Comparison of bacteriology and cytology of tracheal fluid samples collected by percutaneous transtracheal aspiration or via an endoscope using a plugged, guarded catheter.

This research paper compares two methods of collecting tracheal fluid samples in horses – percutaneous transtracheal aspiration (PTA) and a telescoping, plugged catheter (TPC) – in terms of their bacteriological and cytological output. It found no difference between the methods in terms of their cellular composition but noticed a higher incidence of oropharyngeal contamination in samples with greater quantities of squamous epithelial cells.

Research Objectives and Methodology

• The objective of this research was to compare the cytological and bacteriological output of tracheal fluid samples collected by evaluation of PTA and TPC techniques.
• The study was performed on 9 healthy Standardbred geldings, with the order of procedures randomized. After 3 weeks, the methods were reversed.
• The presence of oropharyngeal contamination, which could indicate inaccuracies in testing and diagnosis, was determined through quantitative bacteriology and quantification of squamous epithelial cells (SEC) per milliliter sample.

Findings

• The research found no significant difference between the two sample collection techniques in terms of the relative numbers of macrophages, haemosiderophages, giant cells, neutrophils, lymphocytes and eosinophils, as they remained similar in both methods.
• The number of SEC/ml was discovered to be higher in samples with more colony-forming units/ml, suggesting that quantification of SEC can be an indicative factor for the extent of oropharyngeal contamination.
• It was observed that 15 out of the 18 TPC samples were free of contamination, implying that TPC technique can be effective in providing adequate samples for bacteriology.

Implications

• The findings may indicate that tracheoscopy, although commonly used and practiced, can lead to oropharyngeal contamination of the trachea, thereby potentially affecting the accuracy of the result.
• However, the study also found that such contamination does not affect the results for TPC sample collection.
• This result can prove to be valuable in deciding the more effective and accurate method for collecting tracheal fluid samples, aiding physicians in achieving more accurate diagnoses and treatments.