To the Editor—Nosocomial infections (NIs), also known as healthcare-associated infections and hospital-acquired infections, with a pooled prevalence of 10.1%, are considered to be serious public health problems around the world.Reference Allegranzi, Nejad and Combescure ¹ The NI-related burden is unknown because of lack reliable data, lack of surveillance systems and the complexity of corresponding NI outcomes. ²

Healthcare systems use different approaches to monitoring NIs. ^{3 –} Reference Tabatabaei, Pour and Osmani ⁷ Generally, surveillance methods are categorized under the umbrellas of active, passive, and sentinel surveillance methods.Reference Horan and Gaynes ⁸ At present, hospitals implement passive surveillance approaches because of feasibility and low cost. However, the quality of this methodology is in question; underreporting and lack of timeliness are the main challenges. In contrast to the passive approach of NI surveillance systems, active ones do not face the challenge of real-time detection of hospital-acquired infection and provide high-quality data on the trends and burdens of NIs. This approach requires extensive resources.

Lessons learned from the implementation of passive approaches to NI surveillance, especially in low- and middle-income countries, have revealed the necessity of applying other methods. Implementation of integrated sentinel surveillance methods using active approaches at selected hospitals and healthcare facilities provides reliable data about the epidemiological profiles of hospital-acquired infections with limited resources. Selecting representative hospitals can contribute to an appropriate understanding of NI-related burden.