Inhibitory Activity of Ceiba' Honey against Escherichia Coli ATCC 33218

Escherichia coli is a type of bacteria that has evolved yearly, such as resistance to various antibiotics. Honey consumption can improve the quality of individual health. It has the potential to inhibit the growth of Escherichia coli. This study aimed to characterize the Escherichia coli ATCC 33218, and to investigate the inhibitory activity of Ceiba' honey against this strain. We obtained Ceiba' honey from the honey farm of Ceiba petandra. The antibiotic sensitivity tests revealed that the strain used in this study is not ESBL strain. Even it is resistant to Ampicillin, Amoxycillin, Penicillin, and Oxacillin and is sensitive to Cefotaxime. This study runs inhibition zone, MIC, MBC, and time-kill growth experiments to evaluate the inhibitory activity of Ceiba' honey. It showed a strong inhibition zone. Its MIC and MBC were 30 and 40%, respectively. The time-kill growth experiments revealed its inhibition by lowering the lag phase, slowing the growth rate, and decreasing the biomass yield of strain. In conclusion, Escherrichia coli ATCC 33218 is not an ESBL strain. Furthermore, Ceiba' honey has inhibitory and killing power against Escherichia coli ATCC 33218.

Preliminary phytochemical analysis, antibacterial and anti-biofilm activities of Curcuma zedoaria (Christm.) Roscoe extracts

Aims@#Plant extracts are a rich source of natural compounds that have some degree of antimicrobial efficacy and have less side effects compared to antibiotics. The aim of this research was to screen the phytochemical compounds and investigate the potency of Curcuma zedoaria (Christm.) Roscoe rhizome (CZR) extracts to inhibit the growth and biofilm formation of some pathogenic bacteria.@*Methodology and results@#Antimicrobial and antibiofilm effects of CZR extracts in different solvents were examined by agar well diffusion and the broth microdilution method after phytochemical screening. The 95% ethanolic extract of CZR exhibited broad-spectrum antibacterial properties against Gram-negative and Gram-positive bacteria with inhibition zones of 7.25 ± 0.58-12.00 ± 0.26 mm and MIC values ranging from 50-200 mg/mL. The extract also showed rapid bacteriostatic and bactericidal activities towards Enterococcus faecalis DMST 4736 and Staphylococcus aureus ATCC 25923 by time-kill assays. Moreover, the 95% ethanolic extracts of CZR also acted as a potent anti-biofilm agent against E. faecalis DMST 4736, S. aureus ATCC 25923, S. epidermidis, Escherichia coli ATCC 25922, Klebsiella pneumoniae, Pseudomonas aeruginosa ATCC 27853 and Proteus mirabilis DMST 8212 (54.62 ± 0.30-71.25 ± 0.20% inhibition of biofilm formation). The bioactive potency of compounds of the crude 95% ethanolic extract (tannins, flavonoids, cardiac glycosides, steroids, terpenoids and alkaloids) play important roles in the observed antibacterial and anti-biofilm activities.@*Conclusion, significance and impact of study@#Curcuma zedoaria (Christm.) Roscoe extract had broad-spectrum antibacterial activity. The ethanolic CZR extract revealed bacteriostatic and bactericidal capacities, depending on time of exposure and concentration of the extracts. Thus, the present results indicate that C. zedoaria (Christm.) Roscoe rhizomes are a potential natural alternative antibacterial agent for preventing bacterial diseases.

Anti-Staphylococcus aureus Methicillin-Resistant (MRSA) activity of a novel 3-Chalcogenyl Indole / Atividade Anti-Staphylococcus aureus Meticilina Resistente (MRSA) de um novo composto 3-Calcogenil Indol

Objective: the development of new drugs against Methicillin-resistant Staphylococcus aureus is a priority to the World Health Organization. So, the objective of this study was to evaluate the antibacterial activity and toxicity of 5-bromo-3-((4-methoxyphenyl) sulfenyl)-1H-indole (3b) against MRSA. Methods: minimum inhibitory concentration (MIC) of 3b was determined against S. aureus ATCC 29213 and 43 clinical isolates. The time-kill assay was performed for 9 isolates. Analysis of variance followed by the post hoc Bonferroni test was used for the statistical tests. Results and conclusions: the MIC50 and MIC90 of 3b were 4 µg.mL-1 and 16 µg.mL-1 respectively. In time-kill assay, the 3b showed bactericidal activity to all evaluated isolates at concentrations of 1xMIC and 2xMIC and the re-growth effect was not observed. About the toxicity tests, 3b has not presented cytotoxicity, mutagenicity, or allergenicity. 3b had particularly good activity against MRSA demonstrating high potential for the development of new antimicrobials products.

