Pneumonia: Diagnosis and Treatment Guide

1. Symptoms:

• Sudden high fever, sweating or chills

• Cough with rusty or green, purulent sputum

• Pleuritic chest pain, difficulty breathing

• Body aches, lung rales

2. Diagnosis:

• Blood tests: Increased WBC, increased NEU; Increased erythrocyte sedimentation rate

• Biochemical tests: Increased CRP, Increased procalcitonin (>0.5 ng/L)

• Blood gas analysis: Decreased oxygen saturation

• Imaging:

• Chest X-ray (gold standard)

• CT scan

• Microbiology tests: Diagnosis of pneumonia when the number of bacteria in sputum and blood samples (2 blood cultures) reaches a certain threshold:

• Endotracheal aspirate (EA): >10^6 CFU/ml

• Sputum:

• 10^5 CFU/ml (S. pneumoniae)

• >10^6 CFU/ml (H. influenzae) or (M. catarrhalis)

• Bronchoalveolar lavage (BAL): >10^4 CFU/ml

• Protected specimen brush (PSB): 10^3 CFU/ml

• PCR testing of sputum, respiratory secretions: Microbiology test

• Criteria for microbiology testing:

• Outpatient: Not needed

• Inpatient:

• Severe CAP (ICU admission, intubation)

• Empirical treatment targeting MRSA or P. aeruginosa

• Previous MRSA or P. aeruginosa infection

• Hospitalization and intravenous antibiotic use within the past 90 days

• Patients without travel to epidemic areas: Routine testing for Legionella and S. pneumoniae antigens in urine is not required.

3. Pneumonia classification:

• According to imaging:

• Lobar pneumonia

• Bronchopneumonia

• Interstitial pneumonia

• Necrotizing pneumonia

• According to practice:

• Community-acquired pneumonia (CAP)

• Hospital-acquired pneumonia (HAP)

• Healthcare-associated pneumonia (HCAP)

• Aspiration pneumonia

4. Community-acquired pneumonia (CAP):

• Epidemiology: Prevalent in children under 5 years of age and individuals over 65. Average mortality rate of 5-10%. The disease is at risk of severe progression and death in elderly individuals or those with multiple underlying chronic illnesses.

• Causative agents:

• Bacteria:

• Streptococcus pneumoniae

• Staphylococcus aureus

• Haemophilus influenzae

• Moraxella catarrhalis

• Legionella pneumophila

• Chlamydia pneumoniae

• Mycoplasma pneumoniae

• Gram-negative bacilli (Pseudomonas aeruginosae, E. coli …)

• Viruses:

• Influenza A virus

• Influenza B virus

• SARS-coronavirus…

• Classification by severity:

• Mild, outpatient treatment: Atypical bacteria, Strep

• Moderate, inpatient treatment (non-ICU): Strep, atypical bacteria, Gram-negative intestinal bacteria

• Severe, ICU treatment: Strep, Gram-negative intestinal bacteria, S. aureus, Pseudomonas

• CURB-65 score: Assessing CAP severity

• C: Confusion, disorientation

• U: Blood urea > 7 mmol/L

• R: Respiratory rate > 30 breaths/minute

• B: Blood pressure < 90/60 mmHg

• 65: Age > 65

• 0-1 point: Outpatient treatment

• 2 points: Outpatient treatment with monitoring or consideration of short-term inpatient treatment

• 3-5 points: Hospitalization required

• 4-5 points: ICU admission indicated

• ICU admission criteria:

• At least 1 major criterion or at least 3 minor criteria.

• Major criteria:

• Respiratory failure requiring mechanical ventilation

• Septic shock requiring vasopressor medication

• Minor criteria:

• Respiratory rate > 30 breaths/minute

• PaO2/ FiO2< 250

• Involvement of multiple lung lobes on chest X-ray

• Confusion, disorientation

• Blood urea (BUN > 20 mg/dL)

• White blood cell count < 4000/ mm3

• Platelet count (<100.000/ mm3)

• Hypothermia (< 36oC)

• Hypotension requiring aggressive fluid resuscitation.

5. Treatment principles (CAP & HAP):

• Eradicate the causative bacteria using appropriate antibiotics.

• Treat clinical symptoms.

