Pneumonia for NEET PG Medicine: Organisms, CURB-65, ICMR Antibiotics, Hospital and Aspiration Pneumonia, Legionella, Influenza

Start Here

🎯 Exam priority: High. Expect: commonest organism, CURB-65 components and cut-offs, Indian first-line antibiotic, why fluoroquinolones are avoided in India, HAP/VAP timing and organisms, aspiration site, Legionella clues and PCP in advanced HIV.

CBME mapping: GM 3.1–3.22. Lung pathology is in Pathology article 19; antibiotics in Pharmacology; TB in Medicine article 7.

Pneumonia types and organisms, CURB-65 and ICMR treatment. Drawn by TrackNation.

Community-Acquired Pneumonia

• Organisms: S. pneumoniae is the commonest in all ages and settings; also H. influenzae, atypicals (Mycoplasma, Chlamydia pneumoniae, Legionella) and viruses. S. aureus (including MRSA) and Pseudomonas need specific risk factors. Psittacosis follows exposure to parrots and related birds.

• Signs: fever, tachypnoea, tachycardia, crackles, bronchial breath sounds, egophony. In the elderly: confusion.

• Tests (admitted patients): blood cultures, sputum Gram stain and culture, urinary pneumococcal and Legionella antigens, HIV screening; chest X-ray.

• Severity: CURB-65 (CRB-65 without urea in primary care).

Treatment: the ICMR Workflow

• Upper respiratory infection and acute bronchitis: symptomatic care; antibiotics only for clear indications (amoxicillin for acute follicular tonsillitis; purulent sputum with leukocytosis in bronchitis).

• In India, fluoroquinolones are not used for CAP because their anti-tubercular activity can mask tuberculosis.

• Non-invasive ventilation may help CAP with respiratory failure. Discharge when eating, afebrile and stable for at least 48 hours.

Other Pneumonias

• Hospital-acquired: ≥ 48 hours after admission — S. aureus, Pseudomonas and other gram-negatives; resistance is a concern. Ventilator-associated: ≥ 48 hours after intubation — gram-negative bacilli and S. aureus.

• Aspiration: chemical pneumonitis from sterile gastric contents; aspiration pneumonia and lung abscess from oral secretions with anaerobes. Shadows sit in dependent segments — superior or posterior basal segments of a lower lobe, posterior segment of an upper lobe.

• Immunocompromised: in advanced HIV (low CD4) — Pneumocystis jirovecii, Toxoplasma, CMV, fungi, mycobacteria.

• Legionella: lives in fresh water and building water systems; labs show hyponatraemia, hypophosphataemia and raised transaminases; urinary antigen detects serogroup 1 only.

• Influenza: incubation 1–4 days (average 48 hours); antigenic drift causes yearly variants; complications include primary viral and secondary bacterial pneumonia; neuraminidase inhibitors (oseltamivir, zanamivir, peramivir) or baloxavir.

Traps the Examiner Sets

• Commonest CAP bug everywhere: pneumococcus.

• CURB-65: urea ≥ 19 mg/dL BUN, RR > 30, SBP < 90 or DBP ≤ 60, age ≥ 65.

• India: no fluoroquinolone for CAP (masks TB).

• HAP/VAP = after 48 hours.

• Pneumonia + low sodium + water-system exposure → Legionella.

Memory Hooks & Shortcuts

Shortcuts to lock in this article's numbers and lists. Each one only re-packages facts proven above.

• 🧠 CURB-65 = Confused Urea Rises, Breathing fast, BP drops, 65 — CURB-65

• 🧠 0-1 home, 2 hospital, 3+ high (ICU at 4-5) — CURB-65 action

• 🧠 In India 'No FQ for CAP' — Fluoroquinolones Quieten TB — fluoroquinolones

• 🧠 HAP/VAP: 48 hours = 2 days in → hospital bugs (Staph, Pseudomonas) — HAP/VAP

• 🧠 Legionella: Low sodium, Loves water, Lab urine antigen — Legionella

• 🧠 Aspiration falls Down and Back (dependent segments) — aspiration

Rapid-Revision Cards

• Commonest CAP organism

  S. pneumoniae.

• Atypicals

  Mycoplasma, Chlamydia pneumoniae, Legionella.

• CURB-65

  Confusion, BUN ≥ 19, RR > 30, SBP < 90/DBP ≤ 60, age ≥ 65.

• CURB-65 0–1

  < 3% death; outpatient.

• CURB-65 2

  9%; consider admission.

• CURB-65 ≥ 3

  15–40%; admit; ICU at 4–5.

