scholarly journals Comparison of Disk Diffusion and E-Test with the Reference Method of Microbroth Dilution for Susceptibility Testing of Acinetobacter baumannii Isolates to Tetracyclines

2016 ◽  
Vol 10 (1) ◽  
pp. 44-49
Author(s):  
Abdollah Ardebili ◽  
Malihe Talebi ◽  
Abdolaziz Rastegar Lari ◽  
◽  
◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Disk Diffusion ◽  
Microbroth Dilution

scholarly journals Pseudo-Outbreak of Imipenem-Resistant Acinetobacter baumannii Resulting from False Susceptibility Testing by a Rapid Automated System

2000 ◽  
Vol 38 (9) ◽  
pp. 3505-3507 ◽  
Author(s):  
Athanassios Tsakris ◽  
Anastassia Pantazi ◽  
Spyros Pournaras ◽  
Antonios Maniatis ◽  
Aleka Polyzou ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
General Hospital ◽  
Susceptibility Testing ◽  
Homogeneous Group ◽  
Susceptibility Test ◽  
Automated System ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
High Prevalence ◽  
Agar Dilution

Introduction of the Vitek GNS-506 susceptibility testing cards in the Hippokration General Hospital, Thessaloniki, Greece, resulted in an apparently high prevalence of imipenem-resistant Acinetobacter baumannii. When 35 of these isolates were further tested by disk diffusion, broth microdilution, and agar dilution assays, 32 were imipenem sensitive by all tests and three were sensitive or intermediate, depending on the method. The pseudoresistant acinetobacters did not form a genetically homogeneous group. It is suggested that the detection of imipenem-resistant A. baumannii isolates by this system should be confirmed by an additional susceptibility test.

scholarly journals Comparative Evaluation of Colistin Susceptibility Testing Methods among Carbapenem-Nonsusceptible Klebsiella pneumoniae and Acinetobacter baumannii Clinical Isolates

2015 ◽  
Vol 59 (8) ◽  
pp. 4625-4630 ◽  
Author(s):  
Konstantina Dafopoulou ◽  
Olympia Zarkotou ◽  
Evangelia Dimitroulia ◽  
Christos Hadjichristodoulou ◽  
Vasiliki Gennimata ◽  
...  
Keyword(s):  
Klebsiella Pneumoniae ◽  
Acinetobacter Baumannii ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Test Strip ◽  
Clinical Isolates ◽  
Content Type ◽  
Gradient Diffusion ◽  
Agar Dilution ◽  
Resistant Strains

ABSTRACTWe compared six colistin susceptibility testing (ST) methods on 61 carbapenem-nonsusceptibleKlebsiella pneumoniae(n= 41) andAcinetobacter baumannii(n= 20) clinical isolates with provisionally elevated colistin MICs by routine ST. Colistin MICs were determined by broth microdilution (BMD), BMD with 0.002% polysorbate 80 (P80) (BMD-P80), agar dilution (AD), Etest, Vitek2, and MIC test strip (MTS). BMD was used as the reference method for comparison. The EUCAST-recommended susceptible and resistant breakpoints of ≤2 and >2 μg/ml, respectively, were applied for bothK. pneumoniaeandA. baumannii. The proportions of colistin-resistant strains were 95.1, 77, 96.7, 57.4, 65.6, and 98.4% by BMD, BMD-P80, AD, Etest, MTS, and Vitek2, respectively. The Etest and MTS methods produced excessive rates of very major errors (VMEs) (39.3 and 31.1%, respectively), while BMD-P80 produced 18% VMEs, AD produced 3.3% VMEs, and Vitek2 produced no VMEs. Major errors (MEs) were rather limited by all tested methods. These data show that gradient diffusion methods may lead to inappropriate colistin therapy. Clinical laboratories should consider the use of automated systems, such as Vitek2, or dilution methods for colistin ST.

scholarly journals Carbapenem Susceptibility Testing Errors Using Three Automated Systems, Disk Diffusion, Etest, and Broth Microdilution and Carbapenem Resistance Genes in Isolates of Acinetobacter baumannii-calcoaceticus Complex

