[Towards an early diagnosis of invasive candidiasis in the critically ill patient]

Anti-Candida Antibodies of Patients with Invasive Candidiasis Inhibit Growth, Alter Cell Wall Structure, and Kill Candida albicans In Vitro

Invasive candidiasis (IC), caused by Candida yeasts, particularly Candida albicans, poses a significant threat with high mortality rates. Diagnosis is challenging due to Candida's common presence in human microbiota. To address this, our research group developed an immunofluorescence assay detecting Candida albicans Germ Tube Antibodies (CAGTA) in IC patients. CAGTA, indicative of invasive processes, is associated with a lower mortality rate in ICU patients. Based on this premise, this study aims to provide results regarding the lack of knowledge about the potential activity of CAGTA against invasive infections in humans caused by the fungus Candida albicans. Therefore, in order to characterize the activity of CAGTA produced by patients with IC, we used sera from 29 patients with IC caused by either C. albicans or non-albicans Candida species. Whole serum IgG antibodies were fractionated into anti-blastospores, CAGTA-enriched, and purified CAGTA and the assessments included XTT colorimetric assays for metabolic activity, CFU counts for viability, and microscopy for growth, viability, and morphological analysis. The CAGTA-enriched IgG fraction significantly reduced the metabolic activity and viability of C. albicans compared to anti-blastospores. Purified CAGTA altered germ tube cell wall surfaces, as revealed by electron microscopy, and exhibited fungicidal properties by DiBAC fluorescent staining. In conclusion, antibodies in response to invasive candidiasis have antifungal activity against Candida albicans, influencing metabolic activity, viability, and cell wall structure, leading to cell death. These findings suggest the potential utility of CAGTA as diagnostic markers and support the possibility of developing immunization protocols against Candida infections.

Study of Candidemia and its Antifungal Susceptibility Profile at the University Hospital of Montevideo, Uruguay

Systemic candidiasis are high mortality infections caused by yeasts of the genus Candida, affecting patients with numerous risk factors. Nowadays, candidemia produced by "non-albicans" species has increased considerably. Timely diagnosis and subsequent treatment substantially improve patients' survival. Our objectives are to study the frequency, distribution, and antifungal susceptibility profiles of candidemia isolates in our hospital. We conducted a descriptive, cross-sectional study. Positive blood cultures were recorded from January 2018 to December 2021. Positive Candida genus blood cultures were selected, classified, and analyzed on their susceptibility profile for amphotericin B, fluconazole and caspofungin using AST-YS08® card for VITEK 2 Compact® to determine minimum inhibitory concentration (MIC) and CLSI M60 2020 2nd Edition to determine breakpoints. 3862 positive blood cultures were obtained, 113 (2.93%) presented growth of Candida spp., corresponding to 58 patients. 55.2% came from the Hospitalization Ward and Emergency Services and 44.8% from the Intensive Care Unit. The species were distributed as follows: Nakaseomyces glabratus (Candida glabrata) (32.74%), Candida albicans (27.43%), Candida parapsilosis (23.01%), Candida tropicalis (7.08%) and others (9.73%). Most species were found to be susceptible to most antifungals, except for C. parapsilosis, presenting 4 isolates with resistance to fluconazole and N. glabratus (C. glabrata), whose clinical susceptibility data remains insufficient to provide accurate breakpoints. The percentage of recorded positive blood cultures of Candida spp. was 2.93%, these results were consistent with those reported at a regional level. A predominance of "non-albicans" species was observed. It is essential to know the prevalence, epidemiology, and susceptibility profiles of candidemia in our country, as well as being updated on its subsequent changes, maintaining epidemiological surveillance. This allows professionals to map out early and effective therapeutic strategies, staying alert of possible multi-resistant strains.

Effect of Cinnamomum verum leaf essential oil on virulence factors of Candida species and determination of the in-vivo toxicity with Galleria mellonella model

BACKGROUND

Essential oils (EO) extracted from Cinnamomum verum has been used as an antimicrobial agents for centuries. The effects of C. verum leaf oil against virulence of microorganisms is not well studied yet.

