Candida Endocarditis: A Review of the Pathogenesis, Morphology, Risk Factors, and Management of an Emerging and Serious Condition

Practical Guidance for Clinical Microbiology Laboratories: Microbiologic diagnosis of implant-associated infections

SUMMARYImplant-associated infections (IAIs) pose serious threats to patients and can be associated with significant morbidity and mortality. These infections may be difficult to diagnose due, in part, to biofilm formation on device surfaces, and because even when microbes are found, their clinical significance may be unclear. Despite recent advances in laboratory testing, IAIs remain a diagnostic challenge. From a therapeutic standpoint, many IAIs currently require device removal and prolonged courses of antimicrobial therapy to effect a cure. Therefore, making an accurate diagnosis, defining both the presence of infection and the involved microorganisms, is paramount. The sensitivity of standard microbial culture for IAI diagnosis varies depending on the type of IAI, the specimen analyzed, and the culture technique(s) used. Although IAI-specific culture-based diagnostics have been described, the challenge of culture-negative IAIs remains. Given this, molecular assays, including both nucleic acid amplification tests and next-generation sequencing-based assays, have been used. In this review, an overview of these challenging infections is presented, as well as an approach to their diagnosis from a microbiologic perspective.

Candida tropicalis endocarditis on the aortic valve with coexisting meningitis in a patient with multiple risk factors - What to do?

A 65-year-old female patient with Candida tropicalis infective endocarditis on the aortic valve underwent aortic valve replacement. In the postoperative period a head computer tomography revealed a left temporal arachnoid cyst, diagnosed as fungal meningitis. We outline a successful treatment approach for this high-risk patient.

Candida endocarditis: Update on management considerations

The rise in incidence rates of invasive candidiasis warrants an increase in attention and efforts toward preventing and treating this virulent infection. Cardiac involvement is one of the most feared sequelae and has a poor prognosis. Despite the introduction of several novel antifungal agents over the past quarter century, complications and mortality rates due to Candida endocarditis have remained high. Although fungal endocarditis has a mechanism similar to bacterial endocarditis, no specific diagnostic criteria or algorithm exists to help guide its management. Furthermore, recent data has questioned the current guidelines recommending a combined approach of antifungal agents with surgical valve or indwelling prostheses removal. With the emergence of multidrug-resistant Candida auris, a focus on improved prophylactic measures and management strategies is necessary.

Dual wave of neutrophil recruitment determines the outcome of C. albicans infection

Candida albicans is a ubiquitous fungus that can cause superficial and systemic infections in humans. Neutrophils play a crucial role in controlling C. albicans infections. When C. albicans enters the bloodstream, it tends to get trapped in capillary vessels. However, the behavior of neutrophils in combating capillary-residing fungi has not been fully characterized. In this study, we used transgenic mice and whole mount imaging to investigate the growth of C. albicans and its interaction with innate immune cells in different organs. We observed that C. albicans rapidly grows hyphae within hours of infection. Following intravenous infection, we observed two waves of neutrophil recruitment, both of which significantly contributed to the elimination of the fungi. The first wave of neutrophils was induced by complement activation and could be prevented by C5aR blockade. Interestingly, we discovered that the fungicidal effect in the lungs was independent of adhesion molecules such as Mac-1, LFA-1, and ICAM-1. However, these molecules played a more significant role in the optimal killing of C. albicans in the kidney. Importantly, the initial difference in killing efficiency resulted in significantly reduced survival in knockout mice lacking these adhesion molecules. We identified a second wave of neutrophil recruitment associated with hyphal growth and tissue damage, which was independent of the aforementioned adhesion molecules. Overall, this study elucidates the dual wave of neutrophil recruitment during C. albicans infection and highlights the importance of early fungal clearance for favorable disease outcomes.

An unusual case of Candida parapsilosis endocarditis of the native tricuspid valve secondary to a tunneled dialysis catheter

Candida endocarditis is a severe disease associated with high mortality rates. Candida parapsilosis is frequently identified as the causative pathogen in intravenous drug users and is commonly associated with nosocomial infections, primarily due to its ability to form biofilms on catheters or other foreign bodies. Here, we present a rare case of Candida parapsilosis endocarditis affecting the native tricuspid valve in a 35-year-old male patient with end-stage chronic kidney disease (Stage V), who had a suspected fungal infection related to the left cervical catheter. The patient received treatment with caspofungin and underwent excision of a verrucous tumor on the tricuspid valve. Despite encountering postoperative complications, the patient was discharged on fluconazole treatment and scheduled for follow-up. Candida endocarditis poses a clinical challenge that necessitates a multidisciplinary approach and tailored management due to its infrequent occurrence and higher mortality rate compared to bacterial endocarditis.

