scholarly journals Comparison of the Susceptibilities of Burkholderia pseudomallei to Meropenem and Ceftazidime by Conventional and Intracellular Methods

2004 ◽  
Vol 48 (8) ◽  
pp. 2999-3005 ◽  
Author(s):  
T. J. J. Inglis ◽  
F. Rodrigues ◽  
P. Rigby ◽  
R. Norton ◽  
B. J. Currie
Keyword(s):  
Clinical Outcomes ◽  
Burkholderia Pseudomallei ◽  
Antimicrobial Agents ◽  
Bacterial Species ◽  
Bacterial Count ◽  
In Vitro Test ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method

ABSTRACT The effect of the two antibiotics ceftazidime and meropenem on a collection of 46 Burkholderia pseudomallei isolates representing clinical and environmental sources across northern Australia was investigated by using a series of in vitro test methods. The susceptibility testing methods used included Kirby-Bauer disk diffusion, Etest MIC, broth microdilution MIC, and a modification of the microdilution method in which Acanthamoeba cells were added to simulate the effect of a professional phagocytic cell on test outcome. In a semiquantitative validation coculture series, the majority of bacteria were intracellular up to a multiplicity of infection of 10 bacteria to one ameba. The optical density and bacterial count (log10 CFU/ml) correlated across the range tested (r 2 = 0.77; P < 0.0001). Susceptibility test results were compared against clinical outcomes. The MICs of ceftazidime were consistently higher than those of meropenem by all three methods. The MICs of both agents were significantly higher when Acanthamoeba trophozoites were added to the broth microdilution method. Conventional and intracellular MIC results were consistent for clinical isolates from the Western Australian outbreak cluster despite the wide variety of clinical outcomes. Further development of the intracellular MIC method is expected to help assess the efficacy of antimicrobial agents on this bacterial species in an intracellular setting.

scholarly journals Susceptibility of bacteria of the Enterococcus genus isolated on Lithuanian poultry farms

2010 ◽  
Vol 54 (No. 12) ◽  
pp. 583-588 ◽  
Author(s):  
M. Ruzauskas ◽  
R. Siugzdiniene ◽  
V. Spakauskas ◽  
J. Povilonis ◽  
V. Seputiene ◽  
...  
Keyword(s):  
Antimicrobial Agents ◽  
Broth Microdilution ◽  
Diagnostic Systems ◽  
Microtitre Plate ◽  
Predominant Species ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Poultry Farms ◽  
Clinical Breakpoints

The aim of this study was to test and analyse the antimicrobial susceptibility of <I>Enterococcus</I> isolates from Lithuanian poultry farms. Investigations were carried out during the years 2008–2009. The sampling sites, located all over the country, included eight poultry farms of large capacity. All samples were collected from broilers. <I>Enterococcus</I> spp. were isolated from intestines immediately after slaughtering. A total of 160 samples were collected, 20 samples from each farm. The MICs (Minimum Inhibitory Concentrations) of eleven antimicrobial agents were determined for each of the isolates using the broth microdilution method with specific microtitre plate panels (Trek Diagnostic Systems, Inc.). Susceptibility according to clinical breakpoints of chloramphenicol, linezolid, erythromycin, penicillin, quinupristin/dalfopristin, tetracycline, vancomycin, ciprofloxacin and nitrofurantoin was evaluated. One hundred and forty seven samples (92%) from a total of 160 tested samples were positive for <I>Enterococcus</I> spp., however, only 74 strains were selected as non-duplicate isolates. The most predominant species were identified as <I>E. faecium</I> (38%), <I>E. faecalis</I> (17.5%), <I>E. gallinarum</I> (12%) and <I>E. casseliflavus</I> (12%). The most frequent resistance properties were resistances to tetracycline (75.6%), erythromycin (56.8%) and ciprofloxacin (41.9%). No strains resistant to vancomycin and linezolid were found. High percentages of susceptibility to chloramphenicol (82.4%) and penicillin (71.6%) were also observed. A high MIC of tigecycline (≥ 1 mg/l) to 12.2% of enterococci was determined during this study. 44.6% of tested strains had a high MIC (≥ 64 mg/l) to tylosin. There was no significant correlation found between resistances of different species to different antimicrobial agents <I>in vitro</I>.

