How to: EUCAST recommendations on the screening procedure E.Def 10.1 for the detection of azole resistance in Aspergillus fumigatus isolates using four-well azole-containing agar plates

BACKGROUND

The emergence of azole-resistant Aspergillus fumigatus isolates is a matter of significant concern in Europe, with countries reporting resistance rates (which can be as high as 30%) in hospitalized patients. Consequently, the treatment guidelines in The Netherlands, the country with the highest documented prevalence of azole-resistant A. fumigatus, has just been revised to now recommend initial therapy with combination therapy until the susceptibility pattern is known. Therefore, susceptibility testing of clinically relevant isolates has been strongly recommended in the ESCMID-EFISG aspergillosis guidelines. Furthermore, mixed azole-susceptible and azole-resistant (isogenic as well as non-isogenic) infections have been reported to occur, which implies that colonies of clinical cultures may harbour various phenotypes of azole susceptibility.

OBJECTIVES

The EUCAST-AFST (European Committee on Antimicrobial Susceptibility Testing Subcommittee on Antifungal Susceptibility Testing) has released a new screening method document (E.Def 10.1) for the detection of azole-resistant A. fumigatus isolates and updated the QC tables for antifungal susceptibility testing with associated QC endpoints. This review described in detail how to perform the screening test.

SOURCES

This "How to document" is based on the EUCAST azole agar screening method document E.Def 10.1 and the QC tables for antifungal susceptibility testing document, v 2.0 (available at http://www.eucast.org/ast_of_fungi/qcafsttables/) CONTENTS: The method is based on the inoculation of azole-containing and azole-free agars and visual determination of fungal growth after one and two days of incubation. It can easily be implemented in routine laboratories of clinical microbiology and has been validated for simultaneous testing of up to five A. fumigatus colonies using itraconazole and voriconazole (mandatory), and posaconazole (optional).

IMPLICATIONS

This easy-to-use screening procedure for the detection of azole resistance in clinical A. fumigatus isolates will allow rapid testing in the daily routine of the microbiology laboratory and thus facilitate earlier appropriate therapy.

Aspergillus spp. invasive external otitis: favourable outcome with a medical approach

Aspergillus spp. invasive external otitis (IEO) is a rare infection. We performed a seven-year, single-centre retrospective study from 2007 to 2014 including all patients with proven Aspergillus spp. IEO. Twelve patients were identified. All patients had a poorly controlled diabetes mellitus and one underwent solid organ transplant. The most frequently isolated species was Aspergillus flavus (n = 10) and voriconazole was the first-line therapy in all cases, with a median length of treatment of 338.5 days (158-804 days). None of the patients underwent extensive surgery. The clinical outcome was excellent. However, otological sequelae were reported, including hearing impairment (n = 7) and facial palsy (n = 3).

Epidemiology and outcome of systemic infections due to saprochaete capitata: case report and review of the literature

A case of systemic infection due to Saprochaete capitata in a patient with chronic lymphocytic leukemia is described. A review of the literature was conducted to identify all reported cases of this infection described between 1977 and August 2013. One hundred and four cases (included the present one) were identified. The median age of the patients was 56 years and 56% were males. Comorbidities included acute myeloid leukemia (52%), acute lymphoid leukemia (22%), other hematological malignancies (13%) and non-hematological diseases (9%). At the time of the infection, 82% of the patients were neutropenic. In 75% of the cases, the yeast was isolated from blood culture, in 25% from other sterile sites. Empirical treatment was done in 36% of the cases. Fifty-eight percent of the individual cases were treated with a combination or a sequential antifungal therapy. Amphotericin B was the antifungal drug most commonly used, followed by voriconazole and itraconazole. The overall crude mortality was 60%. Saprochaete capitata causes life-threatening infections in neutropenic patients. This comprehensive literature review may help the clinician to optimize the management of this rare infection.

Fluconazole Susceptibility ofCandidaspp. Isolates Collected Over Nine Years in a Teaching Hospital of Ancona, Italy

The in vitro activity of fluconazole was investigated against 476 yeast isolates collected during a 9-year period (1997-2005) from patients hospitalised in a teaching hospital of Ancona. They included 373 isolates of Candida albicans, 53 of Candida glabrata and 50 of Candida parapsilosis. Minimum inhibitory concentrations (MICs) determined in accordance with the Clinical Laboratory Standards Institute methodology showed that 96% of the isolates were susceptible (MIC < or =8.0 microg/ml). The uncommon, resistant isolates (MIC > or =64 microg/ml) were randomly distributed over time. Our data show that resistance to fluconazole in this geographical area is a rare event and suggest that this triazole can still represent first-line therapy in our institution.

SIMIFF study: Italian fungal registry of mold infections in hematological and non-hematological patients

Purpose

We compared the risk factors, the diagnostic tools and the outcome of filamentous fungal infections (FFIs) in hematological patients (HAEs) and non-hematological patients (non-HAEs).

Methods

Prospective surveillance (2009–2011) of proven and probable FFIs was implemented in 23 Italian hospitals.

