Pneumonia – AFP 2011

Community-acquired pneumonia (CAP)
  • Pulmonary parenchyma infection
  • Not hospitalized within 14 days of onset OR hospitalized <4days prior to onset

Typical Pneumonia: S. Pneumoniae, Moraxella catarrhalis, Haemophilus influenzae, Staph aureus, GAS
Atypical pneumonia: mycoplasma pneumoniae, chlamydia pneumoniae, legionella, respiratory viruses (influenza virus / adenovirus)
HIV associated: Pneumoncystis jiroveci, Cryptococcus, CMS/HSV/TB
EtOH: Klebsiella, enteric, GNB, S aureus, TB, oral anerobes
Aspiration: Oral anerobes (Bacteroides), gastric content – chemical pneumonitis


Hx:
  • F/C, pleuritic chest pain, dyspnea, new cough / sputum production or chronic cough with change in color of sputum
  • Hemoptysis (necrotizing pneumonia / TB / Gram -)
  • Constitutional symptoms: Wt loss, night sweats
  • Occupation
  • Animal exposure
  • Sexual Hx
  • Recent travel Hx (2 week)
O/E:
  • Temp > 37.8
  • Tachycardia (LR+ = 2.1)
  • Tachypnea >25/min (LR+ 3.5)
  • Consolidation signs
    • Dullness to percussion,
    • Asymmetric breath sounds / deminished a/e , pleural rubs, egophony, ↑ tactile fremitus (uncommon LR+ = 8)
    • Pleural rub
    • localized crackles
    • Egophnoy
  • Pulse oximetry – in all pt with ?CAP
CXR – performed in pt with clinically suspected CAP
  • An infiltrate on lung imaging is required for dx of CAP
  • Lobar consolidation, cavitation, and pleural effusions suggest a bacterial etiology.
  • Diffuse parenchymal involvement – Legionella or viral pneumonia
  • Necrotizing / cavitary pneumonia may be caused by MRSA
  • Pleural effusion >5cm on Lateral CXR should be drained by thoracentesis
Dx
  1. ≥ 2 of the following symptoms:
    • fever, rigors,
    • new cough with or without sputum production or chronic cough with change in color of sputum,
    • pleuritic chest pain,
    • shortness of breath
  2. AND  – Auscultatory findings consistent with pneumonia: localized crackles, bronchial breath sounds
  3. AND  –  The presence of a new opacity on chest X-ray
  4. Less likely if sore throat / rhinorrhea, asthma
Sputum Cx obtained before the initiation of Abx in inpatients
  • – sputum Cx from a good sample ( + neutrophils, <25 epitheila) = gram – bacillia / staph aureus are absent
Urine antigen test for Legionella
  • + on the first day and for several weeks
  • – test doesn’t r/o infection

1  In a patient who presents without the classic respiratory signs and symptoms (e.g., deterioration, delirium, abdominal pain), include pneumonia in the differential diagnosis.

Elderly often present atypically: altered LOC is sometimes the only sign

Community-acquired pneumonia is diagnosed by clinical features (moderately accurate for dx):
  1. Fever LR+ = 4.5
  2. Pleuritic chest pain
  3. a cough producing mucopurulent sputum
  4. ↑ in COPD & HIV
Legionella: Often present with weakness & ↓ function & mentation in older pt
  1. High fever (40oC)
  2. Male
  3. multilobar
  4. GI & neurologic abnormalities
  5. Associated with stays at hotels and on cruise ships
DDX:

Influenza – suggested on the basis of typical symptoms during peak influenza season

  • F/C/myalgia, arthralgias, H/A, fatigue, cough, dyspnea, pharyngitis
  • Rapid antigen testing or direct fluorescent ab for influenza can help with ?antiviral Tx
  • C/I: viral PNA, secondary bacterial PNA, OM, sinusitis, rhabdomyolysis, myositis, encephalitis, meningitis, transverse meylitis, GBS
Risk Factors
  • Elderly
  • Recent Abx (<3mo)
  • Hospitalization (<3mo)
  • Impaired lung defenses
    • Poor cough/gag reflex
    • Impaired mucocilliary transport: smoking, cystic fibrosis, asthma, COPD
    • Immunosuppression: steroids, chemotherapy, AIDS/HIV, DM, EtOH, CRF, ESRD, transplant, lung cancer, chronic steroids, CHF, malnutrition
  • Increased risk of aspiration
    • Impaired swallowing mechanism: impaired consciousness, neurologic illness causing dysphagia, mechanical obstruction