In vitro activities of acetylmidecamycin and other antimicrobials against human macrolide-resistant Mycoplasma pneumoniae isolates

2020 ◽  
Vol 75 (6) ◽  
pp. 1513-1517 ◽  
Author(s):  
Na Wang ◽  
Yunheng Zhou ◽  
Hong Zhang ◽  
Yang Liu
Keyword(s):  
Mycoplasma Pneumoniae ◽  
Antimicrobial Agents ◽  
Mycoplasma Hominis ◽  
Clinical Isolates ◽  
Mycoplasma Species ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Ureaplasma Spp

Abstract Objectives To assess the in vitro activities of acetylmidecamycin, a 16-membered macrolide, and 11 other antimicrobial agents against human mycoplasmas. Methods A total of 187 clinical isolates, Mycoplasma pneumoniae (n = 110), Mycoplasma hominis (n = 26) and Ureaplasma species (n = 51), were included in this study. The MICs of 12 antimicrobial agents, including acetylmidecamycin, thiamphenicol, chloramphenicol and some other macrolides, fluoroquinolones and tetracyclines, for these clinical isolates were determined by the broth microdilution method. Results For M. pneumoniae, the MIC90 values of the tested macrolides were: acetylmidecamycin (1 mg/L)&lt;josamycin (4 mg/L)&lt;midecamycin (8 mg/L)&lt;azithromycin (16 mg/L)&lt;erythromycin (&gt;128 mg/L). Thiamphenicol and chloramphenicol had the same MIC90 (2 mg/L). For Ureaplasma species, the MIC90 values were: acetylmidecamycin (0.25 mg/L)&lt;josamycin (0.5 mg/L)=midecamycin&lt;azithromycin (1 mg/L)=erythromycin. Chloramphenicol had a lower MIC90 (2 mg/L) than that of thiamphenicol (4 mg/L). For M. hominis, the MIC90 values were: acetylmidecamycin (0.25 mg/L)&lt;josamycin (0.5 mg/L)&lt;midecamycin (2 mg/L)&lt;azithromycin (&gt;128 mg/L)=erythromycin. The MIC90 values of chloramphenicol and thiamphenicol were 2 and 4 mg/L, respectively. Conclusions The results indicated that acetylmidecamycin and thiamphenicol are active in vitro against the most common mycoplasma species infecting humans, including those resistant to macrolides and fluoroquinolones. Acetylmidecamycin and thiamphenicol might be a promising option for clinicians to treat infections caused by Mycoplasma and Ureaplasma spp., particularly macrolide-resistant M. pneumoniae in paediatrics and fluoroquinolone-resistant M. hominis in adults. Further investigation of their clinical roles in treating infections caused by these organisms is warranted.

scholarly journals Cannabidiol (CBD) repurposing as antibacterial: promising therapy of CBD plus polymyxin B against superbugs

2021 ◽  
Author(s):  
Nathalia Abichabki ◽  
Luisa Vieira Zacharias ◽  
Natalia Columbaro Moreira ◽  
Fernando Bellissimo-Rodrigues ◽  
Fernanda de Lima Moreira ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Species ◽  
Public Health Problem ◽  
Polymyxin B ◽  
Multidrug Resistant ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Rescue Treatment ◽  
Broth Microdilution Method

