Indifferent Effect Research Articles

Propolis polyphenolic compounds affect the viability and structure of Helicobacter pylori in vitro

To evaluate the anti-Helicobacter pylori activity of the major polyphenol compounds of propolis and their cellular damage, both as single molecule or in combination. Honey bees propolis were fractionated by using CPC and preparative HPLC. Four major polyphenols (chrysin, pinocembrin, galangin and caffeic acid phenethyl ester) were identified by thin layer chromatography–mass spectroscopy and liquid chromatography–mass spectroscopy. These compounds inhibited both ATCC and clinical H. pylori strains, with caffeic acid phenethyl ester being the most active. The four compounds presented minimum inhibitory concentration in the range 256–1024μgml−1 and a fractional inhibitory concentration of 64–512μgml−1. In mixtures all compounds showed an indifference effect (FIC<0.15) but chrysin+galangin which was synergistic (FIC=2.0). Killing curves show a similar behavior as the antibiotic amoxycillin. On the other hand, analyses by transmission electron microscopy at sub inhibitory concentration show vesicle formation and cell lysis after exposition to both individual polyphenol compounds and in mixture. The major compounds of propolis show anti-H. pylori activity both as individual compounds and in mixture. When combined they present mainly indifference but exert a lytic activity upon H. pylori, suggesting a potential bactericidal activity of propolis.

Uji Aktivitas Antibakteri Kombinasi Minyak Atsiri Biji Ketumbar (Coriandrum sativum L.) dan Gentamisin terhadap Staphylococcus epidermidis

&#x0D; Gentamicin is one of the antibiotics from the aminoglycoside group used for the treatment of infections. Gentamicin has side effect such as permanent ototoxicity and reversible nephrotoxicity. It was necessary to reduce these effects by combining antibiotic with natural ingredients, one of those is coriander seeds essential oil. Combination therapy is done to reduce the potential side effects, and increase antibacterial efficacy. Antibacterial activity test were conducted to measure the MIC values of gentamicin, essential oils of coriander seeds, and combination of both. Based on the antibacterial activity test, MIC value of gentamicin was 4 µg/mL, coriander seed essential oil was 50 µg/mL and MIC combination of gentamicin and essential oil of coriander seeds were 0.5 µg/mL and 50 µg/mL. The FIC Index value obtained was 1.125 meaning that the combination effect was indifferent. Indifferent combination effect means the use of a combination of coriander seeds essential oil and gentamicin as antibacterial was not better than the single use.&#x0D; &#x0D; Keywords: coriander, essential oil, antibacterial, FIC Index, S. epidermidis&#x0D;

Synergistic Activities of Colistin with Tigecycline Combination Against Clinical Isolates of Carbapenem-resistant Acinetobacter baumannii

OBJECTIVES: To determine in vitro antimicrobial susceptibility and synergistic activity of colistin in combination with tigecycline against clinical strains of carbapenem- resistant Acinetobacter baumannii (CRAB).MATERIAL AND METHODS: Colistin and tigecycline minimum inhibitory concentrations (MICs) of 12-clinical CRAB isolates were determined by broth microdilution. Checkerboard testing was performed to assess the interaction of the colistin-tigecycline combination. Fractional inhibitory concentration indexes (ΣFIC) in the range of 0.5 to 1.0, &gt; 1.0 to &lt; 4.0 and ≥ 4.0 are considered as additive, indifferent, and antagonistic effects, respectively.RESULTS: All CRAB isolates were susceptible to colistin. Three out of 12 CRABs were susceptible to tigecycline based on a pharmacokinetic-pharmacodynamics (PK-PD) breakpoint (MICs ≤ 0.25 μg/mL). The MIC of both antimicrobials was decreased in most of the CRAB isolates in the checkerboard synergy testing. The interaction of colistin and tigecycline combination revealed both additive and indifferent effects in five and seven of the 12-CRAB isolates, respectively. Neither synergism nor antagonism of colistin and tigecycline combination was demonstrated.CONCLUSION: No synergistic effect between colistin and tigecycline against CRAB isolates was detected. However, the combination of these two drugs is likely to result in a decrease in the MIC of both drugs. Further studies with a larger sample to determine the in vitro synergistic activity of colistin and tigecycline combination are required.