Candid and Fragile: A Case Report of Infective Endocarditis From Candida albicans and Bacteroides fragilis

Infective endocarditis (IE) remains a significant cause of mortality worldwide and reported cases are continuing to increase annually. We describe a case of a patient who would undergo coronary artery bypass grafting (CABG) with bioprosthetic aortic valve replacement complicated by postop gastrointestinal bleeding requiring partial colectomy with ileocolic anastomosis who would later present with fever, dyspnea, and persistently positive blood cultures who would be found to have tricuspid valve endocarditis from Candida and Bacteroides species that was successfully treated with a combination of surgical resection and antimicrobial therapy.

Prosthetic valve endocarditis due to Candida parapsilosis - a rare case report

Fungal endocarditis is a rare and fatal condition, most frequently caused by species of the genera Candida and Aspergillus. Fever and changing heart murmur are the most common clinical manifestations. The diagnosis of fungal endocarditis is challenging, with prosthetic valve endocarditis being extremely difficult to diagnose. The optimal management of the condition still remains debatable. We present a case of prosthetic valve endocarditis caused by Candida parapsilosis, managed empirically with liposomal amphotericin B, which was later shifted to combination therapy with high-dose echinocandin and fluconazole, but had a fatal outcome because the patient could not undergo timely surgical intervention. Treating C. parapsilosis endocarditis cases is difficult because of their biofilm production on native and prosthetic heart valves. A combined approach consisting of a high index of clinical suspicion, early diagnosis using serological markers followed by culture or PCR and prompt initiation of appropriate antifungals may aid in improving outcomes.

Contemporary comparison of infective endocarditis caused by Candida albicans and Candida parapsilosis: a cohort study

Among 1655 consecutive patients with infective endocarditis treated from 1998 to 2020 in three tertiary care centres, 16 were caused by Candida albicans (CAIE, n = 8) and Candida parapsilosis (CPIE, n = 8). Compared to CAIE, CPIE were more frequently community-acquired. Prosthetic valve involvement was remarkably more common among patients with CPIE. CPIE cases presented a higher rate of positive blood cultures at admission, persistently positive blood cultures after antifungals initiation and positive valve cultures. All patients but four underwent cardiac surgery. Urgent surgery was more frequently performed in CPIE. No differences regarding in-hospital mortality were documented, even after adjusting for therapeutic management.

Environmental, Microbiological, and Immunological Features of Bacterial Biofilms Associated with Implanted Medical Devices

The spread of biofilms on medical implants represents one of the principal triggers of persistent and chronic infections in clinical settings, and it has been the subject of many studies in the past few years, with most of them focused on prosthetic joint infections. We review here recent works on biofilm formation and microbial colonization on a large variety of indwelling devices, ranging from heart valves and pacemakers to urological and breast implants and from biliary stents and endoscopic tubes to contact lenses and neurosurgical implants. We focus on bacterial abundance and distribution across different devices and body sites and on the role of environmental features, such as the presence of fluid flow and properties of the implant surface, as well as on the interplay between bacterial colonization and the response of the human immune system.

What Do We Know about Candida auris? State of the Art, Knowledge Gaps, and Future Directions

Candida auris has unprecedently emerged as a multidrug resistant fungal pathogen, considered a serious global threat due to its potential to cause nosocomial outbreaks and deep-seated infections with staggering transmissibility and mortality, that has put health authorities and institutions worldwide in check for more than a decade now. Due to its unique features not observed in other yeasts, it has been categorised as an urgent threat by the Centers for Disease Control and Prevention and other international agencies. Moreover, epidemiological alerts have been released in view of the increase of healthcare-associated C. auris outbreaks in the context of the COVID-19 pandemic. This review summarises the current evidence on C. auris since its first description, from virulence to treatment and outbreak control, and highlights the knowledge gaps and future directions for research efforts.

Relapsing Candida parapsilosis Endocarditis With Septic Embolization: A Case Report

Candida endocarditis is a rare infection that is becoming an emerging and growing health concern, especially among risk groups such as the elderly and the immunosuppressed. It is associated with high morbidity and mortality. Dilemmas about Candida endocarditis treatment are still around, particularly about the treatment options and their duration. We report a case of Candida parapsilosis prosthetic valve endocarditis with septic embolisms. An elderly male patient with a biological prosthetic valve presented with fever and constitutional symptoms. Abdominal computed tomography (CT) showed an area suggestive of splenic emboli. Transesophageal echocardiography showed a vegetation attaching to the prosthetic valve. Due to several comorbidities, he was not considered a candidate for surgical treatment. He was treated with antifungal drugs (liposomal amphotericin B and caspofungin) and was discharged with per os fluconazole. Later he presented with evidence of lumbar spondylodiscitis due to septic embolization and relapsing fungemia with multidrug-resistant isolates was documented. Unfortunately, the patient outcome was ill-fated and he died in hospital due to sepsis-related to the candidemia and also nosocomial urinary sepsis. Here, we illustrate the complexity of diagnosing and managing fungal endocarditis due to its complications and poor prognosis.

