IC16 Lower Respiratory Tract Infections

Question 1

acute bronchitis: clinical presentation

Answer 1

Acute cough (<3 weeks)
Due to inflammation of trachea & lower airways

Question 2

acute bronchitis: diagnostic test

Answer 2

not required

Question 3

acute bronchitis: treatment

when to give AB

Answer 3

• Considered self-limiting; usually not recommended for treatment regardless of duration of cough
• To use AB only if bacterial infection suspected
  To perform further diagnostics to confirm bacterial infection ⇒ treat the infection (not acute bronchitis)
• Management of symptoms with pharmacological/ non-pharmacological methods

Question 4

acute bronchitis: monitoring outcomes

how long it lasts & when to see doctor

Answer 4

• Cough usually last for at least 3 weeks + AB use does not hasten resolution of cough
  Better to use cough suppressants as symptomatic treatment
• To see doctor if develop fever, SOB/ chest pain, cough increase in extent/ frequency or cough persisting beyond 3 weeks
  Possible bacterial superinfection

Question 5

pneumonia: background (description)

Answer 5

Infection of lung parenchyma
Due to proliferation of microbial pathogens in alveolar level

Question 6

pneumonia: risk factors

Answer 6

Smoking → suppressed neutrophil function & damages lung epithelium
Consists of MCC to remove pathogens by lungs/ GIT → damaged = loss of function of MCC

Chronic lung conditions: COPD, asthma, lung cancer
Destroys lung tissue → pathogens have more niduses for infection

Immune suppression: HIV, sepsis, glucocorticoids, chemotherapy
Suppression of immune response

Question 7

HAP/VAP: RF infection control

Answer 7

Lack of hand hygiene compliance
Contaminated respiratory care devices

Question 8

pneumonia: methods for exposure to pathogens

Answer 8

Aspiration of oropharyngeal secretions
Bacteria in oropharyngeal secretions enter lungs from mouth due to swallowing impairment
Substances flow from GIT to lungs → introduction of pathogen into respiratory tract
Inhalation of aerosols

Aerosol droplets containing bacteria

Haematological spreading
Bacteremia from extra-pulmonary source

Question 9

HAP/VAP: types of Risk factors

Answer 9

1. patient related
2. infection control
3. healthcare-associated

Question 10

pneumonia: effects of infection (process of getting pneumonia)

Answer 10

1. Exposure to pathogen via inhalation, aspiration, contagious or haematological mechanisms
   Normally cleared by innate immunity → but presence of risk factors lowers the ability of doing so
2. Susceptible host &/ or virulent pathogen
   May invade tissues ⇒ infection
3. Proliferation of microbe in lower airways & alveoli

Question 11

HAP/VAP: RF patient related

Answer 11

Elderly
Smoking
COPD, cancer, immunosuppression
Prolonged hospitalisation
Coma, impaired consciousness –> Inability to breathe independently
Malnutrition

Question 12

HAP/VAP: RF healthcare

Answer 12

• Prior AB use
  Altered normal flora; bacteria present can cause infection
• Sedatives
• Opioid analgesics
• Mechanical ventilation
  Bacteria can enter directly into lungs
  To ensure proper hand hygiene
• Supine position

Question 13

HAP/VAP: prevention

General; VAP specific

Answer 13

General
Practise consistent hand hygiene
Judicious use of AB & medications with sedative effects

VAP-specific
* Limit duration of mechanical ventilation → reduce risk of biofilm formation
To take off ventilator ASAP
* Minimise duration & deep levels of sedation
* Elevate head by 30 degrees (helps with breathing)

Question 14

pneumonia: classification definitions

CAP, HAP, VAP

Answer 14

CAP
Onset in community OR
<48 hours after hospital admissions

HAP
Onset ≥ 48 hours after hospital admission

VAP
Onset ≥ 48 hours after mechanical ventilation
Requires sedative drugs
Direct insertion of tubes into lungs