Synergistic Activities of Colistin with Tigecycline Combination Against Clinical Isolates of Carbapenemresistant Acinetobacter baumannii

OBJECTIVES: To determine in vitro antimicrobial susceptibility and synergistic activity of colistin in combination with tigecycline against clinical strains of carbapenem- resistant Acinetobacter baumannii (CRAB). MATERIAL AND METHODS: Colistin and tigecycline minimum inhibitory concentrations (MICs) of 12-clinical CRAB isolates were determined by broth microdilution. Checkerboard testing was performed to assess the interaction of the colistin-tigecycline combination. Fractional inhibitory concentration indexes (ΣFIC) in the range of 0.5 to 1.0, > 1.0 to < 4.0 and ≥ 4.0 are considered as additive, indifferent, and antagonistic effects, respectively. RESULTS: All CRAB isolates were susceptible to colistin. Three out of 12 CRABs were susceptible to tigecycline based on a pharmacokinetic-pharmacodynamics (PK-PD) breakpoint (MICs ≤ 0.25 μg/mL). The MIC of both antimicrobials was decreased in most of the CRAB isolates in the checkerboard synergy testing. The interaction of colistin and tigecycline combination revealed both additive and indifferent effects in five and seven of the 12-CRAB isolates, respectively. Neither synergism nor antagonism of colistin and tigecycline combination was demonstrated. CONCLUSION: No synergistic effect between colistin and tigecycline against CRAB isolates was detected. However, the combination of these two drugs is likely to result in a decrease in the MIC of both drugs. Further studies with a larger sample to determine the in vitro synergistic activity of colistin and tigecycline combination are required. Keywords: in vitro, synergism, tigecycline, colistin, checkerboard method DOI: 10.31524/bkkmedj.2019.02.005

Interactions between Clotrimazole and selected essential oils against Malassezia pachydermatis clinical isolates.

The aim of this study was to investigate interactions between conventional antifungal drug and essential oils against isolates of Malassezia pachydermatis. Antifungal activity of Cinnamomum cassia, Melaleuca alternifolia, Mentha piperita, Origanum vulgare and Syzygium aromaticum essential oils were tested against 19 strains of M. pachydermatis isolated from healthy dogs and reference strain M. pachydermatis CBS 1879. The checkerboard assay was used to search for in- teractions. Synergism was observed for the combination of clotrimazole with Melaleuca alternifolia essential oil, Mentha piperita and Origanum vulgare. The combinations of Cinnamomum cassia and Syzygium aromaticum essential oils with clotrimazole showed indifferent effect. Additive antimicrobial activity was observed for the combination of clotrimazole with Syzygium aromaticum and Melaleuca alternifolia essential oils against reference strain. The obtained results showed synergistic interactions between essential oils and clotrimazole which could improve effectiveness of this antifungal drug.

ANTI-CANDIDA ALBICANS ACTIVITY OF THE ASSOCIATION OF CITRONELAL WITH ANFOTERICIN B OR WITH CETOCONAZOLE

Fungal infections caused by species of the genus Candida are responsible for high morbidity and mortality rates, mainly affecting immunocompromised individuals. Among fungi, Candida albicans is the most frequently isolated species of clinical specimens. A problem associated with increased resistance of pathogenic fungi to the agents used in the therapeutic regimen and the limited number of drugs to cure these infections. As a result, the search for new drugs with antifungal activity has become increasingly important. The aim of this study is to study the antifungal activity of citronellal alone and in combination with amphotericin B or ketoconazole. The Minimal Inhibitory Concentration of citronellal, amphotericin B and ketoconazole against strains of Candida albicans were evaluated by the microdilution technique, and the Minimum Fungicide Concentration of citronellal against the same strains was also performed. Through the checkerboard methodology the effect of the combination of citronelal with amphotericin B or with ketoconazole was determined. This study showed that the association of citronellal with ketoconazole was shown to be an additive against one of the strains of C. albicans and indifferent to another strain. While the combined activity of citronellal and amphotericin B demonstrated an indifferent effect on the strains tested.

