Synergistic antibacterial activity of Phyllanthus emblica fruits and its phytocompounds with ampicillin: a computational and experimental study.

Phyllanthus emblica L. (syn. Emblica officinalis), popularly known as amla, Indian gooseberry, or the King of Rasyana, is a member of Phyllanthaceae family and is traditionally used in Ayurveda as an immunity booster. The present study aimed to investigate the synergistic interaction of Phyllanthus emblica (FPE) fruits and its selected phytocompounds with ampicillin against selected bacteria. Further, an in silico technique was used to find if major phytocompounds of FPE could bind to proteins responsible for antibiotic resistance in bacterial pathogens and enhance the bioactivity of ampicillin. FPE and all the selected phytocompounds were found to have synergistic antibacterial activity with ampicillin against tested bacteria in different combinations. However, ellagic acid and quercetin interactions with ampicillin resulted in maximum bioactivity enhancement of 32-128 folds and 16-277 folds, respectively. In silico analysis revealed strong ellagic acid, quercetin, and rutin binding with penicillin-binding protein (PBP-) 3, further supported by MD simulations. Ellagic acid and quercetin also fulfill Lipinski's rule, showing similar toxicity characteristics to ampicillin. FPE showed synergistic interaction with ampicillin, possibly due to the presence of phytocompounds such as gallic acid, ellagic acid, quercetin, and rutin. Molecular docking and MD simulations showed the strong interaction of ellagic acid and quercetin with PBP-3 protein. Therefore, these compounds can be explored as potential non-toxic drug candidates to combat bacterial antimicrobial resistance.

Nitrogen and phosphorus eutrophication enhance biofilm-related drug resistance in Enterococcus faecalis isolated from Water Sources.

Antibiotic resistance is a critical topic worldwide with important consequences for public health. So considering the rising issue of antibiotic-resistance in bacteria, we explored the impact of nitrogen and phosphorus eutrophication on drug resistance mechanisms in Enterococcus faecalis, especially ciprofloxacin, oxytetracycline, and ampicillin. For this purpose we examined the antibiotic-resistance genes and biofilm formation of Enterococcus faecalis under different concentration of nitrogen and phosphorus along with mentioned antibiotics. Mesocosms were designed to evaluate the impact of influence of eutrophication on the underlying mechanism of drugn resistence in Enterococcus faecalis. For this purpose, we explored the potential relation to biofilm formation, adhesion ability, and the expression levels of the regulatory gene fsrA and the downstream gene gelEI. Our results demonstrated that the isolates of all treatments displayed high biofilm forming potential, and fsrA and gelE genes expression. Additionally, the experimental group demonstrated substantially elevated Enterococcus faecalis gelE expression. Crystal violet staining was applied to observe biofilm formation during bacterial development phase and found higher biofilm formation. In conclusion, our data suggest that E. faecalis resistance to ciprofloxacin, oxytetracycline, and ampicillin is related to biofilm development. Also, the high level of resistance in Enterococcus faecalis is linked to the expression of the fsrA and gelE genes. Understanding these pathways is vital in tackling the rising problem of bacterial resistance and its potential effect on human health.

Effect of hyperbaric oxygen on the growth and susceptibility of facultatively anaerobic bacteria and bacteria with oxidative metabolism to selected antibiotics.

