FTIR characterization of Candida species: a study on some reference strains and pathogenic C. albicans isolates from HIV þ patients G.D. Sockalingum a , C. Sandt a , D. Toubas b , J. Gomez d , P. Pina c , I. Beguinot e , F. Witthuhn b , D. Aubert b , P. Allouch c , J.M. Pinon b , M. Manfait a,* a Unite ´ Me ´DIAN, CNRS-FRE 2141, IFR 53, UFR de Pharmacie, Universite ´ de Reims-Champagne-Ardenne, 51 rue Cognacq Jay, 51096 Reims Cedex, France b Laboratoire de Parasitologie Mycologie, CHU, Ho ˆpital Maison Blanche, IFR 53, EA 2070, Faculte ´ de Me ´decine, Universite ´ de Reims Champagne-Ardenne, 51096 Reims, France c Service d’Hygie `ne Hospitalie `re, Ho ˆpital Mignot, CH de Versailles, 78157 Le Chesnay, France d Infectious Diseases Department, Universidad Nacional de Colombia, Santafe ´ de Bogota ´, Bogota ´, D.C., Colombia e Service de Maladies Infectieuses, Ho ˆpital Robert Debre ´, 51092 Reims Cedex, France Abstract ATR–FTIR has been used together with principal components analysis to study some reference strains belonging to five different Candida species and 20 Candida albicans isolates from three HIV þ patients under different fluconazole regimens. The five reference strains were easily differentiated by using first derivative spectra of the carbohydrate region comprising the spectral range 900–1200 cm 1 . For the C. albicans clinical isolates, classification obtained by Fourier-transform infrared (FTIR) spectroscopy was compared with data from the genotypic method, PFGE. Results show a good correlation between the two methods for one patient who presented a partially conserved immune system with no previous fluconazole treatment, where all C. albicans strains isolated were susceptible to this antifungal agent. Divergences in the two methods appear for the two immuno-compromised patients receiving long-term fluconazole treatment. It is very probable that such iterative antifungal treatment can cause strong alterations in the yeast cell wall membrane and that the mismatch of the two techniques highlights the complex situation of strain-level identification and differentiation of clinical isolates originating from patients under prolonged treatment. # 2002 Elsevier Science B.V. All rights reserved. Keywords: FTIR; Candida species; HIV þ patients 1. Introduction Candida species are generally differentiated and identified on the basis of biochemical reactions and morphological features. However, confusion in the classification of species can occur when phenotypic variations exist within species such as Candida albi- cans [1]. The characterization within species is even more complicated in cases of oropharyngeal yeast flora and such is the case with human immunodefi- ciency virus positive (HIV þ )-infected patients, where genetic variation occurs in clinical isolates. Among all the described species, only about 10 are of medical interest and considered as pathogenic to man. Vibrational Spectroscopy 28 (2002) 137–146 * Corresponding author. Tel.: þ33-3-26-91-35-74; fax: þ33-3-26-91-35-50. E-mail address: michel.manfait@univ-reims.fr (M. Manfait). 0924-2031/02/$ – see front matter # 2002 Elsevier Science B.V. All rights reserved. PII:S0924-2031(01)00152-7