt with inpt CAP with
- known colonization with pseudomonas
- recent hospitalization with Abx use
- other strong suspicion for pseudomonas?
antipseudomonal beta-lactam + antipseudomonal fluoroquinolone (eg, ciprofloxacin or levofloxacin).
What are the antipseudomonal beta lactams? (5 listed)
piperacillin-tazobactam cefepime ceftazidime meropenem imipenem
What are the antipseudomonal fluoroquinolones? (2 listed)
Ciprofloxacin
levofloxacin
What is the initial empiric Abx regimen for pt with inpt CAP with
- known colonization or prior infection with MRSA
- other strong suspicion for MRSA?
Treatment for non-pseudo/non-MRSA, or treatment for suspect MRSA,
+
agent with anti-MRSA activity, such as vancomycin or linezolid
(Linezolid preferred for suspected community acquired MRSA)
What are the risk factors for MRSA?
known MRSA colonization or prior MRSA infection
- recent antibiotic use (esp IV w/in last 3mo)
- recent influenza-like illness
- the presence of empyema
- necrotizing/cavitary pneumonia
- immunosuppression
What are the risk factors for community acquired MRSA?
- history of MRSA skin lesions
- participation in contact sports
- injection drug use
- crowded living conditions
- men who have sex with men
What are the risk factors for pseudomonas?
- known colonization or prior infection with Pseudomonas spp
- recent hospitalization or antibiotic use
- underlying structural lung disease (eg, CF or advanced COPD [bronchiectasis])
- immunosuppression.
When should you give adjunctive glucocorticoids in CAP?
Evidence not clear: generally, don’t.
Consider in pt with CAP with exaggerated or dysregulated host inflammatory response (refractory septic shock–look up criteria if it gets to this point).
What subjective features should you monitor in pt with CAP?
- cough
- sputum production
- dyspnea
- chest pain
What objective features should you monitor in pt with CAP?
- temp
- HR
- RR
- oxygenation
- WBC
How soon after treatment initiation do pt with CAP demonstrate improvement?
Generally, patients demonstrate some clinical improvement within 48 to 72 hours
When should you discharge a pt who was admitted with CAP?
- clinically stable
- can take oral medication
- no other active medical problems
- safe environment for continued care
What should you consider when managing immunocompromised patients presenting with presumed CAP?
- can have different kinds of infections (eg fungal, PCP)
- multiple infections can co-occur
- SSx can be subtle and nonspecific
Consider involving multidisciplinary team.
Why consider involving multidisciplinary team when managing immunocompromised patients presenting with presumed CAP?
- management is complex
- drug interactions are common
- adjustments in immunosuppressive regimens may be needed
- empiric treatment options can be associated with significant toxicity
Should followup CXR be obtained to ensure pneumonia is resolved?
Most pt don’t need it if Sx are resolving within 5-7d.
Radiographic response lags behind clinical response.
What are the two general categories of the ways patients with CAP fail clinically?
- progression of initial infection
- development of comorbid complications (eg HAP, C diff, CV events)
If pt don’t resolve within 5-7d with empiric ABx, they have non-resolving CAP. What are the main subcategories of non-resolving CAP?
- delayed clinical response
- loculated infection (abscess, empyema, other)
- bronchial obstruction
- Pathogens that cause subacute/chronic CAP (eg TB)
- Incorrect initial Dx
What is the mortality for CAP?
Range. 30 day mortality for…
- Ambulatory: <1%
- Severe: 20-25%
What are the key strategies to prevent CAP? (3 listed)
Smoking cessation (when appropriate)
Influenza vaccination for all patients
Pneumococcal vaccination for at-risk patients
What are most CAP caused by?
Streptococcus pneumoniae and respiratory viruses
What are the categories of antimicrobial-resistant gram-negative bacilli according to the US and European CDCs?
Multidrug resistant (MDR) Extensively drug resistant (XDR) Pandrug resistant (PDR)
What is the definition of Multidrug resistant?
acquired nonsusceptibility to at least one agent in three different antimicrobial classes.
