Original article / research
Year : 2026 Month : January Volume : 15 Issue : 1 Page : MO16 - MO19 Full Version

Evaluation of Carba NP for Rapid Detection of Carbapenem Resistance in Routine Diagnostic Laboratories: A Retrospective Validation Study
Parijat Das, Kumar Anand Shrutiraaj, Nidhi Pandey
1. Clinical Microbiologist, Department of Microbiology, AFMC, Pune, Maharashtra, India. 2. Medical Specialist, Department of Medicine, AFMC, Pune, Maharashtra, India. 3. PhD, Department of Microbiology, IMS, BHU, Varanasi, Uttar Pradesh, India.
 
Correspondence Address :
Parijat Das,
AFMC Old Sholapur Road, Near Race Course, Pune, Maharashtra, India.
E-mail: parijat5628@gmail.com
 
ABSTRACT
: Introduction: Resistance to carbapenems is a major concern for clinicians and infection control practitioners. Fast and simple detection methods are essential to protect our increasingly limited arsenal of antibiotics. A rapid biochemical method for detecting carbapenemase production has recently been proposed, namely the Carbapenemase Nordmann-Poirel test (Carba NP test), which is based on detecting hydrolysis of the β-lactam ring of imipenem.

Aim: The aim of the present study was to assess the performance of the RAPIDEC® Carba NP test.

Materials and Methods: The present retrospective validation study was conducted in the Department of Microbiology, Armed Forces Medical College (AFMC), Pune, India between January and April 2018. A total of 159 isolates, retrospectively collected from various specimens from patients admitted to the Intensive Care Unit (ICU) between January 2016 and December 2017, were included in the study. These isolates had previously been characterised as either carbapenemase producers (n=109) or non-producers (n=50), based on meropenem disc susceptibility testing and the presence or absence of carbapenemase genes. The carbapenemase genes screened included Klebsiella pneumoniae carbapenemase (KPC), New Delhi Metallo-β-lactamase-1 (NDM-1), Oxacillinase-48 (OXA-48), Imipenemase (IMP), and Verona Integron-encoded Metallo-β-lactamase (VIM), using Polymerase Chain Reaction (PCR) assays. The RAPIDEC® CARBA NP test was performed and interpreted according to the manufacturer’s instructions to phenotypically detect carbapenemase production based on imipenem hydrolysis. Sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of RAPIDEC® CARBA NP were calculated using a 2×2 contingency table, taking PCR as the gold standard. Microsoft Excel was used for data analysis.

Results: Among the 109 carbapenemase producers, the RAPIDEC® CARBA NP test was positive in 106 cases and negative in 3 cases. All 50 carbapenemase non-producers were negative by the assay. RAPIDEC® CARBA NP demonstrated a sensitivity of 97.25% {95% Confidence Interval (CI): 92.17%-99.43%}, specificity of 100% (95% CI: 92.89%-100.00%), PPV of 100% (95% CI: 96.58%-100.00%), and NPV of 94.34% (95% CI: 84.52%-98.07%).

Conclusion: The RAPIDEC® CARBA NP test is simple, easy to interpret, and cost-effective, providing a practical solution for early detection of carbapenemase-producing Gram-negative bacteria in microbiological laboratories, and is helpful in infection prevention and control measures.
Keywords : Antimicrobial stewardship, Carbapenemase Nordmann-Poirel test, Gram negative bacteria, Infection, Multidrug resistant organisms
DOI and Others : DOI: 10.7860/NJLM/2026/79688.2954 Date of Submission: Apr 03, 2025 Date of Peer Review: Jul 15, 2025 Date of Acceptance: Oct 21, 2025 Date of Publishing: Jan 01, 2026 AUTHOR DECLARATION: • Financial or Other Competing Interests: None • Was Ethics Committee Approval obtained for this study? Yes • Was informed consent obtained from the subjects involved in the study? NA • For any images presented appropriate consent has been obtained from the subjects. Yes PLAGIARISM CHECKING METHODS: • Plagiarism X-checker: May 02, 2025 • Manual Googling: Oct 16, 2025 • iThenticate Software: Oct 20, 2025 (15%) ETYMOLOGY: Author Origin EMENDATIONS: 6
 
TABLES AND FIGURES