Question 15

CAP RF

Answer 15

History of pneumonia
Smoking, chronic respiratory diseases, immunosuppression

Question 16

CAP prevention method

Answer 16

Smoking cessation & immunisations (influenza & pneumococcal)

Question 17

CAP: causative organisms

General for all

Answer 17

Streptococcus pneumoniae
Haemophilus Influenzae

Atypical organisms
Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila

Question 18

CAP: causative organisms
inpatient, non-severe

Answer 18

based on risk factors, MRSA & Pseudomonas aeruginosa

Question 19

CAP: causative organisms
inpatient, severe

Answer 19

Staphylococcus aureus
Other Gram-negative bacilli: Klebsiella pneumonia, Burkholderia pseudomallei (High occurrence in tropical countries → derived from soil during rainy/ wet weathers)

Based on risk factors, MRSA & Pseudomonas aeruginosa

Question 20

HAP/VAP: causative organisms

also RF to lookout for; mortality risk

Answer 20

Pseudomonas
Staphylococcus aureus
Enterobacteriaceae spp
MRSA

RF
* MDRO risk factors
* Mortality risk factors → more sick = lower threshold to start on broad spectrum to target resistant strains

Question 21

HAP/ VAP possible outcomes

use of AB & hospitalisation

Answer 21

• Poor predictor of resistant pathogens/ worse outcomes
• Significant healthcare costs
  Prolonged hospitalisation
  Accounts ≥ 50% of inpatient antibiotic use
• Will have systemic + local signs & symptoms
• May lead to overuse of broad-spectrum AB
• Need to cover drug-resistant pathogens + de-escalate treatment if culture is negative

Question 22

CAP: risk stratification methods

Answer 22

1. CURBS-65
2. IDSA

Question 23

CAP: CURBS-65 Risk stratification

Criterias

Answer 23

Confusion
Urea >7 mmol/L
RR >30 bpm
BP (SBP <90mmHg, DBP <60mmHg)

Elderly >65 years

Question 24

CAP: CURBS-65 Risk stratification

scoring

Answer 24

• Score 0 or 1: outpatient
• Score 2: inpatient
• Score ≥ 3: inpatient, consider ICU
  Might require intubation due to breathlessness & low o2 levels

Question 25

CAP: IDSA criterias

Answer 25

Major & minor

Question 26

CAP: IDSA major criteria

Answer 26

* Mechanical ventilation Intubation required due to low o2 saturation * Septic shock requiring vasoactive medications Presence of hemodynamic instability To sustain BP

Question 27

CAP: IDSA minor criteria | RMOCLUHH

Answer 27

* **RR** ≥ 30 breaths/min * **PaO2/FiO2** ≤ 250 (ICU) * **Multilobar** infiltrates (X-ray) Might enter shock OR Require mechanical ventilation ⇒ major criteria * **Confusion**/disorientation * **Uremia** (urea > 7 mmol/L) * **Leukopenia** (WBC < 4 x 10^9/L) Not due to chemotherapy; must be due to infection * **Hypothermia** (core temperature < 36degC) * **Hypotension** requiring aggressive fluid resuscitation First line treatment Require vasopressors if do not work ⇒ major criteria

Question 28

CAP therapy: outpatient, no comorbidities | organism to cover + drug selection

Answer 28

Streptococcus pneumoniae PO **ꞵ-lactam: Amoxicillin 1 g q8H** High dose → precaution for penicillinase resistant streptococcus pneumoniae Narrow spectrum **Allergy or C/I for ꞵ-lactam** Respiratory FQ: levofloxacin/ moxifloxacin

Question 29

CAP therapy: outpatient, with comorbidities | organism to cover + drug selection

Answer 29

Streptococcus pneumoniae, Haemophilus influenzae (Atypical organisms) Mycoplasma pneumoniae, Chlamydophila Pneumoniae, Legionella pneumophila PO **1. ꞵ-lactam:** Amoxicillin/ clavulanate OR Cefuroxime ***PLUS (either one)*** **2. Macrolide**: clarithromycin OR azithromycin ADR: QTc prolongation **2. Doxycycline** Targets atypical organisms ADR: esophagitis & photosensitivity **Allergy or C/I for ꞵ-lactam** Respiratory FQ: levofloxacin/ moxifloxacin

