"Room temperature" use of CHROMagar Candida

Biochemical typing and evaluation of pathogenicity in vulvovaginal isolates of Candida albicans complex

Introduction

Candida albicans, C. dubliniensis, and C. africana form the Candida albicans complex.

Objective

To identify the phenotypic and pathogenic characteristics of isolates of the C. albicans complex preserved in a collection.

Materials and methods

Three hundred presumptive strains of the C. albicans complex were evaluated using CHROMagarTM Candida. Germ tube production was determined by three methods, chlamydospores formation was assessed and colonies were characterized in artisanal agars (Rosmarinus officinalis and Nicotiana tabacum). MALDI-TOF was used as the gold standard identification test. To detect pathogenicity factors, we evaluated the hemolytic activity of each isolate and cocultured with Staphylococcus aureus, coagulase enzyme production, and biofilm formation.

Results

Out of the 300 isolates, 43.7% produced germ tube in the heart-brain infusion broth and 47% of the isolates produced chlamydospores. In the artisan media, 6% of the isolates produced brown colonies on rosemary agar and 5% did so on tobacco agar. None of the strains hemolyzed the blood agar alone or cocultured with S. aureus. However, 50% of the isolates hemolyzed the potato dextrose agar supplemented with blood. All strains were coagulase producers, and biofilm production was variable. For germ tube production, the human serum method showed the same positivity as the milk broth method. All isolates were identified as C. albicans by MALDI-TOF.

Conclusions

The use of proteomics, molecular tests or a combination of methods is required for species identification.

Evaluation of CHROMagarTM Candida Plus chromogenic agar for the presumptive identification of Candida auris

Skin colonization by the emerging pathogen Candida auris is common in outbreaks within medical settings. Culture-based screening of patients is an effective management strategy to control the pathogen, and the newly developed CHROMagar^TM Candida Plus medium is claimed to enable the presumptive identification of C. auris. Here, we evaluated the use of this medium with 63 C. auris strains comprising its four well-established clades, as well as genetically related comparators, including species from the Metschnikowia clade. The colors and halos of both confluent growth and discrete colonies of all tested strains were compared. We found that on CHROMagar^TM Candida Plus, C. auris formed characteristic white colonies with blue-green halos that were more evident after 72 h of incubation at 35 ℃ than after 48 h. However, distinguishing between closely related species such as Candida haemulonii, Candida pseudohaemulonii, and Candida duobushaemulonii required the consideration of parameters other than color, including colony size and growth ability at 35 ℃. In conclusion, the novel chromogenic medium CHROMagar^TM Candida Plus constitutes an easy screening tool for C. auris. This article is protected by copyright. All rights reserved.

Identification of Fungi Isolated from Oral Cavity of Patients with HIV Using MALDI-TOF MS

BACKGROUND

A growing incidence of invasive fungal infections, especially among immunocompromised patients, has given increased significance to microbiological diagnostics of yeast-like fungi. More accurate and faster fungi identification methods that can compete with classical methods are being searched for. In this paper, classical microbiological methods are compared to MALDI-TOF MS (matrix-assisted laser desorption/ionization time-of-flight mass spectrometry).

METHODS

The diagnostic material was collected from buccal mucosa from 98 adults, including 69 with HIV. Only positive cultures were included in the study.

RESULTS

Matching results were obtained in 45 samples, and there were nonmatching results in 35 samples, with the majority of these in the study group, constituting 50% of identifications within this group. A particularly common mistake resulting from the use of classical methods is the false identification of C. dubliniensis as C. albicans. Additionally, C. tropicalis proves to be difficult to identify.

CONCLUSIONS

Our results and literature data suggest that MALDI-TOF MS should be considered an effective alternative to classical methods in terms of fungi identification, especially among HIV-positive patients, due to the different morphology of fungal colonies.

Isolation, characterization, and molecular identification of Candida species from urinary tract infections

BACKGROUND AND PURPOSE

Candida species are reportedly the most common human fungal pathogens. The incidence of urinary tract infections (UTIs) caused by Candida pathogens has increased in recent decades. However, such infections rarely occur in the absence of any predisposing factors. Regarding this, the aim of the present study was to identify the Candida species causing UTIs and determine the predisposing factors for candiduria.

