Comparison of Conventional Methods and Automated Systems for Determining Antibiotic Susceptibility of Bacteria Isolated from Urine Culture

Abstract

Objective: The aim of our study was to compare the results obtained from different methods, which are used to determine the susceptibility to antimicrobials, and to determine the agreement between them.
 Materials and Methods: A total of 397 strains consisting of 329 gram negative and 68 gram positive bacteria that were isolated from urine samples and identification and antibiogram of which were performed by automated systems, were included in the study. The results obtained from broth microdilution, E test, VITEK and disk diffusion were compared.
 Results: Our antimicrobial susceptibility test results in gram negative bacteria showed a categorical agreement of 93.3% with a very major error rate of 1.5 in disk diffusion test, while a categorical agreement of 90% with a very major error rate of 2.2% in Vitek 2 test. The agreement for E test was 95.3% with a very major error rate of 1.1. In the antimicrobial susceptibility test of gram positive bacteria, the rate of agreement for disk diffusion, E test and Vitek 2 was 97.2%, 98.4% and 95.4% respectively. Very major error rate was found % 1.5 ve % 2.6 in disk diffusion and Vitek 2, respectively, while no very major error was found in E test.
 Conclusions: In conclusion, our data suggest that disk diffusion test, Vitek 2 system and E test test are accurate and acceptable for antibiotic susceptibility tests of gram positive bacteria. The agreement rate of BMD and E test methods was found above 90% for all antibiotics, and it was reached a conclusion that the susceptibility results of gram negative bacteria for ceftriaxone and nitrofurantoin obtained from VITEK; the susceptibility results of disk diffusion test for ceftriaxone and ciprofloxacin should be confirmed by a more reliable method.
 Bangladesh Journal of Medical Science Vol.18(3) 2019 p.519-526

Comparison of Carbapenem Resistance Detected by the BD Phoenix Automated System in Enterobacteriaceae Isolates with E-Test Method

“…This rate is higher, especially for ertapenem [23]. In a study which comparing the antibiotic susceptibility of bacteria isolated from urine culture with conventional methods and automated systems has shown that agreement for E-test was 95.3% with a very major error rate of 1.1 [24]. In a study comparing meropenem MICs and susceptibility with various tests in Carbapenem-resistant K. pneumonia strains; E-test demonstrated 82.6% agreement with broth microdilution MICs, a very major error rate of 2.2%, and a minor error rate of 2.2% and Vitek 2 automated system MIC agreement was 30.4%, with a 23.9% very major error rate and a 39.1% minor error rate [25].…”

Anticorrosive and Microbial Inhibition Performance of a Coating Loaded with Andrographis paniculata on Stainless Steel in Seawater

“…The turbidity of the sample was measured by a UV−Vis spectrophotometer at the 550-nm wavelength. The bacterial suspension was diluted to obtain a reading of 0.125, equivalent to 0.5 McFarland turbidity [ 39 ]. Antibacterial activities of the coatings and of each primary component were evaluated using the well diffusion method.…”

Molecular typing of multidrug resistant bacteria isolated from health care professionals’ mobile phone: A pilot study in Jashore, Bangladesh

“…A study showed disk diffusion method, compared to automated systems, had significant efficiency in determination of antibiotic susceptibility of gram-negative and gram-positive bacteria. 23 For Gram-negative bacteria 19 different types of antibiotics from 9 classes were cast-off for the study: β-lactamases (Ampicillin-10 µg, Aztreonam-30 µg, Amoxicillin-Clavulanic acid-30 µg, Amoxicillin-30 µg), Carbapenem (Imepenem-10 µg, Meropenem-10 µg), Aminoglycosides (Streptomycin-10 µg, Kanamycin-5 µg, Gentamycin-10 µg, Amikacin-30 µg), Fluroquinolone (Levofloxacin-5 µg, Ciprofloxacin-5 µg), Phenicol (Chloramphenicol-30 µg), Tetracycline (Tetracycline-30 µg), Cotrimoxazole (Co-trimoxazole-25 µg), Cephalosporin (Cefepime-30 µg, ceftazidime-30 µg, Cefotaxime-30 µg), Macrolid (Azithromycin-10 µg) whereas for Gram-positive bacteria 18 different types of antibiotics from 8 classes were selected for the study: β-lactamases (Penicillin-10 µg, Ampicillin-10 µg, Oxacillin-30 µg, Amoxicillin-Clavulanic acid-30 µg), Carbapenem (Imepenem-10 µg, Meropenem-10 µg), Aminoglycosides (Gentamycin-10 µg), Fluroquinolone (Levofloxacin-5 µg, Norfloxacin-10 µg, Ciprofloxacin-5 µg), Cephalosporin (Cefotaxime-30 µg, Cefepime-30 µg, ceftazidime-30 µg), Tetracycline (Tetracycline-30 µg), Macrolid (Erythromycine-15 µg, Lincomycin-2 µg, Clindamycin-2 µg), Phenicol (Chloramphenicol-30 µg) against gram positive Staphylococcus spp.. Mueller-Hinton agar plate was used for antimicrobial susceptibility test (AST) and incubated at 37˚C for 18-24 hours and measured the inhibition zone diameters (IZDs). The IZDs were recorded according to the CLSI standard antibiotic breakpoints and interpreted as susceptible, intermediate and resistant.…”