What is Pneumonia? - NEET PG Medicine

Pneumonia is a common respiratory illness and a leading cause of morbidity and mortality worldwide, especially in young children and elderly individuals. It is a common presentation in clinical practice, and medical professionals need to be familiar with its management, including the use of antibiotics, and supportive care.

Read this blog for a quick overview of this important medicine topic for NEET PG exam Preparation.

Overview

• Commonest cause for community acquired pneumonia is Pneumococcus
• Pneumonia in AIDS +ive patient, low CD4 count of <200 cells / cu.mm 
• Opportunistic infection in AIDS +ive patient is Pneumocystis jirovecii 
• Case 1: AIDS positive truck driver with pneumonia and low CD4 count. He is having bronchial breathing and lobar consolidation
  • Lobar consolidation and bronchial breathing are absent in pneumocystis jirovecii,
  • If bronchial breathing and Lobar consolidation are given in question, the answer is Pneumococcus. Because the leading cause of Pneumonia in AIDS positive patients is Pneumococcus.
  • Low CD4 count is s/o pneumocystis jirovecii but not confirmatory.
  • Conformation of Pneumocystis jiroveci is done by Bronchoalveolar Lavage stained with gomori methenamine silver stain and black cysts of Pneumocystis jiroveci are seen.
  • The word pneumocystis means the cysts causing pneumatocele in Lungs.
• Below X-ray shows Lobar consolidation in Left upper lobe.

• Below X-ray shows Lobar consolidation in the right middle zone.

Also Read: Myocardial Infarction - Neet PG Medicine

Pneumocystis jirovecii 

• Pneumocystis jirovecii causes interstitial pneumonia.
• Chest is clear initially, later develops diffuse rales
• Chest X-ray: Bilaterally symmetrical perihilar reticular interstitial changes are seen 

• HRCT chest: Diffuse ground glass opacities 
• LDH increases.
• Increase A -a gradient.
• Confirmatory test: BAL stained with gomori methenamine silver stain which demonstrates the cysts.
• Rx: TMP - SMX (DOC for treatment and prevention)
• Other drugs: Pentamidine, Clindamycin, Primaquine, Atovaquone, steroids.

Organism Specific Approach for Pneumonia

• Alcoholism= S. pneumonia, Klebsiella Pneumoniae, oral anaerobes.
  • Klebsiella pneumonia in alcoholics causes Necrotizing Pneumonia that results in a feature of red currant Jelly sputum.
  • Oral anaerobes in alcoholics cause Necrotizing Pneumonia that results in lung abscess. Chest X-ray showing air fluid level S/O Lung abscess
  • Impaired airway defence seen in alcohol/drug intoxication, dementia, stroke, etc., cause of pneumonia is Oral anaerobes
  • Rx of oral anaerobes causing Pneumonia is clindamycin

• COPD: H. influenzae
• Lung abscess:  oral Anaerobes? Primary.
  • CA-MRSA ? Secondary to setting of foreign body, Tumor, Infection.
• Hotel stay / cruise : Legionella Pneumophila. (due to inhalation of water droplets)
• Infected Humans: SARS - COV 2
• Birds: H. capsulatum, C.pittaci
• Rabbits: F. tularensis. 
  • Tularemia is caused by the bacterium Francisella tularensis. 
  • Hunter after killing a rabbit develops Eschar/ ulcer and regional lymph node swelling.
  • Ulceroglandular fever: The most common form of tularemia and usually occurs following a tick bite or after handing of an infected animal. The ulcer is accompanied by swelling of regional lymph glands, usually in the armpit or groin.
• Sheep: Coxiella Brunetti / Q fever
  • Coxiella Brunetti cause atypical pneumonia and Endocarditis as well.

Rx of Atypical Pneumonia: Macrolides.

• BUN = UREA/2.14 
• E.g., BUN= 10, UREA = BUN x 2.14 = 10 x 2.14 = 21.4 mg/dl 
• Urea = BUN x 0.35
• E.g., BUN= 10, Urea = 10 x 0.35 = 3.5 mmol/L

• For group 1: OPD management is done
• For group 2: IPD management is done. E,g., 70 yrs old patient with elevated BUN RX: IV Augmentin with macrolides
• For group 3: ICU management is done
• If only age is >/= 65 and rest are normal. Treatment is based on health condition of patient the treating doctor can decide the type of management.
• If age along with another deranged parameter is given. Then admit patient and give parenteral antibiotics

Also Read: EPILEPSY AND Electroencephalography (EEG) : NEET PG Medicine

Treatment Strategy For C.A.P

• For outpatient management

For Inpatient Management

• Beta lactam+ macrolide or respiratory fluroquinolones (levofloxacin, moxifloxacin, Gemifloxacin)
• If recent hospitalization/ respiratory isolation
  • Add coverage for MRSA: Vancomycin/ linezolid & for pseudomonas: Piperacillin-Tazobactum

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