The epidemiology of Candida glabrata and Candida albicans fungemia in immunocompromised patients with cancer

Genotypic, phenotypic, and proteomic characterization of Candida glabrata during sequential fluconazole exposure

AIM

Candida glabrata is a major pathogen in humans known to be intrinsically resistant to fluconazole. However, genotypic, phenotypic, and proteomic changes associated with reduced susceptibility to fluconazole are not properly understood. The aim of this study was to observe specific phenotypic, chromosomal, and proteomic alterations in a Candida glabrata strain sequentially exposed to fluconazole.

METHODS

Candida glabrata was exposed to increased concentrations of fluconazole in RPMI for 55 days. Phenotypic changes were evaluated using standard assays. Molecular/proteomic changes in C. glabrata were analyzed by contour-clamped homogeneous electric field electrophoresis, reverse transcription-polymerase chain reaction, and mass spectrometry.

RESULTS

  Candida glabrata demonstrated increased fluconazole resistance (>256 μg/mL), with extensive cross-resistance to ketoconazole (0.38-3.0 μg), itraconazole (8 to >32 μg), and voriconazole (0.125-1.5 μg). Morphologically dissimilar colonies on RPMI/fluconazole agar demonstrated variable chromosomal profiles compared with the control isolate. Stable chromosomal changes were associated with a significantly higher (P<0.05) mRNA level of the hemolysin gene compared with the control. Phenotypic switching on CuSO4 agar was associated with variable metallothionein mRNA transcription levels. The proteome analysis of a fluconazole-resistant offshoot demonstrated a total of 98 protein spots, 25 showing a twofold upregulation.

CONCLUSION

Fluconazole exposure initiates the chance evolution of a new colonizing population with specific virulence traits.

In vitro antifungal susceptibilities of Candida isolates from patients with invasive candidiasis in Kuala Lumpur Hospital, Malaysia

The in vitro antifungal susceptibilities of 159 clinical isolates of Candida species from patients with invasive candidiasis in Kuala Lumpur Hospital, Malaysia, were determined against amphotericin B, fluconazole, voriconazole, itraconazole and caspofungin. The most common species were Candida albicans (71 isolates), Candida parapsilosis (42 isolates), Candida tropicalis (27 isolates) and Candida glabrata (12 isolates). The susceptibility tests were carried out using an E-test. The MIC breakpoints were based on Clinical Laboratory Standards Institute criteria. Amphotericin B and voriconazole showed the best activities against all the isolates tested, with MIC(90) values of ≤1 µg ml(-1) for all major species. Only one Candida lusitaniae isolate was resistant to amphotericin B, and all the isolates were susceptible to voriconazole. In total, six isolates were resistant to fluconazole, comprising two isolates of C. albicans, two of C. parapsilosis, one C. tropicalis and one C. glabrata, and all of these isolates showed cross-resistance to itraconazole. The MIC(90) of itraconazole was highest for C. glabrata and C. parapsilosis. Caspofungin was active against most of the isolates except for five isolates of C. parapsilosis. The MIC(90) of caspofungin against C. parapsilosis was 3 µg ml(-1). In conclusion, amphotericin B remains the most active antifungal agent against most Candida species except for C. lusitaniae. Voriconazole is the best alternative for fluconazole- or itraconizole-resistant isolates. Although five of the C. parapsilosis isolates showed in vitro resistance to caspofungin, more clinical correlation studies need to be carried out to confirm the significance of these findings. Currently, despite the increase in usage of antifungals in our hospitals, especially in the management of febrile neutropenia patients, the antifungal-resistance problem among clinically important Candida isolates in Kuala Lumpur Hospital is not yet worrying. However, continued antifungal-susceptibility surveillance needs to be conducted to monitor the antifungal-susceptibility trends of Candida species and other opportunistic fungal pathogens.

Predictors of candidaemia caused by non-albicans Candida species: results of a population-based surveillance in Barcelona, Spain

Although Candida albicans (CA) is the most common cause of Candida bloodstream infections (BSIs), recent studies have observed an increasing percentage of candidaemias caused by non-albicans Candida species (NAC). In the present study, we attempted to identify the predictors of candidaemia due to NAC compared to CA. We analyzed data from an active population-based surveillance in Barcelona (Spain) from January 2002 to December 2003. Factors associated with NAC fungaemia were determined by multivariate analysis. A total of 339 episodes of Candida BSI, in 336 patients (median age 63 years, interquartile range: 41-72 years), were included. CA was the most commonly isolated (52%), followed by Candida parapsilosis (23%), Candida tropicalis (10%), Candida glabrata (8.6%), Candida krusei (3.4%) and other NAC spp. (3%).Overall, 48% of cases were due to NAC spp. Multivariate logistic regression analysis identified factors associated with a risk of BSI due to NAC spp.: having received a haematologic transplant (OR 10.8; 95% CI 1.31-90.01; p 0.027), previous fluconazole exposure (OR 4.47; 95% CI 2.12-9.43; p <0.001) and neonatal age (OR 4.42; 95% CI 1.63-12.04; p 0.004). Conversely, previous CA colonization (OR 0.33; 95% CI 0.19-0.57; p 0.001) and previous antibiotic use (OR 0.42; 95% CI 0.21-0.85; p 0.017) were associated with CA fungaemia compared to NAC. In conclusion, NAC candidaemia comprised 48% of cases in our series. Predictors of NAC include having received a haematologic transplant, neonatal age and previous fluconazole use.

