Synergistic, additive, and antagonistic activity of antimicrobial agents: How to measure? What are the clinical consequences? Applications to the new fluoroquinolones

Despite the introduction of modern methods of treatment, the creation of new generations of antibacterial agents, and the constant improvement of aseptic and antiseptic methods, the treatment of purulent–inflammatory processes remains one of the most complex and urgent problems in veterinary practice. The article presents the results of the isolation of indigenous microbiota from various biotopes of healthy cats, as well as the study of their biological marker properties for the selection of the most optimal strains in probiotic medicines for the control of surgical infections. It was demonstrated that isolated cultures of bifidobacteria and lactobacilli, which we isolated, revealed high sensitivity to antibiotics of the β-lactam group (excepting L. acidophilus No. 24, L. plantarum “Victoria” No. 22, L. rhamnosus No. 5, L. rhamnosus No. 20, and L. rhamnosus No. 26, which showed a significant variability in sensitivity to antibacterial drugs of this group, indicating the great potential of these microorganisms) and resistance to aminoglycosides, lincosamides, and fluoroquinolones (with the exception of gatifloxacin, which showed high efficiency in relation to all lactic acid microorganisms). The adhesive properties of the isolated lactobacteria and bifidobacteria were variable, even within the same species. It was found that the B. adolescentis No. 23 strain of the Bifidobacterium genus, as well as the L. plantarum No. 8, L. plantarum “Victoria” No. 22, L. rhamnosus No. 6, L. rhamnosus No. 26, L. acidophilus No. 12, and L. acidophilus No. 24 strains of the Lactobacillus genus had the highest adhesive activity. Thus, when conducting a detailed analysis of the biological marker properties of candidate cultures (determining their sensitivity to antimicrobial agents, studying the adhesive properties, and antagonistic activity in relation to causative agents of surgical infection in cats), it was found that the most promising are L. plantarum “Victoria” No. 22, L. rhamnosus No. 26, and L. acidophilus No. 24.

Download Full-text

Evaluation of Native Wine Yeast as Biocontrol Agents Against Fungal Pathogens Related to Postharvest Diseases

10.20944/preprints201909.0113.v1 ◽

2019 ◽

Author(s):

Paula Reyes-Bravo ◽

Andrea Acuña-Fontecilla ◽

Ines Marlene Rosales ◽

Liliana Godoy

Keyword(s):

Biological Control ◽

Antimicrobial Agents ◽

Plant Protection ◽

Antagonistic Activity ◽

Penicillium Expansum ◽

In Vitro Assays ◽

Postharvest Diseases ◽

Antagonistic Microorganisms ◽

Chemical Products ◽

The Impact

Changes in consumer expectations have led to increasing demand for novel plant protection strategies, in order to reduce the application of chemical products, reduce the occurrence of new pests and the impact that all these actions generate in the environment. In recent years there have been numerous investigations related to biological control and the use of microorganisms as new control strategies. As part of integrated disease management, antagonistic microorganisms have been investigated lately and presented great interest. Such microorganisms can be applied in conventional and in organic farming as biological control agents (BCA). Many of these microorganisms are present in the microbial ecology generating interactive associations between surrounding microorganisms. For these reasons, it has become necessary to search new natural antimicrobial agents as alternatives to synthetic and chemical products. It has been discovered that there are microorganisms, particularly yeasts, that have antagonistic activity and different mechanisms of action, indicating that they could be interesting candidates for the development of BCA. Here, we evaluate the antagonist effect of four endophytic yeast, Cryptococcus antarcticus, Aureobasidium pullulans, Cryptococcus terrestris and Cryptococcus oeirensis over the growth of Botrytis cinerea, Monilinia laxa, Penicillium expansum and Geotrichum candidum in in vitro assays (inhibition zone diameter assay and confrontation assay).The results revealed that the four yeast strains evaluated showed antagonistic activity against the phytopathogens tested, suggesting that these yeasts produce compounds capable of inhibiting the growth of fungi and, depending on the assay, the evaluated antagonist-yeasts have differential biocontrolling-effect against the postharvest pathogens tested.

Download Full-text

Caves as a source of new antimicrobial agents: the case study of antibacterial activity from microorganisms inhabiting Cerâmica Cave, Portugal

ARPHA Conference Abstracts ◽

10.3897/aca.1.e30142 ◽

2018 ◽

Vol 1 ◽

Author(s):

André Gouveia ◽

Ana Sofia Reboleira ◽

Fernando Gonçalves ◽

Sérgio Marques

Keyword(s):