Results

Out of 232 FFIs, 113 occurred in HAEs and 119 in non-HAEs. The most frequent infection was invasive aspergillosis (76.1 % for HAEs, 56.3 % for non-HAEs), and the localization was principally pulmonary (83.2 % for HAEs, 74.8 % for non-HAEs). Neutropenia was a risk factor for 89.4 % HAEs; the main underlying condition was corticosteroid treatment (52.9 %) for non-HAEs. The distribution of proven and probable FFIs was different in the two groups: proven FFIs occurred more frequently in non-HAEs, whereas probable FFIs were correlated with the HAEs. The sensitivity of the galactomannan assay was higher for HAEs than for non-HAEs (95.3 vs. 48.1 %). The overall mortality rate was 44.2 % among the HAEs and 35.3 % among the non-HAEs. The etiology influenced the patient outcomes: mucormycosis was associated with a high mortality rate (57.1 % for HAEs, 77.8 % for non-HAEs).

Conclusions

The epidemiological and clinical data for FFIs were not identical in the HAEs and non-HAEs. The differences should be considered to improve the management of FFIs according to the patients’ setting.

Osteomyelitis caused by Aspergillus species: a review of 310 reported cases

Aspergillus osteomyelitis is a rare infection. We reviewed 310 individual cases reported in the literature from 1936 to 2013. The median age of patients was 43 years (range, 0-86 years), and 59% were males. Comorbidities associated with this infection included chronic granulomatous disease (19%), haematological malignancies (11%), transplantation (11%), diabetes (6%), pulmonary disease (4%), steroid therapy (4%), and human immunodeficiency virus infection (4%). Sites of infection included the spine (49%), base of the skull, paranasal sinuses and jaw (18%), ribs (9%), long bones (9%), sternum (5%), and chest wall (4%). The most common infecting species were Aspergillus fumigatus (55%), Aspergillus flavus (12%), and Aspergillus nidulans (7%). Sixty-two per cent of the individual cases were treated with a combination of an antifungal regimen and surgery. Amphotericin B was the antifungal drug most commonly used, followed by itraconazole and voriconazole. Several combination or sequential therapies were also used experimentally. The overall crude mortality rate was 25%.

Clinical Efficacy and Tolerability of Caspofungin in a Renal Transplant Patient withAspergillus flavusLung Infection: Case Report

Organ transplant recipients are at increased risk for severe invasive aspergillosis, and amphotericin deoxycholate has been the standard treatment for many years. Currently, however, lipid formulations are preferred due to their few side effects. Also, a number of new antifungal drugs have been developed including new azoles and echinocandins. Caspofungin is the first of the echinocandin derivatives patented to treat patients with invasive aspergillosis who are refractory or intolerant to other therapies. A renal transplant patient on immunosuppressive treatment with chronic hepatitis B virus infection was admitted with fever, hemophthisis and lung consolidation, diagnosed to be probably caused by Aspergillus flavus. The patient developed cholestatic hepatitis most likely related to itraconazole. Clinical failure and in vitro itraconazole resistance of the isolate was also documented while the patient was receiving itraconazole at a reduced dosage. Caspofungin was administered once a day as ambulatory treatment and was well tolerated. Clinical improvement was observed after 6 weeks of treatment and no hepatic toxicity was documented. Caspofungin seems to be a potentially useful antifungal agent in renal transplant patients with invasive aspergillosis. Further evaluation of the efficacy of caspofungin is needed.

Changing characteristics and risk factors of patients with and without incident HCV infection among HIV-infected individuals

BACKGROUND

Chronic hepatitis C virus (HCV) infection has become a leading cause of non-acquired immunodeficiency syndrome (AIDS)-related morbidity and mortality for human immunodeficiency virus (HIV)-infected persons in the highly active antiretroviral therapy (HAART) era. Despite injection drug use (IDU) remaining the main route of HCV infection, recent reports indicate outbreaks of acute HCV infection among HIV-infected men who have sex with men (MSM) and sexually transmitted infections in the absence of IDU.

METHODS

We conducted a retrospective observational study of behavioural and demographic factors of patients with and without incident HCV infection among HIV-infected individuals followed at the AIDS Clinic of the Infectious Disease Department of the University of Ancona from 1989 to 2011.

RESULTS

Overall, 440 patients were considered; a total of 145 patients had initial positive HCV antibody test results (HCV+); a total of 295 patients had initial negative HCV antibody test results (HCV-). In the latter population, 14 seroconverted to HCV antibody (neoHCV), with an overall incidence of 0.59 per 100 person-years. While IDU was the principal risk factor of HCV+, the main route of transmission of incident HCV infection was sexual transmission. The HCV- group was significantly older than the other two groups and showed a significantly lower CD4 count at HIV diagnosis than neoHCV. Being Italian and having a low level of education were significantly more represented in HCV+. Younger age at HIV infection, IDU and additional risk factors other than sexual transmission significantly affected the probability of being HCV+. The cumulative probability of developing HCV infection in the HCV- group was calculated to be 6% at 15 years.

CONCLUSIONS

The epidemiology of the newly acquired HCV in HIV+ persons is changing. Therefore, a frequent and constant counselling about HCV infection is desirable and a periodical screening test is mandatory.

Italian guidelines for diagnosis, prevention, and treatment of invasive fungal infections in solid organ transplant recipients

Use of various induction regimens, of novel immunosuppressive agents, and of newer prophylactic strategies continues to change the pattern of infections among solid organ transplant (SOT) recipients. Although invasive fungal infections (IFIs) occur at a lower incidence than bacterial and viral infections in this population, they remain a major cause of morbidity and mortality worldwide. In March 2008, a panel of Italian experts on fungal infections and organ transplantation convened in Castel Gandolfo (Rome) to develop consensus guidelines for the diagnosis, prevention, and treatment of IFIs among SOT recipients. We discussed the definitions, microbiological and radiological diagnoses, prophylaxis, empirical treatment, and therapy of established disease. Throughout the consensus document, recommendations as clinical guidelines were rated according to the standard scoring system of the Infectious Diseases Society of America and the United Stated Public Health Service.