Antifungal prophylaxis and therapy in patients with hematological malignancies and hematopoietic stem cell transplant recipients

Patients with acute leukemia and hematopoietic stem cell transplant recipients are at risk of a spectrum of invasive fungal diseases corresponding to the type and intensity of immunosuppression. The development of newer antifungal agents has broadened therapeutic options. In the 1990s, lipid formulations of amphotericin B became widely used as safer alternatives to amphotericin B deoxycholate. In addition, fluconazole was shown to be beneficial as a yeast-active prophylaxis in hematopoietic stem cell transplant recipients. In the past decade, the antifungal armamentarium was further enhanced with the availability of extended-spectrum azoles and echinocandins. The development of effective broad-spectrum antifungal agents has led to their use as prophylaxis rather than delaying treatment until clinical signs of infection manifest. Antigen-based and PCR-based diagnostic adjuncts facilitate earlier detection of invasive fungal diseases compared with conventional culture, and have been incorporated into strategies in which initiation or modification of an antifungal regimen is targeted to patients with the highest likelihood of having fungal disease. Here, we review the pharmacological data and major clinical trials that guide the use of antifungals, as well as areas of uncertainty and future perspectives.

Invasive Candida infections in patients with haematological malignancies and hematopoietic stem cell transplant recipients: current epidemiology and therapeutic options

In the last decades, the global epidemiological impact of invasive candidiasis (IC) in patients with hematologic malignancies (HM) and in hematopoietic stem cell transplant (HSCT) recipients has decreased and the incidence of invasive aspergillosis exceeded that of Candida infections. The use of prevention strategies, first of all antifungal prophylaxis with triazoles, contributed to the reduction of IC in these populations as demonstrated by several epidemiological studies. However, relatively little is known about the current epidemiological patterns of IC in HM and HSCT populations, because recent epidemiological data almost exclusively derive from retrospective experiences and few prospective data are available. Several prospective, controlled studies in the prophylaxis of invasive fungal diseases have been conducted in both the HM and HSCT setting. On the contrary, most of the prospective controlled trials that demonstrated the efficacy of the antifungal drugs echinocandins and voriconazole in the treatment of candidemia and invasive candidiasis mainly involved patients with underlying conditions other than HM or HSCT. For these reasons, international guidelines provided specific indications for the prophylaxis strategies in HM and HSCT patients, whereas the recommendations on therapy of documented Candida infections are based on the results observed in the general population and should be considered with caution.

Glycosylation status of the C. albicans cell wall affects the efficiency of neutrophil phagocytosis and killing but not cytokine signaling

The cell wall of the opportunistic human fungal pathogen, Candida albicans is a complex, layered network of rigid structural polysaccharides composed of β-glucans and chitin that is covered with a fibrillar matrix of highly glycosylated mannoproteins. Polymorphonuclear cells (PMNs, neutrophils) are the most prevalent circulating phagocytic leukocyte in peripheral blood and they are pivotal in the clearance of invading fungal cells from tissues. The importance of cell-wall mannans for the recognition and uptake of C. albicans by human PMNs was therefore investigated. N- and O-glycosylation-deficient mutants were attenuated in binding and phagocytosis by PMNs and this was associated with reduced killing of C. albicans yeast cells. No differences were found in the production of the respiratory burst enzyme myeloperoxidase (MPO) and the neutrophil chemokine IL-8 in PMNs exposed to control and glycosylation-deficient C. albicans strains. Thus, the significant decrease in killing of glycan-deficient C. albicans strains by PMNs is a consequence of a marked reduction in phagocytosis rather than changes in the release of inflammatory mediators by PMNs.

Prevalence and antifungal resistance profile of Candida spp. oral isolates from patients with type 1 and 2 diabetes mellitus

OBJECTIVE

The goal of the study was to measure the prevalence of Candida spp. in the oral cavity of patients with diabetes types 1 and 2 when compared to healthy individuals and to study antifungal resistance profile of the isolates.

DESIGN

There were 162 subjects in the study: diabetes type 1 (n=39); control group 1 (n=50): healthy individuals matched in gender, age, and oral conditions to diabetes type 1 patients; diabetes type 2 (n=37); control group 2 (n=36) who were matched to each patient of the diabetes type 2 group. Stimulated saliva was collected and isolates were identified with phenotypic tests. The presence of C. dubliniensis was determined by multiplex PCR.

RESULTS

There were no statistically significant differences in Candida spp. frequency between the diabetes 1 group and its control (p=0.443) nor between the diabetes 2 group and its control (p=0.429). C. albicans was the most frequently isolated yeast in all groups. In the diabetes groups, C. stellatoidea, C. parapsilosis, C. tropicalis, C. lipolytica, C. glabrata, and C. krusei were also identified. Additionally, in control groups, C. kefyr was also detected. None of the isolates were resistant to amphotericin B and flucytosine. A low percentage of the isolates were resistant to ketoconazole.

CONCLUSIONS

No differences were detected in colonization of Candida spp. oral isolates from type 1 and type 2 diabetes when compared to matched controls. The antifungal resistance of Candida spp. isolates for ketoconazole from type 1 diabetes patients was significantly higher than that of its matched control.

