Development of the optimal procedure for increasing HbA1c concentration in control materials for external quality assessment

Original Research

Abstract

Background: The research aimed to increase certain HbA1c concentrations at medical decision levels for external quality control samples from healthy donor blood.

Methods: The in vitro study was performed from October 2019 to January 2021 at Quality Control Center for Medical Laboratory at University of Medicine and Pharmacy at Ho Chi Minh City. The study observed on the conditions including the optimal buffer solutions (BAGPM, BPS, Ringer, Saline), temperature (2ºC - 8ºC, 22ºC - 24ºC, 37ºC), and glucose concentration (100 mM, 305 mM, 500 mM) affecting the HbA1c concentration in vitro to make the external quality control samples fell in normal, prediabetes, and diabetes range. At every condition, the HbA1c concentration was measured by Tina Quant method to look for the optimal procedure to increase HbA1c concentration required of the external quality control protocol.

Results: The highest HbA1c concentration (11.57±0.2%) was found in BAGPM solution with 100 mM glucose after 15 days with the baseline HbA1c 5.43±0.13%; the HbA1c level increase dramatically at 37ºC in BAGPM 500 mM glucose solution in fifteen days (40.03±1.05%).

Conclusions: The appropriate conditions were identified to prepare HbA1c standards for prediabetic and diabetic levels. The standards for HbA1c concentrations were recommended to prepare by incubating RBCs from non-diabetic donor blood in BAGPM solution containing glucose at 37ºC for 24 hours. Glucose concentrations should be 100 mM and 500 mM, respectively, for prediabetic level (HbA1c ~ 6.0 ± 0.12%) and diabetic level (HbA1c ~ 9.6 ± 0.17%).

Graphical abstract

Phenotypic prevalence of resistance to carbapenems, colistin and genes encoding carbapenemase in Pseudomonas aeruginosa

Original Research

Abstract

Introduction: The production of carbapenem enzyme is one of the most frequent mechanisms reported in cabapenem resistant Pseudomonas aeruginosa. Besides, a growing number of mobile colistin resistance (MCR) genes are threatening the renewed interest of colistin as a "last-resort" against carbapenem-resistant pathogens. Therefore, the detection of carbapenem-resistant and colistin-resistant phenotypes as well as preventing transmission of multi-resistant P. aeruginosa strains with genes coding for carbapenemase is extremely necessary.

Material and methods: Among 159 P. aeruginosa strains were collected 46 isolates, which is resistant or intermediated to meropenem. Modified carbapenem inactivation (mCIM) and colistin broth disk elution (CBDE) methods were used to identify carbapenemase-producing strains and colistin resistance. In addition, a multiplex real-time PCR technique was applied to investigate the frequency of emergence of carbapenem resistance genes.

Results: The results revealed that 25 strains (54.3%) were positive with mCIM test and none of them resistant to colistin by CBDE method. Number of strains carrying a gene blaIMP: 4 strains (16%), blaNDM: 2 strains (8%). Strains are carrying two genes: blaIMP + blaNDM: 10 strains (40%), blaVIM + blaNDM: 1 strain (4%), blaNDM + blaOXA-48: 1 strain (4%) and are carrying three genes blaIMP + blaNDM + blaOXA-48: 6 strains (24%), blaKPC + blaIMP + blaNDM: 1 strain (4%).

Conclusions: All mCIM positive P. aeruginosa were contained carbapenemase genes. Colistin still reserved a good effect to combine with other antibiotics in multi-resistant treatment. Hence, the classification of genes can help clinicians selected appropriate antibiotics so that more effective treatment for patients.

Graphical abstract

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