Multidrug-resistant Clinical Pathogens Research Articles

Antimicrobial evaluation of spirooxindolopyrrolidine engrafted indoles against multidrug resistant ESKAPE clinical pathogens

The synthesis of a new class of effective antibiotics and antimicrobial agents with less toxicity is highly desirable due to bacterial resistance to antibiotics has increased dramatically. In this context, molecules that embedding a spiro moiety are attractive from a medicinal chemistry point of view as these spiro heterocycles show a vital part in the development of delivery systems for antimicrobial therapies. In the present study, the synthesis and antimicrobial evaluation of structurally attractive complex hybrid heterocycles comprising spriooxindolopyrrolidine and indole heterocycles was attained in quantitative yields by cycloaddition strategy. The new class of spirocompouds were unequivocally assigned through spectroscopic analysis and the antimicrobial efficacy were assessed against six microbial pathogens. Among them, compound 4a, bearing chlorine substituted derivative showed significant activity against tested ESKAPE pathogens. The maximum zone of inhibition observed against ESKAPE microbial pathogens causing infectious disease ranged from 6.75 ± 0.40 to 19.75 ± 1.15 mm, with MIC values ranging between 16.00 to > 256.00 µg/ml .

Rosmarinus officinalis essential oils’ eradication of beta-lactamase and multidrug resistant clinical bacterial pathogens from hospital settings

Antibiotics have become increasingly ineffective in the face of bacterial resistance, particularly in hospitals. Interestingly, there is high demand for bioprospecting of secondary metabolites, particularly for treating multidrug-resistant clinical diseases. In fact, Rosemary has been used for its antiseptic properties dating back to antiquity. The aim of this research is to evaluate the effectiveness of Rosmarinus officinalis essential oil against multidrug-resistant clinical bacterial pathogens. Results showed promising antibacterial activity against seven bacteria: Escherichia coli, Enterobacter cloacae, Staphylococcus aureus, Serratia odorifera, Klebsiella pneumoniae, Klebsiella oxytoca, Aeromonas hydrophila with MIC values of 35.7, 17.85, 71.4, 8.9, 17.8, 285.7, 35.7 µg/ml respectively and MBC values of 142.8, 71.4, 285.7, 35.7, 71.4, 571.5,71.4 µg/ml respectively. This study suggests that Rosmarinus essential oil can be used as a therapeutic agent in the fight against a wide range of multi-resistant bacteria.

Metagenomic insights into the microbial community structure and resistomes of a tropical agricultural soil persistently inundated with pesticide and animal manure use.

Persistent use of pesticides and animal manure in agricultural soils inadvertently introduced heavy metals and antibiotic/antibiotic resistance genes (ARGs) into the soil with deleterious consequences. The microbiome and heavy metal and antibiotic resistome of a pesticide and animal manure inundated agricultural soil (SL6) obtained from a vegetable farm at Otte, Eiyenkorin, Kwara State, Nigeria, was deciphered via shotgun metagenomics and functional annotation of putative ORFs (open reading frames). Structural metagenomics of SL6 microbiome revealed 29 phyla, 49 classes, 94 orders, 183 families, 366 genera, 424 species, and 260 strains with the preponderance of the phyla Proteobacteria (40%) and Actinobacteria (36%), classes Actinobacteria (36%), Alphaproteobacteria (18%), and Gammaproteobacteria (17%), and genera Kocuria (16%), Sphingobacterium (11%), and Brevundimonas (10%), respectively. Heavy metal resistance genes annotation conducted using Biocide and Metal Resistance Gene Database (BacMet) revealed the detection of genes responsible for the uptake, transport, detoxification, efflux, and regulation of copper, cadmium, zinc, nickel, chromium, cobalt, selenium, tungsten, mercury, and several others. ARG annotation using the Antibiotic Resistance Gene-annotation (ARG-ANNOT) revealed ARGs for 11 antibiotic classes with the preponderance of β-lactamases, mobilized colistin resistance determinant (mcr-1), macrolide-lincosamide-streptogramin (MLS), glycopeptide, and aminoglycoside resistance genes, among others. The persistent use of pesticide and animal manure is strongly believed to play a major role in the proliferation of heavy metal and antibiotic resistance genes in the soil. This study revealed that agricultural soils inundated with pesticide and animal manure use are potential hotspots for ARG spread and may accentuate the spread of multidrug resistant clinical pathogens.

