Resistance Modulation Action, Time-Kill Kinetics Assay, and Inhibition of Biofilm Formation Effects of Plumbagin from Plumbago zeylanica Linn

Antimicrobial resistance (AMR) is a threat to the prevention and treatment of the increasing range of infectious diseases. There is therefore the need for renewed efforts into antimicrobial discovery and development to combat the menace. The antimicrobial activity of plumbagin isolated from roots of Plumbago zeylanica against selected organisms was evaluated for resistance modulation antimicrobial assay, time-kill kinetics assay, and inhibition of biofilm formation. The minimum inhibitory concentrations (MICs) of plumbagin and standard drugs were determined via the broth microdilution method to be 0.5 to 8 μg/mL and 0.25–128 μg/mL, respectively. In the resistance modulation study, MICs of the standard drugs were redetermined in the presence of subinhibitory concentration of plumbagin (4 μg/mL), and plumbagin was found to either potentiate or reduce the activities of these standard drugs with the highest potentiation recorded up to 12-folds for ketoconazole against Candida albicans. Plumbagin was found to be bacteriostatic and fungistatic from the time-kill kinetics study. Plumbagin demonstrated strong inhibition of biofilm formation activity at concentrations of 128, 64, and 32 μg/mL against the test microorganisms compared with ciprofloxacin. Plumbagin has been proved through this study to be a suitable lead compound in antimicrobial resistance drug development.

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8-hydroxyquinoline-5-(N-4-chlorophenyl) sulfonamide and fluconazole combination as a preventive strategy for Candida biofilm in haemodialysis devices

Journal of Medical Microbiology ◽

10.1099/jmm.0.001377 ◽

2021 ◽

Vol 70 (7) ◽

Author(s):

Letícia Fernandes da Rocha ◽

Bruna Pippi ◽

Angélica Rocha Joaquim ◽

Saulo Fernandes de Andrade ◽

Alexandre Meneghello Fuentefria

Keyword(s):

Biofilm Formation ◽

Synergistic Effects ◽

Local Treatment ◽

The Other ◽

Antibiofilm Activity ◽

Preventive Strategy ◽

Clinical Issue ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Time Kill

Introduction. The presence of Candida biofilms in medical devices is a concerning and important clinical issue for haemodialysis patients who require constant use of prosthetic fistulae and catheters. Hypothesis/Gap Statement. This prolonged use increases the risk of candidaemia due to biofilm formation. PH151 and clioquinol are 8-hydroxyquinoline derivatives that have been studied by our group and showed interesting anti-Candida activity. Aim. This study evaluated the biofilm formation capacity of Candida species on polytetrafluoroethylene (PTFE) and polyurethane (PUR) and investigated the synergistic effects between the compounds PH151 and clioquinol and fluconazole, amphotericin B and caspofungin against biofilm cells removed from those materials. Further, the synergistic combination was evaluated in terms of preventing biofilm formation on PTFE and PUR discs. Methodology. Susceptibility testing was performed for planktonic and biofilm cells using the broth microdilution method. The checkerboard method and the time–kill assay were used to evaluate the interactions between antifungal agents. Antibiofilm activity on PTFE and PUR materials was assessed to quantify the prevention of biofilm formation. Results. Candida albicans, Candida glabrata and Candida tropicalis showed ability to form biofilms on both materials. By contrast, Candida parapsilosis did not demonstrate this ability. Synergistic interaction was observed when PH151 was combined with fluconazole in 77.8 % of isolates and this treatment was shown to be concentration- and time-dependent. On the other hand, indifferent interactions were predominantly observed with the other combinations. A reduction in biofilm formation on PUR material of more than 50 % was observed when using PH151 combined with fluconazole. Conclusion. PH151 demonstrated potential as a local treatment for use in a combination therapy approach against Candida biofilm formation on haemodialysis devices.

