LRTI

Question 1

Outline the different categories of pneumonia and their definitions

Answer 1

Community acquired pneumonia: onset in the community or <48 h of hospital admission

Hospital acquired pneumonia: onset >= 48 h of hospital admission

Ventilator associated pneumonia: onset >= 48h of mechanical ventilation

Question 2

Name the risk factors for pneumonia (general and CAP/HAP/VAP specific)

Answer 2

general: smoking, chronic lung conditions (e.g. asthma, COPD, lung cancer), immunocompromised (e.g. HIV, sepsis, glucocorticoids, chemotherapy), increased exposure to pathogen

CAP: history of pneumonia

HAP/VAP: healthcare related factors (e.g. prolonged hospitalisation, malnutrition, impaired consciousness, use of sedatives/opioid analgesics, mechanical ventilation, supine position), infection control factors (e.g. lack of hand hygiene compliance, contaminated respiratory care devices)

Question 3

Describe the clinical presentations of pneumonia (signs and symptoms, radiographical evidence, labs)

Answer 3

signs and symptoms:

general systemic: fever, chills, malaise, rigors, tachycardia, hypotension, change in mental status (elderly)

local: productive cough, shortness of breath, tachypnea (RR>22bpm), chest pain, hypoxia

physical examination findings:
inspiratory crackles on auscultation, diminished breath sounds over affected area, accessory lung muscle use

chest x ray: new infiltrates or dense consolidations in the lung

general laboratory findings: increase in WBC, C-reactive protein, pro-calcitonin etc.

Question 4

When should pre-treatment respiratory gram stain and cultures, and blood cultures be obtained for CAP (as per IDSA guidelines)?

Answer 4

When patient is classified under inpatient severe, or inpatient non-severe but have risk factors for MRSA or Pseudomonas (resp. isolation of pathogen in the past yr, or hospitalization/parental antibiotic use in last 90 days and positive for PCR screen) or Pseudomonas aeruginosa (resp. isolation of pathogen in the past yr)

Question 5

What are the stratified categories for the empiric treatment of CAP?

Answer 5

1. outpatient, no-comorbidities
2. outpatient, with comorbidities (e.g. lung/heart/liver/kidney disease, DM, alcoholism, malignancy, asplenia)
3. inpatient, non-severe
4. inpatient, severe

Question 6

Describe the variables and the scoring system for CURB-65, used to stratify CAP patients according to the severity of their condition

Answer 6

1 point each:
- Confusion (new onset)
- Uremia (urea >7mmol/L)
- Respiratory rate >30bpm
- Blood pressure low (SBP<90 mmHg or DBP <60 mmHg)
- Age >= 65 years old

score:
0-1: outpatient
2: inpatient
3: inpatient, consider ICU

Question 7

Describe the IDSA/ATS criteria for severe CAP?

Answer 7

Severe CAP: presence of >=1 major criteria OR >=3 minor criteria

major criteria: mechanical ventilation (intubation), septic shock requiring vasoactive medications

minor criteria: confusion/disorientation, uremia (urea >7mmol/L), respiratory rate >30bpm, hypotension requiring fluids resuscitation, leukopenia (WBC < 4 x 10^9/L), PaO2 =< 250, hypothermia (body temp <36 degrees)

Question 8

What are the key pathogens for empiric treatment for CAP - outpatient, no-comorbidities?

Answer 8

S. pneumonia

Question 9

What are the key pathogens for empiric treatment for CAP - outpatient, with co-morbidities

Answer 9

S. pneumoniae
H. influenza
Atypicals: Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophilla

Question 10

What are the key pathogens for empiric treatment for CAP - inpatient, non-severe?

Answer 10

S. pneumonia
H. influenza
Atypicals: Mycoplasma pneumoniae, Chlamydia pneumoniae, Legionella pneumophilla

To cover MRSA and Pseudomonas aeruginosa if risk factors are present -
MRSA risk factors for inpatient, non-severe CAP: respiratory isolation of MRSA within the past 1 year, hospitalisation/parental antibiotic use in the last 90 days and positive MRSA PCR screen test

Pseudomonas aeruginosa risk factors for inpatient, non-severe CAP: respiratory isolation of Pseudomonas aeruginosa within the last 1 year

Question 11

What are the key pathogens to cover for empiric treatment of CAP - inpatient, severe

Answer 11

S. pneumoniae
H. influenza
Atypicals: Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophilla

S. aureus
Other gram-negative bacilli: Klebsiella pneumoniae
Burkholderia pseudomallei

To cover for MRSA and Pseudomonas aeruginosa if risk factors are present:

MRSA risk factors for inpatient, severe CAP: respiratory isolation of pathogen in the last year, hospitalisation/parentera antibiotic use in the last 90 days

Pseudomonas aeruginosa risk factors for inpatient, severe CAP: respiratory isolation of pathogen in the last year, hospitalisation/parenteral antibiotic use in the last 90 days

Question 12

What are the key pathogens to cover for empiric treatment of HAP/VAP?