Paromomycin production from Streptomyces rimosus NRRL 2455: statistical optimization and new synergistic antibiotic combinations against multidrug resistant pathogens

BackgroundResponse surface methodology (RSM) employing Box-Behnken design was used to optimize the environmental factors for the production of paromomycin, a 2 deoxystreptamine aminocyclitol aminoglycoside antibiotic, (2DOS-ACAGA) from Streptomyces (S.) rimosus NRRL 2455. Emergence of bacterial resistance caught our attention to consider the combination of antimicrobial agents. The effect of paromomycin combination with other antimicrobial agents was tested on some multiple drug resistant isolates. To the best of our knowledge, this is the first report on optimization of paromomycin production from S. rimosus NRRL 2455. A Quadratic model and response surface method were used by choosing three model factors; pH, incubation time and inoculum size. A total of 17 experiments were done and the response of each experiment was recorded. Concerning the effect of combining paromomycin with different antimicrobial agents, it was tested using the checkerboard assay against six multidrug resistant (MDR) pathogens including; Pseudomonas (P.) aeruginosa (2 isolates), Klebsiella (K.) pneumoniae, Escherichia (E.) coli, methicillin sensitive Staphylococcus aureus (MSSA) and methicillin resistant Staphylococcus aureus (MRSA). Paromomycin was tested in combination with ceftriaxone, ciprofloxacin, ampicillin/sulbactam, azithromycin, clindamycin and doxycycline.ResultsThe optimum conditions for paromomycin production were a pH of 6, an incubation time of 8.5 days and an inoculum size of 5.5% v/v using the optimized media (soybean meal 30 g/L, NH4CL 4 g/L, CaCO3 5 g/L and glycerol 40 ml/L), 28 °C incubation temperature, and 200 rpm agitation rate that resulted in 14 fold increase in paromomycin production as compared to preliminary fermentation level using the basal medium. The tested antibiotic combinations showed either synergistic effect on paromomycin activity on most of the tested MDR pathogens (45.83%), additive effect in 41.67% or indifferent effect in 12.5%.ConclusionRSM using multifactorial design was a helpful and a reliable method for paromomycin production. Paromomycin combination with ceftriaxone, ciprofloxacin, ampicillin/sulbactam, azithromycin, clindamycin or doxycycline showed mostly synergistic effect on certain selected clinically important MDR pathogens.

AN ANALYSIS OF GREEN BUILDING COSTS USING A MINIMUM COST CONCEPT

Green buildings are known for yielding a better indoor habitat, saving energy and protecting the environment. However, they require greater investment than conventional buildings. Green buildings can be classified at different levels ranging through certified, silver, gold and platinum. The classification chosen is likely to affect project costs. Adopting a platinum level of green building specifications tends to incur the highest project costs. While with gold, silver and certified levels expenditure will be reduced accordingly. The actual degree of project cost differences also depends on additional factors, such as site location, design specifications, construction condition, material and equipment selection and LEED consultant expertise. Construction budgeting represents a crucial factor for project owners developing green buildings. This research presents a method for determining the minimum project costs of green building developments. The processes and steps to be completed in determining such minimum project costs are presented based on a case study of a learning centre building which received LEED platinum certification. It was found that choosing certified and silver levels has an indifferent effect on project costs, whereas expenditure increases exponentially with gold and platinum levels of certification.

Strategic CSR for airlines: does materiality matter?

PurposeConsidering the increasing significance of corporate social responsibility (CSR) in the corporate world and the mixed findings of the financial implication of CSR investment in the financial economics literature, the purpose of this study is to examine the relationship between (im)material CSR investment and firm performance and the moderating role of airline type and economic conditions based on the stakeholder theory and institutional pressure argument.Design/methodology/approachThis study uses a two-way random-effects model by firm and year along with using clustering coefficient estimation by firm to control for the possibility of inflated standard errors because of autocorrelation across years within a given firm.FindingsThis study finds that both material and immaterial CSR initiatives do not directly influence firm performance, but airline type and economic conditions do moderate the relationship. In specific, the study found that airlines’ investments in material CSR initiatives show an indifferent effect on firm performance between low-cost and full-service carriers and also between non-recessionary and recessionary periods. On the other hand, investments in immaterial CSR initiatives present different impacts on firm performance between low-cost and full-service carriers and between non-recessionary and recessionary periods. In details, the effect is more negative for low-cost carriers and recessionary periods than full-service carriers and non-recessionary periods.Originality/valueThis is the first empirical investigation of materiality for the airline industry in relation to firm performance using the industry-specific Materiality Map developed by the Sustainability Accounting Standards Board. Further, this study incorporates two additional moderators (airline type and economic conditions) to enhance the understanding of the proposed relationships between (im)material CSR and firm performance.