What is the definition of extensively drug resistant?
nonsusceptibility to at least one agent in all but two antimicrobial classes.
What is the definition of pandrug resistant?
nonsusceptibility to all antimicrobial agents that can be used for treatment.
What proportion of healthy adults aspirate during sleep?
Approx 45%
What is the primary route of lung infection?
microaspiration of organisms that have colonized the oropharyngeal tract (or, to a lesser extent, the gastrointestinal tract)
What are common pathogens for HAP and VAP?
aerobic gram-negative bacilli (eg, Escherichia coli, Klebsiella pneumoniae, Enterobacter spp, Pseudomonas aeruginosa, Acinetobacter spp)
gram-positive cocci (eg, Staphylococcus aureus, including methicillin-resistant S. aureus [MRSA], Streptococcus spp)
Viruses, fungi becoming increasingly recognized
How is HAP diagnosed?
clinical diagnosis:
new lung infiltrate
+
clinical evidence that the infiltrate is of infectious origin: new fever, purulent sputum, leukocytosis, decline in oxygenation
What ventilator-specific findings might be present in someone with VAP?
Ventilator mechanics: reduced tidal volume, increased inspiratory pressures
Name 3 common radiographic abnormalities in VAP
alveolar infiltrates, air bronchograms, and silhouetting of adjacent solid organs
What diagnostic test should be performed in patients with suspected VAP?
Respiratory tract sample for microscopy and culture
Experts differ re invasive (eg bronchoalveolar lavage) vs noninvasive (eg aspiration) and quantitative vs non-quantitative
What does microscopic analysis of respiratory tract samples tell you in VAP?
semi-quantitative analysis of polymorphonuclear leukocytes and other cell types, as well as the Gram stain.
Can be helpful in determining a possible pathogen and alter antibiotic selection
How is VAP diagnosed?
new lung infiltrate
+
clinical evidence that the infiltrate is of infectious origin: new fever, purulent sputum, leukocytosis, decline in oxygenation
+
resp sample positive (increased neutrophils and growth of a pathogen in culture)
What is the DDx for VAP?
Aspiration pneumonitis PE with infarction ARDS Pulmonary hemorrhage Lung contusion Infiltrative tumour Radiation pneumoniitis Drug reaction Cryptogenic organizing pneumonia Vasculitis (eg SLE)
What is the role of procalcitonin in VAP?
Suspected VAP: Conflicting evidence
Confirmed VAP: May be useful for discontinuing Abx and prognosis
What factors, on top of risk factors for CAP, put pt at risk of VAP?
Biggest is mechanical ventilation (obviously)
Others: Chest or upper abdo surgery, agents that increase gastric pH, previous Abx exposure, reintubation or prolonged intubation, frequent vent circuit changes; many more
What strategies can prevent aspiration in a ventilated pt?
Positioning: head of bed at 30-45 degrees
Subglottic draining (of secretions)
Gastric volume monitoring
What GI intervention can prevent pneumonia in critically ill pt? How is it done?
Decontamination of digestive tract
- oropharyngeal antiseptics (eg chlorhexidine)
- selective decontamination (oropharyngeal non-absorbed Abx)
How are stress-dose glucocorticoids used in critically ill pt?
Not clear; further study needed.
What does the empiric regimen for HAP and VAP target?
Staphylococcus aureus, Pseudomonas aeruginosa, and other gram-negative bacilli.
When should a pt with HAP/VAP be reassessed and considered for discontinuing or narrowing Abx therapy?
48 to 72 hours after the initiation of therapy
What are the risk factors for MDR pathogens in pt with VAP?
- IV antibiotic use within the previous 90 days
- Septic shock at the time of VAP
- ARDS preceding VAP
- ≥5 days of hospitalization prior to the occurrence of VAP
- Acute renal replacement therapy prior to VAP onset
What is an appropriate empiric therapy for VAP with no MDR risk factors (when local biogram is not resistant)?
