Genotypic and phenotypic characteristics of Candida parapsilosis bloodstream isolates: Health Care Associated Infections in a teaching Hospital in Italy

BACKGROUND

Candidemia is the most common healthcare associated invasive fungal infection. Over the last few decades, candidemia caused by Candida species other than Candida albicans, particularly the Candida parapsilosis complex, has emerged worldwide. The aims of this study were: to analyze the genotypic and phenotypic characteristics of C. parapsilosis strains isolated from blood cultures and the environment in a hospital in southern Italy, to study the possible source of infection and to correlate the isolated strains.

METHODS

From April to October 2022, cases of candidemia due to C. parapsilosis in patients admitted to a hospital in the Apulia region were investigated. However, 119 environmental samples from the intensive care unit were collected for identification of the likely environmental reservoir of infection. Routine antifungal (amphotericin B, anidulafungin, fluconazole) susceptibility was performed on all isolates. Whole genome sequencing was performed to study the genotypic correlation of the isolates. Biofilm biomass and metabolic activity were also quantified for all isolates.

RESULTS

A total of 43 C. parapsilosis isolates were cultured from the bloodstream of each patient in different departments, and seven surface samples were positive for C. parapsilosis. Most of the isolated yeasts (41/50; 85 %) were resistant to fluconazole and were genetically related to each other, suggesting an ongoing clonal outbreak of this pathogen. The fluconazole-susceptible isolates produced significantly more biofilm than did the resistant isolates. Metabolic activity was also higher for fluconazole-susceptible than resistant isolates.

CONCLUSION

Cross-transmission of the microorganisms is suggested by the phenotypic similarity and genetic correlation between clinical and environmental strains observed in our study.

The efficacy of fluconazole for anti-fungal prophylaxis in peritoneal dialysis patients: A systematic review and meta-analysis

INTRODUCTION AND OBJECTIVES

The efficacy of fluconazole as a prophylactic strategy in patients with chronic kidney disease (CKD) on peritoneal dialysis (PD) with prior antibiotic exposure is controversial in the current literature. This study aimed to compare a strategy of fluconazole prophylaxis versus no-prophylaxis for patients in PD on antibiotics for previous episodes of peritonitis.

MATERIALS AND METHODS

We performed a systematic review and meta-analysis of observational studies and randomized controlled trials (RCTs) comparing fluconazole prophylaxis with no prophylaxis for PD-related peritonitis. The search was conducted on PubMed, EMBASE, and Cochrane Central in January 23, 2023. The outcome of interest was the occurrence of fungal peritonitis (FP).

RESULTS

We included six studies (1 RCT, 5 observational) with 4515 occurrences of peritonitis, of which 1098 (24.8%) received fluconazole prophylaxis in variable doses, whereas 3417 (75.6%) did not receive prophylaxis during peritonitis episodes. Overall, fluconazole prophylaxis was associated with a lower incidence of FP (OR 0.22; 95% CI 0.12-0.41; p<0.001; I2=0%). Subgroup analysis of studies that administered daily doses of fluconazole also demonstrated a reduced incidence of FP in patients who received antifungal prophylaxis (OR 0.31; CI 0.14-0.69; p=0.004; I2=0%).

CONCLUSIONS

In this meta-analysis of 4515 episodes of PD-related peritonitis, prophylaxis with fluconazole significantly reduced episodes of FP as compared with no antifungal prophylaxis.

Bisifusarium dimerum species complex central line-associated bloodstream infection in an immunocompetent patient

Albeit invasive fusariosis is extremely rare in immunocompetent patients, we describe an immunocompetent patient suffering from a central line-associated blood stream infection (CLABSI) and the difficulties in distinguishing between blood culture contamination and clinical significance.

Predictors and outcomes of peritoneal dialysis-related infections due to filamentous molds (MycoPDICS)

Introduction

We sought to evaluate the predictors and outcomes of mold peritonitis in patients with peritoneal dialysis (PD).

Methods

This cohort study included PD patients from the MycoPDICS database who had fungal peritonitis between July 2015-June 2020. Patient outcomes were analyzed by Kaplan Meier curves and the Log-rank test. Multivariable Cox proportional hazards model regression was used to estimating associations between fungal types and patients’ outcomes.

