Akademik Veri Yönetim Sistemi
31st ECCMID, Basel, İsviçre, 9 - 12 Temmuz 2021, ss.0-1
The isolation of colistin-resistant
bacteria from bloodstream has increased for few years, causing therapy failure.
It is recommended to use colistin in combination in infections caused by these
bacteria. Broth microdiution method is the recommended as a standard method to
detect colistin resistance. However this method could not be used in routin
laboratories since it is labor-intensive and time consuming; therefore the requirement
for new easy methods has emerged.
In this study, susceptibility to
colistin of MDR-GNB was studied by macrodilution, disc elution, commercial microdilution, rapid polymyxin NP tests and compared to broth
microdiution to evaluate detecting of colistin resistance in MDR-GNB (n=102)
isolated from blood cultures sent from different wards in 2019-2020. The
combination of colistin with tigecycline and meropenem were then tested by
checkerboard method. Additionally mcr-1 gene was investigated by
PCR in colistin resistant isolates.
Resistance to colistin was found to be 15%,
MİK50 and MİK90 were found to be ≤0.25 μg/ml and 16
μg/ml
by BMD method. The categorical agreement was very well (100%) in four
methods no very major errors. However macrodilution and
commerical microdilution (Diagonistics 8011) methods showed the highest minor
errors rates amongst the four methods. The best essential agreement rate was
detected by disc elution method. Colistin-meropenem combination
exhibited 100% synergism and colistin-tigecycline 80%. No mcr-1 genes
were detected in colistin resistant isolates.
In conclusion, disc elution and HPNP which
those newly developed methods for detecting resistance to colistin were the
easiest, cheapest, most efficient and best performing methods, so they are convenient
to use in routine laboratory. Colistin-meropenem combination is thought to be
an excellent choice to treat bacteremia/sepsis caused by colistin-resistant
bacteria.