Vitamin K is a lipid-soluble vitamin that is normally maintained within appropriate levels by means of dietary intake and bacterial production in the intestinal microflora. It holds a central role in coagulation homeostasis, and thus its depletion leads to hypocoagulation and haemorrhagic diathesis. The association of antibiotic therapy and vitamin E supplementation with vitamin K deficiency was previously described in animal experiments, clinical studies, and case reports. Broad-spectrum antibiotic therapy potentially leads to intestinal microflora dysbiosis and restriction of vitamin K-producing bacterial populations, resulting in decreased vitamin K levels, whereas antibiotics of the cephalosporin class with 1-N-methyl-5-thiotetrazole (NMTT) or 2-methyl-1,3,4-thiadiazole (MTD) side groups inhibit vitamin K function. Vitamin E supplementation interferes with both the bioavailability and function of vitamin K, yet its mechanisms are not fully understood. We present the case of a 45-year-old male patient, with a history of epilepsy and schizophrenia, catatonically incapacitated and immobilised, who was hospitalised in our centre for the investigation and management of aspiration pneumonia. He demonstrated a progressively worsening prolongation of international normalised ratio (INR), which was attributed to both broad-spectrum antibiotic therapy and vitamin E supplementation and was reversed upon administration of vitamin K. We highlight the need for close monitoring of coagulation parameters in patients receiving broad-spectrum antibiotic therapy, especially those with underlying malnutritive or malabsorptive conditions, and we further recommend the avoidance of NMTT- or MTD-containing antibiotics or vitamin E supplementation, unless absolutely necessary, in those patients.

An elderly male, with a recent COVID-19 infection and cardiovascular comorbidities, experienced a prolonged hospitalization due to a periprosthetic joint infection (PJI) and bacteremia, post hip hemiarthroplasty. Despite the initial clinical improvement while on targeted antimicrobial therapy, the patient later developed a low-grade fever and signs of myelosuppression. In the May–Grünwald–Giemsa stain of peripheral blood smear (PBS), pseudohyphae among red blood cells (RBCs) and phagocytosed blastospores in neutrophils and monocytes were detected, indicating candidemia rather than contamination of the stain. Echinocandin treatment was immediately initiated, and Candida albicans was identified from the blood culture, using multiplex polymerase chain reaction (PCR). Despite the early initiation of antifungal therapy and the removal of the central venous line (CVL), the patient passed away within 24 h. Candidemia is a leading cause of nosocomial bloodstream infections with high morbidity and mortality and is associated with multiple risk factors including surgery, CVLs, prolonged hospitalization, concomitant bacterial infection, broad-spectrum antibiotics, and immunosuppression. Isolation from blood cultures remains the gold standard for diagnosing candidemia. Detection of candidemia by PBS is extremely rare, requires an experienced microscopist, and is considered to be an emergency. Clinical suspicion, early laboratory identification, and immediate clinician notification are crucial for prompt antifungal treatment.

An elderly male, with recent COVID-19 and cardiovascular comorbidities, had a prolonged hospitalisation due to periprosthetic joint infection and bacteraemia, post hip hemiarthroplasty. Despite the initial clinical improvement while under targeted antimicrobial therapy, low-grade fever and signs of myelosuppression later occurred. In the May-Grünwald-Giemsa stain of peripheral blood smear (PBS), pseudohyphae among RBCs and phagocytosed blastospores in neutrophils and monocytes were detected, indicating candidaemia and not contamination of the stain. Echinocandin treatment was immediately initiated, and Candida albicans was identified, using multiplex PCR, from the obtained blood cultures. Despite the early initiation of antifungal therapy and the removal of the CVL (central venus line), the patient passed away within the next twenty-four hours. Candidaemia is a leading cause of nosocomial bloodstream infections with very high morbidity and mortality and is associated with multiple risk factors (surgery, CVLs, prolonged hospitalization, concomitant bacterial infection, broad-spectrum antibiotics, immunosuppression). The isolation from blood cultures is the gold standard for candidaemia diagnosis. Detection of candidaemia by PBS is extremely rare, requires an experienced microscopist, and is considered to be an emergency. Clinical suspicion, early laboratory identification, and immediate clinician notification can lead to prompt antifungal treatment.