2011 ◽  
Vol 55 (10) ◽  
pp. 4707-4711 ◽  
Author(s):  
Ana Elizabeth Markelz ◽  
Katrin Mende ◽  
Clinton K. Murray ◽  
Xin Yu ◽  
Wendy C. Zera ◽  
...  
Keyword(s):  
Acinetobacter Baumannii ◽  
Resistance Genes ◽  
Dna Sequences ◽  
Susceptibility Testing ◽  
Carbapenem Resistance ◽  
Disk Diffusion ◽  
Resistance Testing ◽  
Broth Microdilution ◽  
Carbapenemase Gene ◽  
Automated Methods

ABSTRACTTheAcinetobacter baumannii-calcoaceticuscomplex (ABC) is associated with increasing carbapenem resistance, necessitating accurate resistance testing to maximize therapeutic options. We determined the accuracy of carbapenem antimicrobial susceptibility tests for ABC isolates and surveyed them for genetic determinants of carbapenem resistance. A total of 107 single-patient ABC isolates from blood and wound infections from 2006 to 2008 were evaluated. MICs of imipenem, meropenem, and doripenem determined by broth microdilution (BMD) were compared to results obtained by disk diffusion, Etest, and automated methods (the MicroScan, Phoenix, and Vitek 2 systems). Discordant results were categorized as very major errors (VME), major errors (ME), and minor errors (mE). DNA sequences encoding OXA beta-lactamase enzymes (blaOXA-23-like,blaOXA-24-like,blaOXA-58-like, andblaOXA-51-like) and metallo-β-lactamases (MBLs) (IMP, VIM, and SIM1) were identified by PCR, as was theKPC2carbapenemase gene. Imipenem was more active than meropenem and doripenem. The percentage of susceptibility was 37.4% for imipenem, 35.5% for meropenem, and 3.7% for doripenem. Manual methods were more accurate than automated methods.blaOXA-23-likeandblaOXA-24-likewere the primary resistance genes found.blaOXA-58-like, MBLs, andKPC2were not present. Both automated testing and manual testing for susceptibility to doripenem were very inaccurate, with VME rates ranging between 2.8 and 30.8%. International variability in carbapenem breakpoints and the absence of CLSI breakpoints for doripenem present a challenge in susceptibility testing.

scholarly journals Triazole susceptibility of Aspergillus species: environmental survey in Lagos, Nigeria and review of the rest of Africa

2021 ◽  
Vol 8 ◽  
pp. 204993612110443
Author(s):  
Cynthia Abosede Campbell ◽  
Iriagbonse Iyabo Osaigbovo ◽  
Rita Okeoghene Oladele
Keyword(s):  
Aspergillus Terreus ◽  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Aspergillus Species ◽  
Environmental Isolates ◽  
The Subject ◽  
Microbroth Dilution ◽  
Testing Reference ◽  
Isolated Species

Background: Triazole resistance is an emerging problem in the management of human aspergillosis globally and can arise in Aspergillus species which have been exposed to azole fungicides in the environment. We surveyed local government and council development areas in Lagos, Nigeria, to determine the distribution of Aspergillus species in the environment and their susceptibility to locally available triazole antifungal agents. We also reviewed the literature on the subject from the rest of Africa. Methods: A total of 168 soil samples from six locations in Lagos, Nigeria were processed and cultured on Saboraud dextrose agar impregnated with chloramphenicol to isolate Aspergillus species. Isolates were tested for susceptibility to itraconazole and voriconazole by microbroth dilution according to the European Committee on Antimicrobial Susceptibility Testing reference method. Relevant databases were searched to identify published work pertaining to triazole susceptibility of Aspergillus species in Africa. Results: A total of 117 Aspergillus species were isolated. Aspergillus niger was the most frequently isolated species (42.7%). Other species isolated were Aspergillus flavus, 37 (31.6%), Aspergillus terreus, 20 (17.1%), Aspergillus fumigatus, 5 (4.3%) and Aspergillus nidulans, 5 (4.3%). All isolates were susceptible to itraconazole and voriconazole. The literature review showed documented evidence of triazole-resistant Aspergillus species from East and West Africa. Conclusions: We found no triazole resistance in environmental isolates of Aspergillus in Lagos, Nigeria. Nevertheless, regular surveillance in clinical and environmental isolates is necessary in the light of findings from other African studies.

