In vitro activities of new and conventional antimycotics against fluconazole-susceptible and non-susceptible Brazilian Candida spp. isolates

The substantial increase in the rate of azole resistant Candida spp. yeast infections has become a serious treatment problem requiring new and more active antifungal agents. In this study, the in vitro activities of ravuconazole and albaconazole were compared with those of amphotericin B, flucytosine, itraconazole and fluconazole against 162 Brazilian isolates of Candida spp. from which 48 isolates had previously shown lower susceptibility or resistance to fluconazole. Ravuconazole susceptibility ranged from 84.6% (Candida albicans) to 100% for other species and albaconazole MIC(90) was < or =1.0 microg ml(-1) for all the species emphasising the potent activity of these triazoles. To our knowledge this is the first study evaluating the susceptibility of C. dubliniensis to albaconazole.     

The Effect of Cilofungin (LY 121019) in Combination with Amphotericin B or Flucytosine Against Candida Species: Die Wirkung von Cilofungin (LY 121019) in Kombination mit Amphotericin B oder Flucytosin auf Candida-Arten

Cilofungin was combined with amphotericin B or flucytosine to determine if synergistic inhibition or killing occurred against 50 strains of various Candida species. Synergistic inhibition of growth occurred only once with amphotericin B and cilofungin and only 2 times with flucytosine and cilofungin. Synergistic killing occurred in 5 strains with the amphotericin B-cilofungin combination and in 7 strains with the flucytosine-cilofungin combination. Antagonism occurred frequently with both the amphotericin B-cilofungin and the flucytosine-cilofungin combinations.     

The Effect of Cilofungin (LY 121019) in Combination with Amphotericin B or Flucytosine AgainstCandidaSpecies

Cilofungin was combined with amphotericin B or flucytosine to determine if synergistic inhibition or killing occurred against 50 strains of various Candida species. Synergistic inhibition of growth occurred only once with amphotericin B and cilofungin and only 2 times with flucytosine and cilofungin. Synergistic killing occurred in 5 strains with the amphotericin B-cilofungin combination and in 7 strains with the flucytosine-cilofungin combination. Antagonism occurred frequently with both the amphotericin B-cilofungin and the flucytosine-cilofungin combinations.     

Oropharyngeal carriage of Candida species in HIV-infected patients in India

The present investigation represents the first study of oropharyngeal carriage of Candida and other yeasts in HIV-infected patients in India. One hundred and fifty HIV-positive patients were investigated by culturing their swish samples on plates of CHROMagar Candida. Ninety-eight patients (65.3%) were positive for Candida and four (2.7%) were positive for other yeasts. Among them, the first Indian C. dubliniensis isolate has been recovered. Molecular typing of selected C. albicans isolates by AP-PCR revealed two major genotypes based on the banding patterns. The susceptibilities of 30 Candida isolates to five antifungal agents including the new triazole voriconazole were determined in a micro-dilution test, according to the NCCLS protocol M 27. All the 22 C. albicans isolates were susceptible to five antimycotic agents (flucytosine, amphotericin B, fluconazole, voriconazole and itraconazole) except one isolate (VPCI-122), which was resistant to flucytosine (MIC > or = 64 mg l-1). The azole-resistant isolates reported here endorse the role of antifungal susceptibility testing whenever antifungal treatment with azoles is planned.     

Antifungal susceptibility and genotypes of Candida albicans strains from patients with vulvovaginal candidiasis

Studies of the genetic diversity of Candida albicans strains and the correlation between the antifungal susceptibility and gene diversity of C. albicans were carried out and the results were found to be inconsistent. To investigate antifungal susceptibility and genotypes of C. albicans strains from patients with vulvovaginal candidiasis (VVC), the genotypes of C. albicans in patients with VVC were studied using a recently developed polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) of CAI microsatellite method and antifungal susceptibility was tested using E-test methods. Twenty-six genotypes were identified from 89 strains of C. albicans isolated from patients with VVC. Candida albicans isolates were susceptible to amphotericin B, flucytosine, ketoconazole and fluconazole. The dominant genotypes (A, B, C, D) account for 69.7% (62/89) of C. albicans . The resistant rate of C. albicans genotype B to itraconazole (ITR) and that of C. albicans non-genotype B strains were 66.7% (14/21) and 4.4% (3/68) respectively at P  < 0.05. We concluded that C. albicans genotype B from patients with VVC was more resistant to ITR.     