Enzymatic activity, sensitivity to antifungal drugs and Baccharis dracunculifolia essential oil by Candida strains isolated from the oral cavities of breastfeeding infants and in their mothers' mouths and nipples

Candida strains can cause oral candidosis, as well as nipples candidosis and lead to premature weaning or yeast transmission. The aim of this study was to evaluate 51 Candida isolates obtained from the oral cavities of infants during breastfeeding and mothers' oral cavities and nipples, their enzymatic activity and their sensitivity to amphotericin B, fluconazole and Baccharis dracunculifolia essential oil. Among the studied strains, 96.1% produced phospholipase and 78.4% produced proteinase. The antifungal resistance was only observed among isolates of C. albicans, for which three strains showed a resistant activity to fluconazole and one showed a resistant activity to amphotericin B. All strains were sensitive to B. dracunculifolia essential oil with MIC between 0.2 and 6.25 mg/ml. It was concluded that most of the strains showed significant enzymatic activity and were sensitive to amphotericin B and fluconazole. B. dracunculifolia essential oil inhibited the growth of all strains, including the ones resistant to commercial antifungal agents.

SYK kinase signaling and the NLRP3 inflammasome in antifungal immunity

Host protection against fungi depends on intact innate and adaptive immune responses. Consistently, fungal infections can cause systemic life-threatening diseases in immunocomprimised individuals, suffering e.g. from cancer or AIDS. Recent work has uncovered essential roles for the spleen tyrosine kinase (SYK) and the cytosolic NLRP3 inflammasome for Interleukin-1beta (IL-1beta) production in innate antifungal immunity. Upon fungal infection, SYK is activated by several C-type lectin pattern recognition receptors on myeloid cells. Subsequently, SYK signals for the production of reactive oxygen species and for gene transcription to induce pro-inflammatory factors, including pro-IL-1beta to initiate antifungal responses. Mature IL-1beta production additionally requires cleavage of the pro-IL-1beta precursor protein by the inflammatory caspase-1 which is controlled within the NLRP3 inflammasome. Here, we discuss how SYK signaling cooperates with the NLRP3 inflammasome for IL-1beta production in antifungal immunity.

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.

Megasatellites: a new class of large tandem repeats discovered in the pathogenic yeast Candida glabrata

Megasatellites are DNA tandem arrays made of large motifs; they were discovered in the yeast Candida glabrata. They are widespread in this species (40 copies) but are not found in any other hemiascomycete so far, raising the intriguing question of their origin. They are found mainly in genes encoding cell wall products, suggesting that megasatellites were selected for a function linked to cell-cell adhesion or to pathogenicity. Their putative role in promoting genome rearrangements by interfering with DNA replication will also be discussed.

Nosocomial candidaemia in a Finnish tertiary care centre during 1987-2004

We studied the epidemiology of nosocomial candidaemia by assessing the incidence and outcome of illness and causative species in a large Finnish tertiary care centre during 1987-2004. A total of 364 episodes were observed; annual incidence varied between 0.26 per 10,000 patient-d in 2000 and 0.59 in 1989. The most common species were C. albicans (65%), C. parapsilosis (13%), and C. glabrata (9%). The proportion of C. albicans decreased from 71% during 1987-1992 to 58% during 1999-2004, and C. glabrata increased from 3% to 14%, respectively. The proportion of intensive care patients increased from 27% during 1987-1992 to 44% by 1999-2004, associated with neonates and surgical patients. The 1-month case fatality ranged from 30% to 33%. Nosocomial candidaemias did not increase, but the distribution of Candida spp. changed. Mortality remained high. The observed changes may reflect differences in prevention strategies that need to be explored for further improvements in prevention.

Candida albicans enhances experimental hepatic melanoma metastasis

Candida albicans infections are very frequent in cancer patients, whose immune system is often compromised, but whether this fungal pathogen affects cancer progression is unknown. C. albicans infection involves endogenous production of inflammatory cytokines such as tumour necrosis factor alpha (TNF-alpha) and interleukin-18 (IL-18). Increased levels of these cytokines have already been correlated with metastasis of most common cancer types. In this study, a well-established model of IL-18-dependent hepatic melanoma metastasis was used to study whether C. albicans can alter the ability of murine B16 melanoma (B16M) cells to colonize the liver. First, we determined the ability of intrasplenically (IS) injected B16M cells to metastasize into the liver of mice challenged with 5 x 10(4) C. albicans cells by three different routes (intravenous, IV; intrasplenic, IS; or intraperitoneal, IP) 12 h prior to injection of B16M cells. We demonstrated that C. albicans significantly increased metastasis of B16M cells with all three fungal injection routes. Pro-metastatic effects occurred when hepatic colonization with B16M cells place after the peak of TNF-alpha and IL-18 levels had been reached in the hepatic blood of fungal challenged mice. In a second set of experiments, mice were fungal challenged 4 days after injection of B16M cells. In these mice, C. albicans also potentiated the growth of established micro-metastases. Significantly, the fungal challenge had pro-metastatic effects without the C. albicans being able to reach the liver, suggesting that soluble factors can promote metastasis in remote sites. Mouse treatment with antifungal ketoconazol abrogated hepatic TNF-alpha stimulation by C. albicans and prevented the enhancement of hepatic metastasis in fungal challenged-mice. Therefore, the pro-inflammatory microenvironment generated by the host's systemic response to C. albicans stimulates circulating cancer cells to metastasize in the liver.

