Azole resistance in neonatal intensive care units in Argentina

The aim of this study was to determine the antifungal susceptibility profile and to detect resistant strains of yeast species isolated from neonates in Intensive Care Units. 92 strains isolated from 25 bloodstream cultures, 20 venous catheters, 23 suprapubic aspirations and 24 rectal swabs were studied. A Candida glabrata strain resistant to fluconazole was detected. Candida krusei appeared with its inherent resistance to fluconazole and showed cross-resistance to itraconazole. Two Candida albicans strains were resistant to azoles, one to itraconazole and the other to fluconazole with a high minimum inhibitory concentration (MIC) for itraconazole. All Candida tropicalis strains were susceptible to fluconazole but two of them showed resistance to itraconazole. The detection of resistant strains in neonates whom had not received previous antifungal therapy is noteworthy. The variations in the epidemiology of fungal infections observed and the antifungal resistance detected emphasize the importance of performing a regular surveillance to observe and to assess them.     

Species distribution and antifungal susceptibility of blood Candida isolates at a tertiary hospital in southern Taiwan, 1999–2006

The aim of this study was to evaluate the incidence of candidaemia, consumption of fluconazole and susceptibility of blood Candida isolates at a tertiary hospital. From January 1999 to September 2006, all candidaemic episodes were identified and available strains were evaluated for the susceptibilities of antifungal agents. Annual defined daily doses of antifungal agents were collected. There had been 909 Candida isolates detected from the bloodstream of 843 patients during the study period. Among them, 740 isolates were available for the susceptibilities of antifungal agents. The incidence density of candidaemia was 28 episodes per 10 000 patient‐days. Species distribution of 909 isolates did not vary annually, but varied greatly in the units of the hospital. Candida parapsilosis was the more prominent (30.1%) isolate in the paediatric units, where C. tropicalis and C. glabrata were less common (12.3% and 1.4% respectively). Resistance rates for itraconazole, fluconazole and voriconazole were 6.9%, 3.8% and 3.8% respectively. There were 25 (3.4%) isolates resistant to amphotericin‐B. Although fluconazole usage increased over time (r² = 0.45; P = 0.07), fluconazole resistance did not increase accordingly (P = 0.33). In our institution in which the incidence of candidaemia was high, fluconazole resistance among blood Candida isolates remained rare.     

Fluconazole,Itraconazole and Ketoconazole In- Vitro Activity. A Comparative Study

Summary

We compared in-vitro activity of fluconazole, itraconazole and ketoconazole by evaluating their Minimal Inhibitory Concentrations (MICs) for 100 fungal strains isolated from different biological specimens of ARC/AIDS patients. A semisolid agar medium was used: this method is suitable for testing molds and yeasts, and can be applied to all azole antifungal drugs. Fluconazole had higher MICs than two other tested drugs, especially for Candida krusei strains; however it never had a MIC higher than 40mg/l.

Itraconazole and ketoconazole had MICs higher than 40mg/l for one Cryptococcus neoformans strain. There were no significant differences for itraconazole and ketoconazole among the tested strains.     

Azole resistance in Candida albicans from animals: Highlights on efflux pump activity and gene overexpression

This study investigated potential mechanisms of azole resistance among Candida albicans from animals, including efflux pump activity, ergosterol content and gene expression. For this purpose, 30 azole‐resistant C. albicans strains from animals were tested for their antifungal susceptibility, according to document M27‐A3, efflux pump activity by rhodamine 6G test, ergosterol content and expression of the genes CDR1, CDR2, MDR1, ERG11 by RT‐qPCR. These strains were resistant to at least one azole derivative. Resistance to fluconazole and itraconazole was detected in 23 and 26 strains respectively. Rhodamine 6G tests showed increased activity of efflux pumps in the resistant strains, showing a possible resistance mechanism. There was no difference in ergosterol content between resistant and susceptible strains, even after fluconazole exposure. From 30 strains, 22 (73.3%) resistant animal strains overexpressed one or more genes. From this group, 40.9% (9/22) overexpressed CDR1, 18.2% (4/22) overexpressed CDR2, 59.1% (13/22) overexpressed MDR1 and 54.5% (12/22) overexpressed ERG11. Concerning gene expression, a positive correlation was observed only between CDR1 and CDR2. Thus, azole resistance in C. albicans strains from animals is a multifactorial process that involves increased efflux pump activity and the overexpression of different genes.     