Objetivo: o desenvolvimento de novos antimicrobianos contra Staphylococcus aureus resistentes à meticilina (MRSA) é uma prioridade para a Organização Mundial da Saúde. Então, o objetivo desse estudo foi avaliar a atividade antibacteriana e a toxicidade do 5-bromo-3-((4-metoxifenil) sulfenil)-1H-indol (3b) contra MRSA. Métodos: a concentração inibitória minima de 3b foi determinada contra S. aureus ATCC 29213 e 43 isolados clínicos. O ensaio de curva de morte foi realizado para nove isolados. Análise de variância seguida pelo teste post hoc Bonferroni foi usada para testes estatísticos. Resultados e conclusões: a MIC50 e MIC90 do 3b foi 4 µg.mL-1 e 16 µg.mL-1, respectivamente. No ensaio de curva de morte, o 3b demonstrou atividade bactericida contra todos os isolados avaliados na concentração de 1xMIC e 2xMIC e o recrescimento não foi observado. Em relação aos testes de toxicidade, 3b não apresentou citotoxicidade, mutagenicidade ou alergenicidade. 3b apresentou atividade particularmente interessante contra MRSA, demonstrando alto potencial para o desenvolvimento de novos produtos antimicrobianos.

Antibacterial activity and mechanism of action of trigonostemone against Staphylococcus aureus and Bacillus cereus

@#In our present study, the hexane fraction from the root of the Thai medicinal plant Strophioblachia fimbricalyx Boerl. was purified and the purification led to the isolation of 3-acetylaleuritolic acid, trigonostemone and 3,6,9-trimethoxyphenanthropolone. The aims of this work are to evaluate antibacterial activity of these three isolated compounds from our local plant and to study their mechanism of actions toward target pathogenic bacteria (Gram positive and Gram negative bacteria). The antibacterial activity of isolated compounds was primary screened by agar well diffusion method and the active compound was subjected to determine for MIC and MBC values by microdilution method. The kinetic study of the bacteriostatic or bactericidal activity time-kill experiment (24 h) and mechanism of action on cell morphology toward target bacteria detected by scanning electron microscope of the active compound were further evaluated. Results indicate that among the tested three compounds, trigonostemone was the only active one. It exhibited an inhibitory effect on the growth of Gram positive bacteria, methicillin-susceptible Staphylococcus aureus (MSSA) DMST 2933, methicillin-resistant S. aureus (MRSA) DMST 20651 and Bacillus cereus ATCC 11778 with the MIC/MBC values of 12.5/25.0, 6.25/6.25 and 6.25/6.25 mg/mL, respectively. Trigonostemone possessed time- and concentration-dependent bacteriostatic activity against S. aureus (MSSA) DMST 2933 and bactericidal activity against B. cereus ATCC 11778. It caused bacteriostatic activity against S. aureus (MSSA) DMST 2933 at the concentration of 2 × MIC by changing cell morphology and bactericidal activity against B. cereus ATCC 11778 at the concentration of 2 × MIC after 4 h by inducing cell size variations at the concentrations of 2 × MIC, respectively. This finding suggests that trigonostemone isolated from the root of S. fimbricalyx has a potential to be used as natural antibacterial compound against S. aureus (MSSA) DMST 2933 and B. cereus ATCC 11778 bacterial strains.

Evaluation of Synergistic Effect of Combined Treatment with Linalool and Colistin on Multidrug-Resistant Acinetobacter baumannii to Expand Candidate for Therapeutic Option / 대한임상미생물학회지

BACKGROUND: Acinetobacter baumannii infection is a significant health problem worldwide due to increased drug resistance. The limited antimicrobial alternatives for the treatment of severe infections by multidrug-resistant A. baumannii (MDRAB) make the search for other therapeutic options more urgent. Linalool, the major oil compound in Coriandrum sativum, was recently found to have high antibacterial activity against A. baumannii. The purpose of this study was to investigate the synergistic effect of linalool and colistin combinations against MDRAB and extensively drug-resistant A. baumannii (XDRAB).METHODS: A total of 51 strains of A. baumannii clinical isolates, consisting of 10 MDRAB and 41 XDRAB were tested. We determined the minimum inhibitory concentration (MIC) of linalool for the test strains using the broth microdilution method and searched for interactions using the time-kill assay.RESULTS: The time-kill assay showed that the linalool and colistin combination displayed a high rate of synergy (92.1%) (by synergy criteria 2), low rate of indifference (7.8%), and a high rate of bactericidal activity (74.5%) in the 51 clinical isolates of A. baumannii. The synergy rates for the linalool and colistin combination against MDRAB and XDRAB were 96% and 92.1%, respectively. No antagonism was observed for the linalool and colistin combination.CONCLUSION: The combination of linalool and colistin showed a high synergy rate, which may be beneficial for controlling MDRAB infections. Therefore, this combination is a good candidate for in vivo studies to assess its efficacy in the treatment of MDRAB infections.

