LRTI Flashcards
Symptoms of acute bronchitis?
Acute cough <3w
Should antibiotics be used for treatment of bronchitis?
No
What is pneumonia?
Infection of lung parenchyma, affects alveolar level
How can bacteria enter the lower respiratory tract to cause pneumonia?
- aspiration of oropharyngeal secretion
- inhalation of aerosols
- bacteremia from extra-pulmonary sources
Risk factors of pneumonia?
- smoking: suppress neutrophil function & damage lung epithelium
- chronic lung conditions: COPD, asthma, lung cancer
- immunosuppression: e.g. HIV, chemotherapy, steroids
What radiographic tests can be done to diagnose pneumonia? What would be seen in pneumonia?
Chest X-ray, lung CT, lung ultrasonography
New infiltrates or dense consolidations (unilateral white patches)
What lab test is recommended for severe CAP or hospitalised patients? What is its limitation?
Urinary antigen tests for strep pneumo, legionella
Limitation: remains +ve for days-weeks despite abx tx
What sample should be collected for gram-stain and culture?
Respiratory gram-stain and culture
- sputum (but usually contaminated by oropharyngeal secretions)
- lower respiratory tract samples (invasive sampling)
Blood cultures: rule out bacteraemia
When should samples be collected for gram-stain and cultures?
Hospitalised:
- severe CAP
- risk factors for drug-resistant pathogens (MRSA, pseudomonas) -> empirically treated for pathogens, prev infected with pathogens in last 1y, hospitalised or received parenteral abx in last 90 days
What are the classifications of pneumonia?
- Community-acquired pneumonia (CAP): onset in community or <48h after hospital admission
- Hospital-acquired pneumonia (HAP): onset ≥48h after hospital admission
- Ventilator-associated pneumonia (VAP): onset ≥48h after mechanical ventilation
How to prevent CAP?
- smoking cessation
- immunisations (influenza, pneumococcal)
What are the common pathogens that cause CAP (outpatient, inpatient non-severe)?
- strep pneumo
- H influenzae
- atypicals (e.g. mycoplasma pneumo, chlamydophila pneumo, legionella)
- inpatient: includes MRSA & pseudomonas based on risk factors
What are the common pathogens that cause CAP (inpatient severe)?
- strep pneumo
- H influenzae
- atypicals (e.g. mycoplasma pneumo, chlamoydophila pneumo, legionella)
- MRSA & pseudomonas based on risk factors
- staph aureus
- gram -ve: Klebsiella, burkholderia pseudomallei
For inpatients with suspected pneumonia, what else should they be tested for?
Influenza during circulating seasons
Risk stratification for CAP?
- pneumonia severity index (PSI)
- CURB-65
- major and minor (IDSA)
What is CURB-65?
1 point each:
- confusion (new onset)
- urea > 7mmol/L
- RR ≥30
- BP < 90/60
- ≥65y
[0-1: outpatient; 2: inpatient; ≥3: inpatient, ICU]
What are the major and minor criterias for CAP? What would be considered severe CAP?
Major:
- mechanical ventilation
- septic shock requiring vasoactive meds
Minor
- RR ≥30
- PaO2 / FiO2 ≤250
- multi lobar infiltrations
- confusion / disorientation
- urea > 7mmol/L
- WBC < 4 x 10^9
- < 36C temp
- hypotension requiring aggressive fluid resuscitation
Severe CAP: ≥1 major criteria OR ≥3 minor criteria
Empiric treatment for pneumonia outpatient, no comorbidities? Target what organism?
Target: strep pneumo
Either one:
- PO amoxicillin (high dose)
- PO levofloxacin/moxifloxacin
Empiric treatment for CAP outpatient, with comorbidities? Target what organism?
Target: strep pneumo, H influenzae, atypicals
Either one:
- PO augmentin/cefuroxime + PO clarithromycin/azithromycin/doxycycline
- PO levofloxacin/moxifloxacin
Empiric treatment for CAP inpatient, non-severe? Target what organism?
