Retrospective Cohort Study of Tracheal Etiological Agents and their Drug Resistance in Patients Referred to Imam Khomeini Hospital in Ardabil City from 2012 to 2022

Endotracheal tube-associated infections, an important cause of mortality in patients admitted to Intensive Care Units (ICU), are mainly caused by opportunistic, Multidrug-Resistant (MDR) bacteria. Accurate diagnosis of etiological agents and investigation of their antibiotic resistance patterns could improve the clinical management of these patients. This study, conducted over 11 years, aimed to examine the epidemiological changes of bacteria and the trends in drug resistance at a referral medical center in the northwest of Iran by analyzing endotracheal culture data.

In this retrospective cohort study, tracheal swab samples were collected from patients referred to Imam Khomeini Hospital in Ardabil, from 2012 to 2022. The samples were cultured on appropriate culture media, including blood agar, chocolate agar, and McConkie agar, to provide conditions for bacterial growth. After incubation for 24 to 48 hours, bacterial colonies were identified using microscopic and chemical methods. The antibiotic susceptibility patterns of the isolated bacteria were determined using the disk diffusion method. All data were analyzed with SPSS software version 25.

In total, 598 samples examined were positive for endotracheal tube-related infections. Following Acinetobacter spp. (n = 204 [34.1%]), Acinetobacter baumannii (n = 148 [24.7%]) and Klebsiella spp. (n = 78 [13%]) were the most prevalent bacteria isolated. The majority (87.6%) of isolated bacteria were MDR, and most bacteria were isolated from the ICU. Ceftazidime was more common than gentamicin.

Acinetobacter spp. and Klebsiella spp. are the most important infectious agents found in the tracheal cultures of hospitalized patients. The elevated levels of antibiotic resistance are a serious challenge in hospital settings. Gentamicin was identified as one of the most effective drugs against the aforesaid isolates.

The study’s findings highlight the necessity of strengthening infection control programs, in addition to critically evaluating antibiotic use and establishing treatment protocols based on regional data.