Antibacterial activity of medicinal herb extracts against Salmonella

Therapeutic effects of Stemmoside C against Salmonella enterica serotype typhimurium infected BALB/c mice

Salmonella is a Gram-negative bacterium that causes gastrointestinal diseases in 20 to 40 million people globally. Stemmoside C is a steroidal glycoside isolated from Argel, although its antibacterial and antibiofilm properties have not been studied. The antibacterial activity of Stemmoside C against Salmonella enterica was revealed, where MIC of the compound was 16 μg/mL (0.15 µM). Biofilm-associated Stemmoside C treatment destroyed S. typhi cells and reduced viable S. typhi numbers below detectable levels. When compared to Stemmoside C or Ciprofluxacin-treated mice, infected BALB/c mice had a greater death rate and a larger bacterial blood burden. The protective effects of orally administered Stemmoside C at dose of 25 and 50 mg/kg b.wt. against bacterial infection was associated with reduction in the levels of inflammatory cytokines (IFN-γ, Il-1β, IL-2, IL-6, MPO, and TNF-α) and elevation of anti-inflammatory cytokine (IL-10 and IL-12) in serum. Where, Stemmoside C at dose of 50 mg/kg b.wt. regulated the levels almost as normal control group and demonstrated apparently normal intestinal sections. It also resulted in a decrease in the number of viable S. typhi retrieved from feces. Stemmoside C is a promising drug for the treatment or prevention of S. typhimurium infection.

Antimicrobial Compounds in Food Packaging

This review presents current knowledge on antimicrobial agents that are already used in the food packaging industry. At the beginning, innovative ways of food packaging were discussed, including how smart packaging differs from active packaging, and what functions they perform. Next, the focus was on one of the groups of bioactive components that are used in these packaging, namely antimicrobial agents. Among the antimicrobial agents, we selected those that have already been used in packaging and that promise to be used elsewhere, e.g., in the production of antimicrobial biomaterials. Main groups of antimicrobial agents (i.e., metals and metal oxides, organic acids, antimicrobial peptides and bacteriocins, antimicrobial agents of plant origin, enzymes, lactoferrin, chitosan, allyl isothiocyanate, the reuterin system and bacteriophages) that are incorporated or combined with various types of packaging materials to extend the shelf life of food are described. The further development of perspectives and setting of new research directions were also presented.

Antimicrobial Effects of Aqueous Extract from Calyces of Hibiscus sabdariffa in CD-1 Mice Infected with Multidrug-Resistant Enterohemorrhagic Escherichia coli and Salmonella Typhimurium

To determinate the antimicrobial effect of chloramphenicol and aqueous extract against multidrug-resistant enterohemorrhagic Escherichia coli (EHEC) and Salmonella enterica serovar Typhimurium in CD-1 mice. Aqueous extract was isolated from Hibiscus sabdariffa calyces. The minimum inhibitory concentration (MIC) and the minimum bactericidal concentration (MBC) of chloramphenicol and aqueous extract were determined for EHEC and S. Typhimurium. Nine groups of six mice each were formed. Three groups were inoculated orally with 1 × 10⁴ colony-forming units (CFU) of S. Typhimurium, three groups were inoculated with 1 × 10⁴ CFU of EHEC and the remaining three groups were not inoculated. Six hours postinoculation, the mice of some groups were orally administered solutions of aqueous extract (50 mg/mL), chloramphenicol (82 μg/mL), or isotonic saline. The EHEC and S. Typhimurium concentration in all mice feces was determined. For both pathogens, the MIC and MBC values of aqueous extract were 20 y 50 mg/mL, respectively; for chloramphenicol, they were between 17.5 and 82 μg/mL. EHEC and S. Typhimurium were not detected in the feces of mice that were administered aqueous extract on the 2nd and 3rd days posttreatment. Furthermore, these mice recovered from the infection. In contrast, in mice not treated, or treated with chloramphenicol alone, pathogens were isolated from their feces throughout the study, and some mice died. The H. sabdariffa calyx extracts could be an alternative to control multidrug-resistant bacteria in humans and animals.

Challenges to antimicrobial susceptibility testing of plant-derived polyphenolic compounds

As multidrug resistance gains momentum, the last two decades have seen an ever-growing interest in the antimicrobial properties of plant extracts and plant-derived compounds. Most of the focus is on polyphenols – a large and diverse group of phytochemicals with strong antibacterial activity. Testing methods provide reliable results as long as they follow standard procedures. However, methods and procedures used in antimicrobial susceptibility testing (AST) are often too diverse to allow comparison of results. The lack of uniformity and comparability is much owed to the absence of guidelines. The focus of this review is to give a critical overview of different methods used in the assessment of polyphenols antimicrobial efficacy and to highlight the importance of their standardisation.

