etiology of severe acute respiratory infections in icu-admitted patients during the covid-19 pandemic in iran: a single center study

Background: acute respiratory infections (ari) caused by a wide range of etiologies represent a significant public health challenge worldwide.objectives: in this study, we aimed to evaluate the characteristics of ari caused by various respiratory pathogens among patients admitted to intensive care units (icus) in a referral hospital in iran during the first four waves of the severe acute respiratory syndrome coronavirus 2 (sars-cov-2) pandemic. methods: a total of 395 patients with ari were enrolled, all hospitalized in the icus of nemazi teaching hospital, affiliated with shiraz university of medical sciences in shiraz, iran, over a 13-month period from april 2020 to june 2021. real-time polymerase chain reaction (rt-pcr) assays were used to detect sars-cov-2, influenza viruses, respiratory syncytial virus (rsv), mycoplasma, and chlamydiain nasopharyngeal fluid (nps) samples. the demographic and clinical data, including underlying diseases, were also considered. results: of the 395 patients, 209 (53.7%) were male, and the mean age was 32 ± 27 years. an etiology was detected in 63 (16%) patients, with 53 testing positive for sars-cov-2 and 5 each for chlamydiaand mycoplasma. no rsv or influenza infections were detected. the highest rate of covid-19 was observed among adults aged 36 to 65 years (5.31%), while the lowest rate was in children under 5 years old (0.3%). shortness of breath was the most common symptom in sars-cov-2-infected patients (p-value ≤ 0.001). of the total patients, 146 (37%) had at least one underlying disease, with diabetes being the most common (8.1%). conclusions: the absence of rsv and influenza infections, along with a notable number of chlamydiaand mycoplasma infections during the first four waves of the sars-cov-2 pandemic, emphasizes the importance of continuous surveillance of the etiologies of ari during respiratory pandemics. this information is critical for guiding appropriate infection control measures and selecting empirical antibiotic regimens.