Wild strains of Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis were tested in an experimental hyperbaric chamber to determine the possible effect of hyperbaric oxygen on the susceptibility of these strains to the antibiotics ampicillin, ampicillin + sulbactam, cefazolin, cefuroxime, cefoxitin, gentamicin, sulfamethoxazole + trimethoprim, colistin, oxolinic acid, ofloxacin, tetracycline, and aztreonam during their cultivation at 23 °C and 36.5 °C. Ninety-six-well inoculated microplates with tested antibiotics in Mueller-Hinton broth were cultured under standard incubator conditions (normobaric normoxia) for 24 h or in an experimental hyperbaric chamber (HAUX, Germany) for 24 h at 2.8 ATA of 100% oxygen (hyperbaric hyperoxia). The hyperbaric chamber was pressurised with pure oxygen (100%). Both cultures (normoxic and hyperoxic) were carried out at 23 °C and 36.5 °C to study the possible effect of the cultivation temperature. No significant differences were observed between 23 and 36.5 °C cultivation with or without the 2-h lag phase in Pseudomonas aeruginosa, Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. Cultivation in a hyperbaric chamber at 23 °C and 36.5 °C with or without a 2-h lag phase did not produce significant changes in the minimum inhibitory concentration (MIC) of Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis. For the tested strains of Pseudomonas aeruginosa, the possible effect of hyperbaric oxygen on their antibiotic sensitivity could not be detected because the growth of these bacteria was completely inhibited by 100% hyperbaric oxygen at 2.8 ATA under all hyperbaric conditions tested at 23 °C and 36.5 °C. Subsequent tests with wild strains of pseudomonads, burkholderias, and stenotrophomonads not only confirmed the fact that these bacteria stop growing under hyperbaric conditions at a pressure of 2.8 ATA of 100% oxygen but also indicated that inhibition of growth of these bacteria under hyperbaric conditions is reversible.

A metagenomic analysis for combination therapy of multiple classes of antibiotics on the prevention of the spread of antibiotic-resistant genes.

Antibiotics used systemically to treat infections may have off-target effects on the gut microbiome, potentially resulting in the emergence of drug-resistant bacteria or selection of pathogenic species. These organisms may present a risk to the host and spread to the environment with a risk of transmission in the community. To investigate the risk of emergent antibiotic resistance in the gut microbiome following systemic treatment with antibiotics, this metagenomic analysis project used next-generation sequencing, a custom-built metagenomics pipeline, and differential abundance analysis to study the effect of antibiotics (ampicillin, ciprofloxacin, and fosfomycin) in monotherapy and different combinations at high and low doses, to determine the effect on resistome and taxonomic composition in the gut of Balb/c mice. The results showed that low-dose monotherapy treatments showed little change in microbiome composition but did show an increase in expression of many antibiotic-resistant genes (ARGs) posttreatment. Dual combination treatments allowed the emergence of some conditionally pathogenic bacteria and some increase in the abundance of ARGs despite a general decrease in microbiota diversity. Triple combination treatment was the most successful in inhibiting emergence of relevant opportunistic pathogens and completely suppressed all ARGs after 72 h of treatment. The relative abundances of mobile genetic elements that can enhance transmission of antibiotic resistance either decreased or remained the same for combination therapy while increasing for low-dose monotherapy. Combination therapy prevented the emergence of ARGs and decreased bacterial diversity, while low-dose monotherapy treatment increased ARGs and did not greatly change bacterial diversity.

Synthesis and characterisation of gold nanoparticles from acacia leaf and to evaluate anticariogenic activity.

Objective: To synthesise the gold nanoparticles (AuNPs) using Acacia catechu through biogenic synthesis and evaluate their antimicrobial efficacy against S. mutans and E. coli in vitro. Methods: Green synthesised AuNPs were characterised using the ultraviolet-visible (UV-Vis) spectroscopy, and the size and shape of the synthesised nanoparticles were evaluated using the transmission electron microscopy (TEM). The antimicrobial efficacy of AuNPs (30/60/100 µl) against S. mutans/E. coli was evaluated on the Mueller-Hinton agar by measuring the zone of inhibition (ZOI) with ampicillin (15 µl) as a positive control. Results: The synthesised AuNPs were confirmed using the UV-Vis spectroscopy with peaks at 540 nm, and the size of the particle estimated using the TEM was between 5 and 15 nm. The antimicrobial efficacy of AuNPs was comparable to that of ampicillin against S. mutans/E. coli, but the difference was not significant. The antimicrobial effects increased in a dose-dependent fashion but were comparable across all concentrations and ampicillin. Conclusion: Green synthesised AuNPs exhibited significant antibacterial activity against S. mutans and E. coli at par with commercial ampicillin and demonstrated the potential towards anticariogenic agent for future use in dentistry.

Medicinal plant Miconia albicans synergizes with ampicillin and ciprofloxacin against multi-drug resistant Acinetobacter baumannii and Staphylococcus aureus.