• Primary-care score

  CRB-65.

• ICMR OPD CAP

  Amoxicillin (or erythromycin/doxycycline), 5 days.

• ICMR OPD CAP + comorbidity

  Amoxicillin + azithromycin.

• No fluoroquinolones (India)

  Anti-TB activity masks TB.

• Pseudomonas cover

  Cefepime, ceftazidime, pip-taz, meropenem.

• ICMR referral

  CRB-65 > 1, SpO2 ≤ 92% (≤ 50 y), multilobar, confusion.

• HAP

  ≥ 48 h after admission; S. aureus, Pseudomonas.

• VAP

  ≥ 48 h after intubation; GNB, S. aureus.

• Aspiration sites

  Superior/posterior basal lower lobe; posterior upper lobe.

• Lung abscess

  Aspiration; anaerobes.

• Advanced HIV pneumonia

  Pneumocystis jirovecii.

• Legionella

  Water systems; hyponatraemia; urinary Ag serogroup 1.

• Influenza drugs

  Neuraminidase inhibitors; baloxavir.

• Psittacosis

  Birds; Chlamydia psittaci.

Sources

Facts in this article were checked against these documents.

• MSD Manual Professional: Overview of Pneumonia; Community-Acquired Pneumonia; Hospital-Acquired Pneumonia; Ventilator-Associated Pneumonia; Aspiration Pneumonitis and Pneumonia; Pneumonia in Immunocompromised Patients; Lung Abscess — Merck & Co. (MSD Manuals), reviewed 2025–26 (link)

• MSD Manual Professional: Legionella Infections; Influenza — Merck & Co. (MSD Manuals), reviewed 2026 (link)

• Standard Treatment Workflow: Acute Respiratory Infection in Adults — ICMR / Department of Health Research, MoHFW, 2019 (link)

• Competency Based Undergraduate Curriculum, General Medicine (GM 3) — National Medical Commission, 2024

Test Yourself: Practice Questions

Thirty questions in NEET PG style, most of them clinical vignettes.

Practice Questions (NEET PG pattern)

Original questions written in the style of the exam: +4 for a correct answer, −1 for a wrong one. Every answer was checked against the sources listed above. NEET PG papers are not published by NBEMS, so these are not past-paper questions.

Q1. The commonest organism causing community-acquired pneumonia in all age groups is

• (a) Klebsiella pneumoniae

• (b) Staphylococcus aureus

• (c) Mycoplasma pneumoniae

• (d) Streptococcus pneumoniae

Q2. Which group lists the atypical causes of community-acquired pneumonia?

• (a) Mycoplasma, Chlamydia pneumoniae, Legionella

• (b) Pneumococcus, Haemophilus, Moraxella

• (c) S. aureus, MRSA, Streptococcus pyogenes

• (d) Pseudomonas, Klebsiella, E. coli

Q3. A 72-year-old with pneumonia is confused, BUN 25 mg/dL, respiratory rate 32/min, BP 100/70 mm Hg. Her CURB-65 score is

• (a) 2

• (b) 3

• (c) 4

• (d) 5

Q4. A CURB-65 score of 1 indicates

• (a) death risk < 3% — outpatient treatment is usually appropriate

• (b) need for mechanical ventilation

• (c) risk of death 40%

• (d) ICU admission

Q5. With a CURB-65 score of 3 or more, mortality risk is about

• (a) > 80%

• (b) < 3%

• (c) 9%

• (d) 15–40%

Q6. In primary care without blood tests, the ICMR workflow scores pneumonia severity using

• (a) APACHE II

• (b) CRB-65

• (c) SOFA

• (d) PSI

Q7. A 30-year-old with no comorbidity has mild CAP (CRB-65 = 0). Per ICMR, the first-line antibiotic is

• (a) IV meropenem

• (b) levofloxacin

• (c) oral ciprofloxacin

• (d) oral amoxicillin 500 mg three times a day

Q8. A diabetic outpatient with CAP should, per ICMR, receive

• (a) moxifloxacin

• (b) amoxicillin alone for 3 days

• (c) IV amikacin

• (d) amoxicillin plus azithromycin

Q9. Why does the ICMR workflow advise against fluoroquinolones for CAP?

• (a) they are too expensive

• (b) they are inactive against pneumococcus

• (c) they cause hypokalaemia

• (d) their anti-tubercular activity can mask TB

Q10. Per ICMR, corticosteroids in non-severe CAP are

• (a) not given unless another medical indication exists

• (b) first-line

• (c) routine

• (d) given to all inpatients

Q11. A hospitalised CAP patient with bronchiectasis and chronic steroid use needs cover for Pseudomonas. A suitable ICMR choice is

• (a) erythromycin

• (b) doxycycline

• (c) piperacillin–tazobactam

• (d) oral amoxicillin

Q12. Which feature is an ICMR criterion to refer a CAP patient to a higher centre?

