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Journal of Clinical Microbiology, October 2006, p. 3551-3556, Vol. 44, No. 10
0095-1137/06/$08.00+0 doi:10.1128/JCM.00865-06
Copyright © 2006, American Society for Microbiology. All Rights Reserved.
University of Iowa College of Medicine, Iowa City, Iowa,1 Hospital Militar Central, Bogotá, Columbia,2 Royal Free Hospital, London, United Kingdom,3 ANTSZ BAZ Megyei Intezete, Miscolc, Hungary,4 National Taiwan University Hospital, Taipei, Taiwan,5 Giles Scientific, Inc., Santa Barbara, California6
Received 24 April 2006/ Returned for modification 31 May 2006/ Accepted 31 July 2006
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2 µg/ml (96%; MIC50/MIC90, 0.5/1.0 µg/ml). C. guilliermondii, a species that exhibits reduced susceptibility to fluconazole, is the sixth most frequently isolated Candida species from this large survey and may be an emerging pathogen in Latin America. |
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Those reports suggest that although rare, C. guilliermondii may exhibit decreased susceptibility to several different classes of antifungal agents, may be transmitted from patient to patient in the hospital setting, and may be associated with the presence of an intravascular foreign body. Recent in vitro survey data confirm the decreased susceptibility of this species to fluconazole, although the numbers of isolates tested were generally small (1, 10, 12, 26, 27). Likewise, the MICs of caspofungin, anidulafungin, and micafungin have been observed to be 2- to 16-fold higher for C. guilliermondii than for other species of Candida, with the exception of Candida parapsilosis (4, 10, 15, 18).
Aside from these limited observations, there is little information regarding the epidemiology, frequency of occurrence, and antifungal susceptibility profile of this rare species of Candida (4, 12). Given the fact that the data available suggest the potential for decreased susceptibility of C. guilliermondii to polyenes, azoles, flucytosine, and the echinocandins, it seems prudent to gather additional information regarding this opportunistic fungal pathogen. In the current study, we use the extensive database provided by the ARTEMIS DISK Antifungal Surveillance Program (16) to describe the geographic and temporal trends in the isolation of C. guilliermondii from clinical specimens collected from 127 medical centers between 1997 and 2003, the types of specimens and clinical services in which C. guilliermondii infections are recognized, and the in vitro susceptibilities of 1,029 clinical isolates, including 307 bloodstream infection (BSI) isolates, of this species to fluconazole and voriconazole as determined by standardized disk diffusion testing. This report will serve as the largest study of C. guilliermondii isolates to date.
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Data for C. guilliermondii were stratified by year of isolation, geographic region, clinical service (hospital location), and specimen type. Candida spp. considered by the local-site investigator to be colonizers, that is, not associated with an obvious pathology, were excluded, as were duplicate isolates (the same species and the same susceptible-resistant biotype profile within any 7-day period). Identification of isolates was performed in accordance with each site's routine methods.
Susceptibility test methods. Disk diffusion testing of fluconazole and voriconazole was performed as described previously (16) and in accordance with Clinical and Laboratory Standards Institute (CLSI) (formerly NCCLS) document M44-A (9). Plates (150-mm diameter) containing Mueller-Hinton agar (obtained locally at all sites) supplemented with 2% glucose and 0.5 µg of methylene blue per ml at a depth of 4.0 mm were used. The agar surface was inoculated by using a swab dipped in a cell suspension adjusted to the turbidity of a 0.5 McFarland standard. Fluconazole (25-µg) and voriconazole (1-µg) disks (Becton Dickinson, Sparks, Md.) were placed onto the surfaces of the plates, and the plates were incubated in air at 35 to 37°C and read at 18 to 24 h. Zone diameter endpoints were read at 80% growth inhibition by using the BIOMIC image analysis plate reader system (version 5.9; Giles Scientific, Santa Barbara, Calif.) (5, 13, 16, 17).
