If the immune system is suppressed by the antibiotic as a side effect, the infection can run out of control and the patient may die because of it. Fortunately, this does not happen often because there are new and better antibiotics without this severe side effect. Another example is the treatment of cancer. Radiation therapy will increase the likelihood of getting a cure for the patient's current cancer, but it also may increase the patient's risk of getting radiation-induced cancer later on in life. Hospitals can be dangerous zones to unsuspecting guests.
Nosocomial infections are hospital-acquired infections.
Dr. Robert N. Butler expressed, in a Geriatrics editorial, that nosocomial infections victimize one out of every twenty patients with a new infection in the hospital. Viruses, bacteria, protozoa, or fungi are usually the culprits. Fortunately, the latter does not happen too often because infection control is so strict nowadays. First of all, hospitalized patients are usually sicker and more immunocompromised. Patients also suffer impaired defenses due to a break in skin via an intravenous line, a chest tube to drain a lung abscess, and other transcutaneous monitoring devices.