BACKGROUND: Given the rising occurrence of antibiotic resistance due to the existence and ongoing development of resistant bacteria and phenotypes, the identification of new treatments and sources of antimicrobial agents is of utmost urgency. An important strategy for tackling bacterial resistance involves the utilization of drug combinations, and natural products derived from plants hold significant potential as a rich source of bioactive compounds that can act as effective adjuvants. This study, therefore, aimed to assess the antibacterial potential and the chemical composition of Miconia albicans, a Brazilian medicinal plant used to treat various diseases. METHODS: Ethanolic extracts from leaves and stems of M. albicans were obtained and subsequently partitioned to give the corresponding hexane, chloroform, ethyl acetate, and hydromethanolic phases. All extracts and phases had their chemical constitution investigated by HPLC-DAD-MS/MS and GC-MS and were assessed for their antibiofilm and antimicrobial efficacy against Staphylococcus aureus. Furthermore, their individual effects and synergistic potential in combination with antibiotics were examined against clinical strains of both S. aureus and Acinetobacter baumannii. In addition, 10 isolated compounds were obtained from the leaves phases and used for confirmation of the chemical profiles and for antibacterial assays. RESULTS: Based on the chemical profile analysis, 32 compounds were successfully or tentatively identified, including gallic and ellagic acid derivatives, flavonol glycosides, triterpenes and pheophorbides. Extracts and phases obtained from the medicinal plant M. albicans demonstrated synergistic effects when combined with the commercial antibiotics ampicillin and ciprofloxacin, against multi-drug resistant bacteria S. aureus and A. baumannii, restoring their antibacterial efficacy. Extracts and phases also exhibited antibiofilm property against S. aureus. Three key compounds commonly found in the samples, namely gallic acid, quercitrin, and corosolic acid, did not exhibit significant antibacterial activity when assessed individually or in combination with antibiotics against clinical bacterial strains. CONCLUSIONS: Our findings reveal that M. albicans exhibits remarkable adjuvant potential for enhancing the effectiveness of antimicrobial drugs against resistant bacteria.

DNA Nanoflower Eye Drops with Antibiotic-Resistant Gene Regulation Ability for MRSA Keratitis Target Treatment.

Methicillin-resistant Staphylococcus aureus (MRSA) biofilm-associated bacterial keratitis is highly intractable, with strong resistance to ß-lactam antibiotics. Inhibiting the MRSA resistance gene mecR1 to downregulate penicillin-binding protein PBP2a has been implicated in the sensitization of ß-lactam antibiotics to MRSA. However, oligonucleotide gene regulators struggle to penetrate dense biofilms, let alone achieve efficient gene regulation inside bacteria cells. Herein, an eye-drop system capable of penetrating biofilms and targeting bacteria for chemo-gene therapy in MRSA-caused bacterial keratitis is developed. This system employed rolling circle amplification to prepare DNA nanoflowers (DNFs) encoding MRSA-specific aptamers and mecR1 deoxyribozymes (DNAzymes). Subsequently, ß-lactam antibiotic ampicillin (Amp) and zinc oxide (ZnO) nanoparticles are sequentially loaded into the DNFs (ZnO/Amp@DNFs). Upon application, ZnO on the surface of the nanosystem disrupts the dense structure of biofilm and fully exposes free bacteria. Later, bearing encoded aptamer, the nanoflower system is intensively endocytosed by bacteria, and releases DNAzyme under acidic conditions to cleave the mecR1 gene for PBP2a down-regulation, and ampicillin for efficient MRSA elimination. In vivo tests showed that the system effectively cleared bacterial and biofilm in the cornea, suppressed proinflammatory cytokines interleukin 1ß ï¼ˆIL-1ß） and tumor neocrosis factor-alpha （TNF-α）, and is safe for corneal epithelial cells. Overall, this design offers a promising approach for treating MRSA-induced keratitis.

Restoring Ampicillin Sensitivity in Multidrug-Resistant Escherichia coli Following Treatment in Combination with Coffee Pulp Extracts.

