The Effect of Tracheal Fluid Culture Sampling Method and Culture Results on Antibiotic Use in Neonates

Objective As part of quality improvement effort to decrease antibiotic use for presumed pneumonia (PNA) in our neonatal intensive care unit, we introduced minibronchoalveolar lavage (mBAL) to obtain culture specimens. We evaluated the effect of tracheal sampling method and culture results on antibiotic use. Methods We performed a retrospective review of culture results of samples obtained by tracheal aspirates (TAs) and mBAL between January 2017 and April 2018. Noting the time cultures were obtained, we reviewed the records to determine if the patients met the Center for Disease Control and Prevention (CDC) criteria for PNA and evaluated culture results and antibiotic treatment practice. Fisher's exact and Mann-Whitney's tests when appropriate were used for the analysis. Results Thirty-five (35) mBAL (on 21 patients) and 42 TAs (on 39 patients) were done prior to antibiotic therapy. The tests were done at similar median day of life in both groups (mBAL 55 days and TA 62 days). The frequencies of positive culture were similar in both groups (mBAL 60% and TA 57%). At the time of obtaining the sample, more mBAL patients met the CDC criteria for PNA (mBAL 54% and TA 26%). Antibiotic days and duration of antibiotic treatment were significantly higher in the mBAL group compared with the TA group. In patient with no clinical PNA, antibiotic days were significantly higher in those with positive cultures (which more likely reflect colonizing microbes) than those with negative cultures and were also higher in the mBAL group than in the TA group. There was a significant increase in the frequency of positive cultures in patients with longer hospital stay. Conclusion Our results show that tracheal cultures on sick neonates with no clinical PNA and with long hospital stay might contribute to unnecessary antibiotic use regardless of the tracheal sampling method.