In-Vitro evaluation of antimicrobial activity of Allium sativum and Zingiber Officinale against multi-drug resistant clinical pathogens.

Background: Clinically significant microbes have evolved over time and developed such mechanisms to protect themselves from synthetic drugs. This study aims to determine the antimicrobial activity of culinary condiments against multi-drug resistant clinical pathogens. Methodology: The antimicrobial activity of Allium sativum (garlic) and Zingiber Officinale (ginger) was assessed against clinical pathogens such as E. coli, P. aeruginosa, and S. aureus. with the aid of wet experiments, namely disc diffusion method, and well agar technique. Results: It was observed that both A. sativum and Z. officinale in their neat form were very effective against tested pathogens ranges from 16 ± 0.623 mm to 36 ± 0.816 mm and 19 ± 0.707 to 20 ± 1.414 mm respectively as compared to the other concentrations with peptone water and distal water. However, extract A. sativum showed more antibacterial strength than Z. officinale. Conclusion: Natural antimicrobial agents obtained from herbs and spices could be effective alternatives to treat various infections with minimum to no side effects.

Development and evaluation of Zhumeria majdae essential oil-loaded nanoliposome against multidrug-resistant clinical pathogens causing nosocomial infection

In this study, we used Zhumeria majdae essential oil (ZMEO) loaded nanoliposome (NLP) to control several multidrug-resistant clinical pathogens (MDRs) that cause nosocomial infections using thin-layer hydration. Initially, ZMEO was extracted and analyzed by GC-MS, and then NLP-ZMEO was examined with different ratios of ZMEO to lecithin. Based on evaluation of release profile and physical stability, size distribution, and particle size, using dynamic light scattering (DLS) results, the most stable NLP-ZMEO were prepared from ZMEO to lecithin ratio 1:3 that relative to pure ZMEO presented more potent antioxidant, anti-quorum sensing, and anti-biofilm activities. The morphology results (AFM and SEM) also agreed with DLS analysis. Also, the results of structural properties (DSC and FTIR) approved interaction between ZMEO and NLP. Comparing the cytotoxic effect on fibroblasts cell lines and antibacterial activity (MIC, MBC, and agar disc diffusion method), it was found that the antimicrobial activity in NLP-ZMEO was higher than ZMEO against multidrug-resistant clinical pathogens that cause nosocomial infection. The subcytotoxic values of the tested NLP-ZMEO were higher than MICs and MBCs for MDR bacteria and chlorhexidine doses.

Antimicrobial efficacy of Nocardiopsis sp. MK_MSt033 against selected multidrug resistant clinical microbial pathogens

BackgroundActinomycetes show an active role in microbial disease control and antimicrobial metabolism production and were shown the greatest potentialities as sources of antimicrobial agents. The past few decades, an extensive literature has accumulated on the production of bioactive compounds from actinomycetes, particularily genus Streptomyces. MethodsThe actinomycetes were isolated with starch casein nitrate (SCN) agar medium. The prospective isolate was subjected to antimicrobial metabolites production. Further, the bio-extract was evaluated their biological properites by agar well diffusion assay and finally the extract was anaylized through GC–MS. ResultsIn the present study, isolated 9 actinomycetes and the isolates were examined for their antifungal activities. Of these nine isolates, the isolate MK_MSt033 picked out from the rest, hences, it showed significant control towards the selected microbial pathogens. The prospective strain MK_MSt033 was determined as Nocardiopsis sp. The strain displayed effective antimicrobial activities against both bacterial and fungal pathgoens such as Escherichia coli, Staphylococcus aureus, Pencillium sp., and Aspergillus flavus respectively. Subsequently the chemical nature of the compounds produced by the potential isolate MK_MSt033 and it was successfully determined by GC–MS and it were 18 compounds with different retention time. ConclusionThe identified isolate Nocardiopsis sp. MK_MSt033 exhibited potential antimicrobial activities against selected microbial pathogens. Thus, the soil inhabiting Nocardiopsis sp. has explored for pharmaceutically active compounds with promising medical applications.

Unravelling the antibiotic and heavy metal resistome of a chronically polluted soil.