Time-kill study and morphological changes of Proteus mirabilis cells exposed to ethyl acetate crude extract of Lasiodiplodia pseudotheobromae IBRL OS-64

@#Aims: To investigate time-kill curve and morphological changes of Proteus mirabilis cells exposed to ethyl acetate crude extract of endophytic fungus, Lasiodiplodia pseudotheobromae IBRL OS-64, isolated from Ocimum sanctum. Methodology and results: Inhibitory effect of the fungal extract against the test bacteria via disc diffusion assay showed a fair antibacterial activity with diameter of inhibition zone was 12.0 ± 0.4 mm. The Minimal Inhibition Concentration (MIC) and Minimal Bactericidal Concentration (MBC) values of the ethyl acetate extract against P. mirabilis was 250 and 500 µg/mL, respectively. The value of MBC which is two-fold higher than MIC value indicated that the fungal extract exerted bactericidal effect on bacterial cells of P. mirabilis. Time-kill curve study revealed that the bactericidal effect of the crude extract towards test bacteria was both dose and time dependent. Scanning electron microscope (SEM) observation revealed that the bacterial cells of P. mirabilis exposed to fungal crude extract resulted in formation of pits, irregular shape of the bacterial cell and ultimately cell death beyond repair. Conclusion, significance and impact of the study: The time-kill curve study, and cell morphological changes suggested the potential of ethyl acetate extract of L. pseudotheobromae IBRL OS-64 against P. mirabilis infection by formation of cavities, irregular bacterial cell that leads to ultimate cell death and the extract may have pharmaceutical potential to be develop as antibacterial agent.

Time-kill assay and post-antibiotic effect of acetone extract from the stem bark of Canarium odontophyllum against Methicillin-resistant Staphylococcus aureus Mu50 strain

Canarium odontophyllum Miq. is an indigenous fruit found in Sarawak, Malaysia. Methicillin-resistant Staphylococcusaureus (MRSA) is a deadly pathogen that causes to hospital (health-care-acquired MRSA [HA-MRSA]) and community(CA-MRSA) infections worldwide. Vancomycin has been the therapeutic drug of choice against MRSA, but unfortunatelythis pathogen has developed some degree of resistance to vancomycin. This research aimed to evaluate the antimicrobialactivity of the stem bark extract of C. odontophyllum against MRSA Mu50 strain. The minimum inhibitory concentration(MIC) and minimum bactericidal concentration (MBC) of extract and vancomycin against MRSA were determined usingbroth microdilution method and streak plate method. The rate of killing by the extract against Mu50 strain was determinedusing time-kill assay (TKA) at ×1 MIC, ×2 MIC, ×4 MIC, and ×8 MIC of the extract. The post-antibiotic effect (PAE) timeof extract ×10 MIC against MRSA was also investigated. The extract exhibited bacteriostatic effect against MRSA Mu50strain with MIC and MBC values of 1.563 mg/ml and 3.125 mg/ml, respectively. From TKA analysis, the extract was notcapable of killing the Mu50 strain at ×1 MIC and ×2 MIC, but it displayed bactericidal activity at higher concentrationstested. Interestingly, the acetone stem bark extract of C. odontophyllum at ×4 MIC showed comparable time-killingkinetic with the standard antibiotic in the study. The PAE time of the extract was 3.6 ± 0.51 h against MRSA Mu50compared to vancomycin at 2.4 ± 0.68 h. In conclusion, the stem bark acetone extract from C. odontophyllum demonstratedconcentration-dependent bactericidal effect with prolonged PAE time against MRSA Mu50 strain.