Etiology of fungaemia and catheter colonisation in Argentinean paediatric patients

Yeast strains obtained from blood cultures and catheters from intensive care units (ICU) and hospitalised oncology paediatrics were studied. Yeast were the first cause of catheter colonisation (51/627), and the third cause of bloodstream infection (44/6065). In catheter, the most frequent species were Candida albicans (34%), C. parapsilosis (27.7%) and C. tropicalis (15%). In blood, C. albicans (40.8%), C. parapsilosis (26.6%), C. tropicalis (15%). Malassezia furfur and Malassezia sympodialis were isolated from catheters from ICU patients. All isolates were susceptible to amphotericin B, 88.8% to itraconazole and 91.9% to fluconazole. Candida albicans and C. tropicalis strains resistant to fluconazole and itraconazol were detected. These results reveal a change in the predominant role of C. albicans as cause of candidemia in hospitalised children and the emergence of antifungal resistant species. These variations emphasise the importance of performing a permanent surveillance to observe and assess them.     

Neonatal invasive candidiasis in Tunisian hospital: incidence, risk factors, distribution of species and antifungal susceptibility

The aim of our study was to assess epidemiological features of neonatal invasive candidiasis in Farhat Hached hospital of Sousse, Tunisia, including incidence, risk factors, mortality, species distribution and antifungal susceptibility. Laboratory data from 1995 to 2010 and medical records of 127 invasive candidiasis cases were reviewed. We tested the susceptibility of 100 Candida sp isolates by using ATB fungus^®3 and to fluconazole by using E‐test^® strips. A total of 252 cases of neonatal invasive candidiasis occurred over the study period. The incidence increased 1.8‐fold from 1995 to 2006 and decreased fourfold from 2007 to 2010. Candida albicans was the predominant species up to 2006 and a shift in the species spectrum was observed with increase of the non‐albicans species mainly C. parapsilosis. The agreement between the ATB Fungus^® and the E‐test^® for determining fluconazole susceptibility was high. All tested isolates were susceptible to fluconazole, flucytosine, amphotéricine B and voriconazole and the itraconazole resistance rate was 5%. The mortality rate was 63%. The invasive candidiasis incidence increased from 1995 to 2006 and decreased from 2007 to 2010. The spectrum of Candida species and the lack of fluconazole‐resistant strains argue for the usefulness of fluconazole as an empiric treatment.     

Cross‐resistance to fluconazole induced by exposure to the agricultural azole tetraconazole: an environmental resistance school?

This study aimed to investigate the influence of tetraconazole and malathion, both used in agricultural activities, on resistance to fluconazole, itraconazole and voriconazole in Candida parapsilosis ATCC 22019. The susceptibility to tetraconazole, malathion, fluconazole, itraconazole and voriconazole, through broth microdilution. Then, 12 independent replicates, were separated and exposed to four treatment groups, each one containing three replicates: G1: tetraconazole; G2: malathion; G3: fluconazole (positive control); G4: negative control. Replicates from G1, G2 and G3, were exposed to weekly increasing concentrations of tetraconazole, malathion and fluconazole, respectively, ranging from MIC/2 to 32 × MIC, throughout 7 weeks. The exposure to tetraconazole, but not malathion, decreased susceptibility to clinical azoles, especially fluconazole. The tetraconazole‐induced fluconazole resistance is partially mediated by the increased activity of ATP‐dependent efflux pumps, considering the increase in antifungal susceptibility after the addition of the efflux pump inhibitor, promethazine, and the increase in rhodamine 6G efflux and CDR gene expression in the G1 replicates. Moreover, MDR expression was only detected in G1 and G3 replicates, suggesting that MDR pumps are also involved in tetraconazole‐induced fluconazole resistance. It is noteworthy that tetraconazole and fluconazole‐treated replicates behaved similarly, therefore, resistance to azoles of clinical use may be a consequence of using azoles in farming activities.     