In vitro activity of the lipopeptide PAL-Lys-Lys-NH2, alone and in combination with antifungal agents, against clinical isolates of Candida spp

Candida albicans is known to be the organism most often associated with serious fungal infection, but other Candida spp. are emerging as clinical pathogens associated with opportunistic infections. Among antimycotic treatments, increasing attention is currently given to anti-infective drugs based upon naturally occurring peptides, such as the short lipopeptide palmitoyl PAL-Lys-Lys-NH2 (PAL). The aim of this study is to evaluate the activity of this peptide compared to the traditional antifungal agents Fluconazole (FLU), amphotericin B (AMB) and caspofungin (CAS) on Candida spp. 24 clinical isolates of Candida spp. were tested against PAL, FLU, AMB and CAS using in vitro susceptibility tests, time killing and checkerboard assay. All of the drugs studied showed good activity against clinical isolates of candida; in particular CAS and AMB which have MICs value lower than PAL and FLU. Moreover we observed synergistic interactions for PAL/FLU (81.25%), PAL/AMB (75%) and particularly for PAL/CAS (87.5). We think that our results are interesting since synergy between PAL and CAS might be useful in clinic trails to treat invasive fungal infections.

In vitro activity of Tachyplesin III alone and in combination with terbinafine against clinical isolates of dermatophytes

Aim of our study was to investigate the in vitro effects of Tachyplesin III (TP), a potent disulfide-linked peptide, in dermatophytes infections, with respect to or in combination with terbinafine (TERB), against 20 clinical isolates of dermatophytes belonging to four species. A broth microdilution method following the CLSI recommendations (M38-A) was used for testing drugs alone and in combination. TERB MICs were significantly lower than those observed for TP (p<0.001). Testing for antifungal agents in combination was performed for TERB with TP for all the 20 isolates. TERB activity in combination with TP showed indifferent activity for 14 of the 20 isolates (70%); synergic activity for 6 of the 20 isolates (30%); no antagonistic activity was observed. Further experiments were conducted with Microsporum canis 133, Trichophyton rubrum 62 and Trichophyton mentagrophytes 91 for fungal biomass. TP and TERB did not show a significant growth reduction compared to the control against T. mentagrophytes and T. rubrum. A significant difference of growth reduction both for TP and TERB compared to controls was observed for M. canis (p<0.01). In conclusion our study demonstrated that Tachyplesin III has potential activity against dermatophytes. In addition, we observed that the in vitro activity of Tachyplesin III can be enhanced upon combination with terbinafine. Synergy could permit lower doses of the individual antifungal agents to be used more effectively and/or safely.

Epidemiology of candidaemia and antifungal susceptibility patterns in an Italian tertiary-care hospital

The epidemiological and antifungal susceptibility data for 94 episodes of candidaemia in an Italian tertiary-care hospital between January 2000 and August 2003 were evaluated by prospective laboratory-based surveillance. The incidence of fungaemia was 0.90 episodes/10 000 patient-days, and the most common species isolated were Candida albicans (40.4%), Candida parapsilosis (22.3%), Candida tropicalis (16.0%) and Candida glabrata (12.8%). Among 24 patients who received antifungal prophylaxis, non-albicans Candida spp. were more prevalent than C. albicans (p 0.012). The 30-day mortality rate was high (38.2%), particularly for haematological (71.4%) and solid-organ transplant patients (50.0%), and in individuals with C. tropicalis and C. glabrata bloodstream infections (60.0% and 50.0%, respectively). In-vitro susceptibility tests demonstrated that 95% of the isolates were susceptible to amphotericin B (MIC < 2 mg/L), 98.1% to posaconazole (MIC < 1 mg/L), 95.8% to flucytosine (MIC < 32 mg/L) and fluconazole (MIC < 64 mg/L), and 94.7% to itraconazole (MIC < 1 mg/L). Posaconazole was active (MIC 0.5 mg/L) against all three isolates of Candida krusei, which had reduced susceptibility to both fluconazole and itraconazole. Overall, non-albicans Candida spp. accounted for 60% of the episodes of candidaemia, which could be related to the use of antifungal prophylaxis. Resistance is still uncommon in Candida spp. recovered from blood cultures. The in-vitro activity of posaconazole is encouraging, and this agent could play an important role in the management of invasive candidiasis, including episodes caused by inherently less susceptible species such as C. krusei.

Comparison of visual 24-hour and spectrophotometric 48-hour MICs to CLSI reference microdilution MICs of fluconazole, itraconazole, posaconazole, and voriconazole for Candida spp.: a collaborative study

A multicenter (six-center) study evaluated the performance (interlaboratory reproducibility, compatibility with reference methods, and categorical agreement) of 24-h visual and 48-h spectrophotometric MICs. MICs of fluconazole, itraconazole, voriconazole, and posaconazole were compared to reference 48-h microdilution broth visual MICs (CLSI [formerly NCCLS] M27-A2 document) for 71 isolates of Candida spp. that included 10 fluconazole-resistant strains. Twenty readings (5%) were reported as showing no growth at 24 h, mostly for Candida dubliniensis and from a single center. The overall interlaboratory agreement of 24-h visual readings and 48-h spectrophotometric MICs, as well their compatibility with reference values, were excellent with the four triazoles for most of the species (93 to 99%, within 3 dilutions). The categorical agreement between the investigational reading conditions and reference values was good with fluconazole and voriconazole (93 to 97%) but lower with itraconazole (86 to 88%), due primarily to minor errors. There were only 0 to 3% very major errors with these three triazoles; the number of substantial errors (more than three dilutions) was also low (<2%) with posaconazole. These data suggest that the performance of both investigational MIC readings gives results similar to those of reference MICs. Since spectrophotometric MICs are more objective and the 24-h time period would shorten the MIC determination of azoles, the description of either of these two reading conditions in the M27-A2 document should be considered by the CLSI subcommittee in addition to or instead of the longer, less practical, and more subjective 48-h visual MIC reading.

