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Antimicrobial Agents and Chemotherapy, October 2008, p. 3783-3785, Vol. 52, No. 10
0066-4804/08/$08.00+0 doi:10.1128/AAC.00473-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
Development of Caspofungin Resistance following Prolonged Therapy for Invasive Candidiasis Secondary to Candida glabrata Infection
George R. Thompson III,1*
Nathan P. Wiederhold,1,3,4
Ana C. Vallor,1
Nyria C. Villareal,1
James S. Lewis II,1,2 and
Thomas F. Patterson1
University of Texas Health Science Center at San Antonio, Department of Internal Medicine, Division of Infectious Diseases, MSC 7881, 7703 Floyd Curl Drive, San Antonio, Texas 78229,1
Department of Pharmacy, University Health System, San Antonio, Texas 78229,2
University of Texas at Austin College of Pharmacy, 1 University Station, A1900, Austin, Texas 78712,3
University of Texas Health Science Center at San Antonio, Pharmacotherapy Education and Research Center, MSC 6220, 7703 Floyd Curl Drive, San Antonio, Texas 782994
Received 9 April 2008/
Returned for modification 23 June 2008/
Accepted 20 July 2008

ABSTRACT
We report a case of
Candida glabrata invasive candidiasis that
developed reduced susceptibility to caspofungin during prolonged
therapy. Pre- and posttreatment isolates were confirmed to be
isogenic, and sequencing of hot spots known to confer echinocandin
resistance revealed an F659V substitution within the
FKS2 region
of the glucan synthase complex.

TEXT
The echinocandins have become first-line therapy in many centers
for the treatment of invasive candidiasis due to their proven
efficacy, the infrequency of side effects, and the favorable
drug interaction profile (
12,
16,
20,
23). However, reduced
susceptibility to these agents has been reported in patients
receiving therapy for invasive candidiasis and is primarily
due to mutations within highly conserved regions of
FKS1 and
FKS2, genes encoding subunits of the glucan synthase enzyme
complex (
8,
9,
21). We report a case of invasive candidiasis
caused by
Candida glabrata that developed reduced susceptibility
to caspofungin during a prolonged course of therapy with this
agent.
A 41-year-old previous orthotopic liver recipient, who had no previous antifungal exposure, developed C. glabrata candidemia 8 months after transplantation. Intravenous caspofungin (70-mg load, followed by 50 mg daily) was initiated, and the fungemia cleared within 24 h. Yet cultures of multiple sites remained positive: bronchoalveolar lavage cultures, thought to represent colonization, were positive on days 23 and 52 of therapy; peritoneal fluid and an abdominal wall abscess were positive on day 40; and blood cultures returned positive on day 53. Dialysis dependence, hepatic dysfunction, and drug interaction concerns precluded alternative antifungal agents. The patient died on day 61 of caspofungin therapy after the development of multiorgan failure. Broth microdilution testing performed according to CLSI (formerly NCCLS) standard M27-A2 methodology (17) demonstrated reduced caspofungin susceptibility (MICs of 2 and 8 µg/ml at 24 and 48 h, respectively) for C. glabrata isolate 7755 recovered from the peritoneal fluid on day 40 compared to isolate 7754 (MIC of 0.25 µg/ml) recovered from the blood prior to antifungal therapy.
Random amplification of polymorphic DNA using previously described methods and primers (AP50-1, OPA-18, and OPE-18) (1, 2) strongly suggested strain isogenicity for isolates 7754 and 7755 recovered from this patient. Band patterns were identical for these two isolates with each of the three primers used, while differences in band intensity and location were observed compared to the unrelated isolate 0562 with primers OPA-18 and AP50-1 (Fig. 1).
Conserved regions of the glucan synthase enzyme complex hot
spot regions were identified within the
C. glabrata genome sequence
(
http://cbi.labri.fr/Genolevures/index.php) for
C. glabrata FKS1 (Cg
FKS1) (CAGL0G01034g) and Cg
FKS2 (CAGL0K04037g). Genomic
DNA was exracted using a commercially available kit (MasterPure
yeast DNA purification kit; Epicentre Biotechnologies, Madison,
WI), and regions of interest were sequenced with primers prepared
at the UTHSCSA Advanced Nucleic Acid Core facility (Table
1).
Sequence analysis of susceptible isolate 7754 revealed wild-type
sequences in hot spots 1 and 2 of Cg
FKS1 and Cg
FKS2. However,
a mutation within hot spot 1 of Cg
FKS2 that conferred an F659V
amino acid substitution in CgFks2p was found in isolate 7755
with reduced caspofungin susceptibility.