• Reduce mortality rate, decrease disease complications, and minimize drug toxicity to organs.

• Inpatients/hospitalized patients should be treated empirically with antibiotics shortly after diagnosis.

• Optimize antibiotic use according to PK/PD, antibiotic penetration into the site of infection, and adjust according to renal function to reduce antibiotic resistance.

• Microbiological samples should be collected before antibiotic administration.

6. Outpatient treatment:

• CURB-65 (0-1 point):

• Patients < 65 years of age:

• No co-morbidities:

• Amoxicillin 1g x 3 times/day

• Doxycycline 100mg x 2 times/day

• Azithromycin (oral) 500mg on the first day, then 250mg on subsequent days

• Clarithromycin (oral) 500mg x 2 times/day or slow-release 1g x 1 time/day

• Patients > 65 years of age:

• Co-morbidities: Amoxicillin/clavulanate 500 mg/125 mg x 3 times/day

• Immunosuppression: Amoxicillin/clavulanate 875 mg/125 mg x 2 times/day or 2,000 mg/125 mg x 2 times/day

• Antibiotic use 3 months prior: Cefpodoxime 200 mg x 2 times/day

• Risk of drug-resistant S.pneumoniae: Cefuroxime 500 mg x 2 times/day

• AND:

• Azithromycin 500 mg on the first day, then 250 mg/day

• Clarithromycin 500mg x 2 times/day or slow-release 1g x 1 time/day

• Doxycyclin 100 mg x 2 times/day

• OR MONOTHERAPY:

• Levofloxacin 750 mg/day

• Moxifloxacin 400 mg/day

• Gemifloxacin 320 mg/day

• CURB-65 (2 points):

• No risk of MRSA or P. aeruginosa infection:

• Beta-lactam +/- betalactamase inhibitor:

• Ampicillin + sulbactam 1.5-3 g q6h

• Amoxicillin/clavulanate 1.2 g q8h

• Cefotaxime 1-2 g q8h

• Ceftriaxone 1-2 g/day

• Ceftaroline 600 mg q12 h

• Ertapenem 1g q24h

• PLUS:

• Macrolide: Azithromycin 500 mg/day, Clarithromycin 500mg x 2 times/day

• Or quinolone: Levofloxacin 750 mg/day, Moxifloxacin 400 mg/day

• Macrolide or quinolone allergy: Doxycyclin 100 mg x 2 times/day

• OR monotherapy respiratory fluoroquinolone (sterile site): Levofloxacin 750 mg/day, Moxifloxacin 400 mg/day

7. Inpatient treatment:

• CURB-65 (3-5 points):

• Broad-spectrum beta-lactam +/- betalactamase inhibitor or carbapenem:

• Piperacillin/tazobactam 4.5 g IV q6h

• Cefotaxime 1-2 g q8h

• Ceftriaxone 1-2 g/day

• Ceftaroline 600 mg q12 h

• Cefepim 2g q8h

• Ertapenem 1g q24h

• PLUS:

• Macrolide: Azithromycin 500 mg/day, Clarithromycin 500mg x 2 times/day

• Or quinolone: Levofloxacin 750 mg/day, Moxifloxacin 400 mg/day

• CURB-65 (3-5 points) if suspected atypical bacterial infection:

• Suspected Pseudomonas infection:

• Anti-Pseudomonas β-lactam (piperacillin/tazobactam, ceftazidim, cefepime, cefoperazon, imipenem, meropenem, doripenem)

• PLUS:

• Ciprofloxacin or levofloxacin

• 1 aminoglycoside and azithromycin/clarithromycin

• Suspected MRSA infection:

• Broad-spectrum beta-lactam +/- betalactamase inhibitor or carbapenem

• PLUS:

• Vancomycin or Teicoplanin, or Linezolid (preferred over patients with impaired renal function or those using nephrotoxic medications) when MIC > 1

8. Treatment monitoring:

• Vital signs

• If the patient does not respond, exclude other causes, consider co-infection, evaluate the appropriateness of the antibiotic used, repeat microbiological tests and antibiogram, look for TB, fungi…

• Continue oral antibiotics after discharge for patients with pneumonia complications due to S. pneumoniae, sepsis, S. aureus, gram-negative bacteria, legionella, pneumonia complications from endocarditis, lung abscess, empyema

9. Vaccination:

• Influenza vaccination: Annually in individuals > 50 years of age, indicated for individuals with chronic cardiopulmonary diseases, diabetes, severe renal failure, immunosuppression.