International and multicenter comparison of EUCAST and CLSI M27-A2 broth microdilution methods for testing susceptibilities of Candida spp. to fluconazole, itraconazole, posaconazole, and voriconazole

The aim of this study was to compare MICs of fluconazole, itraconazole, posaconazole, and voriconazole obtained by the European Committee on Antibiotic Susceptibility Testing (EUCAST) and CLSI (formerly NCCLS) methods in each of six centers for 15 Candida albicans (5 fluconazole-resistant and 4 susceptible-dose-dependent [S-DD] isolates), 10 C. dubliniensis, 7 C. glabrata (2 fluconazole-resistant isolates), 5 C. guilliermondii (2 fluconazole-resistant isolates), 10 C. krusei, 9 C. lusitaniae, 10 C. parapsilosis, and 5 C. tropicalis (1 fluconazole-resistant isolate) isolates. CLSI MICs were obtained visually at 24 and 48 h and spectrophotometric EUCAST MICs at 24 h. The agreement (within a 3-dilution range) between the methods was species, drug, and incubation time dependent and due to lower EUCAST than CLSI MICs: overall, 94 to 95% with fluconazole and voriconazole and 90 to 91% with posaconazole and itraconazole when EUCAST MICs were compared against 24-h CLSI results. The agreement was lower (85 to 94%) against 48-h CLSI endpoints. The overall interlaboratory reproducibility by each method was > or =92%. When the comparison was based on CLSI breakpoint categorization, the agreement was 68 to 76% for three of the four species that included fluconazole-resistant and S-DD isolates; 9% very major discrepancies (< or =8 microg/ml versus > or =64 microg/ml) were observed among fluconazole-resistant isolates and 50% with voriconazole (< or =1 microg/ml versus > or =4 microg/ml). Similar results were observed with itraconazole for seven of the eight species evaluated (28 to 77% categorical agreement). Posaconazole EUCAST MICs were also substantially lower than CLSI MIC modes (0.008 to 1 microg/ml versus 1 to > or =8 microg/ml) for some of these isolates. Therefore, the CLSI breakpoints should not be used to interpret EUCAST MIC data.

Comparative analysis of pathogenicity of Cryptococcus neoformans serotypes A, D and AD in murine cryptococcosis

OBJECTIVES

To characterize the pathogenicity of 15 strains of Cryptococcus neoformans belonging to several serotype/mating type allele patterns (Dalpha, Da, A(alpha), A(a), A(alpha)/D(a) and D(alpha)/A(a)) in experimental models of murine cryptococcosis.

METHODS

CD1-infected mice were examined for survival and fungal loads in either brain or lung during the course of infection.

RESULTS

All strains, with the exception of one Da strain, produced melanin in vitro. Similarly, all strains were encapsulated and produced phospholipase. When CD1 mice were challenged intravenously (i.v.) with 5x10(5)CFU/mouse and observed for 60 days post-infection, a significant variation of mortality rate was observed among mice infected with different strains. A(alpha) and A(alpha)/D(a) strains all produced 100% mortality within the study period with mean survivals significantly shorter than those of mice infected with strains belonging to any other allele type (P<0.0001). A wide range of pathogenicity was shown by haploid and diploid strains presenting D(alpha) allele. This finding was confirmed by an intranasal model of challenge. To investigate the progression of infection, the mice were challenged i.v. with 5x10(4)CFU/mouse and tissue burden experiments (brain and lung) were performed on days 6 and 12 post-infection. Only the mice infected with A(alpha) and A(alpha)/D(a) strains showed a >1 log(10) increase of CFU/g in both tissues throughout the study period.

CONCLUSIONS

Our results suggest that the presence of the A(alpha) mating type allele in either haploid or diploid strains is correlated with virulence, while the presence of the A(a) or D(a) allele in haploid strains is associated with moderate or no virulence. Finally, either haploid or diploid strains presenting D(alpha) allele vary in virulence.

Epidemiology of onychomycosis and paronychia in the area of ANCONA (ITALY) over a period of 5 years

We retrospectively evaluated the epidemiology of onychomycosis and/or paronychia in 172 patients attending the Clinic of Dermatology and Venereology over a 5 year period. Although yeast isolates, belonging to the Candida species, represented the most frequent etiologic agents of these infections, an increasing prevalence of fungal infections due to emerging fungal pathogens (EFP) was noted throughout this time period. In particular, EFP as causative agents of these infections increased from 0 to 28.4% from 1998 to 2002.

