scholarly journals Evaluation of ceftazidime/avibactam alone and in combination with amikacin, colistin and tigecycline against Klebsiella pneumoniae carbapenemase-producing K. pneumoniae by in vitro time-kill experiment

PLoS ONE ◽  
2021 ◽  
Vol 16 (10) ◽  
pp. e0258426
Author(s):  
Fangzhou Wang ◽  
Qian Zhou ◽  
Xiuwen Yang ◽  
Yan Bai ◽  
Junchang Cui
Keyword(s):  
Klebsiella Pneumoniae ◽  
Antibacterial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Klebsiella Pneumoniae Carbapenemase ◽  
Single Drug ◽  
Mueller Hinton ◽  
Mutant Prevention Concentration ◽  
Time Kill

Klebsiella pneumoniae carbapenemase-producing K. pneumoniae (KPC-Kp) poses a major threat to human health worldwide. Combination therapies of antibiotics with different mechanisms have been recommended in literatures. This study assessed in vitro antibacterial activities and synergistic activities of ceftazidime/avibactam alone and in combinations against KPC-Kp. In total, 70 isolates from 2 hospitals in Beijing were examined in our study. By using the agar dilution method and broth dilution method, we determined the minimum inhibitory concentration (MIC) of candidate antibiotics. Ceftazidime/avibactam demonstrated promising susceptibility against KPC-Kp (97.14%). Synergistic activities testing was achieved by checkerboard method and found ceftazidime/avibactam-amikacin displayed synergism in 90% isolates. Ceftazidime/avibactam-colistin displayed partial synergistic in 43% isolates, and ceftazidime/avibactam-tigecycline displayed indifference in 67% isolates. In time-kill assays, antibiotics at 1-fold MIC were mixed with bacteria at 1 × 105 CFU/ml and Mueller-Hinton broth (MHB). Combinations of ceftazidime/avibactam with amikacin and tigecycline displayed better antibacterial effects than single drug. Ceftazidime/avibactam-colistin combination did not exhibit better effect than single drug. In KPC-Kp infections, susceptibility testing suggested that ceftazidime/avibactam may be considered as first-line choice. However, monotherapy is often inadequate in infection management. Thus, our study revealed that combination therapy including ceftazidime/avibactam colistin and ceftazidime/avibactam tigecycline may benefit than monotherapy in KPC-Kp treatment. Further pharmacokinetic/pharmacodynamic and mutant prevention concentration studies should be performed to optimize multidrug-regimens.

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 Time-Kill and Synergism Studies of Ceftobiprole against Enterococcus faecalis, Including β-Lactamase-Producing and Vancomycin-Resistant Isolates

2007 ◽  
Vol 51 (6) ◽  
pp. 2043-2047 ◽  
Author(s):  
Cesar A. Arias ◽  
Kavindra V. Singh ◽  
Diana Panesso ◽  
Barbara E. Murray
Keyword(s):  
Enterococcus Faecalis ◽  
Vitro Activity ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
In Vitro Activity ◽  
Inoculum Concentration ◽  
High Inoculum ◽  
Vancomycin Resistant ◽  
Time Kill

ABSTRACT Ceftobiprole (BAL9141) is an investigational cephalosporin with broad in vitro activity against gram-positive cocci, including enterococci. Ceftobiprole MICs were determined for 93 isolates of Enterococcus faecalis (including 16 β-lactamase [Bla] producers and 17 vancomycin-resistant isolates) by an agar dilution method following the Clinical and Laboratory Standards Institute recommendations. Ceftobiprole MICs were also determined with a high inoculum concentration (107 CFU/ml) for a subset of five Bla producers belonging to different previously characterized clones by a broth dilution method. Time-kill and synergism studies (with either streptomycin or gentamicin) were performed with two β-lactamase-producing isolates (TX0630 and TX5070) and two vancomycin-resistant isolates (TX2484 [VanB] and TX2784 [VanA]). The MICs of ceftobiprole for 50 and 90% of the isolates tested were 0.25 and 1 μg/ml, respectively. All Bla producers and vancomycin-resistant isolates were inhibited by concentrations of ≤1 and ≤4 μg/ml, respectively, at the standard inoculum concentration. Ceftobiprole MICs at a high inoculum concentration for a subset of five Bla+ E. faecalis isolates were ≤1 μg/ml. Bactericidal activity was observed against four isolates tested at concentrations as low as 1 μg/ml regardless of the production of β-lactamase or vancomycin resistance. A combination of ceftobiprole (0.5 μg/ml) and streptomycin (25 μg/ml) was synergistic against Bla+ TX0630 and TX5070. Ceftobiprole (0.5 μg/ml) plus gentamicin (10 μg/ml) was synergistic against VanB isolate TX2484 and showed enhanced killing, but not synergism, against TX2784 (VanA), despite the absence of high-level resistance to gentamicin. In conclusion, ceftobiprole exhibited good in vitro activity against E. faecalis, including Bla+ and vancomycin-resistant strains, and exhibited synergism with aminoglycosides against selected isolates.