Effect of antifungal therapy timing on mortality in cancer patients with candidemia

Prior studies have shown that delays in treatment are associated with increased mortality in patients with candidemia. The purpose of this study was to measure three separate time periods comprising the diagnosis and treatment of candidemia and to determine which one(s) is associated with hospital mortality. Patients with blood cultures positive for Candida spp. were identified. Subjects were excluded if no antifungal therapy was given or if there was preexisting antifungal therapy. Collected data included the time from blood culture collection to positivity (incubation period), the time from blood culture positivity to provider notification (provider notification period), and the time from provider notification to the first dose of antifungal given (antifungal initiation period). These times were assessed as predictors of inpatient mortality. A repeat analysis was done with adjustments for age, sex, race, underlying cancer, catheter removal, APACHE III score, acute renal failure, neutropenia, and non-Candida albicans species. A total of 106 episodes of candidemia were analyzed. The median incubation time was 32.1 h and was associated with mortality (univariate hazard ratio per hour, 1.025; P = 0.001). The median provider notification and antifungal initiation periods were 0.3 and 7.5 h, respectively, and were not associated with mortality. Adjusted analysis yielded similar results. For cancer patients with candidemia, the incubation period accounts for a significant amount of time, compared with the provider notification and antifungal initiation times, and is associated with in-hospital mortality. Strategies to shorten the incubation time, such as utilizing rapid molecularly based diagnostic methods, may help reduce in-hospital mortality.

Invasive candidiasis: an overview from Taiwan

Invasive candidiasis has emerged as an important nosocomial infection, especially in critically ill patients. We review the epidemiology of invasive candidiasis with an emphasis on data from Taiwan. An increasing incidence of candidemia became apparent from 1980 to the end of the 1990s, followed by relative stability. Crude mortality rates of patients with candidemia were in the range of 35% to 60%. Candida albicans remains the predominant cause of invasive candidiasis in Taiwan and accounts for more than 50% of all cases. Candida tropicalis, Candida glabrata and Candida parapsilosis are the three most common non-albicans Candida species that cause invasive candidiasis. The above four Candida species account for more than 90% of invasive candidiasis in Taiwan. Overall, invasive Candida isolates have remained highly susceptible to fluconazole (> 90% susceptibility) over the past two decades. However, periodic surveillance is needed to monitor antifungal resistance because reduced fluconazole susceptibility in non-albicans Candida is not an uncommon trend. Voriconazole and echinocandins continue to exhibit excellent in vitro activity against invasive Candida isolates.

Approach to the immunocompromised host with infection in the intensive care unit

Despite significant advances in the prevention, diagnosis, and treatment of infection in the immunocompromised host, it remains a major cause of morbidity, increased length of stay, total costs, and of course mortality. Intensive care mortality rates are significantly higher among immunocompromised hosts in part due to the higher incidence of infection severity. The superimposition of the compromised host defenses and critical illness makes the detection and management of infections in such patients more difficult, but crucial toward salvaging patient outcome. Moreover, although there is a rapidly increasing evidence base in intensive care medicine, many interventional trials for the management of severe sepsis (activated protein C, adjunctive corticosteroids, goal-based resuscitation), acute lung injury (low stretch ventilation), and other organ failures have excluded immunocompromised hosts.

Blood stream infections by Candida glabrata and Candida krusei: a single-center experience

BACKGROUND/AIMS

The increasing incidence of Candida glabrata and Candida krusei infections is a significant problem because they are generally more resistant to fluconazole. We compared the risk factors associated with C. glabrata and C. krusei fungemia with Candida albicans fungemia and examined the clinical manifestations and prognostic factors associated with candidemia.

METHODS

We retrospectively reviewed demographic data, risk factors, clinical manifestations, and outcomes associated with C. glabrata and C. krusei fungemia at a tertiary-care teaching hospital during a 10-years period from 1997 to 2006.

RESULTS

During the study period, there were 497 fungemia episodes. C. glabrata fungemia accounted for 23 episodes and C. krusei fungemia accounted for 8. Complete medical records were available for 27 of these episodes and form the basis of this study. Compared to 54 episodes of C. albicans fungemia, renal insufficiency and prior fluconazole prophylaxis were associated with development of C. glabrata or C. krusei fungemia. The overall mortality was 67%. The fungemia-related mortality of C. glabrata and C. krusei was higher than that of C. albicans (52 vs. 26%, p=0.021). Empirical antifungal therapy did not decrease the crude mortality. Multiple logistic regression analysis showed that high APACHE II scores, catheter maintenance, and shock were independently associated with an increased risk of death.

CONCLUSIONS

Renal insufficiency and prior fluconazole prophylaxis were associated with the development of C. glabrata or C. krusei fungemia. Fungemia-related mortality of C. glabrata or C. krusei was higher than that of C. albicans. Outcomes appeared to be related to catheter removal, APACHE II scores, and shock.

Candidaemia with uncommon Candida species: predisposing factors, outcome, antifungal susceptibility, and implications for management