Evaluation of synergism between Cefotaxime and Allium sativum against Extended-spectrum beta-lactamase and Ambler class C co-producers

The present study evaluates the synergistic association between Cefotaxime and aqueous garlic (Allium sativum)extract (AGE) on extended spectrum beta-lactamase (ESBL) and Ambler Class C (AmpC) co-producing Escherichiacoli strains from skin and soft tissue infections (SSTIs). Ceftazidime-resistant E. coli strains were screened for betalactamase production by phenotypic confirmatory disc diffusion test (PCDDT) and E-test. Antibacterial activity ofAGE was examined by the disc diffusion method and the minimum inhibitory concentration (MIC) of Cefotaximeand AGE was determined. The synergistic association between Cefotaxime and AGE was evaluated by calculatingthe fractional inhibitory concentration (FIC) index, time-kill kinetics assay (TKA), and scanning electron microscopy(SEM). The zone of inhibition by AGE against the 27 E. coli co-producers of ESBL and AmpC ranged from 17 to 30mm. The average MIC of Cefotaxime and AGE was found to be 570 μg/ml and 0.86% (4.28 mg/ml), respectively. TheFIC index obtained by the checkerboard method established a synergistic association between Cefotaxime and AGEin 10 (37%) test strains, which was confirmed by TKA. The SEM analysis revealed complete cell degradation at 8hours on the treatment with Cefotaxime-AGE combination. It can be stated that the AGE may aid Cefotaxime in thetreatment of beta-lactamase producing E. coli strains from SSTIs.

Evaluation of synergism between Cefotaxime and Allium sativum against Extended-spectrum beta-lactamase and Ambler class C co-producers

The present study evaluates the synergistic association between Cefotaxime and aqueous garlic (Allium sativum)extract (AGE) on extended spectrum beta-lactamase (ESBL) and Ambler Class C (AmpC) co-producing Escherichiacoli strains from skin and soft tissue infections (SSTIs). Ceftazidime-resistant E. coli strains were screened for betalactamase production by phenotypic confirmatory disc diffusion test (PCDDT) and E-test. Antibacterial activity ofAGE was examined by the disc diffusion method and the minimum inhibitory concentration (MIC) of Cefotaximeand AGE was determined. The synergistic association between Cefotaxime and AGE was evaluated by calculatingthe fractional inhibitory concentration (FIC) index, time-kill kinetics assay (TKA), and scanning electron microscopy(SEM). The zone of inhibition by AGE against the 27 E. coli co-producers of ESBL and AmpC ranged from 17 to 30mm. The average MIC of Cefotaxime and AGE was found to be 570 μg/ml and 0.86% (4.28 mg/ml), respectively. TheFIC index obtained by the checkerboard method established a synergistic association between Cefotaxime and AGEin 10 (37%) test strains, which was confirmed by TKA. The SEM analysis revealed complete cell degradation at 8hours on the treatment with Cefotaxime-AGE combination. It can be stated that the AGE may aid Cefotaxime in thetreatment of beta-lactamase producing E. coli strains from SSTIs

In vitro assessment of the synergism between extracts of Cocos nucifera husk and some standard antibiotics

Objective To evaluate the interactions between the crude extracts of Cocos nucifera (C. nucifera) and six front line antibiotics (ampicillin sodium salt, penicillin G sodium, amoxicillin, chloramphenicol, ciprofloxacin and tetracycline hydrochloride), against some bacterial pathogens linked with human infection. Methods The pulverized husk of C. nucifera was dissolved in 95% n-hexane and extracted using Soxhlet extraction method and sterile distilled water (aqueous). The antibacterial susceptibility of the crude extracts of C. nucifera was tested against environmental and clinical strains (6) obtained from the South African Bureau of Standards (SABS), Vibrio (6) and Listeria pathogens (6). The agar-well diffusion method was used for screening the extracts for their antibacterial activity. The minimum inhibitory concentration and minimum bactericidal concentration of the extracts were determined. Time-kill assay was used to evaluate bactericidal and/or bacteriostatic activity. The synergistic effect of the crude extracts and antibiotics was assessed and evaluated by adopting the checkerboard methods. Results With the time-kill assay, the highest bactericidal activity was observed on Vibrio fluvialis EL041 with a −5.6 ± 0.2 log

Morphological alterations and time-kill studies of the essential oil from the leaves of Coriandrum sativum L. on Candida albicans / Alteraciones morfológicas y estudios de letalidad del aceite esencial de las hojas de Coriandrum sativum L. en Candida albicans

The objective of this study was to evaluate the morphological alterations and time-kill of the essential oil of the leaves of C. sativum L. on strains of C. albicans. The essential oil was submitted to gas chromatography-mass spectrometry analysis. The predominant component identified was linalool (39.78 percent). Minimal inhibitory concentration and minimal fungicidal concentration of the essential oil were respectively 512 and 1024 ug.mL-1 for 90 percent of the strains tested. In the time-kill curves, the essential oil showed a concentration-dependent fungicidal effect. In the micromorphology assay it caused a significant reduction in pseudohyphae, an important pathogenic factor of C. albicans.

