ID: hospital-acquired and ventilator-associated pneumonia

hospital-acquired and ventilator-associated pneumonia (HAP/VAP)

• most common hospital acquired infection

  • VAP is just a type of HAP, but more specific

• associated with significant morbidity and mortality

• VAP increases ventilator days, length of stay, and costs

HAP diagnosis

• a pneumonia that develops ≥ 48 hours after admission to the hospital

  • intubation as a result of developing HAP is not a VAP

  • pneumonia developing < 48 hours after admission is a CAP

VAP diagnosis

• a pneumonia that develops ≥ 48 hours after intubation

  • impaired ability to protect their lungs

pathophysiology of VAP

1. colonization of the upper respiratory tract

2. host defenses are mechanically bypassed

   • this is because there is an impaired natural protection/clearance system due to the tube

3. organisms pass through tubing or past endotracheal cuff

4. increased risk of drug resistance

diagnosis of pneumonia

• dependent on a CXR (positive for infiltrates)

• quantitative sampling methods have bacterial count cutoffs for diagnosis

signs and symptoms

• new or worsening sputum production

• new or worsening cough

• increased respiratory rate

• pleuritic chest pain

• leukocytosis or leukopenia

• fever/hypothermia

• ascultatory changes (eg. rales, crackles)

• decrease in oxygenation

• worsening ventilator settings → due to worsening status (eg. administering to patient up to 100% pure oxygen)

  • increased FiO2

  • increased RR

  • worsening respiratory acidosis (CO2 accumulation)

non-invasive sampling types

• sputum (non-ventilated)

• tracheal aspirate

  • diagnostic threshold > 10⁵

• first-line sampling technique

invasive sampling types

• goes INTO the lungs

• bronchoalveolar lavage (BAL) → camera

  • diagnostic threshold > 10⁴

• miniBAL/microscopic BAL → no camera

  • diagnostic threshold > 10⁴

• protected specimen brush

  • diagnostic threshold > 10³

bronchoalveolar lavage (BAL)

• quantitative culture method

• a camera can go directly to where they think the infection is

• insertion of bronchoscope through the mouth or nose

• washing a part of the lung, which is collected for examination

sampling recommendations

• guidelines recommend AGAINST routine invasive sampling for VAP diagnosis

  • data suggests invasive sampling does not improve clinical outcomes vs non-invasive sampling

  • more well-designed studies are needed

• if invasive sampling is performed, antibiotics should be held if colony counts are below diagnostic thresholds

• culture results of non-invasive sampling should guide HAP antibiotic treatment

• don’t use invasive sampling with HAP, mostly with VAP

  • invasive sampling is more so used to find out the infection, rather than to decrease the risk of mortality

procalcitonin recommendations

• for the initiation of antibiotics:

  • it should NOT be used for the initiation of therapy vs clinical criteria alone

• for the discontinuation of antibiotics:

  • procalcitonin may be used to guide the discontinuation of antibiotics

bacteria that cause HAP/VAP

• Staphylococcus aureus (MSSA and MRSA)

• Pseudomonas aeruginosa

• Klebsiella pneumoniae

• E. coli

• Enterobacter spp.

• Acinetobacter bauannii

empiric therapy HAP/VAP

• should be guided by local susceptibilities

  • consider what is good for treatment at your specific hospital

  • VAP-specific antibiograms

• regimens should be active against S. aureus (not necessarily MRSA) AND P. aeruginosa as well as other gram-negatives

empiric coverage of MRSA for HAP/VAP patients

• recommended for patients with:

  1. prior IV antibiotic exposure in the past 90 days

  2. patient is at high risk for mortality

     • septic shock

     • ventilatory support for HAP

  3. unit methicillin-resistant rate is > 10-20% for S. aureus

empiric coverage of MRSA for VAP patients (only)

• hospitalization ≥ 5 days

• acute respiratory distress syndrome preceding VAP

• acute renal replacement therapy prior to VAP onset

agents for MRSA coverage

• options:

  • linezolid

  • vancomycin

• both agents hold equal weight in guidelines, however, there is a stronger recommendation for linezolid

  • additionally, linezolid had lower rates of nephrotoxicity, higher rates of clinical cure, and no difference in mortality

• remember, daptomycin is NOT applicable in the lungs due to inactivation by surfactant

empiric coverage

• EVERYONE needs coverage against MSSA and P. aerginosa

• coverage should be modified based on:

  • high-risk mortality (septic shock or ventilatory support for HAP)

  • previous IV antibiotic use (within 90 days)

  • VAP only:

    • local resistance rates > 10%

    • ARDS

    • acute renal replacement therapy

    • hospitalization ≥ 5 days

combination gram-negative coverage

• guidelines committee recommends this in patients with risk factors for MDR organisms or at high risk for mortality

  • this typically involves a ß-lactam + an aminoglycoside OR fluoroquinolone that cover P. aeruginosa

    • typically tobramycin is used! (amikacin and gentamicin don’t cover P. aeruginosa in a meaningful way)

• inadequate therapy leads to increased mortality in VAP

empiric treatment for HAP

1. patient develops pneumonia ≥ 48 hours following admission

2. if they develop septic shock, require ventilatory support, or received IV antibiotics within 90 days, they need MRSA coverage + double coverage for resistant gram-negatives

   • this could look like linezolid + cefepime + tobramycin

3. if not, look at the local MRSA prevalence

4. if the MRSA prevalence is > 20%, they need MRSA coverage + anti-pseudomonal ß-lactam/monobactam

5. if the local MRSA coverage < 20%, the patient can receive anti-pseudomonal ß-lactam

empiric treatment for VAP

1. if the patient develops pneumonia ≥ 48 hours following intubation, they need MRSA coverage + double coverage for resistant gram-negatives

   1. unless:

      • hospitalization < 5 days

      • not in septic shock

      • no IV antibiotics in the past 90 days

      • no ARDS

      • not on any renal replacement therapy

      • gram negative resistance to a single agent is < 10%

      • S. aureus resistance is < 10-20%

duration of therapy

• previous guidelines recommend 7-days of therapy UNLESS the patient was infected with a non-fermenting organism (P. aeruginosa, A. baumannii, S. maltophilia)

• 7 days is adequate therapy, provided the patient is clinically improving

inhaled antibiotics in VAP

• guidelines recommend these adjunctive aminoglycosides or polymyxins for organisms susceptible only to those agents, over systemic agents alone

• meta-analysis also shows increased rates of clinical cute with these adjunctive therapies