Detection of Synergistic Antimicrobial Activities of Ceftaroline, Telavancin, Daptomycin, and Vancomycin Against Methicillin-Resistant Staphylococcus aureus Strains in Intensive Care Units

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a leading pathogen of serious infectious diseases in intensive care units. Novel antibiotic combination therapies are needed to treat serious infectious diseases caused by MRSA. Objectives: Our objective was to evaluate the minimum inhibitory concentrations (MICs) of ceftaroline (CPT), telavancin (TLV), daptomycin (DPC), and vancomycin (VA) alone and in vitro synergistic activity of CPT-TLV, CPT-DPC, and CPT-VA combinations against MRSA isolates. Methods: Fifty MRSA strains isolated from blood (90%) and tracheal aspirate (10%) of patients in intensive care units (ICUs) between 2013 and 2016 were included in the study. The Epsilometer test was used for determining the synergistic activities of antibiotic combinations. We evaluated the synergistic, additive, indifferent, and antagonist effects of MRSA strains by the fractional inhibitory concentration (FIC) index. Results: Of the 50 MRSA strains tested, 100% were susceptible to TLV, DPC, and VA. CPT was detected as resistant in 3 (6%) of the isolates. CPT-TLV, CPT-DPC, and CPT-VA combinations were found to have synergistic effects in 14%, 38%, 10% and additive effects in 40%, 32%, and 22% of the isolates, respectively. No antagonism was detected in any of the combinations. Conclusions: The combination of CPT with DPC showed the best synergy profile among all antibiotic combinations tested against MRSA isolates obtained from patients in ICUs.

Trainees‘ Influence on Adenoma Detection and Follow-Up Recommendations at Screening and Surveillance Colonoscopies

Introduction: Background: Colonoscopy has emerged as the main diagnostic and therapeutic tool in the detection of colonic adenomas. Training future endoscopists is essential to meet future demands. Objectives: Studies have shown some what conflicting results regarding the influence of trainee-participation on adenoma detection rates (ADR), mostly showing positive or indifferent effects of trainee participation. A previous prospective study by our group showed no adverse effect of trainee participation on ADR. However, this study did not include first year trainees or subsequent surveillance exams. The aim of the current investigation was to see, whether the inclusion of first year trainees magnifies the noted difference and whether trainee participation affects ADRs or the timing of subsequent surveillance exams Methods: A retrospective analysis of average-risk screening colonoscopies over a 3-year interval was performed.Patients with poor preparation were excluded.The final analysis included 4922 screening colonoscopies between the years 2004-2006, as well as 2184 subsequent surveillance exams. Data were collected from pathologic and endoscopic electronic data bases. The primary outcome was the ADR at colonoscopies with and without trainee participation Results: Trainees participated in 1131 (23%) screening exams and in 232 (11%) surveillance exams. ADR did not significantly differ (P=0.19) for screening exams with trainee participation (19.5%) or those without (21.4%). ADRs were generally higher at surveillance exams, both with (22.4%) and without (27.5%) trainee participation. The noted difference of ADRs at surveillance colonoscopies with or without trainee participation did not reach statistical significance (P=0.1). Multivariate analysis showed no influence of first year fellow participation on the outcome. When surveillance recommendations differed from guidelines, shorter surveillance intervals were given more frequently if trainees participated during the initial screening procedure (P=0.0001). Conclusion: Limitations: Single-center, retrospective study. Conclusions: ADR did not significantly differ at screening or surveillance colonoscopies with or without trainee participation. There was a trend towards higher ADR at surveillance exams in both groups. The inclusion of first year trainees had no adverse effect on the outcome. However, trainee participation may result in shortened surveillance recommendations after initial screening exams.305_A Figure 1. Pre-Test and Post-Test

In vitro antibiotic effects of drug combinations against colistin-heteroresistant Acinetobacter baumannii