scholarly journals Synthesis andIn VitroAntibacterial Activity of New 2-(1-Methyl-4-nitro-1H-imidazol-5-ylsulfonyl)-1,3,4-thiadiazoles

2011 ◽  
Vol 8 (3) ◽  
pp. 1120-1123 ◽  
Author(s):  
Bahram Letafat ◽  
Negar Mohammadhosseini ◽  
Ali Asadipour ◽  
Alireza Foroumadi
Keyword(s):  
Staphylococcus Aureus ◽  
Staphylococcus Epidermidis ◽  
Antibacterial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Gram Positive ◽  
Gram Negative ◽  
Gram Positive Bacteria ◽  
Agar Dilution

In the present study we report the synthesis and antibacterial activity of a new series 2-(1-methyl-4-nitro-1H-imidazol-5-ylsulfonyl)-1,3,4-thiadiazoles (6a-c). Compounds6a-cwere testedin vitroby the conventional agar dilution method against a panel of microorganisms including gram-negative and gram-positive bacteria. Compound6bwith 5-(5-nitrofuran-2-yl)-residue on 1,3,4-thiadiazole scaffold have shown promising antibacterial activities against gram-positive bacteria includingStaphylococcus aureus, Staphylococcus epidermidisandBacillus subtilis.

Computer-aided structural optimization, synthesis, evaluation of the antimicrobial and cytotoxic activity of some pyrazoline derivatives

MedPharmRes ◽  
2021 ◽  
Vol 6 (1) ◽  
pp. 33-39
Author(s):  
Tai Duc Nguyen ◽  
Du Nguyen Hai Ly ◽  
Thi Hong Tuoi Do ◽  
Phuong Thi Ngoc Huynh
Keyword(s):  
Antimicrobial Activity ◽  
Anticancer Activity ◽  
Antibacterial Activities ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Moderate Activity ◽  
Docking Model ◽  
Ic50 Values ◽  
Relationship Of

Introduction: In the last few decades, pyrazoline-based substances have emerged as potential antimicrobial and anticancer candidates. In concern with antimicrobial activity, this study aims to build a docking model to predict the structure of potential 2-pyrazoline derivatives. The cytotoxicity of some compounds was also evaluated to get insight into the structure–anticancer activity relationship of the 2-pyrazoline derivatives. Methods: Docking models were built on virtual FabH enzymes using FlexX platform with 2-pyrazoline derivatives served as test sets. Afterward, derivatives with high docking scores were chemically synthesized and evaluated for antibacterial activity using the agar dilution method. Furthermore, MTT assay was used to assess the cytotoxicity of these compounds. Results: The docking score and the in vitro minimum inhibitory concentration (MIC) value on Staphylococcus aureus (S. aureus) bacteria strongly correlate with an R-square value of 0.6751 (p < 0.0001). Four 2 pyrazoline derivatives were synthesized and evaluated for antimicrobial activity. Their MIC values on S. aureus range between 4 and 16 μg/mL, consistent with ones predicted by the docking model. Apropos cytotoxic properties, a series of 2-pyrazolines exhibit a moderate activity on HepG2, RD, and MDA-MB-231. The most active compound, HP10, has the IC50 values on these cell lines. which are 26.62 μM, 17.74 μM, 14.47 μM, respectively. Conclusion: Our research built a docking model on the virtual S. aureus FabH enzyme with high potential in predicting antibacterial activities of different 2-pyrazoline derivatives. Moreover, our cytotoxicity results provided data for further studies on the anticancer activity of these promising derivatives.

scholarly journals In vitro Assessment of Euclea crispa (Thunb.) Leaf Extracts against Campylobacter spp. and Escherichia coli - Common Diarrhoeal Agents

2018 ◽  
Vol 6 (4) ◽  
Author(s):  
Kazeem Adekunle Alayande ◽  
Carolina (H) Pohl ◽  
Anofi Omotayo Tom Ashafa
Keyword(s):  
Escherichia Coli ◽  
Mortality Rate ◽  
Ethyl Acetate ◽  
Leaf Extract ◽  
Total Mortality ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Leaf Extracts ◽  
Time Kill

