scholarly journals Antibiotic Susceptibility Pattern ofMycobacterium marinum

2000 ◽  
Vol 44 (11) ◽  
pp. 3133-3136 ◽  
Author(s):  
Alexandra Aubry ◽  
Vincent Jarlier ◽  
Sylvie Escolano ◽  
Chantal Truffot-Pernot ◽  
Emmanuelle Cambau
Keyword(s):  
Antibiotic Susceptibility ◽  
Geometric Mean ◽  
Multidrug Resistant ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Susceptibility Pattern ◽  
Cutaneous Infections ◽  
Agar Dilution

ABSTRACT In vitro activities of 17 antibiotics against 53 clinical strains of Mycobacterium marinum, an atypical mycobacterium responsible for cutaneous infections, were determined using the reference agar dilution method. Rifampin and rifabutin were the most active drugs (MICs at which 90% of the isolates tested were inhibited [MIC90s], 0.5 and 0.6 μg/ml, respectively). MICs of minocycline (MIC90, 4 μg/ml), doxycycline (MIC90, 16 μg/ml), clarithromycin (MIC90, 4 μg/ml), sparfloxacin (MIC90, 2 μg/ml), moxifloxacin (MIC90, 1 μg/ml), imipenem (MIC90, 8 μg/ml), sulfamethoxazole (MIC90, 8 μg/ml) and amikacin (MIC90, 4 μg/ml) were close to the susceptibility breakpoints. MICs of isoniazid, ethambutol, trimethoprim, azithromycin, ciprofloxacin, ofloxacin, and levofloxacin were above the concentrations usually obtained in vivo. For each drug, the MIC50, geometric mean MIC, and modal MIC were very close, showing that all the strains had a similar susceptibility pattern. Percent agreement (within ±1 log2 dilution) between MICs yielded by the Etest method and by the agar dilution method used as reference were 83, 59, 43, and 24% for minocycline, rifampin, clarithromycin, and sparfloxacin, respectively. Reproducibility with the Etest was low, in contrast to that with the agar dilution method. In conclusion, M. marinum is a naturally multidrug-resistant species for which the agar dilution method is more accurate than the Etest for antibiotic susceptibility testing.

scholarly journals In vitro efficacy of gentamicin against multidrug-resistant Neisseria gonorrhoeae: synergy of three gentamicin antimicrobial combinations

2021 ◽  
Author(s):  
Xuechun Li ◽  
Wenjing Le ◽  
Xiangdi Lou ◽  
Biwei Wang ◽  
Caroline A. Genco ◽  
...  
Keyword(s):  
Inhibitory Concentration ◽  
Geometric Mean ◽  
Multidrug Resistant ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Fractional Inhibitory Concentration ◽  
Agar Dilution ◽  
Resistant Strains ◽  
Antimicrobial Combinations

ABSTRACTObjectivesTo determine in vitro activities of gentamicin alone and in combination with ceftriaxone, ertapenem and azithromycin against multidrug-resistant (MDR) N. gonorrhoeae isolates.Methods407 isolates from Nanjing, China, obtained in 2016 and 2017, had minimum inhibitory concentrations (MICs) determined for gentamicin using the agar dilution method. Antimicrobial combinations were also tested in 97 MDR strains using the antimicrobial gradient epsilometer test (Etest); results ranging from synergy to antagonism were interpreted using the fractional inhibitory concentration (FICI).ResultsAll 407 gonococcal isolates were susceptible to gentamicin. MICs ranged from 2 mg/L to 16 mg/L. Synergy was demonstrated in 16.5%(16/97), 27.8%(27/97) and 8.2%(8/97) MDR strains when gentamicin was combined with ceftriaxone [geometric mean (GM) FICI; 0.747], ertapenem (GM FICI; 0.662) and azithromycin (GM FICI; 1.021), respectively. No antimicrobial antagonism was observed with any combination. The three antimicrobial combinations were indifferent overall. The overall GM MICs of gentamicin were reduced by 2.63-, 3.80- and 1.98-fold when tested in combination with ceftriaxone, ertapenem and azithromycin, respectively. The GM MICs of the three antimicrobials by themselves were reduced by 3-, 2.57- and 1.98-fold respectively, when each was tested in combination with gentamicin. No antimicrobial antagonism was observed with any combination.ConclusionsGentamicin alone was effective in vitro against MDR N. gonorrhoeae and in combination with ceftriaxone, ertapenem or azithromycin. Combination testing of resistant strains, overall, showed lower effective MICs against gentamicin itself and each of the three antimicrobials when used in combination with gentamicin.