Question 30

CAP therapy: inpatient, non-severe | organism to cover + drug selection

Answer 30

Same as CAP outpatient, with comorbidities but IV drug administration **MRSA risk factors** ADD ON IV Vancomycin OR IV/ PO linezolid **P.aeruginosa risk factors** Modify regimen to include pseudomonas coverage Piperacillin/tazobactam, Ceftazidime, Cefepime, Meropenem, Levofloxacin

Question 31

CAP therapy: inpatient, severe | organism to cover + drug selection

Answer 31

(same 5 key bacteria, with additional) Staphylococcus aureus, Klebsiella pneumonia, **Burkholderia pseudomallei** IV **1. ꞵ-lactam:** Amoxicillin/ clavulanate OR penicillin G PLUS **2. Ceftazidime** → covers H.influenzae & burkholderia pseudomallei PLUS **3. Macrolides:** clarithromycin OR azithromycin → Covers atypical & staphylococcus aureus **Alternative: Allergy or C/I for ꞵ-lactam** 1. Respiratory FQ: levofloxacin/ moxifloxacin PLUS 2. Ceftazidime **MRSA Risk factor** ADD ON IV Vancomycin OR IV/ PO linezolid

Question 32

CAP therapy: other treatment considerations Inclusion of anaerobic cover

Answer 32

If lung abscess/ empyema reported in radiology investigations **Possible additions:** IV/ PO metronidazole IV/ PO clindamycin → might have increased resistance in bacteroides fragillus

Question 33

CAP therapy: other treatment considerations Influenza management

Answer 33

* Add empiric oseltamivir (to current AB regimen) → if suspect influenza To initiate ASAP (best within first 48 hour, up to 5 days) of symptom onset * Patients with positive PCR Complete 5 days course of oseltamivir Consider discontinuing AB at 48-72 hours if no evidence of bacterial pathogen Negative cultures, low procalcitonin levels (<0.25), early clinical stability

Question 34

CAP therapy: other treatment considerations Respiratory FQ | reason why not first line therapy

Answer 34

**Increases AE** Tendonitis, tendon rupture, neuropathy, QTc prolongation, CNS disturbances, hypoglycemia **Development of resistance with overuse** **Important to preserve for other gram negative infections (levofloxacin & ciprofloxacin)** * Alternative Pseudomonas coverage with severe penicillin allergies * Only PO options for covering P.aeruginosa **May delay diagnosis of TB (differential diagnosis)** * FQ have activity against TB ⇒ cannot obtain proper sputum culture * Undesirable monotherapy if TB → causes resistance

Question 35

CAP therapy: other treatment considerations Adjunctive corticosteroid therapy

Answer 35

to reduce inflammation in lungs To add if shock resistant to fluid resuscitation & vasopressor support

Question 36

CAP therapy: Treatment duration Requirements for stopping after 5 days

Answer 36

Resolution of vital sign abnormalities * HR, RR, BP, oxygen saturation, temperature Ability to maintain oral intake Baseline mental status

Question 37

CAP therapy: de-escalation Suitable patients

Answer 37

Hemodynamically stable → normal BP, RR Improving clinically Ability to ingest oral medications

Question 38

CAP therapy: de-escalation methods | positive culture vs no positive culture

Answer 38

**Positive culture** Use AST to select narrower spectrum &/or PO AB(s) **No positive cultures** * De-escalation: empiric cover for MRSA, P.aeruginosa or burkholderia pseudomallei can be stopped in 48 hours if pathogen not isolated & patient improving * IV-to-oral: use same AB/ another AB from same class * General coverage: Strep pneumoniae, H.influenzae, atypical bacteria

Question 39

CAP therapy: Treatment duration Longer courses of AB therapy

Answer 39

* CAP complicated with other deep-seated infections ie: meningitis, lung abscess ⇒ requires ~2-3 weeks * Infection with other less common pathogens ie: Burkholderia pseudomallei, Mycobacterium tuberculosis or endemic fungi

