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

Source: https://tracknation.in/story/pneumonia-for-neet-pg-medicine-organisms-curb-65-icmr-antibiotics-hospital-and-aspiration-pneumonia-legionella-influenza (TrackNation — free UPSC notes with PYQs)

> NEET PG Medicine: community-acquired pneumonia organisms and signs, CURB-65 and CRB-65, the ICMR adult respiratory infection workflow (antibiotics, no fluoroquinolones, referral rules), hospital-acquired, ventilator and aspiration pneumonia, lung abscess, Pneumocystis, Legionella and influenza, with a diagram, hooks, vignette MCQs and cards.

## 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).

| **CURB-65 point**

 | **Criterion**

 |
| C

 | Confusion

 |
| U

 | Urea: BUN ≥ 19 mg/dL (6.8 mmol/L)

 |
| R

 | Respiratory rate > 30/min

 |
| B

 | SBP < 90 or DBP ≤ 60 mm Hg

 |
| 65

 | Age ≥ 65

 |
| Score 0–1

 | Death risk < 3% — outpatient

 |
| Score 2

 | 9% — consider admission

 |
| Score ≥ 3

 | 15–40% — admit; ICU at 4–5

 |

## 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.

| **Setting (ICMR ARI STW)**

 | **Treatment**

 |
| Outpatient CAP, no comorbidity

 | Amoxicillin 500 mg TDS, or erythromycin, or doxycycline — 5 days

 |
| Outpatient CAP with comorbidity

 | Amoxicillin 500 mg TDS + azithromycin 500 mg OD; 7–10 days if slow response

 |
| Do not give

 | Fluoroquinolones (anti-TB activity, can mask TB); steroids unless otherwise indicated

 |
| Ward (non-ICU)

 | IV beta-lactam; add oral macrolide for atypicals, comorbidity or recent antibiotics

 |
| Suspected Pseudomonas

 | Cefepime, ceftazidime, piperacillin–tazobactam or meropenem (± amikacin)

 |
| Refer if

 | CRB-65 > 1, low SpO2, multilobar shadows, confusion, hypothermia, frank haemoptysis

 |

## 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

- S. pneumoniae.

- Mycoplasma, Chlamydia pneumoniae, Legionella.

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

- < 3% death; outpatient.

- 9%; consider admission.

- 15–40%; admit; ICU at 4–5.

- CRB-65.

- Amoxicillin (or erythromycin/doxycycline), 5 days.

- Amoxicillin + azithromycin.

- Anti-TB activity masks TB.

- Cefepime, ceftazidime, pip-taz, meropenem.

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

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

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

- Superior/posterior basal lower lobe; posterior upper lobe.

- Aspiration; anaerobes.

- Pneumocystis jirovecii.

- Water systems; hyponatraemia; urinary Ag serogroup 1.

- Neuraminidase inhibitors; baloxavir.

- 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

**Answer: (d)** — Atypicals and viruses are also common.

**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

**Answer: (a)** — Plus viruses.

**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

**Answer: (c)** — Confusion, urea, respiratory rate, age — BP does not score.

**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

**Answer: (a)** — Score 2 → consider admission.

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

- (a) > 80%

- (b) < 3%

- (c) 9%

- (d) 15–40%

**Answer: (d)** — Admit; consider ICU with 4–5.

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

- (a) APACHE II

- (b) CRB-65

- (c) SOFA

- (d) PSI

**Answer: (b)** — CURB-65 without urea.

**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

**Answer: (d)** — Erythromycin or doxycycline are alternatives; 5 days.

**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

**Answer: (d)** — Comorbidities change the regimen.

**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

**Answer: (d)** — TB is common in India.

**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

**Answer: (a)** — Not recommended in non-severe CAP.

**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

**Answer: (c)** — Also cefepime, ceftazidime, meropenem.

**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

**Answer: (a)** — Also CRB-65 > 1, low SpO2, confusion, hypothermia.

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

- (a) ≤ 98%

- (b) ≤ 70%

- (c) ≤ 80%

- (d) ≤ 92%

**Answer: (d)** — < 90% in those over 50.

**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

**Answer: (c)** — HAP = at least 48 hours after admission.

**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

**Answer: (a)** — Resistance is a major concern.

**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

**Answer: (c)** — Gram-negative bacilli and S. aureus dominate.

**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

**Answer: (d)** — Aspiration.

**Q18.** Inhaling a large volume of sterile gastric contents causes

- (a) Pneumocystis pneumonia

- (b) chemical pneumonitis

- (c) lung abscess immediately

- (d) Legionella pneumonia

**Answer: (b)** — Bacterial aspiration pneumonia differs.

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

- (a) Pneumocystis

- (b) influenza virus

- (c) anaerobic bacteria

- (d) Mycoplasma

**Answer: (c)** — From oral secretions.

**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

**Answer: (c)** — Also Toxoplasma, CMV, fungi, mycobacteria.

**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

**Answer: (b)** — Lives in fresh water and building plumbing.

**Q22.** The Legionella urinary antigen test detects

- (a) all Legionella species

- (b) L. pneumophila serogroup 1 only

- (c) pneumococcus

- (d) Mycoplasma

**Answer: (b)** — A negative test does not exclude other serogroups.

**Q23.** Oseltamivir acts on influenza by

- (a) blocking DNA polymerase

- (b) inhibiting neuraminidase

- (c) inhibiting endonuclease

- (d) inhibiting reverse transcriptase

**Answer: (b)** — Baloxavir is the endonuclease inhibitor.

**Q24.** The average incubation period of influenza is

- (a) 48 hours (range 1–4 days)

- (b) 2 weeks

- (c) 6 hours

- (d) 1 month

**Answer: (a)** — Mild cases resemble a cold.

**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

**Answer: (c)** — Shift is a major change.

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

- (a) Chlamydia psittaci

- (b) Coxiella only

- (c) Legionella

- (d) Pneumocystis

**Answer: (a)** — Psittacosis is rare.

**Q27.** An elderly patient with pneumonia may present mainly with

- (a) diarrhoea only

- (b) confusion

- (c) joint swelling

- (d) rash

**Answer: (b)** — Delirium carries higher mortality.

**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

**Answer: (a)** — Frank haemoptysis is also a referral criterion.

**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

**Answer: (b)** — Also blood and sputum cultures and HIV screening.

**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

**Answer: (c)** — X-ray clearing lags behind recovery.

### 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.