An improved susceptibility test based on Amberlite reveals the potential antilisterial activity of fosfomycin in vitro

2013 ◽  
Vol 59 (4) ◽  
pp. 252-259 ◽  
Author(s):  
Lei Han ◽  
Jin'e Lei ◽  
Shaoshan Han ◽  
Li He ◽  
Chaofeng Ma ◽  
...  
Keyword(s):  
Brain Heart Infusion ◽  
Susceptibility Test ◽  
Host Cells ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Broth Microdilution Method ◽  
Agar Dilution

Listeria monocytogenes is resistant to fosfomycin in vitro but is susceptible in vivo due to increased expression of positive regulator factor A (PrfA) and its dependent factor, hexose phosphate transporter (Hpt), upon infection of host cells. Amberlite, a polymeric adsorbent resin, could induce PrfA-dependent gene expression and thus, in theory, improve the sensitivity of L. monocytogenes to fosfomycin in vitro. In the current study, an improved susceptibility test based on Amberlite was developed using reference strains. Thirty-five clinical isolates were further examined to verify those preliminary results. Briefly, Amberlite increased in vitro fosfomycin sensitivity of all strains. Optimal Amberlite concentrations, as evaluated through the expression of phospholipase B (PlcB) and Hpt, were 10% and 15% (w/v) in agar media and 3% (w/v) in broth media. Mueller–Hinton (MH) medium, tryptone soya (TS) medium, and brain heart infusion (BHI) medium were used to verify the results in the control strains using agar dilution and broth micro- and macro-dilution methods. Better listerial growth was shown in TS and BHI than in MH. Both broth dilution methods yielded lower minimal inhibitory concentration (MIC) of fosfomycin than the agar dilution method. The MIC of fosfomycin for 35 clinical isolates was 2–32 μg/mL, suggesting improved susceptibility. In conclusion, in vitro sensitivity of L. monocytogenes to fosfomycin was substantially improved in the presence of 3% Amberlite-supplemented TSB or BHIB and the broth microdilution method. This improved method revealed the potential antilisterial activity of fosfomycin in vitro and could facilitate the therapy of listeriosis using fosfomycin.

scholarly journals In Vitro and In Vivo Evaluations of β-Lactam/β-Lactamase Mono- and Combined Therapies against Carbapenem-Nonsusceptible Enterobacteriaceae in Taiwan

2020 ◽  
Vol 8 (12) ◽  
pp. 1981
Author(s):  
Tsung-Ying Yang ◽  
Ya-Ju Hsieh ◽  
Li-Ting Kao ◽  
Guan-Hong Liu ◽  
Shao-Hsuan Lian ◽  
...  
Keyword(s):  
Carbapenem Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Geographic Variations ◽  
C Elegans ◽  
Agar Dilution ◽  
Antibiotic Susceptibility Patterns ◽  
Resistance Rates

