Diagnostic Accuracy of the Simplified Carbapenem Inactivation Method versus the Modified Hodge Test in Carbapenem-Resistant Pseudomonas aeruginosa: A Cross-Sectional Study

Fara Nayo  Faramarisa; Kristiawan Basuki  Rahmat; Berliana Nisfa  Laily; Eddy Bagus  Wasito; Kuntaman

doi:10.37275/oaijmr.v6i4.924

Authors

Fara Nayo Faramarisa Master Program of Clinical Medicine, Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia/Faculty of Medicine, University of Darussalam Gontor, Ponorogo, Indonesia
Kristiawan Basuki Rahmat Faculty of Medicine, University of Darussalam Gontor, Ponorogo, Indonesia
Berliana Nisfa Laily Faculty of Medicine, University of Darussalam Gontor, Ponorogo, Indonesia
Eddy Bagus Wasito Department of Medical Microbiology, Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia
Kuntaman Department of Medical Microbiology, Faculty of Medicine, Universitas Airlangga, Surabaya, Indonesia

DOI:

https://doi.org/10.37275/oaijmr.v6i4.924

Keywords:

Carbapenem-resistant Pseudomonas aeruginosa, Carbapenemase, Modified Hodge Test, Sensitivity and specificity

Abstract

Background: Carbapenem-resistant Pseudomonas aeruginosa (CRPA) is among the pathogens contributing most to the global burden of antimicrobial resistance, and its pooled prevalence in Indonesia reaches 43%. Carbapenem resistance and carbapenemase production are not equivalent, and only the enzymatic route is transmissible and therapeutically decisive. Molecular confirmation is unavailable in most Indonesian laboratories, so an accurate low-cost phenotypic assay is needed.

Objective: To compare the simplified carbapenem inactivation method (sCIM) with the Modified Hodge Test (MHT) for detecting carbapenemase production in carbapenem-resistant P. aeruginosa.

Methods: This cross-sectional diagnostic-accuracy study evaluated 30 meropenem- and imipenem-resistant clinical isolates archived at Dr. Soetomo General Academic Hospital, Surabaya, using PCR for blaIMP, blaGES, blaOXA, blaNDM, blaKPC and blaVIM as the reference standard.

Result: A carbapenemase gene was detected in 13/30 isolates (43.3%): blaIMP in 9, blaGES in 3 and blaOXA in 1. sCIM achieved 92.31% sensitivity (95% confidence interval 64.0-99.8), 100.00% specificity (80.5-100.0), 96.7% accuracy and near-perfect agreement with PCR (kappa 0.932). MHT achieved 46.15% sensitivity (19.2-74.9), 88.24% specificity (63.6-98.5) and fair agreement (kappa 0.360). The paired exact McNemar test confirmed the sensitivity advantage of sCIM (p = 0.031), and bootstrapping showed a 26.6-percentage-point difference in overall accuracy (95% confidence interval 10.0-43.3). MHT detected no blaGES-positive isolate and only 6/9 blaIMP-positive isolates; sCIM detected all of both, while neither assay detected the single poorly expressed blaOXA isolate.

Conclusion: sCIM is an accurate, rapid and inexpensive assay that should replace MHT in Indonesian laboratories and feed directly into stewardship and infection-control decisions.