Which of the following is NOT a hospital-acquired infection?

Cystitis, often referred to as a urinary tract infection (UTI), is typically caused by bacteria entering the urinary tract and can occur in both hospital and community settings. While it is indeed possible for cystitis to develop in patients who are hospitalized, it is not exclusive to healthcare settings. In contrast, central line-associated bloodstream infections (CLABSI), catheter-associated urinary tract infections (CAUTI), and methicillin-resistant Staphylococcus aureus (MRSA) are considered hospital-acquired infections because they are directly linked to medical interventions or the hospital environment.

CLABSI and CAUTI are specifically tied to the insertion of medical devices, which poses risk factors for infection in hospitalized patients. MRSA, while it can be found in the community, is also a significant concern in hospitals, where it can spread rapidly due to close patient contact and shared environments. Therefore, identifying cystitis as the correct answer highlights its nature as a more general condition, not necessarily acquired in a hospital setting, unlike the other listed infections.