scholarly journals Sequential Hypertonic-Hypotonic Treatment Enhances Efficacy of Antibiotic against Acinetobacter baumannii Biofilm Communities

Antibiotics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 832
Author(s):  
Azeza Falghoush ◽  
Haluk Beyenal ◽  
Douglas R. Call
Keyword(s):  
Acinetobacter Baumannii ◽  
Deionized Water ◽  
Bacterial Biofilm ◽  
Broth Culture ◽  
Log P ◽  
Single Treatment ◽  
Cell Counts ◽  
Viable Cells ◽  
Hypotonic Treatment ◽  
Antibiotic Efficacy

Infections with bacterial biofilm communities are highly tolerant of antibiotics. This protection is attributed, in part, to a hydrated extracellular polymeric substance (EPS) that surrounds the bacterial community and that limits antibiotic diffusion. In this study, we evaluated whether it is possible to dehydrate and then re-hydrate a biofilm as a means to increase antibiotic penetration and efficacy. Acinetobacter baumannii biofilms (24 h) were exposed to hypertonic concentrations of maltodextrin, sucrose or polyethylene glycol (PEG) as the dehydration step. These biofilms were then washed with deionized water containing 10 times the concentration of antibiotics needed to kill these bacteria in broth culture (50 µg/mL tobramycin, 300 µg/mL chloramphenicol, 20 µg/mL ciprofloxacin or 100 µg/mL erythromycin) as the rehydration step. Biofilms were then harvested, and the number of viable cells was determined. Sequential treatment with PEG and tobramycin reduced cell counts 4 to 7 log (p < 0.05) relative to combining PEG and tobramycin in a single treatment, and 3 to 7 log relative to tobramycin treatment alone (p < 0.05). Results were variable for other osmotic compounds and antibiotics depending on the concentrations used, likely related to mass and hydrophobicity. Our findings support future clinical evaluation of sequential regimens of hypertonic and hypotonic solutions to enhance antibiotic efficacy against chronic biofilm infections.

Bifunctional Composites for Biofilms Modulation on Cervical Restorations

2021 ◽  
pp. 002203452110181
Author(s):  
A.A. Balhaddad ◽  
I.M. Garcia ◽  
L. Mokeem ◽  
M.S. Ibrahim ◽  
F.M. Collares ◽  
...  
Keyword(s):  
Free Energy ◽  
Surface Free Energy ◽  
Contact Angles ◽  
Bacterial Biofilm ◽  
Dental Composite ◽  
Log P ◽  
Rrna Gene ◽  
Cervical Lesions ◽  
Biofilm Growth ◽  
Biofilm Development

Cervical composites treating root carious and noncarious cervical lesions usually extend subgingivally. The subgingival margins of composites present poor plaque control, enhanced biofilm accumulation, and cause gingival irritation. A potential material to restore such lesions should combine agents that interfere with bacterial biofilm development and respond to acidic conditions. Here, we explore the use of new bioresponsive bifunctional dental composites against mature microcosm biofilms derived from subgingival plaque samples. The designed formulations contain 2 bioactive agents: dimethylaminohexadecyl methacrylate (DMAHDM) at 3 to 5 wt.% and 20 wt.% nanosized amorphous calcium phosphate (NACP) in a base resin. Composites with no DMAHDM and NACP were used as controls. The newly formulated 5% DMAHDM–20% NACP composite was analyzed by micro-Raman spectroscopy and transmission electron microscopy. The wettability and surface-free energy were also assessed. The inhibitory effect on the in vitro biofilm growth and the 16S rRNA gene sequencing of survival bacterial colonies derived from the composites were analyzed. Whole-biofilm metabolic activity, polysaccharide production, and live/dead images of the biofilm grown over the composites complement the microbiological assays. Overall, the designed formulations had higher contact angles with water and lower surface-free energy compared to the commercial control. The DMAHDM-NACP composites significantly inhibited the growth of total microorganisms, Porphyromonas gingivalis, Prevotella intermedia/nigrescens, Aggregatibacter actinomycetemcomitans, and Fusobacterium nucleatum by 3 to 5-log ( P < 0.001). For the colony isolates from control composites, the composition was typically dominated by the genera Veillonella, Fusobacterium, Streptococcus, Eikenella, and Leptotrichia, while Fusobacterium and Veillonella dominated the 5% DMAHDM–20% NACP composites. The DMAHDM-NACP composites contributed to over 80% of reduction in metabolic and polysaccharide activity. The suppression effect on plaque biofilms suggested that DMAHDM-NACP composites might be used as a bioactive material for cervical restorations. These results may propose an exciting path to prevent biofilm growth and improve dental composite restorations’ life span.

