Risk factors for multidrug-resistant organism infections in patients with lower respiratory tract infections: a systematic review and meta-analysis

Multidrug-resistant organism (MDRO) infections are a leading cause of poor prognosis in patients with lower respiratory tract infections (LRTIs), yet systematic evaluation of relevant risk factors remains insufficient. This study aimed to systematically assess potential factors associated with MDRO infection among patients diagnosed with LRTIs. PubMed, Web of Science, the Cochrane Library, Embase and Scopus were systematically searched from inception to 1 March 2026. English-language observational studies reporting associations between antibiotic exposure, comorbidities, invasive procedures or related clinical factors and MDRO infection risk were included. Odds ratios (ORs) were pooled using random-effects models, with subgroup, sensitivity and publication-bias analyses performed. The review protocol was registered(INPLASY202680075), and the manuscript was reported in accordance with the PRISMA 2020 statement. Twenty studies were included. Antibiotic exposure may be associated with increased MDRO infection risk (OR = 4.39, 95% confidence interval [CI]: 2.50–7.71, I² = 89.9%); subgroup analysis revealed significant associations for exposure within 30 days (OR = 1.38, 95% CI: 0.85–1.90, I² = 0%) and 90 days (OR = 0.87, 95% CI: 0.54–1.20, I² = 0%). Nine studies did not clearly report the time window of antibiotic exposure and were therefore interpreted narratively rather than as a distinct clinical subgroup. Comorbidities may be associated with MDRO infection risk (OR = 2.69, 95% CI: 2.21–3.27, I² = 1.2%), with neurological disorders/stroke showing the highest risk (OR = 3.16, 95% CI: 1.74–5.73). Invasive procedures may be associated with MDRO infection risk (OR = 7.33, 95% CI: 3.46–15.52, I² = 82.7%), with reoperation demonstrating particularly high risk (OR = 13.49, 95% CI: 6.42–28.36). Antibiotic exposure, comorbidities and invasive procedures may serve as potential factors associated with MDRO infections in patients with LRTIs. Clinical decision-making should integrate recent antibiotic exposure history, baseline comorbidity status, invasive procedure exposure and previous MDRO colonisation or infection, when available, to support stratified management strategies.