RESUMEN
To resurrect antibacterial efficacy of colistin (CLT), ceftazidime (CAZ) and cefotaxime (CTX), Stephania suberosa extract (SSE) was combined with these particular antibiotics to combat CLT-resistant Enterobacter cloacae (CREC) isolates. Disc diffusion assay showed that SSE inhibited E. cloacae strains with the dose-dependent manner. Minimum inhibitory concentrations (MICs) of SSE against all tested strains were 2000 µg ml-1 . CREC DMST 37480 and 19719 were found to be resistant to CLT with MICs of 64 and 4 µg ml-1 , respectively, and also resistant to CAZ. These strains showed a minimum bactericidal concentration (MBC) of SSE at 8000 µg ml-1 . Checkerboard assay showed that CLT resistance was synergistically reversed by SSE against CREC DMST 37480 and 19719 with a fractional inhibitory concentration (FIC) indices of 0·253 and 0·265, respectively. Time-killing assay confirmed synergistic interaction by a decline in the viability combined treated group compared to an individual. CREC DMST 19719 was found to produce AmpC ß-lactamase. SSE cannot resurrect CAZ in an AmpC producer. The scanning electron microscopy showed that SSE and CLT induced cell damages at different sites. GC-MS analysis identified 25 known Phyto-compounds. SSE and CLT combination could be further developed as a novel agent for treating multidrug-resistant CREC. SIGNIFICANCE AND IMPACT OF THE STUDY: Resistance to colistin (CLT), an alternative agent for treating multiple drug-resistant Enterobacter cloacae, is among the most serious, life-threatening issues. This study utilizes Stephania suberosa extract (SSE) to revive the antibacterial activity of colistin that has lost its antibacterial effectiveness in inhibiting E. cloacae. The findings support the development of the combined agent between SSE and colistin to conquer colistin-resistant E. cloacae.
Asunto(s)
Antibacterianos/farmacología , Proteínas Bacterianas/metabolismo , Cefotaxima/farmacología , Ceftazidima/farmacología , Colistina/farmacología , Enterobacter cloacae/efectos de los fármacos , Stephania/química , beta-Lactamasas/metabolismo , Relación Dosis-Respuesta a Droga , Sinergismo Farmacológico , Quimioterapia Combinada , Enterobacter cloacae/enzimología , Humanos , Pruebas de Sensibilidad MicrobianaRESUMEN
The continuing threat of antimicrobial resistance presents a considerable challenge to researchers to develop novel strategies ensuring that bacterial infections remain treatable. Many plant extracts have been shown to have antibacterial properties and could potentially be combined with other antibacterial agents to create more effective formulations. In this study, the antibacterial activity of three plant extracts and virulent bacteriophages have been assessed as individual components and in combination. When assessed with a modified suspension test, these plant extracts also exhibit antiviral activity at bacterial inhibitory concentrations. Hence, to investigate any potential additive effects between the extracts and virulent phages, the extracts were tested at subantiviral concentrations. Phages alone and in combination with plant extracts significantly reduced (P < 0·05) the bacterial concentration compared to untreated and extract treated controls up to 6 h (2-3log10 ), but this reduction did not extend to 24 h. In most cases, the phage and extract combinations did not significantly reduce bacterial content compared to phages alone. Additionally, there was little impact on the ability of the phages to reproduce within their bacterial hosts. To our knowledge, this study represents the first of its kind, in which antimicrobial plant extracts have been combined with virulent phages and has highlighted the necessity for plant extracts to be functionally characterized prior to the design of combinatorial therapies. Significance and Impact of Study This preliminary study provides insights into the potential combination of bacteriophages and antimicrobial plant bulk extracts to target bacterial pathogens. It is to our knowledge the first time in which virulent bacteriophages have been combined with antimicrobial plant extracts.