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Influence of Gallic Acid and Thai Culinary Essential Oils on Antibacterial Activity of Nisin against Streptococcus mutans

Advances in Pharmacological and Pharmaceutical Sciences ◽

10.1155/2021/5539459 ◽

2021 ◽

Vol 2021 ◽

pp. 1-12

Author(s):

Pimsumon Jiamboonsri ◽

Pimpikar Kanchanadumkerng

Keyword(s):

Essential Oils ◽

Gallic Acid ◽

Streptococcus Mutans ◽

Biofilm Formation ◽

Inhibitory Concentration ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Life Threatening ◽

Oral Pathogens ◽

Time Kill

Streptococcus mutans is a well-known oral pathogen commonly associated with a normal dental problem and life-threatening infection. A bacteriocin nisin and the plant-derived compounds including gallic acid (GA) and Thai culinary essential oils (EOs) have been reported to have activity against oral pathogens. However, their synergistic interaction against S. mutans has not been explored. The purposes of this study were primarily to investigate anti-S. mutans properties and the antibiofilm formation of nisin, GA, and five EOs by using the broth microdilution method. Besides, the morphological change, killing rate, and antibacterial synergism were determined by scanning electron microscopy (SEM), time-kill assay, and checkerboard method, respectively. The results demonstrated that kaffir lime leaf (KLL) oil, lemongrass (LG) oil, and GA showed a potent anti-S. mutans activity and inhibited biofilm formation with the possible mechanism targeted on the cell membrane. Additionally, KLL oil revealed anti-S. mutans synergism with GA, LG oil, and chlorhexidine with the fractional inhibitory concentration (FIC) indexes ≤ 0.5. Interestingly, GA displayed a high potential to enhance anti-S. mutans activity of nisin by lowering the minimum inhibitory concentrations (MICs) to at least 8-fold in a bacteriostatic manner. These results suggest that GA and KLL oil may be potentially used as an adjunctive therapy along with nisin and chlorhexidine to control S. mutans infection.

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In VitroSynergistic Effect of Curcumin in Combination with Third Generation Cephalosporins against Bacteria Associated with Infectious Diarrhea

BioMed Research International ◽

10.1155/2014/561456 ◽

2014 ◽

Vol 2014 ◽

pp. 1-8 ◽

Cited By ~ 15

Author(s):

Nishanth Kumar Sasidharan ◽

Sreerag Ravikumar Sreekala ◽

Jubi Jacob ◽

Bala Nambisan

Keyword(s):

Synergistic Effect ◽

New Combination ◽

Normal Fibroblast ◽

Infectious Diarrhea ◽

Combination Drug ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Time Kill ◽

Third Generation Cephalosporins

Diarrhea is one of the leading causes of morbidity and mortality in humans in developed and developing countries. Furthermore, increased resistance to antibiotics has resulted in serious challenges in the treatment of this infectious disease worldwide. Therefore, there exists a need to develop alternative natural or combination drug therapies. The aim of the present study was to investigate the synergistic effect of curcumin-1 in combination with three antibiotics against five diarrhea causing bacteria. The antibacterial activity of curcumin-1 and antibiotics was assessed by the broth microdilution method, checkerboard dilution test, and time-kill assay. Antimicrobial activity of curcumin-1 was observed against all tested strains. The MICs of curcumin-1 against test bacteria ranged from 125 to 1000 μg/mL. In the checkerboard test, curcumin-1 markedly reduced the MICs of the antibiotics cefaclor, cefodizime, and cefotaxime. Significant synergistic effect was recorded by curcumin-1 in combination with cefotaxime. The toxicity of curcumin-1 with and without antibiotics was tested against foreskin (FS) normal fibroblast and no significant cytotoxicity was observed. From our result it is evident that curcumin-1 enhances the antibiotic potentials against diarrhea causing bacteria inin vitrocondition. This study suggested that curcumin-1 in combination with antibiotics could lead to the development of new combination of antibiotics against diarrhea causing bacteria.