The antibiotic and heavy metal resistome of a chronically polluted soil (3S) obtained from an automobile workshop in Ilorin, Kwara State, Nigeria was deciphered via functional annotation of putative ORFs (open reading frames). Functional annotation of antibiotic and heavy metal resistance genes in 3S metagenome was conducted using the Comprehensive Antibiotic Resistance Database (CARD), Antibiotic Resistance Gene-annotation (ARG-ANNOT) and Antibacterial Biocide and Metal Resistance Gene Database (BacMet). Annotation revealed detection of resistance genes for 15 antibiotic classes with the preponderance of beta lactamases, mobilized colistin resistance determinant (mcr), glycopepetide and tetracycline resistance genes, the OqxBgb and OqxA RND-type multidrug efflux pumps, among others. The dominance of resistance genes for antibiotics effective against members of the Enterobacteriaceae indicate possible contamination with faecal materials. Annotation of heavy metal resistance genes revealed diverse resistance genes responsible for the uptake, transport, detoxification, efflux and regulation of copper, zinc, cadmium, nickel, chromium, cobalt, mercury, arsenic, iron, molybdenum and several others. Majority of the antibiotic and heavy metal resistance genes detected in this study are borne on mobile genetic elements, which facilitate their spread and dissemination in the polluted soil. The presence of the heavy metal resistance genes is strongly believed to play a major role in the proliferation of antibiotic resistance genes. This study has established that soil is a huge repertoire of antibiotic and heavy metal resistome and due to the intricate link between human, animals and the soil environment, it may be a major contributor to the proliferation of multidrug-resistant clinical pathogens.

Effects of biotic and abiotic factors on biofilm growth dynamics and their heterogeneous response to antibiotic challenge

Over the last couple of decades, with the crisis of new antimicrobial arsenal, multidrug-resistant clinical pathogens have been observed extensively. In clinical and medical settings, these persistent pathogens predominantly grow as complex heterogeneous structures enmeshed in a self-produced exopolysaccharide matrix, termed as biofilms. Since biofilms can rapidly form by adapting new environmental surroundings and have potential effect on human health, it is critical to study them promptly and consistently. Biofilm infections are challenging in the contamination of medical devices and implantations, food processing and pharmaceutical industrial settings, and in dental area caries, periodontitis and so on. The persistence of infections associated with biofilms has been mainly attributed to the increased antibiotic resistance offered by the cells growing in biofilms. In fact, it is well known that this recalcitrance of bacterial biofilms is multifactorial, and there are several resistance mechanisms that may act in parallel in order to provide an enhanced level of resistance to the biofilm. In combination, distinct resistance mechanisms significantly decrease our ability to control and eradicate biofilm-associated infections with current antimicrobial arsenal. In addition, various factors are known to influence the process of biofilm formation, growth dynamics, and their heterogeneous response towards antibiotic therapy. The current review discusses the contribution of cellular and physiochemical factors on the growth dynamics of biofilm, especially their role in antibiotic resistance mechanisms of bacterial population living in surface attached growth mode. A systematic investigation on the effects and treatment of biofilms may pave the way for novel therapeutic strategies to prevent and treat biofilms in healthcare and industrial settings.

In Vitro Evaluation of Probiotic Potential and Safety Assessment of Lactobacillus mucosae Strains Isolated from Donkey's Lactation.

The study, for the first time, reports the efficacy, safety and probiotic properties of two Lactobacillus mucosae strains, Lact. mucosae SRV5 and Lact. mucosae SRV10 isolated from donkey milk. All major in vitro screening assays were employed to evaluate studied strains. Both strains displayed good survivability at gastric pH 2.0, 0.3% bile and simulated oro-gastrointestinal fluid (above 88%). Also, cultures demonstrated good cell surface hydrophobicity and auto-aggregation ability, clearly indicating their effective cell adhesion ability. Furthermore, functional attributes for both strains demonstrated their efficient bile salt hydrolase and cholesterol-reducing ability in spent broth. In addition to this, both strains expressed significant DPPH-radical scavenging ability of both culture supernatant and intact cells. Another auxiliary health benefit exhibited by both these strains is their antimicrobial potential against 18 enteric and 5 multidrug-resistant clinical pathogens with significant inhibition zone size. Extracellular enzyme production such as lipase, amylase, protease and esterase was also studied. Detailed safety evaluation study showed the presence of innate antibiotic resistance and absence of haemolysis, DNAse and gelatinase activity in both the strains. Also, none of the strains possessed toxic mucinolytic activity in mucin degradation assay. To conclude, both donkey milk isolates, Lact. mucosae SRV5[Accession number: MK990014] and Lact. mucosae SRV10 [Accession number: MN064860], exhibited excellent probiotic ability with tolerance to simulated oro-gastrointestinal fluids, cellular hydrophobicity, auto-aggregation, bile salt hydrolase, cholesterol reduction, high antioxidant activity and antimicrobial potential especially against multidrug-resistant pathogens.

