Breaking barriers in Candida spp. detection with Electronic Noses and artificial intelligence

The timely and accurate diagnosis of candidemia, a severe bloodstream infection caused by Candida spp., remains challenging in clinical practice. Blood culture, the current gold standard technique, suffers from lengthy turnaround times and limited sensitivity. To address these limitations, we propose a novel approach utilizing an Electronic Nose (E-nose) combined with Time Series-based classification techniques to analyze and identify Candida spp. rapidly, using culture species of C. albicans, C.kodamaea ohmeri, C. glabrara, C. haemulonii, C. parapsilosis and C. krusei as control samples. This innovative method not only enhances diagnostic accuracy and reduces decision time for healthcare professionals in selecting appropriate treatments but also offers the potential for expanded usage and cost reduction due to the E-nose's low production costs. Our proof-of-concept experimental results, carried out with culture samples, demonstrate promising outcomes, with the Inception Time classifier achieving an impressive average accuracy of 97.46% during the test phase. This paper presents a groundbreaking advancement in the field, empowering medical practitioners with an efficient and reliable tool for early and precise identification of candidemia, ultimately leading to improved patient outcomes.

Association of body mass index and bloodstream infections in patients on extracorporeal membrane oxygenation: a single-centre, retrospective, cohort study

BACKGROUND

Obesity is associated with poor clinical outcomes in critically ill patients. However, under some clinical conditions, obesity has protective effects. Bloodstream infections (BSI) are among the most common nosocomial infections associated with extracorporeal membrane oxygenation (ECMO). BSI during ECMO is associated with higher mortality rates and poorer clinical outcomes.

AIM

To analyse whether body mass index (BMI) is associated with BSI during ECMO or with in-hospital mortality.

METHODS

All adult patients who had received ECMO support for >48 h were included in the analysis. The analysis of total duration of ECMO support, in-hospital mortality and BSI was stratified by BMI category. The Cox proportional hazards model was used to compare the risk of BSI among BMI categories.

FINDINGS

In total, 473 patients were enrolled in the study. The average age was 56.5 years and 65.3% were men. The total duration of ECMO was approximately 11.8 days, with a mortality rate of 47.1%. The incidence rates of BSI and candidaemia were 20.5% and 5.5%, respectively. The underweight group required ECMO for respiratory support, whereas the overweight and obese groups required ECMO for cardiogenic support (P<0.0001). No significant difference in BSI rate was found (P=0.784). However, after adjusting for clinical factors, patients in Group 4 (BMI 25.0-<30.0 kg/m2) exhibited lower mortality compared with patients in Group 2 (normal BMI) (P=0.004).

CONCLUSION

BMI was not associated with risk of BSI, but patients with higher BMI showed lower in-hospital mortality associated with ECMO support.

[Anti-infective treatment of fungal infections by Candida and Aspergillus]

BACKGROUND

Invasive fungal infections caused by Candida or Aspergillus are associated with a high mortality. Knowledge about the risk factors, diagnosis and treatment management is crucial for improving the survival of those affected.

OBJECTIVE

To give a practical overview about risk factors and treatment management of Candida and Aspergillus infections as well as providing an outlook on new antifungal agents.

MATERIAL AND METHODS

Summary of the relevant literature and recommendations on candidemia and invasive candidiasis as well as invasive and chronic pulmonary aspergillosis.

RESULTS

The first line treatment of candidemia and invasive candidiasis are echinocandins including caspofungin, anidulafungin and micafungin. Regular blood cultures have to be taken to determine the duration of treatment. After the first negative control blood culture treatment should be continued for another 14 days. The first line treatment of invasive pulmonary aspergillosis is azoles including voriconazole and isavuconazole. The duration of treatment depends on disease severity and is recommended for 6-12 weeks. The duration of treatment for chronic pulmonary aspergillosis is 6-12 months. Therapeutic drug monitoring is recommended for voriconazole and for posaconazole. New antifungal agents including olorofim, fosmanogepix, opelconazole, rezafungin or ibrexafungerp will broaden the therapeutic spectrum in the foreseeable future.

