Reduction In Bacteria Counts Research Articles

Application of Lytic Bacteriophages and Their Enzymes to Reduce Saprophytic Bacteria Isolated from Minimally Processed Plant-Based Food Products-In Vitro Studies.

The aim of this study was to isolate phage enzymes and apply them in vitro for eradication of the dominant saprophytic bacteria isolated from minimally processed food. Four bacteriophages-two Enterobacter-specific and two Serratia-specific, which produce lytic enzymes-were used in this research. Two methods of phage enzyme isolation were tested, namely precipitation with acetone and ultracentrifugation. It was found that the number of virions could be increased almost 100 times due to the extension of the cultivation time (72 h). The amplification of phage particles and lytic proteins was dependent on the time of cultivation. Considering the influence of isolated enzymes on the growth kinetics of bacterial hosts, proteins isolated with acetone after 72-hour phage propagation exhibited the highest inhibitory effect. The reduction of bacteria count was dependent on the concentration of enzymes in the lysates. The obtained results indicate that phages and their lytic enzymes could be used in further research aiming at the improvement of microbiological quality and safety of minimally processed food products.

Exploring the Physicochemical, Mechanical, and Photocatalytic Antibacterial Properties of a Methacrylate-Based Dental Material Loaded with ZnO Nanoparticles.

While resin-based materials meet the many requirements of a restorative material, they lack adequate, long-lasting antimicrobial power. This study investigated a zinc oxide nanoparticle (ZnO NP)-loaded resin-blend (RB) toward a new antimicrobial photodynamic therapy (aPDT)-based approach for managing dental caries. The results confirmed that up to 20 wt% ZnO NPs could be added without compromising the degree of conversion (DC) of the original blend. The DC achieved for the 20 wt% ZnO NP blend has been the highest reported. The effects on flexural strength (FS), shear bond strength to dentin (SBS), water sorption (WS), solubility (SL), and viability of Streptococcus mutans under 1.35 J/cm2 blue light or dark conditions were limited to ≤20 wt% ZnO NP loading. The addition of up to 20 wt% ZnO NPs had a minimal impact on FS or SBS, while a reduction in the bacteria count was observed. The maximum loading resulted in an increase in SL. Furthermore, 28-day aging in 37 °C water increased the FS for all groups, while it sustained the reduction in bacteria count for the 20 wt% resin blends. Overall, the ZnO NP-loaded resin-based restorative material presents significant potential for use in aPDT.

Superwetting antibacterial copper oxide nanoflake foil substrates generated by thermal oxidation

A facile one-step method of roughened copper foils of 0.0076 ​mm thickness heated on the open flame for 15 ​s produced superhydrophilic surfaces that exhibited superwetting at average radial growths of 10.8 ​mm/s following drop dispensation. Superhydrophilicity was found to deteriorate over time and XRD analysis ruled out compositional change as the cause of this behaviour. Instead, SEM imaging revealed wrinkled 20–30 ​nm-thick nanoflakes that were predominantly stretched out initially to engender superwetting properties via Wenzel wetting. These extended microstructures folded up with time due to relaxation of the residual stresses from the thermal oxidation process, resulting in temporal reduction in superhydrophilicity, which can be restored by reapplying thermal oxidation. The impingement of air with 80 psi pressure on the substrate also caused similar deterioration. The superwetting characteristic also endowed these substrates with anti-bacterial properties where a 56% reduction in bacteria count with Staphylococcus epidermidis was found. • Copper oxide substrates was created by facile one-step thermal oxidation of 0.0076 ​mm thick copper foils in 15 ​s. • The substrate has zero contact angle and spreads at average radial growths of 10.8 ​mm/s following drop dispensation. • Superwetting was promoted by wrinkled 20–30 ​nm-thick nanoflakes that were predominantly stretched out. • Superhydrophilicity deterioration over time in room conditions could be restored by reheating the substrate. • A 56% reduction in Staphylococcus epidermidis count was found due to superwetting and anti-bacterial characteristics.

