Antibiotic Resistance Patterns and Correlation with Clinical Outcomes in Adult Patients with Nosocomial and Community-acquired Infections in a Critical Care Unit of a Tertiary Care Hospital in Kolkata, India

OBJECTIVES: Nosocomial infections caused by multidrug-resistant (MDR) bacteria are major contributors to morbidity and mortality among patients in critical care units (CCUs) worldwide. Antibiotic resistance has become a significant concern in the treatment of these infections, particularly in comparison to community-acquired infections. This study aims to investigate the complex relationship between antibiotic resistance patterns of pathogens responsible for infections in adult CCU patients at a tertiary care hospital in Kolkata, India, and various factors such as treatment types, clinical attributes, and other relevant variables. MATERIALS AND METHODS: This retrospective study was conducted from February 2022 to March 2023, involving 260 adult patients admitted to the CCU with infections. Infections that were manifested within 48 hours of CCU admission were regarded as community- acquired, whereas if manifestation was observed after 48 hours, the infections were regarded as nosocomial. The culture and sensitivity patterns of clinical isolates were analyzed from blood, urine, sputum, endotracheal tube (ET) aspirates, stool, skin swabs, ascitic fluid, throat swabs, and central line catheter insertion site swabs. A total of 382 specimens were collected from infected adult CCU patients. A correlation study examined the relationship between patient clinical data, outcomes, and the infectious organisms responsible for nosocomial and community-acquired infections. Similar data were collected in the year 2015 to 2017 from the same critical care unit. A comparison of AMR pattern will be done. RESULTS: Salient features observed in this study are as follows. Infected patients were predominantly male (53.46%) compared to female patients (46.92%). The average age of the patients was 61.96±16.40 years, with male patients (63.88±14.74) being significantly older than female patients (59.80±17.85) (p<0.05). Survival rates were significantly lower in older patients and those with longer CCU and hospital stays. Survival was positively associated with steroid use, no device usage, and the absence of MDR organisms. Acinetobacter baumannii (47%) and Klebsiella pneumoniae (31%) were the predominant MDR organisms. Nosocomial infections accounted for 77% of cases, while 18% were community-acquired infections (CA), and 5% were CA infections that later became nosocomial. Mortality was significantly higher in nosocomial infections (˜49%) compared to CA infections (˜8%) and CA infections that later became nosocomial (˜25%). Susceptibility of patients with comorbidities such as T2DM, COPD, and CKD to nosocomial infections (˜70%) and CA infections (˜71%) were similar, but lower in CA-nosocomial patients (50%). MDR A. baumannii was the most common pathogen in nosocomial infections (˜24%), followed by MDR K. pneumoniae (˜16%), Escherichia coli (˜10%), and MDR Pseudomonas aeruginosa (˜7%). In CA infections, E. coli (˜22%), Candida albicans (˜13%), and Staphylococcus haemolyticus (˜11%) were most prevalent. Significant differences in AMR were noted from 2015 to 2017 in comparison to the recent study. DISCUSSION/CONCLUSION: MDR nosocomial infections are increasingly common in adult CCU patients, leading to higher mortality rates and significant therapeutic challenges. Regular surveillance of antimicrobial resistance patterns is crucial for effective antibiotic stewardship and mitigating MDR pathogens’ harmful effects in critically ill patients. Complex relations between organisms, AMR and host-related issues are key factors in the mortality and morbidity of patients. Trends in change in antimicrobial resistance over time can guide us to take measures to prevent AMR.