How should patients with hospital-associated pneumonia (HAP) be empirically treated under the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society?

Although empiric selection of antibiotics should be based on the local distribution of pathogens associated with HAP and their antimicrobial susceptibilities, routine coverage of Staphylococcus aureus (not necessarily methicillin-resistant S. aureus [MRSA]) and Pseudomonas aeruginosa or other gram-negative bacilli is recommended1.

In patients not at high risk of mortality (including ventilatory support and septic shock) or risk for MRSA (i.e.prior IV antibiotic use within 90 days, hospitalization in a unit where >20% of S. aureus isolates are MRSA or the prevalence of MRSA is unknown), piperacillin-tazobactam, cefepime, levofloxacin, imipenem or meropenem alone is suggested.

In patients not at high risk of mortality but with factors that increase the likelihood of MRSA, piperacillin-tazobactam, cefepime/ceftazidime, ciprofloxacin/levofloxacin, imipenem/meropenem, or aztreonam, plus vancomycin or linezolid should be considered.

In patients at high risk of mortality or receipt of IV antibiotics during the prior 90 days vancomycin or linezolid plus 2 of the following should be used: piperacillin-tazobactam, cefepime/ceftazidime, ciprofloxacin/levofloxacin, imipenem/meropenem, amikacin/gentamicin/tobramycin, or aztreonam are recommended (avoid double β-lactams).

In patients with structural lung disease increasing the risk of gram-negative infections (ie, bronchiectasis or cystic fibrosis), double anti-pseudomonal coverage is recommended.

 

Reference

  1. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis, Advance Access published July 14, 2016.
How should patients with hospital-associated pneumonia (HAP) be empirically treated under the 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society?

What are some of the major changes in the 2016 Infectious Diseases Society of America and the American Thoracic Society guidelines on pneumonia in hospitalized patients?

The most noticeable change is the elimination of the concept of health-care associated pneumonia (HCAP) altogether1. This action is in part related to the fact that many patients with HCAP were not at high risk for multi-drug resistant organisms (MDROs) , and that individual patient risk factors, not mere exposure to healthcare facilities, were better determinant of  the need for broader spectrum antimicrobials.

Other noteworthy points in the guidelines include:

  • Although hospital-associated pneumonia (HAP) is still defined as a pneumonia not incubating at the time of admission and occurring 48 hrs or more following hospitalization, it now only refers to non-VAP cases; VAP cases are considered a separate category.
  • Emphasis is placed on each hospital generating antibiograms to guide providers with respect to the optimal choice of antibiotics.
  • Despite lack of supportive evidence, the guidelines recommend obtaining respiratory samples for culture in patients with HAP.
  • Prior intravenous antibiotic use within 90 days is cited as the only consistent risk factor for MDROs, including methicillin-resistant Staphylococcus aureus (MRSA) and Pseudomonas sp.

 

Reference

  1. Kalil AC, Metersky ML, Klompas M, et al. Management of adults with hospital-acquired and ventilator-associated pneumonia: 2016 clinical practice guidelines by the Infectious Diseases Society of America and the American Thoracic Society. Clin Infect Dis 2016 ;63:e61-e111.  Advance Access published July 14, 2016. https://www.ncbi.nlm.nih.gov/pubmed/27418577
What are some of the major changes in the 2016 Infectious Diseases Society of America and the American Thoracic Society guidelines on pneumonia in hospitalized patients?

What is the sensitivity of nose swabs in detecting methicillin-resistant Staphylococcus aureus (MRSA) pneumonia?

In MRSA pneumonia, the sensitivity of nasal swab PCR may vary from as low as 24.2% to 88% (1-3). A single center  study involving  patients with possible healthcare-associated pneumonia (HCAP) and a low clinical pulmonary infection score (CPIS) — for whom antibiotics may not be necessary anyway (4)—suggested that discontinuation of empiric vancomycin in patients without an adequate respiratory culture and a negative nose and throat culture may be reasonable (5).  However, a prospective study of ICU patients concluded that “clinicians cannot reliably use the results of initial negative MRSA nasal swab results to withhold empirical MRSA coverage from patients who otherwise are at risk for MRSA infection” (3).

Thus, there is currently insufficient data to support discontinuation of vancomycin based on a negative nasal screen alone, particularly in patients who may be at high risk of MRSA pneumonia.