• Pneumococcal vaccination:

• Every 5 years when the first dose is given < 65 years of age

• If the first dose is given > 65 years of age, then no booster is needed, indicated for individuals with chronic cardiopulmonary diseases, diabetes, alcoholism, chronic liver disease, cerebrospinal fluid leaks, splenectomy, immunosuppression.

10. Treatment duration:

• CAP:

• Until the patient reaches a stable state, no fever for 48-72 hours, no unstable clinical factors.

• If outpatient treatment, not less than 5 days.

• HAP:

• Antibiotic discontinuation should only occur when clinical response is achieved for at least 72 hours.

• Typically 14-21 days.

• 7 days: In patients without clinical symptoms and the cause is not Pseudomonas.

11. Comparison of CAP and HAP:

• HAP has a higher mortality rate than CAP, possibly due to age, exposure to infection sources…

• HAP is less likely to have typical symptoms (fever, chills…) but occurs along with confusion and altered consciousness.

12. Risk factors for exposure to multi-drug resistant bacteria:

• Hospitalization for multiple days in a healthcare facility within the past 90 days.

• Exposure to antibiotics, chemotherapy, wound care within the past 30 days.

• Residence in a nursing home or long-term care facility.

• Hemodialysis at a hospital/clinic.

• Nursing care (infusion, wound care…)

• Contact with family members/personnel infected with multi-drug resistant bacteria.

13. Hospital-acquired pneumonia (HAP):

• Pneumonia acquired after hospitalization > 48 hours.

• Includes early-onset pneumonia (<5 days after hospitalization) and late-onset pneumonia (>5 days after hospitalization).

• Characterized by an increased risk of exposure to multi-drug resistant bacteria.

14. Causative agents of HAP:

• Gram-negative bacilli:

• E.coli

• Klebsiella pneumoniae

• Enterobacter spp.

• Pseudomonas aeruginosa (late)

• Acinetobacter spp. (late)

• Haemophillus influenzae (early)

• Moraxella catarrhalis

• Gram-positive cocci:

• S.aureus: MSSA (early) and MRSA (late)

• Streptococcus pneumoniae (early)

15. High risk factors for exposure to multi-drug resistant HAP bacteria:

• Late-onset hospital-acquired pneumonia.

• Intravenous antibiotic use within the past 90 days.

• Recent hospitalization (> 5 days).

• Underlying conditions (Immunodeficiency, Respiratory conditions such as cystic fibrosis, bronchiectasis, COPD, diabetes…)

• Frequent use of glucocorticoids.

• Alcoholism.

• Prior infection with multi-drug resistant bacteria.

• Epidemiology with a high prevalence of MRSA, gram-negative bacilli dominance.

16. Ventilator-associated pneumonia (VAP):

• A form of hospital-acquired pneumonia.

• Pneumonia develops after endotracheal intubation for at least 48 hours.

17. Diagnosis of pneumonia causative agents based on experience:

• Need to consider:

• Pneumonia classification: HAP (early/late onset), CAP, HCAP, VAP

• Severity: Outpatient treatment, inpatient treatment in respiratory ward, inpatient treatment in ICU

• Patient background: Age, lifestyle habits, co-morbidities (pulmonary/systemic)

18. Pneumonia prevention measures:

• Influenza and pneumococcal vaccination.

• Environmental hygiene.

• Hand washing, wearing masks when sick.

• Smoking cessation.

• Treatment of underlying conditions that damage lung structure/reduce immunity.

19. Principles of antibiotic use in HAP:

• Early antibiotic use, within 24 hours or earlier after diagnosis.

• Selection of antibiotics different from those previously administered to the patient.