In-vitro evaluation of antimicrobial efficacy of triple antibiotic paste, metapex and newly introduced iodine based asphaline temp as intracanal medicament against enterococcus faecalis

Background: Microorganisms and their products are considered as the etiological agents of pulp necrosis and peri-radicular lesions. They may survive during endodontic procedures due to anatomical structural complexities and limitations of access by instrumentation and irrigants. The present study was conducted to assess antimicrobial efficacy of newly introduced iodine based Asphaline Temp, Triple antibiotic paste and Calcium hydroxide based Metapex against Enterococcus faecalis. Materials & Methods: 90 extracted, single-rooted human permanent teeth were instrumented and autoclaved. Samples were inoculated with the pure culture of E. faecalis and incubated. After incubation, colony-forming units (CFUs) were recorded before medication. Each group was further divided into 3 subgroups based on time duration of testing for days – 1 day, 5 days, and 7 days, containing 10 samples each. Group I – Asphaline Temp; Group II – Triple antibiotic paste (TAP); Group III – Metapex. The various time interval bacterial CFUs within the group were compared. Results: Percentage reduction in bacteria count on 1 day, 5 day and 7 day in Group I (Asphaline Temp) was 77.2, 96.5 and 98.3; in Group II (TAP) was 70.5, 90.4 and 93.2 and in Group III (Metapex ) was 25.8, 46.2 and 58.2.

Highly Bactericidal Macroporous Antimicrobial Polymeric Gel for Point-of-Use Water Disinfection

Access to clean and safe water supply remains inadequate in many developing countries. One of the key challenges is to remove pathogenic bacteria from the water supply via effective water disinfection technologies to prevent the spread of diseases and to ensure the safety of consumers. Herein, a highly effective point-of-use (on-demand) water disinfection technology, in the form of a polymeric scaffold called macroporous antimicrobial polymeric gel (MAPG), is demonstrated. MAPG is easy to fabricate, completely organic and possess inherent antimicrobial property which makes it non-reliant on inorganic compounds such as silver where the long-term toxicity remains unknown. MAPG is highly bactericidal and can disinfect bacteria-contaminated water (ca. 108 CFU mL−1) at a capacity of about >50 times the mass of the organic material used, inactivating >99% of both Gram-negative and Gram-positive bacteria including Escherichia coli, Vibrio cholerae and Staphylococcus aureus within 20 minutes of treatment. When fabricated in a syringe, MAPG eliminates E. coli from contaminated water source by >8.0 log10 reduction in bacteria counts (i.e., no viable bacteria were detected after treatment), and the syringe can be reused multiple times without losing potency. The MAPG technology is not only restricted to water disinfection but may also be applicable in other bacteria inactivation applications.

Low-Frequency Ultrasound Enhances Antimicrobial Activity of Colistin–Vancomycin Combination against Pan-Resistant Biofilm of Acinetobacter baumannii

Acinetobacter baumannii biofilms in catheters are very difficult to treat. Low-frequency ultrasound (LFU) may improve bactericidal or bacteriostatic activity. However, no previous studies have been reported on its efficacy against pan-resistant biofilms of A. baumannii. This study was designed to investigate whether LFU can enhance the activity of colistin, vancomycin and colistin–vancomycin combinations against pan-resistant biofilms of A. baumannii. The efficacy of colistin combinations was determined using the fractional inhibitory concentration index (FICI). The antibacterial effect was determined from bacteria counts in biofilms and the establishment of 24-h time-kill curves. A significantly synergistic effect was detected between colistin and vancomycin (FICI <0.05). We found that although application of LFU (40 kHz, 600 mW/cm2, 30 min, duty cycle 1:9) alone or in combination with a single agent failed to significantly reduce bacteria counts in biofilms, it apparently enhanced the antibacterial effectiveness of combinations of these agents. Moreover, higher concentrations of colistin in the combination treatments resulted in a better ultrasound-enhanced antibacterial effect. In 24-h time-kill curves, the combination of colistin (8 μg/mL) plus vancomycin (4 μg/mL) with LFU caused a significant reduction in bacteria counts in biofilms after 8 h and a continuing decline until 24 h. Bacterial counts were reduced by 3.77 log(CFU/mL) by LFU plus combinations, compared with combinations without LFU at 24 h. Our results indicate that LFU in combination with colistin plus vancomycin may be useful in treating pan-resistant A. baumannii infections.

Essential Oil from Berries of Lebanese Juniperus excelsa M. Bieb Displays Similar Antibacterial Activity to Chlorhexidine but Higher Cytocompatibility with Human Oral Primary Cells.