Long-Term Storage Stability of the Bacteriocin Propionicin PLG-1 Produced by Propionibacterium thoenii and Potential as a Food Preservative†

1996 ◽  
Vol 59 (5) ◽  
pp. 481-486 ◽  
Author(s):  
HSING-YI HSIEH ◽  
BONITA A. GLATZ
Keyword(s):  
Storage Stability ◽  
Skim Milk ◽  
Lactobacillus Delbrueckii ◽  
Food Preservative ◽  
Long Term Storage ◽  
Cell Counts ◽  
Viable Cells ◽  
Propionibacterium Thoenii ◽  
Term Storage

Propionicin PLG-1, a bacteriocin produced by Propionibacterium thoenii strain P127, was tested for characteristics that could determine its usefulness as a food preservative: long-term storage stability and effectiveness in a food model system. Partially purified propionicin PLG-1 samples, lyophilized and nonlyophilized, were stored at 25, 4, and −20°C. Bacteriocin activity increased by as much as 200% over the first 10 days of storage in nonlyophilized samples stored at 25 or 4°C. Activity then decreased gradually for samples stored at 25°C while samples stored at 4°C retained high activity through 14 weeks of storage. Nonlyophilized samples frozen at −20°C and lyophilized samples stored at all temperatures did not change significantly in activity through 25 weeks of storage. Propionicin was added at 100 and 1,000 arbitrary units (AU)/ml to lactobacilli MRS broth and to skim milk, each inoculated with 105 cells per ml of Lactobacillus delbrueckii ATCC 4797. Upon incubation at 37°C with 1,000 AU/ml, cell numbers were reduced by at least 4 log units within 2 h and no viable cells were detected after 96 h in either medium. With 100 AU/ml of propionicin, viable cells were reduced by 2 log units within 12 h at 37°C, but culture growth resumed after 24 h. At 15°C, no viable cells were detected after 48 h in the presence of 1,000 AU/ml of propionicin, while viable cell counts were gradually reduced to about 10 cells per ml by 168 h in the presence of 100 AU/ml of propionicin.

scholarly journals Pimenta Oil as a Potential Treatment for Acinetobacter baumannii Wound Infection: In Vitro and In Vivo Bioassays in Relation to Its Chemical Composition

Antibiotics ◽  
2020 ◽  
Vol 9 (10) ◽  
pp. 679
Author(s):  
Maha M. Ismail ◽  
Reham Samir ◽  
Fatema R. Saber ◽  
Shaimaa R. Ahmed ◽  
Mohamed A. Farag
Keyword(s):  
Chemical Composition ◽  
Wound Infection ◽  
Acinetobacter Baumannii ◽  
Bacterial Biofilm ◽  
Mass Spectrometry Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Infection Model ◽  
Bacterial Strains ◽  
Mice Model ◽  
Pimenta Dioica

Bacterial biofilm contributes to antibiotic resistance. Developing antibiofilm agents, more favored from natural origin, is a potential method for treatment of highly virulent multidrug resistant (MDR) bacterial strains; The potential of Pimenta dioica and Pimenta racemosa essential oils (E.Os) antibacterial and antibiofilm activities in relation to their chemical composition, in addition to their ability to treat Acinetobacter baumannii wound infection in mice model were investigated; P. dioica leaf E.O at 0.05 µg·mL−1 efficiently inhibited and eradicated biofilm formed by A. baumannii by 85% and 34%, respectively. Both P. diocia and P. racemosa leaf E.Os showed a bactericidal action against A. baumanii within 6h at 2.08 µg·mL−1. In addition, a significant reduction of A. baumannii microbial load in mice wound infection model was found. Furthermore, gas chromatography mass spectrometry analysis revealed qualitative and quantitative differences among P. racemosa and P. dioica leaf and berry E.Os. Monoterpene hydrocarbons, oxygenated monoterpenes, and phenolics were the major detected classes. β-Myrcene, limonene, 1,8-cineole, and eugenol were the most abundant volatiles. While, sesquiterpenes were found as minor components in Pimenta berries E.O; Our finding suggests the potential antimicrobial activity of Pimenta leaf E.O against MDR A. baumannii wound infections and their underlying mechanism and to be further tested clinically as treatment for MDR A. baumannii infections.