Diarrhoea is a common childhood disease with high mortality rate. This study thus aimed at assessing effect of Euclea crispa leaf extract and its fractions against diarrhoea causing bacterial isolates and determining time-kill dynamics by each of the potent fractions. Susceptibility of each isolates was determined by agar well diffusion while the minimum bacteriostatic and bactericidal concentrations were determined by agar dilution method. Time-Kill dynamics was evaluated over a period of 120 min against Escherichia coli (1323) representing Gram negative isolates. The zones of inhibition exhibited by the leaf extract at 20 mg/ml range between 17±0.28 and 22±0.00 mm while that of the partitioned fractions at 10 mg/ml are between 14±0.00 and 22±0.00 mm. MICs of the leaf extract range between 0.31 and 2.50 mg/ml. The lowest MIC (0.08 mg/ml) is exhibited by the fractions partitioned into ethyl acetate, n-butanol and water while that of n-hexane and chloroform is 0.16 mg/ml. The lowest MBC exhibited by all the fractions is 0.31 mg/ml except that of the chloroform (1.25 mg/ml). Total mortality was achieved by the ethyl acetate fraction at a concentration of 2 × MIC after 120 min of contact time, meanwhile the mortality rate achieved by n-butanol, n-hexane, aqueous and chloroform fractions were 98, 94.6, 91.8 and 83.7% respectively under similar condition. This study showcase significant antidiarrhoeal potential of Euclea crispa leaf extracts and equally indicates a source of readily available therapeutic agent against diarrhoeal infection in South Africa and environs.

scholarly journals The Antibacterial Activity of Mass Galla Chinesis et Camelliae Fermentata on Helicobacter pylori Infection

2018 ◽  
Vol 2018 ◽  
pp. 1-6
Author(s):  
Jing Yu ◽  
Hui Ye ◽  
Jiang Li ◽  
Ning Li ◽  
Zong-ming Shi ◽  
...  
Keyword(s):  
Helicobacter Pylori ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Rapid Urease Test ◽  
Dosage Group ◽  
Urease Test ◽  
H Pylori ◽  
Time Kill

Mass Galla chinesis et camelliae Fermentata (Chinese gall leaven, CGL) was investigated for activities against Helicobacter pylori (H. pylori) both in vitro and in vivo. The agar dilution method and time-kill curves, as in vitro assays and an in vivo study using a Kunming mice model, were performed. CGL demonstrated a strong anti-Helicobacter pylori activity in vitro with the minimal inhibitory concentrations (MICs) against multiple H. pylori strains of 0.5~8 mg/ml and the decreasing trend time-kill curves when increasing CGL concentrations. H. pylori eradication rates in vivo were evaluated based on rapid urease test (RUT) and histopathologic criteria. Results revealed that the eradication rates in the CGL groups were 40% (4/10) in the high dosage group, 33% (4/11) in the medium dosage group, and 18% (2/11) in the low dosage group, with the difference between the high dosage and H. pylori control groups being significant (P=0.035). The H. pylori colonization scores could be reduced partly by CGL. These in vivo results demonstrated that CGL in a rationally high dosage might be the most effective.

In vitro activity of recombinant lysostaphin against Staphylococcus aureus isolates from hospitals in Beijing, China

2007 ◽  
Vol 56 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Xin-Yi Yang ◽  
Cong-Ran Li ◽  
Ren-Hui Lou ◽  
Yue-Ming Wang ◽  
Wei-Xin Zhang ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Bactericidal Activity ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
Hospital Patients ◽  
Agar Dilution ◽  
Kill Curve ◽  
Time Kill ◽  
Beijing China

Lysostaphin is a glycylglycine endopeptidase. It cleaves the pentaglycine cross-bridge structure unique to the staphylococcal cell wall and is considered to be a potential drug for Staphylococcus aureus. In the present study, the in vitro activity of recombinant lysostaphin was investigated in 257 S. aureus isolates collected from hospital patients in Beijing, China, by determination of MIC and minimum bactericidal concentration (MBC) and a time–kill curve test. An agar dilution method was used for MIC determination in all of the isolates and a macrobroth dilution method was employed to verify MIC values for a subset of the isolates. All of the S. aureus strains were sensitive to the recombinant lysostaphin with MICs ranging from 0.03 to 2 μg ml−1 in the agar dilution assay. The antibacterial activity of lysostaphin was greater than that of vancomycin and other reference agents. For most of the isolates, the MICs from the agar dilution method were higher than those from the broth dilution method. The MBCs of lysostaphin in the test isolates were between 1- and 8-fold higher than their MIC values. Bactericidal activity (>99.9 % reduction) was observed after 2 h exposure of the isolates to lysostaphin at concentrations of ⩾0.5 MIC. Lysostaphin showed a rapid bactericidal activity against the test strains of meticillin-susceptible S. aureus and meticillin-resistant S. aureus. Its activity at ⩾0.5 MIC was sustained for at least 6 h. These results will be informative for the clinical application and evaluation of lysostaphin.