Results

The study included 304 fungal peritonitis episodes (yeasts n = 129, hyaline molds n = 122, non-hyaline molds n = 44, and mixed fungi n = 9) in 303 patients. Fungal infections were common during the wet season (p <0.001). Mold peritonitis was significantly more frequent in patients with higher hemoglobin levels, presentations with catheter problems, and positive galactomannan (a fungal cell wall component) tests. Patient survival rates were lowest for non-hyaline mold peritonitis. A higher hazard of death was significantly associated with leaving the catheter in-situ (adjusted hazard ratio [HR] = 6.15, 95%confidence interval [CI]: 2.86–13.23) or delaying catheter removal after the diagnosis of fungal peritonitis (HR = 1.56, 95%CI: 1.00–2.44), as well as not receiving antifungal treatment (HR = 2.23, 95%CI: 1.25–4.01) or receiving it for less than 2 weeks (HR = 2.13, 95%CI: 1.33–3.43). Each additional day of antifungal therapy beyond the minimum 14-day duration was associated with a 2% lower risk of death (HR = 0.98, 95%CI: 0.95–0.999).

Conclusion

Non-hyaline-mold peritonitis had worse survival. Longer duration and higher daily dosage of antifungal treatment were associated with better survival. Deviations from the 2016 ISPD Peritonitis Guideline recommendations concerning treatment duration and catheter removal timing were independently associated with higher mortality.

Where the infection is isolated rather than the specific species correlates with adherence strength, whereas biofilm density remains static in clinically isolated Candida and arthroconidial yeasts

To colonize and infect the host, arthroconidial yeasts must avoid being killed by the host's defenses. The formation of biofilms on implanted devices allows fungi to avoid host responses and to disseminate into the host. To better study the mechanisms of infection by arthroconidial yeasts, adherence and biofilm formation were assayed using patient samples collected over 10 years. In clinical samples, adherence varies within species, but the relative adherence is constant for those samples isolated from the same infection site. Herein we document, for the first time, in-vitro biofilm formation by Trichosporon dohaense, T. ovoides, T. japonicum, T. coremiiforme, Cutaneotrichosporon mucoides, Cutaneotrichosporon cutaneum, Galactomyces candidus, and Magnusiomyces capitatus on clinically relevant catheter material. Analysis of biofilm biomass assays indicated that biofilm mass changes less than 2-fold, regardless of the species. Our results support the hypothesis that most pathogenic fungi can form biofilms, and that biofilm formation is a source of systemic infections.

Fusarium: The versatile pathogen

Fusarium is an emerging human opportunistic pathogen of growing importance, especially among immunosuppressed haematology patients due to an increased incidence of disseminated infections over the past two decades. This trend is expected only to continue due to the advances in medical and surgical technologies that will prolong the lives of the severely ill, making these patients susceptible to rare opportunistic infections. Production of mycotoxins, enzymes such as proteases, angio-invasive property and an intrinsically resistant nature, makes this genus very difficult to treat. Fusarium is frequently isolated from the cornea and less commonly from nail, skin, blood, tissue, Continuous Ambulatory Peritoneal Dialysis (CAPD) fluid, urine and pleural fluid. Conventional microscopy establishes the genus, but accurate speciation requires multilocus sequence typing with housekeeping genes such as internal transcribed spacer, translation elongation factor-1α and RPB1 and 2 (largest and second largest subunits of RNA polymerase), for which expansive internet databases exist. Identifying pathogenic species is of epidemiological significance, and the treatment includes immune reconstitution by granulocyte-colony-stimulating factor, granulocyte macrophage-colony-stimulating factor and a combination of the most active species - specific antifungals, typically liposomal amphotericin-B and voriconazole. However, patient outcome is difficult to predict even with in vitro susceptibility with these drugs. Therefore, prevention methods and antifungal prophylaxis have to be taken seriously for these vulnerable patients by vigilant healthcare workers. The current available literature on PubMed and Google Scholar using search terms 'Fusarium', 'opportunistic invasive fungi' and 'invasive fusariosis' was summarised for this review.

Fungal peritonitis in peritoneal dialysis: a 34-year single centre evaluation

Backgound

Fungal peritonitis (FP) is one of the most important causes of peritoneal dialysis (PD) failure, often burdened by increased morbility and mortality. This study evaluates the clinical course of FP cases that arose between 1983 and 2016 in a single PD unit.

Methods

We conducted a retrospective observational analysis of FP episodes recorded in the Baxter POET (Peritonitis Organism Exit sites Tunnel infections) registry and clinical records. FP incidence rate, PD and patients’ survival and clinical characteristics of the study population were analysed, taking into account the evolution of clinical practice during the study period as a result of technical innovation, scientific evidence and guideline history.

