Fungemia in children infected with the human immunodeficiency virus: new epidemiologic patterns, emerging pathogens, and improved outcome with antifungal therapy

QSAR classification model for diverse series of antifungal agents based on binary coyote optimization algorithm

One of the recently developed metaheuristic algorithms, the coyote optimization algorithm (COA), has shown to perform better in a number of difficult optimization tasks. The binary form, BCOA, is used in this study as a solution to the descriptor selection issue in classifying diverse antifungal series. Z-shape transfer functions (ZTF) are evaluated to verify their efficiency in improving BCOA performance in QSAR classification based on classification accuracy (CA), the geometric mean of sensitivity and specificity (G-mean), and the area under the curve (AUC). The Kruskal-Wallis test is also applied to show the statistical differences between the functions. The efficacy of the best suggested transfer function, ZTF4, is further assessed by comparing it to the most recent binary algorithms. The results prove that ZTF, especially ZTF4, significantly improves the performance of the original BCOA. The ZTF4 function yields the best CA and G-mean of 99.03% and 0.992%, respectively. It shows the fastest convergence behaviour compared to other binary algorithms. It takes the fewest iterations to reach high classification performance and selects the fewest descriptors. In conclusion, the obtained results indicate the ability of the ZTF4-based BCOA to find the smallest subset of descriptors while maintaining the best classification accuracy performance.

Invasive Fungal Infections in Under-Five Diarrheal Children: Experience from an Urban Diarrheal Disease Hospital

Invasive fungal infections (IFIs) are opportunistic, especially in immunocompromised and hospitalized patients. Children with IFIs are more vulnerable to a fatal outcome. For early diagnosis and treatment, knowledge of the spectrum and frequency of IFIs among children is prerequisite. In this prospective observational study, we enrolled 168 children of 2–59 months old of either sex from March 2018 to December 2019 admitted to the Dhaka hospital, icddr,b. Study participants with suspected IFIs were with or without severe acute malnutrition (SAM) along with sepsis/pneumonia and fulfilled any of the following criteria: (i) failure to respond to injectable antibiotics, (ii) development of a late-onset hospital-acquired infection, (iii) needed ICU care for >7 days, (iv) took steroids/antibiotics for >2 weeks before hospitalization, and (v) developed thrush after taking injectable antibiotics. The comparison group included non-SAM (weight-for-length Z score ≥ −2) children with diarrhea and fever <3 days in the absence of co-morbidity. We performed real-time PCR, ELISA, and blood culture for the detection of fungal pathogen. Study group children with SAM, positive ELISA and PCR considered to have a IFIs. In the study group, 15/138 (10.87%) children had IFIs. Among IFIs, invasive candidiasis, aspergillosis, histoplasmosis detected in 6 (4.53%), 11 (7.97%), and 1 (0.72%) children, respectively, and (3/15 [2.17%]) children had both candidiasis and aspergillosis. Children with IFIs more often encountered septic shock (26.7% vs. 4.9%; p = 0.013) and had a higher death rate (46.7% vs. 8.9%; p < 0.001) than those without IFIs. IFIs were independently associated with female sex (OR = 3.48; 95% CI = 1.05, 11.55; p = 0.042) after adjusting for potential confounders. Our findings thus implicate that, malnourished children with septic shock require targeted screening for the early diagnosis and prompt management of IFIs that may help to reduce IFIs related deaths.

Quantitative structure-activity relationship model for classifying the diverse series of antifungal agents using ratio weighted penalized logistic regression

One of the most challenging issues when facing a Quantitative structure-activity relationship (QSAR) classification model is to deal with the descriptor selection. Penalized methods have been adapted and have gained popularity as a key for simultaneously performing descriptor selection and QSAR classification model estimation. However, penalized methods have drawbacks such as having biases and inconsistencies that make they lack the oracle properties. This paper proposes an adaptive penalized logistic regression (APLR) to overcome these drawbacks. This is done by employing a ratio (BWR) of the descriptors between-groups sum of squares (BSS) to the within-groups sum of squares (WSS) for each descriptor as a weight inside the L₁-norm. The proposed method was applied to one dataset that consists of a diverse series of antimicrobial agents with their respective bioactivities against Candida albicans. By experimental study, it has been shown that the proposed method (APLR) was more efficient in the selection of descriptors and classification accuracy than the other competitive methods that could be used in developing QSAR classification models. Another dataset was also successfully experienced. Therefore, it can be concluded that the APLR method had significant impact on QSAR analysis and studies.

QSAR classification model for diverse series of antifungal agents based on improved binary differential search algorithm

An improved binary differential search (improved BDS) algorithm is proposed for QSAR classification of diverse series of antimicrobial compounds against Candida albicans inhibitors. The transfer functions is the most important component of the BDS algorithm, and converts continuous values of the donor into discrete values. In this paper, the eight types of transfer functions are investigated to verify their efficiency in improving BDS algorithm performance in QSAR classification. The performance was evaluated using three metrics: classification accuracy (CA), geometric mean of sensitivity and specificity (G-mean), and area under the curve. The Kruskal-Wallis test was also applied to show the statistical differences between the functions. Two functions, S1 and V4, show the best classification achievement, with a slightly better performance of V4 than S1. The V4 function takes the lowest iterations and selects the fewest descriptors. In addition, the V4 function yields the best CA and G-mean of 98.07% and 0.977%, respectively. The results prove that the V4 transfer function significantly improves the performance of the original BDS.