The risk factors for and clinical features of bloodstream infection with uncommon Candida spp. (species other than C. albicans, C. glabrata, C. parapsilosis, C. tropicals and C. krusei) are incompletely defined. To identify clinical variables associated with these species that might guide management, 57 cases of candidaemia resulting from uncommon Candida spp. were analysed in comparison with 517 episodes of Candida albicans candidaemia (2001-2004). Infection with uncommon Candida spp. (5.3% of candidaemia cases), as compared with C. albicans candidaemia, was significantly more likely to be outpatient-acquired than inpatient-acquired (15 of 57 vs. 65 of 517 episodes, p 0.01). Prior exposure to fluconazole was uncommon (n=1). Candida dubliniensis was the commonest species (n=22, 39%), followed by Candida guilliermondii (n=11, 19%) and Candida lusitaniae (n=7, 12%).C. dubliniensis candidaemia was independently associated with recent intravenous drug use (p 0.01) and chronic liver disease (p 0.03), and infection with species other than C. dubliniensis was independently associated with age<65 years (p 0.02), male sex (p 0.03) and human immunodeficiency virus infection (p 0.05). Presence of sepsis at diagnosis and crude 30-day mortality rates were similar for C. dubliniensis-related, non-C. dubliniensis-related and C. albicans-related candidaemia. Haematological malignancy was the commonest predisposing factor in C. guilliermondii (n=3, 27%) and C. lusitaniae (n=3, 43%) candidaemia. The 30-day mortality rate of C. lusitaniae candidaemia was higher than the overall death rate for all uncommon Candida spp. (42.9% vs. 25%, p not significant). All isolates were susceptible to amphotericin B, voriconazole, posaconazole, and caspofungin; five strains (9%) had fluconazole MIC values of 16-32 mg/L. Candidaemia due to uncommon Candida spp. is emerging among hospital outpatients; certain clinical variables may assist in recognition of this entity.

The Effects of Caspofungin and Voriconazole in Experimental Candida Endophthalmitis

PURPOSE

To evaluate the efficacy of newly developed antifungal agents caspofungin and voriconazole in Candida albicans endophthalmitis in rabbit eyes.

METHODS

Thirty New Zealand white rabbits were divided into four treatment groups and one control group. One eye of each rabbit was infected by inoculation of 1 x 10(4) CFU/ml of C. albicans. Seventy-two hours after the inoculation, caspofungin 100 microg/0.1 ml in group 1 (n = 6), voriconazole 50 microg/0.1 ml in group 2 (n = 6), amphotericin B 10 microg/0.1 ml in group 3 (n = 6), itraconazole 10 microg/0.1 ml in group 4 (n = 6), and 0.1 ml NaCl 0.9% in control group (n = 6) were injected into the vitreous cavity. Clinical and histopathologic examination scores and microbiological analysis of vitreous aspirates were compared.

RESULTS

There was statistically significant difference in the clinical scores, histopathologic scores, and mean CFU/ml between the treatment and control groups (p < 0.05). In caspofungin and voriconazole groups, histopathologic scores and mean CFU were lower than other treatment groups and control group.

CONCLUSIONS

Intravitreal injection of caspofungin and voriconazole was effective against C. albicans endophthalmitis in this experimental rabbit model.

Phenotypical characterization of Candida spp. isolated from crop of parrots (Amazona spp.)

The purpose of this study was to characterize Candida isolates from crop of parrots. Forty baby parrots of genus Amazona, species aestiva and amazonica that were apprehended from wild animal traffic were used: 18 presented ingluvitis and 22 other alterations, but showing general debilitation. Samples were seeded on Sabouraud dextrose agar with chloramphenicol after be obtained by the introduction of urethral probe through the esophagus. Based on morphology and biochemical reactions (API 20C) Candida was confirmed; it was still searched the production of proteinase and phospholipase, virulence factors for Candida species. Candida spp. were isolated from 57.5% parrots, being 72.2% from birds with ingluvitis and 45.5% from without ones. Twenty-five strains of Candida were isolated, 60% and 40%, respectively from parrots with and without ingluvitis, and were speciated: 28% C. humicola, 24% C. parapsilosis, 20% C. guilliermondii, 20% C. famata, and 8% C. albicans. These results demonstrate that C. albicans is not the most frequent species isolated, and it is the first report that shows C. guilliermondii, C. famata, and C. humicola causing infection in parrots. Many isolates presented filamentation (76%), 100% produced proteinase and 68% phospholipase. The observation of Candida spp. producing virulence factors reinforce the pathogenic role of these yeasts in the cases studied.

The epidemiology of Candida colonization and invasive candidiasis in a surgical intensive care unit where fluconazole prophylaxis is utilized: follow-up to a randomized clinical trial

OBJECTIVE

To determine whether Candida glabrata colonization and invasive candidiasis (IC) increased among critically ill surgical patients 3 years after the introduction of fluconazole prophylaxis to a surgical intensive care unit (SICU).

SUMMARY BACKGROUND DATA

Fluconazole prophylaxis has been shown in randomized clinical trials to reduce the occurrence of candidiasis in some patient populations, including high-risk SICU patients. One such trial was performed in The Johns Hopkins Hospital SICU in 1998. Whether the epidemiology of Candida colonization and IC has changed in SICUs where fluconazole prophylaxis is routinely utilized has not been adequately studied.

METHODS

We conducted a prospective, observational study of subjects admitted for > or = 3 days to the SICU of a large, urban, academic medical center, where fluconazole prophylaxis had been utilized for approximately 3 years. Surveillance fungal cultures of rectal/fecal swabs, urine, and endotracheal aspirates were performed on admission to the SICU, once weekly, and upon discharge from the SICU. Demographic and clinical data were collected. C. glabrata colonization and IC prevalence among patients in the prospective cohort were compared with the prevalence among SICU patients enrolled in the 1998 clinical trial of fluconazole for the prevention of candidiasis that was performed at the same institution.

RESULTS

C. glabrata colonization was not significantly more common among patients in the 2003 cohort as compared with patients in the 1998 trial (adjusted odds ratio [OR]: 0.90, 95% confidence interval [CI]: 0.57-1.41). Patients with IC in the 2003 cohort were not more likely than those in the 1998 trial to have IC due to C. glabrata (adjusted OR: 1.93, 95% CI: 0.20-18.98), while patients with IC in the 2003 cohort were less likely than patients in the 1998 trial to have acquired IC in the ICU (adjusted OR: 0.08, 95% CI: 0.009-0.82).