Increasing carbapenem resistance rates worldwide underscored the urgent need of novel antimicrobials. Ceftazidime–avibactam and aztreonam–avibactam combinations are developed to combat carbapenem resistance, but biological and geographic variations must be considered for antibiotic susceptibility patterns varied. Thus, we sought to assess the susceptibilities of ceftazidime–avibactam and aztreonam–avibactam against 660 carbapenem-nonsusceptible Enterobacteriaceae isolates (472 Klebsiella pneumoniae and 188 Escherichia coli) collected during an earlier Taiwan surveillance study. Agar dilution method was used to determine ceftazidime–avibactam and aztreonam–avibactam susceptibility. Metallo-carbapenemase’s contribution to resistance were investigated with EDTA addition. The in vivo efficacies were evaluated using a Caenorhabditis elegans model. High susceptibility rates were observed for ceftazidime–avibactam and aztreonam–avibactam against the 472 carbapenem-nonsusceptible K. pneumoniae (CnsKP) (85.2% and 95.3%, respectively) and 188 carbapenem-nonsusceptible E. coli (CnsEC) isolates (91.5% and 94.1%, respectively). For non-metallo-carbapenemase producers, the susceptibility rates for ceftazidime–avibactam were 93.6% for CnsKP and 97.7% for CnsEC, whereas only 7.1% CnsKP and 11.1% CnsEC in metallo-carbapenemase producers were susceptible to ceftazidime–avibactam. Of all isolates, 95.3% CnsKP and 94.1% CnsEC were susceptible to aztreonam–avibactam. In C. elegans model, ceftazidime–avibactam and aztreonam–avibactam revealed effective against a blaKPC-producing K. pneumoniae isolate in vivo. Our results propose a positive therapeutic approach for both combinations against carbapenem-nonsusceptible Enterobacteriaceae in Taiwan.

scholarly journals HighIn VitroSusceptibility to the Novel Spiropyrimidinetrione ETX0914 (AZD0914) among 873 Contemporary Clinical Neisseria gonorrhoeae Isolates from 21 European Countries from 2012 to 2014

2015 ◽  
Vol 59 (9) ◽  
pp. 5220-5225 ◽  
Author(s):  
Magnus Unemo ◽  
Johan Ringlander ◽  
Catherine Wiggins ◽  
Hans Fredlund ◽  
Susanne Jacobsson ◽  
...  
Keyword(s):  
Neisseria Gonorrhoeae ◽  
European Countries ◽  
Cross Resistance ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
The Novel ◽  
Content Type ◽  
Agar Dilution

ABSTRACTResistance inNeisseria gonorrhoeaeagainst all antimicrobials available for the treatment of gonorrhea has emerged. The first gonococcal strains with high-level resistance to ceftriaxone, the last option for first-line empirical antimicrobial monotherapy, were recently described. Consequently, new treatment options are essential. In this study, thein vitroactivity of the novel spiropyrimidinetrione ETX0914 (AZD0914), a DNA topoisomerase II inhibitor, was investigated among contemporary consecutive clinicalN. gonorrhoeaeisolates obtained in 21 European countries and compared to the activities of antimicrobials currently or previously recommended for treatment. Consecutive clinicalN. gonorrhoeaeisolates (n= 873) cultured in 21 European countries from 2012 to 2014 were examined for their susceptibility to ETX0914. The MICs of ETX0914 were determined using the agar dilution method. For comparison, the MICs of ceftriaxone, cefixime, azithromycin, and ciprofloxacin were determined using Etest or the agar dilution method. For ETX0914, the MIC range, modal MIC, MIC50, and MIC90were ≤0.002 to 0.25 mg/liter, 0.125 mg/liter, 0.064 mg/liter, and 0.125 mg/liter, respectively. The MIC values were substantially lower than those of the fluoroquinolone ciprofloxacin and most other antimicrobials examined. No cross-resistance with any other examined antimicrobial was observed. In conclusion, thein vitrosusceptibility to the novel spiropyrimidinetrione ETX0914 (AZD0914) among 873 contemporary clinical isolates from 21 European countries was high, and no cross-resistance to antimicrobials currently or previously used for gonorrhea treatment was indicated. Additional studies investigating thein vitroandin vivoinduction and mechanisms of ETX0914 resistance in gonococci, pharmacokinetics/pharmacodynamics in modeling/simulations and in humans, and performance in randomized controlled gonorrhea treatment trials are essential.

scholarly journals Helicobacter pylori antibiotic resistance in Brazil: clarithromycin is still a good option