Candida Soluble Cell Wall β-D-Glucan Induces Lung Inflammation in Mice

Bioactivity of cell wall component(s) of fungi has not been fully elucidated, especially in vivo. We isolated Candida soluble beta-D-glucan (CSBG) from Candida albicans (C. albicans). We investigated the effects of airway exposure to CSBG on the immune systems in the airways in mice. CSBG exposure induced neutrophilic and eosinophilic inflammation in the lung, which was concomitant with the increased local expression of proinflammatory cytokines including tumor necrosis factor - α, interleukin (IL)-1 β, IL-6, macrophage inflammatory protein -1 α, macrophage chemoattractant protein -1, RANTES (regulated on activation and normal T cells expressed and secreted), and eotaxin. The lung inflammation with enhanced expression of proinflammatory proteins caused by CSBG was directly related to its structure, since structurally degraded products of CSBG by formic acid induced negligible responses in the lung. CSBG enhanced nuclear localization of phosphorylated signal transducer and activator of transcription (STAT)-6 in the lung. These results suggest that airway exposure to CSBG induces lung inflammation, at least partly, via the enhanced expression of proinflammatory cytokines and the activation of STAT-6 pathway, and can be a proper murine model for fungal lung inflammation.

Unilateral renal phaeohyphomycosis due to Bipolaris spicifera in an immunocompetent child - rare case presentation and review of literature

Phaeohyphomycosis refers to infections caused by phaeoid fungi that can have an aggressive course in normal hosts. We report a case of left-sided renal phaeohyphomycosis due to Bipolaris spicifera in a 7-year-old immunocompetent male child. He presented with fever, dysuria, nausea, vomiting and flank pain. Examination revealed tenderness at the left costovertebral angle. Histological examination and culture of biopsy from left kidney and blood yielded the fungal pathogen Bipolaris spicifera. His past history revealed that he was diagnosed perinatally with bilateral hydronephrosis due to bilateral pelvic ureteric junction obstruction. He underwent an open dismembered pyeloplasty on the left side followed by the right side pyeloplasty at the age of 6 months and 1.5 years respectively. He was on a regular follow-up for 5 years and had been doing well. Now he was diagnosed as a case of unilateral renal phaeohyphomycosis. The patient was managed successfully with antifungal drugs amphotericin B and itraconazole. A review of previously reported bipolaris cases with their clinical manifestations, treatment and outcome is presented. Renal phaeohyphomycosis remains an unusual disease. Aggressive diagnostic approaches and careful management helped in survival of the patient.

What do we know about Candida guilliermondii? A voyage throughout past and current literature about this emerging yeast

Candida guilliermondii is an uncommon isolate throughout most of the world, the behaviour of which as an environmental fungus, a human saprophyte and an agent of serious infections has been emphasised over the years. Notably, illnesses caused by this pathogen mostly involve compromised cancer hosts and commonly lead patients to unfavourable outcomes. It is of concern that the yeast may acquire or inherently express reduced in vitro sensitivity to all antifungal classes, although widespread resistance has not yet been described, and poor correlation exists between MICs and clinical outcome. However, the organism appears as constitutively less susceptible to polyenes and echinocandins than other yeast-like fungi, so that the emergence of such pathogen in the clinical settings is of concern and may appear as a new challenge in the context of mycoses and antifungal therapy.

Candida bloodstream infections in hemodialysis recipients

Candidemia is a major cause of morbidity and mortality in patients undergoing hemodialysis but it has not been well defined in this patient population. We performed a retrospective case-control study to characterize the epidemiology, microbiology, and outcomes of hemodialysis-associated candidemia. All cases of candidemia at our institution were evaluated from 1 January 2000 until 1 September 2004. For each case, two non-candidemic dialysis patients served as controls. Among 350 cases of candidemia, 78 (22%) occurred in adult hemodialysis patients. Cases and controls were similar with respect to age, corticosteroid, antibiotics use, prevalence of diabetes mellitus, liver cirrhosis, surgical procedures, and cancer. Multivariate analysis found total parenteral nutrition (TPN) (19.5% vs. 1.3%; P<0.0001) and dialysis through a vascular catheter (74% vs. 46.8%; P=0.0001) to be independently associated with candidemia. Non-C.albicans Candida spp. particularly C. glabrata and C. krusei were more common in hemodialysis recipients than in candidemic patients not receiving hemodialysis (31% vs. 17% p = 0.009). In-hospital mortality was significantly elevated for candidemic vs. non-candidemic hemodialysis recipients (51.9% vs. 7.8%; P<0.0001). Candidemia in hemodialysis recipients is frequently caused by non-C. albicansCandida species, is associated with TPN and dialysis via a vascular catheter (vs. shunt or fistula) and carries a high mortality rate.

Soluble cell wall beta-glucan of Candida induces/enhances apoptosis and oxidative stress in murine lung

The bioactivity of cell wall component(s) of fungi has not been fully investigated, especially in vivo. We have successfully extracted a soluble cell wall beta-glucan from C. albicans (CSBG), and shown that pulmonary exposure to CSBG induces lung inflammation in mice. CSBG-induced lung inflammation was concomitant with the nuclear translocation of signal transducer and activator of transcription (STAT)6 and enhanced lung expression of various cytokines and chemokines. However, the effects of CSBG on the murine respiratory system and their mechanisms have not been fully investigated. In this study, we further explored the effects of pulmonary exposure to CSBG on lung pathophysiology in terms of the induction of apoptosis and enhancement of oxidative stress. ICR mice were intratracheally instilled with vehicle, CSBG, or structurally degraded products of CSBG by formic acid (DEG-CSBG), and 24 h later, the lungs were isolated and evaluated for apoptosis by the TUNEL assay and oxidative stress by immunohistochemistry of 8-hydroxy-2'-deoxyguanosine (8-OHdG), a proper marker of the oxidative DNA damage. In another experiment, the mice were sacrificed and lungs were isolated 4 h after the instillation with vehicle or CSBG for evaluation of transcriptional level of heme oxygenase (HO)-1, a stress responsive protein. Pulmonary exposure to CSBG significantly induced apoptosis and enhanced the formation of 8-OHdG in the lung parenchyma as compared to vehicle or DEG-CSBG exposure. CSBG significantly induced HO-1 in the lung. Taken together, CSBG induces/enhances apoptosis and oxidative stress in the lung in association with lung inflammation/injury.

