Response

Abstract

Response: We thank the authors for their comments, which we addressed in the discussion of our article. We found no evidence of a Nocardia outbreak to explain the increase in nocardial infections, which occurred over a period of several years at multiple locations [1Molina A Winston DJ Pan D Schiller GJ Increased incidence of nocardial infections in an era of atovaquone prophylaxis in allogeneic hematopoietic stem cell transplant recipients.Biol Blood Marrow Transplant. August 2018; Abstract Full Text Full Text PDF Scopus (20) Google Scholar]. Furthermore, because the lung is the most common site of nocardial infection in both sporadic cases and in reported outbreaks, the occurrence of only pulmonary cases in our report does not necessarily imply a localized outbreak. We also began seeing more cases of nocardiosis before the change in culture methods for isolation of Nocardia species. Finally, we acknowledge in our article on several occasions that the degree to which trimethoprim-sulfamethoxazole (TMP-SMX) protects against nocardial infection after allogeneic hematopoietic stem cell transplantation (HSCT) is not entirely clear. Nonetheless, similar to our experience, most patients in previous studies of nocardiosis after HSCT were also not taking TMP-SMX prophylaxis [2Van Burik JA Hackman RC Nadeem SQ et al.Nocardiosis after bone marrow transplantation: a retrospective study.Clin Infect Dis. 1997; 24: 1154-1160Crossref PubMed Scopus (108) Google Scholar, 3Choucino C Goodman SA Greer JP et al.Nocardial infections in bone marrow transplant recipients.Clin Infect Dis. 1996; 26: 1012-1019Crossref Scopus (88) Google Scholar, 4Daly AS Mcgeer A Lipton JH Systemic nocardiosis following allogeneic bone marrow transplantation.Transpl Infect Dis. 2003; 5: 16-20Crossref PubMed Scopus (48) Google Scholar, 5Shannon K Pasikhova Y Ibekweh Q Ludlow S Baluch A Nocardiosis following hematopoietic stem cell transplantation.Transpl infect Dis. 2016; 18: 169-175Crossref PubMed Scopus (27) Google Scholar, 6Lebeauy D Morelon E Suarez F et al.Nocardiosis in transplant recipients.Eur J Clin Microbial Infect Dis. 2014; 33: 689-702Crossref PubMed Scopus (74) Google Scholar]. Both the dose of TMP-SMX and the duration of prophylaxis may determine the effectiveness of TMP-SMX for prevention of nocardiosis. The 2 patients in our article who developed nocardiosis on TMP-SMX were either on a low dose given only 3 times weekly or had received TMP-SMX prophylaxis for only 2 weeks. Breakthrough nocardial infections reported by others have also occurred primarily on low doses of TMP-SMX [2Van Burik JA Hackman RC Nadeem SQ et al.Nocardiosis after bone marrow transplantation: a retrospective study.Clin Infect Dis. 1997; 24: 1154-1160Crossref PubMed Scopus (108) Google Scholar-6Lebeauy D Morelon E Suarez F et al.Nocardiosis in transplant recipients.Eur J Clin Microbial Infect Dis. 2014; 33: 689-702Crossref PubMed Scopus (74) Google Scholar]. In contrast, the high doses of TMP-SMX used at UCLA for Pneumocystis jiroveci pneumonia (PJP) prophylaxis, which were associated with only 1 case of nocardiosis over 11years from 2000 to 2012, may be more effective for prevention of nocardiosis and PJP than atovaquone prophylaxis. Financial disclosure: The authors have nothing to disclose. Conflict of interest statement: There are no conflicts of interest to report.