Diagnosis
How do you define community-acquired pneumonia?
Presence of opacity by radiologic studies associated with clinical findings such as fever, cough and leukocytosis.
What diagnostic tests other than CXR do you order for CAP?
Sputum cultures
Blood cultures
MRSA swab - high negative predictive value for MRSA
Molecular testing
Legionella and Pneumococcal Urine antigens
Viral panel: Covid-19 PCR, RSV, Influenza virus
How many days of antibiotics should be prescribed at discharge (for uncomplicated CAP)?
One
One
AorB
Three
Five
Total of 5 days for resolving CAP (or 3 days after clinical stability)
o Retrospective cohort study of 6481 patients at 43 Michigan hospitals with CAP or HCAP
o 71.8% of the patients received excess antibiotic therapy
o Average duration was 2 extra days of therapy
o 93.2% completed their excess therapy as outpatient
o Excessive therapy was associated with antibiotic-associated adverse events (diarrhea, GI distress, mucosal candidiasis)
Vaughn et al., Ann Int Med, 2019; 171:153-163 doi:10.7326/M18-3640
What are the typical bacterial causes of CAP?
S. pneumoniae
Hemophilus influenzae
Staphylococcus aureus
Group A streptococci
Aerobic gram-negative bacteria (Klebsiella or E. coli)
Microaerophilic bacteria and anaerobes (associated with aspiration)
What if the CXR is negative? What do we order next?
A. CT chest
B Lung UTS
C. Procalcitonin
D. Molecular test
E. PET scan
Lung UTS: sensitivity/specificity is equivalent to CT when appropriate protocols are combined at 0.94%
Competence achieved after 25 reviewed exams.
The next option is a CT chest - almost the Gold standard as per SHM 2024, best used in intermediate probability
What antibiotics should we use?
A. Ceftriaxone and azithromycin
B. Ceftriaxone, azithromycin,and vancomycin
C. Cefepime and vancomycin
D. Cefepime, vancomycin, and an aminoglycoside E. Amikacin, colistin,and telavancin
Ceftriaxone and azithromycin
What antibiotics are recommended (ATS/IDSA guidelines) for empiric treatment in the inpatient setting, with no risk factors for MRSA or P. aeruginosa?
In nonsevere community acquired pneumonia:
• Combination therapy with a β-lactam and a macrolide Or
• Monotherapy with a respiratory fluoroquinolone
If there are contraindications to macrolides or fluoroquinolones: • Combination therapy with a β-lactam and doxycycline
In severe community acquired pneumonia:
• Combination therapy with a β-lactam and a macrolide
Or
• Combination therapy with a β-lactam and respiratory fluoroquinolone
Metlay et al., AJRCCM 2019; 200(7):e45-67
What atypical bacteria are associated with CAP?
Legionella spp
Mycoplasma pneumoniae
Chlamydia psitaci
Coxiella burnetti
What is the Light's criteria?
ANY one of the following is defined as an exudate:
Pleural fluid/serum protein ratio > 0.5
Pleural fluid/serum LDH > 0.6
Pleural fluid LDH > 0.67 the upper limit of normal serum LDH
What about Doxycycline?
Updates on use of doxycycline:
Doxycycline may be protective against Clostridium difficile
• Multicenter, retrospective cohort study of 15,6107 patients with CAP in the U.S.
• 13.1% received ceftriaxone plus doxycycline.
• Patients with previous CDI who received ceftriaxone plus doxycycline had a 17% decreased risk compared to patients who received ceftriaxone plus azithromycin.
Doxycycline is equivalent therapy in mild-to-moderate CAP
• Multicenter, retrospective cohort study of 23,512 patients with mild-to- moderate CAP in Ontario, Canada
• 2.2% received received ceftriaxone plus doxycycline.
• In-hospital mortality and time to discharge were the same as Cft + azithro or a fluoroquinolone
O’Leary et al., Am J Infect Control, 2023, https://doi.org/10.1016/j.ajic.2023.09.007 Bai et al., Chest 2024; 165(1):68-78
Clinical indicators or calculators used to aid in making decision if a patient can be admitted or not in the hospital?
SHM 2024 encourages hospitalists to use the Pneumonia Severity Index and/or CURB-65 in deciding whether to admit a patient to the hospital or not.
1. Pneumonia Severity Index: class III or higher warrants admission
2. CURB-65 (Confusion,BUN/Urea,RR>=30,SBP<=90 or DBP <=60, Age=> 65 yo). Predicts mortality.
What are the limitations of Light's Criteria?
1. Costly and inconvenient: requiring simultaneous pleural fluid and serum specimens
2. High sensitivity and moderate specificity for exudative pleural effusions. 25 or 30% of transudates are incorrectly classified as exudates, e.g. heart failure patients and malignancy
What are the risk factors for Pseudomonas or MRSA?
Risk factors for Pseudomonas or MRSA:
Previous contact with the healthcare system in past 90 days:
Prior hospitalization, especially ICU care
Nursing home resident
Home IV antibiotic therapy
Hemodialysis
Home wound care
Host risk factors:
Immunosuppression Diabetes
Chronic respiratory disease
Other therapies:
Corticosteroids
Gastric acid suppression
Broad-spectrum antibiotic use
Bronchiectasis
CV disease
Poor functional status
Other immunosuppressants
Tube feeding
Niederman and Torres, Eur Resp Review, 2022, https://doi.org/10.1183/16000617.0123-2022
Have you heard of the Pleural fluid-only three-test combination (PFO3)?
Preferred by experts than Light's criteria.(First approach)
Exudate is defined if any one or more of the following are present:
Pleural fluid > 3.0 g/dL
Pleural fluid cholesterol > 55 mg/dL
Pleural fluid LDH > 0.67 times the ULN
Advantages:
1. Obviates use of blood levels (less cost)
2. Similar accuracy as Light's criteria
What else should we add (severe CAP)?
Azithromycin
Hydrocortisone
Prednisolone
Nothing
Sauna and a personal masseuse
Corticosteroids in pneumonia
• Randomized, controlled trial of 800 patients with severe CAP
• Randomized to either hydrocortisone (200 mg/day infusion for 4-7 days, followed by an 8-14 day taper) or placebo
• Significant lower mortality rate at 28 and 90 days (6.2% vs 11.9%)
• Meta-analysis of 15 RCTs and 3367 patients
• 9 trials included patients with severe CAP
• Significant reduction in all-cause mortality and ARDS, most pronounced in severe CAP
• Increase in hyperglycemia, no other difference in adverse events
REMEMBER exclusion criteria:
• nosocomial pneumonia
• Immunocompromise
• uncontrolled psychiatric symptoms • recent GI bleed
• Influenza
• uncontrolled diabetes
What is the role of Procalcitonin?
Meta-analysis of 12 studies (2408 patients), with known CAP etiologies
Sensitivity = 0.55 Specificity = 0.76 AUC = 0.73
When CAN you use procalcitonin?
o No studies comparing biomarkers to clinical signs in prognostication
o No studies demonstrating the benefit of biomarkers vs. clinical signs on antibiotic initiation in pneumonia in hospitalized patients
o There is evidence demonstrating a decrease of antibiotic duration without significant harm – but all studies showed antibiotic reduction to current recommended guidelines
o There are many caveats using procalcitonin in the setting of COVID-19
So:
o Possible use in patients for whom you may be considering a prolonged antibiotic course
o Possible use in antimicrobial stewardship efforts
COCC 2018, 24: 361-369; Eur Resp J 2017, 50: 1700582