Genotypic variation and antifungal susceptibilities of Candida pelliculosa clinical isolates

At the Istituto Ricovero Cura Carattere Scientifico, Ospedale Maggiore di Milano, Italy, Candida pelliculosa accounted for 3.3 and 4.4 % of all Candida species other than Candida albicans collected during 1996 and 1998, respectively. Genetic variability was investigated by electrophoretic karyotyping and inter-repeat PCR, and the susceptibility to five antifungal agents of 46 strains isolated from 37 patients during these 2 years was determined. Combination of the two typing methods yielded 14 different DNA types. Although the majority of DNA types were randomly distributed among different units, one DNA type was significantly more common in patients hospitalized in a given unit compared with those from other wards (P = 0.034), whereas another DNA type was more frequently isolated in patients hospitalized during 1996 than in those hospitalized during 1998 (P = 0.002). Fluconazole, itraconazole and posaconazole MIC90 values were 16, 1 and 4 μg ml−1, respectively. All isolates but three were susceptible in vitro to flucytosine. All isolates were susceptible in vitro to amphotericin B. These data suggest that there are possible relationships among strains of C. pelliculosa, wards and time of isolation. Amphotericin B seems to be the optimal drug therapy in infections due to this yeast species.

Outbreak of fungemia due to Candida parapsilosis in a pediatric oncology unit

We report an outbreak of infection due to genotypically identical Candida parapsilosis isolates among patients hospitalized in a pediatric oncology unit. Control cultures showed genetic relatedness between strains isolated from the patients and those isolated from the hands of a health care worker. Our data underline the importance of an effective surveillance program for preventing nosocomial fungal infections.

Multicenter evaluation of the reproducibility of the proposed antifungal susceptibility testing method for fermentative yeasts of the Antifungal Susceptibility Testing Subcommittee of the European Committee on Antimicrobial Susceptibility Testing (AFST-EUCAST)

OBJECTIVE

To evaluate the intra- and inter-laboratory reproducibility of a new standard for susceptibility testing of fermentative yeasts. This standard is based on the M27-A procedure of the National Committee for Clinical Laboratory Standards (NCCLS), but incorporates several modifications, including spectrophotometric growth-dependent endpoint reading.

METHODS

Nine laboratories participated in the study. Common material lots were used to test six Candida species (one each of C. albicans, C. tropicalis, C. parapsilosis, C. glabrata, C. krusei, and C. lusitaniae), and two quality control strains (C. krusei ATCC6258 and C. parapsilosis ATCC22019). Triplicate testing on three separate days was performed in microtiter format with RPMI-2% glucose, pH 7.0. Flucytosine, fluconazole and itraconazole were tested. In total, 3888 MIC values were included in the analyses. Reproducibility was calculated by means of agreement (percentage of MICs within one two-fold dilution of the mode) and intraclass correlation coefficient (ICC, maximum value of 1).

RESULTS

The average intra-laboratory agreements were 99% and 96% after 24 h and 48 h of incubation, respectively, with ICCs of 0.98 and 0.97 (P < 0.05). Two strains exhibiting a trailing effect showed intra-laboratory agreement of 92% and ICCs of < 0.91 at 48 h. The inter-laboratory agreement was 94% and 88% after 24 h and 48 h, respectively, with ICCs of 0.93 and 0.91 (P < 0.05). Lower values of agreement and ICCs were obtained for strains exhibiting trailing after 48 h of incubation. Itraconazole yielded the lowest values of reproducibility.

CONCLUSION

The new procedure of EUCAST for antifungal susceptibility testing is a reproducible method within and between laboratories and offers several advantages over the NCCLS approved method.

Genotyping and antifungal susceptibility of human subgingival Candida albicans isolates

Subgingival colonization by Candida albicans has been described in human immunodeficiency virus (HIV)-infected individuals, but subgingival isolates have scarcely been characterized, particularly with respect to genotype and antifungal susceptibility. A series of 29 subgingival strains of C. albicans isolated from nine HIV-infected individuals was typed by electrophoretic karyotyping and tested for susceptibility to fluconazole, itraconazole, the new investigational triazole posaconazole and amphotericin B. DNA typing showed genetic heterogeneity within subgingival isolates, as almost every individual harbored his/her own specific isolate. Genetic identity was usually demonstrated within oral and subgingival isolates simultaneously collected from the same individual, but a number of DNA types were found to be unique to subgingival strains. These findings suggest that colonization is not just the result of Candida spreading from oral surfaces, and that subgingivally adapted strains could be involved. All isolates were susceptible to all the triazole drugs tested and amphotericin B. Additional studies on subgingival Candida colonization and further characterization of subgingival isolates are now required to clarify the role of Candida as opportunistic periodontal pathogen.

Activity of the new antifungal triazole, posaconazole, against Cryptococcus neoformans

The new antifungal derivative posaconazole was tested against three clinical isolates of Cryptococcus neoformans var. neoformans using a broth microdilution procedure performed according to the guidelines established by the NCCLS. Posaconazole MICs were 0.125, 0.25 and 1.0 mg/L for isolates 491, 2337 and 486, respectively. To investigate the in vivo activity of this new compound, we established an experimental model of systemic cryptococcosis in CD1 mice by iv injection of cells of each strain of C. neoformans. Low (3 mg/kg/day) and high (10 mg/kg/day) doses of posaconazole were compared with amphotericin B given at 0.3 mg/kg/day for 10 consecutive days. Survival studies showed that all treatment regimens were effective in prolonging the survival of mice infected with C. neoformans 486 (P < 0.001). Only posaconazole at 10 mg/kg and amphotericin B were effective in prolonging the survival in mice infected with C. neoformans 2337 (P from <0.01 to <0.001), while neither agent was effective in mice infected with C. neoformans 491. Tissue burden experiments performed 24 h after the end of therapy revealed that posaconazole at 10 mg/kg was effective at reducing the fungal burden in both lung and brain tissues of all three strains of C. neoformans. In particular, for C. neoformans 491 and 2337 posaconazole was superior to amphotericin B at reducing the fungal burden in the brain (P < 0.05). The efficacy of posaconazole was also confirmed by determining the capsular antigen serum levels of treated mice versus untreated mice. Our study underlines the excellent activity of posaconazole against this pathogenic yeast.

