A Prospective Study on Clinical Profile, Anti Microbial Susceptibility and Treatment Outcome of Less Common Non Lactose Fermenting Gram Negative Bacilli in ICU

INTRODUCTION: Non-lactose fermenting Gram-negative bacilli (NLFGNB) account for approximately 15% of Gram-negative bacteria isolated from clinical specimens. While these organisms are typically of low virulence, they exhibit significant antimicrobial resistance and are frequently implicated in hospital-acquired infections. They serve as opportunistic pathogens in patients who are vulnerable due to factors such as prolonged antibiotic use, immunosuppressive treatments, steroid therapy, advanced age, chronic illnesses, indwelling medical devices, prolonged hospital stays, and mechanical ventilation. While Acinetobacter and Pseudomonas species are well-documented, less common NLFGNBs, such as Stenotrophomonas maltophilia, Burkholderia cepacia, Elizabethkingia meningoseptica, Achromobacter, and Chryseobacterium, are increasingly reported. However, data on these less common pathogens remain limited. OBJECTIVES: This study aims to evaluate the prevalence of less common NLFGNB infections, assess patient clinical profiles, examine antimicrobial susceptibility patterns, and analyze treatment outcomes in ICU patients affected by these organisms. MATERIALS AND METHODS: This prospective observational study was conducted over 18 months at Royal Care Super Speciality Hospital, which houses a 30-bed multidisciplinary ICU, after obtaining the necessary ethics committee approval. The study included clinical samples from blood, endotracheal (ET) secretions, urine, pus from wounds, bronchoalveolar lavage (BAL), and cerebrospinal fluid (CSF). Patient demographic data, including age, comorbidities, antimicrobial exposure, infection sources, immunosuppressive treatments, antimicrobial susceptibility patterns, and treatment outcomes (ICU survival and 30-day mortality), were collected and analyzed. RESULTS: Of the 4,292 clinical samples analyzed, NLFGNB were identified in 479 samples, accounting for 11.2% of the total. Among these, 41 samples (8.5%) represented less common NLFGNB. The most frequently isolated organisms were Stenotrophomonas maltophilia (46.3%), followed by Burkholderia spp. (31.7%). and Elizabethkingia spp. (21.9%) Positive cultures were predominantly obtained from ET secretions (75.6%), followed by blood (12.1%), urine (9.75%), and pus (2.43%). Demographic analysis showed that 85% of patients were male, with a mean age of 54 years. Prior steroid exposure was noted in 36.5% of patients, and 78% had received treatment with high-end antibiotics, including polymyxin, ceftazidime-avibactam, and meropenem. Comorbidities were present in 68% of patients, with diabetes, hypertension, coronary artery disease (CAD), and chronic kidney disease (CKD) being the most common. Hemodynamic instability was observed in 46% of patients, with 36.5% developing acute kidney injury (AKI). Regarding outcomes, the 30-day mortality rate was 12.1%, however the NLFGNB infection alone could not be attributable to observed mortality. Additionally, three patients were lost to follow-up due to discharge against medical advice (AMA). DISCUSSION: Although less common, NLFGNB exhibit a remarkable ability to persist and thrive in the hospital environment. Our study underscores their significant association with comorbidities, prior exposure to high-end antibiotics, and frequent steroid use, all of which likely predispose patients to these infections. Moreover, the observed mortality rates highlight the urgent need for robust antimicrobial stewardship programs, prudent optimization of steroid therapy, and vigilant monitoring of high-risk patients to mitigate the clinical and healthcare impact of these pathogens.