Evaluation of the rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test for rapid colistin resistance detection in lactose non-fermenting Gram-negative bacteria

Abstract

INTRODUCTION : Colistin is one of the last-resort antibiotics for treating multidrug-resistant (MDR) or extensively drug-resistant (XDR) lactose non-fermenting Gram-negative bacteria such as Pseudomonas aeruginosa and Acinetobacter baumannii.

GAP STATEMENT : As the rate of colistin resistance is steadily rising, there is a need for rapid and accurate antimicrobial susceptibility testing methods for colistin. The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test has recently been developed for rapid detection of colistin resistance in P. aeruginosa and A. baumannii.

AIM : The present study aimed to evaluate the performance of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test in comparison with the reference broth microdilution (BMD) method.

METHODOLOGY : The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test was performed using a total of 135 P. aeruginosa (17 colistin-resistant and 118 colistin-susceptible) and 66 A. baumannii isolates (32 colistin-resistant and 34 colistin-susceptible), in comparison with the reference BMD method.

RESULTS : The categorical agreement of the Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test with the reference BMD method was 97.5 % with a major error rate of 0 % (0/152) and a very major error (VME) rate of 10.2 %. The VME rate was higher (23.5 %) when calculated separately for P. aeruginosa isolates. The overall sensitivity and specificity were 89.8 and 100 %, respectively.

CONCLUSION : The Rapid ResaPolymyxin Acinetobacter/Pseudomonas NP test performed better for A. baumannii than for P. aeruginosa.