In vitro activity of posaconazole against clinical isolates of dermatophytes

A broth macrodilution method following the recommendations established by the National Committee for Clinical Laboratory Standards was used to compare the in vitro activity of posaconazole (PCZ) with that of itraconazole (ITC) against 30 clinical isolates of dermatophytes belonging to six different species. In terms of MICs, PCZ showed an activity equal to that of ITC. MICs of PCZ at which 50% (MIC(50)) and 90% (MIC(90)) of the isolates were inhibited were 0.5 and > 4.0 microg/ml, respectively. The MIC(50) and MIC(90) of ITC were 1.0 and > 4.0 microg/ml, respectively. However, PCZ showed a more potent fungicidal activity than that of ITC against isolates belonging to the genus Microsporum (P = 0.03). PCZ merits further investigation as a potentially useful agent for treatment of dermatophytosis.

Electrophoretic karyotyping and antifungal susceptibility patterns of Candida parapsilosis clinical isolates causing deep and superficial fungal infections

Forty-six isolates of Candida parapsilosis, each from a single patient, were collected from July 1993 through March 1999 at the University of Ancona Hospitals and Clinics. Twenty-eight strains were isolated from superficial lesioned sites, including skin, nails and other sources while 18 strains were isolated from blood. The isolates were typed by electrophoretic karyotyping (EK) and tested for their susceptibility to fluconazole (FLC), itraconazole (ITC), flucytosine (5-FC), and amphotericin B (AMB). Our data confirmed that EK is a useful technique for DNA typing of isolates of Candida parapsilosis and showed that the source of isolation is not associated with a given DNA type. Although strains belonging to this species of Candida are susceptible to the most common antifungals, including the triazoles, the degree of ITC susceptibility was dose dependent (MIC ranging from 0.25-0.5 microgram/ml) for 98% of the isolates.

Interactions of posaconazole and flucytosine against Cryptococcus neoformans

A checkerboard methodology, based on standardized methods proposed by the National Committee for Clinical Laboratory Standards for broth microdilution antifungal susceptibility testing, was applied to study the in vitro interactions of flucytosine (FC) and posaconazole (SCH 56592) (FC-SCH) against 15 isolates of Cryptococcus neoformans. Synergy, defined as a fractional inhibitory concentration (FIC) index of <0.50, was observed for 33% of the isolates tested. When synergy was not achieved, there was still a decrease in the MIC of one or both drugs when they were used in combination. Antagonism, defined as a FIC of >4.0, was not observed. The in vitro efficacy of combined therapy was confirmed by quantitative determination of the CFU of C. neoformans 486, an isolate against which the FC-SCH association yielded a synergistic interaction. To investigate the potential beneficial effects of this combination therapy in vivo, we established two experimental murine models of cryptococcosis by intracranial or intravenous injection of cells of C. neoformans 486. At 1 day postinfection, the mice were randomized into different treatment groups. One group each received each drug alone, and one group received the drugs in combination. While combination therapy was not found to be significantly more effective than each single drug in terms of survival, tissue burden experiments confirmed the potentiation of antifungal activity with the combination. Our study demonstrates that SCH and FC combined are significantly more active than either drug alone against C. neoformans in vitro as well in vivo. These findings suggest that this therapeutic approach could be useful in the treatment of cryptococcal infections.

Activity of buforin II alone and in combination with azithromycin and minocycline against Cryptosporidium parvum in cell culture

The in vitro anti-cryptosporidial activity of buforin II alone and in combination with azithromycin and minocycline was investigated. Buforin II showed moderate activity, which increased with increasing concentration to 55.7% suppression of growth at 20 microM. Moreover, its activity was enhanced when it was combined with either azithromycin or minocycline with >90% parasite reduction at the highest concentration tested. Buforin II may be active in inhibiting Cryptosporidium parvum growth in vitro upon combination with either azithromycin or minocycline.

Short-term exposure to membrane-active antibiotics inhibits Cryptosporidium parvum infection in cell culture

A cell culture system and double fluorogenic staining were used to study the susceptibility of Cryptosporidium parvum to membrane-active antibiotics. Buforin II and magainin II exerted a cytotoxic effect on sporozoites but did not consistently affect oocyst viability. Lasalocid and nigericin demonstrated less activity against sporozoites but reduced the infectivity of oocysts.

Comparative activities of polycationic peptides and clinically used antimicrobial agents against multidrug-resistant nosocomial isolates of Acinetobacter baumannii

The in vitro activity of buforin II, cecropin P1, indolicidin, magainin II and ranalexin, alone and in combination with eight clinically used antimicrobial agents was investigated against 12 multidrug-resistant strains of Acinetobacter baumannii isolated from immunocompromised patients. Antimicrobial activities were measured by MIC, MBC and viable count. The peptides had a varied range of inhibitory values: overall, the organisms were more susceptible to buforin II (MIC range 0.25-16 mg/L), cecropin P1 (0.50-32 mg/L) and magainin II (0.50-16 mg/L). Synergy occurred when magainin II was combined with beta-lactam antibiotics.

