Empiric Methicillin Resistant Staphylococcus aureus Coverage in the Early Ventilator Associated Pneumonia Window: If and When

Time to Look for Another Infectious Source? White Blood Cell Trends during Ventilator-Associated Pneumonia

Background: Ventilator-associated pneumonia (VAP) continues to plague patients in intensive care units (ICUs) throughout the world. Persistent leukocytosis despite antibiotic treatment for VAP can have many etiologies including normal inflammatory response, inadequate VAP antimicrobial therapy, and the presence of additional infectious diagnoses. Hypothesis: Surgical patients with VAP and a second infectious source have a different white blood cell count (WBC) trend than patients with VAP alone. Patients and Methods: Retrospective, single-center study of surgical ICU patients diagnosed with VAP (>10⁴ CFU/mL on semi-quantitative culture) between January 2019 and June 2020. Chart review identified additional infections diagnosed during VAP treatment. White blood cell count values were compared between patients treated for VAP alone (VAP-alone) and those with additional infections (VAP-plus) using a Wilcoxon test. Univariable analysis compared admission type, surgeries, and steroid use between cohorts. Results: Eighty-eight VAPs were included for analysis; 61 (69%) were VAP-alone and 27 (31%) VAP-plus. Average age was 47.1 ± 16.7 years, 78% were male, and 93% were trauma admissions. Median hospital day of VAP diagnosis was six (interquartile range [IQR], 4-10). Nearly all patients (99%) were started on initial antibiotic agents to which the VAP organism was sensitive. Daily WBC was higher for VAP-plus compared with VAP-alone on days five, six, and seven of treatment. The maximum WBC was higher for VAP-plus (21.6 k/mcL vs. 16.1 k/mcL; p = 0.02). There were no differences in admission types, number of surgeries, or steroid use between groups. Conclusions: Providers should have increased suspicion for additional sources of infection when ICU patients with a VAP continue to have elevated WBC despite appropriate antibiotic therapy.

Methicillin-Resistant Staphylococcus aureus Pneumonia in Critically Ill Trauma and Burn Patients: A Retrospective Cohort Study

BACKGROUND

The timing and risk factors for methicillin-resistant Staphylococcus aureus (MRSA) pneumonia in trauma patients are not well characterized. This information is critical for the selection of appropriate empiric antibiotics. The objective of this study was to determine the incidence of MRSA pneumonia in early-onset and late-onset pneumonia and to identify risk factors for MRSA in the trauma-burn intensive care unit (ICU).

PATIENTS AND METHODS

We conducted a retrospective cohort study from January 2012 to March 2015 of patients in the trauma and burn ICU with clinical and microbiologic evidence of pneumonia. Demographics, injury type and severity, co-morbidities, antimicrobial agents, and MRSA nasal colonization at ICU admission were extracted from the medical record. A multi-variable exact logistic regression was performed to assess predictors of MRSA pneumonia.

RESULTS

Eighty patients with 88 episodes of pneumonia were included in the cohort. Ten patients had MRSA pneumonia, an overall incidence of 11.4% of pneumonia episodes with a median onset of seven days. The proportion of MRSA pneumonia episodes was not significantly different in early-onset (<5 days) or late-onset pneumonia, and there were no statistically significant risk factors for developing MRSA pneumonia. The majority of patients with MRSA had at least one known risk factor including homelessness, substance abuse, and receipt of broad-spectrum antibiotic agents.

CONCLUSIONS

The 11.4% overall incidence of MRSA pneumonia in this trauma-burn cohort was similar to what has been reported in other trauma populations, although MRSA was equally likely to be identified in early- and late-onset pneumonia. Our results suggest that risk factors other than duration of hospitalization may be important considerations in the decision to initiate MRSA-active empiric therapy for pneumonia in the trauma-burn ICU.