A Standardized Model of Experimental Furunculosis in Rainbow Trout (Salmo gairdneri)

1980 ◽  
Vol 37 (4) ◽  
pp. 746-750 ◽  
Author(s):  
C. Michel
Keyword(s):  
Rainbow Trout ◽  
Intramuscular Injection ◽  
Infected Fish ◽  
Aeromonas Salmonicida ◽  
Salmo Gairdneri ◽  
Exponential Growth Phase ◽  
Cell Counts ◽  
Viable Cells ◽  
Treated Fish ◽  
Drop Plate

With the aid of published information, we have developed a standardized and reproducible experimental model of furunculosis in rainbow trout (Salmo gairdneri). The infective doses (LD50 = 200 to 2000 germs, i.m.) employed strains of Aeromonas salmonicida, the virulence of which was maintained by passage in 15-g fingerlings. The number of viable cells in the dose was conveniently determined using the drop-plate enumeration technique; however, meaningful cell counts could only be obtained if broth cultures used for infecting the fish were harvested early in the exponential growth phase (OD < 1.000 at 525 nm). Better results were obtained with intramuscular injection than with intraperitoneal injection. The infection procedure involved injecting a dose of 10 LD50, intramuscularly, into each of 30 fish held at 15 °C and recording the mortalities for 10 d. Protection tests in which Tribrissen (28 mg sulfadiazine and 5.6 mg trimethoprim/kg fish for 8 d) was fed or tetracycline (1 mg per fish) i.m. injected into the infected fish served to demonstrate the value of the model. Results were in agreement with field observations with no death for treated fish and a mortality of 96%, for untreated fish. Key wordss rainbow trout, Salmo gairdneri; Aeromonas salmonicida, furunculosis, experimental infection

scholarly journals Perbedaan daya antiglukan NaOCl 2,5% dan ekstrak kulit manggis (Garcinia mangostana L.) 0,09% terhadap Enterococcus faecalis (Comparison of antiglucan activity between NaOCl 2.5% and mangosteen pericarp extract (Garcinia mangostana Linn) 0.09% against Enterococcus faecalis)

2019 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Nabiela Rahardia ◽  
M Rulianto ◽  
Dian Agustin Wahjuningrum
Keyword(s):  
Enterococcus Faecalis ◽  
Root Canal ◽  
Bacterial Biofilm ◽  
Control Group ◽  
Garcinia Mangostana ◽  
Control Group Design ◽  
Root Canals ◽  
Viable Cells ◽  
Experimental Laboratory ◽  
The Difference

Background. Failure of endodontic treatment is commonly caused by the persistent microorganisms remaining in the root canal such as Enterococcus faecalis. Enterococcus faecalis can form a biofilm in tough environmental conditions within the root canals and caused biofilm-mediated infections which needs more complicated treatment due to the increasing of antimicrobial resistance. The biofilm formation initial and most important step is bacteria adherence to the solid surface that is mediated by glucan. NaOCl 2.5% is a commonly used root canal medicaments but can cause injury of periapical tissue. Mangosteen pericarp extract contains flavonoid, tannin, and xanthone have mechanism for inhibiting adherence of bacterial biofilm. Difference of antibacterial activity between NaOCl 2.5% and mangosteen pericarp extract 0.09% can be determined by experimental laboratory to determine the adherence of bacteria in each treatment. Purpose. The aim of this study was to assess the difference of antiglucan activity between NaOCl 2.5% and mangosteen pericarp extract 0.09% on Enterococcus faecalis. Method. This study was designed as an experimental laboratory study with post  test only control group design using Enterococcus faecalis ATCC 29212. Mangosteen pericarp was extracted using maceration method. Adherence analysis was observed after 24 hours by examining the viable cells in suspension. These viable cells are measured by UV-Vis spectrophotometer to compare the suspensions’ turbidity. Using the Independent T-Test, significantly less bacteria were found adhering to the mangosteen pericarp extract. Results. Absorbancy difference level by mangosteen pericarp extract 0.09% is significantly greater than the NaOCl 2.5% (p<0.05). Conclusion. Antiglucan activity that generated by mangosteen pericarp extract 0.09% is greater than NaOCl 2.5%

scholarly journals Caspofungin and Polymyxin B Reduce the Cell Viability and Total Biomass of Mixed Biofilms of Carbapenem-Resistant Pseudomonas aeruginosa and Candida spp.