Objective To evaluate the in vitro antibiotic effects of colistin combined with meropenem, levofloxacin or fosfomycin against colistin-heteroresistant Acinetobacter baumannii (A.baumannii). Methods A total of 576 A. baumannii clinical isolates were collected from the First Affiliated Hospital of Wenzhou Medical University from 2014 to 2015. Minimal inhibitory concentrations (MICs) of colistin against A. baumannii were detected by broth dilution method. Colistin-heteroresistant A. baumannii isolates were screened using population analysis profiles (PAPs). MICs of colistin combined with meropenem, levofloxacin or fosfomycin, and the four drugs used alone against colistin-heteroresistant A. baumannii were detected by checkerboard method and broth dilution method. Fractional inhibitory concentration index (FICI) was calculated to evaluate antibiotic effects. Results None of the 576 A. baumannii isolates was resistant to colistin as indicated by the broth dilution method. Nine colistin-heteroresistant A. baumannii isolates were identified using PAPs. Compared with the MICs of colistin used alone, the MICs of colistin used in combination with meropenem, levofloxacin or fosfomycin against colistin-heteroresistant isolates were all decreased. Colistin-meropenem combination showed synergistic (55.6%), additive (33.3%) and indifferent effects (11.1%), but no antagonistic effect. Colistin-levofloxacin combination showed synergistic (55.6%), additive (22.2%) and indifferent effects (22.2%), but no antagonistic effect. Colistin-fosfomycin combination showed synergistic (77.8%) and additive (22.2%) effects, but no indifferent or antagonistic effect. Conclusion In vitro use of colistin in combination with meropenem, levofloxacin or fosfomycin has synergistic and additive antibacterial effects against colistin-heteroresistant A. baumannii. Combinations of colistin-meropenem and colistin-levofloxacin have fewer indifferent effects and no antagonistic effect. Key words: Colistin; Heteroresistance; Acinetobacter baumannii; Drug combination

Onion and Garlic Extracts Potentiate the Efficacy of Conventional Antibiotics against Standard and Clinical Bacterial Isolates.

Onion (Allium cepa L.) and garlic (Allium sativum L.) extracts are traditionally used in many cultures as antimicrobial agents. Nonetheless, there is still a dearth of scientific validation pertaining to the antibacterial and possible antibiotic potentiating activity of these plants. Decoction as traditionally used and methanol, ethanol, ethyl acetate, and acetone extracts of onion and garlic were evaluated for their antibacterial activity against 15 bacterial strains (6 ATCC strains and 9 clinical isolates) using the broth microdilution method to establish the minimum inhibitory concentration. The bacteriostatic and bactericidal actions were determined as compared to conventional antibiotics (streptomycin and chloramphenicol). Fractional Inhibitory Concentration (FIC) was determined to establish any synergistic interaction between the extracts and antibiotics using a modified checkerboard assay. The ethyl acetate extract of garlic showed bactericidal effect against 1 ATCC (E. coli) and 2 clinical isolates. Streptomycin produced only indifferent effect (FIC 1< and ≤ 4) when combined with ethyl acetate extract of onion. Chloramphenicol showed synergism with ethyl acetate extract of onion against ATCC S. aureus (FIC 0.27-0.30) and Micrococci species (FIC 0.27-0.32). Streptomycin showed mostly antagonism whereas chloramphenicol showed synergism effects with the ethyl acetate extract of garlic. The observed antibacterial activity might be justified due to the presence of high concentration of phenolic compounds in the extracts. This study has provided an opportunity to establish valuable baseline information on the antibiotic potentiating activity of onion and garlic which can be further exploited for the treatment and/or management of infectious diseases.

Parental Indifference and Children’s Digital Piracy in South Korea: Mediation Effects of Low Self-Control and Misconception

Digital piracy is a global concern for society. Although adolescents’ digital piracy in South Korea is pervasive, its cause has rarely been examined. Using data collected by the Korean Institute of Criminology (KIC) in 2009, this study conducted structural equation modeling to determine if low self-control and social learning theory accounted for digital piracy. This study found that parental indifference increased adolescents’ digital piracy through low self-control and misconception about digital piracy. However, there were no direct effects of parental indifference on the digital piracy behaviors. In particular, the mediation effect in the model combining low self-control and misconception was greater compared to other models. Overall, the combination of low self-control and social learning theory provided a more meaningful framework to explain adolescents’ digital piracy. Results of this study can offer ways to aid in the examination and remediation of this particular form of deviant behaviors on the Internet by adolescents.

Evaluation of the selective antibacterial activity of Eucalyptus globulus and Pimenta pseudocaryophyllus essential oils individually and in combination on Enterococcus faecalis and Lactobacillus rhamnosus.

