Utility of ampicillin-sulbactam for empiric treatment of ventilator-associated pneumonia in a trauma population

J Trauma. 2010 Oct;69(4):861-5. doi: 10.1097/TA.0b013e3181e83f8b.


Background: Ampicillin-sulbactam is guideline-recommended treatment for early-onset ventilator-associated pneumonia (VAP). However, intensive care unit clinicians are encountering increasing resistance to ampicillin-sulbactam. We sought to analyze the time period for early-onset VAP in our trauma population by using daily evaluation of resistance to ampicillin-sulbactam.

Methods: A retrospective cohort study was completed on all mechanically ventilated trauma patients admitted to a rural level-1 trauma center from January 2003 to December 2008 who were diagnosed with VAP. Daily bacterial resistance to ampicillin-sulbactam > 15% was defined as the threshold for early empiric antibiotic failure for the first episode of VAP. A univariate analysis of risk factors for multi-drug resistant pathogens (MDRPs) and comorbidities was completed to assess for predisposing factors for ampicillin-sulbactam resistance.

Results: One hundred sixty-three pathogens were identified in 121 trauma patients diagnosed with VAP. Of these isolates, 71% were gram-negative, 28% were gram-positive, and 1% was fungal. Methicillin-susceptible Staphylococcus aureus (23.9%), H aemophilus influenzae (20.9%), and Pseudomonas aeruginosa (11.7%) were the most common infecting organisms. Daily ampicillin-sulbactam resistance was 40%, 26%, 32%, 43%, 50%, and 60% on days 3 to 7 and ≥ 8 days, respectively. Only the presence of MDRP risk factors (89% vs. 65%, p < 0.01) and hospital LOS (36.8 [22.8-49.0] vs. 25.7 days [19.0-32.5], p < 0.01) was different between ampicillin- sulbactam resistant and ampicillin-sulbactam susceptible VAP groups. On univariate analysis, hospital length of stay >4 days and antibiotic use within 90 days were associated with ampicillin-sulbactam resistant VAP (p < 0.01).

Conclusions: Ampicillin-sulbactam is not an effective empiric therapy for early-onset VAP in our rural trauma population. The utility of ampicillin-sulbactam should be reviewed at other institutions to assess for appropriate empiricism.

MeSH terms

  • Adult
  • Aged
  • Ampicillin / therapeutic use
  • Anti-Bacterial Agents / therapeutic use*
  • Bacterial Infections / drug therapy*
  • Bacterial Infections / microbiology
  • Drug Resistance, Multiple, Bacterial*
  • Female
  • Guideline Adherence*
  • Haemophilus Infections / drug therapy
  • Haemophilus influenzae / drug effects
  • Humans
  • Intensive Care Units*
  • Male
  • Microbial Sensitivity Tests
  • Middle Aged
  • Pneumonia, Staphylococcal / drug therapy
  • Pneumonia, Ventilator-Associated / drug therapy*
  • Pneumonia, Ventilator-Associated / microbiology
  • Pseudomonas Infections / drug therapy
  • Pseudomonas aeruginosa / drug effects
  • Staphylococcus aureus / drug effects
  • Sulbactam / therapeutic use
  • Wounds and Injuries / drug therapy*


  • Anti-Bacterial Agents
  • sultamicillin
  • Ampicillin
  • Sulbactam