scholarly journals In Vitro Activities of Daptomycin, Vancomycin, and Penicillin against Clostridium difficile, C. perfringens, Finegoldia magna, and Propionibacterium acnes

2006 ◽  
Vol 50 (8) ◽  
pp. 2728-2731 ◽  
Author(s):  
Kerin L. Tyrrell ◽  
Diane M. Citron ◽  
Yumi A. Warren ◽  
Helen T. Fernandez ◽  
C. Vreni Merriam ◽  
...  
Keyword(s):  
Clostridium Difficile ◽  
Bactericidal Activity ◽  
Propionibacterium Acnes ◽  
Anaerobic Bacteria ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
In Vitro Activity ◽  
Agar Dilution ◽  
Time Kill

ABSTRACT Daptomycin has in vitro activity against gram-positive anaerobic bacteria, although limited numbers of species have been tested. We studied the in vitro activities of daptomycin, vancomycin, and penicillin against more than 100 strains each of Clostridium difficile, C. perfringens, Finegoldia magna, and Propionibacterium acnes. Daptomycin Etest MICs and results from time-kill studies were determined for selected strains. For 392 of 421 strains (93%), daptomycin was inhibitory at ≤1 μg/ml, including 15 of 16 strains of C. difficile with elevated linezolid MICs of 8 and 16 μg/ml, all 32 strains with moxifloxacin MICs of ≥4 μg/ml, and all 16 strains resistant to clindamycin. Daptomycin MICs were also ≤1 μg/ml for all 16 F. magna strains resistant to clindamycin and all 32 strains resistant to tetracycline. Only one strain, a C. perfringens strain, had a MIC of >2 μg/ml to daptomycin. Eighty-five and 92.5% of the Etest MICs were within 1 dilution of the agar dilution method for all drugs at 24 and 48 h, respectively. In time-kill studies, a C. difficile strain was inhibited by both daptomycin and vancomycin at 1, 2, 4, 8, and 24 h; colony counts were decreased by 2.3 to 2.9 log at 24 h. Vancomycin was not bactericidal for C. perfringens; however, daptomycin showed bactericidal activity as early as 1 h at four and eight times the MIC and at 2 and 4 h at two and four times the MIC.

scholarly journals In vitro activity of piperacillin/tazobactam and ertapenem against Bacteroides fragilis and Escherichia coli in pure and mixed cultures

2007 ◽  
Vol 56 (6) ◽  
pp. 798-802 ◽  
Author(s):  
Kênia Valéria dos Santos ◽  
Cláudio Galuppo Diniz ◽  
Simone Cristina Coutinho ◽  
Ana Carolina Morais Apolônio ◽  
Luciana Geralda de Sousa-Gaia ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Bacteroides Fragilis ◽  
Mixed Cultures ◽  
Dilution Method ◽  
Agar Dilution Method ◽  
In Vitro Activity ◽  
E Coli ◽  
Agar Dilution ◽  
Time Kill

Ertapenem and piperacillin/tazobactam are β-lactam antibiotics with a broad spectrum of activity used for the treatment of mixed infections in which Bacteroides fragilis and Escherichia coli play an important aetiological role. In this study, the activities of piperacillin/tazobactam and ertapenem (MIC and time–kill kinetics) against these bacteria were compared. MICs were determined by the agar dilution method, and the time and slope of time–kill curves were analysed. In the in vitro pharmacodynamic assays, pure and mixed cultures of E. coli and B. fragilis were exposed to peak concentrations of ertapenem (8.0 μg ml−1) and piperacillin/tazobactam (64.0/8.0 μg ml−1) for 48 h. Treatment with ertapenem reduced the viability of E. coli and/or B. fragilis by 3 logs in all experiments, whereas piperacillin/tazobactam only affected the viability of B. fragilis. Both drugs exhibited their fastest rates of killing when bacteria were grown in mixed cultures. According to the results, ertapenem exhibited activity similar to that of piperacillin/tazobactam against B. fragilis alone or in mixed culture. However, ertapenem exhibited a markedly higher activity against E. coli alone or in combination with B. fragilis relative to piperacillin/tazobactam.

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