MICs of caspofungin were determined by broth microdilution (BMD) as described previously (18). All isolates were tested in RPMI broth with 24 h of incubation and a prominent reduction in growth relative to control (MIC-2) endpoint criteria.
The interpretive criteria for the fluconazole and voriconazole disk diffusion tests were those of the CLSI (9, 19, 20) and are as follows: susceptible (S), zone diameters of
19 mm (fluconazole) and
17 mm (voriconazole); susceptible-dose dependent (SDD), zone diameters of 15 to 18 mm (fluconazole) and 14 to 16 mm (voriconazole); resistant (R), zone diameters of
14 mm (fluconazole) and
13 mm (voriconazole). The corresponding MIC breakpoints (8, 19, 20) are as follows: S, MIC of
8 µg/ml(fluconazole) and
1 µg/ml (voriconazole); SDD, MIC of 16 to 32 µg/ml (fluconazole) and 2 µg/ml (voriconazole); R, MIC of
64 µg/ml (fluconazole) and
4 µg/ml (voriconazole).
QC. Quality control (QC) was performed in accordance with CLSI document M44-A (9) by using Candida albicans ATCC 90029 and C. parapsilosis ATCC 22019. A total of 5,865 and 5,484 QC results were obtained for fluconazole and voriconazole, respectively, more than 99% of which were within the acceptable limits. External quality assurance was performed by testing more than 2,900 isolates from blood and NSBF against both fluconazole and voriconazole by ARTEMIS participating laboratories and by the central reference laboratory (13, 17). Excellent agreement was seen between participating and reference laboratories, ensuring the accuracy of the ARTEMIS data.
Analysis of results. All disk zone diameters were read by electronic image analysis and interpreted and recorded with a BIOMIC Plate Reader system (Giles Scientific Inc.). Test results were sent by e-mail to Giles Scientific for analysis. The zone diameter susceptibility category (S, SDD, or R), and QC test results were all recorded electronically. Patient and doctor names, duplicate test results (the same patient, the same species, and same biotype results), and uncontrolled results were automatically eliminated by the BIOMIC system prior to analysis.
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Data on the various sites that contributed isolate results to the study were available for the time period of 2001 through 2003 (Table 1). C. guilliermondii represented 1.4% of the 75,761 isolates collected during this time period and was most common in the Latin American region (Table 1), accounting for 3.7% of the isolates from the region.
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TABLE 1. Variation in frequency of Candida guilliermondii by geographic regiona
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TABLE 2. Geographic variation in susceptibility of Candida guilliermondii to fluconazole and voriconazole
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Trends in resistance to fluconazole and voriconazole among C. guilliermondii isolates over time. There was no evidence of increasing resistance to the azoles among C. guilliermondii isolates tested between 2001 and 2003. Resistance to fluconazole ranged from 11.7% in 2001 to 8.1% in 2003, and resistance to voriconazole ranged from 4.2% (2001) to 5.0% (2003) (data not shown).
Variation in the frequency of isolation and antifungal susceptibility profile of C. guilliermondii by clinical service. The clinical services reporting the isolation of C. guilliermondii from patient specimens included the hematology-oncology service, medical and surgical services, intensive care units (medical, surgical, and neonatal), the dermatology service, the urology service, and the outpatient service (Table 3). Those strains from services with only a few isolates and those for which a clinical service was not specified were included in the category "other, not otherwise specified" (NOS).
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TABLE 3. Susceptibility of Candida guilliermondii to fluconazole and voriconazole by clinical service
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Variation in the frequency of isolation and antifungal susceptibility profile of C. guilliermondii by clinical specimen type. The major specimen types yielding C. guilliermondii as a putative pathogen included blood, NSBF; urine, respiratory, skin, soft tissue, and genital specimens (Table 4). Those isolates from uncommon specimen types and those for which a specimen type was not recorded were grouped under the category "miscellaneous (Misc.), NOS."
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TABLE 4. Susceptibility of Candida guilliermondii to fluconazole and voriconazole by specimen type
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Activity of caspofungin against bloodstream isolates of C. guilliermondii.