CONCLUSION

Knowledge about risk factors and the correct treatment management is crucial for the survival of patients with invasive fungal infections.

The estimated burden of fungal diseases in Mali

Mali is a developing country facing several health challenges with a high rate of tuberculosis (TB) and a moderate HIV infection burden. Little is known or done about fungal diseases, yet they represent a significant public health problem in certain populations. The aim of this study was to estimate the national burden of fungal disease, and summarize data, diagnostic and treatment gaps. We used national demographics and PubMed searches to retrieve articles on published data on these infections and at-risk populations (pulmonary TB, HIV/AIDS patients, patients receiving critical care etc.) in Mali. The estimated Malian population was 21,251,000 in 2020 (UN), of which 45% were children <14 years. Among HIV patients, we estimate an annual incidence of 611 cryptococcosis, 1393 Pneumocystis pneumonia, 180 histoplasmosis and >5,700 esophageal candidiasis and some microsporidiosis cases. Our prevalence estimates for tinea capitis are 2.3 million, for recurrent vulvovaginal candidiasis 272,460, ∼60,000 fungal asthma and 7,290 cases of chronic pulmonary aspergillosis (often mistaken for TB). Less common acute fungal infections are probably invasive aspergillosis (n=1230), fungal keratitis (n=2820), candidaemia (>1,060) and mucormycosis (n=43). Histoplasmin was found in 6% in general population. A few cases of mycetoma are described in Mali. Many WHO Essential medicines and Diagnostics are not available in Mali. This shows a marked disparity in documented and estimated cases of fungal diseases in Mali. These infections are underestimated due to the lack of accurate diagnosis tools and lack of support for fungal diseases diagnosis and management.

The Role of Bacterial and Fungal Superinfection in Critical COVID-19

BACKGROUND

The range of reported rates of bacterial and fungal superinfections in patients with a severe course of COVID-19 is wide, suggesting a lack of standardised reporting.

METHODS

The rates of bacterial and fungal superinfection were assessed using predefined criteria to differentiate between infection and contamination.

RESULTS

Overall, 117 patients admitted to the Intensive Care Unit due to severe COVID-19 were included. Overall, 55% of patients developed a superinfection and 13.6% developed a fungal superinfection (5.9% candidemia and 7.7% CAPA). The rate of ventilator-associated pneumonia was 65.2%. If superinfection was detected, the length of hospital stay was significantly longer and the mortality was especially increased if candidemia was detected. An increased risk of superinfection was observed in patients with pre-existing diabetes mellitus or chronic heart failure. The presence of immunomodulating therapy did not seem to have an impact on the frequency of superinfections.

CONCLUSION

Increased awareness of high superinfection rates, fungal infections in particular, in patients suffering from severe COVID-19 is necessary.

Drimane Sesquiterpene Aldehydes Control Candida Yeast Isolated from Candidemia in Chilean Patients

Drimys winteri J.R. (Winteraceae) produce drimane sesquiterpenoids with activity against Candida yeast. In this work, drimenol, polygodial (1), isotadeonal (2), and a new drimane α,β-unsaturated 1,4-dialdehyde, named winterdial (4), were purified from barks of D. winteri. The oxidation of drimenol produced the monoaldehyde drimenal (3). These four aldehyde sesquiterpenoids were evaluated against six Candida species isolated from candidemia patients in Chilean hospitals. Results showed that 1 displays fungistatic activity against all yeasts (3.75 to 15.0 µg/mL), but irritant effects on eyes and skin, whereas its non-pungent epimer 2 has fungistatic and fungicide activities at 1.9 and 15.0 µg/mL, respectively. On the other hand, compounds 3 and 4 were less active. Molecular dynamics simulations suggested that compounds 1–4 are capable of binding to the catalytic pocket of lanosterol 14-alpha demethylase with similar binding free energies, thus suggesting a potential mechanism of action through the inhibition of ergosterol synthesis. According to our findings, compound 2 appears as a valuable molecular scaffold to pursue the future development of more potent drugs against candidiasis with fewer side effects than polygodial. These outcomes are significant to broaden the alternatives to treat fungal infections with increasing prevalence worldwide using natural compounds as a primary source for active compounds.

