Evaluation of Etest and macrodilution broth method for antifungal susceptibility testing of Candida sp strains isolated from oral cavities of AIDS patients

Drug-resistant oral candidiasis in patients with HIV infection: a systematic review and meta-analysis

BACKGROUND

Oral candidiasis (OC) is a prevalent opportunistic infection in patients with human immunodeficiency virus (HIV) infection. The increasing resistance to antifungal agents in HIV-positive individuals suffering from OC raised concerns. Thus, this study aimed to investigate the prevalence of drug-resistant OC in HIV-positive patients.

METHODS

Pubmed, Web of Science, Scopus, and Embase databases were systematically searched for eligible articles up to November 30, 2023. Studies reporting resistance to antifungal agents in Candida species isolated from HIV-positive patients with OC were included. Baseline characteristics, clinical features, isolated Candida species, and antifungal resistance were independently extracted by two reviewers. The pooled prevalence with a 95% confidence interval (CI) was calculated using the random effect model or fixed effect model.

RESULTS

Out of the 1942 records, 25 studies consisting of 2564 Candida species entered the meta-analysis. The pooled prevalence of resistance to the antifungal agents was as follows: ketoconazole (25.5%, 95% CI: 15.1-35.8%), fluconazole (24.8%, 95% CI: 17.4-32.1%), 5-Flucytosine (22.9%, 95% CI: -13.7-59.6%), itraconazole (20.0%, 95% CI: 10.0-26.0%), voriconazole (20.0%, 95% CI: 1.9-38.0%), miconazole (15.0%, 95% CI: 5.1-26.0%), clotrimazole (13.4%, 95% CI: 2.3-24.5%), nystatin (4.9%, 95% CI: -0.05-10.3%), amphotericin B (2.9%, 95% CI: 0.5-5.3%), and caspofungin (0.1%, 95% CI: -0.3-0.6%). Furthermore, there were high heterogeneities among almost all included studies regarding the resistance to different antifungal agents (I2 > 50.00%, P < 0.01), except for caspofungin (I2 = 0.00%, P = 0.65).

CONCLUSIONS

Our research revealed that a significant number of Candida species found in HIV-positive patients with OC were resistant to azoles and 5-fluocytosine. However, most of the isolates were susceptible to nystatin, amphotericin B, and caspofungin. This suggests that initial treatments for OC, such as azoles, may not be effective. In such cases, healthcare providers may need to consider prescribing alternative treatments like polyenes and caspofungin.

REGISTRATION

The study protocol was registered in the International Prospective Register of Systematic Reviews as PROSPERO (Number: CRD42024497963).

Resistance profiles to antifungal agents in Candida albicans isolated from human oral cavities: systematic review and meta-analysis

Aim

To identify the antifungal susceptibility profile of Candida spp. isolated from the human oral cavity was assessed with meta-analyses of observational studies that collected samples from the oral cavity of human subjects.

Material and methods

Isolated Candida albicans tested by E-test®; disk diffusion test; microdilution and macrodilution; Sensititre YeastOne; and/or FungiTest. Search strategies were conducted on the MEDLINE, Embase, CINAHL, Dentistry, and Oral Sciences, Central, Scopus, and LILACS databases, and gray literature sources. Articles were initially screened by title and then their abstracts. Articles that met the conditions for inclusion were read in full, followed by data extraction. A descriptive analysis was conducted of each study, and the data were tabulated. A first meta-analysis was conducted to assess the resistance of antifungals regardless of systemic comorbidities. An additional stratified analysis was conducted by systemic comorbidity groups for the outcome “resistance” to the antifungals.

Results

When not grouping Candida albicans isolates by systemic conditions, the lowest resistance rates to the antifungals tested were observed for amphotericin B, nystatin, flucytosine, and caspofungin. In contrast, the highest resistance rates were observed for miconazole and econazole. There was a high degree of heterogeneity and low resistance in general in all analyses, except for the “several associated comorbidities” group, which had high resistance rates.

Conclusions

Clinical C. albicans isolates had low antifungal resistance.

Clinical relevance

The presence of concomitant systemic comorbidities appears to be an essential factor that should be considered when evaluating resistance to antifungals for oral isolates.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00784-022-04716-2.

