Infection What Is the Clinical Significance of Positive Blood

Infection What is the clinical signiﬁcance of positive blood cultures with Aspergillus sp in hematopoietic stem cell transplant recipients? A 23 year experience

E Simoneau1, M Kelly1, AC Labbe1, J Roy2 and M Laverdie` re1

1Department of Microbiology-Infectious Diseases, Hoˆpital Maisonneuve-Rosemont, Quebec, Canada; and 2Department of Hematology, Hoˆpital Maisonneuve-Rosemont, Quebec, Canada

Summary: underlying predisposing condition to invasive aspergillosis.3 To our knowledge, no study has yet examined the Hematopoietic stem cell (HSC) transplantation is the significance of positive blood cultures with Aspergillus sp most frequent underlying predisposing condition to in this very high-risk population of patients. We report a invasive aspergillosis. However, the significance of posi- 23-year single-center retrospective study of positive blood tive blood culture with Aspergillus sp in this particular cultures for Aspergillus sp documented in HSC transplant population remains uncertain. We retrospectively re- recipients. viewed all blood cultures performed in 1453 patients who received HSC transplant at our institution between 1980 and 2002. We identified 19 patients with positive blood Patients and methods cultures with Aspergillus sp. Only one of these patients had clinical, histologic or microbiologic evidence of Blood culture records of all patients who underwent an invasive aspergillosis. Thus, even in a population at HSC transplantation at Hoˆ pital Maisonneuve-Rosemont highest risk for invasive aspergillosis, positive blood (HMR) between April 1980 and December 2002 were cultures with Aspergillus sp remain unusual, and cannot reviewed. Over this period, three different blood culture be readily associated with invasive aspergillosis. A case by systems have been sequentially used in our microbiology case assessment by treating physicians of the clinical and laboratory: a conventional broth manual system from radiologic parameters should be systematically made to 1980 to 1985, a lysis centrifugation blood culture system establish the significance of aspergillemia. Single bottle (Isolatort system) from 1985 to 1996, and an automated positivity, obtained with the lysis-centrifugation blood blood culture system (BacT/Alertt system) thereafter. culture system, is a common indicator of pseudoaspergil- Medical records of recipients with Aspergillus sp positive lemia. blood cultures were reviewed to determine the clinical Bone Marrow Transplantation (2005) 35, 303–306. significance of these positive blood cultures. Aspergillus sp doi:10.1038/sj.bmt.1704793 fungemia was classified as definite, probable or pseudo- Published online 6 December 2004 fungemia according to previously proposed criteria.4 Keywords: Aspergillus; hematopoietic stem cell (HSC) Definite Aspergillus sp fungemia was defined as the transplantation; bloodstream infections; aspergillemia presence of Aspergillus sp in blood plus histologic or microbiologic evidence of Aspergillus sp in infected tissue; probable aspergillemia was defined as the presence of The significance of positive blood cultures with Aspergillus Aspergillus sp in blood with clinical signs and symptoms sp varies according to the patient population. In a single- compatible with disseminated aspergillosis, but no histo- cancer center study, positive blood cultures with Aspergillus pathologic evidence of invasive aspergillosis and pseudo- sp represented pseudofungemia in all 12 patients with solid fungemia was defined as the presence of Aspergillus sp in tumors, whereas definite or probable aspergillemia was blood without compatible signs and symptoms, imaging, observed in 12 of 24 patients with hematological malig- culture, or histologic evidence of invasive aspergillosis. nancies.1 In patients with deep-seated pulmonary aspergillosis, true aspergillemia was observed in 10.1% of 89 patients.2 HSC transplantation is the most important Results

From April 1980 to December 2002, 1453 patients were transplanted at HMR. A total of 939 different episodes of Correspondence: Dr M Laverdie` re, Department of Microbiology- bloodstream infections in 525 (36%) recipients were Infectious Diseases, Hoˆ pital Maisonneuve-Rosemont, 5415 Boul de documented. Of these 525 patients, 377 were allogeneic L’Assomption Montreal, Quebec, Canada H1T 2M4; E-mail: [email protected] and 148 autologous transplant. Aspergillemia was observed Received 14 June 2004; accepted 11 October 2004 23 times in 21 patients. Patients 1 and 10 each had two Published online 6 December 2004 separate episodes at 3- and 2-month intervals, respectively oeMro Transplantation Marrow Bone 304

Table 1 Clinical characteristics and signiﬁcance of positive blood cultures with Aspergillus sp in 19 HSCT recipients