Escherichia coli, particularly multidrug-resistant (MDR) strains, is a serious cause of healthcare-associated infections. Development of novel antimicrobial agents or restoration of drug efficiency is required to treat MDR bacteria, and the use of natural products to solve this problem is promising. We investigated the antimicrobial activity of dried green coffee (DGC) beans, coffee pulp (CP), and arabica leaf (AL) crude extracts against 28 isolated MDR E. coli strains and restoration of ampicillin (AMP) efficiency with a combination test. DGC, CP, and AL extracts were effective against all 28 strains, with a minimum inhibitory concentration (MIC) of 12.5-50 mg/ml and minimum bactericidal concentration of 25-100 mg/ml. The CP-AMP combination was more effective than CP or AMP alone, with a fractional inhibitory concentration index value of 0.01. In the combination, the MIC of CP was 0.2 mg/ml (compared to 25 mg/ml of CP alone) and that of AMP was 0.1 mg/ml (compared to 50 mg/ml of AMP alone), or a 125-fold and 500-fold reduction, respectively, against 13-drug resistant MDR E. coli strains. Time-kill kinetics showed that the bactericidal effect of the CP-AMP combination occurred within 3 h through disruption of membrane permeability and biofilm eradication, as verified by scanning electron microscopy. This is the first report indicating that CP-AMP combination therapy could be employed to treat MDR E. coli by repurposing AMP.

Antimicrobial, Antibiofilm Activities and Synergic Effect of Triterpene 3ß,6ß,16ß-trihydroxyilup-20(29)-ene Isolated from Combretum leprosum Leaves Against Staphylococcus Strains.

Antimicrobial resistance is a natural phenomenon and is becoming a huge global public health problem, since some microorganisms not respond to the treatment of several classes of antibiotics. The objective of the present study was to evaluate the antibacterial, antibiofilm, and synergistic effect of triterpene 3ß,6ß,16ß-trihydroxyilup-20(29)-ene (CLF1) against Staphylococcus aureus and Staphylococcus epidermidis strains. Bacterial susceptibility to CLF1 was evaluated by minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) assay. In addition, the effect combined with antibiotics (ampicillin and tetracycline) was verified by the checkerboard method. The biofilms susceptibility was assessed by enumeration of colony-forming units (CFUs) and quantification of total biomass by crystal violet staining. The compound showed bacteriostatic and bactericidal activity against all Staphylococcal strains tested. The synergistic effect with ampicillin was observed only for S. epidermidis strains. Moreover, CLF1 significantly inhibited the biofilm formation and disrupted preformed biofilm of the all strains. Scanning electron microscopy (SEM) images showed changes in the cell morphology and structure of S. aureus ATCC 700698 biofilms (a methicillin-resistant S. aureus strain). Molecular docking simulations showed that CLF1 has a more favorable interaction energy than the antibiotic ampicillin on penicillin-binding protein (PBP) 2a of MRSA, coupled in different regions of the protein. Based on the results obtained, CLF1 proved to be a promising antimicrobial compound against Staphylococcus biofilms.

Evaluation of efflux pump inhibitory activity of some plant extracts and using them as adjuvants to potentiate the inhibitory activity of some antibiotics against Staphylococcus aureus.

Background: Antibiotic-resistant pathogens became a real global threat to human and animal health. This needs to concentrate the efforts to minimize and control these organisms. Efflux pumps are considered one of the important strategies used by bacteria to exclude harmful materials from the cell. Inhibition of these pumps can be an active strategy against multidrug resistance pathogens. There are two sources of efflux pump inhibitors that can be used, chemical and natural inhibitors. The chemical origin efflux pump inhibitors have many toxic side effects while the natural origin is characterized by a wide margin of safety for the host cell. Aim: In this study, the ability of some plant extracts like (propolis show rosemary, clove, capsaicin, and cumin) to potentiate the inhibitory activity of some antibiotics such as (ciprofloxacin, erythromycin, gentamycin, tetracycline, and ampicillin) against Staphylococcus aureus pathogen were tested. Methods: Efflux pump inhibitory activity of the selected plant extracts was tested using an ethidium bromide (EtBr) accumulation assay. Results: The results have shown that Propolis has a significant synergistic effect in combination with ciprofloxacin, erythromycin, and gentamycin. While it has no effect with tetracycline or ampicillin. Also, no synergic effect was noticed in a combination of the minimum inhibitory concentration for the selected plant extracts (rosemary, clove, capsaicin, and cumin) with any of the tested antibiotics. Interestingly, according to the results of the EtBr accumulation assay, Propolis has potent inhibitory activity against the S. aureus (MRS usa300) pump system. Conclusion: This study suggests that Propolis might act as a resistance breaker that is able to restore the activity of ciprofloxacin, erythromycin, and gentamycin against S. aureus strains, in case of the efflux-mediated antimicrobial resistance mechanisms.

