Candida kefyr is a yeast that can cause opportunistic infections in humans, especially in immunocompromised patients, such as those with hematological malignancies or stem cell transplantation. The human pathogen C. kefyr’s epidemiology needs to be better understood due to the lack of well-defined studies, particularly from Middle Eastern countries. However, some studies have reported the prevalence and distribution of C. kefyr among candidemia cases in different regions of the world. 

Here are some of the findings: 

• In Kuwait, C. kefyr accounted for 2.8% of all Candida isolates recovered from the bloodstream and other specimens during 2011–2018. C. kefyr was more common in males than females and showed high susceptibility to most antifungal agents. 
• In Egypt, C. kefyr was detected in 0.5% of candidemia cases in adults and 1.1% in pediatrics in two teaching university hospitals between 2019 and 2020. C. kefyr was among the uncommon Candida species that showed an increased prevalence in recent years. 
• In Canada, C. kefyr was responsible for 4.8% of candidemia episodes in patients with hematological malignancies in a tertiary care hospital in Montreal during 2006–2011. C. kefyr infection was associated with prominent summer seasonality and higher rates of central venous catheter removal and antifungal treatment failure.

• Kingdom: Fungi 
• Division: Ascomycota 
• Class: Saccharomycetes 
• Order: Saccharomycetales 
• Family: Saccharomycetaceae 
• Genus: Candida 
• Species: Candida kefyr

The structure of C. kefyr can be described in five points as follows: 

• C. kefyr has a cell wall composed of mannoproteins, glucans, and chitin, which provide rigidity and protection. 
• C. kefyr has a plasma membrane that contains ergosterol, which is a target for antifungal agents. 
• C. kefyr has a nucleus that contains eight pairs of chromosomes and a nucleolus that synthesizes ribosomal RNA. 
• C. kefyr has various organelles, such as mitochondria, vacuoles, endoplasmic reticulum, Golgi apparatus, and peroxisomes, that perform different metabolic functions. 
• C. kefyr can switch between yeast and pseudohyphal forms, which may affect its adherence, invasion, and virulence. 

Candida kefyr is a yeast that can cause infections in immunocompromised patients, especially those with hematological malignancies. It is also used in the production of fermented dairy products. 

According to a study by Al-Siyabi et al., there are four antigenic types of C. kefir based on the agglutination patterns of their cell wall mannoproteins.

These are: 

• Type I: Agglutinates with anti-C. kefyr serum and anti-C. albicans serum 
• Type II: Agglutinates with anti-C. kefyr serum only 
• Type III: Agglutinates with anti-C. albicans serum only 
• Type IV: Does not agglutinate with either serum. 

The authors found that type II was the most prevalent (54.5%) among clinical isolates of C. kefyr, followed by type I (27.3%), type III (9.1%), and type IV (9.1%). They also observed that type II was more resistant to antifungal drugs than the other types. 

The pathogenesis of C. kefyr are: 

• Morphological switching: C. kefyr can switch between yeast and pseudohyphal forms, which may affect its adherence, invasion, and virulence. 
• Biofilm formation: C. kefyr can form biofilms on medical devices, such as catheters, which can protect it from host defenses and antifungal agents. 
• Extracellular enzymes: C. kefyr can produce hydrolytic enzymes, such as phospholipases and proteases, which can degrade host cell membranes and proteins, facilitating its invasion and tissue damage. 
• Adherence and invasion: C. kefyr can adhere to and invade various host cells, such as epithelial, endothelial, and phagocytic cells, using adhesins and invasins, which are surface proteins that mediate the interaction between the yeast and the host. 
• Immune evasion: C. kefyr can evade the host immune system by various mechanisms, such as phenotypic switching, coating with platelets, or modulating the cytokine response. 

The host defenses of Candida kefyr are the mechanisms by which the human body protects itself from this yeast infection. C. kefyr is a commensal organism that can become opportunistic under certain conditions, such as immunosuppression, chemotherapy, or antibiotic therapy. The host defenses of C. kefyr can be divided into two categories: innate and adaptive immunity.

