Use of WalkAway MicroScan system colistin well when determining the susceptibility of Pseudomonas aeruginosa and Acinetobacter baumannii recent clinical isolates

Colistin resistance screening by 3 μg/ml colistin agar in Carbapenemase‐producing Enterobacterales

“…Moreover, automated methods are not recommended due to the great variability and error when it comes to assess susceptibility of this particular antibiotic. 10 , 11 In 2020, the Clinical Laboratory Standard Institute (CLSI) approved two methods to perform colistin resistance (CR) surveillance tests, broth disk elution and colistin agar test based in modified agar dilution method, which consist in the use of serial dilutions between 1 and 4 μg/ml, and finally, colistin broth microdilution (BMD), which is still considered the reference method. 12 These methodologies require specific reagents including the agar media containing different colistin concentrations, posing difficulties to implement these tests as routine techniques in every microbiological laboratory.…”

“…The size of the colistin molecule does not allow for its use with the classical disc diffusion method nor diffusion by concentration gradient. Moreover, automated methods are not recommended due to the great variability and error when it comes to assess susceptibility of this particular antibiotic 10,11 . In 2020, the Clinical Laboratory Standard Institute (CLSI) approved two methods to perform colistin resistance (CR) surveillance tests, broth disk elution and colistin agar test based in modified agar dilution method, which consist in the use of serial dilutions between 1 and 4 μg/ml, and finally, colistin broth microdilution (BMD), which is still considered the reference method 12 .…”

Urinary tract infection by Acinetobacter dijkshoorniae and good clinical response to treatment

“…En cuanto a la sensibilidad antibiótica, según nuestros resultados, se trató de un aislado clínico bastante sensible a los antibióticos, a diferencia de A. baumannii . En base a lo cual, creemos que las especies de Acinetobacter con perfil de resistencia escaso pueden ser nuevas especies, como la descrita aquí u otras aún no descritas, que presentan menos resistencias que los A. baumannii descritos hasta la fecha [ 6 , 7 ]. De ahí la gran utilidad e importancia del uso del MALDI-TOF para la identificación correcta de las especies del complejo Acinetobacter .…”