Cyanobacteria and Microalgae as Sources of Functional Foods to Improve Human General and Oral Health

In the scenario of promising sources of functional foods and preventive drugs, microalgae and cyanobacteria are attracting global attention. In this review, the current and future role of microalgae as natural sources of functional foods for human health and, in particular, for oral health has been reported and discussed in order to provide an overview on the state of art on microalgal effects on human oral health. It is well known that due to their richness in high-valuable products, microalgae offer good anti-inflammatory, antioxidant, antitumoral, anti-glycemic, cholesterol-lowering, and antimicrobial activity. Moreover, the findings of the present research show that microalgae could also have a significant impact on oral health: several studies agree on the potential application of microalgae for oral cancer prevention as well as for the treatment of chronic periodontitis and different oral diseases with microbial origin. Thus, beneficial effects of microalgae could be implemented in different medical fields. Microalgae and cyanobacteria could represent a potential natural alternative to antibiotic, antiviral, or antimycotic therapies, as well as a good supplement for the prevention and co-adjuvant treatment of different oral diseases. Nevertheless, more studies are required to identify strains of interest, increase overall functioning, and make safe, effective products available for the whole population.

Nematodes trophic groups changing via reducing of bacterial population density after sediment enrichment to ciprofloxacin antibiotic: Case study of Marine Mediterranean community

An experiment was carried out using microcosms to evaluate the impact of the fluoroquinolone antibiotic on nematode trophic groups structure and bacterial abundance. Sediment samples were experimentally enriched with four increasing doses of ciprofloxacin [D1 (50 ppm), D2 (100 ppm), D3 (200 ppm) and D4 (500 ppm)] and compared to non-enriched sediments (used as control). Ciprofloxacin changed the trophic composition of nematodes taxa where the relative abundance of microvores (M), epigrowth feeders (EF) and ciliate consumers (CF), raised in a control microcosm, was highly affected and significantly decreased in response to the increasing doses. Nevertheless, the abundance of deposit feeders (DF), optional predators (FP) and exclusive predators (Pr) showed a significant increase. Results from the multivariate analysis showed a clear impact of this antibiotic on nematode trophic assemblages. Microcosms treated with the three highest doses [D2, D3 and D4] were different from the control. The exceptions were those treated with the lowest dose, D1, and which were grouped with the control. The SIMPER analysis results showed that the average dissimilarity continuously increased in the treated microcosms compared to the control. Furthermore, our results have shown that ciprofloxacin also leads to a significant decrease in bacterial density with the highest dose, which could explain the results obtained for nematode trophic groups distribution. Thus, the bacteriophages nematodes only use bacteria as a nutrition source and the lack or presence in small quantity of this food could induce a decrease in their abundance as well as changing of nematodes groups repartition. Our work demonstrates that the nematode responses were dependent on sediment enrichment with ciprofloxacin and opens new perspectives on the potential impact of antibiotics on functional nematode diversity.

The Role of Silver Nanoparticles in a Treatment Approach for Multidrug-Resistant Salmonella Species Isolates

PURPOSE

The main objective of this study is to investigate the antibacterial activity of silver nanoparticles (AgNPs) against multidrug-resistant Salmonella isolates recovered from diarrheic  sheep and goats.

METHODS

This study used chemical reduction synthesis of AgNPs to evaluate their antimicrobial effects by estimation of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) for each isolate using the microplate dilution method and tetrazolium salt reduction test to detect the viability percentage. In vivo treatment efficacy was assessed in mice by determining the viable count of Salmonella Enteritidis recovered from feces and by hematologic, biochemical and histopathologic examinations to confirm that use of AgNPs has no toxic or pathologic effects and to evaluate its ability in tissue regeneration following treatment.

RESULTS

All recovered strains were identified as MDR with a prevalence of 4% and 3.6% in sheep and goats, respectively. The results of TEM, DLS, Zeta potential, and FTIR revealed typical characteristics of the synthesized AgNPs. Silver nanoparticles showed antibacterial activity against all recovered strains with MIC of ≤0.02-0.313 μg/mL (mean average 0.085±0.126 μg/mL) and MBC of 0.078-1.250 μg/mL (average 0.508±0.315 μg/mL). In vivo efficacy of AgNPs was observed by a reduction in the number of viable S. Enteritidis recovered from feces in an S. Enteritidis infected mouse model, with complete shedding stopping between treatment days 4 and 6. Hematologic, serum biochemical, and histopathologic analyses proved the ability of AgNPs to suppress inflammatory reaction caused by S. Enteritidis infection.