MATERIALS AND METHODS

The current study was conducted on 1,450 urine samples obtained from patients suspected of UTI. Out of this number, 19 cases were candidiasis, and 2 cases were mixed infections caused by bacteria and fungi. Candida species were diagnosed differentially using the germ tube test, colony staining on CHROMagar medium, intracellular beta-glucosidase enzyme activity, and glucose absorption pattern. Then, the colonies with the same morphology were confirmed by the DNA sequencing of internal transcribed spacer regions.

RESULTS

According to the results, 38%, 28.6%, 14.3%, and 9.5% of the isolates were identified as C. albicans, C. glabrata, C. tropicalis, and C. kefir/C. krusei, respectively. The presence of one or more predisposing factors was proved in all patients in whom diabetes was the most prevalent predisposing factor (21.1%).

CONCLUSION

Based on the obtained results, C. albicans species was the most prevalent fungal species. In addition, urinary fungal infections were less prevalent than bacterial urinary infections.

Rapid and Accurate Identification of Candida albicans and Candida dubliniensis by Real-Time PCR and Melting Curve Analysis

OBJECTIVE

Candida albicans and Candida dubliniensis are germ tube-positive pathogenic yeast species. Accurate identification of these two species is warranted since C. albicans is a highly pathogenic species while C. dubliniensis exhibits increased adherence to buccal epithelial cells, reduced susceptibility to azoles and resistance to flucytosine. We have developed a duplex real-time PCR assay for rapid detection and differentiation between clinical C. albicans and C. dubliniensis isolates.

MATERIALS AND METHODS

A duplex real-time PCR assay was developed by using two species-specific primer pairs and SYBR Green dye to differentiate C. albicans and C. dubliniensis isolates via melting curve analysis of real-time PCR amplicons. Amplification products were also analyzed by agarose gel electrophoresis to confirm real-time PCR results.

RESULTS

Melting temperatures (Tm) for reference strains of C. albicans and C. dubliniensis were 86.55 and 82.75°C, respectively. No amplicon was obtained with DNA from reference strains of 8 other common Candida spp. When real-time PCR was applied on 226 clinical isolates previously identified by the Vitek 2 system and/or PCR sequencing of rDNA, Tm values for C. albicans (n = 113) and C. dubliniensis (n = 98) were 86.68 ± 0.529 and 82.616 ± 0.535°C, respectively. The results were confirmed by agarose gel electrophoresis. No amplicon was obtained from 15 isolates belonging to 9 other Candida spp.

CONCLUSIONS

The real-time PCR assay described here does not require prior identification of clinical yeast isolates as C. albicans/C. dubliniensis by germ tube formation and accurately reports results within 2 h. Detection of amplicons by agarose gel electrophoresis is also suitable for resource-poor settings devoid of real-time PCR facilities.

Identification and characterization of nine atypical Candida dubliniensis clinical isolates

Candida dubliniensis is a pathogenic yeast of the genus Candida closely related to Candida albicans. The phenotypic similarity of these two species often leads to misidentification of C. dubliniensis isolates in clinical samples. DNA-based methods continue to be the most effective means of discriminating accurately between the two species. Here, we report on the identification of nine unusual Candida isolates that showed ambiguous identification patterns on the basis of their phenotypic and immunological traits. The isolates were categorized into two groups. Group I isolates were unable to produce germ tubes and chlamydospores, and to agglutinate commercial latex particles coated with a mAb highly specific for C. dubliniensis. Group II isolates grew as pink and white colonies on CHROMagar Candida and ChromID Candida, respectively. Carbohydrate assimilation profiles obtained with API/ID32C together with PCR amplification with specific primers and DNA sequencing allowed reliable identification of the nine unusual clinical isolates as C. dubliniensis.

[Contribution of the chromogenic medium CHROMagar(®)Candida in mycological diagnosis of yeasts]

The incidence of invasive candidiasis has increased dramatically over the last decades due to a larger number of patients at risk. The diagnosis remains difficult as the clinical presentation is not specific and the biological diagnosis usually takes several days to become positive. We propose in this work through a prospective study to evaluate the contribution of a chromogenic medium CHROMagar(®) (Becton-Dickinson) in the mycological diagnosis of Candida. We selected 680 samples from patients hospitalized in the intensive care unit for epidemiological surveillance over a period of 11 weeks. We treated samples by culture on Sabouraud and on CHROMagar(®). The species identification was performed by chlamydosporulation test and carbohydrate assimilation tests. We found that the CHROMagar(®)Candida evaluated in our work was a valuable tool in the primary culture in differentiating the most frequently isolated yeast species and in better detection of mixed cultures.

