Antimicrobial activity and time kill kinetics of Nigerian Honeys on multi-resistant Enteric Bacilli

This study evaluated the antimicrobial property of the aqueous extract of Citrullus lanatus (watermelon) seeds and its concentration-effect relationship (time-kill studies) on typed bacterial and fungal strains. Crude powdered seeds of Citrullus lanatus were extracted by maceration with water. Antimicrobial assay of the aqueous extracts was determined against Bacillus subtilis (NCTC 8236), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 10145), Staphylococcus aureus (ATCC 25923), and Candida albicans (ATCC 24433) using standard microbiological methods. A total of 106 CFU/mL of each test strain was used as a baseline to carry out the time-kill studies. Extract concentration at minimum inhibitory concentration (MIC), 2MIC and 4MIC were used over a period of 24 hours. Aqueous extract had an intermediate antibacterial activity with inhibition zone diameters (IZD) of 15 - 18 mm and MIC range of 2.5 - 20 mg/mL. Time-kill studies showed a bacteriostatic, non-concentration dependent mode of antimicrobial activity with characteristic regrowth for all test strains. Citrullus lanatus seeds aqueous extract exhibited antimicrobial activity with a bacteriostatic, non-concentration dependent mode of action against test bacterial strains. Further studies aimed at isolating and purifying the antimicrobial principle in the aqueous extract of C. lanatus seed is warranted as this could serve as a potential new antibiotic for treating microbial infections.

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Antimicrobial Activities and Time-Kill Kinetics of Extracts of Selected Ghanaian Mushrooms

Evidence-based Complementary and Alternative Medicine ◽

10.1155/2017/4534350 ◽

2017 ◽

Vol 2017 ◽

pp. 1-15 ◽

Cited By ~ 19

Author(s):

Theresa Appiah ◽

Yaw Duah Boakye ◽

Christian Agyare

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Agents ◽

Schizophyllum Commune ◽

Antimicrobial Properties ◽

Antimicrobial Activities ◽

Methanol Extracts ◽

Test Organisms ◽

Antibacterial And Antifungal ◽

Time Kill ◽

Kinetics Of

The rapid rise of antimicrobial resistance is a worldwide problem. This has necessitated the need to search for new antimicrobial agents. Mushrooms are rich sources of potential antimicrobial agents. This study investigated the antimicrobial properties of methanol extracts of Trametes gibbosa, Trametes elegans, Schizophyllum commune, and Volvariella volvacea. Agar well diffusion, broth microdilution, and time-kill kinetic assays were used to determine the antimicrobial activity of the extracts against selected test organisms. Preliminary mycochemical screening revealed the presence of tannins, flavonoids, triterpenoids, anthraquinones, and alkaloids in the extracts. Methanol extracts of T. gibbosa, T. elegans, S. commune, and V. volvacea showed mean zone of growth inhibition of 10.00±0.0 to 21.50±0.84, 10.00±0.0 to 22.00±1.10, 9.00±0.63 to 21.83±1.17, and 12.00±0.0 to 21.17±1.00 mm, respectively. The minimum inhibitory concentration of methanol extracts of T. gibbosa, T. elegans, S. commune, and V. volvacea ranged from 4.0 to 20, 6.0 to 30.0, 8.0 to 10.0, and 6.0 to 20.0 mg/mL, respectively. Time-kill kinetics studies showed that the extracts possess bacteriostatic action. Methanol extracts of T. gibbosa, T. elegans, S. commune, and V. volvacea exhibited antimicrobial activity and may contain bioactive compounds which may serve as potential antibacterial and antifungal agents.

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Bactericidal Activity, Absence of Serum Effect, and Time-Kill Kinetics of Ceftazidime-Avibactam against β-Lactamase-Producing Enterobacteriaceae and Pseudomonas aeruginosa

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.02894-14 ◽

2014 ◽

Vol 58 (9) ◽

pp. 5297-5305 ◽

Cited By ~ 55

Author(s):

Tiffany R. Keepers ◽

Marcela Gomez ◽

Chris Celeri ◽

Wright W. Nichols ◽

Kevin M. Krause

Keyword(s):