Question 40

CAP therapy: Treatment duration

Answer 40

Minimum 5 days therapy 7 days if suspected/ proven MRSA or P.aeruginosa

Question 41

HAP/VAP: MRSA considerations

Answer 41

* Prior IV AB use within 90 days * Isolation of MRSA in 1 last year * Hospitalisation in unit where >20% S.aureus are MRSA * Prevalence of MRSA in hospital unknown, but patient is at high risk of mortality ie: need **ventilatory support** due to HAP & **Septic shock** * More sick = lower threshold to start on broad spectrum

Question 42

HAP/VAP: key organisms to cover

Answer 42

P.aeruginosa, staphylococcus aureus, enterobacteriales

Question 43

HAP/VAP: Pseudomonas & Gram negative cover

Answer 43

Use of double (2) antipseudomonal AB from different classes for empiric treatment of suspected HAP/ VAP in patients ⇒ to extend coverage * Risk factor for AM resistance Prior IV AB use within 90 days Acute renal replacement therapy prior to VAP onset (May get septic shock & renal function may stop) Isolation of P.aeruginosa in last 1 year * Hospitalisation in unit where >10% of pseudomonas are resistant to agent considered as monotherapy * Prevalence of P.aeruginosa in hospital unknown but patient is at high risk of mortality ie: need ventilatory support due to HAP & Septic shock * AVOID use of AG as sole antipseudomonal agent Sicker patients → bacteremia & pneumonia: may have higher mortality

Question 44

HAP/VAP: AB selections Pseudomonas aeruginosa Other Gram negative, enterobacter spp, klebsiella spp E.coli

Answer 44

1. ꞵ-lactam: * piperacillin/ tazobactam * Cefepime * Ceftazidime not preferred due to ESBL risk Avoid use if MRSA cover not required * Meropenem, imipenem **AND/OR** 2. Antipseudomonal FQ: Levofloxacin/ ciprofloxacin **OR** Aminoglycosides (amikacin) → partner agent; have breakpoint of pseudomonas

Question 45

HAP/VAP: AB selections MRSA

Answer 45

ADD ON IV vancomycin IV/ PO linezolid

Question 46

HAP/VAP: De-escalation suitable individuals

Answer 46

Hemodynamically stable → normal BP, RR Improving clinically Ability to ingest oral medications

Question 47

HAP/VAP: De-escalation methods | positive vs no positive culture

Answer 47

**Positive cultures** * Use AST to select narrower spectrum &/or PO AB(s) * For P.aeruginosa ⇒ to use single antipseudomonal agent The one that bacteria is susceptible **No positive cultures** * maintain coverage according to local HAP/VAP antibiogram OR (if antibiogram unavailable), P.aeruginosa, enterobacteriales, enteric Gram negative & MSSA * Removal of vancomycin if no MRSA indicated * May not be possible for patients with significant risk of MSSA * IV-to-oral conversion ⇒ ideal

Question 48

HAP/VAP: Treatment duration | when allowed to stop; when longer therapy required

Answer 48

7 days regardless of pathogen **Clinically stable; able to stop** * Resolution of vital sign abnormalities HR, RR, BP, oxygen saturation, temperature * HAP → Baseline mental status * VAP → can still be off AB even with ventilator on, as long as labs & vital signs are normal **Longer courses of AB therapy** * CAP complicated with other deep-seated infections ie: meningitis, lung abscess ⇒ requires ~2-3 weeks

Question 49

monitoring therapy of CAP, HAP & VAP | Therapeutic response, escalation of AB

Answer 49

* Most achieve clinical stability within first 48-72 hours elderly/ those with comorbidities may take longer * Should not escalate AB therapy in first 72 hours Unless culture-directed (current AB cannot cover bacteria) OR Significant clinical deterioration

Question 50

monitoring therapy of CAP, HAP & VAP | diagnostic tests

Answer 50

to repeat only if clinical deterioration To check for new pneumonia/ if pneumonia spread