Antifungal Susceptibility Testing with Etest for Candida Species Isolated from Patients with Oral Candidiasis

Background

The necessity of performing antifungal susceptibility tests is recently increasing because of frequent cases of oral candidiasis caused by antifungal-resistant Candida species. The Etest (BioMerieux, Marcy l'Etoile, France) is a rapid and easy-to-perform in vitro antifungal susceptibility test.

Objective

The purpose of this study was to determine the minimal inhibitory concentrations (MICs) of antifungal agents by using the Etest for Candida species isolated from patients with oral candidiasis.

Methods

Forty-seven clinical isolates of Candida species (39 isolates of Candida albicans, 5 isolates of C. glabrata, and 3 isolates of C. tropicalis) were tested along with a reference strain (C. albicans ATCC 90028). The MIC end points of the Etest for fluconazole, itraconazole, voriconazole, and amphotericin B susceptibility were read after the 24-hour incubation of each isolate on RPMI 1640 agar.

Results

All Candida isolates were found susceptible to voriconazole and amphotericin B. However, all five isolates of C. glabrata were resistant to itraconazole, among which two isolates were also resistant to fluconazole.

Conclusion

This study revealed that the Etest represented a simple and efficacious method for antifungal susceptibility testing of Candida species isolated from oral candidiasis patients. Therefore, voriconazole and amphotericin B should be recommended as effective alternatives for the treatment of oral candidiasis.

Antifungal Susceptibility In Vitro Determined by the Etest(r) for Candida Obtained from the Oral Cavity of Irradiated and Elderly Individuals

This study aimed to evaluate the in vitro antifungal susceptibility of Candida species of head-and-neck-irradiated patients (Group 1), non-institutionalized (Group 2) and institutionalized elders (Group 3) using Etest(r) methodology. Candida was isolated from saliva and presumptively identified by CHROMagar Candida(r), confirmed by morphological criteria, carbohydrate assimilation (API 20C AUX(r)) and genetic typing (OPE 18). The collection was made from 29, 34 and 29 individuals (Groups 1, 2 and 3, respectively) with 67 isolates. Etest(r) strips (ketoconazole, itraconazole, fluconazole, amphotericin B and flucytosine) on RPMI (Roswell Park Memorial Institute) agar, on duplicate, were used to evaluate susceptibility. ATTC (American Type Culture Collection) 10231 (Candida albicans) was used as quality control. Among the 67 isolates of Candida species, most were susceptible to azoles, flucytosine and amphotericin B. None of the isolates showed resistance and dose-dependent susceptibility to amphotericin B. There were nine strains resistant to itraconazole, six to fluconazole and two to ketoconazole and ten dose-dependent, mainly to flucytocine. The highest MIC (minimum inhibitory concentration) to C. albicans, C. tropicalis, C. parapsilosis was 2.671 μg.mL-1, 8.104 μg.mL-1, 4.429 μg.mL-1, all for flucytosine. C. krusei and C. glabrata were associated with higher MIC for azoles and C. glabrata with higher MIC to flucytosine. In summary, susceptibility to all tested antifungal agents was evident. The isolates were more resistant to itraconazole and dose-dependent to flucytosine. A comparison of C. albicans in the three groups showed no outliers. Higher MIC was associated with C. krusei and C. glabrata.

Antifungal use influences Candida species distribution and susceptibility in the intensive care unit

OBJECTIVES

Antifungal prescription practices have changed over the last decade, and the impact of these changes is unclear. Our objective here was to evaluate the effect of antifungal drug use on the distribution and drug susceptibility of Candida spp. in a French intensive care unit (ICU).

METHODS

Antifungal drug use was measured as the number of defined daily doses per 1000 hospital days (DDDs/1000HD). The distribution of Candida spp. over a 6 year period (2004-09) and the MICs of antifungal drugs over 2007-09 were determined. Statistical analyses were performed to assess relationships between antifungal drug use, Candida spp. distribution and MIC changes over time.