El objetivo de este estudio fue evaluar las alteraciones morfológicas y de letalidad del aceite esencial de las hojas de C. sativum L. en cepas de C. albicans. El aceite esencial se presentó a gas análisis de espectrometría de cromatografía-masa. El componente predominante identificado fue linalol (39,78 por ciento). Concentración inhibitoria mínima y concentración mínima fungicida del aceite esencial fueron, respectivamente, 512 y 1.024 ìg.mL-1 para 90 por ciento de las cepas probadas. En las curvas el tiempo-matar, el aceite esencial mostró un efecto fungicida dependiente de la concentración. En el ensayo de micromorfología causó una reducción significativa en pseudohifas, un importante factor patógeno de C. albicans.

Synergistic antibacterial action of β-sitosterol-D-glucopyranoside isolated from Desmostachya bipinnata leaves with antibiotics against common human pathogens

Desmostachya bipinnata (L.) Stapf, Poaceae, or Kusha in Sanskrit, is a sacred grass used extensively in Indian Vedic practices. It is well known for its medicinal value and is used in traditional Indian medicine to treat microbial infection in combination with other herbs. An effort has been made to isolate and characterize the bioactive compounds from the hydroalcoholic extract of D. bipinnata through bioassay guided fractionation, column chromatography. Their individual or combined antimicrobial properties were determined by the Resazurin Microtitre Assay, the checkerboard assay in combination with antibiotics, and by time kill curve analysis. β-Sitosterol-D-glucopyranoside was the bioactive compound identified to have the best antimicrobial activity (MIC 6-50 µg/ml) and it works synergistically with most antibiotics, especially with ciprofloxacin. Time kill curves showed that BS kills most of the pathogens within 5-10 h. To our knowledge at its best, this is the first time report of antibacterial synergy of β-sitosterol-D-glucopyranoside from D. bipinnata.

Combined antimicrobial susceptibility test against pan-drug-resistant Acinetobacter baumannii with E-test and microdilution checkerboard assay / 中华微生物学和免疫学杂志

Objective To evaluate the activity of antibiotics against pan-drug-resistant (PDR) Acinetobacter baumannii by combination antimicrobial susceptibility test in viro with epsilometric methods (Etest method) and microdilution checkerboard (CB method),and to detect a good correlation between timekill curve with the above mentioned two assays.Methods Thirty-one clinical isolates of PDR Acinetobacter baumannii were selected for mono and combination antimicrobial susceptibility test in vitro by E-test and CB method,then a comparison was conducted between the test results and the time-kill curve.Mono drugs involved tigecycline,colistin,imipenem and amikacin,and combinations involved two of drugs above,and three drugs involved imipenem/tigecycline,plus amikacin combination.Results Synergistic effect was detected in imipenem plus colistin and tigecycline plus imipenem combination.A high comparability was revealed between the E-test method with antimicrobial drugs added into the culture medium and the time-kill curves.Synergy in the combination of imipenem/tigecycline,plus amikacin was detected by the CB method and time-kill curves.Conclusion The results showed that the effect of specific combination of antibiotics against PDR Acinetobacter baumannii could be predicted by testing their synergistic effect with combination antimicrobial susceptibility test.

Atividade antimicrobiana in vitro de produtos antissépticos por meio de técnica time kill / Analysis of in vitro antimicrobial activity of antiseptics products by means of time kill assay