2011 ◽  
Vol 48 (4) ◽  
pp. 261-264 ◽  
Author(s):  
Jaime Natan Eisig ◽  
Fernando Marcuz Silva ◽  
Ricardo Correa Barbuti ◽  
Tomás Navarro-Rodriguez ◽  
Joaquim Prado P Moraes-Filho ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Antibiotic Susceptibility ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Upper Gastrointestinal Endoscopy ◽  
Test Results ◽  
Primary Resistance ◽  
Agar Dilution ◽  
H Pylori

CONTEXT: The antibiotic susceptibility is the cornerstone for the eradication therapies of Helicobacter pylori. OBJECTIVES: To evaluate the prevalence of primary resistance of H. pylori was evaluated in an urban Brazilian population. METHODS:H. pylori isolates were obtained from patients submitted to an upper gastrointestinal endoscopy for the evaluation of dyspeptic symptoms. Biopsies from antrum, corpus and fundus were taken to determine the antibiotic susceptibility of H. pylori isolates. The minimal inhibitory concentration of furazolidone and bismuth were routinely determined by agar dilution method and the minimal inhibitory for amoxicillin, clarithromycin, tetracycline, levofloxacin, and metronidazole were routinely determined with the E-test. RESULTS: Fifty-four patients were included. In vitro antimicrobial susceptibility of H. pylori strains were obtained from 39 patients. Resistance to metronidazole was detected in 20 patients (51%), to clarithromycin in 3 patients (8%), to levofloxacin in 9 patients (23%) and to bismuth in 2 patients (5%). There was no observed resistance to amoxicillin, tetracycline or furazolidone. CONCLUSION: Due to the low amoxicillin and clarithromycin resistance observed in this study, therapies using these antimicrobials remain appropriated first-line H. pylori therapy.

scholarly journals Antifungal and Antibacterial Metabolites from a French Poplar Type Propolis

2015 ◽  
Vol 2015 ◽  
pp. 1-10 ◽  
Author(s):  
Séverine Boisard ◽  
Anne-Marie Le Ray ◽  
Anne Landreau ◽  
Marie Kempf ◽  
Viviane Cassisa ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Antifungal Activity ◽  
Antimicrobial Effect ◽  
Antibacterial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
Weak Activity ◽  
Agar Dilution

During this study, thein vitroantifungal and antibacterial activities of different extracts (aqueous and organic) obtained from a French propolis batch were evaluated. Antifungal activity was evaluated by broth microdilution on three pathogenic strains:Candida albicans, C. glabrata, andAspergillus fumigatus. Antibacterial activity was assayed using agar dilution method on 36 Gram-negative and Gram-positive strains includingStaphylococcus aureus. Organic extracts showed a significant antifungal activity againstC. albicansandC. glabrata(MIC80between 16 and 31 µg/mL) but only a weak activity towardsA. fumigatus(MIC80= 250 µg/mL). DCM based extracts exhibited a selective Gram-positive antibacterial activity, especially againstS. aureus(SA) and several of its methicillin-resistant (MRSA) and methicillin-susceptible (MSSA) strains (MIC10030–97 µg/mL). A new and active derivative of catechin was also identified whereas a synergistic antimicrobial effect was noticed during this study.

scholarly journals In Vitro Antifungal Activity of Polysulfides-Rich Essential Oil of Ferula Latisecta Fruits against Human Pathogenic Dermatophytes

2008 ◽  
Vol 3 (9) ◽  
pp. 1934578X0800300 ◽  
Author(s):  
Mehrdad Iranshahi ◽  
Abdolmajid Fata ◽  
Bahareh Emami ◽  
Bibi Mohadeseh Jalalzadeh Shahri ◽  
Bibi Sedigheh Fazly Bazzaz
Keyword(s):  
Antifungal Activity ◽  
Essential Oil ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Sulfur Containing ◽  
Type Strains ◽  
In Vitro Antifungal Activity