Functionalization of ampicillin and gentamicin with biogenic copper nanoparticles (CuNPs) remodel antimicrobial and cytotoxic outcome against MDR clinical isolates.

The present study reports the functionalization of antibiotic-conjugated Alternanthera pungens and Trichodesma indicum copper nanoparticles (CuNPs). Initially, antibiotic profiling of multi-drug resistant (MDR) clinical isolates against five antibiotics was verified and then gentamicin and ampicillin conjugates of CuNPs were prepared. Biosynthesized nanostructures were characterized through UV-visible spectroscopy, Fourier-transformed infrared spectroscopy, X-ray diffraction and scanning electron microscope. Biogenic synthesized CuNPs displayed highest antibacterial activity (24.0-31.3 mm inhibition zones) when capped with gentamicin as compared to the ampicillin-conjugated NPs which showed resistance against most of the bacterial species. A. pungens-derived conjugates of gentamicin (CuAp-GNT) along with the vehicle revealed 4.86 ± 0.20% and 4.25 ± 2.96% hemolytic potential and highest MDA production in S. typhimurium (3.18 ± 1.52 µg/mL and 6.31 ± 3.49 µg/mL) and K. pneumoniae (2.99 ± 0.90 µg/mL and 4.06 ± 1.20 µg/mL). Similarly, CuAp-GNT also showed highest DNA protection ability by displaying 1342.99 ± 11.87 band intensity. All-inclusive, CuAp showed more promising effects when conjugated with gentamicin indicating that capping of gentamicin with the active components of the plant-based copper nanostructures increases the antibacterial capacity of the drug. Hence, conjugation of antibiotics with bio-based sources offers great potential for identifying potent drug leads.

Green Extracellular Synthesis of Silver Nanoparticles by Pseudomonas alloputida, Their Growth and Biofilm-Formation Inhibitory Activities and Synergic Behavior with Three Classical Antibiotics.

Bacterial resistance to antibiotics is on the rise and hinders the fight against bacterial infections, which are expected to cause millions of deaths by 2050. New antibiotics are difficult to find, so alternatives are needed. One could be metal-based drugs, such as silver nanoparticles (AgNPs). In general, chemical methods for AgNPs' production are potentially toxic, and the physical ones expensive, while green approaches are not. In this paper, we present the green synthesis of AgNPs using two Pseudomonas alloputida B003 UAM culture broths, sampled from their exponential and stationary growth phases. AgNPs were physicochemically characterized by transmission electron microscopy (TEM), total reflection X-ray fluorescence (TXRF), infrared spectroscopy (FTIR), dynamic light scattering (DLS), and X-ray diffraction (XRD), showing differential characteristics depending on the synthesis method used. Antibacterial activity was tested in three assays, and we compared the growth and biofilm-formation inhibition of six test bacteria: Bacillus subtilis, Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, Staphylococcus aureus, and Staphylococcus epidermidis. We also monitored nanoparticles' synergic behavior through the growth inhibition of E. coli and S. aureus by three classical antibiotics: ampicillin, nalidixic acid, and streptomycin. The results indicate that very good AgNP activity was obtained with particularly low MICs for the three tested strains of P. aeruginosa. A good synergistic effect on streptomycin activity was observed for all the nanoparticles. For ampicillin, a synergic effect was detected only against S. aureus. ROS production was found to be related to the AgNPs' antibacterial activity.

Total Syntheses and Antibacterial Evaluations of Neocyclomorusin and Related Flavones.