Pulmonary exposure to soluble cell wall beta-(1, 3)-glucan of aspergillus induces proinflammatory response in mice

Compared to the significant immunomodulation of cell wall component(s) of bacterium such as lipopolysaccharide (E. Coli), that of pathogenic fungi has not been well elucidated, especially in vivo. Furthermore, although it has been implied that beta-(1, 3)-glucan of fungi possesses various biological activities, the impacts of the component have not been properly clarified, possibly due to its insolubility in water and alkali solutions. Previously, we isolated a soluble type of beta-(1, 3) -glucan from Aspergillus (referred to as ASBG). The present study investigated the effects of a single pulmonary exposure to ASBG on the immune (proinflammatory) responses in naïve mice. ASBG (12.5-100micorg/animal) exposure Induced neutrophilic lung inflammation with an enhanced local expression of proinflammatory cytokines such as interleukin (IL)-1beta and chemokines such as macrophage inflammatory protein -1a, and keratinocyte-derived chemoattractant in a dose-dependent fashion with overall trends. On the other hand, ASBG at relatively lower doses significantly amplified the lung expression of IL-2, IL-6, and IL-12 as compared with vehicle. ASBG significantly induced pulmonary edema. Furthermore, ASBG augmented the nuclear translocation of nuclear factor (NF)-kB and its binding capacity to the promoter site of DNA in the lung homogenate. These results suggest that pulmonary exposure to ASBG confers lung inflammation, at least partly, via the enhanced local expression of proinflammatory cytokines, likely through NF-kB-dependent pathway.

Central venous catheter-associated fungemia due toRhodotorulaspp. – A systematic review

Rhodotorula spp. are emergent opportunistic pathogens, particularly in immunocompromised individuals. They have been associated with endocarditis, peritonitis, meningitis endophthalmitis and catheter-associated fungemia. The aim of this study was to review all cases of central venous catheter-related fungemia due to Rhodotorula spp. reported in the literature in order to determine the best management of this uncommon infection. All patients but one in the 88 cases examined had some form of underlying disease including sixty-nine (78.4%) who had cancer. Rhodotorula mucilaginosa was the species most frequently recovered (75%), followed by Rhodotorula glutinis (6%). Amphotericin B deoxycholate was the most common antifungal agent used as treatment and the overall mortality was 9.1% in this review. This fungemia is a rare disease which can be found in immunocompromised and in the intensive care patients. The use of specific antifungal therapy may be associated with an increase in the survival. It should be noted that Rhodotorula spp. is resistant to fluconazole.

Central venous catheter-related infection due to Candida membranaefaciens, a new opportunistic azole-resistant yeast in a cancer patient: a case report and a review of literature

An unusual central venous catheter (CVC)-related infection caused by Candida membranaefaciens in a patient with non-Hodgkin's lymphoma is described. Clinical signs and microbiological results observed in this case may support the hypothesis of an emerging CVC-related fungaemia, because of new azole-resistant yeast, successfully treated with liposomal amphotericin B. To date C. membranaefaciens (the teleomorph of Pichia membranaefaciens) has traditionally been considered non-pathogenic and this report seems to be the first case of systemic fungal infection. We believe that another fungus can be added to the list of opportunistic strains.

Carboxylic acid and phosphate ester derivatives of fluconazole: synthesis and antifungal activities

Two classes of fluconazole derivatives, (a) carboxylic acid esters and (b) fatty alcohol and carbohydrate phosphate esters, were synthesized and evaluated in vitro against Cryptococcus neoformans, Candida albicans, and Aspergillus niger. All carboxylic acid ester derivatives of fluconazole (1a-l), such as O-2-bromooctanoylfluconazole (1g, MIC=111 microg/mL) and O-11-bromoundecanoylfluconazole (1j, MIC=198 microg/mL), exhibited higher antifungal activity than fluconazole (MIC > or = 4444 microg/mL) against C. albicans ATCC 14053 in SDB medium. Several fatty alcohol phosphate triester derivatives of fluconazole, such as 2a, 2b, 2f, 2g, and 2h, exhibited enhanced antifungal activities against C. albicans and/or A. niger compared to fluconazole in SDB medium. For example, 2-cyanoethyl-omega-undecylenyl fluconazole phosphate (2b) with MIC value of 122 microg/mL had at least 36 times greater antifungal activity than fluconazole against C. albicans in SDB medium. Methyl-undecanyl fluconazole phosphate (2f) with a MIC value of 190 microg/mL was at least 3-fold more potent than fluconazole against A. niger ATCC 16404. All compounds had higher estimated lipophilicity and dermal permeability than those for fluconazole. These results demonstrate the potential of these antifungal agents for further development as sustained-release topical antifungal chemotherapeutic agents.

Characterization of beta-glucan recognition site on C-type lectin, dectin 1

Dectin 1 is a mammalian cell surface receptor for (1-->3)-beta-d-glucans. Since (1-->3)-beta-d-glucans are commonly present on fungal cell walls, it has been suggested that dectin 1 is important for recognizing fungal invasion. In this study we tried to deduce the amino acid residues in dectin 1 responsible for beta-glucan recognition. HEK293 cells transfected with mouse dectin 1 cDNA could bind to a gel-forming (1-->3)-beta-d-glucan, schizophyllan (SPG). The binding of SPG to a dectin 1 transfectant was inhibited by pretreatment with other beta-glucans having a (1-->3)-beta-d-glucosyl linkage but not by pretreatment with alpha-glucans. Dectin 1 has a carbohydrate recognition domain (CRD) consisting of six cysteine residues that are highly conserved in C-type lectins. We prepared 32 point mutants with mutations in the CRD and analyzed their binding to SPG. Mutations at Trp(221) and His(223) resulted in decreased binding to beta-glucan. Monoclonal antibody 4B2, a dectin- 1 monoclonal antibody which had a blocking effect on the beta-glucan interaction, completely failed to bind the dectin-1 mutant W221A. A mutant with mutations in Trp(221) and His(223) did not have a collaborative effect on Toll-like receptor 2-mediated cellular activation in response to zymosan. These amino acid residues are distinct from residues in other sugar-recognizing peptide sequences of typical C-type lectins. These results suggest that the amino acid sequence W221-I222-H223 is critical for formation of a beta-glucan binding site in the CRD of dectin 1.