Transfusable neutrophil progenitors as cellular therapy for the prevention of invasive fungal infections

The use of mature neutrophil (granulocyte) transfusions for the treatment of neutropenic patients with invasive fungal infections (IFIs) has been the focus of multiple clinical trials. Despite these efforts, the transfusion of mature neutrophils has resulted in limited clinical benefit, likely owing to problems of insufficient numbers and the very short lifespan of these donor cells. In this report, we employed a system of conditionally immortalized murine neutrophil progenitors that are capable of continuous expansion, allowing for the generation of unlimited numbers of homogenous granulocyte-macrophage progenitors (GMPs). These GMPs were assayed in vivo to demonstrate their effect on survival in 2 models of IFI: candidemia and pulmonary aspergillosis. Mature neutrophils derived from GMPs executed all cardinal functions of neutrophils. Transfused GMPs homed to the bone marrow and spleen, where they completed normal differentiation to mature neutrophils. These neutrophils were capable of homing and extravasation in response to inflammatory stimuli using a sterile peritoneal challenge model. Furthermore, conditionally immortalized GMP transfusions significantly improved survival in models of candidemia and pulmonary aspergillosis. These data confirm the therapeutic benefit of prophylactic GMP transfusions in the setting of neutropenia and encourage development of progenitor cellular therapies for the management of fungal disease in high-risk patients.

Rapid detection of biofilm-producing Candida species via MALDI-TOF mass spectrometry

AIMS

The aim of this study was to evaluate the formation of biofilm by Candida spp. isolated from the bloodstream, using traditional spectrophotometric methodologies. In addition, the goal was to compare the results with those obtained through MALDI-TOF/MS, as well as to verify its use as a potential tool for the detection of biofilm-forming strains.

METHODS AND RESULTS

Hundred and thirteen isolates of Candida spp. were studied: 41 were Candida albicans, 27 C. tropicalis, 18 C. glabrata, 17 C. parapsilosis and 10 C. krusei. Metabolic activity was determined through the tetrazolium salt (XTT) reduction assay and biomass by staining with Crystal Violet. All isolates were able to form biofilm, 94% of which were strong producers, with high biomass quantification (95%; 107/113) and high metabolic activity (99%; 112/113). Mass spectra of the biofilm-producing isolates showed differences in the intensity of mass peaks when compared with the spectra of the nonproducing strains.

CONCLUSIONS

It was demonstrated that MALDI-TOF/MS was able to detect specific biofilm proteins, as the mass spectra of the isolates presented differences when compared with nonproducing strains.

SIGNIFICANCE AND IMPACT OF THE STUDY

MALDI-TOF/MS can become a valuable tool for biofilm detection at the moment of the identification of the microorganism, thus contributing greatly to the management of patients with Candidemia.

HIV Infection as Risk Factor for Death among Hospitalized Persons with Candidemia, South Africa, 2012-2017

HIV-seropositive persons demonstrated increased adjusted risk for 30-day mortality and should be evaluated for intensive care.

We determined the effect of HIV infection on deaths among persons >18 months of age with culture-confirmed candidemia at 29 sentinel hospitals in South Africa during 2012–2017. Of 1,040 case-patients with documented HIV status and in-hospital survival data, 426 (41%) were HIV-seropositive. The in-hospital case-fatality rate was 54% (228/426) for HIV-seropositive participants and 37% (230/614) for HIV-seronegative participants (crude odds ratio [OR] 1.92, 95% CI 1.50–2.47; p<0.001). After adjusting for relevant confounders (n = 907), mortality rates were 1.89 (95% CI 1.38–2.60) times higher among HIV-seropositive participants than HIV-seronegative participants (p<0.001). Compared with HIV-seronegative persons, the stratum-specific adjusted mortality OR was higher among HIV-seropositive persons not managed in intensive care units (OR 2.27, 95% CI 1.47–3.52; p<0.001) than among persons who were (OR 1.56, 95% CI 1.00–2.43; p = 0.05). Outcomes among HIV-seropositive persons with candidemia might be improved with intensive care.