Although rare, recent reports have illustrated the potential
for echinocandin resistance to emerge during therapy (
7,
10,
13,
14,
22). Many of these reports have identified mutations
within genes encoding subunits of the glucan synthase complex,
and all mutations described to date reside within highly conserved
regions of
FKS1 or its homolog,
FKS2 (
5,
6,
11,
21).
Candida albicans isolates comprise the majority of these cases, with
mutations leading to codon changes F641S, S645F, S645Y, S645P,
and R1361H (
13,
14,
21). Additionally, a mutation resulting
in amino acid change R1361G within the
FKS1 homolog in
Candida krusei has been described (
8).
Reduced echinocandin susceptibility and clinical failure have also been reported with C. glabrata. One case report detailed the emergence of caspofungin resistance and clinical failure after prolonged therapy, a finding supported by both in vitro and in vivo studies (10). However, no sequence analysis of either CgFKS1 or CgFKS2 was reported. Conversely, another study described a mutation within CgFKS2 resulting in an F659V codon change. Although no clinical information was provided, this mutation was proven to confer caspofungin resistance (9). The same mutation within CgFKS2 was also found in isolate 7755 in our patient and was associated with a marked increase in caspofungin MICs. Similarly, another recent case report also demonstrated a mutation within hot spot 1 of Fks1p in a C. glabrata isolate during caspofungin therapy leading to reduced susceptibility and clinical failure (3).
Despite the 8- to 32-fold increases in the caspofungin 24- and 48-h MICs for isolate 7755, anidulafungin and micafungin maintained potency against both 7754 and 7755 (Table 2). However, this difference in potencies between caspofungin and the other echinocandins was no longer present when susceptibility testing was repeated in the presence of 50% human serum. In this setting, the 24- and 48-h MICs for anidulafungin and micafungin increased 8- to 32-fold against isolate 7754 and 4- to 16-fold for isolate 7755. The prospect of using a different echinocandin when caspofungin resistance is encountered has been proposed (7, 10, 22) and is based on enhanced potency of anidulafungin and micafungin against Candida isolates observed in vitro (4, 18). Unfortunately, these observations have not translated into improved efficacy in murine models of invasive fungal infections. In these studies, in vivo efficacy correlated better with in vitro potency when tested in the presence of human serum (19, 25). The effect of serum on the activity of echinocandins is not fully understood. One potential explanation proposes the observed reduction in susceptibility is due to significant protein binding associated with these agents. Although this reduction in potency may be secondary to protein binding, significantly higher drug activity has been measured for micafungin than that predicted by the free drug concentration using protein binding data (15). The clinical relevance of reduced in vitro potency for the echinocandins in the presence of serum is unknown.
Continued exposure to antimicrobials is often associated with
the development of resistance, and as our case and previous
reports illustrate, this also may lead to the development of
echinocandin resistance in
Candida species, including non-
C. albicans isolates, during continued drug pressure with members
of this antifungal class. A heightened suspicion for reduced
echinocandin susceptibility as a possible cause of patient failure
is needed as the use of these agents continues to increase.

ACKNOWLEDGMENTS
We thank A.W. Fothergill, C. Kelly, J. E. Patterson, and M.
G. Rinaldi for their work (
24), which led us to further pursue
studies with these isolates that are presented in this article.
This research was funded in part by a National Institute of Health research grant to T.F.P. (5RO1DE018096).
G.R.T., A.C.V., and N.C.V. report no conflicts of interest. N.P.W. has received research support from Pfizer and Schering-Plough. J.S.L. has served as a consultant and speaker for Astellas, Merck, Pfizer, and Schering-Plough. T.F.P. has received research support from Merck, Pfizer, Schering-Plough, and Nektar Therapeutics and has served on the speakers' bureau for Merck and Pfizer and as a consultant for Astellas, Basilea, Merck, Nektar, Pfizer, Schering-Plough, and Stiefel Laboratories.

FOOTNOTES
* Corresponding author. Mailing address: Department of Internal Medicine, Division of Infectious Diseases, UTHSCSA, 7703 Floyd Curl Drive, San Antonio, TX 78229. Phone: (210) 567-6680. Fax: (210) 567-3303. E-mail:
thompsong2{at}uthscsa.edu 
Published ahead of print on 1 August 2008. 