Oral microflora and their relation to risk factors in HIV+ patients with oropharyngeal candidiasis

OBJECTIVE

The purpose of this study was to determine the prevalence of oral microflora and association of oral candidiasis and multiple risk factors in HIV(+) patients.

PATIENTS AND METHODS

The present study included 100 HIV-infected patients participated in Imam Khomeini Hospital, Tehran, Iran for Oropharyngeal candidiasis (OPC) and HIV. We assessed the presence or absence of OPC, and samples were obtained from the oral cavity and direct microscopic examination, gram staining and culture on standard microbiological media were performed in all patients. CD4(+) cell count/CD4(+) percentage were also calculated.

RESULTS

The demographic characteristics showed that the patients had a mean age of 32.3 years old, 78% male and 22% female. Patients belonging to 'O(+)' blood group (27%) were more prone to develop OPC. A total of 460 bacterial colonies were obtained and Streptococcus mutans (15.4%) was the most frequently isolated species in the HIV(+) patients, followed by Staphylococcus epidermidis (12.8%) and Corynebacterium (8.7%). In addition, 254 yeasts (from four different genera) were isolated from the patient under study. Candida species (94.4%) were the most frequently obtained genera, followed by Saccharomyces (2.4%), Kluyveromyces and Cryptococcus (1.6% for both) species. Candida albicans (37.2%) was the most common species isolated from HIV(+) patients with OPC and its frequency was significantly higher than that of other Candida species (P<0.05). Candida glabrata, C. dubliniensis, C. tropicalis, C. parapsilosis, C. krusei, C. lusitaniae, C. guilliermondii and C. norvegensis were also identified. Forty percent of the patients had angular cheilitis as the most frequent clinical variant. The mean CD4(+) cell counts were 154.5 cells/μL, with a range of 8 to 611 cells/μL. Thirty percent patients had a CD4(+) cell count between 101 and 200 cells/μL (28.7% of total yeasts isolated). Yeast and bacteria counts did not differ statistically among HIV(+) patients' subgroups with different levels of CD4(+) cells counts.

CONCLUSION

Our results showed that yeasts of the genus Candida were isolated at a comparable rate from the oral cavity of HIV(+) patients and there was no significant difference of the variables CD4(+) cell count and yeast counts. The findings of this study would be helpful in any further study, which, if done prospectively on a large cohort, can be confirmatory.

Candida albicans or Candida dubliniensis?

Candida albicans is increasing as an opportunistic pathogen causing candidemia and candidiasis worldwide. In addition, other non-albicans Candida species are now also associated with pertinent infections. These include the closely related C. dubliniensis, which shares many phenotypic similarities with C. albicans. These similarities pose problems in the identification of isolates and have previously led to misidentification of these species. As a result, several identification techniques based on phenotypic and genotypic characteristics have been developed to differentiate between these Candida species. This review will focus on the similarities and differences between these two Candida species highlighting different identification methods and their advantages and disadvantages.

Performance of Chromogenic Candida agar and CHROMagar Candida in recovery and presumptive identification of monofungal and polyfungal vaginal isolates

