JOURNAL OF CLINICAL MICROBIOLOGY, Nov. 1982, p. 968-970 Vol. 16, No. 5 0095-1137/82/110968-03$02.00/0 Copyright © 1982, American Society for Microbiology Detection of Yeasts and Filamentous Fungi in Blood Cultures During a 10-Year Period (1972 to 1981) JACQUES BILLE, LESLIE STOCKMAN, AND GLENN D. ROBERTS* Section of Clinical Microbiology, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905 Received 27 May 1982/Accepted 4 August 1982 During a 10-year period (January 1972 to December 1981), 69,066 fungal blood cultures were performed by using a biphasic brain heart infusion medium. A total of 838 fungi were recovered from 302 patients. Candida species represented 71% (595) of all positive cultures, Cryptococcus neoformans 12.6% (106), and Histo- plasma capsulatum 13.1% (110). An increase in the number of cases of funge- recovered from 302 patients. The overall recov- mia at the Mayo Clinic in 1981 and our interest in ery rate of fungi in blood cultures during this newly developed blood culture procedures period was 1.21%, with yearly variations ranging prompted us to review the fungal blood cultures between 0.75% and 2.52%. performed during the 10-year period January Table 1 lists all isolates by genus and species 1972 to December 1981. that were recovered and the number of patients We determined the recovery rate and the from whom they were recovered. Candida spp. mean recovery time offungi in the biphasic brain represented 71% of all isolates and 74.8% of all heart infusion (BHI) blood culture bottle previ- positive patients. C. albicans was the most ously described (11). Data on recovery of yeasts common member of the genus (42.5%), followed in blood are limited in the literature (4, 5, 11, 15) by C. tropicalis (17%) and C. glabrata (14%). and are scant for the filamentous fungi (6, 14). The next two most frequently recovered orga- Such data are necessary to detect changes in the nisms were C. neoformans (12.6%) and H. cap- predominant species of yeasts found in blood sulatum (13.1%). The genera Candida and Cryp- cultures and to determine their recovery time. tococcus represented 84% of all positive They may also serve as comparative values in cultures and 85% of all positive patients. the evaluation of new fungal blood culture sys- Table 2 shows the recovery time in days for tems as they are developed. yeasts and filamentous fungi in the BHI biphasic Fungal blood culture data collected from Jan- bottle. Among the Candida species, C. glabrata uary 1972 to December 1981 were reviewed for and a rare isolate of C. lusitaniae required an the recovery of yeasts and filamentous fungi. extended incubation period. Isolates of C. tropi- Blood (10 ml) was collected and inoculated into calis, C. krusei, and C. pseudotropicalis were a biphasic BHI agar-broth bottle (Diagnostics, the only yeasts recovered in less than 3 days. In Inc., St. Paul, Minn.) when fungal sepsis was contrast, the mean recovery time exceeded 14 suspected. Each bottle contained a slant of 50 ml days for isolates ofH. capsulatum and Nocardia of BHI agar (BBL Microbiology Systems, Cock- asteroides. eysville, Md.) overlaid with 60 ml of BHI broth Figure 1 shows the number of patients with (Difco Laboratories, Detroit, Mich.). After in- fungemia and their etiological agents by genus oculation, the cultures were permanently vented and species during three successive periods dur- with a sterile cotton-plugged needle and incubat- ing this study. Although the number of cases of ed in an upright position for 30 days at 30°C. C. albicans and C. parapsilosis fungemia did not Cultures were examined daily for visual evi- vary by year, the number of patients with C. dence of growth, and each examination was tropicalis fungemia increased progressively. The followed by a gentle washing of the biphasic number of patients with C. glabrata fungemia BHI agar surface with the blood-broth mixture, increased abruptly during the last 2 years at our allowing a daily subculture onto the slant. Fungi institution. and Nocardia isolates recovered from blood Although the recovery of fungi from blood is cultures were further identified by using conven- not always a reliable index of disseminated or tional procedures (9). invasive disease, fungal blood cultures remain During the 10-year study period, the results of the standard method for the detection of funge- 69,066 fungal blood cultures were reviewed. A mia (12). Fungemia is a relatively uncommon total of 838 yeasts or filamentous fungi were event; however, the overall blood culture posi- 968 VOL. 16, 1982 NOTES 969 TABLE 1. Number of cultures and patients positive study evaluated a commercially available BHI for fungi in the biphasic BHI fungal blood culture biphasic bottle that contained sodium