[Establishment of mouse model and preliminary screening of serum biomarkers for Candidemia]

Objective: To establish mouse models of Candidemia, and investigates statistically significant polypeptide peaks to provide auxiliary diagnosis of this disease. Methods: A total of 170 specific pathogen free adult male ICR mice with body mass of 27-30 g were completely randomly divided into Candida albicans infection group (n=80), Candida parapsilosis infection group (n=80) and the normal control group (n=10), and the two kinds of Candidemia mouse models were established via tail vein injection. The serum samples were analyzed by Matrix-assisted laser desorption-ionization time of flight mass spectrometry and relevant software, and the polypeptide peaks with significant differences were screened to establish diagnostic models. Results: A total of 65 differential polypeptide peaks were obtained compared with the Candida albicans infection group and the normal control group. Combined with m/z 1 100.4, 1 581.0, 3 808.0 as differential polypeptide peaks to established the diagnostic model, the sensitivity was 95.24%(40/42), the specificity was 90.63%(29/32), the accuracy rate was 93.24%(69/74), and the AUC value of the ROC curve was 0.972(95%CI: 0.941-1.000). A total of 73 differential polypeptide peaks were obtained compared with Candida parapsilosis infection group and the normal control group. Combined with m/z 1 433.2, 1 148.5, 4 093.5, 4 522.2, 8 140.9, 8 234.6 as differential polypeptide peaks to established the diagnostic model, the sensitivity was 95%(38/40), the specificity was 81.25%(26/32), the accuracy rate was 88.89%(64/72), and the AUC value of the ROC curve was 0.953(95%CI: 0.903-1.000). A total of 78 differential polypeptide peaks were obtained compared with Candida albicans infection group and Candida parapsilosis infection group. Combined with m/z 2 736.9, 8 091.5, 8 153.7 as differential polypeptide peaks to established the diagnostic model, the accuracy of distinguishing C. albicans infection from C. parapsilosis infection was 98.78%(81/82). Conclusions: Successfully screened the differential polypeptides and established the related diagnostic models. Which is helpful to find serum biomarkers for the auxiliary diagnosis of Candidemia, and provides a basis for the early diagnosis and the rational use of drugs.

[Characterisation of Candida sp. isolated from patients after abdominal surgery]

INTRODUCTION

Intraabdominal candidiasis (IAC) is the predominant type of invasive candidiasis after candidemia. The majority of epidemiological studies on Candida are focused only on bloodstream infections. Nevertheless, the role of blood cultures has limited application in patients with abdominal candidiasis. IAC, which includes peritonitis and intraabdominal abscesses, may occur in around 40% of patients following repeat gastrointestinal (GI) surgery or GI perforation.

METHOD

Retrospective analysis of culture isolates of Candida sp. from clinical specimens of patients after abdominal surgery. The study period was from January 1 to October 31, 2016.

RESULTS

Our study of 33 patients with findings of Candida sp. from the abdominal cavity found a mortality of 15.2%, the most frequent strain being C. albicans and C. glabrata. All strains of Candida sp. were susceptible to echinocandins.

CONCLUSIONS

Candida sp. is part of normal microbiota of the gastrointestinal tract and its isolation is often difficult to interpret. Unfortunately, the pathophysiologic importance of Candida isolation from the abdominal space is not completely clear in many clinical situations.Key words: invasive candidiasis intra-abdominal candidiasis laboratory diagnostics.

Central venous catheter (CVC) removal for patients of all ages with candidaemia

BACKGROUND

Candida bloodstream infections most often affect those already suffering serious, potentially life-threatening conditions and often cause significant morbidity and mortality. Most affected persons have a central venous catheter (CVC) in place. The best CVC management in these cases has been widely debated in recent years, while the incidence of candidaemia has markedly increased.