In vitro Antibacterial Efficacy of Bryophyllum pinnatum Leaf Extracts

A study on the antibacterial activities of Bryophylum pinnatum against multidrug resistant bacterial pathogens was carried out in this research. Air-dried and powered Bryophylum pinnatum leaves was extracted using ethanol and aqueous solvents. Five bacteria strains including Staphylococcus aureus, Streptococcus pneumoniae, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa were obtained from the University of Benin Teaching Hospital and they were preliminarily identified using standard microbiological methods. Antibacterial activity was carried out using agar well diffusion method. Mean zone diameter of inhibition in aqueous extract ranged from 9.20±0.17-10.50±0.50mm and 9.30±0.33- 10.33±0.89mm against Escherichia coli and Staphylococcus aureus respectively at 25-100mg/ml. In the ethanol extract, mean zone of inhibition ranged from 9.50±0.28-13.33±0.88mm and 10.67±0.67-19.00±0.58mm at concentration range of 6.25-100mg/ml. Minimum inhibitory concentrations of ethanol extract ranged from 6.25-100 mg/ml against bacterial strains. While those of aqueous extract ranged from 25-100 mg/ml against bacterial isolates. Minimum bactericidal/fungicidal concentrations of ethanol extract ranged from 25-50 mg/ml. While in the aqueous extract, value was 50 mg/ml and against bacteria. The test bacterial pathogens were found to possess multiple drug resistance potential with multidrug resistance index ranging from 0.3 – 0.5. This study has shown that multidrug resistant clinical bacterial pathogens are sensitive to aqueous extract of Bryophyllum pinatum.

Bioactivity assessment of the Saudi Arabian Marine Streptomyces sp. Al-Dhabi-90, metabolic profiling and its in vitro inhibitory property against multidrug resistant and extended-spectrum beta-lactamase clinical bacterial pathogens

BackgroundMetabolites obtained from the marine microorganisms were known for their important role in microbial inhibition. Interestingly, bioprospecting of secondary metabolites from marine derived actinomycetes has huge demand especially in the treatment of multi drug resistant clinical pathogens. The present study subjected towards the identification of promising antimicrobial actinomycetes from the Arabian Gulf regions and metabolic profiling of the crude organic solvent extract by chromatographic techniques. MethodsThe strains were characterized by 16S rRNA sequencing. Extracellular metabolites were profiled by performing GC–MS analysis. MIC values of the compounds were detected using broth dilution technique. ResultsA Gram positive, spore forming filamentous Streptomyces sp. Al-Dhabi-90 possessed good antibacterial activities against the drug resistant pathogens were confirmed by 16S rRNA gene sequencing. Further, the gas chromatography coupled with mass spectrum analysis data revealed that the organic solvent extract of the fermented Streptomyces sp. Al-Dhabi-90 contained major components such as 3-methylpyridazine, n-hexadecanoic acid, indazol-4-one, octadecanoic acid and 3a-methyl-6-((4-methylphenyl) sul respectively. The Minimum Inhibitory Concentration (MIC) of the extract against Staphylococcus aureus and Klebsiella pneumoniae were 12.5 and 50μg/ml respectively. Against drug resistant ESBL pathogens such as Escherichia coli, Pseudomonsa aeroginosa and Proteus mirabilis were 12.5, and 25μg/ml respectively. Interestingly, the extract showed promising activity against the vancomycin resistant Enterococcus faecium at 50μg/ml. The increased level of cellular constituents after the extract treatment evidenced that the metabolites altered the membrane integrity of the pathogens. ConclusionConclusively, the marine Streptomyces sp. Al-Dhabi-90 is an ideal source for the treatment of multi drug resistant clinical pathogens.