In vitro interactions between amphotericin B and other antifungal agents and rifampin against Fusarium spp.

Fusarium species are common hyaline soil saprophytes and plant pathogens that are opportunistic fungal pathogens of immunocompromised patients. The treatment for fusariosis remains uncertain with an unfavourable prognosis; new possibilities for treatment, such as various synergistic drug interactions, must be uncovered. In this study, we evaluated the in vitro interactions of amphotericin B with caspofungin, ketoconazole, 5‐flucytosine, itraconazole, miconazole, rifampin, fluconazole, terbinafine and voriconazole against isolates of Fusarium spp. using the chequerboard method with interactions evaluated by fractional inhibitory concentration indices. The highest percentages of synergistic interactions were observed for the combinations of amphotericin B and caspofungin (68.7%), amphotericin B and rifampin (68.7%), amphotericin B plus 5‐flucytosine (59.3%) and amphotericin B with voriconazole (37.5%). The pattern of susceptibility to antifungal agents among Fusarium species and their consequence on the effects of drug combinations are also discussed.     

Prevalence of Candida dubliniensis among germ tube-positive yeasts recovered from the respiratory specimens in HIV-negative patients

The present investigation was conducted to identify Candida dubliniensis, from respiratory specimens, recovered from HIV-negative patients. Over a 7-month period, 75 germ tube and chlamydospore-positive yeasts were screened for C. dubliniensis, using a variety of phenotypic characteristics. Their identification was based on sugar assimilation reactions using API 20 C Aux. A total of seven (9%) isolates recovered from sputum, bronchial lavage and nasopharyngeal aspirate were identified as C. dubliniensis. All the isolates were susceptible to amphotericin B. One isolate each showed resistance to fluconazole and ketoconazole, and two were resistant to itraconazole. A significantly high percentage (43%) of C. dubliniensis showed resistance to flucytosine.     

In vitro susceptibilities of Malaysian clinical isolates of Cryptococcus neoformans var. grubii and Cryptococcus gattii to five antifungal drugs

The in vitro susceptibilities of Malaysian clinical isolates of Cryptococcus neoformans var. grubii and C . gattii to five antifungal drugs (amphotericin B, flucytosine, fluconazole, itraconazole and ketoconazole) were determined using the Etest method. None of the Malaysian isolates was resistant to amphotericin B and ketoconazole. Isolates resistant to flucytosine, fluconazole and itraconazole were observed in this study. Minimum inhibition concentrations (MICs) of > or = 32 microg ml(-1) against flucytosine, > or = 64 microg ml(-1) against fluconazole and > or = 1 microg ml(-1) against itraconazole were noted in four (8.3%), two (4.2%) and one (2.1%) isolates respectively. There was no significant difference in the MICs for both Cryptococcus species (P > 0.05), indicating that C. gattii was as susceptible as var. grubii to all the antifungal drugs tested. No significant difference in the MICs for both Cryptococcus species collected from 1980 to 1990 and 2002 to 2004 were observed (P > 0.05).     

Microbial profile and drug resistance of Candida strains isolated from the blood of children: an 11-year study

The latest observations indicate a continuous increase in the frequency of fungal infections, particularly in hospital patients, accompanied by changes in both the profile of the isolated strains and their drug susceptibility. The objective of this study was to evaluate the trend in the incidence of candidaemia and susceptibility of antifungal drugs in the Polish Mother's Memorial Hospital over an 11-year period. Blood samples taken from the hospitalised children were sent to the Department of Clinical Microbiology for diagnostic purposes. A total of 195 Candida strains were isolated: 47.7% Candida albicans and 52.3% non- albicans . Candida parapsilosis was isolated in 65.7% of non- albicans strains. The prevalence of Candida spp. decreased from 16.9–20.5% in the years 1996–1997 to 3.1–2.1% in the years 2005–2006. In the years 2000–2005, non- albicans strains were more prevalent. All C. albicans strains were susceptible to amphotericin B, 2.94% of non -C. albicans strains were semisusceptible to amphotericin B, 98.92% of C. albicans and 85.29% of non- albicans strains were susceptible to 5-fluorocytosine. Candida spp. strains are predominant pathogens in fungaemia in children in our hospital. Over the last few years, C. albicans have been replaced by non- albicans strains (predominantly C. parapsilosis ), which exhibit a higher level of drug resistance. The number of Candida spp. isolated from blood decreased during the 11-year study.     

