en Infectious diseases and public health Infectious diseases and public health Original article Original article <b><span style="font-size:10.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">Introduction: </span></span></span></b><span style="font-size:10.0pt"><span style="line-height:115%"><span new="" roman="" style="font-family:" times="">Nosocomial respiratory infections are a significant cause of mortality in hospitalized patients in Middle East countries. This study assesses the prevalence of nosocomial respiratory infection and associated factors as a tool for early diagnosis among intensive care unit (ICU) patients at risk for mortality. M<b>ethods: </b>From January to November 2021, 357 patients with more than 72 h hospitalization in ICU were monitored. Respiratory samples were examined for the presence of microbial isolates using clinical microbiology procedures based upon microscopic morphology, cultural and PCR methods. Demographic data were collected, including age, gender, date of hospitalization, underlying diseases, date of death, and laboratory data. <b>Results:</b> Out of fifty-three positive cultures, 18 samples (34%) were positive for fungal isolates, and the rest were positive for bacterial isolates. The most common bacterial and fungal isolates were <em>Streptocossus Pyogenes</em> (17.9%) and <i>Candida albicans</i> (22.5%). Of the infected patients, 67.9% were male, 39.62 % had kidney diseases, and 15.09% died due to nosocomial infections. The results also showed that the tumor necrosis factor &alpha; and complement component 3 levels were significantly associated with the incidence of respiratory fungal or bacterial infections (<i>P</i><0.05). <b>Conclusions:</b> The rate of respiratory nosocomial infection in ICU patients was high. It is essential to implement control measures such as managing the length of hospital stay and examining the patient&#39;s immune factors to reduce the risk of these infections in ICU patients. Also, ICU patients should be prescribed appropriate antibiotics to prevent respiratory infections. </span></span></span> Nosocomial Infection, Respiratory tract, Intensive care unit 129 134 http://jommid.pasteur.ac.ir/browse.php?a_code=A-10-196-3&slc_lang=en&sid=1 Mahshid Saeedi mahshidsaeedi2015@gmail.com 0000-0003-3916-2026 No Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran Leila Fozouni lili_kia@yahoo.com 0000-0002-2248-0354 Yes Department of Microbiology, Gorgan Branch, Islamic Azad University, Gorgan, Iran