Pretreatment with cathelicidin-BF ameliorates Pseudomonas aeruginosa pneumonia in mice by enhancing NETosis and the autophagy of recruited neutrophils and macrophages

Although the antimicrobial peptide cathelicidin-BF shows minimal cytotoxicity in mammalian cells and has excellent direct killing effects on multidrug-resistant clinical pathogens such as Pseudomonas aeruginosa, its clinical application is precluded by its high sensitivity to serum proteases. Here, we demonstrate that intravenous administration of cathelicidin-BF after P. aeruginosa infection did not increase the survival rate of mice with acute pneumonia but that pretreatment with cathelicidin-BF ameliorated pneumonia by effectively activating innate immunity. Enhanced neutrophil extracellular trap (NET) activation and release (NETosis) are key processes for capturing and killing bacteria, concomitantly enhanced macrophage clearance activity, including phagocytosis and autophagy, may eliminate NETs early enough to prevent severe tissue damage. Our study not only suggests a possible approach for applying cathelicidin-BF in vivo but also provides a possible defense strategy against multidrug-resistant pathogens, i.e., efficiently activation of innate immunity.

Antimicrobial Activity of a Bacteriocin Produced by Enterococcus faecalis KT11 against Some Pathogens and Antibiotic-Resistant Bacteria.

In this study, the antimicrobial activity of a bacteriocin produced by Enterococcus faecalis KT11, isolated from traditional Kargı Tulum cheese, was determined, and bacteriocin KT11 was partially characterized. The results showed that bacteriocin KT11 was antagonistically effective against various Gram-positive and Gram-negative test bacteria, including vancomycin- and/or methicillin-resistant bacteria. The activity of bacteriocin KT11 was completely abolished after treatment with proteolytic enzymes (proteinase K, α-chymotrypsin, protease and trypsin), which demonstrates the proteinaceous nature of this bacteriocin. Additionally, bacteriocin KT11 remained stable at pH values ranging from 2 to 11 and after autoclaving at 121℃ for 30 min. In addition, the activity of bacteriocin KT11 was stable after treatment with several surfactants (EDTA, SDS, Triton X-100, Tween 80 and urea) and organic solvents (chloroform, propanol, methanol, ethyl alcohol, acetone, hexane and ethyl ether). Cell-free supernatant of E. faecalis KT11 was subjected to ammonium sulfate precipitation and then desalted by using a 3.5-kDa cut-off dialysis membrane. The bacteriocin activity was determined to be 711 AU/mL in the dialysate. After tricine-SDS-PAGE analysis, one peptide band, which had a molecular weight of ~3.5 kDa, exhibited antimicrobial activity. Because the bacteriocin KT11, isolated from E. faecalis KT11, exhibits a broad antimicrobial spectrum, heat stability and stability over a wide pH range, this bacteriocin can be used as a potential bio-preservative in foods. Additionally, bacteriocin KT11 alone or in combination with conventional antibiotics may provide a therapeutic option for the treatment of multidrug-resistant clinical pathogens after further in vivo studies.

Characterization of Silver Nanomaterials Derived from Marine Streptomyces sp. Al-Dhabi-87 and Its In Vitro Application against Multidrug Resistant and Extended-Spectrum Beta-Lactamase Clinical Pathogens.

A novel antagonistic marine Streptomyces sp. Al-Dhabi-87 that was recovered from the Gulf region of Saudi Arabia was used to synthesize silver nanoparticles (NP) from the culture free extract. The produced NP were confirmed by UV-visible spectroscopy (UV-Vis), high-resolution scanning electron microscope (HRSEM), transmission electron microscope (TEM), Fourier-transform infrared spectroscopy (FTIR), Energy Dispersive Spectroscopy (EDAX), and X-ray Powder Diffraction (XRD), and broth micro dilution techniques were employed for the determination of minimum inhibitory concentrations (MIC) values. The synthesized NP was authenticated by alterations in color and wavelength scanning. HRSEM and TEM analysis confirmed that the size of the NP ranged from 10 to 17 nm and that it was spherical in shape. In addition, the FTIR spectrum revealed a variation in the band values from 500 to 3300 cm−1 respectively. Rietveld refinement analysis of the XRD data confirmed the size of the NP, which coincided with the results of the TEM analysis. In addition, the Riveted refinement analysis supported the TEM data. The NP documented significant activity against the wound infection microbial strains, such as Enterococcus faecalis, Staphylococcus epidermidis, and Staphylococcus aureus. Gram negative bacteria, such as Pseudomonas aeruginosa, Klebsiella pneumonia, and Escherichia coli revealed MIC values of 0.039, 0.078, and 0.152 mg/mL, respectively. The promising activity of NP towards extended-spectrum beta-lactamases E.coli, drug resistant Acinetobacter baumannii, and multidrug resistant S. aureus (at 0.018, 0.039, and 0.039 mg/mL, respectively) was advantageous. Overall, NP that were obtained from the novel Streptomyces sp. Al-Dhabi-87, with its promising antimicrobial activity towards the drug resistant pathogens, would be useful for healing infectious diseases.

