Methods and compositions useful in the detection and identification of species of Candida are disclosed. These species include
Candida albicans,
Candida glabrata,
Candida parapsilosis, and
Candida tropicalis, each of which is a causative agent for vaginal candidiasis. The compositions of the invention are combinations of oligonucleotides. These oligonucleotides include pairs of forward and reverse primers for
polymerase chain reactions, wherein each primer pair is capable of priming the synthesis of an
amplicon specific to one of
Candida albicans,
Candida glabrata,
Candida parapsilosis, and
Candida tropicalis, but preferably is not capable of priming the synthesis of an
amplicon specific to any of the other three species. In preferred embodiments, the forward primers of the primer pairs have identical sequences, while each
reverse primer of the primer pairs has a unique sequence relative to all of the other reverse primers; or the reverse primers of the primer pairs have identical sequences, while each
forward primer of the primer pairs has a unique sequence relative to all of the other forward primers. These unique primer sequences account for the species specificity of the
resultant amplicons. The oligonucleotides also include probes capable of detecting these amplicons, and sequencing primers for determining, in
primer extension reactions, the
nucleotide sequences contained within the amplicons. In preferred methods of the invention, a biological sample is tested for the presence of at least one isolate of
Candida albicans,
Candida glabrata,
Candida parapsilosis, and
Candida tropicalis by isolating
nucleic acid from the sample, attempting a
polymerase chain reaction in a mixture containing this
nucleic acid and a plurality of these primer pairs, ascertaining whether any
amplicon is produced in the mixture using an
oligonucleotide probe, and determining the sequence of any
resultant amplicon using the sequencing primers. The detection of an amplicon indicates that the sample contains at least one isolate of Candida albicans, Candida glabrata, Candida parapsilosis, or Candida tropicalis, and the
nucleotide sequence data is used to determine which of these four Candida species is present.