Bacteria are single-celled microorganisms found throughout nature, including on and within the human body. The vast majority of bacteria are harmless or beneficial, but certain pathogenic bacteria can infect tissues, triggering an immune response and illness.
In cardiovascular medicine, bacteria are the cause of several serious conditions. Infective endocarditis occurs when bacteria enter the bloodstream and colonise the heart’s inner lining or valves, causing infected deposits (vegetations) that can damage valve function and embolise to other organs. Sepsis (a life-threatening dysregulated response to infection) caused by bacteria can compromise cardiac function and may precipitate cardiac arrest. Bacterial pericarditis can occur in immunocompromised patients or following cardiac surgery.
Patients with structural heart disease or implanted cardiac devices (pacemakers, ICDs, and prosthetic valves) are at elevated risk of serious bacterial infections involving these structures. The bacteria most commonly implicated in device-related infections include Staphylococcus aureus (including MRSA) and Staphylococcus epidermidis. Dental and other procedures that may cause transient bacteraemia should be discussed with a cardiologist for those with relevant cardiac risk.
Antibiotics are the primary treatment for bacterial infections. Choosing the correct antibiotic requires identifying the causative organism and testing its sensitivity. Blood cultures (laboratory analysis of blood samples to identify bacteria and their antibiotic sensitivities) should be taken before antibiotics are started wherever possible in serious infections.
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