polyaneth- medium during a 10-year period, 1972-1981 olsulfonate and carbon dioxide, unlike the sys- that we previously described (11). Cultures Organism No. of No. of tem Organism ~~~positive ptet were incubated at 25 to 27°C, not at the recom- cultures patients mended incubation temperature of 30°C. Recov- Candida albicans 263 101 ery times reported for the BHI medium were Candida tropicalis 100 36 greatly extended and did not agree with those Candida glabrata 84 34 reported here or those previously reported (11). Cryptococcus neoformans 106 30 The only valid comparative data regarding the Candida parapsilosis 76 29 detection time included in the study were de- Histoplasma capsulatum 110 26 Candida tropicalis 59 20 rived from eight cultures from five patients. We (sucrose-negative variant) feel that these scant data do not support the Nocardia asteroidesa 6 5 strong conclusions reached by the authors. Candida krusei 3 3 In our experience, 88% of all yeasts were Coccidioides immitis 5 1 detected during the first week of incubation, and Rhodotorula spp. 3 2 39 and 50%o of the isolates of C. glabrata and C. Candida pseudotropicalis 3 1 lusitaniae, respectively, were detected during Candida lusitaniae 6 1 the second week. N. asteroides and the filamen- Candida spp. 1 1 tous fungi required more than 2 weeks of incuba- Saccharomyces spp. 2 1 Sporothrix schenckii 1 1 tion until detection. Due to the extended incuba- Fusarium spp. 1 1 tion period of the latter, it is recommended that Othersb 9 9 cultures be kept for 30 days before being dis- carded as negative. a Nocardia asteroides is considered to be a branch- Changes iin the distribution of predominant ing, partially acid-fast bacterium; however, it is com- of Candida in fungemia during monly recovered on media after extended incubation. species involved b Considered as contaminants: Cryptococcus lau- recent years have been recognized (7, 13), par- rentii (2 cultures/2 patients), Aspergillus species (3/3), ticularly the emergence of C. tropicalis as a Streptomyces (2/2), Ustilago (1/1), and Chaetomium significant cause of disseminated fungal disease. (1/1). We observed the same increase in the number of cases offungemia due to C. tropicalis during the period of this study. The frequency of cases of tivity rate of 1.21% at our institution is slightly higher than those reported in two large cancer TABLE 2. Recovery times of fungi in the biphasic hospitals (0.8 to 1.0o [4, 5]) and three times as BHI fungal blood culture medium Recovery time high as the rate of positivity found in a university Organism (days) hospital by using a radiometric method of detec- Mean 50%o" 95%b Range tion These differences reflect a selec- (8). might Candida albicans 3.5 3 8 1-13 tion of patients at different institutions as well as Candida tropicalis 2.9 3 5 1-9 variation in the methods of detection. Special Candida glabrata 8.3 7 19 2-28 conditions of incubation, particularly venting of Cryptococcus neoformans 4.8 3 11 1-21 the blood culture bottle, allow for better recov- Candida parapsilosis 4.3 4 8 1-12 ery of yeasts (1-3, 10). The use of a biphasic Histoplasma capsulatumc 19.5 19 35 3-39 BHI vented bottle not only improved the recov- Candida tropicalis 2.3 2 4 1-5 ery rate of yeasts and fungi in blood, but it also (sucrose-negative variant) shortened the time of detection when compared Nocardia spp. 15.8 12 7-23 broth bottle J. Bille et Candida krusei 2.8 3 1-4 with a standard (5; al., Coccidioides immitis 12.4 11 8-22 submitted for publication). A shortened detec- Rhodotorula spp. 6.7 4-9 tion time is very important for better patient Candida pseudotropicalis 2.3 2-3 management, since fungemia is often detected Candida lusitaniae 8.7 7 3-14 late in the course of the disease or after death. Saccharomyces spp. 3.0 3 Rapid detection time of yeasts in blood under Sporothrix schenckii 8.0 8 a radiometric procedure (Johnston Labora- Fusarium spp. 3.0 3 was tories, Inc., Cockeysville, Md.) reported a Indicates 50%to of the positive blood cultures de- recently by Hopfer et al. (4). Prevost and Ban- tected before that time. nister (8) also reported data comparing the radio- I Indicates 95% of the positive blood cultures de- metric method with a biphasic BHI medium and tected before that time. concluded that the latter was unsatisfactory for c Cultures were incubated for an additional 2 weeks the detection of yeasts in blood. However, this since past cultures were positive for H. capsulatum. 970 NOTES J. CLIN. MICROBIOL. 5 Candida albicans oploplp - - - - -- -1- a Candida tropicalis -.i Candida glabrata I Candida parapsilosis [] 1980 -,Si 13 1975 -79 Cryptococcus neoformans N 1972 -74 1 Histoplasma capsulatum 11 -1 I I I I I 0 2 4 6 8 10 12 Number of cases/year FIG.