scholarly journals Complete ciprofloxacin resistance in gonococcal isolates in an urban Ugandan clinic: findings from a cross-sectional study

2018 ◽  
Vol 30 (3) ◽  
pp. 256-263 ◽  
Author(s):  
Emily Mabonga ◽  
Rosalind Parkes-Ratanshi ◽  
Stefan Riedel ◽  
Sheila Nabweyambo ◽  
Olive Mbabazi ◽  
...  
Keyword(s):  
Sex Workers ◽  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Outpatient Service ◽  
Tetracycline Resistance ◽  
Disk Diffusion ◽  
Reference Laboratory ◽  
Transmitted Infection ◽  
Cross Sectional ◽  
Agar Dilution

Antimicrobial resistance (AMR) to gonorrhoea is a threat to global health security. There have been concerns expressed that countries with high rates of disease have poor surveillance. The objectives of the study were to determine the AMR patterns of Neisseria gonorrhoeae clinical isolates to antimicrobial agents in patients with HIV or high risk of HIV acquisition, to compare the concordance of disk diffusion and agar dilution as methods for determining AMR to N. gonorrhoeae, and to describe methodological challenges to carrying out AMR testing. The study was conducted at an HIV outpatient service for at-risk populations and an outreach clinic for commercial sex workers in Kampala. Patients were offered a sexually transmitted infection screen using a polymerase chain reaction (PCR)-based assay. Samples positive for gonorrhoea were cultured. Antimicrobial susceptibility testing was performed using disk diffusion and isolates were sent to a reference laboratory for agar dilution direct susceptibility testing. Five hundred and seventy-five patients were screened. There were 33 (5.7%) patients with gonorrhoea detected by PCR. Of the 16 viable N. gonorrhoeae isolates, 100% were resistant to ciprofloxacin and tetracycline by disk diffusion and 31% exhibited reduced susceptibility to ceftriaxone and cefixime. By agar dilution, 100% of isolates were resistant to ciprofloxacin and all isolates were susceptible to ceftriaxone and cefixime. There was concordance between disk diffusion and agar dilution for ciprofloxacin and tetracycline resistance and a significant discordance for third-generation cephalosporins. More than half the women with gonorrhoea were asymptomatic and represent a potential reservoir for ongoing transmission. AMR testing of N. gonorrhoeae isolates is needed to ensure optimal treatment and prevention of antibiotic resistance progression.

scholarly journals Comparative Analysis of Gradient Diffusion and Disk Diffusion with Agar Dilution for Susceptibility Testing of Elizabethkingia anophelis

Antibiotics ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 450
Author(s):  
Chien-Tung Chiu ◽  
Chung-Hsu Lai ◽  
Yi-Han Huang ◽  
Chih-Hui Yang ◽  
Jiun-Nong Lin
Keyword(s):  
Antimicrobial Agents ◽  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Gradient Diffusion ◽  
Minimum Requirements ◽  
Agar Dilution

Elizabethkingia anophelis has recently emerged as a cause of life-threatening infections. This study compared the results of antimicrobial susceptibility testing (AST) conducted for E. anophelis through different methods. E. anophelis isolates collected between January 2005 and June 2019 were examined for their susceptibility to 14 antimicrobial agents by using disk diffusion, gradient diffusion (Etest; (bioMérieux S.A., Marcy l’Etoile, France), and agar dilution methods. The agar dilution method was the reference assay. According to the agar dilution method, the isolates exhibited the highest susceptibility to minocycline (100%), doxycycline (97.6%), rifampin (95.2%), and levofloxacin (78.6%). A very major error rate of >1.5% was observed for nine antibiotics tested using the disk diffusion method. The overall categorical agreement rate between the disk diffusion and agar dilution methods was 74.8%, and ceftazidime, minocycline, levofloxacin, and rifampin met the minimum requirements for discrepancy and agreement rates. The Etest method tended to produce lower log2 minimum inhibitory concentrations for the antibiotics, except for trimethoprim–sulfamethoxazole and rifampin; the method resulted in very major errors for nine antibiotics. The overall essential and categorical agreement rates between the Etest and agar dilution methods were 67.3% and 76.1%, respectively. The Etest method demonstrated acceptable discrepancy and agreement rates for ceftazidime, minocycline, doxycycline, levofloxacin, and rifampin. AST results obtained through the disk diffusion and Etest methods for multiple antibiotics differed significantly from those obtained using the agar dilution method. These two assays should not be a routine alternative for AST for E. anophelis.