Answer 12

S. aureus (MSSA)
Pseudomonas aeruginosa
Other gram negative enteric bacteria: Enterobacter spp., Klebsiella spp., E. coli

To cover for MRSA if risk factors present: isolation of MRSA (can be anywhere in the body, not limited to respiratory) in the last year, parenteral antibiotic use in the last 90 days, hospitalisation in an unit where >20% of S. aureus are MRSA (i.e. Singapore hospitals), prevalence of MRSA unknown but patient has mortality risk factors (on mechanical ventilation/VAP, shock)

Question 13

Describe the empiric treatment regime for CAP - outpatient, no co-morbidities

Answer 13

First line: beta lactam monotherapy
Amoxicillin PO 1g q8h

2nd line: respiratory FQ monotherapy
Levofloxacin PO 750mg OD
Moxifloxacin PO 400mg OD

Question 14

Describe the empiric treatment regime for CAP - outpatient, with co-morbidities (heart/lung/liver/kidney disease, DM, alcoholism, asplenic, malignancy)

Answer 14

First line: beta-lactam + macrolide / doxycycline
Amoxicillin-clavulanate PO 625mg q8h OR PO 1g q12h
Cefuroxime PO 500mg q12h
+
Clarithromycin PO 500mg q12h
Azithromycin PO 500mg q24h
Doxycycline PO 100mg q12h

Second line: respiratory FQ monotherapy
Levofloxacin PO 750mg OD
Moxifloxacin PO 400mg OD

Question 15

Describe the empiric treatment regime for CAP - inpatient, non-severe?

Answer 15

first line: beta-lactam + macrolide/ doxycycline
Amoxicillin-clavulanate PO 625mg q8h OR PO 1g q12h OR IV 1.2g q8h
Cefuroxime PO 500mg q12h
Ceftriaxone IV 1-2g q24h
+
Clarithromycin PO/IV 500mg q12h
Azithromycin PO/IV 500mg q24h
Doxycycline PO 10mmg q12h

second line: respiratory FQ monotherapy
Levofloxacin PO/IV 750mg OD
Moxifloxacin PO/IV 400mg OD

if need to cover for MRSA, add
Vancomycin IV 25-30mg/kg q8-12h, with LD of 15mg/kg
Linezolid IV/PO 600mg q12h

if need to cover for Pseudomonas aeruginosa,
- modify beta-lactam component to include:
Piperacillin-tazobactam IV 4.5g q6-8h
Cefepime IV 2g q8h
Meropenem IV 1g q8h
Imipenem-cilastin IV 500mg q6h
Ceftazidime IV 2g q8h (however, ceftazidime cannot be given as monotherapy, as it does not cover S. pneumoniae)

• or if on respiratory FQ monotherapy, change to / remain on levofloxacin IV/PO 750mg OD

Question 16

Describe the empiric treatment regime for CAP - inpatient, severe?

Answer 16

first line: beta-lactam + macrolide + ceftazidime
Amoxicillin-clavulanate IV 1.2g q8h
+
Clarithromycin IV 500mg q12h
Azithromycin IV 500mg q14h
+
Ceftazidime IV 2g q8h

second line: respiratory FQ + ceftazidime
Levofloxacin IV 750mg q24h
Moxifloxacin IV 400mg q24h
+
Ceftazidime IV 2g q8h

if need to cover for MRSA, to add on:
Vancomycin IV 25-30mg/kg, q8-12h, with an LD of 15mg/kg
Linezolid IV/PO 600mg q12h

if need to cover for Pseudomonas aeruginosa, no need to modify therapy as ceftazidime in the above regimens already covers

Question 17

When is anaerobic coverage required for empiric treatment of CAP? and what is the treatment regimen?

Answer 17

Presence of lung abscess and / or empyema (collection of pus in the pleural cavity)

To add Metronidazole PO/IV
Clindamycin PO/IV

Question 18

Describe the management of influenza in CAP?