In-vitro activity and killing effect of polycationic peptides on methicillin-resistant Staphylococcus aureus and interactions with clinically used antibiotics

The in-vitro activity of nisin, a 34-residue peptide produced by several Lactococcus lactis strains, and ranalexin, a 20-residue peptide isolated from the skin of the bullfrog Rana catesbeiana, alone and in combination with amoxycillin, amoxycillin-clavulanate, imipenem, clarithromycin, ciprofloxacin, rifampin and vancomycin was investigated against 40 nosocomial isolates of methicillin-resistant Staphylococcus aureus (MRSA). All isolates were inhibited at concentrations of 1 to 32 microg/ml. Synergy was observed when the peptides were combined with other agents, with the exception of the beta-lactams. Finally, the consecutive exposures to each peptide did not result in selection of stable mutants with decreased susceptibility. Our finding show that nisin and ranalexin are active against MRSA, and that their activity is enhanced when they are combined with several antimicrobial agents.

Inhibition of growth of Pneumocystis carinii by lactoferrins alone and in combination with pyrimethamine, clarithromycin and minocycline

The in vitro activity of lactoferrins alone and in combination with clarithromycin, minocycline and pyrimethamine was investigated against three clinical isolates of Pneumocystis carinii. Susceptibility was tested by inoculating isolates on to cell monolayers and determining the parasite count after 72 h incubation at 37 degrees C. The culture medium was supplemented with serial dilutions of each agent. At 20 mg/L, bovine lactoferrin, the most active agent, suppressed the growth of cystic and trophic forms by >60%. Human lactoferrin, at the same concentration, suppressed the growth of cystic and trophic forms by >50%. Lactoferrins at 20 mg/L combined with clarithromycin 4 mg/L had high anti-P. carinii activity, with a >90% decrease in cystic and trophic form counts. Our study suggests that lactoferrins may inhibit P. carinii growth in vitro and act synergically with other clinically used compounds. These findings lend experimental support to the use of iron-chelating agents in the therapy of pneumocystis infections.

Interactions between triazoles and amphotericin B against Cryptococcus neoformans

The interaction of amphotericin B (AmB) and azole antifungal agents in the treatment of fungal infections is still a controversial issue. A checkerboard titration broth microdilution-based method that adhered to the recommendations of the National Committee for Clinical Laboratory Standards was applied to study the in vitro interactions of AmB with fluconazole (FLC), itraconazole (ITC), and the new investigational triazole SCH 56592 (SCH) against 15 clinical isolates of Cryptococcus neoformans. Synergy, defined as a fractional inhibitory concentration (FIC) index of < or =0.50, was observed for 7% of the isolates in studies of the interactions of both FLC-AmB and ITC-AmB and for 33% of the isolates in studies of the SCH-AmB interactions; additivism (FICs, >0.50 to 1.0) was observed for 67, 73, and 53% of the isolates in studies of the FLC-AmB, ITC-AmB, and SCH-AmB interactions, respectively; indifference (FICs, >1.0 to < or =2.0) was observed for 26, 20, and 14% of the isolates in studies of the FLC-AmB, ITC-AmB, and SCH-AmB interactions, respectively. Antagonism (FIC >2.0) was not observed. When synergy was not achieved, there was still a decrease, although not as dramatic, in the MIC of one or both drugs when they were used in combination. To investigate the effects of FLC-AmB combination therapy in vivo, we established an experimental model of systemic cryptococcosis in BALB/c mice by intravenous injection of cells of C. neoformans 2337, a clinical isolate belonging to serotype D against which the combination of FLC and AmB yielded an additive interaction in vitro. Both survival and tissue burden studies showed that combination therapy was more effective than FLC alone and that combination therapy was at least as effective as AmB given as a single drug. On the other hand, when cells of C. neoformans 2337 were grown in FLC-containing medium, a pronounced increase in resistance to subsequent exposures to AmB was observed. In particular, killing experiments conducted with nonreplicating cells showed that preexposure to FLC abolished the fungicidal activity of the polyene. However, this apparent antagonism was not observed in vivo. Rather, when the two drugs were used sequentially for the treatment of systemic murine cryptococcosis, a reciprocal potentiation was often observed. Our study shows that (i) the combination of triazoles and AmB is significantly more active than either drug alone against C. neoformans in vitro and (ii) the concomitant or sequential use of FLC and AmB for the treatment of systemic murine cryptococcosis results in a positive interaction.

In vivo antigen loading and activation of dendritic cells via a liposomal peptide vaccine mediates protective antiviral and anti-tumour immunity

Initiation of antiviral and anti-tumour T cell responses is probably achieved mainly by dendritic cells (DC) transporting antigen from the periphery into organised lymphoid tissues. To develop T cell vaccines it is, therefore, important to understand the accessibility of the antigen to DC in vivo and whether DC are activated by vaccination. Here we have evaluated the immunogenicity of a liposomal vaccine formulation with antigenic peptides derived from the glycoprotein of the lymphocytic choriomeningitis virus. Liposome-encapsulated peptides were highly immunogenic when administered intradermally and elicited protective antiviral immunity. After intradermal injection, liposomes formed antigen depots which facilitated long-lasting in vivo antigen loading of dendritic cells almost exclusively in the local draining lymph nodes. The immunogenicity of the liposomal peptide vaccine was further enhanced by incorporation of immunostimulatory oligonucleotides leading to activation of DC. This optimised liposomal peptide vaccine elicited also anti-tumour immunity and induced CTL responses comparable to adoptively transferred, peptide-presenting DC. Thus, our data show that liposomal formulations of peptide vaccines are highly effective at direct in vivo antigen loading and activation of DC leading to protective antiviral and anti-tumour immune responses.