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.     

Emergence of Resistance to Amphotericin B and Triazoles in Candida glabrata Vaginal Isolates in a Case of Recurrent Vaginitis

Abstract

Emergence of resistance to triazoles and amphotericin B in Candida glabrata vaginal isolates is documented by Etest. During the 18-month follow-up of a case of vaginitis, 14 consecutive isolates of C. glabrata were examined. The isolates exhibited development of in vitro resistance beginning with itraconazole (>32 μg/ml), followed by fluconazole (>256 μg/ml), amphotericin B (>32 μg/ml), and voriconazole (>32 μg/ml). The DNA sequence analyses and finger printing of the isolates strongly suggest that our patient remained colonized with a single strain. The report underscores the propensity of C. glabrata to acquire resistance during antifungal therapy and the importance of susceptibility testing in the management of infections caused by this species.     

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 susceptibility of 545 isolates of Candida spp. to four antifungal agents

Summary. The in vitro susceptibility to amphotericin B, fluconazole, itraconazole and ketoconazole of 545 Candida strains from patients treated at the University Hospital of the Canaries was determined by means of a microdilution test. The distribution of the species was as follows: Candida albicans (342), Candida tropicalis (70), Candida glabrata (68), Candida parapsilosis (65). Of Candida albicans isolates, 8.5% and 7.6% showed resistance to itraconazole and fluconazole respectively. Of C. tropicalis isolates 34.3%, 27.1% and 2.9% were resistant to itraconazole, fluconazole and ketaconazole respectively. For C. glabrata , 10.3% and 4.4% of the isolates under study demonstrated resistance to fluconazole and itraconazole respectively. Only 4.6% and 1.5% of C. parapsilosis isolates demonstrated resistance to fluconazole and itraconazole respectively. C. tropicalis was the most resistant strain and C. parapsilosis the most sensitive. The greatest percentages of resistance in vitro were seen with the triazoles.
Zusammenfassung. Es wurde die Empfindlichkeit von 545 Candida -Stämmen für Amphotericin B, Fluconazol, Itraconazol und Ketoconazol in vitro in einem Mikrodilutionstest bestimmt. Bei den Stämmen handelte es sich um Isolate von Patienten, die in der Universitäts-Klinik der Kanarischen Inseln behandelt worden waren. Das Untersuchungsgut war wie folgt verteilt: 342 Candida albicans , 70 C. tropicalis , 68 C. glabrata , 65 C. parapsilosis. Bei C. albicans waren 8.5% gegen Itraconazol und 7.6% gegen Fluconazol resistent. Bei C. tropicalis wurden 34.3% resistent gegenüber Itraconazol befundet, 27.1% gegen Fluconazol und 2.9% gegen Ketoconazol. Bei C. glabrata waren 10.3% resistent gegen Fluconazol und 4.4% gegen Itraconazol. Candida parapsilosis wurde zu 4.6% gegen Fluconazol und zu 1.5% gegen Itraconazol als resistent befundet. Somit erwies sich C. tropicalis als die resistenteste und C. parapsilosis als die sensibelste Art.     

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.     