Chromogenic Candida agar (OCCA) is a novel medium facilitating isolation and identification of Candida albicans, C. tropicalis, and C. krusei, as well as indicating polyfungal population in clinical samples. We compare the performance of OCCA, to CHROMagar Candida (CAC) and Sabouraud chloramphenicol agar (SCA). Vaginal swab samples from 392 women were simultaneously inoculated onto three study media. A total of 161 (41.1%) were found to be positive for fungi of which 140 (87%) were monofungal, and 21 (13%) polyfungal. One-hundred and fifty-seven samples (97.5%) were positive on CAC, 156 (96.9%) on OCCA, 148 (91.9%) on SCA and 144 (89.4%) samples were positive on all three media. The yeasts were identified by conventional methods including germ tube test, microscopic morphology on cornmeal-Tween 80 agar, and the commercial API 20C AUX. The 182 isolates were C. albicans (n = 104), C. glabrata (n = 51), C. krusei (n = 7), C. tropicalis (n = 5), C. famata (n = 3), C. kefyr (n = 3), C. zeylanoides (n = 3), C. colliculosa (n = 2), and other species of Candida (n = 4). Among the 21 polyfungal populations, 20 (95.2%) were detected in OCCA, 14 (66.7%) in CAC, and 13 (61.9%) in CAC and OCCA (P <0.05). Most polyfungal populations (47.6%) yielded C. albicans + C. glabrata. The efficiency of both chromogenic media for C. albicans was >or=92.9% at 72 h. OCCA is more efficient and reliable for rapidly identifying C. albicans and polyfungal populations than CAC. However, CAC is more efficient for identifying C. krusei and C. tropicalis. A chromogenic agar with a higher isolation rate of yeasts and better detection of polyfungal populations than SCA, is suggested as a medium of first choice when available.

Comparison of phenotypic methods for the identification of Candida dubliniensis

BACKGROUND/PURPOSE

Mixed infections caused by different Candida species are the rule rather than the exception. The discrimination between the two closely related species Candida albicans and Candida dubliniensis is not trivial. Therefore, there is a need for fast, reliable, and inexpensive methods with high specificity for the identification and differentiation of these two Candida species, which are frequently detected in the oral cavities of patients with a human immunodeficiency virus infection.

METHODS

We applied several phenotypic identification methods (growth on Rice-agar, Bird-seed agar, CHROMagar Candida, API ID 32C; growth at 42 degrees C and 45 degrees C) and compared them with genotyping by arbitrarily primed-polymerase chain reaction.

RESULTS

A sensitivity of 44% for the identification of C. dubliniensis was achieved for growth on Rice-agar, 97% for discrimination on Bird-seed agar, 95% with the assimilation profile index API ID 32C, and 97% when grown at 45 degrees C. We found two API codes not described for C. dubliniensis so far. Additionally, 88% of our C. dubliniensis isolates assimilated palatinose, in contrast to the 1% described in the API reference manual.

CONCLUSION

According to our results, cultivation of Candida isolates on Bird-seed agar after screening on CHROMagar Candida is a very sensitive, simple, and cost-effective method for discriminating C. dubliniensis from C. albicans in routine practice.

Production of white colonies on CHROMagar Candida medium by members of the Candida glabrata clade and other species with overlapping phenotypic traits

We hypothesized that species of the Candida glabrata clade and species with phenotypic traits that overlap those of C. glabrata would produce white colonies on CHROMagar Candida medium. Of 154 isolates (seven species) tested, C. bracarensis, C. nivariensis, C. norvegensis, C. glabrata, and C. inconspicua produced white colonies; the Pichia fermentans group and C. krusei did not. Many of these species are difficult to identify phenotypically; white colonies may signal the need for the use of molecular approaches.

Yeast identification--past, present, and future methods

The focus of this review is the evolution of biochemical phenotypic yeast identification methods with emphasis on conventional approaches, rapid screening tests, chromogenic agars, comprehensive commercial methods, and the eventual migration to genotypic methods. As systemic yeast infections can be devastating and resistance is common in certain species, accurate identification to the species level is paramount for successful therapy and appropriate patient care.

Evaluation of the new chromogenic medium Candida ID 2 for isolation and identification of Candida albicans and other medically important Candida species