Clinical manifestations and molecular epidemiology of late recurrent candidemia, and implications for management

The aim of this study was to define the epidemiology and clinical manifestations of late recurrent candidemia. For this purpose, late recurrent candidemia was defined as an episode of candidemia occurring at least 1 month after the apparent complete resolution of an infectious episode caused by the same Candida sp. A total of five patients with recurrent candidemia were investigated. For all patients, isolates from the initial and recurrent episodes of candidemia were available for in vitro susceptibility testing and genetic characterization by DNA-based techniques. The results revealed the following salient features: prolonged duration between the initial and recurrent episodes (range, 1-8 months); recurrence of candidemia despite anti-fungal therapy; importance of retained intravascular catheters, neutropenia, and corticosteroids as factors predisposing to recurrence; high morbidity and mortality; no emergence of antifungal drug resistance between the initial and recurrent episodes; and relapse of infection due to the original infecting strain, rather than reinfection with a new strain. These findings raise several issues about the management and follow-up of patients with candidemia, which require assessment in future studies.

Treatment of murine cryptococcal meningitis with UR-9751 and UR-9746

In these studies, we compare the efficacy of two new azole antifungals with fluconazole in a murine model of cryptococcal meningitis. Mice were infected intracranially. Beginning one day later, groups of 7-10 mice were treated through to day 10 orally with UR-9751 or UR-9746 at 0.1, 0.25, 0.5, 1 or 10 mg kg(-1) day(-1) or fluconazole at 10 mg kg(-1) day(-1). At 10 mg kg(-1) day(-1), all three drugs prolonged survival over controls, but at 1 mg kg(-1) day(-1) only UR-9746 prolonged survival. Tissue counts were more varied on mice sacrificed 8 days after infection. In general, both UR drugs were equal or more potent than fluconazole, and UR-9751 was more effective than UR-9746.

Experimental induction of fluconazole resistance in Candida tropicalis ATCC 750

Candida tropicalis is less commonly isolated from clinical specimens than Candida albicans. Unlike C. albicans, which can be occasionally found as a commensal, C. tropicalis is almost always associated with the development of fungal infections. In addition, C. tropicalis has been reported to be resistant to fluconazole (FLC). To analyze the development of FLC resistance in C. tropicalis, an FLC-susceptible strain (ATCC 750) (MIC = 1.0 microg/ml) was cultured in liquid medium containing increasing FLC concentrations from 8.0 to 128 microg/ml. The strain developed variable degrees of FLC resistance which paralleled the concentrations of FLC used in the medium. The highest MICs of FLC were 16, 256, and 512 microg/ml for strains grown in medium with 8.0, 32, and 128 microg of FLC per ml, respectively. Development of resistance was rapid and could be observed already after a single subculture in azole-containing medium. The resistant strains were cross-resistant to itraconazole (MIC > 1.0 microg/ml) and terbinafine (MIC > 512 microg/ml) but not to amphotericin B. Isolates grown in FLC at concentrations of 8.0 and 32 microg/ml reverted to low MICs (1.0 microg/ml) after 12 and 11 passages in FLC-free medium, respectively. The MIC for one isolate grown in FLC (128 microg/ml) (128 R) reverted to 16 microg/ml but remained stable over 60 passages in FLC-free medium. Azole-resistant isolates revealed upregulation of two different multidrug efflux transporter genes: the major facilitators gene MDR1 and the ATP-binding cassette transporter CDR1. The development of FLC resistance in vitro correlated well with the results obtained in an experimental model of disseminated candidiasis. While FLC given at 10 mg/kg of body weight/day was effective in reducing the fungal burden of mice infected with the parent strain, the same dosing regimen was ineffective in mice infected with strain 128 R. Finally, the acquisition of in vitro FLC resistance in strain 128 R was related to a loss of virulence. The results of our study elucidate important characteristics and potential mechanisms of FLC resistance in C. tropicalis.

In vitro susceptibility tests for cationic peptides: comparison of broth microdilution methods for bacteria that grow aerobically

The in vitro susceptibilities of 90 clinical isolates of gram-positive and gram-negative aerobic bacteria to six cationic peptides, buforin II, cecropin P1, indolicidin, magainin II, nisin, and ranalexin, were evaluated by two broth microdilution methods. The first method was performed according to the procedures outlined by the National Committee for Clinical Laboratory Standards for bacteria that grow aerobically, while the second was performed according to the procedures recently proposed by the R. E. W. Hancock laboratory for testing antimicrobial peptides. Overall, the first method produced MICs two- and fourfold higher than the second method.

In vitro activities of membrane-active peptides alone and in combination with clinically used antimicrobial agents against Stenotrophomonas maltophilia

The in vitro activities of buforin II, cecropin P1, and magainin II, alone and in combination with six clinically used antimicrobial agents, against 12 clinical isolates of Stenotrophomonas maltophilia were investigated. Antimicrobial activities were measured by MIC and time-kill studies. The isolates were susceptible to the peptides at concentrations in the range of 0.50 to 16 microg/ml. Synergy was observed when the peptides were combined with polymyxin E, meropenem, ceftazidime, piperacillin, and clarithromycin.