Neocyclomorusin (1), a natural bioactive pyranoflavone mainly isolated from plants of the Moraceae family, was synthesized for the first time using a Friedel-Crafts reaction, a Baker-Venkataraman (BK-VK) rearrangement, a selective epoxidation, and a novel SN2-type cyclization as the key steps. The present protocol was also successfully applied for the total synthesis of oxyisocyclointegrin (2). Structurally related natural products morusin (23) and cudraflavone B (24) were also prepared. We investigated the antibacterial activities of these natural compounds against both Gram-negative and Gram-positive strains. The prenylated flavones, morusin (23) and cudraflavone B (24), showed comparable activity to ampicillin and kanacycin A against Staphylococcus aureus. Both morusin (23) and cudraflavone B (24) showed better antibacterial activities than ampicillin against the Gram-positive bacteria Staphylococcus epidermidis and Bacillus subtilis. Both neocyclomorusin (1) and oxyisocyclointegrin (2) displayed disappointing antimicrobial activities against Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis, and Bacillus subtilis strains.

GC/MS Composition and Resistance Modulatory Inhibitory Activities of Three Extracts of Lemongrass: Citral Modulates the Activities of Five Antibiotics at Sub-Inhibitory Concentrations on Methicillin-Resistant Staphylococcus aureus.

We investigated whether three extractable fractions of lemongrass (Cymbopogon citratus): aqueous and ethanol extracts and lemongrass essential oil exhibited any antimicrobial resistance modulatory effects if used in combination with selected antibiotics ampicillin, tetracycline, streptomycin, cefloxacin and amoxicillin on methicillin-resistant Staphylococcus aureus (MRSA). MRSA growth inhibition (zones of inhibition) was greatest for the lemongrass oil at concentrations of 1, 2, 5, 10 and 20 % (wt/vol). The MIC for lemongrass oil was 0.5 mg/mL, while it was 4 mg/mL for both the aqueous and ethanol extracts. Evaluation of extracts for antibacterial resistance modifying activities when used in combination with either of the five antibiotics at sub-inhibitory concentrations, showed that lemongrass oil highly potentiated the activities of three antibiotics; amoxicillin, streptomycin and tetracycline. The ethanol extract enhanced the activity of tetracycline and ampicillin, while the aqueous extract only increased the activity of tetracycline against MRSA. The activity of cefloxacin with the extracts was either indifferent. Analysis of the lemongrass oil by GC/MS showed the prominence of three compounds: the two isomers neral and geranial of citral and, the acetate geranyl acetate, which together made up 94 % of the composition. The compounds were also observed in the ethanol and water extracts but to a lesser extent when analyzed by HPLC-UV (λ 233 nm). Our study confirms the antibacterial properties of the extracts especially, lemongrass oil. It also demonstrates that lemongrass oil potentiates the activities of three antibiotics against the biofilm-forming MRSA. This biocidal, anti-biofilm disruption and antibiotic potentiating abilities are mainly attributable to citral and geranyl acetate, further evidence of lemongrass oil as a very useful source of phytochemicals, especially citral for the fight against antibiotic resistance.

[Rationality evaluation of Shuanghuanglian Injection combined with Ampicillin Sodium for Injection based on sequential analysis].

The lack of rationality evaluation method for drug combination has long restricted its clinical application. In view of this, this study took Shuanghuanglian Injection as model drug and established a "physical-chemical-biological" sequential analysis method, which is expected to provide clues for improving the safety and effectiveness of clinical drug combination. With the methods of insoluble particle testing, isothermal titration calorimetry(ITC), and real time cellular analysis(RTCA), the rationality of Shuanghuanglian Injection combined with Ampicillin Sodium for Injection was assessed. The results showed that the number of insoluble particles>10 µm in the solution of the combination met the standard of Chinese Pharmacopoeia, while the number of insoluble particles>25 µm did not meet the standard. ITC detection demonstrated that the change of Gibbs free energy(ΔG) was less than 0 during the fusion process, indicating that the process was spontaneous and enthalpy-driven reaction. Therefore, the interaction between the two was mainly chemical reaction, and the internal substances may change. RTCA found that Shuanghuanglian Injection alone and Ampicillin Sodium for Injection alone basically had no inhibitory effect on the growth of HEK293 T cells, while the combination of the two suppressed the growth of HEK293 T cells, suggesting that the combination was toxic to HEK293 T cells. This study showed that Shuanghuanglian Injection and Ampicillin Sodium for Injection reacted, yielding toxicity. This suggested that the two should not be combined for application. With the "physical-chemical-biological" sequential analysis, the molecular interaction of drugs was clarified. The method can be further applied for evaluating the rationality of other Chinese and western medicine injections.