Fluconazole and itraconazole susceptibilities of Candida spp. isolated from oropharyngeal specimens and blood cultures of paediatric haematology/oncology patients

This study examined the in vitro susceptibilities to fluconazole and itraconazole of isolates of Candida spp. from surveillance oropharyngeal specimens and blood cultures from paediatric patients with malignancy. The species distribution of 100 isolates from oropharyngeal specimens was C. albicans 86%, C. glabrata 7%, C. lusitaniae 4%, C. parapsilosis 2% and C. tropicalis 1%. From a total of nine isolates from blood cultures the species distribution was C. albicans 33.3%, C. parapsilosis 33.3 % and C. guilliermondii 33.3%. Only three of the oropharyngeal isolates were resistant to fluconazole (MIC > or = 64 mg l(-1)) and only two were resistant to itraconazole (MIC > or = 1 mg l(-1)). None of the blood culture isolates was resistant to either agent. At this centre, C. albicans is the predominant species from oropharyngeal specimens, but non-albicans Candida species predominate in blood cultures. Although resistance to fluconazole and itraconazole is rare at present, continued surveillance is warranted to monitor trends in species distribution and antifungal susceptibility.     

The antifungal properties of chicken egg cystatin against Candida yeast isolates showing different levels of azole resistance

The increasing incidence of fungal infections together with the emergence of strains resistant to currently available antifungal drugs calls for the development of new classes of antimycotics. Naturally occurring antifungal proteins and peptides are of interest because of low toxicity, immunomodulatory potential and mechanisms of action distinct from those of currently available drugs. In this study, the potent antifungal activity of cystatin, affinity‐purified from chicken egg white (CEWC), against the most frequent human fungal pathogens of the genus Candida was identified and characterised. CEWC inhibited the growth of azole‐sensitive Candida albicans isolates with minimal inhibitory concentration (MIC) values ranging from 0.8 to 3.3 μmol l^?1, a potency comparable with those of fluconazole and histatin 5, the antimicrobial peptide of the human saliva. Similarly to histatin 5, CEWC activity was not compromised in azole‐resistant isolates overproducing the multidrug efflux transporters Cdr1p and Cdr2p and did not antagonise fluconazole or amphotericin B. CEWC had candidacidal activity, as revealed by the time‐kill assay, and, similarly to histatin 5, completely inhibited the growth at supra‐MIC concentrations. This was in contrast to the fungistatic effect and trailing growth observed with fluconazole. CEWC inhibited the growth of Candida parapsilosis and Candida tropicalis at similar concentrations, whereas Candida glabrata was more resistant to CEWC.     

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.     

The prevalence of Candida onychomycosis in Southeastern Serbia from 2011 to 2015

Despite the increasing of onychomycosis caused by Candida spp., in referent literature, there is still data insufficiency about this nail infection. The objectives of this retrospective study were to determine epidemiological characteristics of Candida onychomycosis, the antifungal susceptibility of isolated species in vitro, and to compare the results of antifungal susceptibility testing with conducted treatment in period from 2011 to the end of March 2015. Out of 761 patients who were underwent clinical and mycological examinations, 137 had Candida species isolated from nails. The dominant species was Candida albicans (C. albicans) (36.59%) followed by C. parapsilosis (23.78%), C. krusei (9.76%), and C. guilliermondii (6.71%). Antifungal susceptibility in vitro testing showed good susceptibility to antimycotics, except C. krusei, which was resistance to fluconazole (FCZ) and isolates of C. tropicalis and C. glabrata which were dose dependent to itraconazole (ITZ) and fluconazole. Evaluation of medical histories determined that combined therapy, which included pulsed systemic regimen of ITZ with topical application of clotrimazole, had better clinical outcomes regarding the proscribed only topical application of clotrimazole. Multidisciplinary approach of dermatologists and mycologists is required in solving the problem of onychomycosis, which is the dominant nail disease.     

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.     