2020 ◽  
Vol 11 ◽  
Author(s):  
Luciana Fernandes ◽  
Bruna Nakanishi Fortes ◽  
Nilton Lincopan ◽  
Kelly Ishida
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Inhibitory Activity ◽  
Inhibitory Concentration ◽  
Polymyxin B ◽  
Antibiofilm Activity ◽  
Total Biomass ◽  
Planktonic Cells ◽  
Carbapenem Resistant ◽  
Cell Counts ◽  
Viable Cells

Pseudomonas aeruginosa and Candida spp. are biofilm-forming pathogens commonly found colonizing medical devices, being mainly associated with pneumonia and bloodstream infections. The coinfection by these pathogens presents higher mortality rates when compared to those caused by a single microbial species. This study aimed to evaluate the antibiofilm activity of echinocandins and polymyxin B (PMB) against polymicrobial biofilms of carbapenem-resistant (CR) Pseudomonas aeruginosa and Candida spp. (C. albicans, C. parapsilosis, C. tropicalis, and C. glabrata). In addition, we tested the antimicrobial effect on their planktonic and monomicrobial biofilm counterparties. Interestingly, beyond inhibition of planktonic [minimum inhibitory concentration (MIC) = 0.5 μg/ml] and biofilm [minimum biofilm inhibitory concentration (MBIC)50 ≤ 2–8 μg/ml] growth of P. aeruginosa, PMB was also effective against planktonic cells of C. tropicalis (MIC = 2 μg/ml), and polymicrobial biofilms of CR P. aeruginosa with C. tropicalis (MBIC50 ≤ 2 μg/ml), C. parapsilosis (MBIC50 = 4–16 μg/ml), C. glabrata (MBIC50 = 8–16 μg/ml), or C. albicans (MBIC50 = 8–64 μg/ml). On the other hand, while micafungin (MFG) showed highest inhibitory activity against planktonic (MIC ≤ 0.008–0.5 μg/ml) and biofilm (MBIC50 ≤ 2–16 μg/ml) growth of Candida spp.; caspofungin (CAS) displays inhibitory activity against planktonic cells (MIC = 0.03–0.25 μg/ml) and monomicrobial biofilms (MBIC50 ≤ 2–64 μg/ml) of Candida spp., and notably on planktonic and monomicrobial biofilms of CR P. aeruginosa (MIC or MBIC50 ≥ 64 μg/ml). Particularly, for mixed biofilms, while CAS reduced significantly viable cell counts of CR P. aeruginosa and Candida spp. at ≥32 and ≥ 2 μg/ml, respectively; PMB was effective in reducing viable cells of CR P. aeruginosa at ≥2 μg/ml and Candida spp. at ≥8 μg/ml. Similar reduction of viable cells was observed for CAS (32–64 μg/ml) combined with PMB (2 μg/ml). These findings highlight the potential of PMB and CAS for the treatment of polymicrobial infections caused by Candida spp. and critical priority CR P. aeruginosa.

Gold nanoclusters augment a fluoroquinolone lethality against biofilm associated persister cells

2020 ◽  
Author(s):  
Laurent Bekale ◽  
Peter L. Santa Maria ◽  
Zhixin Cao ◽  
Xiaohua Chen ◽  
Anping Xia ◽  
...  
Keyword(s):  
Paradigm Shift ◽  
Gold Nanoclusters ◽  
Bacterial Biofilm ◽  
Bacterial Burden ◽  
Chronic Infections ◽  
Persister Cells ◽  
Gold Nanocluster ◽  
Suppurative Otitis Media ◽  
Fold Reduction ◽  
Antibiotic Efficacy

Abstract Persister cells are an important medical concern, leading to the overuse of antibiotics and ultimately contributing to antimicrobial resistance. The use of an adjuvant that augments the antibiotic efficacy has yet to be explored for combating persister cells within biofilm infections. Here we demonstrate a paradigm shift in targeting bacteria in chronic infections by coadministration of a conventional antibiotic with a novel engineered gold nanocluster (AuNC@CPP). AuNC@CPP was found to reduce the minimum biofilm eradication concentration (MBEC) of ofloxacin up to 300-fold (from > 3000 μg/mL to 10 μg/mL). Compared to ofloxacin alone (FLOXIN®Otic), coadministration of ofloxacin with AuNC@CPP induces up to a 10,000-fold reduction in bacterial burden in a validated mouse model of chronic P. aeruginosa of ear infection mimicking chronic suppurative otitis media. The biocompatibility of AuNC@CPP encourages efforts for development as an antibiotic adjunct for combating bacterial biofilm infections.

Effects of Steroid Treatment on Childhood ALL Stem Cells.