Candida albicans-The Virulence Factors and Clinical Manifestations of Infection

Candida albicans is a common commensal fungus that colonizes the oropharyngeal cavity, gastrointestinal and vaginal tract, and healthy individuals' skin. In 50% of the population, C. albicans is part of the normal flora of the microbiota. The various clinical manifestations of Candida species range from localized, superficial mucocutaneous disorders to invasive diseases that involve multiple organ systems and are life-threatening. From systemic and local to hereditary and environmental, diverse factors lead to disturbances in Candida's normal homeostasis, resulting in a transition from normal flora to pathogenic and opportunistic infections. The transition in the pathophysiology of the onset and progression of infection is also influenced by Candida's virulence traits that lead to the development of candidiasis. Oral candidiasis has a wide range of clinical manifestations, divided into primary and secondary candidiasis. The main supply of C. albicans in the body is located in the gastrointestinal tract, and the development of infections occurs due to dysbiosis of the residential microbiota, immune dysfunction, and damage to the muco-intestinal barrier. The presence of C. albicans in the blood is associated with candidemia-invasive Candida infections. The commensal relationship exists as long as there is a balance between the host immune system and the virulence factors of C. albicans. This paper presents the virulence traits of Candida albicans and clinical manifestations of specific candidiasis.

A case series of medically managed Candida parapsilosis complex prosthetic valve endocarditis

Background

In recent years, Candida parapsilosis is recognized as a species complex and is composed of Candida parapsilosis sensu stricto, Candida orthopsilosis and Candida metapsilosis. Candida parapsilosis complex prosthetic valve endocarditis (PVE) is rare and the survival rate is still low despite of optimal therapeutic strategies. In our report, it is novel to report cases as Candida parapsilosis complex PVE at species and identify Candida parapsilosis using MALDI-TOF MS.

Case presentation

A series of 4 cases of Candida parapsilosis complex PVE from our institution was reported. Three were infected by Candida parapsilosis sensu stricto and one was infected by Candida metapsilosis. The condition of two cases got better and the other died.

Conclusions

More attention should be paid to Candida parapsilosis complex PVE and early diagnosis and prompt antibiotic therapy may play a role in the treatment for Candida parapsilosis complex PVE. It is recommended to identify Candida parapsilosis complex at species level and MALDI-TOF MS as an easy, fast and efficient identification method is worth promoting in clinical microbiology

Caspofungin Effects on Electrocardiogram of Mice: An Evaluation of Cardiac Safety

Caspofungin is an echinocandin, exhibiting efficacy against most Candida species invasive infection. Its cardiotoxicity was reported in isolated rat heart and ventricular myocytes, but in vivo and clinical studies are insufficient. Our objective was to evaluate caspofungin in vivo cardiac effects using an efficacious dose against Candida albicans. Female Swiss mice were infected with C. albicans, and treated with caspofungin, 5 or 10 mg/kg, intraperitoneal along 5 days. Survival rate and colony-forming units (CFU) into vital organs were determined. For cardiac effects study, mice were treated with caspofungin 10 mg/kg, and electrocardiogram (ECG) signal was obtained on C. albicans-infected mice, single dose-treated, and uninfected mice treated along 5 days, both groups to measure ECG intervals. Besides, ECG was also obtained by telemetry on uninfected mice to evaluate heart rate variability (HRV) parameters. The MIC for caspofungin on the wild-type C. albicans SC5314 strain was 0.3 μg/ml, indicating the susceptible. Survival rate increased significantly in infected mice treated with caspofungin compared to mice treated with vehicle. None of the survived infected mice presented positive CFU after treatment with 10 mg/kg. C. albicans infection induced prolongation of QRS, QT, and QTc intervals; caspofungin did not alter this effect. Caspofungin induced increase of PR and an additional increase of QRS after 24 h of a single dose in infected mice. No significant alterations occurred in ECG intervals and HRV parameters of uninfected mice, after caspofungin treatment. Caspofungin showed in vivo cardiac relative safety maintaining its antifungal efficacy against C. albicans.

Plant-Derived Substances in the Fight Against Infections Caused by Candida Species

Yeast-like fungi from the Candida genus are predominantly harmless commensals that colonize human skin and mucosal surfaces, but under conditions of impaired host immune system change into dangerous pathogens. The pathogenicity of these fungi is typically accompanied by increased adhesion and formation of complex biofilms, making candidal infections challenging to treat. Although a variety of antifungal drugs have been developed that preferably attack the fungal cell wall and plasma membrane, these pathogens have acquired novel defense mechanisms that make them resistant to standard treatment. This causes an increase in the incidence of candidiasis and enforces the urgent need for an intensified search for new specifics that could be helpful, alone or synergistically with traditional drugs, for controlling Candida pathogenicity. Currently, numerous reports have indicated the effectiveness of plant metabolites as potent antifungal agents. These substances have been shown to inhibit growth and to alter the virulence of different Candida species in both the planktonic and hyphal form and during the biofilm formation. This review focuses on the most recent findings that provide evidence of decreasing candidal pathogenicity by different substances of plant origin, with a special emphasis on the mechanisms of their action. This is a particularly important issue in the light of the currently increasing frequency of emerging Candida strains and species resistant to standard antifungal treatment.