• Innate immunity: The first layer of protection against C. kefyr and involves physical barriers, such as mucosal membranes and skin, as well as cellular and molecular elements, such as neutrophils, macrophages, dendritic cells, natural killer cells, complement system, and cytokines. These components recognize and eliminate C. kefyr by various mechanisms, such as phagocytosis, oxidative burst, lysosomal enzymes, antimicrobial peptides, and inflammation. The innate immunity also activates adaptive immunity by presenting fungal antigens to T and B cells. 
• Adaptive immunity: This is the second line of defense against C. kefyr and involves the specific recognition and memory of C. kefyr by T and B cells. There are two categories of adaptive immunity: humoral immunity and cellular immunity. The process of humor immunity entails B lymphocytes producing antibodies that can attach to and neutralize C. kefir or stimulate phagocytes and the complement system. The process of cellular immunity includes T-cell activation, which can produce cytokines and cytotoxic molecules that can modulate the immune response and kill C. kefir-infected cells. Adaptive immunity also provides long-term protection against C. kefir by generating memory cells that can quickly respond to future exposures. 

Candida kefyr is a yeast that can cause opportunistic infections in humans, especially in immunocompromised patients. It is usually a commensal organism that colonizes the skin, mucous membranes, and gastrointestinal tract. Still, it can become pathogenic under certain conditions, such as prolonged use of antibiotics, chemotherapy, or immunosuppressive therapy. 

Some of the clinical manifestations of Candida kefyr infection are: 

• Funguria: The presence of Candida in the urine could point to a kidney or bladder infection. Hospitalized patients frequently develop fungi, which are usually benign, but they can lead to invasive kidney infections, which are challenging to treat. 
• Candidemia: The presence of Candida in the bloodstream. It can result in systemic infection and spread to other organs. Candidemia is associated with a high mortality rate and often occurs in neutropenic patients with hematological malignancies or stem cell transplantation. 
• Candida oesophagitis: The inflammation of the esophagus caused by Candida, which can cause dysphagia, odynophagia, chest pain, and weight loss. Candida oesophagitis is often seen in patients with AIDS or other causes of impaired cell-mediated immunity. 
• Peritonitis: The inflammation of the peritoneum, the membrane that lines the abdominal cavity, caused by Candida. Peritonitis can cause abdominal pain, fever, nausea, vomiting, and septic shock. Peritonitis can occur as a complication of peritoneal dialysis, abdominal surgery, or bowel perforation. 
• Other manifestations: Candida kefyr can also cause infections of the mouth, skin, nails, genitals, joints, heart, brain, and bones, depending on the site of entry and the host’s immune status. 

Culture and Identification: 

• most popular and trustworthy technique. 
• Take a sample from an infected site (blood, urine, tissue, etc.). 
• Culture on suitable medium (e.g., Sabouraud dextrose agar). 
• Colonies appear in 48 hours, with cream-colored, smooth, convex characteristics. 
• Confirm identification with biochemical tests like germ tube, carbohydrate assimilation, or API 20C AUX system. 

Microscopy: 

• Rapid method, especially for candiduria or candidemia. 
• Examine wet mount or Gram-stained smear under a microscope. 
• Look for oval, elongated, narrow yeast cells and pseudohyphae of C. kefyr. 
• May detect coexisting microorganisms. 

Molecular Techniques: 

• Advanced and sensitive to invasive or resistant infections. 
• Take out the sample’s DNA. 
• Amplify DNA using PCR, real-time PCR, multiplex PCR, or LAMP. 
• Detect amplified DNA through gel electrophoresis, hybridization, or sequencing. 
• Provides information on species, strain, genotype, and antifungal susceptibility/resistance of C. kefyr. 

Maintaining Good Hygiene: 

• Wash hands frequently. 
• Keep skin and mucous membranes clean and dry. 
• Don’t share personal things like toothbrushes, towels, or razors. 

Avoiding Unnecessary Antibiotics: 

• Use antibiotics only when prescribed by a doctor. 
• Follow the prescribed duration to prevent microbiome imbalance and C. kefir overgrowth. 

Controlling Blood Sugar Levels: 

• Monitor and control blood sugar levels, especially in diabetes patients. 
• Utilize diet, exercise, and medication for effective management. 

Strengthening the Immune System: 

• Boost the immune system with a balanced diet. 
• Ensure adequate sleep, manage stress, and avoid smoking and alcohol. 

Removing/Changing Indwelling Devices: 

• Remove or change indwelling devices, such as catheters, promptly. 
• Ensure proper cleaning and adherence to medical guidelines. 

• In vitro antifungal susceptibility patterns of planktonic and sessile Candida kefyr clinical isolates | Medical Mycology | Oxford Academic (oup.com) 
• Candida kefyr in Kuwait: Prevalence, antifungal drug susceptibility and genotypic heterogeneity | PLOS ONE