This study aims to determine the clinical characteristics, risk factors, and resistance mechanisms of patients with carbapenem-resistant P. mirabilis bacteremia.Patients with P. mirabilis growth in blood culture samples sent to bacteriology laboratory between 2018 and 2021 were retrospectively analyzed. Patients meeting the inclusion criteria were divided into carbapenem-resistant and carbapenem- susceptible groups. The investigators recorded demographic data, clinical features, and laboratory findings. Resistance genes were investigated in carbapenem-resistant isolates using PCR.

Patients with P. mirabilis growth in blood culture who met the study criteria were divided into two groups as carbapenem susceptible and resistant according to carbapenem antibiogram results. Patients with carbapenem-resistant P. mirabilis (CRPM) growth in blood culture were included in the case group and patients with carbapenem- susceptible P. mirabilis (CSPM) growth in blood culture were included in the control group.

Demographic characteristics of the patients, concomitant chronic diseases, Charlson comorbidity index (CCI), hospital and intensive care unit (ICU) hospitalization and number of days in the last year, history and type of invasive intervention in the last three months (surgical-invasive), history of antibiotic use in the last three months and types of antibiotics used (Penicillin, cephalosporin, quinolone, carbapenem, tigecycline, colistin, aminoglycoside), hospitalization unit, total length of hospitalization, sample collection unit, growth result and antibiogram, clinical and laboratory data of the day of growth, sepsis and septic shock evaluated according to systemic inflammatory response syndrome (SIRS) criteria, 30-day mortality and patient outcome information were recorded.

Carbapenemase-producing gene regions were investigated by Polymerase Chain Reaction (PCR) in accessible samples of patients with carbapenem-resistant P. mirabilis growth in blood cultures.

Inclusion Criteria:

• Inpatients aged 18 years and older
• P. mirabilis growth in blood cultures

Exclusion Criteria:

• Samples taken in emergency departments, outpatient clinics, day treatment units
• Recurrent growths of the same patient

. Inpatients aged 18 years and older with P. mirabilis growth in blood cultures were included in the study, while samples taken in emergency departments, outpatient clinics, day treatment units and recurrent growths of the same patient were excluded.