Inúmeros agentes químicos (álcoois, iodóforos, clorexidina, etc.) são utilizados em laboratórios e indústrias.Ao contrário dos desinfetantes, não há padrões e critérios específicos para avaliar a atividade de antissépticos.Neste trabalho foi estudada a atividade antimicrobiana de antissépticos, utilizando-se o ensaio Time Kill (Hobson & Bolsen), que avalia a população de micro-organismos aeróbios em período de tempo específico,diante de agentes antimicrobianos. Foram avaliadas duas metodologias de recuperação dos microorganismos: filtração por membrana e semeadura em profundidade. A filtração por membrana foi menos sensível. A semeadura em profundidade demonstrou maior sensibilidade com maior contagem de colônias.De 25 amostras de produtos, os antissépticos à base de digluconato de clorexidina foram insatisfatórios e ineficazes para todas as cepas de micro-organismos de referência, correspondendo a 20 % das amostras analisadas. Estes produtos apresentaram-se satisfatórios frente às cepas de origem clínica. Portanto, estes produtos devem ser utilizados com cautela e estudos adicionais são necessários, pois são escassas as informações sobre sua eficácia. Os dados deste estudo poderão auxiliar as ações de vigilância sanitária e de saúde pública na elaboração de futuras legislações, pois estes produtos são encontrados no comércio, massem seguir nenhuma legislação específica.

Many chemicals (alcohol, iodophor, chlorhexidine, etc) are used in laboratories and industries. Unlikedisinfectants, no specific norms and criteria have been standardized for evaluating the antiseptics activity.This study analyzed the antimicrobial activity of antiseptics using Time Kill Test (Hobson & Bolsen).This assay assessed the evolution of a population of aerobic microorganisms in a specific period oftime when tested against antimicrobial agents. Two different recovery methodologies were evaluated:membrane filtration and pour plate technique The membrane filtration assay was less sensitive. Pour platetechnique showed high sensitivity with high colonies counts. Of 25 samples of products analyzed, onlythe chlorhexidine digluconate-based antiseptics were unsatisfactory, showing no efficacy on all referencemicro-organisms strains, and corresponded to 20 % of analyzed samples. However, they were efficaciousagainst clinical strains. Therefore, these products should be used with caution and further studies areneeded, as data on its efficacy have still been scarce. These findings might give support to the healthsurveillance and public health in establishing the future legislation, as these products have been availableon the market, but without following any specific legislation.

Evaluation of the synergistic potential of vancomycin combined with other antimicrobial agents against methicillin-resistant Staphylococcus aureus and coagulase-negative Staphylococcus spp strains

Methicillin-resistant Staphylococcus aureus (MRSA) and coagulase-negative Staphylococcus spp (CNS) are the most common pathogens that cause serious long term infections in patients. Despite the existence of new antimicrobial agents, such as linezolid, vancomycin (VAN) remains the standard therapy for the treatment of infections caused by these multidrug-resistant strains. However, the use of VAN has been associated with a high frequency of therapeutic failures in some clinical scenarios, mainly with decreasing concentration of VAN. This work aims to evaluate the synergic potential of VAN plus sulfamethoxazole/trimethoprim (SXT), VAN plus rifampin (RIF) and VAN plus imipenem (IPM) in sub-minimum inhibitory concentrations against 22 clinical strains of MRSA and CNS. The checkerboard method showed synergism of VAN/RIF and VAN/SXT against two and three of the 22 strains, respectively. The combination of VAN with IPM showed synergistic effects against 21 out of 22 strains by the E-test method. Four strains were analyzed by the time-kill curve method and synergistic activity was observed with VAN/SXT, VAN/RIF and especially VAN/IPM in sub-inhibitory concentrations. It would be interesting to determine if synergy occurs in vivo. Evidence of in vivo synergy could lead to a reduction of the standard VAN dosage or treatment time.

In vitro antifungal activity and cytotoxic effect of essential oils and extracts of medicinal and aromatic plants against Candida krusei and Aspergillus fumigatus / Atividade antifúngica in vitro e os efeitos citotóxicos de óleos essenciais e extratos de plantas medicinais e aromáticas contra Candida krusei e Aspergillus fumigatus

The plants are usually used in traditional medicine as antimicrobial agents and their essential oils and extracts have been known to possess antifungal activity. The aim of this study was to evaluate in vitro the activity of 32 essential oils and 29 extracts against C. krusei and A. fumigatus as well as the cytotoxic effect on Vero cells. Time-kill curve and interaction between antifungals and the most active sample against C. krusei, was also evaluated. The oils from C. ambrosioides and the extract of M. cucullata showed antifungal activity against C. krusei (GM-MIC 7.82 and 31.25 µg/mL, respectively). L. citriodora was actives against C. krusei and A. fumigates (GM-MIC = 99.21 µg/mL and 62.5 µg/mL respectively). Time-kill assays done with C. ambrosioides oil showed fungicidal activity at 4x MIC. The interaction of C. ambrosioides oil with itraconazole and amphotericin B was tested following the chequerboard technique. No interaction was detected for the combination of C. ambrosioides oil with amphotericin B and itraconazole (FICI range = 1.03-1.06 and 1.03-1.00, respectively). Cytotoxicity assays for all samples were carried out with MTT. Only the oil from Hedyosmun sp. and L. dulcis were cytotoxic.