Pseudomonas Aeruginosa ◽

Human Serum ◽

Bactericidal Activity ◽

Minimum Bactericidal Concentration ◽

Wild Type ◽

Content Type ◽

Positive Isolate ◽

New Treatment ◽

Time Kill ◽

Kinetics Of

ABSTRACTAvibactam, a non-β-lactam β-lactamase inhibitor with activity against extended-spectrum β-lactamases (ESBLs), KPC, AmpC, and some OXA enzymes, extends the antibacterial activity of ceftazidime against most ceftazidime-resistant organisms producing these enzymes. In this study, the bactericidal activity of ceftazidime-avibactam against 18Pseudomonas aeruginosaisolates and 15Enterobacteriaceaeisolates, including wild-type isolates and ESBL, KPC, and/or AmpC producers, was evaluated. Ceftazidime-avibactam MICs (0.016 to 32 μg/ml) were lower than those for ceftazidime alone (0.06 to ≥256 μg/ml) against all isolates except for 2P. aeruginosaisolates (1blaVIM-positive isolate and 1blaOXA-23-positive isolate). The minimum bactericidal concentration/MIC ratios of ceftazidime-avibactam were ≤4 for all isolates, indicating bactericidal activity. Human serum and human serum albumin had a minimal effect on ceftazidime-avibactam MICs. Ceftazidime-avibactam time-kill kinetics were evaluated at low MIC multiples and showed time-dependent reductions in the number of CFU/ml from 0 to 6 h for all strains tested. A ≥3-log10decrease in the number of CFU/ml was observed at 6 h for allEnterobacteriaceae, and a 2-log10reduction in the number of CFU/ml was observed at 6 h for 3 of the 6P. aeruginosaisolates. Regrowth was noted at 24 h for some of the isolates tested in time-kill assays. These data demonstrate the potent bactericidal activity of ceftazidime-avibactam and support the continued clinical development of ceftazidime-avibactam as a new treatment option for infections caused byEnterobacteriaceaeandP. aeruginosa, including isolates resistant to ceftazidime by mechanisms dependent on avibactam-sensitive β-lactamases.

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Essential oils as potential anti-staphylococcal agents

Acta veterinaria ◽

10.2478/acve-2018-0008 ◽

2018 ◽

Vol 68 (1) ◽

pp. 95-107 ◽

Cited By ~ 4

Author(s):

Szweda Piotr ◽

Zalewska Magdalena ◽

Pilch Joanna ◽

Kot Barbara ◽

Milewski Sławomir

Keyword(s):

Antimicrobial Activity ◽

Essential Oils ◽

Bovine Mastitis ◽

Bactericidal Effect ◽

Dilution Method ◽

Kinetic Assay ◽

Cinnamon Oil ◽

Microtiter Plates ◽

Cure Rates ◽

Time Kill

Abstract Antibiotic therapy of staphylococcal mastitis is characterized by significantly lower cure rates compared to infections caused by other microorganisms. Thus, it is necessary to search for new, alternative, non-antibiotic agents that are effective in the eradication of these bacteria. The aim of our research was to investigate the antimicrobial, especially anti-staphylococcal potential of a large collection (n=36) of essential oils (EOs). Investigation of the antimicrobial activity of tested oils was determined by using a serial, twofold dilution method in 96-wells microtiter plates under conditions recommended by the Clinical and Laboratory Standards Institute (CLSI). The preliminary analysis revealed that six oils, namely: Manuka, Thyme, Geranium, Cedar, Cinnamon (from bark) and Patchouli exhibited the highest activity against reference strains of bacteria. Significant anti-staphylococcal potential of these oils has been also confirmed for a group of 18 Staphylococcus aureus, 8 Staphylococcus epidermidis and 5 Staphylococcus xylosus strains isolated from cases of bovine mastitis. Especially high activity was observed for Cedar, Patchouli, Thyme and Manuka oils. The MIC (Minimal Inhibitory Concentration) values for Patchouli oil were in the concentrations range of 0.01 to 0.313% (v/v). The three other oils inhibited the growth of staphylococci isolated from mastitis in the concentrations range of 0.01 to 0.625% (v/v). Oils isolated from Cinnamomum cassia and Pelargonium graveolens revealed a bit lower, but still satisfactory activity (MIC values in the concentrations range of 0.02 to 1.25% (v/v) and from 0.078 to 1.25% (v/v), respectively). In many cases a slightly higher concentration of oils was required to obtain the bactericidal effect in comparison to growth inhibition. The time – kill kinetic assay revealed that the bactericidal effect was achieved after two hours incubation of the reference strain S. aureus PCM 2051 cells with Thyme oil at concentration equal to 2xMIC (1.25% (v/v)) or MIC (0.625% (v/v)). A slightly lower activity was observed in the case of Cinnamon oil, the bactericidal effect was achieved after 8 hours of incubation. The results of our research clearly indicate that some essential oils exhibit a promising antimicrobial activity and can be considered as alternative antistaphylococcal agents.

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