Results

Fourteen FP cases (2.8%) were detected. The overall incidence of PD peritonitis was one episode/27 patient-months. Candida parapsilosis was the most frequently (50%) detected yeast. Seventy-five per cent of cases were considered secondary FP. This group experienced 2.6±1.7 bacterial peritonitis before FP, most frequently due to Staphylococcus and Enterococcus species. Most patients were treated with fluconazole for ≥8 days. All subjects were hospitalized for a median time of 25 days. Tenckhoff catheter removal occurred in all cases of FP and all patients were transferred to haemodialysis. Two patients died. From December 2010 to December 2016, no FP episodes were recorded.

Conclusions

FP is confirmed as a significant cause of PD drop out and increases patients’ mortality risk. Prompt diagnosis of FP, targeted antifugal therapy and rapid PD catheter removal are essential strategies for improved patient and PD survival.

Fungal peritonitis in patients undergoing peritoneal dialysis (PD) in Brazil: molecular identification, biofilm production and antifungal susceptibility of the agents

This paper presents data on fungal peritonitis (FP) in patients undergoing peritoneal dialysis (PD) at the University Hospital of Botucatu Medical School, São Paulo, Brazil. In a total of 422 patients, 30 developed FP, from which the medical records and the fungal isolates of 23 patient cases were studied. All patients presented abdominal pain, cloudy peritoneal effluent, needed hospitalization, had the catheter removed and were treated with fluconazole or fluconazole plus 5-flucitosine; six of them died due to FP. Concerning the agents, it was observed that Candida parapsilosis was the leading species (9/23), followed by Candida albicans (5/23), Candida orthopsilosis (4/23), Candida tropicalis (3/23), Candida guilliermondii (1/23), and Kodamaea ohmeri (1/23). All the isolates were susceptible to amphotericin B, voriconazole and caspofungin whereas C. albicans isolates were susceptible to all antifungals tested. Resistance to fluconazole was observed in three isolates of C. orthopsilosis, and dose-dependent susceptibility to this antifungal was observed in two isolates of C. parapsilosis and in the K. ohmeri isolate. Biofilm production estimates were high or moderate in most isolates, especially in C. albicans species, and low in C. parapsilosis species, with a marked variation among the isolates. This Brazilian study reinforces that FP in PD is caused by a diverse group of yeasts, most prevalently C. parapsilosis sensu stricto species. In addition, they present significant variation in susceptibility to antifungals and biofilm production, thus contributing to the complexity and severity of the clinical features.

Characteristics and outcomes of fungal peritonitis in a modern North American cohort

INTRODUCTION

Peritonitis remains a common complication of peritoneal dialysis (PD). Although representing only 1 - 12% of overall peritonitis in dialysis patients, fungal peritonitis (FP) is associated with serious complications, including technique failure and death. Only scarce data have been published regarding FP outcomes in modern cohorts in North America. In this study we evaluated the rates, characteristics and outcomes of FP in a major North American PD center.

METHODS

We conducted a retrospective cohort study including all fungal peritonitis episodes among peritoneal dialysis patients followed in a large PD center between January 2000 and February 2013. Our pre-specified endpoints included rates of FP, characteristics, outcomes and determinants of death.

RESULTS

Thirty-six episodes of FP were identified during the follow-up period (one episode per 671 patient-months), representing 4.5% of the total peritonitis events. Patients' mean age and peritoneal dialysis vintage were 61.3 ± 15.5 and 2.9 (1.5 - 4.8) years, respectively. Of the 36 episodes of FP, seven (19%) resulted in death and 17 (47%) led to technique failure with permanent transfer to hemodialysis. Surprisingly, PD was eventually resumed in 33% of cases with a median delay of 15 weeks (interquartile range 8 - 23) between FP and catheter reinsertion. In a univariable analysis, a higher Charlson comorbidity index (Odds ratio [OR] 3.25 per unit increase, 95% confidence interval [CI] 1.23 - 8.58) and PD fluid white blood cell (WBC) count greater than 3,000/mm(3) at presentation (OR 6.56, 95% CI 1.05 - 40.95) predicted death.

CONCLUSION

While fungal peritonitis is still associated with a high frequency of death and technique failure, one third of our patients eventually returned to PD. Patients with a high burden of comorbidities appear at higher risk of death. We postulate that the high mortality associated with FP is partially related to the severity of comorbidity among patients with FP, rather than the infection per se. Importantly, PD can be resumed in a significant proportion of cases.