Essential oils (EOs), as substitutes for antibiotics in animal diets, should have selective antibacterial activity between pathogenic and beneficial bacteria from the animal gut. Thus, this study evaluated the selective antibacterial activity of Eucalyptus globulus (EG) and Pimenta pseudocaryophyllus (PP) EOs on Enterococcus faecalis as a surrogate model of pathogenic bacterium and on Lactobacillus rhamnosus as a beneficial bacterium model. The EOs antibacterial activity was evaluated by determination of minimal inhibitory concentrations (MICs), minimal bactericidal concentration (MBCs), and fractional inhibitory concentration (FIC) indices. The time-kill and sequential exposure assays were also performed, but using only the EG oil, which was the best selective EO, since it had a MIC lower on E. faecalis (7.4 mg/mL) than on L. rhamnosus (14.8 mg/mL). FIC index values showed that the combination of the two EOs had an indifferent effect (1.25 and 2.03) on E. faecalis and an additive effect (1.00) on L. rhamnosus. The time-kill assay showed that EG oil was able to kill E. faecalis within 15 min of treatment (∼5 log reduction) and caused a reduction ∼3 log of L. rhamnosus viability. The sequential exposure assay showed that EG oil (at MIC/2) produced higher reduction on E. faecalis viability (∼3 log) than on L. rhamnosus (∼2 log) as well. Therefore, L. rhamnosus presented higher tolerance to the antibacterial activity of EG oil than E. faecalis did.

Combination Effects of Cymbopogon sp. Essential Oil on Selected Bacteria

Combination effects between Cymbopogon flexuosus and Cymbopogon nardus essential oils were studied to determine whether the combination could emerge as better and more powerful antimicrobial agents against six selected bacteria includes Bacillus subtilis, Escherichia coli, Salmonella typhimurium, Serratia marcescens, Staphylococcus aureus, and Staphylococcus epidermidis. This combination study exhibited 40.67% additive, 28.67% antagonistic, 16.00% indifferent and 14.66% synergistic effects. C. flexuosus and C. nardus essential oils in combination showed a high inhibitory activity against S. aureus with 16% synergistic, 64% additive and 20% indifferent effects.

In-Vitro Activity of Doxycycline and β-Lactam Combinations Against Different Strains of Burkholderia pseudomallei.

Although doxycycline is active against Burkholderia pseudomallei and has been used in the eradication stage of melioidosis therapy, it is not regularly used during the initial intensive phase. In order to assess its potential use in intensive phase therapy, we investigated in vitro pharmacodynamic activity of doxycycline and β-lactams alone and in combination against four Malaysian strains of B. pseudomallei. Using a checkerboard assay, the combinations of doxycycline and imipenem, doxycycline and ceftazidime, and doxycycline and amoxicillin-clavulanate tested against four strains showed indifferent effects with summation fractional inhibitory concentration values ranging from 0.62 to 2.12. Time-kill experiments also indicated that the combinations of doxycycline/β-lactam antibiotics against four tested strains did not fulfil synergy criteria, in which all combinations showed indifferent effects with -1.36 to 1.26-log CFU/mL compared to the most active monotherapy regimen in each combination. No re-growth of bacteria was detected after the early killing in doxycycline/β-lactam combination regimens compared to β-lactam monotherapy regimens, in which 9 out of 10 were associated with re-growth of bacteria. As no synergistic activity was observed, this in vitro study showed that doxycycline offers no additional benefit to be used in combination with β-lactams in the intensive phase of therapy.

INTERACTION EFFECTS OF LITSEA CUBEBA ESSENTIAL OIL AND ANTIBIOTICS ON ANTIBACTERIAL ACTIVITY AGAINST PATHOGENIC BACTERIA IN AQUACULTURE

In this study, the interaction effects of Litsea cubeba essential oil (EO) and two antibiotics (ABs) on the antibacterial activity against pathogenic bacteria in aquaculture were investigated. Two reference strains (Escherichia coli ATCC 25922 (E. coli ATCC 25922) and Vibrio parahaemolyticus ATCC 17802 (V. parahaemolyticus ATCC 17802)) and six locally isolated aquatic pathogenic strains (E. coli 9C48, E. coli 11C123, Vibrio 2S4, Vibrio 2N38, V. parahaemolyticus ND201 and V. parahaemolyticus TB81) were used. The inhibitory effects of individual antimicrobial agent (L. cubeba EO, nalidixic acid, and oxytetracycline) were tested against eight strains by using broth microdilution assay in 96-well microplates. A higher inhibitory effect of L. cubeba EO was observed against isolated aquatic pathogenic (MIC = 1.15 - 2.30 mg/mL) than that in the reference strains (MIC = 5.53 mg/mL). The combination effects of L. cubeba EO and ABs often used in the treatment of bacteria effects in aquaculture (nalidixic acid and oxytetracycline) were evaluated by the checkerboard method. Fractional Inhibitory Concentration (FIC) values were determined to characterize the interaction among combinations. Out of 16 AB-EO combinations tested, 11 of them showed a synergistic effect (FIC ≤ 0.5), 3 of them showed an additional effect (0.5 &lt; FIC ≤ 1.0) and 2 of them showed indifferent effect (1 &lt; FIC ≤ 4), no antagonistic effect was observed. The antimicrobial synergy of EO and AB could enhance efficacy, reduce toxicity, decrease adverse side effects, and lower the dose of ABs used in aquaculture.

