Methods: Of 857 BAL specimens obtained from 9/2014-5/2015, 55 (6.5%) were from pts undergoing BAL for suspected IPA. Clinical, microbiological & radiological data were collected on these 55 pts. Two groups based on IPA risk factors were compared: Heme-27 pts (12 hematological malignancy pts, 15 stem cell transplant pts) & non-Heme-28 pts (10 solid organ transplants (SOT) & 18 other non-SOT). Proven/probable/possible IPA was defined by EORCT/MSG criteria, except that BAL GM was excluded as a diagnostic criterion. GM & LFA were performed on BAL by investigators blinded to the Dx of IPA.
Results: By EORTC/MSG criteria, 4 pts (7%) were probable IPA (2 Heme/2 non-Heme); 12 pts (22%) were possible IPA (8 Heme/4 non-Heme); and 39 pts (71%) were non-IPA (17 Heme/22 non-Heme). 4 pts had (+) GM (1 non-Heme, probable IPA; 1 Heme, possible IPA/1 non-Heme, possible IPA; 1 non-Heme, non-IPA). 1 pt had a weak (+) LFA (non-Heme, non-IPA). Anti-mold prophylaxis was used in 18 pts (33%); 15 (56%) of Heme pts compared to 3 (11%) non-Heme pts. Of the 15 Heme pts on prophylaxis, 6 were possible IPA and 9 were non-IPA. In these 15 heme pts, LFA was (-) & GM was (+) in only 1 with possible IPA. Overall, BAL GM & LFA had comparable specificity and negative predictive value (97.4%, 92.7% vs. 97.4%, 90.5%, respectively).
Conclusion: Anti-mold prophylaxis has markedly reduced the incidence of IPA among Heme pts at our medical center. Our study shows that diagnostic performance, especially the negative predictive value, of GM and LFA on BAL fluid is similar. In the setting of low incidence of IPA, antigen tests, such as GM and LFA in BAL fluid, are most useful in helping to exclude the diagnosis of IPA. LFA could become the preferred assay because it is a rapid, inexpensive, easily performed test.
S. Hillman, None
M. Miceli, None