CONCLUSION

The study proved the effective ability of AgNPs to fight MDR Salmonella spp. in vitro and in vivo without adverse effects.

Understanding the Molecular Mechanisms of the Interplay Between Herbal Medicines and Gut Microbiota

Herbal medicines (HMs) are much appreciated for their significant contribution to human survival and reproduction by remedial and prophylactic management of diseases. Defining the scientific basis of HMs will substantiate their value and promote their modernization. Ever-increasing evidence suggests that gut microbiota plays a crucial role in HM therapy by complicated interplay with HM components. This interplay includes such activities as: gut microbiota biotransforming HM chemicals into metabolites that harbor different bioavailability and bioactivity/toxicity from their precursors; HM chemicals improving the composition of gut microbiota, consequently ameliorating its dysfunction as well as associated pathological conditions; and gut microbiota mediating the interactions (synergistic and antagonistic) between the multiple chemicals in HMs. More advanced experimental designs are recommended for future study, such as overall chemical characterization of gut microbiota-metabolized HMs, direct microbial analysis of HM-targeted gut microbiota, and precise gut microbiota research model development. The outcomes of such research can further elucidate the interactions between HMs and gut microbiota, thereby opening a new window for defining the scientific basis of HMs and for guiding HM-based drug discovery.

Coptidis rhizome and Si Jun Zi Tang can prevent Salmonella enterica serovar Typhimurium infection in mice

Salmonella, a common zoonotic pathogen, causes gastroenteritis in both humans and animals. Traditional Chinese Medicine (TCM) has been used to improve gastrointestinal dysfunction and to modify the immune response to inflammation for centuries. This study used six herbal plants and four TCM formulae to rate their efficacy in preventing S. Typhimurium infection via mouse model. Minimum bactericidal concentration (MBC) of Coptidis rhizome (CR) against the reference strain tallied 12.5 mg/ml and against clinical isolate ST21 was 25 mg/ml. MBCs of other herbal extracts and formulae on Salmonella Typhimurium strains were above 50 mg/ml. In the mice model, CR and Si Jun Zi Tang (SJZT) could significantly decrease the bacterial load in organs and blood after being challenged, along with body weight loss due to the infection. CR and SJZT alleviated infection-induced interferon-gamma levels in the serum and tissues, and tumor necrosis factor-alpha (TNF-α) levels in intestinal tissues. CR and SJZT serum metabolites could suppress S. Typhimurium invasion and TNF-α expression in RAW264.7 cells. The therapeutic activity of CR and SJZT may involve berberine, ginsenoside Rb1, and glycyrrhizin, interfering with Salmonella when invading macrophages. CR and SJZT has shown potential in preventing S. Typhimurium infection through the regulation of the immune response.

Methyl gallate from Galla rhois successfully controls clinical isolates of Salmonella infection in both in vitro and in vivo systems

Galla rhois is a commonly used traditional medicine for the treatment of pathogenic bacteria in Korea as well as in other parts of Asia. Methyl gallate (MG), a major component of Galla Rhois, exhibits strong antibacterial activity, but its mechanism of action against Salmonella spp. is unclear. In the present study, we investigated the antibacterial actions of MG against Salmonella. The antibacterial activity determined by broth dilution method indicated that the antibacterial activity of MG against Salmonella strains ranged from 3.9 to 125 µg/ml. In vitro bacterial viability test indicated that MG significantly decreased the viability of Salmonella over 40% when combined with ATPase inhibitors. The time-kill curves showed that a combined MG and ATPase inhibitors (DCCD and NaN3) treatment reduced the bacterial counts dramatically after 24 h. Oral administration of MG showed a strong anti-bacterial activity against WS-5 infected BALB/c mice. In contrast to the untreated Salmonella infected control animals, MG treated groups showed no clinical symptoms of the disease, such as lethargy and liver damage. It was observed that MG treatment significantly increased the survival of animals from Salmonella infection, while in untreated groups all animal succumbed to disease by the sixth day post infection. Thus, the present study demonstrates the therapeutic ability of MG against Salmonella infections.

Herbal therapy is equivalent to rifaximin for the treatment of small intestinal bacterial overgrowth

OBJECTIVE

Patients with small intestine bacterial overgrowth (SIBO) have chronic intestinal and extraintestinal symptomatology which adversely affects their quality of life. Present treatment of SIBO is limited to oral antibiotics with variable success. A growing number of patients are interested in using complementary and alternative therapies for their gastrointestinal health. The objective was to determine the remission rate of SIBO using either the antibiotic rifaximin or herbals in a tertiary care referral gastroenterology practice.