Comparison of Broth Dilution and Semisolid Agar Dilution for In Vitro Susceptibility Testing of Cryptococcus neoformans

Summary

We compared the in vitro activity of amphotericin B, flucytosine, itraconazole, fluconazole, ketoconazole and miconazole against 18 strains of Cryptococcus neoformans by using two methods: microbroth dilution and semisolid agar dilution.

By both of the methods minimum inhibitory concentrations (MICs) showed a wide range for all antifungal agents but not for amphotericin B. Statistically significant differences between the two methods were observed only with amphotericin B and flucytosine, p = 0.048 and p = 0.045 respectively.

Our study suggests that azole susceptibility testing for C. neoformans may be performed by the broth microdilution as well as the semisolid agar test. The choice of the method when testing amphotericin B and flucytosine is more problematic.     

In vitro antifungal susceptibility of clinical isolates of Candida spp. from hospitalized patients

A total of 122 Candida spp. strains, isolated from a group of 100 patients hospitalized in the Santa Casa de Misericordia of Belo Horizonte were assayed for in vitro susceptibility to amphotericin B, fluconazole, itraconazole, ketoconazole and flucytosine using a microbroth technique proposed by the National Committee for Clinical Laboratory Standards. In this study large variations were observed among minimum inhibitory concentration values depending on the species tested. The statistical analysis (Kruskal-Wallis test) showed that itraconazole and flucytosine were the more efficient antifungal drugs for most of species, and amphotericin B and fluconazole were the least efficient.     

Activity of terbinafine against serious fungal pathogens

Although primarily indicated for dermatophyte infections, the allylamine terbinafine is active in vitro against a broad spectrum of filamentous and dimorphic fungi, in most cases with a primary fungicidal action. Using the standard NCCLS M27-A assay, recent studies confirmed the high activity of terbinafine against dematiaceous fungi and other medically important moulds such as Aspergillus and Penicillium marneffei. Terbinafine displayed a geometric mean MIC of 1.4 micrograms/ml against Candida albicans (n = 259) and has significant in vitro activity against other species of Candida, Cryptococcus, Trichosporon and Blastoschizomyces. As an approach to treatment of refractory infections, interactions of terbinafine with azoles and other agents are being investigated. Terbinafine was synergistic with azoles (and in some cases amphotericin B) against Candida species, Trichosporon beigelii, Aspergillus species, Pseudallescheria boydii and Scopulariopsis brevicaulis, some of which were unresponsive to any drug used singly. Terbinafine combined with fluconazole showed potent synergy against fluconazole- and multidrug-resistant C. albicans isolates. In conclusion, recent in vitro data suggest that terbinafine, either alone or in combination with other antifungal drugs, has potential in the therapy of a range of more severe fungal infections, in addition to its current widespread use against dermatomycoses.     

Epidemiology and antifungal susceptibility patterns of Candida isolates from Greek women with vulvovaginal candidiasis