Answer 18

if suspected influenza, add oseltamivir 75 mg BD x 5 days, on top of antibacterial empiric treatment regimen. If results come back positive for influenza PCR and no other evidence of bacterial pathogen (negative bacterial culture, low procalcitonin level, early clinical stability), then consider discontinuing antibiotics at 48-72h

Question 19

When can adjunctive corticosteroid therapy by considered in the treatment of CAP?

Answer 19

only add if patient is experiencing shock refractory to vasopressors and fluid resuscitation (ICU patients that are extremely severe); otherwise, do not routinely add

Question 20

When can we de-escalate/perform IV-to-Oral conversion for CAP empiric regimens?

Answer 20

When patient is hemodynamically stable (normalisation of vital signs, e.g. HR, BP, RR, PaO2, temperature, able to maintain oral intake, adequate baseline mental status), improving clinically

Question 21

How can we de-escalate/perform IV-to-Oral conversion for CAP empiric regimens?

Answer 21

Empiric cover for MRSA, Pseudomonas aeruginosa and Burkholderia Pseudomallei (for inpatient, severe) can be stopped at 48h if these pathogens are not isolated in culture and patient is improving

For IV-to-Oral conversion, use either same antibiotic/antibiotic from same class, while maintaining adequate coverage

Question 22

What is the duration of therapy for all CAP

Answer 22

5 days, extend to 7 days if treating for MRSA/Pseudomonas aeruginosa

Longer course of 3-6 weeks needed if treating for Burkholderia pseudomallei, lung abscess, meningitis etc. (CAP complicated with other deep seated infections)

Question 23

Describe the empiric regimen for HAP/VAP

Answer 23

first line: anti-pseudomonal beta-lactam +/- anti-pseudomonal FQ
Piperacillin-tazobactam IV 4.5g q6-8h
Cefepime IV 2g q8h
Meropenem IV 1g q8h
Imipenem-cilastin IV 500mg q6h
Ceftazidime IV 2g q8h (cannot use if MRSA coverage is not included, as strong S. aureus coverage will be missing; also avoided as it drives ESBL production and hence resistance in gram negative bacteria)

+/-
Ciprofloxacin PO 500mg q12h or IV 400mg q8-12h
Levofloxacin PO/IV 750mg q24h

another anti-pseudomonal option:
Amikacin IV 15-20mg/kg q24h
(cannot use as sole anti-pseudomonal agent)

if need to cover MRSA, to add on:
Vancomycin IV 25-30mg/kg q8-12h, with LD of 15mg/kg
Linezolid IV/PO 600mg q12h

*indication for double anti-pseudomonal coverage, any one of the following:
- risk factor for resistance to pseudomonas (parental antibiotic use in the past 90 days, acute RRT prior to VAP onset, isolation of Pseudomonas aeruginosa in the last year)
- hospitalisation in unit where >10% of Pseudomonas aeruginosa is resistant to agent considered for monotherapy
- presence of pseudomonas aeruginosa is not known but patient is at high risk for mortality (i.e. need mechanical ventilation/VAP, septic shock)

Question 24

When to perform de-escalation/IV-to-oral conversion for HAP/VAP empiric regimen?

Answer 24

When patient is hemodynamically stable (normal vital signs, e.g. HR, RR, BP, PaO2, temperature, able to maintain oral intake, adequate baseline mental status), improving clinically

Question 25

How to perform de-escalation/IV-to-Oral conversion for HAP/VAP empiric regimen?

Answer 25

If positive culture (at 48-72h):
- if patient was previously on double anti-pseudomonal therapy, can discontinue and treat the patient with a susceptible anti-pseudomonal agent (that has >90% susceptibility)
- if no MRSA isolated, can remove MRSA coverage

If NO positive culture (at 48-72h):
- keep double anti-pseudomonal therapy
- if no MRSA isolated, can remove MRSA coverage

IV to oral conversion if possible

Question 26

What is the treatment duration for HAP/VAP?

Answer 26

7 days, regardless of pathogen present

Longer course of 3-6 weeks needed for HAP/VAP complicated with other deep seated infections, e.g. meningitis, lung abscess

Question 27

Is repeat CXR needed to confirm resolution of CAP/HAP/VAP?

Answer 27

No, as radiological improvement lags behind clinical improvement. Only repeat if there is clinical deterioration.

Question 28

What are the specific measures to prevent CAP?

Answer 28

Smoking cessation
Immunization (influenza and pneumococcal)

Question 29

What are the specific measures to prevent HAP/VAP

Answer 29

Consistent hand hygiene
Judicious use of antibiotics and medications with sedative effects
VAP: minimize the duration of mechanical ventilation, minimize the duration of sedation and deep sedation, elevate the head of the bed by 30 degrees