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.

scholarly journals Interpretive criteria for testing susceptibility of staphylococci to mupirocin.

1997 ◽  
Vol 41 (5) ◽  
pp. 1137-1139 ◽  
Author(s):  
J E Finlay ◽  
L A Miller ◽  
J A Poupard
Keyword(s):  
Reliable Method ◽  
Susceptibility Testing ◽  
Error Rates ◽  
Disk Diffusion ◽  
Zone Diameter ◽  
Testing Susceptibility ◽  
Agar Dilution

To determine appropriate mupirocin susceptibility testing interpretive criteria, 177 staphylococci were tested by agar dilution, disk diffusion, and E test. E test was found to be a reliable method for determining susceptibility of staphylococci to mupirocin. The agar dilution and disk diffusion results were plotted on a scattergram, and error rates were calculated. No errors were found with susceptibility breakpoints of > or = 4 microg/ml (MIC) and > or = 14 mm (zone diameter).

scholarly journals Comparison of methods for the determination of antimicrobial resistance in Campylobacter spp. human and the food chain isolates

2008 ◽  
Vol 52 (No. 4) ◽  
pp. 169-174
Author(s):  
M. Holasova ◽  
R. Karpiskova ◽  
S. Karpiskova ◽  
V. Babak ◽  
J. Schlegelova
Keyword(s):  
Nalidixic Acid ◽  
Antimicrobial Agents ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Microdilution Method ◽  
Study Results ◽  
Agar Dilution

With a microdilution method, using the commercial diagnostic test Sensititre Susceptibility Plates for Campylobacter MIC (Trek Diagnostic Systems, Cleveland, OH, USA), disk diffusion and agar dilution method, resistance to six antimicrobial agents were examined in a reference strain <i>Campylobacter jejuni</i> ATCC 33560 and 73 thermo-tolerant isolates of <i>Campylobacter</i> spp. For the microdilution method and all tested antimicrobial agents, our determined values of microbiological breakpoints of resistant strains were suggested as the minimum inhibitory concentration (MIC<sub>R</sub>) for ciprofloxacin &ge; 0.5, erythromycin &ge; 4, gentamicin &ge; 4, nalidixic acid &ge; 32 and tetracycline &ge; 4 &mu;g/ml. On the basis of our study results, strains resistant to clindamycin were MIC<sub>R</sub> &ge; 2 &mu;g/ml for the dilution methods and a zone diameter R ≤ 16 mm for the disk diffusion method. Comparison of the results of the resistance examination, a microdilution method and disk diffusion method with the reference agar dilution method, showed that all compared methods yielded identical results with the exception of the resistance determination in erythromycin and nalidixic acid. The errors were mostly the result of the interpretation criteria for MIC<sub>R</sub> of agar dilution method and different conditions of cultivation used. However, the compared methods, provide results comparable with the reference method having greater convenience of measurement.

scholarly journals Variation in erythromycin and clindamycin susceptibilities of Streptococcus pneumoniae by four test methods.

1997 ◽  
Vol 41 (1) ◽  
pp. 129-134 ◽  
Author(s):  
E L Fasola ◽  
S Bajaksouzian ◽  
P C Appelbaum ◽  
M R Jacobs
Keyword(s):  
Streptococcus Pneumoniae ◽  
Susceptibility Testing ◽  
Ambient Air ◽  
Test Methods ◽  
Disk Diffusion ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution ◽  
Resistant Strains