Vulvovaginal candidiasis (VVC) is a common infection of the genital tract affecting millions of women worldwide. Data on epidemiological trends of VVC in Greece are scarce. This study was undertaken to evaluate the prevalence of VVC among symptomatic women in Crete, Greece, identify the Candida species involved and determine their susceptibility to antifungals. Over a 6‐year period (2012‐2017), 10 256 symptomatic women with vaginitis were evaluated. Isolation of yeasts was performed on Sabouraud dextrose agar with chloramphenicol, and the isolates were identified using the API 20 C AUX and/or the Vitek 2 YST card. Susceptibility of the isolates to amphotericin, fluconazole, voriconazole and flucytosine was determined by the Vitek 2 automated system. The results were interpreted according to Clinical and Laboratory Standards criteria. Vaginal swab cultures of 1217 (11.9%) women yielded Candida species. Recurrent VVC was documented in 62 (5.1%) of them. Candida albicans was the most frequently isolated species (75.6%), followed by Candida glabrata (13.6%). Overall, resistance rates to amphotericin B, fluconazole, voriconazole and flucytosine were 0.2%, 6.6%, 1.4% and 2.1%, respectively. Fluconazole resistance of C. albicans significantly increased in the second period of the study (2015‐2017) (P = 0.031). This study demonstrated that VVC is a common infection among women in our region, with C. albicans being the predominant species involved. Although resistance to antifungals was infrequent, resistance to fluconazole among C. albicans isolates was found to significantly increase with time. Continued surveillance of changes in species distribution and susceptibility to antifungals are necessary to guide treatment.     

In-vitro activity of the synthetic protegrin IB-367 alone and in combination with antifungal agents against clinical isolates of Candida spp

The in vitro activity of the peptide IB-367, alone or combined with either fluconazole (FLU) or amphotericin B (AMB), was investigated against 25 Candida isolates belonging to five species. IB-367 minimum inhibitory concentrations (MICs) ranged from 2.0 to 32 microg/ml and it was active against both FLU-susceptible and - resistant isolates. A rapid fungicidal activity was observed. Synergism was documented in 41.6% and 44% of IB-367/FLU and IB-367/AMB interactions, respectively. Antagonism was never observed. The broad antifungal activity and the positive interactions with AMB and FLU suggest that IB-367 represents a promising candidate against infections due to Candida spp.     

Antifungal activity of miconazole against recent Candida strains

Miconazole (MICON) has long been used for the topical treatment of mucosal candidiasis. However, the preponderance of MICON susceptibility data was generated before standard methodology was established, and prior to the emergence of fluconazole (FLU)‐resistant strains. The objective of this study was to determine the antifungal activity of MICON and comparators against recent clinical isolates of Candida spp. using standard Clinical and Laboratory Standards Institute methodology. One hundred and fifty isolates, consisting of 25 strains each of Candida albicans, C. krusei, C. glabrata, C. tropicalis, C. parapsilosis and C. dubliniensis, were tested. Of these, twenty‐two strains were known to be FLU‐resistant. Minimum inhibitory concentrations (MICs) were determined for MICON, amphotericin B (AM), caspofungin (CAS), clotrimazole (CLOT), FLU, itraconazole (ITRA), nystatin (NYS) and voriconazole (VOR). MICON demonstrated potent inhibitory activity against all of the strains tested. The MIC₉₀ for MICON was 0.12 μg ml^?1 against FLU‐susceptible strains, which was comparable to that of AM, CAS, CLOT, ITRA and VOR. The MICON MIC₉₀ against FLU‐resistant strains was 0.5 μg ml^?1, which was 12‐fold lower than the FLU MIC₉₀. Our study showed that MICON possesses potent activity against all of the Candida isolates tested, including those with known FLU resistance. This indicates that recent clinical isolates remain susceptible to this antifungal and that MICON could be used as first‐line treatment for oropharyngeal candidiasis.     

Susceptibility to antifungal agents of Candida species isolated from paediatric and adult patients with haematological diseases

Summary The susceptibility to six antifungals: amphotericin B (AMF), 5-fluorocytosine (5-F), miconazole (MIK), ketoconazole (KET), fluconazole (FLU) and itraconazole (ITR) was tested among 206 Candida spp. isolated from paediatric and adult patients with haematological malignancies. To determinate the susceptibility the commercial microdilution method Fungitest (Bio-Rad, France) was used. The strains were classified as susceptible, intermediate susceptible, or resistant on the base of the growth in following breakpoint concentrations of particular drugs: 2 and 8 microg ml(-1) for AMF, 2 and 32 microg ml(-1) for 5-F, 0.5 and 8 microg ml(-1) for MIK, 0.5 and 4 microg ml(-1) for KET and ITR, and 8 and 64 microg ml(-1) for FLU. The highest activity to overall species showed AMF (only one resistant strain) and 5-F (85% susceptible strains). Most of C. albicans isolates were susceptible to tested azoles. The percentages of C. albicans resistant to FLU, ITR, KET and MIK were 4, 11, 8, and 0.8%, respectively. The less susceptible to azoles were C. glabrata and C. krusei (14% and 44% isolates resistant to FLU). A non-albicans Candida isolated from adult patients receiving KET prophylaxis was more frequently resistant to FLU than isolates from patients without previous exposure to azoles (P < 0.05). We did not observe differences in the susceptibility of Candida strains isolated from children compared with those from adults.     