OBJECTIVES

This study evaluates the effect of C. verum leaf oil against three virulence factors of Candida albicans, C. tropicalis and C. dubliniensis and its in-vivo toxicity.

METHODS

Chemical composition of EO was determined using gas chromatography-mass spectrometry (GC-MS). Minimum inhibitory concentration (MIC) was determined using clinical and laboratory standards institute (CLSI) M27-A3 broth microdilution. Effect of EO on initial adhesion was quantified using XTT assay after allowing Candida cells to adhere to the polystyrene surface for 2 h. Biofilm formation of Candida in the presence of EO was quantified using XTT viability assay. Efficacy on reduction of germ tube formation was evaluated using standard protocol. Visualisation of biofilm formation and progression under the EO treatment were done using scanning electron microscope (SEM) and Time lapses microscope respectively. In-vivo toxicity of EO was determined using Galleria mellonella larvae. Chlorhexidine digluconate: positive control.

RESULTS

Eugenol was the main compound of EO. MIC was 1.0 mg/mL. 50% reduction in initial adhesion was achieved by C. albicans, C. tropicalis and C. dubliniensis with 1.0, > 2.0 and 0.34 mg/mL respectively. 0.5 and 1.0 mg/mL significantly inhibit the germ tube formation. MBIC50 for forming biofilms were ≤ 0.35 mg/mL. 1.0 mg/mL prevent biofilm progression of Candida. SEM images exhibited cell wall damages, cellular shrinkages and decreased hyphal formation. No lethal effect was noted with in-vivo experiment model at any concentration tested.

CONCLUSION

C. verum leaf oil acts against virulence factors of Candida and does not show any toxicity.

Anti-Candidaalbicans germ tube antibodies reduce in vitro growth and biofilm formation of C. albicans

BACKGROUND

Invasive candidiasis by Candida albicans is associated with high morbidity and mortality, due in part to the late implementation of an appropriate antifungal therapy hindered by the lack of an early diagnosis.

AIMS

We aimed to evaluate the in vitro antifungal activity of the antibodies against C. albicans germ tubes (CAGTA) raised in a rabbit model of candidemia.

METHODS

We measured the effect of CAGTA activity by colorimetric XTT and crystal violet assays, and colony forming units count, both on C. albicans planktonic cells and during the course of biofilm formation and maturation. Viability and cell morphology were assessed by optical, fluorescent or scanning electron microscopy.

RESULTS

CAGTA ≥50μg/ml caused a strong inhibition of C. albicans blastospores growth, and DiBAC fluorescent staining evidenced a fungicidal activity. Moreover, electron microscopy images revealed that CAGTA induced morphological alterations of the surface of C. albicans germ tubes grown free as well as in biofilm. Interestingly, CAGTA ≥80μg/ml reduced the amount of C. albicans biofilm, and this effect started at the initial adhesion stage of the biofilm formation, during the first 90min.

CONCLUSIONS

This is the first report showing that CAGTA reduce C. albicans growth, and impair its metabolic activity and ability to form biofilm in vitro. The antigens recognized by CAGTA could be the basis for the development of immunization protocols that might protect against Candida infections.

Immunoproteomic Analysis of Antibody Responses to Extracellular Proteins of Candida albicans Revealing the Importance of Glycosylation for Antigen Recognition

During infection, the human pathogenic fungus Candida albicans undergoes a yeast-to-hypha transition, secretes numerous proteins for invasion of host tissues, and modulates the host's immune response. Little is known about the interplay of C. albicans secreted proteins and the host adaptive immune system. Here, we applied a combined 2D gel- and LC-MS/MS-based approach for the characterization of C. albicans extracellular proteins during the yeast-to-hypha transition, which led to a comprehensive C. albicans secretome map. The serological responses to C. albicans extracellular proteins were investigated by a 2D-immunoblotting approach combined with MS for protein identification. On the basis of the screening of sera from candidemia and three groups of noncandidemia patients, a core set of 19 immunodominant antibodies against secreted proteins of C. albicans was identified, seven of which represent potential diagnostic markers for candidemia (Xog1, Lip4, Asc1, Met6, Tsa1, Tpi1, and Prx1). Intriguingly, some secreted, strongly glycosylated protein antigens showed high cross-reactivity with sera from noncandidemia control groups. Enzymatic deglycosylation of proteins secreted from hyphae significantly impaired sera antibody recognition. Furthermore, deglycosylation of the recombinantly produced, secreted aspartyl protease Sap6 confirmed a significant contribution of glycan epitopes to the recognition of Sap6 by antibodies in patient's sera.