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Antimicrobial Resistance in Campylobacter jejuni from Broilers and Broiler House Environments in Norway

Journal of Food Protection ◽

10.4315/0362-028x-70.3.736 ◽

2007 ◽

Vol 70 (3) ◽

pp. 736-738 ◽

Cited By ~ 16

Author(s):

M. NORSTRÖM ◽

G. JOHNSEN ◽

M. HOFSHAGEN ◽

H. THARALDSEN ◽

H. KRUSE

Keyword(s):

Antimicrobial Resistance ◽

Campylobacter Jejuni ◽

Antimicrobial Susceptibility ◽

Antimicrobial Agents ◽

Monitoring Program ◽

Outdoor Environment ◽

Susceptibility Data ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Broiler House

Antimicrobial susceptibility in Campylobacter jejuni collected from the environment outside four broiler houses (n = 63) and from the environment inside these broiler houses (including broiler droppings) (n = 36) from May to September 2004 was studied and compared with isolates from Norwegian broilers analyzed within the frame of the Norwegian monitoring program of antimicrobial resistance in feed, food, and animals (NORM-VET) in 2004 (n = 75). The MICs of oxytetracycline, ampicillin, erythromycin, gentamicin, enrofloxacin, and nalidixic acid were obtained by the broth microdilution method VetMIC. The present study, which to our knowledge is the first Norwegian study on the occurrence of antimicrobial resistance in Campylobacter spp. from the environment of broiler houses, revealed a very low occurrence of antimicrobial resistance in C. jejuni from the broilers and broiler house environments studied. All isolates originating from the four broiler houses studied were susceptible to all the antimicrobial agents tested, except for one isolate from the outdoor environment (courtyard soil), which was resistant to oxytetracycline (MIC, 8 mg/liter). For the isolates from broilers (NORM-VET), low prevalences of resistance to oxytetracycline (1.3%) and ampicillin (4%) were observed. No quinolone resistance was observed. The results for the broiler isolates are in agreement with the earlier findings of a very low prevalence of resistance in Campylobacter from broilers in Norway, which reflects the low usage of antimicrobials in Norwegian broiler production. Furthermore, the present data are in accordance with antimicrobial susceptibility data for C. jejuni from domestically acquired human cases.

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Rosemary and Tea Tree Essential Oils Exert Antibiofilm Activities In Vitro against Staphylococcus aureus and Escherichia coli

Journal of Food Protection ◽

10.4315/0362-028x.jfp-19-337 ◽

2020 ◽

Vol 83 (7) ◽

pp. 1261-1267

Author(s):

TING LIU ◽

JINGFAN WANG ◽

XIAOMAN GONG ◽

XIAOXIA WU ◽

LIU LIU ◽

...

Keyword(s):

Escherichia Coli ◽

Staphylococcus Aureus ◽

Essential Oil ◽

Biofilm Formation ◽

Gas Chromatography Mass Spectrometry ◽

Tea Tree ◽

E Coli ◽

Microdilution Method ◽

Broth Microdilution Method

ABSTRACT The purpose of the present study was to determine the bioactive compounds in rosemary essential oil (REO) and tea tree essential oil (TEO) and to investigate their antibacterial and antibiofilm activities against Staphylococcus aureus and Escherichia coli in vitro. The MIC and MBC assays were performed to assess the antibacterial activity of these two EOs against S. aureus and E. coli with the broth microdilution method. A crystal violet assay was used to ascertain the effects of EOs on the biofilm formation of the test strains, and a tetrazolium bromide (MTT) assay was used to measure the level of inactivation of mature biofilms by EOs. Gas chromatography–mass spectrometry revealed 15 compounds in REO and 27 compounds in TEO, representing 97.78 and 98.13% of the total EO, respectively. Eucalyptol and α-pinene were found in high concentrations in REO, and the two major compounds in TEO were 4-terpineol and terpinolene. The MICs of REO for the two S. aureus and E. coli test strains were both 0.5 mg/mL, and the MICs of TEO for the two strains were both 0.25 mg/mL. Therefore, these EOs can significantly inhibit the formation of biofilms and induced morphological biofilm changes, as verified by scanning electron microscopy. Both EOs had destructive effects on the mature biofilm of the two test strains. TEO was more inhibitory than REO for biofilm formation by the two test strains. HIGHLIGHTS

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Antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis, isolated from blood culture of patients with hematological malignancies during different study periods

Oncohematology ◽

10.17650/1818-8346-2021-16-1-54-63 ◽

2021 ◽

Vol 16 (1) ◽

pp. 54-63

Author(s):

A. V. Fedorova ◽

G. A. Klyasova ◽

I. N. Frolova ◽

S. A. Khrulnova ◽

A. V. Vetokhina ◽

...