Cymbopogon citratus and Cymbopogon giganteus essential oils have cytotoxic effects on tumor cell cultures. Identification of citral as a new putative anti-proliferative molecule

Cymbopogon species are used as traditional remedies in Burkina Faso for treating several diseases. We aimed to study the effects of their essential oils on cancer cell lines. For that purpose, Cymbopogon citratus (DC.) Stapf. and Cymbopogon giganteus Chiov. were studied for their essential oils after various chemical extractions. Antioxidant, potential anti-inflammatory action (inhibition of lipoxygenase) and cytotoxic activities were also tested on various prostate cancer and glioblastoma cell lines. Thirty-three compounds were identified in the essential oil of C. giganteus: Limonene (19.33%), Mentha-1(7),8-dien-2-ol cis (17.34%), Mentha-1(7),8-dien-2-ol trans (13.95%), trans-Mentha-2,8-diene-para-ol 1 (13.91%) and Mentha-2,8-diene-1-ol, cis-para (8.10%) were the most abundant. C. citratus essential oil contained 15 compounds and the major ones were geranial/citral A (48.18%) and neral/citral B (34.37%). Essential oil of C. citratus showed the highest ability to scavenge DPPH+ radicals (approximately 68% at 8 mg/mL) while C. giganteus exhibited the highest capability to reduce ABTS+ (0.59μmolET/g). The essential oil of C. citratus was the most effective on prostate cell lines LNCaP (IC50 = 6.36 μg/ml) and PC-3 (IC50 = 32.1 μg/ml), and on glioblastoma cell lines (SF-767 (IC50 = 45.13 μg/ml) and SF-763 (IC50 = 172.05 μg/ml). Interestingly, the activity of essential oil of C. citratus was statistically equal to that of its major component, citral. Combination of both oils showed antagonist, additive, indifferent and synergistic effects on LNCaP, PC-3, SF-767 and SF-763 cell lines, respectively. In conclusion, plants from the traditional medicine in Burkina Faso could be of interest for identifying new compounds, such as citral, for the treatment of prostate cancer and glioblastoma.

In vitro analysis of colistin-carbapenem combination activity against Acinetobacter spp infection.

Increasing carbapenem resistance in Acinetobacter spp calls for the appraisal of alternative strategies in Acinetobacter spp infection therapy. This study aims at evaluating colistin-carbapenem combination against Acinetobacter spp using the checkerboard, Etest, and time-kill methods. One hundred nonrepetitive Acinetobacter spp isolates were collected from patients admitted at the Saint-George-Hospital-University-Medical-Center over a one year period. The identification was performed using the API20NE and confirmed by the amplification of the blaOXA-51-like. Susceptibility to colistin, and carbapenems were determined using the Etest, microdilution methods and interpreted according to the CLSI, 2015. Detection of the carbapenemases was performed by PCR amplification method. Clonality was determined by the 3-Locus PCR-typing and ERIC-PCR methods. The synergistic potential of the combination was determined by calculating the Fractional-Inhibitory-Concentration-Index, which determines a synergistic, additive, indifferent or antagonistic effect. In our study (84%) of the isolates were carbapenem resistant. Only one strain showed resistance to colistin. (99%) and (77%) of the Acinetobacter spp isolates harbored blaOXA-51-like and blaOXA-23-like respectively. (86.2%) of the A.baumannii isolates pertained to the International Clone II. An additive effect of the colistin-carbapenem combination was determined using the 3 methods. A decrease of 2.6 and 2.8 folds in the MIC of colistin was showed in colistin-meropenem and colistin-imipenem, respectively (p < 0.001). The Colistin-meropenem showed better effects when compared to colistin-imipenem (p < 0.05). Only a few isolates showed a synergistic effect in the time-kill assay. Our study showed that the decrease in the MIC of colistin following colistin-carbapenem combination might be a promising antimicrobial approach for treating carbapenem-resistant Acinetobacter spp.