• (a) multilobar consolidation on chest X-ray

• (b) temperature 38 °C alone

• (c) mild sore throat

• (d) cough for 3 days

Q13. In a patient aged under 50 with CAP, the ICMR SpO2 threshold for referral is

• (a) ≤ 98%

• (b) ≤ 70%

• (c) ≤ 80%

• (d) ≤ 92%

Q14. Pneumonia developing 4 days after admission for a hip fracture is

• (a) aspiration pneumonitis by definition

• (b) community-acquired pneumonia

• (c) hospital-acquired pneumonia

• (d) ventilator-associated pneumonia

Q15. The commonest organisms in hospital-acquired pneumonia are

• (a) S. aureus and Pseudomonas with other gram-negatives

• (b) Mycoplasma and Chlamydia

• (c) Pneumocystis and CMV

• (d) pneumococcus and Haemophilus

Q16. Ventilator-associated pneumonia is defined as pneumonia arising

• (a) only in children

• (b) within 6 hours of intubation

• (c) at least 48 hours after endotracheal intubation

• (d) after discharge

Q17. A patient with a decreased level of consciousness aspirates and develops pneumonia. The usual sites are

• (a) the apices only

• (b) the lingula only

• (c) the anterior segments

• (d) superior or posterior basal segments of a lower lobe, or posterior segment of an upper lobe

Q18. Inhaling a large volume of sterile gastric contents causes

• (a) Pneumocystis pneumonia

• (b) chemical pneumonitis

• (c) lung abscess immediately

• (d) Legionella pneumonia

Q19. The commonest organisms in a lung abscess after aspiration are

• (a) Pneumocystis

• (b) influenza virus

• (c) anaerobic bacteria

• (d) Mycoplasma

Q20. A patient with advanced HIV (very low CD4 count) has bilateral pneumonia. A classic opportunistic cause is

• (a) Mycoplasma

• (b) Legionella only

• (c) Pneumocystis jirovecii

• (d) Streptococcus pneumoniae only

Q21. A pneumonia cluster is traced to a contaminated building water system; patients have low sodium, low phosphate and raised transaminases. The organism is

• (a) Klebsiella

• (b) Legionella

• (c) Mycoplasma

• (d) pneumococcus

Q22. The Legionella urinary antigen test detects

• (a) all Legionella species

• (b) L. pneumophila serogroup 1 only

• (c) pneumococcus

• (d) Mycoplasma

Q23. Oseltamivir acts on influenza by

• (a) blocking DNA polymerase

• (b) inhibiting neuraminidase

• (c) inhibiting endonuclease

• (d) inhibiting reverse transcriptase

Q24. The average incubation period of influenza is

• (a) 48 hours (range 1–4 days)

• (b) 2 weeks

• (c) 6 hours

• (d) 1 month

Q25. Minor progressive mutations of influenza haemagglutinin and neuraminidase producing yearly variants are called

• (a) phase variation

• (b) antigenic shift

• (c) antigenic drift

• (d) reassortment pandemics

Q26. A bird keeper develops pneumonia. The organism to consider is

• (a) Chlamydia psittaci

• (b) Coxiella only

• (c) Legionella

• (d) Pneumocystis

Q27. An elderly patient with pneumonia may present mainly with

• (a) diarrhoea only

• (b) confusion

• (c) joint swelling

• (d) rash

Q28. A patient with suspected CAP also has frank haemoptysis. The ICMR workflow says this may suggest

• (a) pulmonary TB or malignancy

• (b) bronchitis

• (c) viral URI

• (d) asthma

Q29. Which test is part of the work-up for a patient admitted with CAP?

• (a) urinary VMA

• (b) urinary pneumococcal and Legionella antigens

• (c) D-dimer

• (d) serum amylase

Q30. Per ICMR, a CAP inpatient can be discharged when

• (a) CRP is normal

• (b) after 14 days of IV antibiotics

• (c) eating, afebrile and haemodynamically stable for at least 48 hours

• (d) the chest X-ray is completely clear

Active Recall

From memory: list CAP organisms; give the CURB-65 components and what each score means; state the ICMR outpatient and inpatient regimens, why fluoroquinolones are avoided and the referral criteria; define HAP and VAP with organisms; describe aspiration, lung abscess, PCP, Legionella and influenza features.