Any of:
Piperacillin-tazobactam 4.5 g IV q6h
Cefepime 2 g IV q8h
Levofloxacin 750 mg IV daily
What regimen should pt with MDR risk factors get?
2 agents active against P. aeruginosa & other gram-negative
+
1 agent active against MRSA
Name 5 Abx regimens active against P. aeruginosa & other gram-negative, appropriate for pt with MDR risk factors (6 listed)
Piperacillin-tazobactam 4.5 g IV q6h Cefepime 2 g IV q8h Ceftazidime 2 g IV q8h Imipenem 500 mg IV q6h Meropenem 1 g IV q8h Aztreonam 2 g IV q8h
(This may be more niche than I really need to know?)
Name 3 aminoglycosides
Amikacin 15 to 20 mg/kg IV daily
Gentamicin 5 to 7 mg/kg IV daily
Tobramycin 5 to 7 mg/kg IV daily
Why should aminoglycosides be used cautiously, and discontinued if possible?
- poor lung penetration
- increased risk of nephrotoxicity and ototoxicity
- poorer clinical response rates compared with other antibiotic classes
UpToDate discontinues adjunctive aminoglycosides after 48h if pt is clinically improving
What should you do if you have a pt with VAP and you need to decide on an Abx regimen?
Look it up: will vary with
- local antibiogram
- suspected pathogens (eg legionella)
- time, probably (ie not worth memorizing)
If a pt is clinically improving 48-72h after starting treatment for S. aureus or MDR pathogens, what should you do?
If these pathogens are not grown in culture, d/c agents
What should you do if a pt isn’t improving after being on Abx for 72h?
Evaluate for complications, other sites of infection, and alternate diagnoses
How long do you keep a pt on Abx for HAP or VAP?
7d
Name 3 toxicities of fluoroquinolones
QT interval prolongation, tendinitis and tendon rupture, and neurotoxicity.
What toxicity is seen in polymyxins?
Nephrotoxicity
What toxicity is associated with the combination of vancomycin and pip-tazo?
AKI
What adverse event is seen in pt with renal insufficiency on imipenem and cefepime?
Seizure
What is the goal of combination therapy in HAP and VAP?
Ensure that at least one active agent is administered as soon as possible in patients at risk for multidrug-resistant (MDR) pathogens
(during the empiric treatment phase before the infecting pathogen(s) has been identified and susceptibilities reported)
What variables are associated with increased mortality in VAP and HAP?
- Serious illness at the time of diagnosis (eg, high APACHE score, shock, coma, respiratory failure, ARDS)
- Bacteremia
- Severe underlying comorbid disease
- Infection caused by an organism associated with multidrug resistance
- Multilobar, cavitating, or rapidly progressive infiltrates on lung imaging
- Delay in the institution of effective antimicrobial therapy
What two things are required to produce aspiration pneumonia?
1) Compromise in the usual defenses that protect the lower airways (eg glottic closure, cough reflex, other clearing mechanisms)
2) One of:
- An inoculum deleterious to the lower airways by a direct toxic effect (such as gastric acid)
- stimulation of an inflammatory process from bacterial infection
- obstruction due to uncleared fluid or particulate matter
What risk factors increase risk of aspiration pneumonia specifically? (over 5 listed)
- reduced LOC
- Dysphagia
- Disorders of upper GI tract (esophageal disease, surgery, reflux)
- mechanical disruption of glottic closure: trachostomy, ET intubation, bronchoscopy, endoscopy, NG feeding
- pharyngeal anesthesia
Other misc: protracted vomiting, large-volume tube feedings, feeding gastrostomy, the recumbent position, and drowning
What should be done for pt with observed aspiration?
Immediate tracheal suction to clear fluids and particulate matter that may cause obstruction
This maneuver will not protect the lungs from chemical injury, which occurs instantly
What are the categories/syndromes of aspiration pneumonia?
chemical pneumonitis
bacterial infection
airway obstruction
What are the more modifiable risk factors for CAP?
- Smoking, EtOH, opioid
- crowded living conditions
- “residence in low-income settings”
- environmental toxins