REFERENCES
1 - Bautista-Muñoz, C., X. M. Boldo, L. Villa-Tanaca, and C. Hernández-Rodriguez. 2003. Identification of Candida spp. by randomly amplified polymorphic DNA analysis and differentiation between Candida albicans and Candida dubliniensis by direct PCR methods. J. Clin. Microbiol. 41:414-420.[Abstract/Free Full Text]
2 - Becker, K., D. Badehorn, S. Deiwick, G. Peters, and W. Fegeler. 2000. Molecular genotyping of Candida species with special respect to Candida (Torulopsis) glabrata strains by arbitrarily primed PCR. J. Med. Microbiol. 49:575-581.[Abstract/Free Full Text]
3 - Cleary, J. D., G. Garcia-Effron, S. W. Chapman, and D. S. Perlin. 2008. Reduced Candida glabrata susceptibility secondary to an FKS1 mutation developed during candidemia treatment. Antimicrob. Agents Chemother. 52:2263-2265.[Abstract/Free Full Text]
4 - Cota, J., M. Carden, J. R. Graybill, L. K. Najvar, D. S. Burgess, and N. P. Wiederhold. 2006. In vitro pharmacodynamics of anidulafungin and caspofungin against Candida glabrata isolates, including strains with decreased caspofungin susceptibility. Antimicrob. Agents Chemother. 50:3926-3928.[Abstract/Free Full Text]
5 - Douglas, C. M., J. A. D'Ippolito, G. J. Shei, M. Meinz, J. Onishi, J. A. Marrinan, W. Li, G. K. Abruzzo, A. Flattery, K. Bartizal, A. Mitchell, and M. B. Kurtz. 1997. Identification of the FKS1 gene of Candida albicans as the essential target of 1,3-β-D-glucan synthase inhibitors. Antimicrob. Agents Chemother. 41:2471-2479.[Abstract]
6 - Douglas, C. M., J. A. Marrinan, W. Li, and M. B. Kurtz. 1994. A Saccharomyces cerevisiae mutant with echinocandin-resistant 1,3-β-D-glucan synthase. J. Bacteriol. 176:5686-5696.[Abstract/Free Full Text]
7 - Hernandez, S., J. L. López-Ribot, L. K. Najvar, D. I. McCarthy, R. Bocanegra, and J. R. Graybill. 2004. Caspofungin resistance in Candida albicans: correlating clinical outcome with laboratory susceptibility testing of three isogenic isolates serially obtained from a patient with progressive Candida esophagitis. Antimicrob. Agents Chemother. 48:1382-1383.[Abstract/Free Full Text]
8 - Kahn, J. N., G. Garcia-Effron, M.-J. Hsu, S. Park, K. A. Marr, and D. S. Perlin. 2007. Acquired echinocandin resistance in a Candida krusei isolate due to modification of glucan synthase. Antimicrob. Agents Chemother. 51:1876-1878.[Abstract/Free Full Text]
9 - Katiyar, S., M. Pfaller, and T. Edlind. 2006. Candida albicans and Candida glabrata clinical isolates exhibiting reduced echinocandin susceptibility. Antimicrob. Agents Chemother. 50:2892-2894.[Abstract/Free Full Text]
10 - Krogh-Madsen, M., M. C. Arendrup, L. Heslet, and J. D. Knudsen. 2006. Amphotericin B and caspofungin resistance in Candida glabrata isolates recovered from a critically ill patient. Clin. Infect. Dis. 42:938-944.[CrossRef][Medline]
11 - Kurtz, M. B., G. Abruzzo, A. Flattery, K. Bartizal, J. A. Marrinan, W. Li, J. Milligan, K. Nollstadt, and C. M. Douglas. 1996. Characterization of echinocandin-resistant mutants of Candida albicans: genetic, biochemical, and virulence studies. Infect. Immun. 64:3244-3251.[Abstract]
12 - Kuse, E. R., P. Chetchotisakd, C. A. da Cunha, M. Ruhnke, C. Barrios, D. Raghunadharao, J. S. Sekhon, A. Freire, V. Ramasubramanian, I. Demeyer, M. Nucci, A. Leelarasamee, F. Jacobs, J. Decruyenaere, D. Pittet, A. J. Ullmann, L. Ostrosky-Zeichner, O. Lortholary, S. Koblinger, H. Diekmann-Berndt, and O. A. Cornely. 2007. Micafungin versus liposomal amphotericin B for candidaemia and invasive candidosis: a phase III randomised double-blind trial. Lancet 369:1519-1527.[CrossRef][Medline]
13 - Laverdiere, M., R. G. Lalonde, J. G. Baril, D. C. Sheppard, S. Park, and D. S. Perlin. 2006. Progressive loss of echinocandin activity following prolonged use for treatment of Candida albicans oesophagitis. J. Antimicrob. Chemother. 57:705-708.[Abstract/Free Full Text]
14 - Miller, C. D., B. W. Lomaestro, S. Park, and D. S. Perlin. 2006. Progressive esophagitis caused by Candida albicans with reduced susceptibility to caspofungin. Pharmacotherapy 26:877-880.[CrossRef][Medline]
15 - Mochizuki, N., M. Aibiki, and Y. Matsumoto. 2006. Abstr. 46th Intersci. Conf. Antimicrob. Agents Chemother., abstr. M-1598, p. 423.