2  In a patient with signs and symptoms of pneumonia, do not rule out the diagnosis on the basis of a normal chest X-ray film (e.g., consider dehydration, neutropenia, human immunodeficiency virus [HIV] infection).

Chest radiography should be performed in:
  • Any patient with at least one of the following abnormal vital signs:
    • Temperature > 100° F (37.8° C)
    • Heart rate > 100 beats per minute
    • Respiratory rate > 20 breaths per minute
  • Any patient with at least two of the following clinical findings:
    • Decreased breath sounds
    • Crackles (rales)
    • Absence of asthma

3  In a patient with a diagnosis of pneumonia, assess the risks for unusual pathogens (e.g., a history of tuberculosis, exposure to birds, travel, HIV infection, aspiration). Evaluation for specific pathogens that would alter standard empiric therapy should be performed when the presence of such pathogens is suspected on the basis of clinical and epidemiologic clues; this testing usually is not required in outpatients.

 

4  In patients with pre-existing medical problems (e.g., asthma, diabetes, congestive heart failure) and a new diagnosis of pneumonia:
a)  Treat both problems concurrently (e.g., with prednisone plus antibiotics).
b)  Adjust the treatment plan for pneumonia, taking into account the concomitant medical problems (e.g., be aware of any drug interactions, such as that between warfarin [Coumadin] and antibiotics).


5  Identify patients, through history-taking, physical examination, and testing, who are at high risk for a complicated course of pneumonia and would benefit from hospitalization, even though clinically they may appear stable.

Mortality and severity prediction scores should be used to determine inpatient versus outpatient care for patients with CAP.

CURB-65 Mortality Prediction Tool for Patients with CAP

  1. Confusion
  2. Uremia – BUN >20/dl (7.14mmol/L)
  3. RR≥ 30/min
  4. BP <90/60
  5. Age ≥ 65
  • 0-1: Tx as outpatient (30-day mortality = 0.7-2.1%)
  • 2: Treat as inpatient (9.2 %)
  • ≥ 3: Tx in ICU (15-40%)

Criteria for Severe CAP

  • Major criteria: ICU adm
    • Invasive mechanical ventilation
    • Septic shock with need for vasopressors
  • Minor criteria: ≥ 1 criteria indicate increased risk of death, and admission to an intensive care unit may be appropriate.
    • Blood urea nitrogen level = 20 mg per dL (7.14 mmol per L)
    • Confusion/disorientation
    • Hypotension requiring aggressive fluid resuscitation
    • Hypothermia (core temperature < 96.8° F [36° C])
    • Leukopenia (white blood cell count < 4,000 per mm3 [4.00 × 109 per L]), Thrombocytopenia (platelet count < 100 × 103 per mm3 [100 × 109 per L])
    • Multilobar infiltrates
    • PaO2/FiO2 ratio ≤ 250 or RR ≥ 30 breaths per minute

6  In the patient with pneumonia and early signs of respiratory distress, assess, and reassess periodically, the need for respiratory support (bilevel positive airway pressure, continuous positive airway pressure, intubation) (i.e., look for the need before decompensation occurs).

SMART-COP Score to Predict Need for IRVS (intensive respiratory / vasopressor support) in Patients with CAP

  • Systolic BP <90 = 2 points
  • Multilobar involvement on CXR = 1
  • Albumin <3.5g/dL (35g/L) = 1
  • RR ≥25 (≤ 50yo) or RR ≥ 30 (>50yo) = 1
  • Tachycardia (≥ 125 bpm) = 1
  • Confusion (new onset) = 1
  • O2 Sat ≤ 93% (≤ 50yo) or O2 Sat ≤ (>50yo) = 2
  • Arterial pH <7.35 = 2

0-2 = low, 3-4 = moderate, 5-6 = high, >6 = very high


7  For a patient with a confirmed diagnosis of pneumonia, make rational antibiotic choices (e.g., outpatient + healthy = first-line antibiotics; avoid the routine use of “big guns”).