CONCLUSIONS

There was no increase in C. glabrata colonization or in the proportion of IC due to C. glabrata after a 3-year period of routine fluconazole prophylaxis for selected SICU patients.

Risk factors for fluconazole-resistant Candida glabrata bloodstream infections

BACKGROUND

Bloodstream infections (BSIs) caused by Candida glabrata have increased substantially. Candida glabrata is often associated with resistance to fluconazole therapy. However, to our knowledge, risk factors for fluconazole-resistant C glabrata BSIs have not been studied.

METHODS

A case-case-control study was conducted at 3 hospitals from January 1, 2003, to May 31, 2007. The 2 case groups included patients with fluconazole-resistant C glabrata BSIs (minimum inhibitory concentration > or =16 microg/mL) and patients with fluconazole-susceptible C glabrata BSIs (minimum inhibitory concentration < or =8 microg/mL). Hospitalized patients without C glabrata BSIs were randomly selected for inclusion in the control group and were frequency matched to cases on the basis of time at risk. Two case-control studies were performed using this shared control group. The primary risk factor of interest, previous fluconazole use, was evaluated at multivariate analyses, adjusting for demographic data, comorbid conditions, and antimicrobial exposures.

RESULTS

We included 76 patients with fluconazole-resistant C glabrata BSIs, 68 patients with fluconazole-susceptible C glabrata BSIs, and 512 control patients. Previous fluconazole use (adjusted odds ratio [95% confidence interval], 2.3 [1.3-4.2]) and linezolid use (4.6 [2.2-9.3]) were independent risk factors for fluconazole-resistant C glabrata BSIs; previous cefepime use (2.2 [1.2-3.9]) and metronidazole use (2.0 [1.1-3.5]) were independent risk factors for fluconazole-susceptible C glabrata BSIs.

CONCLUSIONS

Previous fluconazole use is a significant risk factor for health care-associated fluconazole-resistant C glabrata BSIs. Future studies will be needed to evaluate the effect of decreasing fluconazole use on rates of fluconazole-resistant C glabrata BSIs.

Evaluation of aminocandin and caspofungin against Candida glabrata including isolates with reduced caspofungin susceptibility

BACKGROUND

Aminocandin is an investigational echinocandin with excellent activity against Candida species, including Candida albicans and Candida tropicalis. However, few data are available for this agent versus Candida glabrata. We compared the in vitro potency and in vivo efficacy of aminocandin and caspofungin against clinical isolates of C. glabrata including those with reduced caspofungin susceptibility (MIC > 2 mg/L).

METHODS

In vitro activity was assessed using microdilution broth susceptibility testing. Three isolates, one with a low and two with elevated caspofungin MICs, were chosen and mice were infected with C. glabrata followed by a single dose of aminocandin or caspofungin (0.5-100 mg/kg), or daily doses of caspofungin (0.07-14.3 mg/kg) begun 1 day after inoculation. Reduction in fungal burden, assessed in kidney tissue on day 8 post-inoculation, was the marker of antifungal response.

RESULTS

Aminocandin was more potent than caspofungin against each isolate with reduced caspofungin susceptibility. Mice infected with the caspofungin-susceptible isolate had significant decreases in tissue burden with low doses of either drug. Higher single doses of aminocandin (> or = 10 mg/kg) were required to reduce fungal burden against the two isolates with elevated caspofungin MICs. Single dose administration of caspofungin was ineffective against one of these isolates, and higher daily doses were required to reduce fungal burden.

CONCLUSIONS

These studies suggest that aminocandin has the potential for extended interval dosing in the treatment of C. glabrata infections caused by susceptible isolates. However, higher doses may be required against isolates with reduced caspofungin susceptibility.

Risk factors for albicans and non-albicans candidemia in the intensive care unit

OBJECTIVE

To determine risk factors for bloodstream infections (BSI) with Candida non-albicans (C-NA) species and Candida albicans (CA) among critically ill patients.

DESIGN

Case-control study.

SETTING

Adult medical and surgical intensive care units (ICUs) at two university hospitals.

PATIENTS

Consecutive patients with C-NA and CA BSIs from 1995-2005 formed the two case groups. Controls were patients without candidemia who were randomly selected in a ratio of 5:1 and matched by study hospital, ICU type (medical vs. surgical) and by ICU admission date within a 3-month period.

INTERVENTIONS

Data collected included demographics, comorbidities, exposure to antibiotics and antifungals, and ICU factors such as total parenteral nutrition (TPN), blood product transfusions, invasive procedures, central venous catheters, hemodialysis, and mechanical ventilation. We built multivariable logistic regression models, which identified risk factors for C-NA or CA BSIs compared with controls. Variables were adjusted for time-at-risk.

MEASUREMENTS AND MAIN RESULTS

There were 67 patients with C-NA BSIs, 79 patients with CA BSIs, and 780 controls. In multivariable models, factors associated with an increased risk of C-NA compared with controls included major pre-ICU operations [odds ratio; (95% confidence interval)] [2.12; (1.14-3.97)], gastrointestinal procedures [2.24; (1.49-3.38)], enteric bacteremia [3.43; (1.39-8.48)], number of hemodialysis days [6.20; (2.67-14.4)], TPN duration [2.87; (1.40-5.90)], and mean number of red blood cell transfusions [2.72; (1.33-5.58)]. Factors associated with an increased risk of CA BSIs compared to controls were very similar and included major ICU operations [1.26; (1.14-3.97)], enteric bacteremia [3.45; (1.38-8.63)], number of hemodialysis days [3.84; (1.75-8.40)], TPN duration [11.0; (5.52-21.7)] and mean number of red blood cell transfusions [1.97; (0.98-3.99)].