Enhanced phagocytosis of Candida species mediated by opsonization with a recombinant human antibody single-chain variable fragment

Specific antibody opsonization significantly enhances the level of phagocytosis of Candida in the absence of complement. Furthermore, we have described a system using a recombinant human antibody single-chain variable fragment that allows a comparative study of phagocytosis of multiple Candida species opsonized via a common antigen.

Bipolaris spicifera causes fungus balls of the sinuses and triggers polypoid chronic rhinosinusitis in an immunocompetent patient

We report the rare case of a 19-year-old immunocompetent male suffering both from fungus balls of the sinuses and from chronic rhinosinusitis with massive polyposis. Endoscopic sinus surgery revealed grayish brown necrotic masses embedded in viscous eosinophilic mucus. Inoculated onto petri dishes, these masses as well as the mucus grew a dark pigmented fungus, which was identified as Bipolaris spicifera.

Mucosal and Systemic Fungal Infections in Patients with AIDS

In countries where highly active antiretroviral therapy (HAART) is widely available, a decrease in the incidence of fungal infections has been observed in the last 5 years compared with countries that cannot afford this treatment. Even refractory fungal infections may be controlled when HAART is given to patients, and end-stage AIDS infections, such as aspergillosis, are now only infrequently seen. In contrast, fungal infections in certain regions, such as penicilliosis in Southeast Asia or cryptococcosis in Sub-Saharan Africa, are a growing problem. Antifungal therapy for documented infections has not changed very much during recent years; however, new drugs such as caspofungin and voriconazole may be more effective in the treatment of opportunistic fungal infections, in particular, those involving resistant organisms. Secondary antifungal prophylaxis for many opportunistic pathogens can now be temporarily or even permanently discontinued in many HIV-positive patients who have a marked improvement in immune function parameters, such as CD4(+) cell counts, after initiation of HAART. The link between effective virustatic control of HIV infection and a decreasing incidence of fungal infections has been recognised; and so, despite the availability of very effective new antifungal drugs, the cornerstone of treatment and prevention of opportunistic fungal infections in patients with HIV infection is effective antiretroviral therapy including protease inhibitors.

Fungal peritonitis caused byBipolaris spicifera

An episode of fungal peritonitis was produced by Bipolaris spicifera in a 3-year-old girl with chronic renal failure secondary to uremic-hemolytic syndrome and who was under treatment with continuous ambulatory peritoneal dialysis (CAPD). Previously, an episode of purulent peritonitis caused by Pseudomonas spp. had been treated successfully with combined antibacterial therapy for 10 days. Microscopic and macroscopic examinations of the freshly collected purulent dialysate were negative for fungal structures and bacteria. The fungus grew from the dialysate plated on Sabouraud dextrose agar and was also macroscopically recognized as a colony attached to the inner wall of the Tenckhoff catheter. Specific cultures of dialysate for common bacteria and mycobacteria were negative. The patient was successfully treated with early catheter removal and empirical administration of 200 mg/day oral fluconazole for 2 weeks. Subsequently, a new catheter was placed and the patient continued well on CAPD. Post-treatment control cultures of dialysate for fungi, bacteria and mycobacteria were negative and the cell count returned to normal.

Non-albicans Candida spp. causing fungaemia: pathogenicity and antifungal resistance

Non-albicans Candida (NAC) species cause 35-65% of all candidaemias in the general patient population. They occur more frequently in cancer patients, mainly in those with haematological malignancies and bone marrow transplant (BMT) recipients (40-70%), but are less common among intensive care unit (ITU) and surgical patients (35-55%), children (1-35%) or HIV-positive patients (0-33%). The proportion of NAC species among Candida species is increasing: over the two decades to 1990, NAC represented 10-40% of all candidaemias. In contrast, in 1991-1998, they represented 35-65% of all candidaemias. The most common NAC species are C. parapsilosis (20-40% of all Candida species), C. tropicalis (10-30%), C. krusei (10-35%) and C. glabrata (5-40%). Although these four are the most common, at least two other species are emerging: C. lusitaniae causing 2-8% of infections, and C. guilliermondii causing 1-5%. Other NAC species, such as C. rugosa, C. kefyr, C. stellatoidea, C. norvegensis and C. famata are rare, accounting for less than 1% of fungaemias in man. In terms of virulence and pathogenicity, some NAC species appear to be of lower virulence in animal models, yet behave with equal or greater virulence in man, when comparison is made with C. albicans. Mortality due to NAC species is similar to C. albicans, ranging from 15% to 35%. However, there are differences in both overall and attributable mortality among species: the lowest mortality is associated with C. parapsilosis, the highest with C. tropicalis and C. glabrata (40-70%). Other NAC species including C. krusei are associated with similar overall mortality to C. albicans (20-40%). Mortality in NAC species appears to be highest in ITU and surgical patients, and somewhat lower in cancer patients, children and HIV-positive patients. There is no difference between overall and attributable mortality, with the exception of C. glabrata which tends to infect immunocompromised individuals. While the crude mortality is low, attributable mortality (fungaemia-associated mortality) is higher than with C. albicans. There are several specific risk factors for particular NAC species: C. parapsilosis is related to foreign body insertion, neonates and hyperalimentation; C. krusei to azole prophylaxis and along with C. tropicalis to neutropenia and BMT; C. glabrata to azole prophylaxis, surgery and urinary or vascular catheters; C. lusitaniae and C. guilliermondii to previous polyene (amphotericin B or nystatin) use; and C. rugosa to burns. Antifungal susceptibility varies significantly in contrast to C. albicans: some NAC species are inherently or secondarily resistant to fluconazole; for example, 75% of C. krusei isolates, 35% of C. glabrata, 10-25% of C. tropicalis and C. lusitaniae. Amphotericin B resistance is also seen in a small proportion: 5-20% of C. lusitaniae and C. rugosa, 10-15% of C. krusei and 5-10% of C. guilliermondii. Other NAC species are akin to C. albicans-susceptible to both azoles and polyenes (C. parapsilosis, the majority of C. guilliermondii strains and C. tropicalis). Therefore, 'species directed' therapy should be administered for fungaemia according to the species identified-amphotericin B for C. krusei and C. glabrata, fluconazole for other species, including polyene-resistant or tolerant Candida species (C. lusitaniae, C. guilliermondii). In vitro susceptibility testing should be performed for most species of NAC in addition to removal of any foreign body to optimize management.

