Title : Aspergillosis in diabetic patients: Causes, epidemiology, diagnostic challenges and management strategies
Abstract:
Diabetes is a chronic metabolic disease characterised by high blood sugar levels (HbA1c > 6.5%), resulting from the body’s in ability to produce or properly use insulin hormone which regulates blood glucose. It is characterized by 4 Ps-polyuria, polydipsia, polyphagia and polyneuropathy. It is an emerging disease growing at a fast rate of 46%. Globally, 589 million adults are living with diabetes which would reach 853 million by 2050. Aspergillosis is an opportunistic fungal infection of lungs caused by Aspergillus fumigatus. A. terreus and A. flavus. A. fumigatus is the main causative agent worldwide. Aspergillus is an ascomycetous saprophytic large genus with over 180 species but fewer than 40 of them are known to cause Infections in humans. Aspergillus spp. are characterised by colonial morphology on SDA, uniseriate or biseriate arrangement of phialides on vesicle.
Pathogenesis occurs by inhaling airborne spores which are ubiquitous widely prevalent in the external and internal environments (indoors & outdoors), soil, compost, dead and decaying vegetation, phylloplane, building materials, household dusts and stored foods due to enormous conidial production. The symptoms range from mild, asthma- like reactions to invasive infections of lungs resulting from fever, fatigue, breathlessness, chest pain, bloody cough, sometimes severe bleeding. Aspergillosis is of three types: allergic bronchopulmonary aspergillosis (ABPA) causing wheezing, cough, and shortness of breath; Chronic pulmonary aspergillosis (CPA)-long term infection often forming a fungal ball (aspergilloma) often confused with TB caused by Mycobacterium tuberculosis; and Invasive aspergillosis - where the infection spreads beyond lungs to other organs involving brain, kidneys, and bones and is life - threatening. Cutaneous aspergillosis may also occur through contaminated medical devices.
Aspergillosis is one of those most rapidly progressing fatal mycoses, especially with the emerging resistance to antifungal drugs (e.g., azoles) in Aspergillus fumigatus, the main treatment for aspergillosis. Globally, over 4.8 million people have ABPA, and about 2 million people are affected annually with mortality rates often exceeding 50% in ICU settings. Diabetics have a 27-40% higher risk of developing IPA due to hyperglycemia- induced impairment of immune system (affecting phagocytic ability of white blood cells, the granulocyte). Aspergillosis is diagnosed by chest X-rays / CT scans, biopsy, blood tests and sputum sample examinations. Direct microscopy of tissue samples; Fungal culturing on Sabouraud dextrose agar (SDA) incubated at 37°C and lactophenol cotton blue (LCB) mount examinations for septate hyphae, and columnar conidial heads and uniseriate flask -shaped phialides, producing unicellular spherical conidia (2.5-3µm) from the blue- green to smoky -grey, velvety colonies. Galactomannan antigen testing for serum and bronchoalveolar lavage fluid; Beta- d- glucan assay to detect cell wall component of Aspergillus; and PCR assay of tissues and bronchoalveolar lavage fluids. Management of aspergillosis in diabetics often requiring prompt diagnosis, and strict glycemic control (HbA1c) through antidiabetic drugs (e.g., metformin, semaglutide, gliptins, glimepiride) and treatment by antifungal therapy and surgical debridement of necrotic tissues to improve the low survival rates.