Target: strep pneumo, H influenzae, atypicals + MRSA/pseudomonas if have risk factors
Either one:
- IV augmentin/cefuroxime/ceftriaxone + IV clarithromycin/azithromycin/doxycycline (PO)
- IV levofloxacin/moxifloxacin
If MRSA:
- IV vancomycin OR linezolid
- risk factors: resp isolation of MRSA in last 1y, hospitalisation/parenteral abx in last 90 days + MRSA PCR screen +ve
If pseudomonas:
- modify regimen to include pseudomonas coverage: pip-taco, ceftazidime, cefepime, meropenem, levofloxacin
- risk factors: resp isolation of pseudomonas in last 1y
Empiric treatment for CAP inpatient, severe? Target what organism?
Target: strep pneumo, H influenzae, atypicals, S aureus, gram -ve (Klebsiella, Burkholderia pseudomallei) + MRSA/pseudomonas if have risk factors
Either one:
- IV augmentin/penicillin G + IV clarithromycin/azithromycin + IV ceftazidime
- IV levofloxacin/moxifloxacin + IV ceftazidime
If MRSA:
- IV vancomycin OR linezolid
- risk factors: resp isolation of MRSA in last 1y, hospitalisation/parenteral abx in last 90 days
If pseudomonas:
- regimen already covers (ceftazidime)
- risk factors: resp isolation of pseudomonas in last 1y, hospitalisation/parenteral abx in last 90 days
What covers Burkholderia pseudomallei?
Ceftazidime
Can you double cover bacteria?
No -> double check regimen if there is double coverage!!
When to include anaerobic coverage for CAP?
Lung abscess or empyema in radiology investigations
What to add for anaerobic coverage if no anaerobic coverage in regimen?
Metronidazole, clindamycin
If suspect influenza, what to add?
Oseltamivir within 48h of onset, up to 5 days
For CAP, if no positive cultures and patient improving, what to do with abx?
Stop empiric cover for MRSA, pseudomonas and burkholderia pseudomallei in 48h
For the other abx, convert to PO (of same class if no PO form)
Treatment duration of CAP?
5 days (7 days if suspect MRSA or pseudomonas)
Should abx therapy be escalated in the first 72h?
No, unless culture-directed or significant clinical deterioration
Need to repeat radiographic investigations?
No need if patient improves clinically, need if clinical deterioration
How to prevent HAP/VAP?
- Hand hygiene
- VAP: limit duration of mechanical ventilation, minimise duration & deep levels of sedation, elevate head of bed by 30 degrees
What to cover for HAP/VAP?
- pseudomonas
- S aureus
+ MRSA
+ gram -ve (E coli, Enterobacter, Klebsiella)
When to cover MRSA for HAP/VAP?
- prior IV abx use within 90D
- isolation of MRSA in last 1y
- hospitalisation in a unit where >20% of S aureus is MRSA
- prevalence of MRSA In hospital is not known but pt is at high risk for mortality (need ventilatory support due to HAP & septic shock)
Empiric treatment for HAP/VAP?
- antipseudomonal beta lactam (pip-tazo, cefepime, ceftazidime, meropenem, imipenem)
- antipseudomonal FQ (levofloxacin, ciprofloxacin)
- aminoglycoside (amikacin, gentamicin)
+ MRSA if have risk factor: vancomycin, linezolid
double antipseudomonal agents if have risk factors
When to use 2 antipseudomonal abx from diff classes?
- risk factor for antimicrobial resistance (prior IV use within 90D, acute renal replacement therapy prior to VAP onset, isolation of Pseudomonas in last 1y)
- hospitalisation in a unit where >10% pseudomonas isolates are resistant to an agent being considered for monotherapy
- prevalence of pseudomonas is unknown but pt is at high risk for mortality (need for ventilatory support due to HAP & septic shock)
Can use aminoglycosides as sole antipseudomonal agent for HAP/VAP?
No
Why avoid ceftazidime and ciprofloxacin for pseudomonas cover in HAP/VAP if MRSA cover is omitted?
No gram +ve cover (MSSA)
For HAP/VAP, if have positive culture for pseudomonas, what to de-escalate to?
One anti-pseudomonal agent that bacteria is susceptible to
For HAP/VAP, if no positive cultures, what to de-escalate to?
Maintain coverage according to local HAP/VAP antibiogram
Duration of treatment for HAP/VAP?
7 days
