Jain N, Kohli R, Cook E, Gialanella P, Chang T, Fries B C
Department of Medicine and Microbiology and Immunology, Ullmann 1223, 1300 Morris Park Ave., Albert Einstein College of Medicine, Bronx, NY 10461, USA.
Appl Environ Microbiol. 2007 Mar;73(6):1697-703. doi: 10.1128/AEM.02439-06. Epub 2007 Jan 19.
Biofilm formation (BF) in the setting of candiduria has not been well studied. We determined BF and MIC to antifungals in Candida spp. isolates grown from urine samples of patients and performed a retrospective chart review to examine the correlation with risk factors. A total of 67 Candida spp. isolates were grown from urine samples from 55 patients. The species distribution was C. albicans (54%), C. glabrata (36%), and C. tropicalis (10%). BF varied greatly among individual Candida isolates but was stable in sequential isolates during chronic infection. BF also depended on the growth medium and especially in C. albicans was significantly enhanced in artificial urine (AU) compared to RPMI medium. In nine of the C. albicans strains BF was 4- to 10-fold higher in AU, whereas in three of the C. albicans strains and two of the C. glabrata strains higher BF was measured in RPMI medium than in AU. Determination of the MICs showed that planktonic cells of all strains were susceptible to amphotericin B (AMB) and caspofungin (CASPO) and that three of the C. glabrata strains and two of the C. albicans strains were resistant to fluconazole (FLU). In contrast, all biofilm-associated adherent cells were resistant to CASPO and FLU. The biofilms of 14 strains (28%) were sensitive to AMB (MIC(50) of <1 mug/ml). Correlation between degree of BF and MIC of AMB was not seen in RPMI grown biofilms but was present when grown in AU. A retrospective chart review demonstrated no correlation of known risk factors of candiduria with BF in AU or RPMI. We conclude that BF is a stable characteristic of Candida strains that varies greatly among clinical strains and is dependent on the growth medium. Resistance to AMB is associated with higher BF in AU, which may represent the more physiologic medium to test BF. Future studies should address whether in vitro BF can predict treatment failure in vivo.
念珠菌尿症中生物膜形成(BF)的研究尚不充分。我们测定了从患者尿液样本中分离出的念珠菌属菌株的BF及对抗真菌药物的最低抑菌浓度(MIC),并进行了回顾性病历审查以研究其与危险因素的相关性。共从55例患者的尿液样本中培养出67株念珠菌属菌株。菌种分布为白色念珠菌(54%)、光滑念珠菌(36%)和热带念珠菌(10%)。BF在各个念珠菌分离株之间差异很大,但在慢性感染期间连续分离株中较为稳定。BF还取决于生长培养基,尤其是白色念珠菌,与RPMI培养基相比,在人工尿液(AU)中BF显著增强。在9株白色念珠菌菌株中,AU中的BF比RPMI培养基高4至10倍,而在3株白色念珠菌菌株和2株光滑念珠菌菌株中,RPMI培养基中的BF高于AU。MIC测定表明,所有菌株的浮游细胞对两性霉素B(AMB)和卡泊芬净(CASPO)敏感,3株光滑念珠菌菌株和2株白色念珠菌菌株对氟康唑(FLU)耐药。相比之下,所有与生物膜相关的黏附细胞对CASPO和FLU耐药。14株菌株(28%)的生物膜对AMB敏感(MIC50<1μg/ml)。在RPMI培养基中生长的生物膜中未观察到BF程度与AMB的MIC之间的相关性,但在AU中生长时存在相关性。回顾性病历审查表明,念珠菌尿症的已知危险因素与AU或RPMI中的BF无相关性。我们得出结论,BF是念珠菌菌株的一个稳定特征,在临床菌株中差异很大,且取决于生长培养基。对AMB的耐药性与AU中较高的BF相关,AU可能是测试BF更接近生理状态的培养基。未来的研究应探讨体外BF是否能预测体内治疗失败。