Empiric Therapy for CAP – should respond in 72 hrs (d/c if afebrile x 48-72hr)

  1. Previously healthy outpatients; no antibiotic use in past three months =
    • Macrolide (both adult & peds): clarithromycin 500mg bid x 7-14 days or doxycycline 100mg bid x 1 then 100mg daily x 7-14 d
  2. Outpatients with comorbidities* or antibiotic use in past three months (use Abx from a diff class)=
    • Respiratory fluoroquinolone (Levofloxacin 750mg po daily x 5 d, moxifloxacin 400mg po daily x 5 days) or
    • b-lactam (high dose amoxicillin, amoxicillin/clavulanate) + macrolide
  3. In-pt (non-ICU) =
    • respiratory fluoroquinolone or
    • beta-lactam + macrolide (Ceftriaxone + azithro)
  4. ICU = All patients with CAP who are admitted to the intensive care unit should be treated with dual therapy.
    • b-lactam (ceftriaxone / cefotaxime ) + azithromycin or a respiratory fluoroquinolone
  5. Risk factors for pseudomonas:
    • b-lactam (Piptazo / meropenem) + ciprofloxacin or levofloxacin
  6. Risk factors for MRSA =
    • Vancomycin or linezolid
  7. Influenza virus =
    • Tamiflu or Zanamivir

8  In a patient who is receiving treatment for pneumonia and is not responding
a)  Revise the diagnosis (e.g., identify other or contributing causes, such as cancer, chronic obstructive pulmonary disease, or bronchospasm), consider atypical pathogens (e.g., Pneumocystis carinii,TB, and diagnose complications (e.g., empyema, pneumothorax).
b)  Modify the therapy appropriately (e.g., change antibiotics).

Management of Unresponsive CAP

Delayed response to therapy with no improvement after 72 hours, consider:
  • Resistant microorganism or uncovered pathogen
  • Parapneumonic effusion or empyema
  • Nosocomial superinfection
  • Noninfectious condition, such as
    • pulmonary embolism,
    • drug fever,
    • bronchiolitis obliterans,
    • organizing pneumonia,
    • congestive heart failure,
    • vasculitis
    • lung Cancer
Clinical deterioration or continued progression of illness, consider:
  • Severity of illness at presentation
  • Metastatic infection, such as
    • empyema,
    • endocarditis,
    • meningitis,
    • arthritis
  • Inaccurate diagnosis, such as acute respiratory distress syndrome, aspiration, lung cancer
  • Exacerbation of comorbid illness or coexisting noninfectious disease, such as
    • renal failure,
    • acute myocardial infarction,
    • pulmonary embolism

9  Identify patients (e.g., the elderly, nursing home residents, debilitated patients) who would benefit from immunization or other treatments (e.g., flu vaccine, Pneumovax, ribavarine) to reduce the incidence of pneumonia.

Prevention of CAP
  1. universal influenza vaccination and pneumococcal vaccination for patients at high risk of pneumococcal disease.
  2. Smoking cessation, avoid environmental tobacco smoke
  3. Limit the spread of viral infection thru handwashing
  4. Rehabilitation and nutritional programs

10  In patients with a diagnosis of pneumonia, ensure appropriate follow-up care (e.g., patient education, repeat chest X-ray examination, instructions to return if the condition worsens).

Repeat CXR in 6 weeks if
  1. extensive / necrotizing pneumonia
  2. smoker, alcoholism, COPD
  3. >5% wt loss in past month,
  4. >40yo

11  In patients with a confirmed diagnosis of pneumonia, arrange contact tracing when appropriate (e.g., in those with TB, nursing home residents, those with legionnaires’ disease).


References:
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Posted in 74 Pneumonia, 99 Priority Topics, FM 99 priority topics, Resp

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