The increase in dermatophytoses and the fact that some patients do not respond well to therapy make it necessary to find new antifungal agents. As part of our ongoing studies on medicinal plants from Iran, we studied antidermatophytic activities of Ferula latisecta essential oil, which had shown considerable antifungal activity in preliminary antimicrobial screening. Antifungal activity was evaluated by determination of MIC values using the agar dilution method on type strains of Candida albicans and dermatophytes. The composition of the oil was characterized by GC and GC/MS analyses. The essential oil was rich in polysulfides (75.2%) and exhibited good activity against Trichophyton rubrum and T. verrucosom for about three weeks, with a MIC value 96 μg/mL. The oil showed antifungal activity, especially against dermatophytes, and the activity is probably related to the sulfur-containing components of the oil. This study has identified that the polysulfides-rich essential oil of Ferula latisecta fruits has activity against a range of human pathogenic dermatophytes, justifying future clinical trials to validate its use as a therapeutic alternative for dermatophytosis.

scholarly journals In Vitro Activities of Garenoxacin (BMS-284756) against 170 Clinical Isolates of Nine Pasteurella Species

2002 ◽  
Vol 46 (9) ◽  
pp. 3068-3070 ◽  
Author(s):  
Ellie J. C. Goldstein ◽  
Diane M. Citron ◽  
C. Vreni Merriam ◽  
Yumi A. Warren ◽  
Kerin L. Tyrrell ◽  
...  
Keyword(s):  
Pasteurella Multocida ◽  
Active Agent ◽  
Culture Collection ◽  
Clinical Isolates ◽  
American Type Culture Collection ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution

ABSTRACT The in vitro susceptibilities of 170 clinical isolates plus 12 American Type Culture Collection strains of Pasteurella species comprising nine species and three Pasteurella multocida subspecies were studied by an agar dilution method. Garenoxacin (BMS-284756), a new des-fluoro(6) quinolone, was active at ≤0.06 μg/ml against all isolates, including four β-lactamase-producing strains, with >90% of the strains susceptible to ≤0.008 μg/ml. Garenoxacin was generally 1 to 2 dilutions more active than levofloxacin and moxifloxacin and was the most active agent tested. Cefoxitin required 1 μg/ml for inhibition of 51 of 182 (29%) of strains, and 3 strains (also β-lactamase producers) were resistant to doxycycline.

In vitro synergy testing of macrolide-quinolone combinations against 41 clinical isolates of Legionella.

1996 ◽  
Vol 40 (6) ◽  
pp. 1419-1421 ◽  
Author(s):  
S J Martin ◽  
S L Pendland ◽  
C Chen ◽  
P Schreckenberger ◽  
L H Danziger
Keyword(s):  
Yeast Extract ◽  
Antimicrobial Therapy ◽  
Clinical Isolates ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Agar Dilution ◽  
Legionella Species ◽  
Checkerboard Assay ◽  
Synergy Testing

Combination antimicrobial therapy against Legionella species has not been well studied. Several quinolones have activity against Legionella strains, which prompted this in vitro search for a synergistic combination with the macrolides. By a checkerboard assay, erythromycin, clarithromycin, and azithromycin, each in combination with ciprofloxacin and levofloxacin, were tested for synergy against 46 isolates of Legionella. The agar dilution method was employed using buffered charcoal-yeast extract media. A final inoculum of 10(4) CFU per spot was prepared from 24-h growth of each isolate. Plates were incubated at 35 degrees C for 48 h. Synergy, partial synergy, additive effect, or indifference was observed for all combinations of antibiotics tested. There was no antagonism observed. Synergy occurred to a significantly greater extent for the clarithromycin-levofloxacin (P = 0.0001) and azithromycin-levofloxacin (P = 0.003) combinations versus erythromycin-levofloxacin. The azithromycin-ciprofloxacin combination demonstrated significantly greater synergy than did either erythromycin-ciprofloxacin (P = 0.003) or clarithromycin-ciprofloxacin (P = 0.001). The newer macrolides clarithromycin and azithromycin may be more active in combination with a fluoroquinolone than is erythromycin.

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