CONCLUSIONS

We found multiple common risk factors for both non-C. albicans and C. albicans BSIs, however we could not differentiate between these two groups based on clinical characteristics alone.

Candida glabrata fungaemia in intensive care units

Candidaemia is increasingly important in intensive care units (ICUs). Compared with Candida albicans fungaemia, the impact of C. glabrata fungaemia on ICU patients is not well-known. The aim of this study was to investigate the clinical features, the antifungal susceptibility and the treatment outcomes of C. glabrata fungaemia in ICU patients. The medical records of ICU patients with candidaemia between 2000 and 2005 were reviewed retrospectively, and antifungal susceptibility testing was performed for isolates of C. glabrata. Among 147 episodes of candidaemia occurring in adult ICUs, C. glabrata was the second most common species and accounted for 45 (30%) episodes of candidaemia. The incidence of C. glabrata fungaemia was 1.3/1000 ICU admissions. Fluconazole resistance was found in 11% of C. glabrata isolates. The 30-day all-cause mortality rate was 58%. Therapeutic regimens containing amphotericin B were associated with better outcome. Despite higher fluconazole resistance, C. glabrata candidaemia was not associated with greater mortality than non-glabrata candidaemia in the ICU setting.

Hypercortisolemia and Infection

Hypercortisolemia is a condition involving a prolonged excess of serum levels of cortisol that can develop as a result of disregulatory abnormalities in the hypothalamic-pituitary-adrenal axis or from exogenous-source steroids. Hypercortisolemia induces a state of immunocompromise that predisposes the patient to various bacterial, viral, fungal, and parasitic infections. To ensure optimal management of hypercortisolemia, the primary clinician must be cognizant of its different causes and aware of the different infections associated with cortisol excess. In the hypercortisolemic patient, it is necessary to restore normal cortisol levels to reduce the risk of infection or to improve the control and cure of established infection.

The echinocandin micafungin: a review of the pharmacology, spectrum of activity, clinical efficacy and safety

Micafungin is a relatively broad-spectrum antifungal agent available for clinical use in the US and Japan. By inhibiting the production of beta-1,3-glucan, an essential fungal cell wall component, micafungin has reduced toxicity to mammalian cells while maintaining potent antifungal activity against many pathogenic fungi including polyene- and azole-resistant isolates. Indeed, micafungin has been shown to be efficacious in the treatment of infections caused by Candida and Aspergillus species in clinical trials without the associated toxicities of amphotericin B formulations and drug interactions that occur with the azoles. In this review, the pharmacology, spectrum of activity, clinical efficacy and safety profile of micafungin are discussed.

In vivo efficacy of anidulafungin and caspofungin against Candida glabrata and association with in vitro potency in the presence of sera

In vitro studies have demonstrated that anidulafungin has greater potency than caspofungin against Candida glabrata. However, data from in vivo studies demonstrating that it has superior efficacy are lacking. The objective of this study was to compare the activities of anidulafungin and caspofungin against C. glabrata in a murine model of disseminated candidiasis. Two clinical C. glabrata isolates were used, including one with reduced caspofungin susceptibility. MICs were determined by broth microdilution in the presence and absence of sera. For the animal studies, mice were immunosuppressed with 5-fluorouracil one day prior to intravenous inoculation. Treatment with anidulafungin and caspofungin (0, 0.5, 1, 5, and 10 mg/kg of body weight per day) was begun 24 h later and was continued through day 7 postinoculation. The CFU were enumerated from kidney tissue. According to the standard microdilution methodology, anidulafungin had superior in vitro activity. However, this enhanced potency was attenuated by the addition of mouse and human sera. Caspofungin reduced the kidney fungal burden at lower doses compared to that achieved with anidulafungin in mice infected with the isolate with the lower MIC. Against the strain with the elevated caspofungin MIC, both anidulafungin and caspofungin were effective in reducing the kidney fungal burden at the higher doses studied. Despite the greater in vitro activity of anidulafungin in the absence of sera, both echinocandins were similarly effective in reducing the fungal burden in kidney tissue. The superior in vitro activity of anidulafungin did not confer enhanced in vivo efficacy against C. glabrata.

Active surveillance for candidemia, Australia

This infection has a high death rate and is predominantly associated with healthcare.

Population-based surveillance for candidemia in Australia from 2001 to 2004 identified 1,095 cases. Annual overall and hospital-specific incidences were 1.81/100,000 and 0.21/1,000 separations (completed admissions), respectively. Predisposing factors included malignancy (32.1%), indwelling vascular catheters (72.6%), use of antimicrobial agents (77%), and surgery (37.1%). Of 919 episodes, 81.5% were inpatient healthcare associated (IHCA), 11.6% were outpatient healthcare associated (OHCA), and 6.9% were community acquired (CA). Concomitant illnesses and risk factors were similar in IHCA and OHCA candidemia. IHCA candidemia was associated with sepsis at diagnosis (p<0.001), death <30 days after infection (p<0.001), and prolonged hospital admission (p<0.001). Non–Candida albicans species (52.7%) caused 60.5% of cases acquired outside hospitals and 49.9% of IHCA candidemia (p = 0.02). The 30-day death rate was 27.7% in those >65 years of age. Adult critical care stay, sepsis syndrome, and corticosteroid therapy were associated with the greatest risk for death. Systematic epidemiologic studies that use standardized definitions for IHCA, OHCA, and CA candidemia are indicated.