Patient Date Age Sex Underlying HSCT Neutropenia GVHD Duration of Days after Fever Anti- Evidence of Species no (months/ (years) haematologic type on day of and/or HD neutropenia HSCT at at time of aspergillusantifungal clinical years) diagnosis positive steroids following time of aspergillemia at time of aspergillosis blood culture HSCT (days) aspergillemia sampling inﬁac faprilmai STrecipients HSCT in aspergillemia of Signiﬁcance 1a 06/88 5 F ALL Allo NA Yes NA 10 NA No No A fumigatus 1b 09/88 5 F ALL Allo NA Yes NA 91 NA No No A fumigatus 2 03/89 16 M ALL Allo No No 21 55 No No No A niger 3 05/89 18 M ALL Auto No Yes 28 29 No No No Aspergillus sp 4 05/90 39 F MM Allo Yes Yes 25 4 Yes No No A fumigatus 5 12/90 49 M NHL Auto Yes Yes 13 4 No No No Aspergillus sp 6 12/91 42 F NHL Auto Yes Yes 105 10 Yes Yes No A fumigatus 7 06/92 39 F CML Allo NA Yes NA 77 NA Yes No A fumigatus 8 08/92 32 F AML Allo Yes Yes 19 6 Yes No No Aspergillus sp Simoneau E 9 09/92 30 F ALL Allo Yes No 20 4 No No No A fumigatus 10a 10/92 3 F AA Auto No Yes NA 41 No No No A fumigatus

10b 12/92 3 F AA Auto No Yes NA 101 No No No A fumigatus al et 11 11/92 7 M IMM Allo No Yes 14 54 No No No Aspergillus sp 12 11/92 47 M NHL Auto No Yes 26 31 No Yes No A niger 13 04/94 58 M NHL Auto Yes Yes 21 4 Yes No No A fumigatus 14 05/94 12 F CML Allo Yes Yes 28 11 No No No A fumigatus 15 03/95 3 F MDS Allo No Yes 24 135 No No No Aspergillus sp 16 03/95 3 F AA Allo Yes Yes 32 13 No Yes No Aspergillus sp 17 06/95 36 F CML Allo No Yes 16 537 Yes No No A fumigatus 18 09/96 52 M CML Allo No Yes 19 101 Yes Yes Yes Aspergillus sp 19 10/97 41 M CML Allo Yes Yes 28 29 No Yes No A fumigatus

HSCT ¼ hematopoietic stem cell transplantation; AA ¼ aplastic anemia; ALL ¼ acute lymphocytic leukemia; AML ¼ acute myeloblastic leukemia; MM ¼ multiple myeloma; CML ¼ chronic myelogenic leukemia; NHL ¼ non-Hodgkin’s lymphoma; MDS ¼ myelodysplasic syndrome; IMM ¼ primary immune deficiency; Allo ¼ allogeneic; Auto ¼ autologous; GVHD ¼ graft versus host disease; HD steroids ¼ High-dose steroids; NA: not available. Significance of aspergillemia in HSCT recipients E Simoneau et al 305 (Table 1). Median time between the HSC transplantation were processed in a laminar air-flow facility, an airborne and positive blood culture with Aspergillus sp was 29 days contamination likely could not be completely avoided. (range 4–537 days). Aspergillus sp was recovered from a Automated blood culture systems are now commonly used single bottle collected in different sets of blood cultures for in hospital microbiology laboratories. The adequacy of all patients. All aspergillemic episodes were observed these systems to recover fungal pathogens from blood during the period when the lysis centrifugation blood cultures has been questioned, and the superiority of the culture system was used. Aspergillus fumigatus was lysis–centrifugation blood culture system has been under- identified in 11 patients, Aspergillus niger in two patients lined.5 However, routine procurement of blood cultures and nonspeciated Aspergillus in eight patients. Medical with the latter system in febrile neutropenic patients with records of 19 recipients were available for review. Six acute leukemia has shown no advantage over an automated patients were on Amphotericin B prophylaxis or treatment system to detect fungal and bacterial blood pathogens, and at the time of their blood sampling (Table 1). No other has been associated with high degree of contamination.6 anti-aspergillus antifungal drugs were used in any of our Large studies have been conducted with modern automated patients. Only two patients (patient 17 and 18) died within blood culture systems, but recovery of Aspergillus sp is not 30 days following their aspergillemia. Patient 17 had a documented.7–10 We have experimentally inoculated as little broncho-pulmonary-obliterans pneumonitis and an intest- as one to 10 conidia into blood culture bottles of our inal graft-versus-host-disease (GVHD) with severe electro- current colorimetric automated blood culture system lytic disorders. She died 10 days after her single positive (BacT/Alertt), and systematically detected growth after blood culture bottle with Aspergillus. A post-mortem only 24 h of incubation, hence establishing the ability of the examination revealed diffuse multiorgan lymphomatous system to support and detect the growth of Aspergillus sp. infiltrations with no signs of aspergillosis. Patient 18 had Vascular invasion characterizes invasive aspergillosis. compatible pulmonary infiltrates with clinical signs and Aspergillus hyphae are endocytosed by the blood vessel symptoms and evolution suggestive of a probable invasive endothelial cells causing progressive endothelial cell injury aspergillosis. Despite systemic antifungal therapy, this and thrombosis. Vascular endothelial cells exposed in vitro patient suffering from chronic GVHD died 10 days later. to killed Aspergillus hyphae continue to cause cell injury An autopsy was not granted. Of the remaining 17 patients, and invasion.11 It is likely that the viability of the only four received Amphotericin B, mostly for persisting endocytosed Aspergillus hyphae is considerably impaired, febrile neutropenia, during 5–19 days following the positive which therefore reduces the potential to recover them blood culture with Aspergillus. These patients along with through blood cultures. those untreated patients, had neither clinical nor radi- In conclusion, even in the population of patients with the ological signs and symptoms compatible with invasive highest risk for invasive aspergillosis, that is, HSC aspergillosis, and therefore their positive blood cultures transplant recipients, positive blood cultures with Aspergil- were categorized as pseudofungemia. lus sp are rare, usually represent pseudofungemia and cannot be readily associated with invasive aspergillosis. Clinical and radiologic assessment of the patients’condi- Discussion tions, number of positive blood cultures and awareness of the type of blood culture system used in the institution In our homogeneous high-risk population of HSC trans- should be systematically considered by treating physicians plant recipients, our results confirm that positive blood in order to establish the clinical significance of aspergille- cultures with Aspergillus sp are rare and usually clinically mia in HSC recipients. Single bottle positivity, obtained insignificant, despite the propensity of Aspergillus to invade with the lysis–centrifugation blood culture system is a the vascular compartment in these immunocompromised common indicator of pseudoaspergillemia. hosts. Aspergillus fungemia represented 17% of all fungemias (23 out of 131 cases) observed in our hospital’s HSC recipient population during this study’s 23-year surveillance Acknowledgements period. By comparison, in a similar single-center study conducted over a 17-year period, Aspergillus fungemia We thank Catherine Guilbault and Miche` le Joseph for their help accounted for 4% of all fungemias. These, however, were in retrieving the patients’ data. compiled only in non-HSC transplant patients with hematological malignancies.2 Only one of our 19 evaluated patients with positive blood References cultures with Aspergillus sp was likely a true fungemia. During our 23-year study period, the incidence of invasive 1 Kontoyiannis DP, Sumoza D, Tarrand J et al. Significance of aspergillosis in our HSC recipients remained stable, ranging aspergillemia in patients with cancer: a 10-year study. Clin from 3.8 to 5.4%. Interestingly, all our aspergillemia Infect Dis 2000; 31: 188–189. occurred during the 11-year period when a lysis–centrifuga- 2 Girmenia C, Nucci M, Martino P. Clinical significance of Aspergillus fungaemia in patients with haematological malignan- tion blood culture system was in use in our microbiology cies and invasive aspergillosis. Br J Haematol 2001; 114: 93–98. laboratory. During those years, over 23 000 blood cultures 3 Patterson TF, Kirkpatrick WR, White M et al. Invasive were processed with the lysis–centrifugation system. Of aspergillosis. Disease spectrum, treatment practices, and out- these, 0.2% grew a filamentous fungus, most commonly an comes. I3 Aspergillus Study Group. Medicine (Baltimore) Aspergillus sp. Despite the fact that all those blood cultures 2000; 79: 250–260.

