JC14 (Medicine) - Lower respiratory tract infections Flashcards

Question

Specific pathogen that cause opportunistic infection and pneumonia in HIV patients

Answer 1

Pneumocystis jirovecii patients with HIV or severe immunocompromised state (eg. post-chemo)

Answer 2

CURB-65 Confusion Urea \> 7mmol/L Respiratory rate \> 30/min Blood pressure: SBP \< 90 or DBP \<60 Age \> 65 0 or 1 = home treatment 2 or more factors = immediate hospital admission 3 or more = ICU

Answer 3

1. Oxygen therapy - all patients with resp. failure - Target SaO2 \> 92% - High concentration oxygen/ CPAP/ Mechanical ventilation 2. Fluid rehydration 3. Antibiotics coverage 4. Analgesia for pleuritic pain - simple analgesics 5. Manage complications

Answer 4

- Admin within 6-8 hours, duration 7-10d - All CAP needs Strep. pneumoniae coverage; All severe CAP needs Legionella pneumophila coverage Typical pathogen: □ Penicillin + β-lactamase inhibitor → Eg. augmentin Atypical pathogens: □ ± macrolide or tetracycline → Eg. clarithromycin (klacid), azithromycin, doxycycline

Answer 5

□ Recent or frequent Abx use □ Recent or frequent hospitalization □ Nursing home resident □ Immunocompromised state

Answer 6

- Outpatient CAP PO amoxicillin-clavulanate (Augmentin) ± macrolide or doxycycline - Moderate inpatient CAP PO/IV amoxicillin-clavulanate (Augmentin) ± macrolide or doxycycline Alternatives: IV ceftriaxone or cefotaxime ± macrolide or doxycycline - Severe inpatient CAP IV piperacillin-tazobactam (Tazocin) or ceftriaxone or cefepime ± macrolide or doxycycline

Answer 7

Chest physiotherapy: helps expectoration clinical review 6 weeks later CXR if persistent S/S or suspect underlying malignancy

Answer 8

→ Complications, eg. abscess, parapneumonic effusion → Alternative dx, eg. ILD, TB → Underlying cause, eg. obstruction, recurrent aspiration

Answer 9

□ Respiratory failure □ Lung abscess □ Pathogen Spread: → Septicaemia with multi-organ failure → Parapneumonic effusion → Empyema thoracis □ Systemic effects: → Electrolyte abnormalities, eg. hypoNa due to SIADH → Cardiac complications: acute MI, cardiac arrhythmia (esp AF)

Answer 10

→ Underlying structural disease, eg. bronchial obstruction, bronchiectasis → Host factors, eg. recurrent aspiration, immunocompromised state

Answer 11

pneumonia occurring ≥48h after hospitalization + excluding incubating infection at admission aspiration of oropharyngeal secretions colonized by hospital-acquired organisms

Answer 12

□ General debility and old age □ Smoking and COPD □ ↑risk of aspiration: post-GA, nasogastric tube □ ↓gastric aciditiy: antacids, H2 blockers (↑GI colonization) □ Mechanical ventilation (ventilator-associated pneumonia (VAP))

Answer 13

□ Early onset (\<4-5d of admission): similar to CAP □ Late-onset: → Gram - bacilli, eg. Escherichia, Klebsiella spp → Non-fermenters, eg. Pseudomonas, Acinetobacter baumanii → Multi-resistant bacteria, eg. MRSA → Anaerobes, eg. Bacteroides

Answer 14

Early onset: 3rd generation cephalosporin OR β-lactam/β-lactamase inhibitor (Augmentin, Unasyn) Late onset: Anti-pseudomonal β-lactam/β-lactamase inhibitor (Tazocin) OR Anti-pseudomonal cephalosporin (Cefepime [4G]) OR Anti-pseudomonal carbapenem (imipenem, meropenem) ± aminoglycoside OR fluoroquinolone ± vancomycin after careful assessment of indications

Answer 15

pneumonia due to aspiration of a relatively large amount of material

Answer 16

□ Impaired gag reflex: ↓GCS, alcoholism, bulbar palsy, vocal cord palsy, terminal illness □ Regurgitation/vomiting: dysphagia and oesophageal diseases, vomiting, drowning □ Others: severe dental infection or URTI, tracheo-esophageal fistula

Answer 17

□ Chemical pneumonitis due to aspiration of acidic materials □ Infection by oropharyngeal flora → Anaerobes, eg. Bacteroides, Porphyromonas, Prevotella, Fusobacterium → Others: Streptcoccus, S. aureus, G- bacilli

Answer 18

□ CXR: consolidations, usually in dependent parts of lungs → Lower lobes (classically recurrent RLL pneumonia) → Posterior segments of upper lobe (if recumbent) □ VFSS for swallowing problems → Follow-up CXR shows contrast medium in lung fields

Answer 19

□ Treatment of underlying conditions □ Abx to cover oropharyngeal flora: augmentin ± metronidazole □ Non-oral feeding (eg. PEG tube, NG tube) → prevent further aspiration