Keyword(s):

Antimicrobial Resistance ◽

Blood Culture ◽

Enterococcus Faecalis ◽

Enterococcus Faecium ◽

Dilution Method ◽

Agar Dilution Method ◽

High Susceptibility ◽

Microdilution Method ◽

Broth Microdilution Method ◽

High Level

Objective: to determine antimicrobial resistance of Enterococcus faecium and Enterococcus faecalis isolated from blood culture of hematological patients during different study periods.Materials and methods. Antimicrobial susceptibility of Enterococcus spp., collected as part of the multicenter study was tested by the broth microdilution method (USA Clinical and Laboratory Standards Institute (CLSI), 2018), to daptomycin by Etest (bioMeriéux, France). High-level gentamicin resistance (HLGR) and high-level streptomycin resistance (HLSR) was performed by the agar dilution method (CLSI (Oxoid, UK), 2018).Results. The susceptibility of 366 E. faecium (157 in 2002-2009 and 209 in 2010-2017) and 86 E. faecalis (44 in 20022009 and 42 in 2010-2017) was studied. In the second study period (2010-2017) the rise of vancomycin-resistant E. faecium (VREF) increased from 8.3 % to 23.4 % (p = 0.0001), and two linezolid-resistant (LREF) were identified. All VREF and LREF remained susceptible to daptomycin and tigecycline. The rate of susceptible to tetracycline E. faecium remained the same (73.9 and 74.6 %), and an increase in susceptibility to chloramphenicol (74.5 and 82.3 %) was observed. Susceptibility of E. faecium to tetracycline was detected with almost the same rate and in a part of isolates, the increase of susceptibility to chloramphenicol was registered during the analyzed periods. The rise of E. faecium susceptible to HLGR and HLSR has increased significantly in 2010-2017 compared to 2002-2009. Erythromycin, levofloxacin, ampicillin and penicillin had the least activity against E. faecium (less than 5 %).All E. faecalis were susceptible to tigecycline, linezolid, and teicoplanin. Only one of E. faecalis had intermediate resistance to vancomycin. High susceptibility to ampicillin in E. faecalis remained unchanged (97.7 and 97.6 %, respectively). In the second period of the study the rise of susceptible E. faecalis decreased significantly to penicillin (from 97.7 % to 76.2 %), to levofloxacin (from 59.1 % to 31 %), to HLSR (from 52.3 % до 31 %), and to HLGR (from 47.7 % to 26.2 %), remained unchanged to chloramphenicol (52.3 % and 50 %) and was minimal to erythromycin and tetracycline.Conclusion. The study demonstrated higher rates of antibiotic resistance among E. faecium, which consisted of an increase in VREF and the appearance of linezolid-resistant strains. High susceptibility to ampicillin remained in E. faecalis, but there was an increase in resistance to penicillin and aminoglycosides.