Nosocomial bloodstream infections among human immunodeficiency virus-infected patients: incidence and risk factors

To assess the incidence of nosocomial bloodstream infections (NBSIs) in human immunodeficiency virus (HIV)-infected patients, and to analyze the main associated risk factors, we performed a 1-year multicenter prospective study of patients with advanced HIV infection who were consecutively admitted to 17 Italian infectious diseases wards. As of May 1999, a total of 65 NBSIs (4.7%) occurred in 1379 admissions, for an incidence of 2.45 NBSIs per 1000 patient-days. Twenty-nine NBSIs were catheter-related bloodstream infections, with a rate of 9.6 central venous catheter-associated infections per 1000 device-days. Multivariate analysis indicated that variables independently associated with NBSIs included active injection drug use, a Karnofsky Performance Status score of <40, presence of a central venous catheter, and length of hospital stay. Mortality rates were 24.6% and 7.2% among patients with and without NBSIs, respectively (P<.00001). In the era of highly active antiretroviral therapy, NBSIs continue to occur frequently and remain severe and life-threatening manifestations.

Strong antifungal activity of SS750, a new triazole derivative, is based on its selective binding affinity to cytochrome P450 of fungi

SS750 [(R)-(-)-2-(2,4-difluorophenyl)-1-(ethylsulfonyl)-1,1-difluoro-3-(1H-1,2,4-triazol-1-yl)-2-propanol] is a new triazole, and its potential as an antifungal agent was evaluated by in vitro and in vivo studies. In a comparison of the MICs at which 50% of isolates are inhibited (MIC(50)s) for all strains of Candida species and Cryptococcus neoformans tested, SS750 was four times or more active than fluconazole and had activity comparable to that of itraconazole. The most important advantage of SS750 was that, when the MIC(90)s were compared, SS750 had 64 and 32 times greater antifungal activities than fluconazole against Candida krusei and Candida glabrata, respectively, which are intrinsically less susceptible to fluconazole. In cyclophosphamide-immunosuppressed mouse models of systemic and pulmonary candidiasis caused by C. albicans, oral SS750 prolonged the number of days of survival of infected animals in a dose-dependent manner and was 4 and > or =64 times more potent than fluconazole and itraconazole, respectively. In a safety profile, SS750, like fluconazole, had less of an affinity for binding to mammalian cytochrome P450 compared with that of ketoconazole, despite its strong affinity for binding to fungal cytochrome P450. The mechanism for the increased in vitro antifungal activity of SS750 against C. krusei is partially due to the potent inhibitory activity (3.7 times versus that of fluconazole) of C. krusei cytochrome P450 sterol 14alpha-demethylase; SS750 showed a strong affinity for binding to cytochrome P450 of C. krusei, indicating that SS750 acts by inhibiting the cytochrome P450 sterol 14alpha-demethylase of fungal cells.

Efficacy of the echinocandin caspofungin against disseminated aspergillosis and candidiasis in cyclophosphamide-induced immunosuppressed mice

The in vivo efficacy of the echinocandin antifungal caspofungin acetate (caspofungin; MK-0991) was evaluated in models of disseminated aspergillosis and candidiasis in mice with cyclophosphamide (CY)-induced immunosuppression. Caspofungin is a 1, 3-beta-D-glucan synthesis inhibitor efficacious against a number of clinically relevant fungi including Aspergillus and Candida species. Models of CY-induced transient or chronic leukopenia were used with once daily administration of therapy initiated 24 h after microbial challenge. Caspofungin was effective in treating disseminated aspergillosis in mice that were transiently leukopenic (significant prolongation of survival at doses of > or =0.125 mg/kg of body weight and a 50% protective dose [PD(50)] of 0.245 mg/kg/day at 28 days after challenge) or chronically leukopenic (50 to 100% survival at doses of > or =0.5 mg/kg and PD(50)s ranging from 0.173 to 0.400 mg/kg/day). Caspofungin was effective in the treatment and sterilization of Candida infections in mice with transient leukopenia with a 99% effective dose based on reduction in log(10) CFU of Candida albicans/gram of kidneys of 0.119 mg/kg and 80 to 100% of the caspofungin-treated mice having sterile kidneys at caspofungin doses from 0.25 to 2.0 mg/kg. In Candida-infected mice with chronic leukopenia, caspofungin was effective at all dose levels tested (0.25 to 1.0 mg/kg), with the log(10) CFU of C. albicans/gram of kidneys of caspofungin-treated mice being significantly lower (>99% reduction) than that of sham-treated mice from day 4 to day 28 after challenge. Also, 70 to 100% of the caspofungin-treated, chronic leukopenic mice had sterile kidneys at caspofungin doses of 0.5 to 1.0 mg/kg from day 8 to 28 after challenge. Sterilization of Candida infections by caspofungin in the absence of host leukocytes provides compelling in vivo evidence for fungicidal activity against C. albicans. Further human clinical trials with caspofungin against serious fungal infections are in progress.

The immune compromised host in the twenty-first century: management of mucocutaneous infections

Infectious diseases encountered in dermatology have changed tremendously during the past few decades with the emergence of the immunocompromised host. This change is a result of the human immunodeficiency virus epidemic, use of immunomodulating drugs, bone marrow transplantation, increasing prevalence of diabetes mellitus, and an aging population. New pathogens have been discovered and new disorders have occurred. In the compromised host, infection can be more aggressive and widespread locally, be caused by opportunistic pathogens, and be disseminated hematogenously from or to the skin. The prevalence of nonmelanoma skin cancer has increased, and squamous cell carcinomas can be more aggressive with more rapid local growth as well as frequency of metastasis.

