Conquer community acquired pneumonia and avoid misdiagnosis with tips from Dr. Robert Centor, Professor Emeritus University of Alabama and newly appointed Chair of Medicine at Kashlak Memorial Hospital. We discuss diagnosis, misdiagnosis, procalcitonin, steroids for severe pneumonia, pneumonia severity index versus CURB-65, and how to determine antibiotic choice and duration. Special thanks to Correspondents Neela Bhajandas (cohost), Justin Berk and Bryan Brown who all contributed several articles, resources, and questions to prep for this show.
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Case from Kashlak Memorial:38 year old male, active smoker with bipolar disorder (on olanzapine 20 mg hs, citalopram 40 mg), obesity (BMI 31), HTN (on lisinopril/HCTZ) presents to the ED with 7 days of progressive cough with scant sputum production, dyspnea on exertion, and wheezing. The ED called me to evaluate him for admission.
“…being called from the emergency department for the diagnosis of community acquired pneumonia is a chance for us to think.”…”let’s first assume that it’s NOT that, and then try to convince ourselves that it is pneumonia”. -Dr Centor
Rules for early antibiotic administration prompted attempts by the ED to diagnose pneumonia with higher sensitivity. This led to lower specificity, increased number of false positives and antibiotic (abx) overuse. -Dr Centor
new or increasing infiltrate by chest x ray (CXR) or chest CT
plus, temp >38.0°C or <35.1°C or a WBC > 10/μL or < 4.5/μL, or bands > 15%;
plus, 2 of: cough, dyspnea, pleuritic chest pain, tachypnea w/RR > 30/min, hypoxia <90% or PaO2 < 60 mmHg, auscultatory findings of pneumonia, including: rales, dullness of percussion, bronchial breath sounds, or egophony; or newly required mechanical ventilation by either intubation or noninvasive ventilation.
Community acquired pneumonia (CAP) definition: Pneumonia caused by any of various organisms that does not meet diagnostic criteria for HAP or VAP (see below).
Hospital acquired pneumonia (HAP) definition: occurs 48 hours or more after hospital admission and wasn’t incubating at the time of admission. Ventilator associated pneumonia (VAP) develops more than 48 to 72 hours after endotracheal intubation (IDSA HAP and VAP g/l 2016, and UpToDate.com).
Healthcare associated pneumonia (HCAP) definition: Don’t use this term anymore! Treat these patients as CAP and assess/treat if multidrug resistance risk factors present (see below for MRSA and Pseudomonas).
Assess MRSA risk factors and treat for MRSA if: GPCs in clusters on sputum gram stain, ESRD, IVDU, recent influenza, necrotizing or cavitary pneumonia (IDSA CAP g/l 2007)
Assess Pseudomonas risk factors and treat if: GNR on sputum gram stain, COPD with frequent exposure to steroids/antibiotics, structural lung disease (e.g. bronchiectasis), “prior abx exposure”, alcoholism [IDSA CAP g/l 2007].
Assess Drug resistant Streptococcus pneumoniae (DRSP) risk factors and treat if: Local Strep resistance to macrolide >25%; age >65; comorbidities; alcoholism; exposure to kids in daycare; Beta lactam, fluoroquinolone (FQ), or macrolide abx use in past 3-6 months. (UptoDate)
“Comorbidities” per [IDSA CAP g/l 2007]: Chronic heart, lung, liver, renal disease, diabetes, cancer, alcoholism, asplenia, immunosuppression, abx exposure in past 3 mo.
Pneumonia may “blossom” on repeat CXR after initial negative study if initial BUN elevated or if higher fluid volume administered in first 48 hours (RB Hash J Fam Pract 2000)
Illness script: Expected patient presentation (history, labs, exam, signs/symptoms) for a given problem e.g. pneumonia.
Problem representation: A brief summary of what is wrong with the patient.
Diagnosis/Misdiagnosis: A patient’s “illness script” must match their “problem representation”. If not, then clinician must consider other diagnoses through analytical thinking and differential diagnosis. -Dr Robert Centor (see this article)
Pneumonia scoring systems: Useful to estimate mortality risk. Low risk patients can be sent home. High risk patients need admission. Plan MUST take into account the patient’s social support and ability to comply with treatment.
Pneumonia severity index (PSI):Calculator found here. Outpatient care for scores I-II. Score of III is borderline. Inpatient care for scores IV-V (IDSA CAP g/l 2007). Calculation requires blood gas, basic metabolic panel, blood count, oxygen sat, CXR. Less cumbersome to calculate using smartphone. Dr Centor recommends PSI over CURB-65.
