Cotrimoxazole is a commonly used antimicrobial agent which is traditionally indicated in the management of pneumocystis infection of which HIV and immunosuppressed individuals are at high risk. Furthermore, it can be used on the long term for prophylactic indications. Hypoglycaemia following commencement of cotrimaoxazole is a rare adverse effect which was first described in 1988. We describe a case of hypoglycaemia shortly following initiation of cotrimoxazole indicated as long-term prophylaxis on a background of Churg-Strauss syndrome. The patient was symptomatic for hypoglycaemia despite simultaneous use of high-dose prednisolone; however, the hypoglycaemia did not require a hospital admission. We will explore the risk factors, monitoring requirements, and the mechanism by which co-trimoxazole induces hypoglycaemia. 1. Introduction Cotrimoxazole (combination of trimethoprim and sulfamethoxazole) is an antimicrobial agent which has both prophylactic and therapeutic indications for Pneumocystis jirovecii infection which represents a high risk among immunosuppressed patients. Pneumocystis is an opportunistic infection which often presents as fever, nonproductive cough, and dyspnoea in HIV patients although symptoms are not as marked and with a relatively shorter duration in immunocompromised patients for reasons other than HIV . It is typically identified on microscopy which can be obtained from bronchoscopy with bronchoalveolar lavage. Mortality associated with pneumocystis infection has been linked to mechanical ventilation needs or failure in antimicrobial treatment . Cotrimoxazole is commonly used as long term prophylaxis in HIV-infected patients to promote increased survival . Furthermore, it has been trialed with positive results in the management of drug-resistant superbugs . The efficacy of cotrimoxazole has made it ideal as first line management in both treatment and prophylaxis of pneumocystis infection. Despite this, there are high rates of adverse effects and potential for P. jirovecii drug resistance . Alternative chemoprophylactic agents for pneumocystis infections include pentamidine and dapsone. The most common adverse effect associated with cotrimoxazole is gastric discomfort and reduced appetite. We discuss a case of cotrimoxazole-induced hypoglycaemia initiated in a patient with Churg-Strauss syndrome. Of the case reports we analysed detailing hypoglycaemia secondary to cotrimoxazole in our discussion section the patients were either on high dose cotrimoxazole or were otherwise elderly frail and had renal impairment or
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