Background The echinocandins are lipopeptides that can be employed as antifungal drugs that inhibit the synthesis of 1,3-β-glucans within the fungal cell wall. Anidulafungin and caspofungin are echinocandins used in the treatment of Candida infections and have activity against other fungi including Aspergillus fumigatus. The echinocandins are generally considered fungistatic against Aspergillus species. Methods Culture of A. fumigatus from conidia to microcolonies on a support of porous aluminium oxide (PAO), combined with fluorescence microscopy and scanning electron microscopy, was used to investigate the effects of anidulafungin and caspofungin. The PAO was an effective matrix for conidial germination and microcolony growth. Additionally, PAO supports could be moved between agar plates containing different concentrations of echinocandins to change dosage and to investigate the recovery of fungal microcolonies from these drugs. Culture on PAO combined with microscopy and image analysis permits quantitative studies on microcolony growth with the flexibility of adding or removing antifungal agents, dyes, fixatives or osmotic stresses during growth with minimal disturbance of fungal microcolonies. Significance Anidulafungin and caspofungin reduced but did not halt growth at the microcony level; additionally both drugs killed individual cells, particularly at concentrations around the MIC. Intact but not lysed cells showed rapid recovery when the drugs were removed. The classification of these drugs as either fungistatic or fungicidal is simplistic. Microcolony analysis on PAO appears to be a valuable tool to investigate the action of antifungal agents.
Douglas CM, D'Ippolito JA, Shei GJ, Meinz M, Onishi J, et al. (1997) Identification of the FKS1 gene of Candida albicans as the essential target of 1,3-beta-D-glucan synthase inhibitors. Antimicrob Agents Chemother 41: 2471–2479.
Antachopoulos C, Meletiadis J, Sein T, Roilides E, Walsh TJ (2008) Comparative in vitro pharmacodynamics of caspofungin, micafungin, and anidulafungin against germinated and nongerminated Aspergillus conidia. Antimicrob Agents Chemother 52: 321–328.
Hiemenz JW, Raad II, Maertens JA, Hachem RY, Saah AJ, et al. (2010) Efficiency of caspofungin as salvage therapy for invasive aspergillosis compared to standard therapy in a historical cohort. Eur J Clin Microbiol Infect Dis 29: 1387–1394.
Watabe E, Nakai T, Matsumoto S, Ikeda F, Hatano K (2003) Killing activity of micafungin against A. fumigatus hyphae assessed by specific fluorescent staining for cell viability. Antimicrob Agents Chemother 47: 1995–1998.
Ingham CJ, van den Ende M, Pijnenburg D, Wever PC, Schneeberger PM (2005) Growth and multiplexed analysis of microorganisms on a subdivided, highly porous, inorganic chip manufactured from Anopore. Appl Environ Microbiol 71: 8978–8981.
Ingham CJ, Sprenkels A, Bomer J, Molenaar D, van den Berg A, et al. (2007) The micro-Petri dish, a million-well growth chip for the culture and high-throughput screening of microorganisms. Proc Natl Acad Sci U S A 13: 18217–18222.
Ingham CJ, van den Ende M, Wever PC, Schneeberger PM (2006) Rapid antibiotic sensitivity testing and trimethoprim-mediated filamentation of clinical isolates of the Enterobacteriaceae assayed on a novel porous culture support. Med Microbiol 55. 1511–1519.
Hill TW, Loprete DM, Momany M, Ha Y, Harsch LM, et al. (2006) Isolation of cell wall mutants in A. nidulans by screening for hypersensitivity to Calcofluor White. Mycologia 98: 399–409.
Chiou CC, Mavrogiorgos N, Tillem E, He R, Walsh TJ (2001) Synergy, pharmacodynamics, and time-sequenced ultrastructural changes of the interaction between Nikkomycin Z and the echinocandin FK463 against Aspergillus fumigatus. Antimicrob Agents Chemo 12: 3310–3321.
Ingham CJ, Ter Maat J, de Vos WM (2011) Where bio meets nano: The many uses of porous aluminium oxide in biotechnology. Biotechnol Adv. doi:10.1016/j.biotechadv.2011.08.005.
Ingham CJ, Schneeberger PM (2012) The role of nanoporous materials in microbial culture. In: Hays JP, van Leeuwen W, editors. The role of new technologies in medical microbiological research and diagnosis. 1st ed. Sharjah, UAE.: Bentham Science Publishers Ltd. pp. 86–98.
Templeton SP, Buskirk AD, Law B, Green BJ, Beezhold DH (2011) Role of germination in murine airway CD8+ T-cell responses to Aspergillus conidia. PLoS One 6: e18777.
Jones BV, Young R, Mahenthiralingam E, Stickler DJ (2004) Ultrastructure of Proteus mirabilis swarmer cell rafts and role of swarming in catheter-associated urinary tract infection. Infect Immun 72: 3941–3950.
den Besten HM, Ingham CJ, van Hylckama Vlieg JE, Beerthuyzen MM, Zwietering MH, et al. (2008) Quantitative analysis of population heterogeneity of the adaptive salt stress response and growth capacity of Bacillus cereus ATCC 14579. Appl Environ Microbiol 73: 4797–4804.