In Vitro Susceptibility of Nondermatophyte Molds Isolated from Onycomycosis to Antifungal Drugs

Abstract

Despite many advances in antifungal drug development and therapy, onychomycosis due to nondermatophyte molds (NDM) remains difficult to treat. Using a reference microdilution method (CLSI M38-A), the antifungal susceptibility to bifonazole, ciclopiroxolamine, fenticonazole, itraconazole, ketoconazole, miconazole, terbinafine and tioconazole of 64 molds isolated from toenail onychomycosis was studied. All the strains showed good susceptibility to ciclopiroxolamine. Aspergillus had excellent susceptibility to itraconazole followed by miconazole, ketoconazole, tioconazole, fenticonazole and terbinafine. The isolated species had variable susceptibility to bifonazole. Scopulariopsis had wide MIC ranges for all antifungal drugs tested except ciclopiroxolamine. Fusarium and Acremonium had reduced susceptibility to antifungal drugs tested. Nevertheless, some strains show low MICs for ketoconazole, miconazole and tioconazole.

Studies to evaluate In Vitro susceptibility testing using CLSI methods for NDM onychomycosis should be undertaken.     

Oral yeast carriage in HIV-infected and non-infected populations in Rosario, Argentina

The objectives of the present study were: (i) to assess the frequency of oral colonisation by Candida species in HIV-positive patients and to compare it with a population of HIV-negative individuals, (ii) to determine the prevalence of C. dubliniensis in both populations and (iii) to determine the susceptibility of C. dubliniensis and other Candida species isolated from HIV-positive patients to the most commonly used antifungal agents. Oral samples were obtained from 101 HIV-positive and 108 HIV-negative subjects. For yeast identification, we used morphology in cornmeal agar, the API 20C Aux, growth at 45 °C, d -xylose assimilation, morphology in sunflower seed agar and PCR. The frequency of isolation of Candida in HIV-positive patients was: C. albicans , 60.7%; C. dubliniensis , 20.2%; C. glabrata , 5.6%; C. krusei , 5.6%; C. tropicalis , 4.5%; others, <5%. The frequency of isolation of Candida in HIV-negative patients was: C. albicans , 73.9%; C. tropicalis , 15.5%; C. dubliniensis , 2.1%; C. glabrata , 2.1%; C. parapsilosis , 2.1%; others, <5%. The oral colonisation by yeast in the HIV-positive patients was higher than that in the HIV-negative subjects. The susceptibilities of 42 Candida isolates to three antifungal agents were determined. All isolates of C. dubliniensis were susceptible to fluconazole, although several individuals had been previously treated with this drug. Out of the 42 Candida isolates, 10 presented resistance to fluconazole and 10 to itraconazole. The presence of Candida species, resistant to commonly used antifungal agents, represents a potential risk in immunocompromised patients.     

Sertaconazole: In-Vitro Antifungal Activity Against Vaginal and Other Superficial Yeast Isolates

Abstract

The in vitro susceptibilities of 183 clinical yeast isolates to sertaconazole (STZ) were compared to their susceptibilities to clotrimazole (CTZ), econazole (ECZ), ketoconazole (KTZ), miconazole (MNZ), fluconazole (FLZ), itraconazole (ITZ), tioconazole (TCZ), amphotericin B (AMB) and flucytosine (5FC) by using a commercial agar diffusion method. Strains were isolated from vaginal and other superficial clinical samples (18 species of Candida and five strains belonging to other yeast genera). Only one strain (0.5%) was resistant to STZ out of 87.4% of susceptible strains (n=160). The percentage of susceptible strains was higher than those obtained with the other agents evaluated and the percentage of resistant strains was lower than for most of the other antifun-gals. The pattern of susceptibility of C. albicans to STZ, TCZ, ITZ and CLZ was similar and superior to the pattern of susceptibility of this species to MNZ, ECZ, FLZ, 5FC and KTZ. C. dubliniensis was more susceptible to STZ, MNZ, MNZ, FLZ, ITZ, CLZ than to TCZ, ECZ, 5FC, AMB or KTZ. Ten susceptible strains to STZ were resistant to FLZ and one strain was resistant to ITZ. The overall antifungal activity of STZ in vitro against a wide range of clinically important yeasts from vaginal and cutaneous samples indicates the therapeutic potential of this agent for the treatment of infections caused by these fungi. However, the activity of STZ and the clinical value of in vitro data need to be verified in human clinical trials.