Previously, we and others have shown that echinocandin MICs are consistently higher for C. guilliermondii and C. parapsilosis than for C. albicans when tested by BMD methods (10, 15, 18). When tested against caspofungin using the recently optimized BMD method (14, 18), 96% of the 132 bloodstream isolates of C. guilliermondii were inhibited by
2 µg/ml, a concentration that is exceeded throughout the dosing interval following the administration of caspofungin at standard doses (24, 28). Limited clinical data suggest that this species may respond to treatment with caspofungin (7).
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Prior to this survey, there was very little known about the activity of voriconazole against this species. In a large U.S. survey of 2,000 BSI isolates of Candida, Ostrosky-Zeichner et al. (10) found only nine isolates of C. guilliermondii and reported a median MIC of voriconazole of 0.06 µg/ml (range, 0.03 to 0.13 µg/ml). A previous report from our laboratory demonstrated that 96.7% of 92 BSI isolates were susceptible to voriconazole at
1 µg/ml (16). Likewise, Girmenia et al. (4) found that 20 of 21 isolates (95%) were susceptible to voriconazole (MIC range,
0.03 to 4 µg/ml). The data reported herein (Table 2) indicate an overall susceptibility to voriconazole of 91.2% among 633 isolates tested by the disk diffusion method. The difference in activity noted between fluconazole and voriconazole for this species is similar to that seen with C. glabrata (12, 16) and suggests that voriconazole may be effective against some fluconazole-resistant C. guilliermondii isolates.
Given that this species is best known as a cause of onychomycosis and superficial cutaneous infections (3), it is not surprising that we found it to be isolated fairly commonly from isolates from skin and soft tissue infections obtained from patients of the dermatology service (Tables 3 and 4). We could not confirm the increased incidence of C. guilliermondii infections among cancer patients as reported previously by Girmenia et al. (4).
Although the role of C. guilliermondii as a pathogen when isolated from nonsterile sites such as the respiratory, urinary, and genital tracts is debatable, isolates from blood and NSBF must be considered significant. Thus, it is worth noting that the single most common specimen to yield C. guilliermondii on culture was blood (Table 4). This finding lends support to the few clinical reports of invasive fungal infection due to this species, indicating that it may indeed cause significant infections (2, 4, 6, 25).
Although little geographic variation in fluconazole susceptibility was observed (Table 2), this was considerably more pronounced across the different clinical services, where the lowest activity was seen with isolates from the dermatology service (57.7% S) and the highest activity was seen with isolates from the medical service (79.9%). This could be related to the frequent use of both oral and topical azoles to treat dermatologic infections (3). The activity of voriconazole did not vary significantly by clinical service, although it should be noted that it was most active against isolates from the hematology-oncology service, where azole drug pressure is often very high.
Perhaps the most encouraging information from this survey is the finding that bloodstream isolates of C. guilliermondii remain generally susceptible to both fluconazole and voriconazole (Table 4). These findings are similar to those reported previously by Girmenia et al. (4) for Italian bloodstream isolates. Although voriconazole appears to be reliably active against isolates from other specimen types, this is not the case with fluconazole. Given the low cost and low toxicity of fluconazole, it remains a first-line treatment for most candidal infections; however, the variable activity of this agent against C. guilliermondii suggests that treatment may be best guided by accurate species identification and judicious use of antifungal susceptibility testing (11, 22, 23).
Very few isolates of C. guilliermondii have been tested against the echinocandins and other antifungal agents (10, 12, 15). Our results for caspofungin versus BSI isolates (Table 5) indicate that although MICs for this species may be elevated compared to those seen with C. albicans (18), they remain in a range that should allow infections due to this species to be treated effectively. Likewise, despite the original report of amphotericin B resistance described previously by Dick et al. (2), resistance to this agent has not been documented in subsequent studies (1, 4, 6, 10, 26). In a previous report (12), we found only 2 of 102 BSI isolates of C. guilliermondii showing possible resistance to amphotericin B (MICs of 2 and 32 µg/ml, respectively).