RESULTS

Of 26,450 samples from 3391 patients, 1511 were positive for Candida spp. Candida albicans predominated (52.5%), followed by Candida glabrata (16.6%) and Candida parapsilosis (7.5%). C. parapsilosis increased significantly, from 5.7% in 2004 to 12.5% in 2009 (P = 0.0005). Caspofungin use increased significantly between 2004 (17.9 DDDs/1000HD) and 2009 (69.9 DDDs/1000HD) (P < 0.0001). Between 2007 and 2009, the increase in caspofungin use correlated significantly with the increase in caspofungin MICs displayed by C. parapsilosis (P < 0.0001) and C. glabrata (P = 0.03). Amphotericin B consumption changed over time and correlated with an increase in amphotericin B MICs for C. albicans (P = 0.0002) and C. glabrata (P = 0.0005). Significant declines occurred in both fluconazole use (P < 0.0001) and fluconazole MICs of C. albicans (P < 0.001)

CONCLUSIONS

Antifungal drug use in the ICU is associated with major changes in the distribution and drug susceptibility of Candida spp.

Correlation between Etest, disk diffusion, and microdilution methods for antifungal susceptibility testing of Candida species from infection and colonization

The correlation between the microdilution (MD), Etest (ET), and disk diffusion (DD) methods was determined for amphotericin B, itraconazole and fluconazole. The minimal inhibitory concentration (MIC) of those antifungal agents was established for a total of 70 Candida spp. isolates from colonization and infection. The species distribution was: Candida albicans (n=27), C. tropicalis (n=17), C. glabrata (n=16), C. parapsilosis (n=8), and C. lusitaniae (n=2). Non-Candida albicans Candida species showed higher MICs for the three antifungal agents when compared with C. albicans isolates. The overall concordance (based on the MIC value obtained within two dilutions) between the ET and the MD method was 83% for amphotericin B, 63% for itraconazole, and 64% for fluconazole. Considering the breakpoint, the agreement between the DD and MD methods was 71% for itraconazole and 67% for fluconazole. The DD zone diameters are highly reproducible and correlate well with the MD method, making agar-based methods a viable alternative to MD for susceptibility testing. However, data on agar-based tests for itraconazole and amphotericin B are yet scarce. Thus, further research must still be carried out to ensure the standardization to other antifungal agents.

Candiduria in a public hospital of São Paulo (1999-2004): characteristics of the yeast isolates

The study involved 100 yeast isolates, obtained from urine samples provided by a Public Pediatric Hospital of São Paulo, Brazil, from 1999 to 2004. The most frequent species was Candida albicans, followed by C. tropicalis, C. glabrata and C. parapsilosis. In regard to virulence, 97% of the isolates showed index 3 for proteinase and 63% index 2 for phospholipase. The most frequent killer biotypes were 511 and 888.

Antifungal susceptibility of bloodstream yeasts isolated at a public children’s hospital in Brazil: comparison of the Etest® and the AFST–EUCAST microdilution method

This study compared the minimum inhibitory concentration (MIC) results from the proposed standard methods of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antibiotic Susceptibility Testing (AFST–EUCAST) with the commercial system Etest® in the evaluation of susceptibility to flucytosine, fluconazole, itraconazole, voriconazole, and amphotericin B of 136 Candida spp. isolated from the blood of hospitalized children. The results presented a greater agreement among Etest® MICs ±2 log2 dilutions of AFST–EUCAST for fluconazole (98.1% and 96.3%) and voriconazole (100% and 100%) for Candida albicans and Candida parapsilosis . For Candida glabrata , the agreement was greater only for fluconazole (81.8%) and voriconazole (100%). For amphotericin B, the agreement between the methods was low for all species. The agreement percentage among the Etest® and AFST–EUCAST susceptibility profiles was high according to the MIC breakpoints recommended by the M27-A2 protocol for the majority of the yeasts, except for fluconazole and itraconazole against Candida tropicalis and for itraconazole against C. glabrata and Candida krusei . According to both methodologies, a great number of Candida spp. isolates showed an in vitro susceptibility to all evaluated antifungal agents. Overall, both procedures can be reliable techniques for susceptibility tests of yeasts, but the assessment of interlaboratory agreement and correlation of MICs by different methods with in vivo response are of great importance.