As plantas são geralmente utilizadas na medicina tradicional como agentes antimicrobianos e seus óleos essenciais e extratos foram conhecidos por possuir atividade antifúngica. O objetivo deste estudo foi avaliar in vitro a atividade de 32 óleos essenciais e 29 extratos contra Candida krusei e Aspergillus fumigatus, bem como o efeito citotóxico em células Vero. A curva do tempo-morte e a interação entre antifúngicos e Chenopodium ambrosioidese do extrato de Myrcia cucullata mostraram atividade antifúngica contra C. krusei (geometric means of the minimal inhibitory concentration [GM-MIC] 7,82 e 31,25 µg/mL, respectivamente). Lippia citriodora foi ativa contra C. krusei e A. fumigatus (GM-CIM = 99,21 µg/mL e 62,5 µg/mL, respectivamente). Os testes de tempo-morte feitos com óleo de C. ambrosioides mostraram atividade fungicida em 4x MIC. A interação do óleo C. ambrosioides com itraconazol e anfotericina B foi testada pela técnica de xadrez. Nenhuma interação foi detectada pela combinação do óleo C. ambrosioides com anfotericina B e itraconazol (intervalo fractional inhibitory index [FICI] = 1,03-1,06 e 1,03-1,00, respectivamente). Os ensaios de citotoxicidade para todas as amostras foram realizadas com MTT. Apenas os óleos Hedyosmun sp. e L. dulcis foram citotóxicos.

Susceptibility testing of Candida albicans isolated from oropharyngeal mucosa of HIV+ patients to fluconazole, amphotericin B and Caspofungin: Killing kinetics of caspofungin and amphotericin B against fluconazole resistant and susceptible isolates / Teste de suscetibilidade de Candida albicans isoladas da mucosa orofaringeana de pacientes HIV+, ao fluconazol, anfotericcina B e caspofungina: Cinética de morte de caspofungina e anfotericina B contra isolados fluconazol resistentes e suscetíveis

A clear understanding of the pharmacodynamic properties of antifungal agents is important for the adequate treatment of fungal infections like candidiasis. For certain antifungal agents, the determination of Minimal Fungicidal Concentration (MFC) and time kill curve could be clinically more relevant than the determination of the Minimal Inhibitory Concentration (MIC). In this study, MIC and MFC to fluconazole, amphotericin B and caspofungin against C. albicans isolates and the killing patterns obtained with caspofungin and amphotericin B against susceptible and resistant strains to fluconazole were determined. The results of MICs showed that all C. albicans isolates were highly susceptible to amphotericin B, but two isolates were fluconazole resistant. The comparative analysis between MIC and MFC showed that MFC of fluconazole was fourfold higher than MIC in 41.9% of the C. albicans isolates. Same values of MFC and MIC of amphotericin B and caspofungin were found for 71% of the isolates. Correlation between time kill curves and MFC of amphotericin B and caspofungin against all 4 isolates tested was observed. The caspofungin killing effect was more evident at MFC in 6 hours of incubation than at MIC in this time, suggesting dependence of concentration. The similarity of results of time-kill curve and MFC values indicate that determination of MFC is an alternative for the detection of the fungicidal activity of these drugs.

Um claro entendimento das propriedades farmacodinâmicas dos agentes antifúngicos é de grande importância para o adequado tratamento das infecções fúngicas como a candidíase. Em alguns casos de escolha do agente antifúngico, a determinação da concentração fungicida minima (CFM) e a curva do tempo de morte podem ser mais clinicamente relevantes do que a concentração inibitória minima (CIM). Nesse estudo, foi avaliado a CIM e a CFM de fluconazol, anfotericina B e caspofungina em Candida albicans e ainda os padrões de morte obtidos com caspofungina e anfotericina B de isolados suscetíveis e resistentes ao fluconazol. Os resultados de CIM mostraram que todos os isolados de Candida albicans foram altamente suscetíveis à anfotericina B, entretanto dois isolados foram fluconazol resistentes. A análise comparativa de CIM e da CFM mostrou que o CFM de fluconazol foi quatro vezes superior à CIM para 41,9% dos isolados de Candida albicans. Valores iguais de CFM e CIM de anfotericina B e caspofungina foram encontrados para 71% dos isolados. Correlação entre a curva do tempo de morte e a CFM de anfotericina B e caspofungina contra quatro isolados testados foi observada. O efeito de morte de caspofungina foi mais evidente na CFM até 6 horas de incubação do que na CIM nesse mesmo tempo, sugerindo a dependência da concentração. A similaridade dos resultados da curva do tempo de morte e os valores de CFM indicam que a determinação da CFM é uma escolha alternativa na detecção da atividade fungicida destes agentes antifúngicos.

