Clinico-Microbiological Profile of Carbapenem-Resistant Acinetobacter baumannii Isolates From Intensive Care Unit Patients and In Vitro Activity of Sulbactam-Durlobactam: A Cross-Sectional Study From Eastern India

TL;DR

This study examines carbapenem-resistant Acinetobacter baumannii in ICU patients in India and finds that a new drug combination, sulbactam-durlobactam, is effective against most of these resistant strains.

Contribution

The study is one of the first to evaluate the in vitro efficacy of sulbactam-durlobactam against CRAB isolates in Eastern India.

Findings

94.5% of Acinetobacter isolates were A. baumannii, with 82.5% being carbapenem-resistant.

98.6% of CRAB isolates were sensitive to sulbactam-durlobactam.

CRAB infections were strongly associated with comorbidities and had a 40% mortality rate.

Abstract

Background

Carbapenem-resistant Acinetobacter baumannii (CRAB) causes severe infections in intensive care units (ICUs), with increased morbidity and mortality. The pathogen exhibits extensive antimicrobial resistance, substantially limiting available therapeutic options. Recently, the emergence of sulbactam-durlobactam, a novel β-lactam/β-lactamase inhibitor combination, has renewed interest as a potential treatment option. The study evaluates the clinical and microbiological profile of CRAB isolates, assesses the in vitro efficacy of sulbactam-durlobactam in these isolates, and analyzes key risk factors and clinical outcomes in patients developing CRAB infection.

Methodology

This cross-sectional study was conducted over a period of six months (July-December 2024) at a tertiary care hospital in Odisha. All clinical specimens were processed for bacterial identification and antimicrobial susceptibility testing using the VITEK-2 automated system (bioMérieux, Marcy-l’Étoile, France). A. baumannii isolates were characterized as CRAB and carbapenem-susceptible Acinetobacter baumannii (CSAB). CRAB susceptibility to sulbactam-durlobactam was tested by the Kirby-Bauer disc diffusion method, and results were interpreted based on the Clinical & Laboratory Standards Institute 2024 guidelines. Clinical and microbiological data were analyzed by applying appropriate statistical tests, with a p-value <0.05 considered statistically significant.

Results

Among 291 Acinetobacter spp. isolates, 275 (94.5%) were A. baumannii, and out of the 275 A. baumannii, 227 (82.5%) were carbapenem-resistant. Most of the CRAB-infected patients were ≥60 years old (93, 40.9%). All CRAB isolates were multidrug resistant. CRAB cases showed a significantly higher association with multiple comorbidities and risk factors, including hypertension (53.7%, 122/227), diabetes (31.1%, 72/227), malignancy (22.9%, 52/227), renal disease (33.4%, 76/227), surgery/invasive procedures/accident (33.9%, 77/227), lung disease (53.7%, 122/227), liver disease (31.2%, 71/227), bloodstream infection (57.2%, 130/227), and genitourinary infection (61.6%, 140/227) than CSAB cases. Mortality was 40% (91/227) in CRAB. The majority (98.6%, 224/227) of the CRAB isolates showed sensitivity to sulbactam-durlobactam.

Conclusions

Our study highlights the alarming rise of CRAB in a tertiary care setting in Odisha as an emerging ICU pathogen, particularly among elderly patients. The strong association with comorbidities, risk factors, and multidrug resistance underscores the need for continuous surveillance and targeted interventions. Sulbactam-durlobactam demonstrated promising activity, indicating its potential as an effective therapeutic option.

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