Opportunistic infections and other clinical manifestations of HIV disease in children

As the decade draws to a close, physicians can be cautiously optimistic about the prevention and treatment of opportunistic infections in children with HIV disease. As more children receive therapy with powerful antiretroviral regimens, fewer are likely to be at risk for opportunistic pathogens. The widespread use of protease inhibitor combination therapies has already resulted in a dramatic decrease in morbidity and mortality in the population of HIV-infected adults. The same effect has been seen at pediatric care centers throughout the United States. Clinicians caring for HIV-infected children are now considering the safety of discontinuing prophylactic therapies for children with sustained immunologic improvement on antiretroviral therapy. For children who remain at risk, prophylactic regimens for PCP and MAC have been shown to decrease the risk for these infections. Preventive regimens for several other opportunistic infections are also available. The understanding of the pathogenesis of HIV and many of the opportunistic pathogens has led to the development of a variety of efficacious therapies for these infections. Despite these advances, physicians can anticipate that HIV-infected children will continue to develop opportunistic infections and other related complications. Some children fail to respond to antiretroviral therapies, whereas others are unable to tolerate the complex medication regimens. Prophylactic therapies are not 100% protective and, despite improved treatments, few opportunistic infections are cured. Most require lifelong maintenance therapy in the absence of immune reconstitution. Drug interactions, complex dosing schedules, adverse side effects, and high costs further limit the efficacy of these therapies. The prophylaxis, diagnosis, and treatment of opportunistic infections are likely to remain integral components of HIV care for the near and distant future.

Case report of three Candida albicans infections detected at delivery

We report three similar cases of Candida albicans infections in neonates, at delivery. A retrospective study of the isolates was conducted to define the diversity of infective strains and their susceptibility to amphotericin B and fluconazole. Three neonates with fever, 'not doing well' at delivery had positive cultures for C. albicans. Samples were then taken from the mothers who did not exhibit any clinical symptoms of infection. Candida albicans strains isolated from both neonates and mothers were cultured, six colonies of each were typed by multilocus enzyme electrophoresis. The E-test method was used to determine the susceptibility of each colony to the two antifungals commonly used in this unit: amphotericin B and fluconazole. The initial isolates were composed of different types of strains. In the three cases, one of the mother types was found in the neonate isolates, leading us to suggest a vertical transmission of strains. All of the other types were distinct. All of the types were susceptible to amphotericin B, although three of them, one type isolated from a neonate and two types isolated from the mother, were resistant to fluconazole. The diversity of infective strains remains alarming and encourages the consideration of several colonies per isolate or several isolates, when it is possible, per infection case. This study also points out the need to survey the susceptibility of infective strains, since some of them appear soon to be resistant to fluconazole.

Emerging fungal pathogens: evolving challenges to immunocompromised patients for the twenty-first century

Opportunistic fungi have emerged during the past decade as important causes of morbidity and mortality in immunocompromised patients. Candida species constitute the third to fourth most common causes of nosocomial blood stream infections, and Aspergillus species have emerged as the most common infectious cause of pneumonic mortality in bone marrow/stem cell transplant recipients. Among HIV-infected patients, meningoencephalitis due to Cryptococcus neoformans ranks among the most common AIDS-defining infections. Hyaline septated filamentous fungi, such as Fusarium species, Acremonium species, Paecilomyces species, and Trichoderma species, are increasingly reported as causing invasive mycoses refractory to conventional therapy. Dematiaceous septated filamentous fungi, such as Pseudallescheria boydii, Bipolaris species, and Cladophialophora bantiana cause pneumonia, sinusitis, and CNS infection unresponsive to current therapy. An increasing number of different members of the class of Zygomycetes are reported as causing lethal infections, despite aggressive medical and surgical interventions. Yet the treatment for zygomycosis has not changed in approximately 40 years. The prevalence of the endemic mycoses, such as those due to Penicillium marneffei, Coccidioides immitis, and Histoplasma capsulatum, has been reported to expand rapidly in response to environmental exposures and increased numbers of vulnerable hosts in endemic regions of the world. Dermatophytoses are occurring with increasing prevalence and morbidity in elderly and immunocompromised patients. As we enter the next millennium, we may anticipate that emergent fungal infections will continue to develop in the settings of permissive environmental conditions, selective antifungal pressure, and an expanding population of immunocompromised hosts.

The epidemiology of candidemia in two United States cities: results of a population-based active surveillance

We conducted prospective, active population-based surveillance for candidemia (defined as any Candida species isolated from blood) in Atlanta and San Francisco (total population, 5.34 million) during 1992-1993. The average annual incidence of candidemia at both sites was 8 per 100,000 population. The highest incidence (75 per 100,000) occurred among infants </=1 year old. In 19% of patients, candidemia developed prior to or on the day of admission. Underlying medical conditions included cancer (26%), abdominal surgery (14%), diabetes mellitus (13%), and human immunodeficiency virus infection (10%). In 47% of cases, species of Candida other than Candida albicans were isolated, most commonly Candida parapsilosis, Candida glabrata, and Candida tropicalis. Antifungal susceptibility testing of 394 isolates revealed minimal levels of azole resistance among C. albicans, C. tropicalis, and C. parapsilosis. These data document the substantial burden of candidemia and its changing epidemiology. Continued surveillance will be important to monitor the epidemiology of candidemia and to detect emergence of resistance to azoles.