[Update on invasive candidiasis in non-neutropenic critically ill adult patients]

Invasive candidiasis in non-neutropenic critically ill patients remains a challenge for clinicians due to its association with high morbidity and mortality rates, increased incidence, and health-care costs. It is well known that early diagnosis and treatment are associated with a better prognosis. For these reasons a thorough update has been performed in this setting focused on recent Spanish epidemiology, new predictive scores and microbiological tests such as mannan antigen, mannan antibodies, Candida albicans germ-tube antibodies or (1→3)-β-D-glucan detection, molecular techniques for the detection of fungal-specific DNA, advances in antifungal treatment and educational programs in Spain. An early diagnostic and therapeutic algorithm is proposed based on the combination of scores and microbiological test. The aim of this review is to provide physicians with the best information available in order to improve the prognosis of these patients.

Cost-effectiveness of three echinocandins and fluconazole in the treatment of candidemia and/or invasive candidiasis in nonneutropenic adult patients

OBJECTIVE

To estimate the cost-effectiveness of three echinocandins (anidulafungin, caspofungin, and micafungin) and generic fluconazole in the treatment of nonneutropenic adult patients with candidemia and/or invasive candidiasis in intensive care units in Spain.

MATERIALS AND METHODS

A decision-tree model was applied. The success and safety (hepatic and renal adverse effects) of first-line treatments were obtained from meta-analyses and systematic reviews of clinical trials. In the case of failure, a second-line treatment (liposomal amphotericin B after the echinocandins, or one of the echinocandins after fluconazole) was administered. The duration of the treatments (14 days total) was established by a panel of clinical experts using the Delphi method and according to Infectious Diseases Society of America guidelines. The cost of the medications and renal toxicity were considered. Deterministic and probabilistic sensitivity analysis using Monte Carlo simulations were carried out.

RESULTS

The total cost of the treatment of candidemia and/or invasive candidiasis with anidulafungin, caspofungin, micafungin, and fluconazole was €5,483, €5,968, €6,231, and €2,088, respectively. Anidulafungin was the dominant treatment (more effective, less expensive) compared to micafungin and caspofungin. The cost of achieving one more patient successfully treated with anidulafungin, caspofungin, and micafungin compared to fluconazole was €17,199, €23,962, and €27,339, respectively. The result remained stable, despite modification of the duration of the first-line and second-line treatments, as well as most of the dosing regimens. The probabilistic analysis also remained stable.

CONCLUSION

In accordance with this economic study, anidulafungin would produce savings and would be the dominant treatment compared with micafungin and caspofungin in nonneutropenic adult patients with candidemia and/or invasive candidiasis in intensive care units in Spain.

ÉPICO project. Development of educational recommendations using the DELPHI technique on invasive candidiasis in non-neutropenic critically ill adult patients

BACKGROUND

Although there has been an improved management of invasive candidiasis in the last decade, controversial issues still remain, especially in the diagnostic and therapeutic approaches.

AIMS

We sought to identify the core clinical knowledge and to achieve high level agreement recommendations required to care for critically ill adult patients with invasive candidiasis.