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Chemical Composition, and Evaluation of Antibacterial，Antibiofilm and Synergistic Effects with Conventional Antibiotics of Essential Oil from Mallotus repandus

Records of Natural Products ◽

10.25135/rnp.217.20.10.1854 ◽

2021 ◽

Vol 15 (4) ◽

pp. 324-329

Author(s):

Pengxiang Lai ◽

Xin-Chen Zhang ◽

Lin Zhu ◽

Xin-Yu Li ◽

Li-Chuan Liu

Keyword(s):

Essential Oil ◽

Biofilm Formation ◽

Synergistic Effects ◽

Antibacterial Properties ◽

Good Alternative ◽

Bactericidal Effect ◽

Bacterial Strains ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Mallotus Repandus

The essential oil (EO) of aerial parts of Mallotus repandus (Willd.) Muell. Arg. was extracted by hydrodistillation and characterized by GC/FID and GC/MS. Fifty-one compounds comprising 97.1% of the EO were identified, of which α-humulene (18.7%), β-selinene (12.8%), aciphyllene (10.7%), (E)-caryophyllene (8.4%), α-copaene (5.5%), humulene epoxide II (4.9%) and caryophyllene oxide (4.3%) were the major compounds. The EO was evaluated for antibacterial properties using broth microdilution method and crystal-violet static biofilm formation assay. The M. repandus EO possessed a bactericidal effect against tested gram-positive bacteria strains (MIC = MBC: 0.05-0.10 mg/mL). Further, the EO showed the ability to inhibit the biofilm formation of Staphylococcus aureus. In addition, the potential synergistic effect was assessed by checkerboard method. Combination of the M. repandus EO with Streptomycin showed synergistic effects against the tested bacterial strains. This study demonstrates that M. repandus EO could be further explored as good alternative for potential pharmaceuticals.

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Major Bloodstream Infection-Causing Bacterial Pathogens and Their Antimicrobial Resistance in South Korea, 2017–2019: Phase I Report From Kor-GLASS

Frontiers in Microbiology ◽

10.3389/fmicb.2021.799084 ◽

2022 ◽

Vol 12 ◽

Author(s):

Dokyun Kim ◽

Eun-Jeong Yoon ◽

Jun Sung Hong ◽

Min Hyuk Choi ◽

Hyun Soo Kim ◽

...

Keyword(s):

Antimicrobial Resistance ◽

Phase I ◽

Bloodstream Infection ◽

Molecular Mechanisms ◽

Diffusion Method ◽

Disk Diffusion Method ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Glass Target ◽

Blood Specimens

To monitor national antimicrobial resistance (AMR), the Korea Global AMR Surveillance System (Kor-GLASS) was established. This study analyzed bloodstream infection (BSI) cases from Kor-GLASS phase I from January 2017 to December 2019. Nine non-duplicated Kor-GLASS target pathogens, including Staphylococcus aureus, Enterococcus faecalis, Enterococcus faecium, Streptococcus pneumoniae, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter spp., and Salmonella spp., were isolated from blood specimens from eight sentinel hospitals. Antimicrobial susceptibility testing, AMR genotyping, and strain typing were carried out. Among the 20,041 BSI cases, 15,171 cases were caused by one of the target pathogens, and 12,578 blood isolates were collected for the study. Half (1,059/2,134) of S. aureus isolates were resistant to cefoxitin, and 38.1% (333/873) of E. faecium isolates were resistant to vancomycin. Beta-lactamase-non-producing ampicillin-resistant and penicillin-resistant E. faecalis isolates by disk diffusion method were identified, but the isolates were confirmed as ampicillin-susceptible by broth microdilution method. Among E. coli, an increasing number of isolates carried the blaCTX–M–27 gene, and the ertapenem resistance in 1.4% (30/2,110) of K. pneumoniae isolates was mostly (23/30) conferred by K. pneumoniae carbapenemases. A quarter (108/488) of P. aeruginosa isolates were resistant to meropenem, and 30.5% (33/108) of those carried acquired carbapenemase genes. Over 90% (542/599) of A. baumannii isolates were imipenem-resistant, and all except one harbored the blaOXA–23 gene. Kor-GLASS provided comprehensive AMR surveillance data, and the defined molecular mechanisms of resistance helped us to better understand AMR epidemiology. Comparative analysis with other GLASS-enrolled countries is possible owing to the harmonized system provided by GLASS.