Genotypic relatedness of yeast isolates from women infected with human immunodeficiency virus and their children

The objective of this study was to compare polymerase chain reaction (PCR) fingerprinting with other molecular typing methods as an epidemiologic tool to investigate the transmission of Candida strains between HIV-positive mothers and their children. Forty-nine yeast strains (including Candida albicans, Candida glabrata, Rhodotorula rubra, Candida tropicalis, Candida famata, Candida dubliniensis, Saccharomyces cerevisiae) from 30 individuals (15 children and 15 HIV-infected mothers or accompanying person) were isolated. Colonization/infection with yeast was observed in 80% of all individuals in the oral cavity, and in 33% from hand cultures, respectively. Thirteen out of 15 children (86%) and 12 out of 15 adults (80%) were colonized/infected with yeasts. Candida dubliniensis strains were found in four HIV-infected women but not in children. The results with an arbitrarily primed (AP)-PCR mediated genotyping assay using phage M13 core sequence were compared with the hybridization patterns using the species-specific DNA probe CARE-2 for the C. albicans isolates. Typing of non-C. albicans strains was done using AP-PCR in comparison with pulsed-field gel electrophoresis (PFGE). Twenty-six C. albicans strains gave two different genotypes by AP-PCR but 16 genotypes by CARE-2 hybridization. The CARE-2 probe appeared to have a higher discriminatory power compared with the primer 'M13'-mediated AP-PCR in typing C. albicans isolates.

Amphotericin B lipid complex in pediatric patients with invasive fungal infections

BACKGROUND

Lipid formulations of amphotericin B have been recently introduced for treatment of invasive fungal infections. However, little is known about their role in pediatric populations.

METHODS

We studied the safety and antifungal efficacy of amphotericin B lipid complex (ABLC, Abelcet) in 111 treatment episodes in pediatric patients through an open label, emergency use multicenter study. Patients with invasive fungal infections were enrolled if they had mycoses refractory to conventional antifungal therapy, if they were intolerant of previous systemic antifungal agents or concomitant nephrotoxic drugs or if they had preexisting renal disease.

RESULTS

All 111 treatment episodes were evaluable for safety and 54 were evaluable for efficacy. The mean serum creatinine for the study population did not significantly change between baseline (1.23 +/- 0.11 mg/dl) and cessation of ABLC therapy (1.32 +/- 0.12 mg/dl) during 6 weeks. There were no significant differences observed between initial and end-of-therapy levels of serum potassium, magnesium, aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase and hemoglobin. However, there was an increase in mean total bilirubin (3.66 +/- 0.73 to 5.31 +/- 1.09 mg/dl) at the end of therapy (P = 0.054). Among 54 cases fulfilling criteria for evaluation of antifungal efficacy, a complete or partial therapeutic response was obtained in 38 patients (70%) after ABLC therapy. Complete or partial therapeutic response was documented in 56% of cases with aspergillosis (n = 25) and in 81% (n = 27) with candidiasis. Among premature infants (n = 8) and allogeneic marrow recipients (n = 14), response rates were 88 and 57%, respectively. Response was similar in those patients enrolled because of intolerance to previous antifungal therapy or because of progressive infection.

CONCLUSIONS

These data support the use of ABLC for treatment of invasive fungal infections in pediatric patients who are intolerant of or refractory to conventional antifungal therapy.

Administration of fluconazole in children below 1 year of age

For this review, 78 studies regarding the use of fluconazole in a total of 726 children below 1 year of age were evaluated. The range of fluconazole dosage was 2-50 mg kg-1 day-1, with 162 days being the maximum duration of treatment. According to current experience, fluconazole seems to be well tolerated and efficacious against systemic candidosis and candidaemia in children below 1 year of age, including neonates and very low-birthweight infants (VLBWIs). The recommended daily dosage is 6 mg kg-1. (In Germany, fluconazole is approved for children between 1 and 16 years in cases in which there is no therapeutic alternative for treatment of systemic infections caused by Candida spp. and Cryptococcus neoformans in a dosage of 3-6 mg kg-1 day-1 and for superficial Candida infections in a dosage of 1-2 mg kg-1 day-1.) In patients with impaired renal function, the daily dose should be reduced in accordance with the guidelines given for adults. In neonates during the first 2 weeks of life, this dosage should be administered only every 72 h. In weeks 2-4 of life, the same dose should be given every 48 h, following which daily dosing is appropriate. This posology is derived from the age-related pharmacokinetics of fluconazole, with a higher volume of distribution and a prolonged plasma elimination half-life, especially during the first month of life. Drug monitoring during treatment should be performed to ensure therapeutic plasma concentrations of fluconazole within a range between 4 and 20 micrograms ml-1. The benefit of fluconazole should be investigated in prospective studies for treatment of systemic candidosis with administration of higher dosages as well as for early empiric therapy in VLBWIs.

Comparison of In vitro activities of the new triazole SCH56592 and the echinocandins MK-0991 (L-743,872) and LY303366 against opportunistic filamentous and dimorphic fungi and yeasts

The in vitro antifungal activities of SCH56592, MK-0991, and LY303366 against 83 isolates of Acremonium strictum, Aspergillus flavus, Aspergillus fumigatus, Aspergillus terreus, Bipolaris spp., Blastomyces dermatitidis, Cladophialophora bantiana, Fusarium oxysporum, Fusarium solani, Histoplasma capsulatum, Phialophora spp., Pseudallescheria boydii, Rhizopus arrhizus, Scedosporium prolificans, and Sporothrix schenckii were compared. The in vitro activities of these agents against 104 isolates of yeast pathogens of Candida spp., Cryptococcus neoformans, and Trichosporon beigelii were also compared. MICs were determined by following a procedure under evaluation by the National Committee for Clinical Laboratory Standards (NCCLS) for broth microdilution testing of the filamentous fungi (visual MICs) and the NCCLS M27-A broth microdilution method for yeasts (both visual and turbidimetric MICs). The in vitro fungicidal activity of SCH56592 was superior (minimum fungicidal concentrations [MFCs], 0.25 to 4 microgram/ml for 7 of 18 species tested) to those of MK-0991 and LY303366 (MFCs, 8 to >16 microgram/ml for all species tested) for the molds tested, but the echinocandins had a broader spectrum of fungicidal activity (MFCs at which 90% of strains are inhibited [MFC90s], 0.5 to 4 microgram/ml for 6 of 9 species tested) than SCH56592 (MFC90s, 0.25 to 8 microgram/ml for 4 of 9 species tested) against most of the yeasts tested. Neither echinocandin had in vitro activity (MICs, >16 microgram/ml) against C. neoformans and T. beigelii, while the SCH56592 MICs ranged from 0.12 to 1.0 microgram/ml for these two species. The MICs of the three agents for the other species ranged from <0.03 to 4 microgram/ml. These results suggest that these new agents have broad-spectrum activities in vitro; their effectiveness in the treatment of human mycoses is to be determined.