Multidrug-resistant (MDR) and extensively drug-resistant (XDR) bacteria are a major worldwide public health problem. In the last decades, resistance to last-resort antibiotics such as polymyxin B (PB) have been increasingly observed among these superbugs, compromising the effectiveness of antimicrobial therapy. The present study aimed (i) to assess the ultrapure Cannabidiol (CBD) antibacterial activity against a broad diversity of Gram-negative (GN) and Gram-positive (GP) bacteria (44 different species, 95 strains), comprising standard strains and clinical isolates, and (ii) to investigate the antibacterial activity of the combination CBD + PB against GN bacteria, including chromosomal- and plasmid-acquired PB-resistant and intrinsically PB-resistant GNB. We evaluated CBD in vitro antibacterial activity using the standard broth microdilution method, and the antibacterial activity of the combination CBD + PB was screened using the standard broth microdilution and confirmed by checkerboard assay. CBD exhibited antibacterial activity against different GP bacterial species, lipooligosaccharide (LOS)-expressing GN diplococcus (GND) (Neisseria gonorrhoeae, Neisseria meningitidis, and Moraxella catarrhalis), and Mycobacterium tuberculosis. The combination CBD + PB exhibited antibacterial activity against PB-resistant GNB (e.g., Klebsiella pneumoniae) as well as additive and/or synergistic effect against LOS-expressing GND. The antibacterial activity of the combination CBD + PB against Pseudomonas aeruginosa and plasmid-mediated colistin-resistant (MCR-1) E. coli strains could be only demonstrated in the presence of phenylalanine-arginine-beta-naphthylamide (PA-beta-N). In conclusion, our results show promising translational potential of the combination CBD + PB against MDR and XDR GNB, including PB-resistant K. pneumoniae, highlighting its potential as a rescue treatment for life-threatening infections caused by these superbugs.

scholarly journals In Vitro Activities of the Novel Oxazolidinones DA-7867 and DA-7157 against Rapidly and Slowly Growing Mycobacteria

2006 ◽  
Vol 50 (12) ◽  
pp. 4027-4029 ◽  
Author(s):  
Lucio Vera-Cabrera ◽  
Barbara A. Brown-Elliott ◽  
Richard J. Wallace ◽  
Jorge Ocampo-Candiani ◽  
Oliverio Welsh ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Clinical Isolates ◽  
Nontuberculous Mycobacterium ◽  
The Novel ◽  
Broth Microdilution ◽  
Reference Species ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Aerobic Actinomycetes

ABSTRACT DA-7867 and DA-7157 are oxazolidinones active against pathogenic aerobic actinomycetes including Nocardia spp. and Mycobacterium tuberculosis. However, the activity of these drugs against nontuberculous mycobacterium (NTM) species is not known. In this work, we compared the susceptibilities of 122 clinical isolates and 29 reference species of both rapidly growing and slowly growing mycobacteria to linezolid, DA-7867, and DA-7157 by the broth microdilution method. The MICs for 50 and 90% of the strains tested (MIC50s and MIC90s, respectively) of DA-7867 and DA-7157 were lower than those of linezolid. In all of the cases, a MIC90 of <8 μg/ml was observed for all of the species tested in both groups of NTM. For M. kansasii and M. marinum isolates, the MIC90s of both DA-7867 and DA-7157 were less than 0.5 μg/ml. These results demonstrate the potential of these compounds to treat NTM infections.

scholarly journals In Vitro Activities of the New Antifungal Triazole SCH 56592 against Common and Emerging Yeast Pathogens

2000 ◽  
Vol 44 (1) ◽  
pp. 226-229 ◽  
Author(s):  
Francesco Barchiesi ◽  
Daniela Arzeni ◽  
Annette W. Fothergill ◽  
Luigi Falconi Di Francesco ◽  
Francesca Caselli ◽  
...  
Keyword(s):  
Clinical Laboratory ◽  
Clinical Development ◽  
National Committee ◽  
In Vitro Activity ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Vitro Data ◽  
In Vitro Data

ABSTRACT A broth microdilution method performed in accordance with the National Committee for Clinical Laboratory Standards guidelines was used to compare the in vitro activity of the new antifungal triazole SCH 56592 (SCH) to that of fluconazole (FLC), itraconazole (ITC), and ketoconazole (KETO) against 257 clinical yeast isolates. They included 220 isolates belonging to 12 different species of Candida, 15 isolates each of Cryptococcus neoformans andSaccharomyces cerevisiae, and seven isolates ofRhodotorula rubra. The MICs of SCH at which 50% (MIC50) and 90% (MIC90) of the isolates were inhibited were 0.06 and 2.0 μg/ml, respectively. In general, SCH was considerably more active than FLC (MIC50 and MIC90 of 1.0 and 64 μg/ml, respectively) and slightly more active than either ITC (MIC50 and MIC90 of 0.25 and 2.0 μg/ml, respectively) and KETO (MIC50 and MIC90 of 0.125 and 4.0 μg/ml, respectively). Our in vitro data suggest that SCH has significant potential for clinical development.