In vitro antifungal susceptibilities of isolates of Candida spp. and Aspergillus spp. from China to nine systemically active antifungal agents: data from the SENTRY antifungal surveillance program, 2010 through 2012

We report the in vitro activity of nine systemically active antifungal agents against 237 contemporary clinical isolates of yeast and moulds obtained from 13 laboratories in China during 2010 through 2012. Susceptibility testing was performed using CLSI methods. Sequencing of fks hot spots was performed for echinocandin non‐wild‐type (WT) strains. Isolates included 220 from eight species of Candida, 15 from four species of Aspergillus and one isolate each of Rhodotorula mucilaginosa and Trichosporon asahii. Resistance to amphotericin B (0.0%), flucytosine (0.0–1.7%) and the echinocandins (0.0–3.4%) was distinctly uncommon among C. albicans, C. parapsilosis, C. tropicalis, C. glabrata and C. pelliculosa. Three C. albicans isolates showed resistance to echinocandins and one harboured a mutation in HS1 of fks1. Resistance to the azoles was much more common with resistance to fluconazole, voriconazole and posaconazole detected among isolates of C. glabrata and C. tropicalis. Both C. parapsilosis and C. pelliculosa exhibited decreased susceptibility to fluconazole. Amphotericin B, the mould‐active azoles and the echinocandins were all quite active against isolates of A. fumigatus and A. flavus. Consistent with previous studies from China, resistance to fluconazole is prominent among Candida spp. isolates in this country.     

Yeasts species distribution in Neonatal Intensive Care Units in northeast Argentina

The aim of this study was to determine the distribution and antifungal susceptibility profile of yeast species isolated from neonates in Neonatal Intensive Care Units (NICU) in northeast of Argentina. With this purpose 92 strains isolated from 25 blood stream cultures, 20 venous catheters, 23 suprapubic aspirations and 24 rectal swabs were studied. Candida albicans and C. parapsilosis appeared with similar frequencies (36%) in blood stream isolates. Candida parapsilosis (50%) was the most frequent catheters colonizer and C. tropicalis (54.2%) was the most frequent yeast associated with gastrointestinal tract colonization. Candida krusei, C. glabrata and Trichosporon cutaneum appeared with a very low frequency. A high rate of susceptibility to amphotericin B, fluconazole, and itraconazole was observed.     

In vitro susceptibility of Cryptococcus neoformans clinical isolates from Egypt to seven antifungal drugs

The in vitro susceptibility of 29 clinical isolates of Cryptococcus neoformans to fluconazole, miconazole, itraconazole, ketoconazole, flucytosine, nystatin and amphotericin B was tested by broth and colorimetric microdilution methods. Most of the isolates showed uniform patterns of susceptibility to the used antifungal agents. Only three isolates exhibited resistance [fourfold or greater rise in the minimum inhibitory concentrations (MICs)] to the tested antifungal drugs. The MIC50 and MIC90 were 0.5-8 mg l(-1) for 5-flucytosine, 0.2-8.25 mg l(-1) for nystatin, 0.5-16 mg l(-1) for fluconazole and 0.2-12.5 mg l(-1) for miconazole. However, MIC50 and MIC90 were in narrow range for the clinical yeast isolates in both methods used and showed 0.5-1 mg l(-1) for amphotericin B and 0.016-0.25 mg l(-1) for both ketoconazole and itraconazole. The combination of fluconazole plus flucytosine showed greater synergistic and fungicidal activity compared with that of fluconazole plus amphotericin B or the use of individual drugs.