Asunto(s)
Antibacterianos/farmacología , Agentes de Control Biológico/farmacología , Infecciones por Escherichia coli/tratamiento farmacológico , Escherichia coli/efectos de los fármacos , Myoviridae/crecimiento & desarrollo , Extractos Vegetales/farmacología , Siphoviridae/crecimiento & desarrollo , Bignoniaceae/química , Farmacorresistencia Bacteriana Múltiple , Escherichia coli/virología , Medicina Tradicional de Asia Oriental , Pruebas de Sensibilidad Microbiana , Prueba de Estudio Conceptual , Stephania/química , Zingiberaceae/químicaRESUMEN
To address the resistance of Acinetobacter baumannii to ß-lactam antibiotics, combination therapy between different antibiotic classes is increasingly used. The antibacterial activity of α-mangostin (AMT) alone or in combination with ceftazidime (CTZ) was investigated against ceftazidime-resistant A. baumannii DMST 45378 (CRAB). Initial screening showed that A. baumannii strains possessed AmpC ß-lactamase (AmpC), extended-spectrum beta-lactamase (ESBL) and metallo-ß-lactamases (MBL). Minimum inhibitory concentrations (MICs) of all test agents were >800 µg ml-1 against CRAB. The combination of AMT/CTZ exhibited a fractional inhibitory concentration index (FICI) of <0·35 suggestive of synergy. Time-kill curves showed that the AMT/CTZ combination was significantly more efficient (P < 0·01) at reducing CRAB than the individual components. Structural analysis revealed that AMT/CTZ-treated cells exhibited increased cell volume, increased cytoplasmic and outer membrane permeability and a decrease in outer membrane peptidoglycan-associated protein (OMPG) bands. In addition, it was shown that Type IV ß-lactamase was inhibited by AMT. The data suggest that AMT in combination with CTZ is synergistic and efficient against CRAB. The data also indicate that the AMT/CTZ combination may target multiple structures on the bacterial cell surface. This represents the first report of this effect on CRAB and could potentially be expanded into in vivo studies. SIGNIFICANCE AND IMPACT OF THE STUDY: Significance and Impact of the Study: Acinetobacter baumannii strains cause serious infections, patient mortality, and have been reported to rise of multidrug resistance. This article represents the first report of using α-mangostin plus ceftazidime against these resistant strains and its mechanism of action. α-mangostin has no cytotoxic effects. Therefore, α-mangostin has strong potential for development as a useful, novel adjunct phytopharmaceutical to ceftazidime synergistically for the treatment of these strains. The synergy approach could potentially be a novel tool to combat the resistant strains.
Asunto(s)
Infecciones por Acinetobacter/tratamiento farmacológico , Acinetobacter baumannii/efectos de los fármacos , Antibacterianos/farmacología , Ceftazidima/farmacología , Inhibidores de Proteínas Quinasas/farmacología , Xantonas/farmacología , Infecciones por Acinetobacter/microbiología , Proteínas Bacterianas/metabolismo , Sinergismo Farmacológico , Quimioterapia Combinada , Humanos , Pruebas de Sensibilidad Microbiana , beta-Lactamasas/metabolismoRESUMEN
AIM: To validate a combined disc method along with resazurin chromogenic agar for early screening and differentiation of Klebsiella pneumoniae carbapenemase, metallo-ß-lactamase and OXA-48 carbapenemase-producing Enterobacteriaceae. METHODS AND RESULTS: The combined disc test comprising of meropenem alone and with EDTA, phenylboronic acid or both EDTA and phenylboronic acid, and temocillin alone were evaluated with the resazurin chromogenic agar plate assay against a total of 86 molecularly confirmed Enterobacteriaceae clinical isolates (11 metallo-ß-lactamases, eight Kl. pneumoniae carbapenemases, 11 OXA-48, 32 AmpC and 15 extended-spectrum-ß-lactamase producers and nine co-producers of extended-spectrum-ß-lactamase and AmpC). The inhibition zone diameters were measured and interpreted at 7 h for the presence of carbapenemase. All carbapenemase producers were phenotypically distinguished by this assay with 100% sensitivity and specificity. CONCLUSIONS: This early phenotypic method is very simple, inexpensive, and reliable in the detection and differentiation of carbapenemase-producing Enterobacteriaceae. It could be exploited in any microbiological laboratory for diagnosis of these recalcitrant bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: This assay poses excellent performance in discrimination of Kl. pneumoniae carbapenemase, metallo-ß-lactamase and OXA-48 carbapenemases within 7 h, which is much faster than conventional disc diffusion methods. The rapid detection could help clinicians screen patients, control infection and provide epidemiological surveillance.