DESIGN

One hundred and four patients who tested positive for newly diagnosed SIBO by lactulose breath testing (LBT) were offered either rifaximin 1200 mg daily vs herbal therapy for 4 weeks with repeat LBT post-treatment.

RESULTS

Three hundred ninety-six patients underwent LBT for suspected SIBO, of which 251 (63.4%) were positive 165 underwent treatment and 104 had a follow-up LBT. Of the 37 patients who received herbal therapy, 17 (46%) had a negative follow-up LBT compared to 23/67 (34%) of rifaximin users (P=.24). The odds ratio of having a negative LBT after taking herbal therapy as compared to rifaximin was 1.85 (CI=0.77-4.41, P=.17) once adjusted for age, gender, SIBO risk factors and IBS status. Fourteen of the 44 (31.8%) rifaximin non-responders were offered herbal rescue therapy, with 8 of the 14 (57.1%) having a negative LBT after completing the rescue herbal therapy, while 10 non-responders were offered triple antibiotics with 6 responding (60%, P=.89). Adverse effects were reported among the rifaximin treated arm including 1 case of anaphylaxis, 2 cases of hives, 2 cases of diarrhea and 1 case of Clostridium difficile. Only one case of diarrhea was reported in the herbal therapy arm, which did not reach statistical significance (P=.22).

CONCLUSION

SIBO is widely prevalent in a tertiary referral gastroenterology practice. Herbal therapies are at least as effective as rifaximin for resolution of SIBO by LBT. Herbals also appear to be as effective as triple antibiotic therapy for SIBO rescue therapy for rifaximin non-responders. Further, prospective studies are needed to validate these findings and explore additional alternative therapies in patients with refractory SIBO.

Review: Chinese herbs as alternatives to antibiotics in feed for swine and poultry production: Potential and challenges in application

Gong, J., Yin, F., Hou, Y. and Yin, Y. 2014. Chinese herbs as alternatives to antibiotics in feed for swine and poultry production: Potential and challenges in application. Can. J. Anim. Sci. 94: 223–241. Traditional Chinese medicine (TCM) has a long history of clinical practice, and its own theoretical framework focused on functions at the whole-body level. However, due to cultural differences, TCM has not been fully recognized in Western countries. With the recent development of the theory of whole-body systems biology and “-omics”, there is a new opportunity to study TCM and to close the gap between TCM and Western medicine, because of the similarity in the theoretical foundations between TCM and whole-body systems biology. The uniqueness of TCM theory and practice is the approach to maintain and restore the body balance as a whole with no or little unfavourable side effects. Recent studies have also shown that Chinese herbs used as feed additives can modulate nutritional metabolism, immune responses, and intestinal health of food-producing animals, demonstrating good potential as substitutes for dietary antibiotics. Nonetheless, some issues need to be addressed before Chinese herbs can reach their full application. This article has critically reviewed recent progresses in scientific research of Chinese herbs as feed additives and their potential to replace dietary antibiotics. Possible challenges in future application for swine and poultry production are also discussed.

Synergistic effect and antiquorum sensing activity of Nymphaea tetragona (water lily) extract

Salmonellosis is a common and widely distributed food borne disease where Salmonella typhimurium is one of the most important etiologic agents. The purpose of this study was to investigate the antimicrobial activity of Nymphaea tetragona alone and in combination with antibiotics against S. typhimurium. It also aimed to assess the plant for quorum sensing inhibition (QSI) activity and to identify the bioactive compounds. The antibacterial activities of the extract were assessed using broth microdilution method. Disk agar diffusion method was employed to determine the QSI and bioactive compounds were identified by GC-MS analysis. Ethyl acetate fraction of N. tetragona extract (EFNTE) demonstrated good antimicrobial activity (MIC 781 μg/mL) against 4 strains out of 5. FIC index ranged from 0.375 to 1.031 between EFNTE/tylosin and 0.515 to 1.250 between EFNTE/streptomycin against S. typhimurium. Among all extracts, EFNTE and butanol fraction more significantly inhibited pigment production of C. violaceum. Polyphenols were identified as major compound of EFNTE and butanol fraction. These results indicate that combination among N. tetragona extract and antibiotics could be useful to combat drug-resistance Salmonella infections and polyphenols are promising new components from N. tetragona that warrant further investigation as a candidate anti-Salmonella agent and quorum sensing inhibitor.