 

References

  1. Rimawi RH, Ramsey KM, Shah KB, et al. Correlation between methicillin-resistant Staphylococcus aureus nasal sampling, and S. aureus pneumonia in the medical intensive care unit. Infect Control Hosp Epidemiol 2014;35:590-92.
  2. Dangerfield B, Chung A, Webb B, et al. Predictive value of methicillin-resistant Staphylococcus aureus (MRSA) nasal swab PCR assay for MRSA pneumonia. Antimicrob Agents Chemother 2014;58:859-64.
  3. Sarikonda KV, Micek ST, Doherty JA, et al. Methicillin-resistant Staphylococcus aureus nasal colonization is a poor predictor of intensive care unit-acquired methicillin-resistant Staphylococcus aureus infections requiring antibiotic treatment. Crit Care Med 2010;38:1991-1995.
  4. Napolitano LM. Use of severity scoring and stratification factors in clinical trials of hospital-acquired and ventilator-associated pneumonia. Clin Infect Dis 2010;51:S67-S80.
  5. Boyce JM, Pop O-F, Abreu-Lanfranco O, et al. A trial of discontinuation of empiric vancomycin therapy in patients with suspected methicillin-resistant Staphylococcus aureus health care-associated pneumonia. Antimicrob Agents Chemother 2013;57:1163-1168.
What is the sensitivity of nose swabs in detecting methicillin-resistant Staphylococcus aureus (MRSA) pneumonia?

Is there any utility in screening for methicillin-resistant Staphylococcus aureus (MRSA) colonization when selecting empiric antibiotic therapy for skin and soft tissue infections (SSTIs)?

The reported rates of MRSA colonization in patients with community-associated MRSA SSTI have been surprisingly low, ranging from 7% to 41% (55% among hospitalized patients) (1), making it difficult to exclude MRSA as a causative pathogen based on a negative screening test alone. The concordance between what grows from the nares and what is isolated from the SSTI site is also far from ideal.  Among patients with methicillin-sensitive S. aureus (MSSA) SSTI , 12% may be colonized with MRSA and of those with MRSA SSTI, 32% may be colonized with MSSA (1).  In the absence of a reliable screening test to help us select an empiric antibiotic regimen in patients with SSTI, we should pay special attention to the clinical features of the SSTI.  Empiric MRSA antibiotic coverage should be considered for patients with purulent SSTIs, deep tissue infections, or those with systemic toxicity( 2), irrespective of colonization status.  

1. Ellis MW, Schlett CD, Millar EV, et al. Prevalence of nasal colonization and strain concordance in patients with community-associated Staphylococcus aureus skin and soft tissue infections. Infect Control Hosp Epidemiol 2014;35:1251-6.

2. Liu C, Bayer A, Cosgrove SE, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis 2011;52:e18-55.2.

 

Is there any utility in screening for methicillin-resistant Staphylococcus aureus (MRSA) colonization when selecting empiric antibiotic therapy for skin and soft tissue infections (SSTIs)?

Should we routinely cover for methicillin-resistant Staphylococcus aureus (MRSA) when treating patients for cellulitis?

β-hemolytic streptococci (BHS) are usually considered the primary cause of non-purulent cellulitis (e.g. without abscesses, or infections involving deep soft tissues, wounds, or ulcer) even in the MRSA era. In a prospective study of patients admitted to the hospital for “diffuse,  non-culturable “(i.e. many of our patients), most had serological evidence of acute  BHS, and >95% responded to a β-lactam antibiotic treatment (1) .  The current Infectious Diseases Society of America guidelines do not endorse empiric coverage of  MRSA for non-purulent cellulitis,  unless there is systemic toxicity or poor response to  β-lactam  monotherapy (2). More specifically, the guidelines recommend a  β-lactam antibiotic for treatment of non-purulent cellulitis in hospitalized patients with modification to MRSA coverage if no clinical response. One advantage to β-lactam monotherapy is the ease of switch to an equivalent oral antibiotic (e.g. cephalexin) when transitioning from parenteral antibiotic therapy.  

1. Jeng A, Beheshti M, Li J, et al. The role of beta-hemolytic streptococci in causing diffuse nonculturable cellulitis: a prospective investigation. Medicine (Baltimore) 2010;89:217-26.

2. Liu C, Bayer A, Cosgrove SE, et al. Clinical practice guidelines by the Infectious Diseases Society of America for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children. Clin Infect Dis 2011;52:e18-55.

 

Should we routinely cover for methicillin-resistant Staphylococcus aureus (MRSA) when treating patients for cellulitis?

Is the “8 day rule” for treatment of healthcare-associated pneumonia (HCAP) appropriate irrespective of etiologic agent?

Not necessarily.  In fact, the original study showed more relapses among patients with Pseudomonas aeruginosa nosocomial pneumonia treated for 8 days compared to 15 days, and concluded that the results did not apply to “non-fermenting gram negative bacilli” (1). For methicillin-resistant Staphylococcus aureus (MRSA) pneumonia, the data on the effectiveness of the shorter course therapy is quite limited (1,2) .  So for patients with pneumonia due to organisms such as P. aeruginosa or MRSA I routinely extend the course of antibiotics to at least 2 weeks.

1. Chastre J, Wolff M, Fagon JY. Comparison of 8 vs 15 days of antibiotic therapy for ventilator-associated pneumonia in adults: a randomized trial. JAMA 2003;290:2588-98. 

2. Rubinstein E, Kollef MH, Nathwani D. Pneumonia caused by methicillin-resistant Staphylococcus aureus. Clin Infect Dis 2008;46 (Suppl5):S378-385.

Is the “8 day rule” for treatment of healthcare-associated pneumonia (HCAP) appropriate irrespective of etiologic agent?