Non-Aeruginosa Pseudomonas Species Isolated from Bacteremia Patients at a Tertiary Care Center in India: A Retrospective Study

Human infection with non-aeruginosa Pseudomonas (NAP) is not commonly observed but can be severe and associated with significant morbidity and mortality. The aim for the present study was to investigate the prevalence, patient characteristics, risk factors, and clinical presentation of patients with NAP bacteremia. Additionally, the antibiotic sensitivity patterns of NAP isolates were assessed. The current retrospective study was conducted in the microbiology laboratory of a tertiary care center from January 2022 to October 2024. Two sets of blood cultures were received in BACTEC bottles (Becton, Dickinson and Company, Franklin Lakes, NJ) and were incubated. The blood samples were cultured on blood and MacConkey agar, and microscopy was performed using Gram staining. Species identification was performed via matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Antibiotic sensitivity testing was performed using meropenem, colistin, levofloxacin, amikacin, piperacillin-tazobactam, imipenem, aztreonam, ceftazidime, and cefoperazone-sulbactam. During the 2-year study period, 42 blood cultures grew Pseudomonas species other than Pseudomonas aeruginosa. The majority of patients were <60 years of age (76.1%). The age range of the population was 4-75 years. The male-to-female ratio of the population was 1.1:1. In this study, most isolates belonged to Pseudomonas mosselii (n = 13; 31%), followed by Pseudomonas stutzeri (n = 11; 26.1%), Pseudomonas putida (n = 9; 21.4%), Pseudomonas fluorescens (n = 5; 11.9%), and Pseudomonasalcaligenes (n = 3; 7.1%). The most common risk factors were the presence of a central venous catheter (n = 34; 81%) and mechanical ventilation (n = 25; 59.5%). Among the Pseudomonas mosellii isolates, the highest resistance was observed to meropenem (70%), imipenem (70%), and ceftazidime (70%). Timely diagnosis and treatment can help in reducing mortality and morbidity among NAP bacteremia patients.