In the study of infection and inflammatory mechanisms of the lower respiratory tract, the unknown dilution of tracheobronchial wash samples is a serious problem for interpretation of the measured concentrations of various substances. The range of dilution in a true clinical situation was investigated with the goal to determine the validity of using urea dosage in tracheobronchial wash to correct the dilution. The study samples consisted of tracheobronchial wash specimens from 7 foals with Rhodococcus equi infection. Total and differential cell counts were made and compared with clinical status and bacterial recuperation of all samples. The dilution factors of the nasal lavage specimens varied between 14.3 and 130 (median 59.7). The use of urea as a dilution mark improves the accuracy of quantifying total cell concentration in washes. These findings suggest that the most common current practice of meansuring substances in tracheobronchial wash, without correction for the dilution, may induce to false conclusions.
Rhodococcus equi; foal; tracheobronchial wash; urea; dilution factors