Once-weekly micafungin therapy is as effective as daily therapy for disseminated candidiasis in mice with persistent neutropenia

The effect of micafungin dose scheduling on the treatment of candidemia is unknown. Neutropenic mice with disseminated Candida glabrata infection were treated with single intraperitoneal micafungin doses of 0 to 100 mg/kg of body weight and sacrificed 7 days later. The maximal decline in kidney fungal burden was 5.8 log(10) CFU/g. A 1-week pharmacokinetic-pharmacodynamic study revealed a micafungin serum half-life of 6.13 h. In mice treated with > or =50 mg/kg, there was maximal fungal decline without regrowth during the 1-week dosing interval. Next, doses associated with 34% (34% effective dose [ED(34)]) and 50% (ED(50)) of maximal kill were administered at one of three dose schedules: a single dose at t = 0, two equal doses at t = 0 and t = 3.5 days, and 7 equal doses daily. Some mice received a single dose of 100 mg/kg. Fungal burden was examined on days 1, 5, and 7. In mice treated with the ED(34), microbial kill with the daily therapy initially lagged behind the intermittent doses but exceeded it by day 7. In mice treated with the ED(50), daily and intermittent doses had equivalent day 7 effects. In mice treated with 100 mg/kg, there was no regrowth. The relative likelihoods that the area under the concentration-time curve/MIC ratio was linked to microbial kill versus peak concentration/MIC ratio or time above the MIC was 10.3 and 10,161.2, respectively. In all the experiments, no paradoxical increase in fungal burden was observed with high micafungin doses. However, only a single Candida isolate was tested. Regimens that simulated micafungin concentration-time profiles in patients treated with a single micafungin dose of 1,400 mg once a week demonstrated maximal fungal decline. Once-weekly micafungin therapy is as efficacious as daily therapy in a murine model of disseminated candidiasis.

Issues Related to the Design and Interpretation of Clinical Trials of Salvage Therapy for Invasive Mold Infection

Invasive mold infection is a major cause of morbidity and mortality among severely immunocompromised individuals. We discuss the challenges involved in the design and interpretation of salvage antifungal trials, focusing on mold infection. We suggest that patients with refractory fungal infection be analyzed separately from those with intolerance to standard regimens because of the poorer prognosis of the former group. We propose a composite outcome assessment in which refractory infection is defined as infection associated with the worsening of at least 2 of the following 3 types of criteria: clinical, radiologic, and mycologic. Confounding variables, including heterogeneity in host factors, initial antifungal therapy, and selection bias, are discussed. Although randomized studies would provide the most credible results, the lack of an adequate number of patients to meet prespecified stratification criteria for all confounding variables makes such studies impractical. Given that randomized studies are unrealistic, studies involving carefully selected, matched, contemporaneous control subjects are likely to be the most useful alternative.

Candidaemia in patients with haematological disorders and stem cell transplant

The incidence of non-albicans species of Candida has recently increased, especially in patients with malignant haematological disorders receiving fluconazole prophylaxis. A retrospective study of patients who developed candidaemia at Riyadh Armed Forces Hospital between January 1992 and December 2002 was carried out. Thirty one episodes of candidaemia occurred in 27 patients with a variety of haematological disorders. Twenty-four episodes were caused by non-albicans species of Candida and only 7 episodes were caused by C.albicans. The most frequent underlying haematological disorders were acute myeloid leukaemia (AML) followed by acute lymphoblastic leukaemia (ALL). The main predisposing factors for the development of candidaemia were: broad spectrum antibiotics, central venous catheters, neutropenia, cytotoxic chemotherapy, coexisting bacterial infections, steroid therapy, relapsing or untreated primary disease and fluconazole prophylaxis.

Eight episodes were complicated by chronic disseminated candidiasis. Amphotericin-B and amBisome were used in the treatment of Candida infections. The treatment was successful in 86% of the episodes of C. albicans and 50% of the episodes due to nonalbicans species of Candida. The highest mortality rate was encountered with C.tropicalis infections.

Candidaemia is an important cause of mortality and morbidity in patients with malignant haematological disorders and stem cell transplant. The predominance of non-albicans species of Candida especially C.krusei and C.tropicalis is alarming. The early administration of appropriate antifungal therapy and the removal of infected intravascular catheters improve the outcome considerably.

The emergence of non-albicans Candida species as causes of invasive candidiasis and candidemia

The last three decades have seen an expanding pool of high-risk patients susceptible to the opportunistic pathogen Candida. Accordingly, a dramatic increase in nosocomial blood stream infections (BSIs) due to Candida spp has been reported throughout the world, starting in tertiary care centers and spreading to community hospitals. This absolute increase in Candida BSIs was accompanied by both an absolute and then a proportional increase in invasive infection caused by reduced fluconazole-susceptible non-albicans Candida spp. Currently, the incidence trend of BSI has stabilized, and Candida albicans remains the most common species causing fungal BSI. Clinicians must be aware of the importance and implications of non-albicans Candida spp when selecting antifungal drugs, although most studies have not shown significant outcome differences with use of the various antifungal classes.