Blood ◽  
2007 ◽  
Vol 110 (11) ◽  
pp. 3462-3462
Author(s):  
Charlotte V. Cox ◽  
Paraskevi Diamanti ◽  
Pamela R. Kearns ◽  
Allison Blair
Keyword(s):  
Stem Cells ◽  
Annexin V ◽  
Absolute Number ◽  
Proliferative Potential ◽  
Disease Relapse ◽  
Childhood All ◽  
Cell Counts ◽  
Viable Cells ◽  
Significant Difference ◽  
The Absolute

Abstract Several lines of evidence indicate a central role for stem cells in the pathogenesis of human leukaemias and exemplify the need to develop strategies that target this sub-population of cells. It is proposed that these cells may exhibit different chemo-sensitivity and consequently may be resistant to drug regimens designed to kill the bulk leukaemia population. Inherently resistant leukaemia stem cells may contribute to subsequent disease relapse. Clearly, there is a need to assess the relative efficacy of therapeutic agents on the sub-populations of cells in addition to the bulk leukaemia. We have previously demonstrated that the sub-population of childhood acute lymphoblastic leukaemia (ALL) cells, capable of serially engrafting NOD/SCID mice, have a CD34+/CD19− or CD34+/CD7− phenotype in B cell precursor (BCP) ALL and T-ALL, respectively. In this investigation we have compared the efficacy of a current glucocorticoid therapeutic agent on these putative ALL stem cells with their effects on the bulk leukaemia population. The effect of dexamethasone (dex), a key component of the treatment of childhood ALL, on primary ALL cells from 13 paediatric cases was examined. Unsorted ALL cells were co-cultured with and without dex for 48 hours. Subsequently, cell viability and apoptosis were evaluated by flow cytometry using propidium iodide and annexin V staining, with Flow-Count fluorospheres to directly determine absolute cell counts. Primary cells from 11 patients with BCP ALL were sorted for expression of CD34/CD19 and cells from 2 T-ALL cases were sorted for expression of CD34/CD7. The unsorted cells and the sorted sub-fractions were co-cultured with increasing concentrations of dex (0.05 to 500 μM) to compare the relative chemosensitivity of the bulk and putative leukaemia stem cell populations. The unsorted leukaemia populations were completely refractory to dex with no significant difference in the levels of apoptosis observed or the absolute number of viable cells in the treated samples and in the untreated controls. Interestingly, when the sorted populations were assessed, an increase in the absolute numbers of viable CD34+/CD19− (1.2–9.7 fold, P<0.02) and CD34+/CD7− (2.6–5 fold, P<0.04) leukaemia cells were observed even at the highest steroid dose, compared to the respective untreated sub-fractions. The other leukaemic sub-fractions did not show a significant increase in the number of viable cells following dex exposure. These data show that 10 out of 11 drug treated primary leukaemia cells were resistant to dex. The putative CD34+/CD19− BCP ALL cells and CD34+/CD7− T-ALL cells showed a significantly enhanced proliferative potential when exposed to the drug, suggesting that it is these cells that may be responsible for disease relapse.

Identification of novel 1, 3-oxazole and imidazole-5-one that inhibits bacterial biofilm formation of Acinetobacter baumannii

Gene Reports ◽  
2020 ◽  
Vol 20 ◽  
pp. 100782
Author(s):  
Mohammed F. AL Marjani ◽  
Fatima S. Ali ◽  
Sawsan H. Authman ◽  
Israa M.S. AL Kadmy ◽  
Roaa M. Abdul Amir
Keyword(s):  
Acinetobacter Baumannii ◽  
Biofilm Formation ◽  
Bacterial Biofilm

Enumeration of viable Escherichia coli by real-time PCR with propidium monoazide

2012 ◽  
Vol 66 (10) ◽  
pp. 2065-2073 ◽  
Author(s):  
N. Yokomachi ◽  
J. Yaguchi
Keyword(s):  
Escherichia Coli ◽  
Wastewater Treatment ◽  
Real Time ◽  
Real Time Pcr ◽  
Wastewater Treatment Plants ◽  
Propidium Monoazide ◽  
E Coli ◽  
Cell Counts ◽  
Viable Cells ◽  
Heat Treated

A photo-inducible DNA-binding dye, propidium monoazide (PMA), was used to distinguish viable and dead Escherichia coli cells. Microscopic observations using a combination of the dyes 4′,6-diamidino-2-phenylindole and PMA indicated that PMA stained only dead cells, with membrane damage, red. Mixtures of viable and heat-treated E. coli cells were subjected to real-time polymerase chain reaction (PCR) with PMA treatment. Viable cell counts were linearly related to real-time PCR threshold cycle values for PMA-treated cells in the mixtures of viable and heat-treated cells, as long as the ratio of dead cells to viable cells was no greater than 10. In the wastewater treatment plants, total, viable and culturable E. coli were enumerated by real-time PCR, real-time PCR coupled with PMA treatment and the most probable number method using EC-MUG medium, respectively. The concentrations of viable E. coli in the wastewater treatment plants were much higher than those of culturable cells. In addition, viable cells were even more chlorine resistant than culturable ones.

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