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Synergistic Antibiofilm Efficacy of Thymol and Piperine in Combination with Three Aminoglycoside Antibiotics against Klebsiella pneumoniae Biofilms

Canadian Journal of Infectious Diseases and Medical Microbiology ◽

10.1155/2021/7029944 ◽

2021 ◽

Vol 2021 ◽

pp. 1-8

Author(s):

Borel Bisso Ndezo ◽

Christian Ramsès Tokam Kuaté ◽

Jean Paul Dzoyem

Keyword(s):

Klebsiella Pneumoniae ◽

Biofilm Formation ◽

Inhibitory Concentration ◽

Alternative Therapy ◽

Aminoglycoside Antibiotics ◽

Antibiofilm Activity ◽

Promising Alternative ◽

Microdilution Method ◽

Fold Reduction ◽

Broth Microdilution Method

Background. Thymol and piperine are two naturally occurring bioactive compounds with several pharmacological activities. In this study, their antibiofilm potential either alone or in combination with three aminoglycoside antibiotics was evaluated against a biofilm of Klebsiella pneumoniae. Methods. Determination of antimicrobial susceptibility was performed using the broth microdilution method. Biofilm formation was evaluated by the microtiter plate method. Antibiofilm activity was determined using 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium-bromide (MTT) assay. The combination studies were performed by the checkerboard microdilution method. Results. The minimum biofilm inhibitory concentration (MBIC) of streptomycin was reduced by 16- to 64-fold when used in combination with thymol, while the MBIC of kanamycin was reduced by 4-fold when combined with piperine. The minimum biofilm eradication concentration (MBEC) values of streptomycin, amikacin, and kanamycin were, respectively, 16- to 128-fold, 4- to 128-fold, and 8- to 256-fold higher than the planktonic minimum inhibitory concentration (MIC). Thymol combined with streptomycin or kanamycin showed synergic effects against the preformed biofilm with 16- to 64-fold reduction in the minimum biofilm eradication concentration values of each antibiotic in combination. Piperine acted also synergically with kanamycin with an 8- to 16-fold reduction in the minimum biofilm eradication concentration values of kanamycin in combination. Conclusion. The association of thymol with antibiotics showed a strong synergistic effect both in the inhibition of biofilm formation and the destruction of the preformed biofilm of K. pneumoniae. This study suggests that a combination of thymol with streptomycin, amikacin, or kanamycin could be a promising alternative therapy to overcome the problem of K. pneumoniae biofilm-associated infections.

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Evaluation of the in vitro interaction of fosfomycin and meropenem against metallo-β-lactamase–producing Pseudomonas aeruginosa using Etest and time-kill assay

Journal of Investigative Medicine ◽

10.1136/jim-2020-001573 ◽

2020 ◽

pp. jim-2020-001573

Author(s):

Sanjida Jahan ◽

Heather Davis ◽

Deborah S Ashcraft ◽

George A Pankey

Keyword(s):

Pseudomonas Aeruginosa ◽

Inhibitory Concentration ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Microdilution Method ◽

Broth Microdilution Method ◽

Time Kill ◽

In Vitro Interaction ◽

Antimicrobial Combinations

Pseudomonas aeruginosa is a nosocomial pathogen containing various resistance mechanisms. Among them, metallo-β-lactamase (MBL)–producing Pseudomonas are difficult to treat. Fosfomycin is an older antibiotic that has recently seen increased usage due to its activity against a broad spectrum of multidrug-resistant organisms. Our aim was to evaluate the combination of fosfomycin and meropenem against 20 MBL-producing P. aeruginosa (100% meropenem-resistant and 20% fosfomycin-resistant) using both an Etest minimal inhibitory concentration (MIC): MIC method and time-kill assay. MICs for fosfomycin and meropenem were determined by Etest and by broth microdilution method for the latter. The combination demonstrated synergy by Etest in 3/20 (15%) isolates and 5/20 (25%) isolates by time-kill assay. Results from the Etest method and time-kill assay were in agreement for 14/20 (70%) of isolates. No antagonism was found. Comparing both methods, Etest MIC: MIC method may be useful to rapidly evaluate other antimicrobial combinations.

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