Antimicrobial activity of food-compatible plant extracts and chitosan against naturally occurring micro-organisms in tomato juice

BACKGROUND

Chitosan (AC) and five hydroalcoholic extracts from Lithospermum erythrorhizon (SE), Rheum palmatum (RE), Thymus vulgaris (AT), Lippia citriodora (PLX) and a mixture of Rosmarinus officinalis, Salvia lavandulifolia and Thymus mastichina (LA) were tested for antimicrobial activity against bacteria, yeasts and filamentous fungi using two broth dilution methods. The effects of adding single extracts on naturally occurring micro-organisms and sensory qualities of raw tomato juice were also evaluated.

RESULTS

SE extract exhibited the strongest activity, with minimum inhibitory concentrations (MICs) of 100-400 µg mL⁻¹ for Gram-positive and 1600-3200 µg mL⁻¹ for Gram-negative bacteria. Enterobacter aerogenes showed the greatest susceptibility to AC (MIC 1600 µg mL⁻¹). Lethal effects of extracts and AC were achieved at a minimum bactericidal concentration (MBC)/MIC ratio of 2 in 88% of assays. SE and RE extracts and AC also exhibited antifungal effect against yeasts, but they had no activity on filamentous fungi. Control and 100 mg L⁻¹ SE-added tomato juices did not differ in acceptance, but this SE concentration was not effective in the control of microbial load throughout cold storage.

CONCLUSION

Results confirm the antimicrobial potential of the plant extracts, but additional research is needed until the agents responsible for the activities have been determined in order to use them as natural constituents of multiple-barrier food preservation systems.

In Vitro and In Vivo Antibacterial Activity of Punica granatum Peel Ethanol Extract against Salmonella

Punica granatum is commonly used in Korea as a traditional medicine for the treatment of pathogenic bacteria. In this study, we investigated the in vitro and in vivo antimicrobial activity of P. granatum peel EtOH extract (PGPE) against 16 strains of Salmonella. The minimal inhibitory concentrations of PGPE were in the range of 62.5–1000 x03BCg mL⁻¹. In addition, the in vivo antibacterial activity of the PGPE extract was examined in a S. typhimurium infection mouse model. Mice were initially infected with S. typhimurium and then with PGPE. The extract was found to have significant effects on mortality and the numbers of viable S. typhimurium recovered from feces. Although clinical signs and histological damage were rarely observed in the treated mice, the untreated controls showed signs of lethargy and histological damage in the liver and spleen. Taken together, the results of this study indicate that PGPE has the potential to provide an effective treatment for salmonellosis.

Antimicrobial activity of a combination of Mume fructus, Schizandrae fructus, and Coptidis rhizoma on enterohemorrhagic Escherichia coli O26, O111, and O157 and its effect on Shiga toxin releases

The antibacterial activity of an herbal combination composed of Mume Fructus, Coptidis Rhizoma, and Schizandrae Fructus extracts on enterohemorrhagic Escherichia coli (EHEC) was evaluated in the present study. The combination demonstrated antibacterial activity against all EHEC strains tested in this study, including those resistant to multiple antibiotics; minimum inhibitory concentration values ranged from 0.49 to 31.25 mg/mL. In in vivo antibacterial activity assay, the herbal combination was administered to mice after initial E. coli O157 infection and had significant effects on mouse mortality. The effects of the herbal combination on Shiga toxin release from EHEC O26, EHEC O111, and EHEC O157 strains containing the stx1 and stx2 genes were assessed by the reversed passive latex agglutination method, and there was no increased Shiga toxin release in the strain cultures containing the herbal combination. These results suggested that the herbal combination may be a safe and effective remedy for EHEC inhibition.

Future possibilities for the treatment of septic shock with herbal components

The treatment of septic shock remains challenging even with the armamentarium of modern antibiotics and intensive care technologies. Reliance on antibiotics and other methods targeting modulation of the systemic inflammatory response such as steroids, hemofiltration, and cytokine antagonists has not led to reliable successful treatment for inflammation and infection-related shock. In part, this is attributable to the continuous evolution of antibacterial drug resistance. Herbal medicine has been used in treating infections and shock, worldwide, for thousands of years. The active components contained in these naturally occurring products usually have one or more of the following properties: (1) direct attack or suppression on bacterial pathogens, (2) modulation of the host's immune system resulting in suppression of inflammation and overproduction of inflammatory mediators, and (3) neutralization of toxic free-radicals. In vitro and in vivo animal and human clinical studies of herbal medicines' effectiveness in the treatment of septic shock are needed. Their pharmacological mechanisms need to be elucidated at molecular level to investigate and improve targeted therapy using heretofore unexplored uses for traditional herbal remedies. Herein, we discuss historical examples of herbal remedies used to fight infection. In addition, we discuss the use of herbal and traditional medicines as potential adjuncts in the ongoing battle against septic shock and systemic infections.