Evaluation of Polymicrobial Pulmonary Infections during Five Years at a Tertiary Hospital in Mashhad, Eastern Iran

Background: Lung infection is a global health problem associated with high morbidity and mortality world-wide and increasing rates of hospitalization. Polymicrobial Pleuropulmonary infection is define as the simultaneous isolations of two or more other organisms from lung secretions culture which are associated with increased infection severity outcome compared to monomicrobial Pleuropulmonary infections. The aim of this study is evaluation of polymicrobial pulmonary infection rate during March 2019 to February 2024 at a Tertiary Hospital in Mashhad, Eastern Iran. Methods: This single-center retrospective study was conducted from March 2019 to February 2024 in Shahid Kamyab Hospital, Mashhad, Iran. Our data in this study included 429 patients with pulmonary infection in the five years studied, which 34 patients were under 18 years old and 395 patients were over 18 years old. The total number of positive lung samples of these patients was 532. In this study, we investigated the prevalence of polymicrobial lung infections along with the bacteria that cause them. Results: A total of 532 positive lung culture specimens were included, which 196 cases were polymicrobial (36.8 %) and 336 cases were monomicrobial (63.2 %). this study showed that Acinetobacter baumannii had the most frequency among other bacteria which cause polymicrobial pulmonary infections (32 %). Conclusion: Pulmonary infection is a serious complication, which significantly increases mortality rate and medical costs(1). In this retrospective study we have found that polymicrobial pulmonary infections in patients in this hospital was 36.8 % that Acinetobacter baumannii was the most cause of infections.