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TABLE 5. In vitro activity of caspofungin against 132 bloodstream isolates of Candida guilliermondiia
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The ARTEMIS DISK Surveillance Program is supported by grants from Pfizer.
We express our appreciation to all ARTEMIS participants. Participants contributing to this study included Jorge Finquelievich, Buenos Aires University, and Nora Tiraboschi, Hospital Escuela Gral., Buenos Aires, Argentina; David Ellis, Women's and Children's Hospital, N. Adelaide, Australia; Dominique Frameree, CHU de Jumet, Jumet, Annemarie van den Abeele, St. Lucas Campus Heilige Familie, Gent, and Jean-Marc Senterre, Hôpital de la Citadelle, Liege, Belgium; Arnaldo Colombo, Escola Paulista de Medicina, Sao Paulo, Brazil; Robert Rennie, University of Alberta Hospital, Edmonton, and Steve Sanche, Royal University Hospital, Saskatoon, Canada; Bijie Hu, Zhong Shan Hospital, Shanghai, Yingchun Xu, Peking Union Medical College Hospital, Beijing, Yingyuan Zhang, Hua Shan Hospital, Shanghai, and Nan Shan Zhong, Guangzhou Institute of Respiratory Diseases, Guangzhou, China; Pilar Rivas, Inst. Nacional de Cancerología, Bogotá, Angela Restrepo and Catalina Bedout, CIB, Medellin, and Ricardo Vega and Matilde Mendez, Hospital Militar Central, Bogotá, Colombia; Nada Mallatova, Hospital Ceske Budejovice, Ceske, and Stanislava Dobiasova, Zdravotini ustav se sidlem, Ostrave, Czech Republic; Julio Ayabaca, Hospital FF. AA HG1, Quito, and Jeannete Zurita, Hospital Vozandes, Quito, Ecuador; M. Mallie, Faculte de Pharmacie, Montpellier, and E. Candolfi, Institut de Parasitologie, Strasbourg, France; W. Fegeler, Universitaet Muenster, Münster, A. Haase, RWTH Aachen, Aachen, G. Rodloff, Inst. F. Med. Mikrobiologie, Leipzig, W. Bar, Carl-Thiem Klinikum, Cottbus, and V. Czaika, Humaine Kliniken, Bad Saarow, Germany; George Petrikos, Laikon General Hospital, Athens, Greece; Erzsébet Puskás MD, BAZ County Institute, Miskolc, Ilona Doczi, University of Szeged, Szeged, Mestyan Gyula, Medical University of Pecs, Pecs, and Radka Nikolova, Szt Laszlo Hospital, Budapest, Hungary; Uma Banerjee, All India Institute of Medical Sciences, New Delhi, India; Nathan Keller, Sheba Medical Center, TelHashomer, Israel; Vivian Tullio, Università degli Studi di Torino, Torino, Gian Carlo Schito, University of Genoa, Genoa, Giacomo Fortina, Ospedale di Novara, Novara, Gian Piero Testore, Univerrsita di Roma Tor Vergata, Rome, Domenico D'Antonio, Pescara Civil Hospital, Pescara, Giorgio Scalise, Instituto di Malattie Infettive, Ancona, Pietro Martino, Dept. di Biotechnologie, Rome, and Dr. Graziana Manno, Università di Genova, Genova, Italy; Kee Peng, University Malaya, Kuala Lumpur, Malaysia; Celia Alpuche and Jose Santos, Hospital General de Mexico, Mexico City, Eduardo Rodriguez Noriega, Universidad de Guadalajara, Guadalajara, and Mussaret Zaidi, Hospital General O'Horan, Merida, Mexico; Jacques F. G. M. Meis, Canisius Wilhemina Hospital, Nijmegen, The Netherlands; Egil Lingaas, Rikshospitalet, Oslo, Norway; Danuta Dzierzanowska, Children's Memorial Health Institute, Warsaw, and Waclaw Pawliszyn, Pracownia