Answer 20

Rapid antigen test on nasopharyngeal aspirate RT-PCR Viral Culture Serology

Answer 21

Incubation period: 1-4 days □ Systemic: fever (37.8-40oC), myalgia, arthralgia, malaise □ URTI: running nose, sore throat, cough, sputum

Answer 22

Notable influenza types: Human: H1N1 (Spanish), H2N2 (Asian), H3N2 (Hong Kong) Avian: H5N1, H7N7, H7N9 Swine: H1N1

Answer 23

Pneumonia: primary viral or superimposed bacterial (S. pneumoniae, S. aureus, esp \>65y) GI involvement: vomiting, diarrhea CNS involvement: encephalitis, transverse myelitis, aseptic meningitis, GBS Others: myositis, myocarditis, pericarditis, Reye’s syndrome

Answer 24

□ General: personal hygiene, symptomatic Tx, droplet precaution □ Neuraminidase inhibitors: effective in both flu A/B Examples: oseltamivir (Tamiflu, PO 75mg BD x5d), zanamivir (Relenza, 10mg BD inhaler puff x5d) MoA: inhibit neuraminidase → cannot cleave sialic acid on cell surface → interfere with release of progeny → decrease viral propagation

Answer 25

pathological dilatation of bronchi

Answer 26

□ Congenital: → Cystic fibrosis (rare in Chinese) → Ciliary dysfunction: eg. ciliary dyskinesia, Kartagener syndrome → Predisposition to infections (eg. 1o hypoγglobulinemia) □ Acquired: → Previous infections, eg. TB, suppurative pneumonia, childhood measles or pertussis → Obstruction, eg. foreign body, tumours → Rhuematic disorders, eg. RA, Sjogren’s syndrome → Gastro-esophageal reflux (leading to chronic aspiration) → Lung fibrosis (leading to traction bronchiectasis)

Answer 27

Chronic course (years) with acute infective exacerbations - Cough (98%): chronic, persistent - Daily sputum production (78%): copious, tenacious, purulent, foul-smelling - Haemoptysis (27%): only streaks of blood - Exertional dyspnoea ± wheezes - Pleuritic pain - Systemic symptoms: weight loss, fatigue, anorexia

Answer 28

□ General: cachexia, clubbing, halitosis □ Varies with severity: - Coarse crackles that disappear/change in quality after coughing - Obstructive pattern → ↓breath sounds, ↓chest wall movement - Chronic localized fibrosis → bronchial breath sounds - Cor pulmonale (↑JVP, peripheral oedema, hepatic congestion, parasternal heave, loud P2) - Respiratory failure (central cyanosis)

Answer 29

COPD: also with recurrent bouts of dyspnoea, productive cough, wheezes, coarse crackles Asthma: also with recurrent exacerbation of dyspnoea, productive cough and wheezes Lung fibrosis: also with dyspnoea, cough, crackles and finger clubbing

Answer 30

CXR: only abnormal in 50% → Ring shadows: dilated bronchi seen from front → Tramline shadows: dilated bronchi seen from side (usually in lower lobes) → Tubular shadows: dilated bronchi filled with secretions → Cystic dilatation ± fluid levels in severe cases

Answer 31

1) Thickened, dilated airways (ring shadows) - Wider than accompanying arterioles (signet ring sign) - No peripheral tapering with visible peripheral airway ≤1cm of pleural lining 2) Mucus plugging (darker than airway wall): - Air-fluid levels visible within cystic dilatation of airway - Tree-in-bud appearance when peripheral airways are involved 3) Atelactasis, consolidation, abscesses

Answer 32

→ Immunoglobulins and neutrophil function test for immunodeficiency → Auto-Ab (eg. RF) for autoimmune diseases → Ba studies or 24h oesophageal pH monitoring for aspiration causes → Ciliary and sperm analysis for primary ciliary dyskinesia → Sweat test for cystic fibrosis

Answer 33

Potential organisms: H. influenzae, S. aureus, P. aeruginosa (if long-standing) □ Choice of Abx: → Anti-pseudomonal penicillins (first-line), eg. piperacillin-tazobactam (tazocin) → 3rd and 4th generation cephalosporin, eg. ceftazidime → Carbapenems, eg. meropenem, imipenem → Aminoglycosides, eg. amikacin → Fluoroquinolones, eg. levofloxacin □ Duration: recommend 14 days

Answer 34

□ Treatment of underlying aetiology, eg. GERD, immunodeficiency □ Long-term (≥3mo) antibiotics for immunomodulatory effect to decrease exacerbations - Oral Macrolides □ Airway clearance: - Chest physiotherapy - Expectorant or mucolytic □ Adjuncts: - Bronchodilators (esp β-agonist): for SOB and obstructive pattern, bronchospasm - Inhaled corticosteroids (not routine) □ Surgery (rare) → Excision of bronchiectactic areas (eg. lobectomy) → Percutaneous embolization of bronchial vessels

JC14 (Medicine) - Lower respiratory tract infections Flashcards

(58 cards)