Susceptibilities of 124 strains of Streptococcus pneumoniae to erythromycin and clindamycin were determined by the National Committee for the Clinical Laboratory Standards (NCCLS) broth microdilution method, with incubation for 20 to 24 h in ambient air and with modifications of this method by incubation for up to 48 h in air and CO2. Strains were also tested by agar dilution, E-test, and disk diffusion; good correlation was obtained with these methods, with clear separation into bimodal populations of susceptible and resistant stains. The broth microdilution method, however, using incubation in air for 24 h (NCCLS method), misclassified 4 of 92 erythromycin-resistant strains (1 as susceptible and 3 as intermediate) and 25 of 58 clindamycin-resistant strains (all as susceptible). With the exception of one strain with clindamycin, susceptible and resistant strains were correctly classified by the microdilution method with incubation in CO2 for 24 h or in ambient air for 48 h. Disk diffusion, agar dilution, and E-test methods with incubation in 5% CO2 are therefore reliable methods for susceptibility testing of pneumococci against these agents. However, the NCCLS microdilution method, which specifies incubation for 20 to 24 h in ambient air, produced significant very major errors (43%) clindamycin. Modification of the microdilution method by incubation in 5% CO2 or by extension of incubation time in ambient air to 48 h corrected these errors. Disk diffusion, however, was shown to be a simple, convenient, and reliable method for susceptibility testing of pneumococci to erythromycin and clindamycin and is suggested as the method of choice for these agents.

scholarly journals Inaccuracy of the Disk Diffusion Method Compared with the Agar Dilution Method for Susceptibility Testing of Campylobacter spp.

2011 ◽  
Vol 50 (1) ◽  
pp. 52-56 ◽  
Author(s):  
Mirva Lehtopolku ◽  
Pirkko Kotilainen ◽  
Pauli Puukka ◽  
Ulla-Maija Nakari ◽  
Anja Siitonen ◽  
...  
Keyword(s):  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Diffusion Method ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Disk Diffusion Method ◽  
Agar Dilution ◽  
Campylobacter Spp

Gonococcal resistance: evolving from penicillin, tetracycline to the quinolones in South Africa – implications for treatment guidelines

2007 ◽  
Vol 18 (10) ◽  
pp. 697-699 ◽  
Author(s):  
Mari De Jongh ◽  
Yusuf Dangor ◽  
Anvir Adam ◽  
Anwar A Hoosen
Keyword(s):  
South Africa ◽  
Antimicrobial Agents ◽  
Treatment Guidelines ◽  
Tetracycline Resistance ◽  
Sexually Transmitted ◽  
Antimicrobial Susceptibility Profile ◽  
Resistance To Penicillin ◽  
Agar Dilution ◽  
High Level ◽  
First Time

Resistant Neisseria gonorrhoeae has been evolving. This study assessed the antimicrobial susceptibility profile of isolates in the Pretoria region, South Africa. Isolates of N. gonorrhoeae from men with urethritis were tested for susceptibility to eight antimicrobial agents by disc diffusion, Etest and agar dilution methods. Chromosomal resistance to penicillin was found in 16% of isolates, 16% showed plasmid-mediated resistance and decreased susceptibility was seen in 73% of isolates. For the first time, there is evidence of high-level tetracycline resistance (36%). Ciprofloxacin resistance emerged at 7%. All isolates remained susceptible to ceftriaxone. In view of these findings of the emergence of quinolone-resistant N. gonorrhoeae, national treatment guidelines for syndromic management of sexually transmitted infections need to be urgently reviewed. The injectable preparation, ceftriaxone has to be considered as a first-line agent for the management of gonococcal infections. Overall, the gonococcal isolates in the Pretoria region remain susceptible to ceftriaxone, cefoxitin, cefpodoxime and spectinomycin.

scholarly journals In VitroActivity of Fosfomycin against a Collection of Clinical Pseudomonas aeruginosa Isolates from 16 Spanish Hospitals: Establishing the Validity of Standard Broth Microdilution as Susceptibility Testing Method

2013 ◽  
Vol 57 (11) ◽  
pp. 5701-5703 ◽  
Author(s):  
María Díez-Aguilar ◽  
María-Isabel Morosini ◽  
Rosa del Campo ◽  
María García-Castillo ◽  
Javier Zamora ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Susceptibility Testing ◽  
Disk Diffusion ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution ◽  
Content Type ◽  
Testing Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

ABSTRACTThe broth microdilution method for fosfomycin andPseudomonas aeruginosawas assessed and compared with the approved agar dilution method in 206 genetically unrelatedP. aeruginosaclinical isolates. Essential agreement between the two methods was 84%, and categorical agreement was 89.3%. Additionally, Etest and disk diffusion assays were performed. Results validate broth microdilution as a reliable susceptibility testing method for fosfomycin againstP. aeruginosa. Conversely, unacceptable concordance was established between Etest and disk diffusion results with agar dilution results.

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