Chlorhexidine (CHX), one of the most effective drugs administered for periodontal treatment, presents collateral effects including toxicity when used for prolonged periods; here, we have evaluated the bactericidal potency and the cytocompatibility of Juniperus excelsa M. Bieb essential oil (EO) in comparison with 0.05% CHX. The EO was extracted from berries by hydrodistillation and components identified by gas chromatography and mass spectrometry. Bacterial inhibition halo analysis, quantitative cell viability 2,3-bis(2-methoxy-4-nitro-5-sulphophenyl)-5-[(phenyl amino) carbonyl]-2H-tetrazolium hydroxide assay (XTT), and colony forming unit (CFU) count were evaluated against the two biofilm formers Aggregatibacter actinomycetemcomitans and Streptococcus mutans. Finally, cytocompatibility was assessed with human primary gingival fibroblasts (HGF) and mucosal keratinocytes (HK). The resulting EO was mainly composed of monoterpene hydrocarbons and oxygenated monoterpenes. An inhibition halo test demonstrated that both bacteria were sensitive to the EO; XTT analysis and CFU counts confirmed that 10-fold-diluted EO determined a statistically significant (p < 0.05) reduction in bacteria count and viability towards both biofilm and planktonic forms in a comparable manner to those obtained with CHX. Moreover, EO displayed higher cytocompatibility than CHX (p < 0.05). In conclusion, EO exhibited bactericidal activity similar to CHX, but a superior cytocompatibility, making it a promising antiseptic alternative to CHX.

Effect of Feeding Raw Versus Heat-treated Colostrum on Passive Transfer of Immunoglobulin Gin Newborn Dairy Calves

The importance of timing, volume and quality of colostrum fed has long been understood, but the improvement of colostrum quality via on farm heat-treatment is a concept developed only within the last few years. Bacterial contamination of colostrum is not only a potential source of pathogen exposure, but perhaps interferes with the absorption of lg. An earlier pilot study in 49 calves on one farm indicated that feeding heat-treated colostrum enhanced the efficiency of absorption of colostral IgG in the neonatal calf, presumably by reduction in bacteria counts in colostrum. A larger controlled study in six large commercial dairies was undertaken to determine if the pilot study results could be replicated. The objective of this study was to determine if calves fed raw versus heat-treated colostrum differed significantly in serum total solids and serum IgG concentrations.

Preparation and characterization of silver containing chitosan fibers

AbstractSilver containing chitosan fibers were prepared by blending fine particles of a silver sodium hydrogen zirconium phosphate compound into the spinning solution. It was possible to distribute the silver containing particles in the chitosan fiber because of the high viscosity of the spinning solution and the small diameter of the particles. Because the silver ions are imbedded inside the sodium hydrogen zirconium phosphate complex, the chitosan fibers remain white in color without being oxidized by the silver ions. The release of silver ions from the silver containing chitosan fibers were studied by placing the fibers in contact with distilled water, solution A, and aqueous protein solutions. Results showed that the release of silver ions was low in water, while in solution A and protein solutions, the silver ions are activated through ion exchange and chelation. The silver ions can significantly enhance the antimicrobial properties of the chitosan fibers. Experimental results showed that when placed in contact with the silver containing chitosan fibers, the reduction in bacteria count can be more than 98%. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3622–3627, 2007

Lethal photosensitization of oral pathogens via red‐filtered halogen lamp

OBJECTIVE OF INVESTIGATION: The ability of laser irradiation in the presence of photosensitizing agent to induce lethal effect on oral bacteria is well documented. We designed an in-vitro experiment to achieve phototoxic results on two common oral pathogens, using a high intensity, red filtered halogen lamp. Our goal was to determine the minimum duration of light exposure and drug dilution to achieve at least 50% reduction in bacteria counts. Two common oral pathogens, Porphyromonas gingivalis and Prevotella intermedia were used in experiments. The source for light energy was a continuous working, high intensity, red filtered, halogen lamp (HL) with light transmitted through a flexible light guide over petri dishes containing live bacteria. Microorganisms were exposed to light for 5, 10 and 20 min. Methylene Blue (MB) in concentrations of 0.1, 0.075, 0.05, 0.025 and 0.01% was used as a photosensitizing agent. Light energy alone and MB alone was used as controls. Optimum lethal photosensitization (50% or more bacteria killing) of oral pathogens was achieved using halogen light illumination for 5 min and longer with 0.05% MB or exposure to light for 20 min in the presence of 0.025 and 0.01% MB. Light exposure of 20 min in the absence of MB was not effective in killing bacteria. In the absence of light, MB at concentrations of 0.025 and 0.001% was not effective. Reduction of bacteria with the use of 0.05% MB alone was also insignificant. However, 0.075 and 0.1% MB, even in the absence of light was found to be bacteriocidal. Our in-vitro data indicate that we were able to achieve lethal photosensitization of two common oral pathogens with high intensity red filtered HL in the presence of diluted MB. In this era of increased incidence of antibiotic resistance, bacterial killing with laser or light energy in the presence of photosensitizing agent can prove to be a valuable treatment modality.