The usefulness of Candida ID 2 (CAID2) reformulated medium (bioMérieux, France) has been compared with that of the former Candida ID (CAID; bioMérieux), Albicans ID 2 (ALB2; bioMérieux), and CHROMagar Candida (CAC; Chromagar, France) chromogenic media for the isolation and presumptive identification of clinically relevant yeasts. Three hundred forty-five stock strains from culture collections, and 103 fresh isolates from different clinical specimens were evaluated. CAID2 permitted differentiation based on colony color between Candida albicans (cobalt blue; sensitivity, 91.7%; specificity, 97.2%) and Candida dubliniensis (turquoise blue; sensitivity, 97.9%; specificity, 96.6%). Candida tropicalis gave distinguishable pink-bluish colonies in 97.4% of the strains in CAID2 (sensitivity, 97.4%; specificity, 100%); the same proportion was reached in CAC, where colonies were blue-gray (sensitivity, 97.4%; specificity, 98.7%). CAC and CAID2 showed 100% sensitivity values for the identification of Candida krusei. However, with CAID2, experience is required to differentiate the downy aspect of the white colonies of C. krusei from other white-colony-forming species. The new CAID2 medium is a good candidate to replace CAID and ALB2, and it compares well to CAC for culture and presumptive identification of clinically relevant Candida species. CAID2 showed better results than CAC in some aspects, such as quicker growth and color development of colonies from clinical specimens, detection of mixed cultures, and presumptive differentiation between C. albicans and C. dubliniensis.

Clinical and experimental evaluation of a new chromogenic medium (OCCAR, Oxoid) for direct identification of Candida albicans, C. tropicalis and C. krusei

Oxoid Chromogenic Candida Agar (OCCA) is a new commercial ready-to-use medium that contains chromogenic substrates for rapid detection and specific identification of Candida albicans, C. tropicalis and C. krusei. We evaluated the performance of this medium with 364 clinical specimens and 31 subcultures, and examined its ability to support the growth of small inocula of six reference strains. CHROMagar Candida was used as the reference medium. OCCA permitted the growth of most important yeasts, and readily discriminated among Candida spp. in clinical specimens, including mixed cultures.

Presumptive identification of Candida species other than C. albicans, C. krusei, and C. tropicalis with the chromogenic medium CHROMagar Candida

Background

CHROMagar Candida (CaC) is increasingly being reported as a medium used to differentiate Candida albicans from non-albicans Candida (NAC) species. Rapid identification of NAC can assist the clinician in selecting appropriate antifungal therapy. CaC is a differential chromogenic medium designed to identify C. albicans, C. krusei, and C. tropicalis based on colony color and morphology. Some reports have proposed that CaC can also reliably identify C. dubliniensis and C. glabrata.

Methods

We evaluated the usefulness of CaC in the identification of C. dubliniensis, C. famata, C. firmetaria, C. glabrata, C. guilliermondii, C. inconspicua, C. kefyr, C. lipolytica, C. lusitaniae, C. norvegensis, C. parapsilosis, and C. rugosa.

Results

Most NAC produced colonies that were shades of pink, lavender, or ivory. Several isolates of C. firmetaria and all C. inconspicua produced colonies difficult to differentiate from C. krusei. Most C. rugosa isolates produced unique colonies with morphology like C. krusei except in a light blue-green color. C. glabrata isolates produced small dark violet colonies that could be differentiated from the pink and lavender colors produced by other species. All seventeen isolates of C. dubliniensis produced green colonies similar to those produced by C. albicans.

Conclusion

C. glabrata and C. rugosa appear distinguishable from other species using CaC. Some NAC, including C. firmetaria and C. inconspicua, could be confused with C. krusei using this medium.

Four cases of Candida albicans infections with isolates developing pink colonies on CHROMagar Candida plates

Candida albicans, the most commonly isolated yeast species, is typically identified by its green colony-colour on CHROMagar Candida plates. We here report four cases of Candida albicans infections, in which the initial identification was non-albicans isolates due to a clear pink colour of the colonies on CHROMagar Candida plates. However, classical phenotypic criteria, biochemical assimilation pattern and molecular characterisation identified all four isolates as C. albicans isolates.

Use of chromogenic medium in the isolation of yeasts from clinical specimens

Over a 1 year period 3296 specimens submitted for fungal culture were plated onto routine mycological media (RM) and CHROMagar Candida (CaC) to evaluate the capability of CaC to improve on RM. With RM, cultures producing single yeast isolates were identified from 802 specimens. CaC produced similar results, with 76 % agreement. Of 761 specimens that yielded a single Candida species by RM, 615 (81 %) produced one or more yeast isolates using CaC. Of concern, 132 negative CaC cultures corresponded to specimens that yielded C. albicans alone on RM. When yeasts were recovered, CaC correctly identified 98 % of C. albicans, 93 % of Candida tropicalis, 96 % of Candida glabrata and 100 % of Candida krusei based on typical colours. CaC did potentially improve on RM by detecting yeasts in 91 specimens that yielded none by routine methods. CaC was noted to recover more yeast isolates than RM when mixed cultures were detected. Overall, the role of CaC in improving RM appears limited.