Bakteriologii, Krakow, Poland; Mariada Luz Martins, Inst. de Higiene e Medicina Tropical, Lisboa, Luis Albuquerque, Centro Hospitalar de Coimbra, Coimbra, Laura Rosado, Instituto Nacional de Saude, Lisboa, Rosa Velho, Hospital da Universidade de Coimbra, Coimbra, and Jose Amorim, Hospital de Santo Antonio, Porto, Portugal; Vera N. Ilina, Novosibirsk Regional Hospital, Novosibirsk, Olga I. Kretchikova, Institute of Antimicrobial Chemotherapy, Smolensk, Galina A. Klyasova, Hematology Research Center, Moscow, Sophia M. Rozanova, City Clinical Hospital No. 40, Ekaterinburg, Irina G. Multykh, Territory Center of Laboratory Diagnostics, Krasnodar, Nikolay N. Klimko, Medical Mycology Research Institute, St. Petersburg, Elena D. Agapova, Irkutsk Regional Childrens Hospital, Irkutsk, and Natalya V. Dmitrieva, Oncology Research Center, Moscow, Russia; Abdul Mohsen Al-Rasheed, Riyadh Armed Forces Hospital, Riyadh, Saudi Arabia; Jan Trupl, National Cancer Center, Leon Langsadl, NUTaRCH, Alena Vaculikova, Derer University Hospital, and Hupkova Helena, St. Cyril and Metod Hospital, Bratislava, Slovak Republic; Denise Roditi, Groote Schuur Hospital, Cape Town, Anwar Hoosen, GaRankuwa Hospital, Medunsa, H. H. Crewe-Brown, Baragwanath Hospital, Johannesburg, M. N. Janse van Rensburg, Pelanomi Hospital, UOFS, Bloemfontein, and Adriano Duse, Johannesburg General Hospital, Johannesburg, South Africa; Kyungwon Lee, Yonsei University College of Medicine, and Mi-Na Kim, Asan Medical Center, Seoul, South Korea; A. del Palacio, Hospital 12 De Octobre, and Aurora Sanchez-Sousa, Hospital Ramon y Cajal, Madrid, Spain; Jacques Bille, Institute of Microbiology CHUV, Lausanne, and K. Muhlethaler, Universitat Bern, Bern, Switzerland; Shan-Chwen Chang, National Taiwan University Hospital, Taipei, and Jen-Hsien Wang, China Medical College Hospital, Taichung, Taiwan; Malai Vorachit, Ramathibodi Hospital, Mahidol University, Bangkok, Thailand; Deniz Gur, Hacettepe University Children's Hospital, Ankara, and Volkan Korten, Marmara Medical School Hospital, Istanbul, Turkey; John Paul, Royal Sussex County Hospital, Brighton, Brian Jones, Glasgow Royal Infirmary, Glasgow, F. Kate Gould, Freeman Hospital, Newcastle, and Chris Kibbler, Royal Free Hospital, London, Nigel Weightman, Friarage Hospital, Northallerton, Ian M. Gould, Aberdeen Royal Hospital, Aberdeen, Ruth Ashbee, General Infirmary, P.H.L.S., Leeds, and Rosemarie Barnes, University of Wales College of Medicine, Cardiff, United Kingdom; Jose Vazquez, Harper Hospital, Wayne State University, Detroit, Mich., Ed Chan, Mt. Sinai Medical Center, New York, N.Y., Davise Larone, Cornell Medical Center NYPH, New York, N.Y., Ellen Jo Baron, Stanford Hospital and Clinics, Stanford, Calif., Mahmoud A. Ghannoum, University Hospitals of Cleveland, Cleveland, Ohio, Mike Rinaldi, University of Texas Health Science Center, San Antonio, Tex., Kevin Hazen, University of Virginia Health Systems, Charlottesville, Va., and Elyse Foraker, Christiana Care, Wilmington, Del.; and Heidi Reyes, Gen del Este Dr. Domingo Luciani, and Axel Santiago, Universitario de Caracas, Caracas, Venezuela.
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