Semiquantitative technique for estimating Pneumocystis carinii burden in the lung.

We developed a technique to estimate the amount of Pneumocystis carinii found in bronchoalveolar lavage fluid. P. carinii associated with 500 nucleated cells in the bronchoalveolar lavage fluid had little between-observer and within-observer variation. Varying the technique of the lavage did not change the amount of P. carinii recovered. This technique was used in patients treated for P. carinii pneumonia. Those patients who did not respond to treatment had more P. carinii in their bronchoalveolar lavage fluid than those who responded.