Practical bench comparison of BBL CHROMagar Orientation and standard two-plate media for urine cultures

A total of 1023 urine samples sent for routine culture were plated onto sheep blood and MacConkey agars and a BBL CHROMagar Orientation (CO; Becton Dickinson, Cockeysville, Md.) plate, and the results were compared. Of these, 250 urine samples (24%) grew >10000 CFU of one or two putative pathogens/ml and 773 showed no growth (NG), mixed growth of <10000 CFU/ml, or three or more strains (mixed). The CO and conventional medium results agreed completely for 595 cultures with NG or <10000 CFU/ml. An additional 178 urine samples yielded clinically insignificant differences. Both medium sets essentially agreed on quantities and identification for 400 single-pathogen cultures and 9 mixed cultures. With the caveat that CO cannot differentiate Klebsiella, Enterobacter, and Serratia spp., enteric pathogens were identified only by morphology and color on CO. Direct visual differentiation of group B streptococci from lactobacilli is not possible, but lactobacillus cells always exhibited easily recognizable morphology on Gram stain. Of 108 paired organism susceptibility results encompassing 2268 drug-pathogen combinations, there were 3% errors and only 1% very major errors. Use of CO allowed a >50% reduction in inoculation time and a >20% reduction in work-up time. For our laboratory, with 50% "no growth" and ca. 25% significant results (50% Escherichia coli), CO allowed time and workup cost savings for a majority of cultures. A cost analysis (time and supplies for our laboratory) showed that if CO is used alone, the break-even level for CO pricing is US dollars 1.78; if CO and blood agar are both used, the break-even pricing for CO is US dollars 1.53.

Recomendaciones para el diagnóstico micológico y estudios de sensibilidad a los antifúngicos

The guidelines presented herein, which are based on the indications established by various studies and expert opinions, analyze several issues related to laboratory diagnosis of invasive fungal infections in immunosuppressed patients.

An epidemiological survey of vulvovaginal candidiasis in Italy

Eight Italian hospital or University gynecology clinics participated in a prospective survey of patients with culture-confirmed symptomatic vulvovaginal candidiasis (VVC) (October 1999 to March 2001). Of 1138 patients recruited in the study, 931 were evaluable. A recent history of VVC was documented in 43.5% patients (358/823) with a mean number of 2.9+/-2.7 episodes per patient (N=302). A total of 77 patients (10.0%) had a history of recurrent VVC (four and more episodes in a 12-month period). The most frequent associated factors were related to life style: synthetic fabric underwear, vaginal douching and bike, training bike and motorbike (about 1/3 each). Oral contraception was found in 20.8% patients, recent antibiotic use in 15.9% patients, current pregnancy concerned 10.3% patients while 3.4% patients were taking hormonal replacement therapy. Diabetes, corticosteroids or HIV were rarely encountered. Yeast was documented by direct microscopy in 78.3% patients (448/572). A positive culture was obtained in 98.3% patients (909/925). Candida albicans was the predominant species (77.1%), followed by Candida glabrata (14.6%) and Candida krusei (4.0%). With the exception of one center with a lower proportion of C. albicans, this latter represented between 75 and 85% of the isolates. Overall, this study confirmed the preponderant role played by C. albicans in either sporadic and recurrent VVC.

Direct isolation of Candida spp. from blood cultures on the chromogenic medium CHROMagar Candida