Volatile Oils of Nepeta tenuifolia (Jing Jie) as an Alternative Medicine against Multidrug-Resistant Pathogenic Microbes.

Essential oils from the dried spikes of Nepeta tenuifolia (Benth) are obtained by steam distillation. Pulegone was identified as the main component in the spikes of N. tenuifolia through analysis, with greater than 85% purity obtained in this study. The essential oils are extremely active against all Gram-positive and some Gram-negative reference bacteria, particularly Salmonella enterica, Citrobacter freundii, and Escherichia coli. The minimum inhibitory concentration was found to be between 0.08 and 0.78% (against S. enterica), 0.39 and 0.78% (against C. freundii), and 0.097 and 0.39% (against E. coli), whereas the minimum bactericidal concentration varied in range from 0.097% to 1.04%. In general, the essential oils show a strong inhibitory action against all tested reference strains and clinical isolates. However, the antibacterial activity of EOs against both Pseudomonas aeruginosa reference strains and clinical isolates was relatively lower than other Gram-negative pathogens. The essential oils of N. tenuifolia also displayed bactericidal activities (MBC/MIC < 4) in this study. These findings reflect the bactericidal activity of the essential oils against a wide range of multidrug-resistant clinical pathogens in an in vitro study. In addition, we propose the fragmentation pathways of pulegone and its derivatives by LC-ESI-MS/MS in this study.

Making good use of the byproducts of cultivation: green synthesis and antibacterial effects of silver nanoparticles using the leaf extract of blueberry.

In this study, we made an effort to use blueberry leaves extract as a reducing and a capping agent to biosynthesize silver nanoparticles (AgNPs). The successful formation of AgNPs was confirmed with UV-visible spectroscopy, transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Furthermore, their antimicrobial activities against four kinds of multi drug resistant clinical pathogens and aquatic pathogens were investigated. The results showed that as-prepared AgNPs exhibited broad-spectrum antibacterial activities. The antibacterial effects of the AgNPs based on the structural damage and DNA degradation of the tested bacteria were also studied. The green synthesis of AgNPs using blueberry leaf extract, which provided a new idea on the use of the byproducts of blueberry harvesting.

ANTIMICROBIAL ACTIVITY AND TLC PROFILING OF CLERODENDRUM PHLOMIDIS LINN. F LEAF EXTRACT AGAINST MULTI-DRUG RESISTANT CLINICAL PATHOGENS

Objective: The aim of the present study is to evaluate the antibacterial and antifungal activities of different solvent extracts of leaves of Clerodendrum phlomidis against multi-drug resistant clinical pathogens and to perform Thin Layer Chromatography (TLC) profiling of the extracts.Methods: The leaf powder was sequentially extracted with petroleum ether, ethyl acetate, acetone, and methanol. The extracts were tested for their antimicrobial activity against 20 bacterial strains and 15 fungal strains which were multiple drugs resistant by disc diffusion method. TLC profiling of all four extracts was performed.Results: The petroleum ether and ethyl acetate extracts showed antimicrobial activity against four bacteria and seven fungal strains. The highest zone of inhibition (18±0.50 mm) for bacteria was recorded against Staphylococcus epidermis by ethyl acetate extract and for fungi, the petroleum ether extract showed 13±0.00 mm against Trichophyton rubrum. TLC profiles showed that ethyl acetate extract possessed more compounds.Conclusion: From the results of the present study it is concluded that the petroleum ether and ethyl acetate extracts of C. phlomidis leaves are good sources of antimicrobial compounds which can inhibit multiple drug resistant pathogens.