CURB-65: Confusion, uremia (BUN >20), RR ≥30, Systolic BP <90, Diastolic BP ≤60, Age >65. Inpatient care if score ≥2. Severe pneumonia if score 3-5 (IDSA CAP g/l 2007).
Additional testing and labs:Consider checking blood cultures, sputum cultures (Dr Centor is not a fan), legionella urinary Ag, pneumococcal urinary Ag. See Table 3 in IDSA pocket card for details.
Procalcitonin (PCT): A calcitonin-related gene product. PCT production increased w/bacterial infections and decreased w/viral infection. PCT falls rapidly during recovery/tx of bacterial infection. Consider starting abx if >0.25 mcg/L in outpatients or ED, and >0.5 mcg/L in ICU. Cut-offs for starting, and stopping abx differ by study and assay used. Only helpful if rapid results available (i.e. within hours). May decrease 30-day mortality, abx exposure, abx side effects (Scheutz P. Lancet Infectious Diseases 2017). Outpatient management with PCT is cost-effective. Overall, use of PCT overall still controversial among ID docs.
Antibiotic choice outpatient without comorbidities: Macrolide or doxycycline. Modify as needed if risk factors for MRSA, pseudomonas, DRSP (see above).
Antibiotic choice outpatient with comorbidities: Monotherapy with respiratory FQ, or Beta lactam (high dose amoxicillin or high dose amoxicillin-clavulanic acid or 2nd/3rd gen. cephalosporin) plus macrolide (or doxycycline). Modify as needed if risk factors for MRSA, pseudomonas, DRSP (see above).
Antibiotic duration: Should see improvement within first 48-72 hours on tx. Otherwise, one must question the diagnosis of pneumonia. It’s okay to stop abx at 5 days if markers of clinically instability are absent (e.g. no oxygen requirement above patient’s baseline, afebrile for 48-72 hours, HR <100, RR <24, SBP >90) (IDSA CAP g/l 2007).
QTc prolongation: “The more the merrier”. Thus, using a higher number of QTc prolonging agents increases the risk for torsades de pointe. Be careful!
Corticosteroids in severe pneumonia: Treats a hypothesized “critical illness related corticosteroid insufficiency” aka relative adrenal insufficiency. Not currently recommended for routine use in pneumonia, but may be considered if severe.
Evidence for steroids in severe pneumonia: Meta-analysis by Siemieniuk et al Annals of IM 2015 showed decreased length of hospital stay, need for mechanical ventilation, ARDS, and time to clinical stability, especially in severe pneumonia. Meta-analysis by J. Bi et al PLoS One 2016 found decreased relative risk all-cause mortality, ARDS, and need for mechanical ventilation in patients with severe CAP, but studies were small with wide confidence intervals.
Goal: Listeners will utilize an evidence based approach to prognosis, diagnosis, and management of community acquired pneumonia Learning objectives: After listening to this episode listeners will…
Define community acquired pneumonia
Recall why pneumonia is commonly misdiagnosed
Utilize illness scripts and problem representation to evaluate diagnostic accuracy
Utilize available risk scores to stratify patients with CAP and determine appropriate level of care
Evaluate efficacy of steroids for severe CAP
Utilize procalcitonin to guide antimicrobial use and duration
Choose the appropriate antibiotics based on risk factors and setting
Determine appropriate antibiotic duration
Disclosures: Dr Centor, The Curbsiders, and Dr Bhajandas report no relevant financial disclosures.
02:38 Brief bio for Dr Centor
04:22 Picks of the week with Dr Centor
11:27 Clinical case of suspected pneumonia
12:30 Brief history of community acquired pneumonia
14:40 Misdiagnosis rates are high
16:18 Defining diagnostic criteria for pneumonia
18:50 Chest x rays and pneumonia
22:18 Illness scripts teaching about pneumonia
23:41 Ubiquitous misunderstanding of pneumonia definition
25:26 History and physical exam tips from Dr Centor
27:19 Further testing for pneumonia, PSI, CURB-65
32:50 Procalcitonin discussed
38:10 Antibiotic choice discussed with Dr Bhajandas
41:15 Safety considerations for various antibiotics
43:38 Use of high dose amoxicillin
44:45 Dr Centor’s antibiotic preferences, and some thoughts on blood and sputum cultures
46:55 Dangers of fluoroquinolones
48:25 Antibiotic duration
51:40 HCAP is no longer a thing and how to assess risk for drug resistant organisms