CHROMagar Candida is a selective and differential chromogenic medium that has been shown to be useful for identification of Candida albicans, Candida krusei, Candida tropicalis, and perhaps Candida glabrata. Colony morphology and color have been well defined when CHROMagar Candida has been used to isolate yeast directly from clinical specimens, including stool, urine, respiratory, vaginal, oropharyngeal, and esophageal sources. Direct isolation of yeast on CHROMagar Candida from blood cultures has not been evaluated. We evaluated whether the color and colony characteristics produced by Candida spp. on CHROMagar Candida were altered when yeasts were isolated directly from blood cultures. Fifty clinical isolates of Candida were inoculated into aerobic and anaerobic blood culture bottles and incubated at 35 degrees C in an automated blood culture system. When growth was detected, an aliquot was removed and plated onto CHROMagar Candida. As a control, CHROMagar Candida plates were inoculated with the same isolate of yeast grown on Sabouraud dextrose agar simultaneously. No significant difference was detected in color or colony morphology between the blood and control isolates in any of the tested organisms. All C. albicans (n = 12), C. tropicalis (n = 12), C. glabrata (n = 9), and C. krusei (n = 5) isolates exhibited the expected species-specific colony characteristics and color, whether isolated directly from blood or from control cultures. CHROMagar Candida can be reliably used for direct isolation of yeast from blood cultures. Direct isolation could allow mycology laboratories to more rapidly identify Candida spp., enable clinicians to more quickly make antifungal agent selections, and potentially decrease patient morbidity and mortality.

Use of amplified fragment length polymorphism analysis to identify medically important Candida spp., including C. dubliniensis

Non-Candida albicans Candida species are increasingly being isolated. These species show differences in levels of resistance to antimycotic agents and mortality. Therefore, it is important to be able to correctly identify the causative organism to the species level. Identification of C. dubliniensis in particular remains problematic due to the high degree of phenotypic similarity between this species and C. albicans. The use of amplified fragment length polymorphism (AFLP) analysis as an identification method for medically important Candida species was investigated. Our results show very clear differences among medically important Candida species. Furthermore, when screening a large collection of clinical isolates previously identified on CHROMagar as C. albicans, we found a misidentification rate of 6%. AFLP analysis is universally applicable, and the patterns can easily be stored in a general, accessible database. Therefore, AFLP might prove to be a reliable method for the identification of medically important Candida species.

Persistence of pigment production by yeast isolates grown on CHROMagar Candida medium

We evaluated the persistence of pigmentation in yeast isolates grown on the chromogenic medium CHROMagar Candida over 7 days. Candida, Cryptococcus, and Trichosporon isolates were inoculated alone or mixed onto duplicate sets of plates and incubated at 30 and 35 degrees C. Candida albicans and Candida krusei were readily identified throughout the reading period, but Candida glabrata was difficult to differentiate from other species until the 3- or 4-day time point. Candida tropicalis produced colonies similar to those of rare Cryptococcus and Trichosporon species, and mixed cultures were often difficult to identify as such.

Can the diagnosis of recurrent vulvovaginal candidosis be improved by use of vaginal lavage samples and cultures on chromogenic agar?

OBJECTIVE

To investigate if introital and vaginal flushing samples inoculated on chromogenic agar could increase the recovery rate and rapid identification of Candida and non-albicans species, as compared to culture of posterior vaginal fornix samples on Sabouraud agar and speciation of isolates by biochemical tests.

METHODS

Samples from the introitus and the posterior vaginal fornix and vaginal lavage samples were collected from 91 women with a history suggestive of recurrent vulvovaginal candidosis (RVVC), and with a suspected new attack of the condition. The specimens were cultured on Sabouraud and CHROMagar. Speciation of yeast isolates was made on the chromogenic agar by API 32C kits and by an atomized system (Vitek).

RESULTS

Forty-six (51%) women were positive for Candida from one or more of the samples. The introital cultures were positive in 43 (47%) women, both on Sabouraud and chromogenic agar. From the posterior vaginal fomix, 42 (46%) women were positive on the Sabouraud and 43 (47%) on chromogenic agar cultures, while the vaginal lavage cultures yielded Candida on those two media in 40 (44%) and 41 (45%) cases, respectively. Candida albicans was the most frequent species recovered, from 40 (87%) cases, followed by C. krusei in 4 (9%), C. glabrata in 2 (4%), and C. parapsilosis in one case. There was only one woman who had a mixed yeast infection, by C. albicans and C. krusei. There was only one discrepancy in the speciation as demonstrated by mean of chromogenic agar and API 32C kit.

CONCLUSIONS

Neither cultures of introital nor of vaginal lavage samples increases the detection rate of Candida in RVVC cases as compared to cultures of posterior vaginal fornix samples. Use of chromogenic agar is a convenient and reliable means to detect colonization by Candida and differentiate between C. albicans and non-albicans species.