20. HAP treatment:

• Early-onset HAP AND no suspicion of multi-drug resistant bacteria infection:

• Ampicillin + sulbactam 1.5-3 g q6h

• Amoxicillin/clavulanate 1.2 g q8h

• Ertapenem 1g q24h

• Ceftriaxone 1-2g q24h or Cefotaxime 1-2g q6h

• Levofloxacin 750mg IV q24h or Ciprofloxacin 400mg IV q8h-12h or Moxifloxacin 400mg q24h (if atypical bacteria are suspected)

• HAP with risk of multi-drug resistant bacteria infection (No high mortality risk + No MRSA infection risk):

• Piperacillin-tazobactam 4.5 g IV q6h

• Cefepime 2 g IV q8h

• Levofloxacin 750 mg IV q24

• Imipenem/cilastatin 500 mg IV q6h

• Meropenem d 1 g IV q8h

• HAP with risk of multi-drug resistant bacteria infection (No high mortality risk + MRSA infection risk):

• Piperacillin-tazobactam 4.5 g IV q6h

• Cefepime 2 g IV q8h

• Levofloxacin 750 mg IV q24/Ciprofloxacin 400mg q8h

• Imipenem/cilastatin 500 mg IV q6h

• Meropenem 1 g IV q8h

• Aztreonam 2g q8g

• PLUS:

• Vancomycin 15 mg/kg IV q8-12h (monitor antibiotic levels during treatment)

• Linezolid 600 mg IV q12h

• Teicoplanin: Initial dose: 400mg q12h x 3, Maintenance: 400mg (6mg/kg) q24h.

• HAP with risk of multi-drug resistant bacteria infection (High mortality risk + IV antibiotic use within the past 90 days):

• Combine 2 of the following antibiotics, avoid using 2 beta-lactams:

• Piperacillin-tazobactam 4.5 g IV q6h

• Cefepime 2 g IV q8h/ ceftazidime 2g IV q8h

• Imipenem_cilastatin 500 mg IV q6h / Meropenem d 1 g IV q8h

• Levofloxacin 750 mg IV q24/Ciprofloxacin 400mg q8h

• Amikacin 15-20 mg/kg IV q24h/ Gentamicin 5-7 mg/kg IV q24h/ Tobramycin 5-7mg/kg IV q24h

• PLUS:

• Vancomycin 15 mg/kg IV q8-12h (monitor antibiotic levels during treatment)

• Linezolid 600 mg IV q12h

• Teicoplanin: Initial dose: 400mg q12h x 3, Maintenance: 400mg (6mg/kg) q24h.

21. Side effects of some antibiotics:

• Vancomycin:

• Nephrotoxicity (especially when combined with piperacillin/tazobactam, aminoglycosides)

• Hearing loss (especially when combined with aminoglycosides)

• Rapid infusion causes “red man” syndrome

• Leukopenia (rare) when used for 2-3 weeks

• Penicillin:

• Allergy (urticaria, angioedema, anaphylactic shock)

• Nausea, vomiting, and diarrhea

• Drug fever, rash, interstitial nephritis, neurotoxicity, and hematologic abnormalities

• Cephalosporin:

• Allergy (rare), cross-allergy with penicillin is low (5%)

• Leukopenia, thrombocytosis, hemolysis, diarrhea, and elevated liver enzymes (rare)

• Decreased prothrombin time and disulfiram-like reaction with alcohol (cefotetan and cefoperazon)

• Cetriaxone: High doses can cause bile duct obstruction (excreted through bile)

• Carbapenem:

• Nausea, vomiting, diarrhea, rash, and drug fever

• Seizures (high risk in patients with CNS disorders and renal failure)

• Fluoroquinolone:

• Tendinitis, Achilles tendon rupture (watch out for patients complaining of leg pain, swelling without mechanical cause)

• Prolonged QT interval

• TDP in the CNS such as headache, dizziness

• Avoid use in patients with a history of myasthenia gravis (can cause relapse of myasthenia gravis)

• TDP in the gastrointestinal tract is the most common

• Clostridium difficile-associated diarrhea

• Aminoglycoside:

• Nephrotoxicity, recovery after discontinuation

• Ototoxicity: Hearing loss (irreversible) and vestibular toxicity (causes loss of balance)

• Linezolid:

• Diarrhea, nausea, vomiting

• Headache

• Anemia, thrombocytopenia, leukopenia

• Clindamycin:

• Clostridium difficle-associated pseudomembranous colitis

• Diarrhea, rash

Note: This information is for reference only and cannot replace medical advice. Please consult a doctor for timely diagnosis and treatment.