Synergistic interaction of Helichrysum pedunculatum leaf extracts with antibiotics against wound infection associated bacteria

The effect of combinations of the crude methanolic extract of the leaves of Helichrysum pedunculatum and eight first-line antibiotics were investigated by time kill assays against a panel of bacterial strains that have been implicated in wound infections. The plant extract showed appreciable antibacterial activities against the test bacteria with zones of inhibition ranging between 18 and 27 mm, and minimum inhibitory concentrations (MICs) varying between 0.1 and 5.0 mg/ml. The MICs of the test antibiotics range between 0.001 and 0.412 mg/ml, and combination of the plant extract and the antibiotics resulted in reduction of bacterial counts by between 0 and 6.63 Log10 cfu/ml. At V2 MIC, 56.81 percent synergy; 43.19 percent indifference and no antagonism were observed, and at MIC levels, 55.68 percent synergy; 44.32 percent indifference and no antagonism were observed when the extracts were combined with eight different antibiotics. In all, 60 percent of the interactions were synergistic. All combination regimes on Staphylococcus aureus ATCC 6538 yielded no synergy, neither was antagonism detected in any of the assays. We propose that extracts of the leaves of Helichrysum pedunculatum could be of relevance in combination therapy and as a source of resistance modifying principies that could be useful as treatment options for persistent wound infections.

In vitro Antimicrobial Synergy against Imipenem-Resistant Acinetobacter baumannii / 대한진단검사의학회지

BACKGROUND: Most imipenem-resistant Acinetobacter baumannii (IRAB) isolates are multiresistant, leaving few options for an effective antimicrobial therapy. We purposed to select possible candidates for the combinations of antimicrobials that are synergistic in vitro for inhibitory or bactericidal activities against IRAB and evaluate the usefulness of double disk synergy test (DDS) in predicting synergistic bactericidal activity. METHODS: Fifty-five IRAB isolates recovered from patients during the period from August 1999 to November 2000 were tested for susceptibilities to amikacin, gentamicin, tobramycin, piperacillin, piperacillin/tazobactam, cefotaxime, cefepime, cefoperazone/sulbactam (C/S), imipenem, meropenem, ciprofloxacin, levofloxacin, trimethoprim/sulfamethoxazole, chloramphenicol, minocycline, and colistin by the Clinical and Laboratory Standard Institute agar dilution method. Three isolates showing different susceptibility profiles were tested for antimicrobial synergy by DDS and then by timekill study (TKS) using DDS-positive combinations. RESULTS: Colistin, C/S, and minocycline were active in 50 (90.9%), 50, and 44 (80.0%) isolates, respectively, and all the other drugs were active in less than 20% of isolates. Minocycline-imipenem, minocycline-C/S, minocycline-amikacin, imipenem-tobramycin, C/S-amikacin, and C/S-tobramycin combinations showed synergistic inhibitory or bactericidal activity by TKS when the same combinations were synergistic in DDS; however, C/S-imipenem was found synergistic on DDS, but not by TKS. CONCLUSIONS: Colistin, C/S, and minocycline were relatively active against IRAB. DDS might help predict the synergistic antimicrobial effect of TKS if one of the combinations was susceptible.

Synergy of Arbekacin-based Combinations Against Vancomycin Hetero-intermediate Staphylococcus aureus

This study was undertaken to evaluate the in vitro activities of arbekacin-based combination regimens against vancomycin hetero-intermediate Staphylococcus aureus (hetero-VISA). Combinations of arbekacin with vancomycin, rifampin, ampicillin-sulbactam, teicoplanin, or quinipristin-dalfopristin against seven hetero-VISA strains and two methicillin-resistant S. aureus strains were evaluated by the time-kill assay. The combinations of arbekacin with vancomycin, teicoplanin, or ampicillinsulbactam showed the synergistic interaction against hetero-VISA strains. Data suggest that these arbekacin-based combination regimens may be useful candidates for treatment options of hetero-VISA infections.