Bone Marrow Transplantation Signiﬁcance of aspergillemia in HSCT recipients E Simoneau et al 306 4 Duthie R, Denning DW. Aspergillus fungemia: report of two 8 Fuller DD, Davis Jr TE, Denys GA et al. Evaluation of cases and review. Clin Infect Dis 1995; 20: 598–605. BACTEC MYCO/F Lytic medium for recovery of mycobac- 5 Reimer LG, Wilson ML, Weinstein MP. Update on detection teria, fungi, and bacteria from blood. J Clin Microbiol 2001; of bacteremia and fungemia. Clin Microbiol Rev 1997; 10: 39: 2933–2936. 444–465. 9 Ziegler R, Johnscher I, Martus P et al. Controlled clinical 6 Madani TA, Kabani A, Hoban D et al. Value of routine laboratory comparison of two supplemented aerobic and procurement of Isolator in addition to BacT/Alert blood anaerobic media used in automated blood culture systems to cultures in febrile neutropenic patients with acute myeloid detect bloodstream infections. J Clin Microbiol 1998; 36: leukemia. Can J Infect Dis 1998; 9: 287–293. 657–661. 7 Vetter E, Torgerson C, Feuker A et al. Comparison of the 10 Hellinger WC, Cawley JJ, Alvarez S et al. Clinical comparison BACTEC MYCO/F Lytic bottle to the isolator tube, of the isolator and BacT/Alert aerobic blood culture systems. BACTEC Plus Aerobic F/bottle, and BACTEC Anaerobic J Clin Microbiol 1995; 33: 1787–1790. Lytic/10 bottle and comparison of the BACTEC Plus Aerobic 11 Lopes-Bezerra LM, Filler SG. Interactions of Aspergillus F/bottle to the Isolator tube for recovery of bacteria, fumigatus with endothelial cells: internalization, injury and mycobacteria, and fungi from blood. J Clin Microbiol 2001; stimulation of tissue factor activity. Blood 2004; 103: 39: 4380–4386. 2143–2149.

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