scholarly journals Evaluation of a Modified EUCAST Fragmented-Mycelium Inoculum Method forIn VitroSusceptibility Testing of Dermatophytes and the Activity of Novel Antifungal Agents

2015 ◽  
Vol 59 (6) ◽  
pp. 3675-3682 ◽  
Author(s):  
B. Risslegger ◽  
C. Lass-Flörl ◽  
G. Blum ◽  
M. Lackner
Keyword(s):  
Antifungal Agents ◽  
Susceptibility Testing ◽  
Preparation Method ◽  
Antifungal Susceptibility ◽  
Broth Microdilution ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Inoculum Preparation ◽  
Minimal Effective Concentration

ABSTRACTFor antifungal susceptibility testing of nonsporulating or poorly sporulating dermatophytes, a fragmented-mycelium inoculum preparation method was established and compared to broth microdilution testing according to CLSI and EUCAST guidelines. Moreover, thein vitroactivity of new antifungal agents against dermatophytes was evaluated. Agreement between the mycelial inoculum method and the CLSI broth microdilution method was high (93% to 100%). Echinocandins (minimal effective concentration [MEC], ≤0.5 mg/liter) and posaconazole (MIC, ≤3.00 mg/liter) showed good activity against all tested dermatophytes.

Synthesis and Antibacterial Activities of Amidine Substituted Monocyclic β-Lactams

2021 ◽  
Vol 17 ◽  
Author(s):  
Lijuan Zhai ◽  
Lili He ◽  
Yuanbai Liu ◽  
Ko Ko Myo ◽  
Zafar Iqbal ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Bacterial Species ◽  
Antimicrobial Effect ◽  
Antibacterial Activities ◽  
Lead Target ◽  
Bacterial Strains ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Clinical Interest

Background: Mononcyclic β-lactams are regarded as the most resistant class of β-lactams against a series of β-lactamases though possess limited antibacterial activity. Aztreonam being the first clinically approved monobactam needs broad-spectrum efficacy through structural modification. Objective: We strive to synthesize a number of monocyclic β-lactams by varying the substituents at N1, C3 and C4 positions of azetidinone ring and study the antimicrobial effect on variable bacterial strains. Methods: Seven new monobactam derivatives 23a-g, containing substituted-amidine moieties linked to the azetidinone ring via thiazole linker, were synthesized through multistep synthesis. The final compounds were investigated for their in vitro antibacterial activities using broth microdilution method, against ten bacterial strains of clinical interest. The minimum inhibitory concentrations (MICs) of newly synthesized derivatives were compared with aztreonam, ceftazidime and meropenem, existing clinical antibiotics. Results: All compounds 23a-g showed higher antibacterial activities (MIC 0.25 µg/mL to 64 µg/mL) against tested strains as compared to aztreonam (MIC 16 µg/mL to >64 µg/mL) and ceftazidime (MIC >64 µg/mL). However all compounds, except 23d, exhibited lower antibacterial activity against all tested bacterial strains as compared to meropenem. Conclusion: Compound 23d showed comparable or improved antibacterial activity (MIC 0.25 µg/mL to 2 µg/mL) to meropenem (MIC 1 µg/mL to 2 µg/mL) in case of seven bacterial species. Therefore, compound 23d may be valuable lead target for further investigations against multi-drug resistant Gram-negative bacteria.

In vitro activity of antimicrobial agents with and without sulbactam, EDTA and sulbactam-EDTA on ESBLs-producing Escherichia coli isolated from healthy Tibetan yaks

2020 ◽  
Author(s):  
Baoguang Liu ◽  
Xiaoling Yuan ◽  
Yiheng Chen ◽  
Xiaoshen Li ◽  
Ming Bai ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Nasal Swab ◽  
Antimicrobial Agents ◽  
Synergistic Effects ◽  
E Coli ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Third Generation Cephalosporins ◽  
Enhance Activity