16 - Mora-Duarte, J., R. Betts, C. Rotstein, A. L. Colombo, L. Thompson-Moya, J. Smietana, R. Lupinacci, C. Sable, N. Kartsonis, and J. Perfect. 2002. Comparison of caspofungin and amphotericin B for invasive candidiasis. N. Engl. J. Med. 347:2020-2029.[Abstract/Free Full Text]
17 - NCCLS. 2002. Reference method for broth dilution antifungal susceptibility testing of yeasts; approved standard, NCCLS document M27-A2. National Committee for Clinical Laboratory Standards, Wayne, PA.
18 - Ostrosky-Zeichner, L., J. H. Rex, P. G. Pappas, R. J. Hamill, R. A. Larsen, H. W. Horowitz, W. G. Powderly, N. Hyslop, C. A. Kauffman, J. Cleary, J. E. Mangino, and J. Lee. 2003. Antifungal susceptibility survey of 2,000 bloodstream Candida isolates in the United States. Antimicrob. Agents Chemother. 47:3149-3154.[Abstract/Free Full Text]
19 - Paderu, P., G. Garcia-Effron, S. Balashov, G. Delmas, S. Park, and D. S. Perlin. 2007. Serum differentially alters the antifungal properties of echinocandin drugs. Antimicrob. Agents Chemother. 51:2253-2256.[Abstract/Free Full Text]
20 - Pappas, P. G., C. M. Rotstein, R. F. Betts, M. Nucci, D. Talwar, J. J. De Waele, J. A. Vazquez, B. F. Dupont, D. L. Horn, L. Ostrosky-Zeichner, A. C. Reboli, B. Suh, R. Digumarti, C. Wu, L. L. Kovanda, L. J. Arnold, and D. N. Buell. 2007. Micafungin versus caspofungin for treatment of candidemia and other forms of invasive candidiasis. Clin. Infect. Dis. 45:883-893.[CrossRef][Medline]
21 - Park, S., R. Kelly, J. N. Kahn, J. Robles, M. J. Hsu, E. Register, W. Li, V. Vyas, H. Fan, G. Abruzzo, A. Flattery, C. Gill, G. Chrebet, S. A. Parent, M. Kurtz, H. Teppler, C. M. Douglas, and D. S. Perlin. 2005. Specific substitutions in the echinocandin target Fks1p account for reduced susceptibility of rare laboratory and clinical Candida sp. isolates. Antimicrob. Agents Chemother. 49:3264-3273.[Abstract/Free Full Text]
22 - Pelletier, R., I. Alarie, R. Lagace, and T. J. Walsh. 2005. Emergence of disseminated candidiasis caused by Candida krusei during treatment with caspofungin: case report and review of literature. Med. Mycol. 43:559-564.[CrossRef][Medline]
23 - Reboli, A. C., C. Rotstein, P. G. Pappas, S. W. Chapman, D. H. Kett, D. Kumar, R. Betts, M. Wible, B. P. Goldstein, J. Schranz, D. S. Krause, and T. J. Walsh. 2007. Anidulafungin versus fluconazole for invasive candidiasis. N. Engl. J. Med. 356:2472-2482.[Abstract/Free Full Text]
24 - Villareal, N. C., A. W. Fothergill, C. Kelly, J. E. Patterson, M. G. Rinaldi, and T. F. Patterson. 2004. Abstr. 44th Intersci. Conf. Antimicrob. Agents Chemother., abstr. M-1034, p. 417.
25 - Wiederhold, N. P., L. K. Najvar, R. Bocanegra, D. Molina, M. Olivo, and J. R. Graybill. 2007. In vivo efficacy of anidulafungin and caspofungin against Candida glabrata and association with in vitro potency in the presence of sera. Antimicrob. Agents Chemother. 51:1616-1620.[Abstract/Free Full Text]
Antimicrobial Agents and Chemotherapy, October 2008, p. 3783-3785, Vol. 52, No. 10
0066-4804/08/$08.00+0 doi:10.1128/AAC.00473-08
Copyright © 2008, American Society for Microbiology. All Rights Reserved.
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