Asunto(s)
Proteínas Bacterianas/análisis , Enterobacteriaceae/efectos de los fármacos , Pruebas de Sensibilidad Microbiana/métodos , Resistencia betalactámica , beta-Lactamasas/análisis , Agar , Antibacterianos/farmacología , Enterobacteriaceae/clasificación , Enterobacteriaceae/enzimología , Enterobacteriaceae/aislamiento & purificación , Infecciones por Enterobacteriaceae/microbiología , Humanos , Oxazinas , Oxitocina/análogos & derivados , XantenosRESUMEN
The purpose of this research was to investigate whether luteolin has antibacterial and synergistic activity against amoxicillin-resistant Escherichia coli (AREC) when use singly and in combination with amoxicillin. The primarily mode of action is also investigated. The susceptibility assay (minimum inhibitory concentration and checkerboard determination) was carried out by the broth macrodilution method's in Müeller-Hinton medium. MIC and checkerboard determination were carried out after 20 h of incubation at 35°C by observing turbidity. The MICs of amoxicillin and luteolin against all AREC strains were >1000 and ≥ 200 µg/ml respectively. Synergistic activity were observed on amoxicillin plus luteolin against these strains. Viable count of this combination showed synergistic effect by reducing AREC cell numbers. The results indicated that this combination altered both outer and inner membrane permeabilisation. Enzyme assay showed that luteolin had an inhibitory activity against penicillinase. Fourier Transform-Infrared (FT-IR) spectroscopy exhibited that luteolin alone and when combined with amoxicillin caused increase in fatty acid and nucleic acid, but decrease in amide I of proteins in bacterial envelops compared with control. These results indicated that luteolin has the potential to reverse bacterial resistance to amoxicillin in AREC and may operate via three mechanisms: inhibition of proteins and peptidoglycan synthesis, inhibition of the activity of certain extended-spectrum ß-lactamases and alteration of outer and inner membrane permeability. These findings offer the potential to develop a new generation of phytopharmaceuticals to treat AREC.
Asunto(s)
Amoxicilina/farmacología , Antibacterianos/farmacología , Farmacorresistencia Bacteriana/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Luteolina/farmacología , Permeabilidad de la Membrana Celular/efectos de los fármacos , Sinergismo Farmacológico , Escherichia coli/citología , Escherichia coli/enzimología , Pruebas de Sensibilidad Microbiana , Inhibidores de beta-LactamasasRESUMEN
AIM: The smaller galangal is extracted, purified and identified the bioactive compounds. The purpose of this research was to investigate whether these isolated compounds have antibacterial and synergistic activity against amoxicillin-resistant Escherichia coli (AREC) when used singly and in combination with amoxicillin. The primarily mode of action is also studied. METHOD AND RESULTS: The galangin, kaempferide and kaempferide-3-O-ß-d-glucoside were isolated. The minimum inhibitory concentrations(MIC) of amoxicillin and these flavonoids against AREC were between 500 and >1000 µg ml(-1). Synergistic activity was observed on combining amoxicillin with these flavonoids. The combinations of amoxicillin and these flavonoids exhibited a synergistic effect, reducing AREC cell numbers. Electron microscopy showed that these combinations damaged the ultrastructure of AREC cells. The results indicated that these combinations altered outer membrane permeability but not affecting cytoplasmic membrane. Enzyme assays showed that these flavonoids had an inhibitory activity against penicillinase. CONCLUSION: These results indicated that these flavonoids have the potential to reverse bacterial resistance to amoxicillin in AREC and may operate via three mechanisms: inhibition of peptidoglycan and ribosome synthesis, alteration of outer membrane permeability, and interaction with ß-lactamases. SIGNIFICANCE AND IMPACT OF THE STUDY: These findings offer the potential to develop a new generation of phytopharmaceuticals to treat AREC.
Asunto(s)
Alpinia/química , Amoxicilina/farmacología , Antibacterianos/farmacología , Farmacorresistencia Bacteriana/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Flavonoides/farmacología , Membrana Celular/efectos de los fármacos , Permeabilidad de la Membrana Celular/efectos de los fármacos , Sinergismo Farmacológico , Activación Enzimática/efectos de los fármacos , Escherichia coli/enzimología , Escherichia coli/ultraestructura , Flavonoides/química , Flavonoides/aislamiento & purificación , Quempferoles/química , Quempferoles/farmacología , Pruebas de Sensibilidad Microbiana , Rizoma/química , beta-Galactosidasa/metabolismoRESUMEN
The test organism was Escherichia coli 1810 which was highly resistant to trimethoprim (TMP). Electron microscopy (EM) of cells grown in the presence of subinhibitory concentrations of 300 micrograms/ml sulphadiazine (SD) and/or 300 micrograms/ml TMP indicated marked structural damage. No effect on the outer membrane (OM) or ultrastructure of E. coli 1810 was observed with 7.68 micrograms/ml TMP and/or 16.9 micrograms/ml SD. Concentrations of antibacterials affecting the ultrastructure of the bacterial cells of resistant and sensitive E. coli as determined by EM, were shown by a permeability probe (Triton X-100) to alter the OM permeability and to partially inhibit growth of E. coli 1810 cultures. It was concluded that, since the action of SD and TMP, singly and in combination, on the cell structure of E. coli 1810 took place only at concentrations approaching the respective MICs, then this was a part of their normal mechanisms of antibacterial action.