OBJECTIVES

The main purpose of this review is to examine the impact of removing versus retaining a CVC on mortality in adults and children with candidaemia who have a CVC in place.

SEARCH METHODS

We searched the following databases from inception to 3 December 2015: Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE (Ovid SP), EMBASE (Ovid SP), the Commonwealth Agricultural Bureau (CAB), Web of Science and the Cumulative Index to Nursing and Allied Health Literature (CINAHL). We searched for missed, unreported and ongoing trials in trial registries and in reference lists of excluded articles.

SELECTION CRITERIA

We searched for randomized controlled trials (RCTs) and quasi-RCTs involving adults and children with candidaemia and in which participants were randomized for removal of a CVC (the intervention under study), irrespective of publication status, date of publication, blinding status, outcomes published or language.However, two major factors make the conduct of RCTs in this population a difficult task: the large sample size required to document the impact of catheter removal in terms of overall mortality; and lack of economic interest from the industry in conducting such a trial.

DATA COLLECTION AND ANALYSIS

Our primary outcome measure was mortality. Several secondary outcome measures such as required time for clearance of blood cultures for Candida species, frequency of persistent candidaemia, complications, duration of mechanical ventilation and length of stay in the intensive care unit (ICU) and in the hospital were planned, as were various subgroup and sensitivity analyses, according to our protocol. We assessed papers and abstracts for eligibility and resolved disagreements by discussion. However, we were not able to include any RCTs or quasi-RCTS in this review and, as a result, have carried out no meta-analyses. However, we have chosen to provide a brief overview of excluded observational studies.

MAIN RESULTS

We found no RCT and thus no available data for evaluation of the primary outcome (mortality) nor secondary outcomes or adverse effects. Therefore, we conducted no statistical analysis.A total of 73 observational studies reported on various clinically relevant outcomes following catheter removal or catheter retention. Most of these excluded, observational studies reported a beneficial effect of catheter removal in patients with candidaemia. None of the observational studies reported results in favour of retaining a catheter. However, the observational studies were very heterogeneous with regards to population, pathogens and interventions. Furthermore, they suffered from confounding by indication and an overall high risk of bias. As a consequence, we are not able to provide recommendations or to draw firm conclusions because of the difficulties involved in interpreting the results of these observational studies (very low quality of evidence, GRADE - Grades of Recommendation, Assessment, Development and Evaluation Working Group).

AUTHORS' CONCLUSIONS

Despite indications from observational studies in favour of early catheter removal, we found no eligible RCTs or quasi-RCTs to support these practices and therefore could draw no firm conclusions. At this stage, RCTs have provided no evidence to support the benefit of early or late catheter removal for survival or other important outcomes among patients with candidaemia; no evidence with regards to assessment of harm or benefit with prompt central venous catheter removal and subsequent re-insertion of new catheters to continue treatment; and no evidence on optimal timing of insertion of a new central venous catheter.

Risk factors for late recurrent candidaemia. A retrospective matched case-control study

Incidence, risk factors and clinical significance of late recurrent (LR) candidaemia (>1 month between episodes) remains unclear. The 1219 episodes of candidaemia detected from January 1985 to December 2014 were reviewed. We selected all cases with more than one episode separated by at least 30 days after clinical resolution in the interim (cases) and compared each of them with two controls (patients with single episodes of candidaemia). Clinical strains were genotyped to differentiate relapses from re-infection. Eighteen patients (1.48%) had 36 episodes of LR candidaemia (median 4 months). Independent risk factors for recurrence in the multivariate analysis were: underlying gastrointestinal disease (OR 67.16; 95% CI 5.23-861.71; p 0.001) and fungaemia due to Candida parapsilosis (OR 9.10; 95% 1.33-62.00; p 0.02). All episodes of LR candidaemia diagnosed during the first 3 months were due to an intravascular source of infection, whereas in those occurring after 3 months the main source of the disease was the abdomen, followed by endocarditis, and urinary tract. Molecular typing showed that 42.9% of LR candidaemias were relapses and 57.1% were re-infections. Neither time of recurrence nor clinical origin could predict type of recurrence. LR candidaemia is a relatively rare event that is more frequent in patients who have an initial episode of candidaemia due to C. parapsilosis or an underlying gastrointestinal disease. Episodes of LR candidaemia that occur within the first 3 months should prompt an attempt to exclude an intravascular source of infection, whereas those occurring later point to an intra-abdominal origin.