Aminopenicillins for treatment of ampicillin-resistant enterococcal urinary tract infections.

PURPOSE: The purpose of this review is to describe the theory behind and data supporting use of aminopenicillins in the treatment of ampicillin-resistant enterococcal urinary tract infections. SUMMARY: Aminopenicillin concentrations in the urine may be high enough to achieve bacterial eradication and clinical cure for infections affecting the lower genitourinary tract, even in the context of in vitro resistance based on established susceptibility breakpoints. A literature search was conducted to identify original research articles describing the use of aminopenicillins in the treatment of urinary tract infections caused by ampicillin-resistant Enterococcus species. Three published retrospective cohort studies were identified, all of which reported that aminopenicillins had similar rates of clinical cure as other antibiotic classes prescribed for the treatment of enterococcal urinary tract infections. CONCLUSION: Both pharmacokinetic/pharmacodynamic principles and limited retrospective clinical data support the use of aminopenicillins in the treatment of lower urinary tract infections caused by Enterococcus species, even when the isolates have a minimum inhibitory concentration that exceeds the susceptibility breakpoint.

Phytochemical and anti-MRSA constituents of Zanthoxylum nitidum.

Infectious diseases caused by multidrug-resistant bacteria such as methicillin-resistant Staphylococcus aureus, pose a significant threat to humanity. Persistent and repeated invasive infection with MRSA led to higher morbidity and mortality, and required comprehensive measures in treatment and prevention. Zanthoxylum nitidum (Roxb.) DC. is used as detoxifying, analgesic, and hemostatic herbal medicine for thousands of years. Previously pharmacological studies showed that Z. nitidum had antibacterial bioactivity, but only the MIC of a few compounds, crude extracts, and fractions were reported. In our ongoing endeavor to explore bioactive compounds, two new coumarins, 6-(3-oxo-butyl)-limettin (1) and toddalin I (2), and 24 known compounds were isolated from the roots of Z. nitidum, in which two isoquinoline alkaloids, 6-acetonyl-dihydrofagaridine (16) and 6-acetonyl-dihydrochelerythrine (17) showed anti-MRSA bioactivity in vitro and in vivo. Both 16 and 17 showed synergistic action with ampicillin, which decreased the MIC significantly, and both compounds had a significant ability to destroy bacterial biofilm combined with ampicillin. The combined administration showed a strong scavenging effect on the planktonic bacteria in vitro and cleared skin infection effectively in the model of wound infection in vivo. Furthermore, compound 16 inhibited the efflux of the drug by combining with ampicillin or EtBr, resulting in the MIC decreased obviously. Our investigation supported the traditional use of Z. nitidum in treating infections caused by bacteria, and might provide new natural products to reduce the use of antibiotics and the treatment of drug-resistance bacteria.

Synergistic interactions between artocarpin-rich extract, lawsone methyl ether and ampicillin on anti-MRSA and their antibiofilm formation.

Artocarpin-rich extract (ARE) was prepared using a green technology and standardized to contain 49·6% w/w artocarpin, while lawsone methyl ether was prepared using a green semi-synthesis. ARE, LME and ampicillin exhibited weak anti-MRSA activity with the MICs of 31·2-62·5 µg/ml. Based on the checkerboard assay, the synergistic interaction between ARE (0·03 µg/ml) and LME (0·49 µg/ml) against four MRSA isolates were observed with the fractional inhibitory concentration index (FICI) value of 0·008, while those of ARE (1·95-7·81 µg/ml) and ampicillin (0·49 µg/ml) as well as LME (0·49-1·95 µg/ml) and ampicillin (0·49 µg/ml) were 0·016-0·257. The time kill confirmed the synergistic interactions against MRSA with different degrees. The combination of ARE and LME as well as its combinations with ampicillin altered the membrane permeability of MRSA, which led to release of the intracellular materials. In addition, each compound inhibited the biofilm formation of standard MRSA (DMST 20654) and the clinical isolate (MRSA 1096). These findings suggested that cocktails containing ARE and LME might be used to overcome problems associated with MRSA. Additionally, the results implied that combination of either ARE or LME with available conventional antibiotic agents might be effective in countering these perilous pathogens.