scholarly journals Correlation between E-Test, Disk Diffusion, and Microdilution Methods for Antifungal Susceptibility Testing of Fluconazole and Voriconazole

2003 ◽  
Vol 47 (5) ◽  
pp. 1647-1651 ◽  
Author(s):  
Madonna J. Matar ◽  
Luis Ostrosky-Zeichner ◽  
Victor L. Paetznick ◽  
Jose R. Rodriguez ◽  
Enuo Chen ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Clinical Laboratory ◽  
Antifungal Susceptibility ◽  
Reference Method ◽  
Antifungal Susceptibility Testing ◽  
Disk Diffusion ◽  
National Committee ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Test Disk

ABSTRACT The activities of fluconazole and voriconazole against isolates of Candida spp. (n = 400) were tested by the E-test, disk diffusion, and the National Committee for Clinical Laboratory Standards (NCCLS) M27-A2 broth microdilution-based reference methods. More than 96% of isolates found to be susceptible to fluconazole by the reference method were identified as susceptible by the agar-based methods. Lesser degrees of correlation with the reference method were seen for isolates identified as resistant by the agar-based methods. Interpretive categories are not available for voriconazole, but results qualitatively similar to those for fluconazole were seen. The agar-based E-test and disk diffusion methods are reliable alternatives to the NCCLS M27-A2 reference microdilution method for isolates that test susceptible to fluconazole.

scholarly journals A Simplified Method for Testing Bordetella pertussisfor Resistance to Erythromycin and Other Antimicrobial Agents

2000 ◽  
Vol 38 (3) ◽  
pp. 1151-1155 ◽  
Author(s):  
Bertha C. Hill ◽  
Carolyn N. Baker ◽  
Fred C. Tenover
Keyword(s):  
Antimicrobial Susceptibility ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Reference Method ◽  
Antimicrobial Susceptibility Testing ◽  
Disk Diffusion ◽  
Mueller Hinton ◽  
Disk Diffusion Testing ◽  
Direct Inoculation ◽  
Agar Dilution

Present methods of antimicrobial susceptibility testing ofBordetella pertussis are time consuming and require specialized media that are not commercially available. We tested 52 isolates of B. pertussis for resistance to erythromycin, trimethoprim-sulfamethoxazole, chloramphenicol, and rifampin by agar dilution with Bordet-Gengou agar (BGA) containing 20% horse blood (reference method), Etest using BGA and Regan-Lowe agar without cephalexin (RL−C), and disk diffusion using BGA and RL−C. The organisms tested included four erythromycin-resistant isolates ofB. pertussis from a single patient, a second erythromycin-resistant strain of B. pertussis from an unrelated patient in another state, and 47 nasopharyngeal surveillance isolates of B. pertussis from children in the western United States. The results of agar dilution testing using direct inoculation of the organisms suspended in Mueller-Hinton broth were within ±1 dilution of those obtained after overnight passage of the inoculum in Stainer-Scholte medium, which is the traditional method of testing B. pertussis. The Etest method produced MICs similar to those of the agar dilution reference method for three of the four antimicrobial agents tested; the trimethoprim-sulfamethoxazole results were lower with Etest, particularly when the direct suspension method was used. Most of the Etest MICs, except for that of erythromycin, were on scale. Disk diffusion testing using RL−C medium was helpful in identifying the erythromycin-resistant strains, which produced no zone of inhibition around the disk; susceptible isolates produced zones of at least 42 mm. Thus, the antimicrobial susceptibility testing of B. pertussis can be simplified by using the Etest or disk diffusion on RL−C to screen for erythromycin-resistant isolates of B. pertussis.

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