METHODS

A prospective Spanish survey reaching consensus by the DELPHI technique was made. It was anonymously conducted by electronic mail in a first term to 25 national multidisciplinary experts in invasive fungal infections from five national scientific societies, including intensivists, anesthesiologists, microbiologists, pharmacologists and infectious diseases specialists, who answered to 47 questions prepared by a coordination group after a strict review of the literature in the last five years. The educational objectives spanned five categories, including epidemiology, diagnostic tools, prediction rules, and treatment and de-escalation approaches. The level of agreement achieved among the panel experts in each item should exceed 75% to be selected. In a second term, after extracting recommendations from the selected items, a face to face meeting was performed where more than 80 specialists in a second round were invited to validate the preselected recommendations.

RESULTS

In the first term, 20 recommendations were preselected (Epidemiology 4, Scores 3, Diagnostic tools 4, Treatment 6 and De-escalation approaches 3). After the second round, the following 12 were validated: (1) Epidemiology (2 recommendations): think about candidiasis in your Intensive Care Unit (ICU) and do not forget that non-Candida albicans-Candida species also exist. (2) Diagnostic tools (4 recommendations): blood cultures should be performed under suspicion every 2-3 days and, if positive, every 3 days until obtaining the first negative result. Obtain sterile fluid and tissue, if possible (direct examination of the sample is important). Use non-culture based methods as microbiological tools, whenever possible. Determination of antifungal susceptibility is mandatory. (3) Scores (1 recommendation): as screening tool, use the Candida Score and determine multicolonization in high risk patients. (4) Treatment (4 recommendations): start early. Choose echinocandins. Withdraw any central venous catheter. Fundoscopy is needed. (5) De-escalation (1 recommendation): only applied when knowing susceptibility determinations and after 3 days of clinical stability. The higher rate of agreement was achieved in the optimization of microbiological tools and the withdrawal of the catheter, whereas the lower rate corresponded to de-escalation therapy and the use of scores.

CONCLUSIONS

The management of invasive candidiasis in ICU patients requires the application of a broad range of knowledge and skills that we summarize in our recommendations. These recommendations may help to identify the potential patients, standardize their global management and improve their outcomes, based on the DELPHI methodology.

Combined use of nonculture-based lab techniques in the diagnosis and management of critically ill patients with invasive fungal infections

Invasive fungal infections are associated with high morbidity and mortality in critically ill patients due, in part, to diagnostic difficulties in the early stages. Nonculture-based techniques such as (1,3)-β-d-glucan, galactomannan, mannan and antimannan antibodies, Candida albicans germ tube-specific antibodies or fungal DNA are required for earlier diagnosis, prognostic information and monitoring outcome. A decision-tree algorithm based on the combination of nonculture-based techniques is suggested to optimize the diagnosis and evolution of critically ill patients at risk of invasive mycoses. The use of (1,3)-β-d-glucan and blood cultures twice a week is proposed; if positive, treatment initiation is recommended alongside the performance of the nonculture-based microbiological tool depending on suspected mycoses and the availability of techniques.

[Épico project: Development of educational recommendations using the DELPHI technique on invasive candidiasis in non-neutropenic critically ill adult patients. Grupo Proyecto Épico]

BACKGROUND

Although there has been an improved management of invasive candidiasis in the last decade, controversial issues still remain, especially in the diagnostic and therapeutic approaches.

AIMS

We sought to identify the core clinical knowledge and to achieve high level agreement recommendations required to care for critically ill adult patients with invasive candidiasis.

METHODS

A prospective Spanish survey reaching consensus by the DELPHI technique was made. It was anonymously conducted by electronic mail in a first term to 25 national multidisciplinary experts in invasive fungal infections from five national scientific societies, including intensivists, anesthesiologists, microbiologists, pharmacologists and infectious diseases specialists, who answered to 47 questions prepared by a coordination group after a strict review of the literature in the last five years. The educational objectives spanned five categories, including epidemiology, diagnostic tools, prediction rules, and treatment and de-escalation approaches. The level of agreement achieved among the panel experts in each item should exceed 75% to be selected. In a second term, after extracting recommendations from the selected items, a face to face meeting was performed where more than 80 specialists in a second round were invited to validate the preselected recommendations.