Abstract Background The spread of ESBLs-producing bacteria has been strikingly rapid in many regions of the world and it causes therapeutic difficulties in everyday practice. The aims of this study were to investigate the prevalence and susceptibilities of ESBLs-producing Escherichia coli isolates from healthy Tibetan yaks in China, to evaluate the activity of drug combinations on ESBLs-producing E. coli isolates. Methods From July 2018 to August 2019, a total of 750 nasal swab samples were tested for the presence of E. coli and ESBLs-producing strains. The MICs of 11 antimicrobial agents alone and combinations with sulbactam, EDTA or sulbactam-EDTA against 240 ESBLs-producing E.coli strains were determined by the broth microdilution method. Results Overall, 59.87% (n = 449) of the samples were positive for E. coli, 240 (53.45%) of 449 E. coli isolates were confirmed to be ESBLs-producing. The addition of sulbactam to the third generation cephalosporins, amikacin and fosfomycin for all isolates resulted in low MICs, increasing the level of susceptibility from 0, 0 and 0% to 50 ~ 87.5, 4.2 and 100% respectively. The addition of EDTA to fluoroquinolones, doxycycline, florfenicol, amikacin and fosfomycin, showed improved activities and resulted in low MICs, increasing the level of susceptibility from 0, 0, 8.3, 0 and 0% to 4.2 ~ 29.2, 33.3, 33.3, 66.7 and 45.8%, respectively. All other antibacterials (except fluoroquinolones, doxycycline and florfenicol), when combined with sulbactam-EDTA, were found to be more active than combinations only with sulbactam or with EDTA against most of isolates, with lower MIC50s and MIC90s. Conclusion In conclusion, ESBLs-producing E. coli isolates were widespread in healthy Tibetan yaks in China. ESBLs-producing E. coli isolates exhibited varying degrees of multidrug resistance. This study these findings suggested that sulbactam can enhance activity of β-lactams and some non-β-lactams of antimicrobial agents and had a synergistic effects with EDTA in improving activities of some families of antimicrobials.

scholarly journals Susceptibility trends of ceftolozane/tazobactam and comparators when tested against European Gram-negative bacterial surveillance isolates collected during 2012–18

2020 ◽  
Vol 75 (10) ◽  
pp. 2907-2913 ◽  
Author(s):  
Helio S Sader ◽  
Cecilia G Carvalhaes ◽  
Leonard R Duncan ◽  
Robert K Flamm ◽  
Dee Shortridge
Keyword(s):  
Eastern Europe ◽  
Active Compound ◽  
Western Europe ◽  
Antimicrobial Agents ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Microdilution Method ◽  
Broth Microdilution Method ◽  
Systemic Infections

Abstract Background The Program to Assess Ceftolozane/Tazobactam Susceptibility (PACTS) monitors the in vitro activity of ceftolozane/tazobactam and numerous antimicrobial agents against Gram-negative bacteria worldwide. Objectives To evaluate the activity of ceftolozane/tazobactam and resistance trends among Pseudomonas aeruginosa and Enterobacterales isolates in Europe between 2012 and 2018. Methods P. aeruginosa (7503) and Enterobacterales (30 582) isolates were collected from 53 medical centres in 26 countries in Europe and the Mediterranean region and tested for susceptibility by reference broth microdilution method in a central laboratory. MIC results were interpreted using EUCAST criteria. Results Ceftolozane/tazobactam was the most active compound tested against P. aeruginosa isolates after colistin, with overall susceptibility rates of 94.1% in Western Europe and 80.9% in Eastern Europe. Moreover, ceftolozane/tazobactam retained activity against 75.2% and 59.2% of meropenem-non-susceptible P. aeruginosa isolates in Western and Eastern Europe, respectively. Tobramycin was the third most active compound tested against P. aeruginosa, with susceptibility rates of 88.6% and 70.9% in Western and Eastern Europe, respectively. Ceftolozane/tazobactam was active against 94.5% of all Enterobacterales and 96.1% of meropenem-susceptible isolates from Western Europe. In Eastern Europe, ceftolozane/tazobactam was active against 79.4% of Enterobacterales overall and 86.2% of meropenem-susceptible isolates. Discussion Antimicrobial susceptibility rates for agents commonly used to treat serious systemic infections varied widely among nations and geographic regions and were generally lower in Eastern Europe compared with Western Europe. Ceftolozane/tazobactam demonstrated potent activity against P. aeruginosa, including MDR strains, and retained activity against most meropenem-susceptible Enterobacterales causing infection in European medical centres.

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