Doctors from the Department of Microbiology at BJ Medical College (BJMC) have developed a new and faster method to determine the susceptibility of colistin, a powerful “last-resort” antibiotic used to treat patients suffering from multi-drug resistant (MDR) infections.
A Breakthrough in Antibiotic Testing
The new testing approach not only reduces turnaround time but also improves accuracy, ensuring that colistin is prescribed only to patients who are likely to benefit from it. Given colistin’s known nephrotoxic effects, doctors must confirm its effectiveness against the infection before use to avoid severe kidney damage and other complications.
Limitations of the Traditional Method
Until now, broth microdilution (BMD) has been considered the gold standard for testing colistin susceptibility. However, the process is labor-intensive, time-consuming, and often impractical for routine use in busy or resource-limited laboratories.
Introducing the Colistin Broth Disk Elution (CBDE) Method
According to Dr. Rajesh Karyakarte, Head of the Microbiology Department at BJMC and the study’s corresponding author, the newly tested colistin broth disk elution (CBDE) method demonstrated high categorical agreement with BMD results and low error rates. “Given its simplicity, cost-effectiveness, and reproducibility, CBDE can serve as a practical alternative for antimicrobial susceptibility testing, especially in resource-constrained settings,” he said.
Saving Time and Improving Accuracy
Dr. Karyakarte explained that the CBDE method could save up to an hour per patient while providing more reliable results. “This innovative method allows rapid assessment of colistin susceptibility in high-risk ICU patients with severe infections. Despite its neurotoxic potential, colistin often becomes the only available treatment option for intensivists. With CBDE, we can assess susceptibility without the need for dilution, saving time and manpower — both crucial in government hospital settings,” he noted.
Published Findings and Future Policy Implications
As reported by TOI, the findings were published in the peer-reviewed journal Cureus on September 8 under the title “Comparison of Broth Disk Elution and Broth Microdilution Methods for Colistin Susceptibility Testing in Carbapenem-Resistant Enterobacteriaceae and Pseudomonas aeruginosa.”
Dr. Karyakarte added that the study has been submitted to the Ministry of Health and Family Welfare for review. It is also being considered for potential policy adoption. “The CBDE method still requires further validation, but once approved, it could replace the existing BMD method for colistin susceptibility testing,” he said.
Towards Smarter Antimicrobial Stewardship
If validated and adopted nationally, the CBDE method could revolutionize how hospitals test for antibiotic susceptibility. It holds the potential to enhance antimicrobial stewardship and reduce misuse of last-resort antibiotics. This, in turn, can improve patient outcomes in the fight against resistant infections.