Comparison of Respiratory Microbiota in Patients with and Without Hospital-Acquired Infection

Background: Nosocomial infections have increased among patients admitted to the intensive care unit (ICU). Objectives: This study investigated the microbiota pattern of the respiratory system in hospitalized patients with treatment-resistant respiratory infections compared to those without treatment-resistant respiratory infections. Methods: This case-control study utilized sputum samples from hospital-acquired infection (HAI) and non-HAI (NHAI) patients over 52 years old hospitalized in the ICU. Identification and determination of the drug sensitivity of the bacteria responsible for treatment-resistant respiratory infections were made by culture method in selective and differential media and VITEK 2 device. Finally, quantitative polymerase chain reaction (qPCR) was used to analyze the microbiota of the respiratory system. Results: Excessive prescription of antibiotics, long hospitalization, and history of surgery were important risk factors for nosocomial infections. The study of antibiotic resistance of pathogens causing hospital infections indicated their high resistance to most common antibiotics. Also, nosocomial infections led to a change in lung microbiota in HAI patients. The frequencies of Streptococcus pyogenes, S. pneumoniae, and Haemophilus influenzae were higher in patients with treatment-resistant respiratory infection (P < 0.05), but the frequency of Neisseria spp. was higher in patients without treatment-resistant respiratory infection (P < 0.05). Conclusions: The pathogens responsible for nosocomial infections had acquired resistance to a wide range of antibiotics, leading to changes in their respiratory microbiota.