Antimicrobial Activity ◽

Antimicrobial Agents ◽

Extreme Environments ◽

Antagonistic Activity ◽

Aeromonas Salmonicida ◽

Drug Resistant ◽

Massif Central ◽

Dry Heat ◽

Track Record ◽

Stable Conditions

Antibiotics have been developed for more than 80 years but presently there is an evident decline on their effectiveness due to the development of resistance by pathogens. The arising of multi drug resistant pathogens, has become a serious threat to public health. Microorganisms play a central role in nature as well as in drug discovery with a long track record as important sources of bioactive natural products revealing a wide array of molecules. Although many approaches have been applied to solve this crisis, in the last decades the focus on extreme habitats as gain attention due to peculiar features and due to the presence of unique microbial populations inhabiting these ecosystems. Caves are considered extreme environments, usually oligotrophic, being in general devoid of light, and presenting stable conditions (temperature, humidity) throughout the year. We present the first analysis of antimicrobial activity of bacteria isolated from Cerâmica Cave, located in the Sicó karst massif, central Portugal. Microorganism acquisition was performed through a variety of physical and chemical treatments: dry-heat, wet-heat, dry-heat plus phenol (1,5%), phenol (1,5%), microwave irradiation, rehydration centrifugation, and no-treatment, along with three media: R2A agar, Actinomycetes isolation agar and Yeast-malt agar. A primary antimicrobial activity screening, through cross streak method, was performed in 28 isolates, using two different incubation periods and different target agents (Staphylococcus aureus, Bacillus cereus, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Aeromonas salmonicida, Salmonella typhimurium and Enterococcus faecalis). A total of 7 isolates presented antagonistic activity against B. cereus, P. aeruginosa, E. coli, A. salmonicida S. typhimurium and S. aureus. This study proves the ability of cave microorganisms to inhibit both Gram positive and Gram negative pathogenic strains, highlighting the potential of caves microbiome to be one of the answers to solve the current global crisis of multi drug resistant pathogens.

Download Full-text

The need for individual selection of probiotics containing lactobacilli and enterococci to increase the effectiveness of therapy for campylobacteriosis

Experimental and Clinical Gastroenterology ◽

10.31146/1682-8658-ecg-186-2-88-93 ◽

2021 ◽

pp. 88-93

Author(s):

K. D. Ermolenko ◽

N. P. Boldyreva ◽

E. A. Martens ◽

L. I. Zhelezova ◽

S. V. Sidorenko ◽

...

Keyword(s):

Antimicrobial Agents ◽

Specific Activity ◽

High Sensitivity ◽

Saccharomyces Boulardii ◽

Antagonistic Activity ◽

Individual Selection ◽

Treatment Regimens ◽

Campylobacter Spp ◽

Selection Of

The article highlights the problem of improving the rational treatment of campylobacteriosis. Probiotics are present in treatment regimens along with antibiotics, which have the advantage that they do not violate intestinal microbiocenosis and provide the ability to correct dysbiotic conditions. As well as antimicrobial agents, probiotics have different effects on the growth of pathogenic microorganisms. Campylobacter spp. probiotics in the in vitro system. The article studies the anticampylobacter activity of probiotic cultures of Enterococcus faecium L3, Lactobacillus plantarum 8 R-A3, a mixture of Lactobacillus acidophilus and Saccharomyces boulardii by two-layer agar and droplet method. Analysis of the antagonistic activity of chemically synthesized bacteriocins. The high sensitivity of Campylobacter spp was presented. to probiotics having lactobacilli and enterococci, as well as their metabolites (including bacteriocins). The strain-specific activity of probiotics and its dependence on their ability to produce bacteriocins were found. The results and data of other researchers indicate the need for individual selection of probiotics for the treatment of campylobacteriosis, the feasibility of analyzing the bacteriocinogenicity of the strains and testing their effect on the growth of clinical isolates.

Download Full-text

Antagonistic Activity ofLactobacillusIsolates againstSalmonella typhi In Vitro

BioMed Research International ◽

10.1155/2013/680605 ◽

2013 ◽

Vol 2013 ◽

pp. 1-12 ◽

Cited By ~ 14

Author(s):

Amira Abdel-Daim ◽

Nadia Hassouna ◽

Mohamed Hafez ◽

Mohamed Seif Aldeen Ashor ◽

Mohammad M. Aboulwafa

Keyword(s):

Typhoid Fever ◽

Lactobacillus Plantarum ◽

Antimicrobial Agents ◽

Salmonella Typhi ◽

Antagonistic Activity ◽

Oxygen Tolerance ◽

Probiotic Potential ◽

Concurrent Use

Background. Enteric fever is a global health problem, and rapidly developing resistance to various drugs makes the situation more alarming. The potential use ofLactobacillusto control typhoid fever represents a promising approach, as it may exert protective actions through various mechanisms.Methods. In this study, the probiotic potential and antagonistic activities of 32Lactobacillusisolates againstSalmonella typhiwere evaluated. The antimicrobial activity of cell free supernatants ofLactobacillusisolates, interference ofLactobacillusisolates with theSalmonellaadherence and invasion, cytoprotective effect ofLactobacillusisolates, and possibility of concurrent use of testedLactobacillusisolates and antibiotics were evaluated by testing their susceptibilities to antimicrobial agents, and their oxygen tolerance was also examined.Results. The results revealed that twelveLactobacillusisolates could protect againstSalmonella typhiinfection through interference with both its growth and its virulence properties, such as adherence, invasion, and cytotoxicity. TheseLactobacillusisolates exhibited MIC values for ciprofloxacin higher than those ofSalmonella typhiand oxygen tolerance and were identified asLactobacillus plantarum.Conclusion. The testedLactobacillus plantarumisolates can be introduced as potential novel candidates that have to be subjected forin vivoand application studies for treatment and control of typhoid fever.

Download Full-text