RESULTS

In the first term, 20 recommendations were preselected (Epidemiology 4, Scores 3, Diagnostic tools 4, Treatment 6 and De-escalation approaches 3). After the second round, the following 12 were validated: (1) Epidemiology (2 recommendations): think about candidiasis in your Intensive Care Unit (ICU) and do not forget that non-Candida albicans-Candida species also exist. (2) Diagnostic tools (4 recommendations): blood cultures should be performed under suspicion every 2-3 days and, if positive, every 3 days until obtaining the first negative result. Obtain sterile fluid and tissue, if possible (direct examination of the sample is important). Use non-culture based methods as microbiological tools, whenever possible. Determination of antifungal susceptibility is mandatory. (3) Scores (1 recommendation): as screening tool, use the Candida Score and determine multicolonization in high risk patients. (4) Treatment (4 recommendations): start early. Choose echinocandins. Withdraw any central venous catheter. Fundoscopy is needed. (5) De-escalation (1 recommendation): only applied when knowing susceptibility determinations and after 3 days of clinical stability. The higher rate of agreement was achieved in the optimization of microbiological tools and the withdrawal of the catheter, whereas the lower rate corresponded to de-escalation therapy and the use of scores.

CONCLUSIONS

The management of invasive candidiasis in ICU patients requires the application of a broad range of knowledge and skills that we summarize in our recommendations. These recommendations may help to identify the potential patients, standardize their global management and improve their outcomes, based on the DELPHI methodology.

Épico Project. Development of educational recommendations using the DELPHI technique on invasive candidiasis in non-neutropenic critically ill adult patients

BACKGROUND

Although there has been an improved management of invasive candidiasis in the last decade, controversial issues still remain, especially in the diagnostic and therapeutic approaches.

AIMS

We sought to identify the core clinical knowledge and to achieve high level agreement recommendations required to care for critically ill adult patients with invasive candidiasis.

METHODS

A prospective Spanish survey reaching consensus by the DELPHI technique was made. It was anonymously conducted by electronic mail in a first term to 25 national multidisciplinary experts in invasive fungal infections from five national scientific societies, including intensivists, anesthesiologists, microbiologists, pharmacologists and infectious diseases specialists, who answered to 47 questions prepared by a coordination group after a strict review of the literature in the last five years. The educational objectives spanned five categories, including epidemiology, diagnostic tools, prediction rules, and treatment and de-escalation approaches. The level of agreement achieved among the panel experts in each item should exceed 75% to be selected. In a second term, after extracting recommendations from the selected items, a face to face meeting was performed where more than 80 specialists in a second round were invited to validate the preselected recommendations.

RESULTS

In the first term, 20 recommendations were preselected (Epidemiology 4, Scores 3, Diagnostic tools 4, Treatment 6 and De-escalation approaches 3). After the second round, the following 12 were validated: (1) Epidemiology (2 recommendations): think about candidiasis in your Intensive Care Unit (ICU) and do not forget that non-Candida albicans-Candida species also exist. (2) Diagnostic tools (4 recommendations): blood cultures should be performed under suspicion every 2-3 days and, if positive, every 3 days until obtaining the first negative result. Obtain sterile fluid and tissue, if possible (direct examination of the sample is important). Use non-culture based methods as microbiological tools, whenever possible. Determination of antifungal susceptibility is mandatory. (3) Scores (1 recommendation): as screening tool, use the Candida Score and determine multicolonization in high risk patients. (4) Treatment (4 recommendations): start early. Choose echinocandins. Withdraw any central venous catheter. Fundoscopy is needed. (5) De-escalation (1 recommendation): only applied when knowing susceptibility determinations and after 3 days of clinical stability. The higher rate of agreement was achieved in the optimization of microbiological tools and the withdrawal of the catheter, whereas the lower rate corresponded to de-escalation therapy and the use of scores.

CONCLUSIONS

The management of invasive candidiasis in ICU patients requires the application of a broad range of knowledge and skills that we summarize in our recommendations. These recommendations may help to identify the potential patients, standardize their global management and improve their outcomes, based on the DELPHI methodology.