[Analysis of clinical characteristics in 122 adult patients with candidemia]

OBJECTIVE

To analyze the clinical characteristics of patients with candidemia for better clinical diagnosis and management of the disease.

METHOD

A retrospective study was carried out in 122 patients with confirmed diagnosis of candidemia from January 2010 to June 2014 in West China hospital of Sichuan University. The clinical features, risk factors, laboratory tests, treatments and clinical outcomes were reviewed and analyzed.

RESULTS

The clinical symptoms mainly include chill, shivering and fever (moderate fever or high fever). A total of 85 patients (69.7%) complicated with more than or equal to two kinds of underlying diseases, and 108 patients (88.5%) have more than or equal to three risk factors.There were 82.8% patients with increased white blood cell counts, 49.2% patients with elevated aminotransferase levels and 41.0% patients with increased creatinine levels. The isolated strains were albicans (42, 34.6%), tropicalis (32, 26.2%), glabrata (23, 18.9%) and parapsilosis (18, 14.8%). Susceptibility tests indicated some strains were resistant to antifungal drugs. Sixty-seven patients were cured or improved, 55 died or discharged voluntarily. The mortality rate was 45.1%. The multivariate Logistic regression analysis showed the independent correlative factors of mortality were mechanical ventilation (OR=4.9, P=0.02), malignancy (OR=11.39, P=0.01) and diabetes (OR=5.93, P=0.02). Early empiric anti-fungal therapy helped reduce the fatality rate (OR=0.12, P=0.03).

CONCLUSION

Actively treating underlying diseases can improve the clinical effect. The key to decrease the mortality is appropriate antifungal chemotherapy.

[Clinical characteristics and influencing factors of nosocomial candidemia]

OBJECTIVE

To retrospectively explore the clinical features and risk factors of nosocomially acquired candidemia.

METHODS

Retrospective analyses were conducted for general information, underlying diseases, risk factors, clinical features and laboratory tests of blood culture Candida-positive cases at Beijing Hospital from January 1, 2006 to December 31, 2011. Comparisons were made with regards to the clinical features, prognostic factors, risk factors of candidemia pathogen distribution between dead and survival groups and Candida albicans vs non-Candida albicans groups. Statistical analysis was performed with SPSS 19.0.

RESULTS

A total of 30 Candida albicans and 35 non-candida albicans cases were recruited. Their mean age was (76±14) years and total in-hospital fatality rate 58.5% (38/65). The acute physiology and chronic health evaluation II (APACHE II) score, ratio of APACHE II score>24 points, ratio of shock, primary diagnosis time (from onset to reporting time of positive outcome of blood culture) and ratio of serum albumin≤30 g/L of death group were (28.7±8.6) score, 55.3% (21/38), 71.1% (27/38), (138.7±50.4) h, 47.4% (18/38) respectively. And the values were significantly higher than those of survival group, i.e. (20.1±8.0) score, 29.6% (8/27), 44.4% (12/27), (127.2±50.2) h and 22.2% (6/27) respectively. Multivariate Logistic regression analysis showed that shock (OR=4.821, P=0.030), primary diagnosis time (OR=1.594, P=0.027) and APACHE II score (OR=1.096, P=0.032) were independent risk factors for death. However continuous blood purification therapy was an independent protective factor (OR=0.014, P=0.004). And diabetes was an independent risk factors for non-Candida albicans infection (OR=4.426, P=0.016).

CONCLUSIONS

Advanced age, more underlying diseases, severe clinical conditions and high fatality rate are the major clinical characteristics of candidemia. Shock, APACHE II score and primary diagnosis time are independent risk factors for death. Continuous blood purification therapy is a protective factor. And diabetes is an independent risk factor for non-Candida albicans candidemia.