In Vitro Activities of Nisin and Nisin Derivatives Alone and In Combination with Antibiotics against Staphylococcus Biofilms.

The development and spread of pathogenic bacteria that are resistant to the existing catalog of antibiotics is a major public health threat. Biofilms are complex, sessile communities of bacteria embedded in an organic polymer matrix which serve to further enhance antimicrobial resistance. Consequently, novel compounds and innovative methods are urgently required to arrest the proliferation of drug-resistant infections in both nosocomial and community environments. Accordingly, it has been suggested that antimicrobial peptides could be used as novel natural inhibitors that can be used in formulations with synergistically acting antibiotics. Nisin is a member of the lantibiotic family of antimicrobial peptides that exhibit potent antibacterial activity against many Gram-positive bacteria. Recently we have used bioengineering strategies to enhance the activity of nisin against several high profile targets, including multi-drug resistant clinical pathogens such as methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, staphylococci, and streptococci associated with bovine mastitis. We have also identified nisin derivatives with an enhanced ability to impair biofilm formation and to reduce the density of established biofilms of methicillin resistant S. pseudintermedius. The present study was aimed at evaluating the potential of nisin and nisin derivatives to increase the efficacy of conventional antibiotics and to assess the possibility of killing and/or eradicating biofilm-associated cells of a variety of staphylococcal targets. Growth curve-based comparisons established that combinations of derivatives nisin V + penicillin or nisin I4V + chloramphenicol had an enhanced inhibitory effect against S. aureus SA113 and S. pseudintermedius DSM21284, respectively, compared to the equivalent nisin A + antibiotic combinations or when each antimicrobial was administered alone. Furthermore, the metabolic activity of established biofilms treated with nisin V + chloramphenicol and nisin I4V + chloramphenicol combinations revealed a significant decrease in S. aureus SA113 and S. pseudintermedius DSM21284 biofilm viability, respectively, compared to the nisin A + antibiotic combinations as determined by the rapid colorimetric XTT assay. The results indicate that the activities of the nisin derivative and antibiotic combinations represent a significant improvement over that of the wild-type nisin and antibiotic combination and merit further investigation with a view to their use as anti-biofilm agents.

An 11,000 Isolate Same Plate/Same Day Comparison Reveals Notable Differences Among the Three Most Widely Used Platforms for Analyzing Multidrug-Resistant Clinical Pathogens

An 11,000 Isolate Same Plate/Same Day Comparison Reveals Notable Differences Among the Three Most Widely Used Platforms for Analyzing Multidrug-Resistant Clinical Pathogens

Susceptibility of multidrug resistant clinical pathogens to a chlorhexidine formulation.

Multidrug resistant pathogens are a widespread problem in the hospital setting especially on intensive care units (ICU). This study evaluated the susceptibility of clinical isolates of gramnegative extensively drug resistant organisms (XDR), methicillinresistant Staphylococcus aureus (MRSA), and vancomycin-resistant Enterococcus (VRE) to a proprietary chlorhexidine digluconate (CHG) formulation used in one brand of CHG-impregnated cloths. Ten isolates each of XDR Pseudomonas aeruginosa, XDR Acinetobacter baumannii, XDR Klebsiella pneumoniae, XDR Escherichia coli, MRSA, and vancomycin-resistant Enterococcus faecium from our hospital were tested. All isolates were susceptible to the proprietary CHG formulation (0.5%, 1%, 2%), with 99% to 100% suppression of growth at the earliest time point in time kill assays (1 minute for gram-positive and 15 seconds for gram-negative organisms). Minimum inhibitory concentrations ranged from 1 : 4096 to 1 : 65536 for MRSA, 1 : 1024 to 1 : 2048 for VRE, 1 : 2048 to 1 : 4096 for XDR E. coli, 1 : 512 to 1 : 2048 for XDR A. baumannii, 1 : 512 to 1 : 1024 for XDR P. aeruginosa, and 1 : 512 to 1 : 1024 for XDR K. pneumoniae. Cloths impregnated with this CHG formulation provide effective protection against colonization and infection by many pathogens. This study provides in vitro evidence that the proprietary CHG formulation used in one brand of CHG-impregnated cloths is effective against XDR gram-negative organisms, MRSA, and VRE.