[Use of fluconazole in children less than 1 year old: review]

For this review, 78 publications for use of fluconazole in children below 1 year of age were evaluated with a total of 726 patients. The range of fluconazole dosage was 2-50 mg/kg/day with 162 days as maximum duration of treatment. According to the present experience, fluconazole seems to be an efficacious and well tolerated therapy against systemic candidosis and candidemia in children below 1 year of age, including neonates and very low birth-weight infants (VLBWI). The recommended daily dosage is 6 mg/kg. In patients with impaired renal function, the daily dose should be reduced in accordance with the guidelines given for adults. In neonates during the first two weeks of life, this dosage should be administered only every 72 hours. In weeks two to four of life, the same dose should be given every 48 hours. After that daily dosing is appropriate. This posology is derived from the age-related pharmacokinetics of fluconazole with a higher volume of distribution and a prolonged plasma elimination half life especially during the first month of life. Drug monitoring during treatment should be performed to ensure therapeutic plasma concentrations of fluconazole within a range between 4 and 20 micrograms/ml. The benefit of fluconazole should be investigated in prospective studies for treatment of systemic candidosis with administration of higher dosages as well as for early empiric therapy in VLBWI.

In vitro activity of the new triazole voriconazole (UK-109,496) against opportunistic filamentous and dimorphic fungi and common and emerging yeast pathogens

The in vitro antifungal activity of a new triazole derivative, voriconazole, was compared with those of itraconazole and amphotericin B against 67 isolates of Aspergillus flavus, Aspergillus fumigatus, Bipolaris spp., Fusarium oxysporum, Fusarium solani, Pseudallescheria boydii, Rhizopus arrhizus, Blastomyces dermatitidis, Histoplasma capsulatum, and Sporothrix schenckii. The in vitro activities of voriconazole were also compared with those of amphotericin B, fluconazole, and itraconazole against 189 isolates of emerging and common yeast pathogens of Blastoschizomyces capitatus, Candida (13 species), Cryptococcus neoformans, Hansenula anomala, Rhodotorula rubra, Saccharomyces cerevisiae, Sporobolomyces salmonicolor, and Trichosporon beigelii. MICs were determined according to a procedure under evaluation by the National Committee for Clinical Laboratory Standards (NCCLS) for broth microdilution testing of filamentous fungi and by the NCCLS M27-A broth microdilution method for yeasts. The in vitro activities of voriconazole were similar to or better than those of itraconazole and amphotericin B against Aspergillus spp., Fusarium spp., and P. boydii as well as against B. dermatitidis and H. capsulatum. The activities of voriconazole were also comparable to or better than those of amphotericin B, fluconazole, and itraconazole against most species of yeasts tested. Exceptions were certain isolates of R. rubra and S. salmonicolor. These results suggest that voriconazole has a wide spectrum of activity in vitro; its effectiveness in the treatment of human mycoses is under evaluation in clinical trials.

Antifungal prophylaxis during neutropenia and immunodeficiency

Fungal infections represent a major source of morbidity and mortality in patients with almost all types of immunodeficiencies. These infections may be nosocomial (aspergillosis) or community acquired (cryptococcosis), or both (candidiasis). Endemic mycoses such as histoplasmosis, coccidioidomycosis, and penicilliosis may infect many immunocompromised hosts in some geographic areas and thereby create major public health problems. With the wide availability of oral azoles, antifungal prophylactic strategies have been extensively developed. However, only a few well-designed studies involving strict criteria have been performed, mostly in patients with hematological malignancies or AIDS. In these situations, the best dose and duration of administration of the antifungal drug often remain to be determined. In high-risk neutropenic or bone marrow transplant patients, fluconazole is effective for the prevention of superficial and/or systemic candidal infections but is not always able to prolong overall survival and potentially selects less susceptible or resistant Candida spp. Primary prophylaxis against aspergillosis remains investigative. At present, no standard general recommendation for primary antifungal prophylaxis can be proposed for AIDS patients or transplant recipients. However, for persistently immunocompromised patients who previously experienced a noncandidal systemic fungal infection, prolonged suppressive antifungal therapy is often indicated to prevent a relapse. Better strategies for controlling immune deficiencies should also help to avoid some potentially life-threatening deep mycoses. When prescribing antifungal prophylaxis, physicians should be aware of the potential emergence of resistant strains, drug-drug interactions, and the cost. Well-designed, randomized, multicenter clinical trials in high-risk immunocompromised hosts are urgently needed to better define how to prevent severe invasive mycoses.

Invasive candidosis in pediatric patients

OBJECTIVE: To analyze invasive Candida infections in pediatric patients and to examine the outcome of disease. METHODS: An observational prospective study was carried out of microbiologically documented cases of invasive candidosis in neonates, infants and children at Hippokration Hospital from December 1993 to July 1995. RESULTS: Thirty-nine cases of invasive candidosis (mainly candidemia and candiduria) occurred in 38 patients aged 3 days to 14 years, 21 (54%) having occurred in patients aged <1 month. The incidence was 10.1/1000 admissions in the two neonatal departments versus 1.1/1000 for all other pediatric departments, including oncology (p<0.01). The most frequent causes of hospitalization were premature birth or perinatal problems and surgery. Thirty-five strains of Candida albicans, 10 of C. parapsilosis and eight of other or unidentified species were isolated. Non-C. albicans isolates, especially C. parapsilosis and C. glabrata, exhibited higher minimal inhibitory concentrations of azoles as compared with C. albicans. Thirteen patients (34%), all candidemic, died within 0--40 days. Untreated patients more frequently had positive cultures up to time of death (p<0.0001) and died (p=0.0006). CONCLUSIONS: Invasive candidosis is frequent in pediatric patients, especially premature neonates, and is associated with increased mortality. With early diagnosis and initiation of therapy the outcome is favorable.