Efficacy of empiric antibiotic treatment of late-onset neonatal sepsis caused by Enterobacteriaceae: A systematic review.

Neonatal sepsis is a serious condition, where an adequate empiric antibiotic treatment is crucial. The objective of this systematic review is to assess whether the World Health Organization's recommended treatment regime remains applicable for late-onset neonatal sepsis caused by Enterobacteriaceae, in the time of increased antimicrobial resistance. PubMed was searched for articles from 2009 to 2020. A total of 49 articles were eligible for inclusion. The review was carried out in accordance with PRISMA guidelines. For Klebsiella spp. 100, 68 and 63% of the studies found sensitivity to ampicillin, gentamicin and third-generation cephalosporin in <50% of the isolates. For Escherichia coli, the corresponding values were 88, 50 and 42% respectively, whilst for Enterobacter spp. 100, 70 and 94% of the studies found <50% sensitivity to these antibiotics. Overall, there is low sensitivity to all agents in the WHO's recommended empiric treatment regimes (WHO recommends ampicillin plus gentamicin as first-line treatment and third-generation cephalosporin as second-line treatment). A revised guideline for empiric antibiotic treatment of neonatal sepsis is urgently needed due to the increased threat of antimicrobial resistant Enterobacteriaceae causing neonatal sepsis.

Transcriptomics and methylomics study on the effect of iodine-containing drug FS-1 on Escherichia coli ATCC BAA-196.

Aim: Promising results on application of iodine-containing nano-micelles, FS-1, against antibiotic-resistant Escherichia coli was demonstrated. Materials & methods: RNA sequencing for transcriptomics and the complete genome sequencing by SMRT PacBio were followed by genome assembly and methylomics. Results & conclusion: FS-1-treated E. coli showed an increased susceptibility to antibiotics ampicillin and gentamicin. Cultivation with FS-1 caused gene expression alterations toward anaerobic respiration, increased anabolism and inhibition of many nutrient uptake systems. Main targets of iodine-containing particles were cell membrane structures causing oxidative, osmotic and acidic stresses. Identification of methylated nucleotides showed an altered pattern in the FS-1-treated culture. Possible role of transcriptional and epigenetic modifications in the observed increase in susceptibility to gentamicin and ampicillin were discussed.

Lay abstract New approaches of combatting drug-resistant infections are in demand as the development of new antibiotics is in a deep crisis. This study was set out to investigate molecular mechanisms of action of new iodine-containing nano-micelle drug FS-1, which potentially may improve the antibiotic therapy of drug-resistant infections. Iodine is one of the oldest antimicrobials and until now there were no reports on development of resistance to iodine. Recent studies showed promising results on application of iodine-containing nano-micelles against antibiotic-resistant pathogens as a supplement to antibiotic therapy. The mechanisms of action, however, remain unclear. The collection strain Escherichia coli ATCC BAA-196 showing an extended spectrum of resistance to ßß-lactam and aminoglycoside antibiotics was used in this study as a model organism. Antibiotic resistance patterns, whole genomes and total RNA sequences of the FS-1-treated (FS) and negative control (NC) variants of E. coli BAA-196 were obtained and analyzed. FS culture showed an increased susceptibility to antibiotics associated with profound gene expression alterations switching the bacterial metabolism to anaerobic respiration, increased anabolism, osmotic stress response and inhibition of many nutrient uptake systems. Nucleotide methylation pattern were identified in FS and NC cultures. While the numbers of methylated sites in both genomes remained similar, some peculiar alterations were observed in their distribution along chromosomal and plasmid sequences.