Lethal photosensitization of oral pathogens via a red-filtered halogen lamp

Problem: We designed an in vitro experiment to achieve phototoxic results on 2 common oral pathogens, using a high intensity red-filtered halogen lamp (HL). Our goal was to determine the minimum duration of light exposure and drug dilution to achieve at least 50% reduction in bacteria counts. Methods: Porphyromonas gingivalis and prevotella intermedia were used in this experiment. The source for light energy was a continuously working, high intensity, red-filtered HL. The light was transmitted through a flexible light guide over petri dishes containing live bacteria. Microorganisms were exposed to halogen light for 5, 10, and 20 minutes. Methylene blue (MB) in concentrations of 0.1%, 0.075%, 0.05%, 0.025%, and 0.01% was used as a phosensitizing agent. Light energy alone and MB alone was used as controls. Results: Optimum lethal photosensitization (50% or more bacteria killing) of oral pathogens was achieved under the following conditions: (1) HL illumination for 5 minutes and longer with 0.05% MB; (2) exposure to light for 20 minutes in the presence of 0.025% and 0.01% MB. Light exposure for 20 minutes in the absence of MB was not effective in killing bacteria. In the absence of light, MB at concentrations of 0.025% and 0.001% was not effective. Reduction of bacteria with the use of 0.05% MB alone was also insignificant. However, 0.075% and 0.1% MB, even in the absence of light was found to be bacteriocidal. Conclusion: Our in vitro data indicate that we were able to achieve lethal photosensitization of 2 common oral pathogens with a high-intensity red-filtered HL in the presence of diluted MB. Significance: In this era of increased incidence of antibiotic resistance, bacterial killing with laser or light energy in the presence of photosensitizing agents can prove to be a valuable treatment modality. Support: Support from Otolaryngology Research and Education Foundation

Ex-vivo treatment of gastric Helicobacter infection by photodynamic therapy

Attempts to develop PDT for eradication of Helicobacter infection have only been successful in vitro. We have investigated the effect of topical sensitization (except ALA) of Helicobacter mustelae on explanted ferret gastric mucosa using one of five sensitizers (methylene blue (MB), toluidine blue O (TBO), phthalocyanine, haematoporphyrin derivative and 5-aminolavulinic acid), followed by irradiation with an appropriately tuned copper vapour pumped dye laser. A 90% reduction in counts of bacteria sensitized with 0.75 mg TBO kg −1 were seen after irradiation with 200 J cm −2. Concentrations of MB of 0.75 mg kg −1 and 7.5 mg kg −1 were not toxic to H. mustelae, but the further addition of 20 J cm −2 laser light reduced colony counts by more than 99%. MB at a concentration of 75 mg kg −1 exhibited significant dark toxicity towards H. mustelae, but further addition of 20 J cm −2 laser light resulted in near eradication of all colonies. The remaining three compounds were ineffective. Finally, we studied the microscopic fluorescence distribution of MB (7.5 mg kg −1) on ferret gastric mucosa after topical administration. Fluorescence was greatest in the superficial mucosal layer, upon which lies the bacteria. However, from experiments on rats, the energy required to kill the sensitized bacteria was insufficient to damage the underlying mucosa. We conclude that Helicobacter can be killed on host mucosal epithelium following topical administration of MB and subsequent exposure to laser light.

Preoperative Use of Povidone-Iodine

One hundred one adult orthopedic surgical patients were studied in a randomized, prospective clinical trial to compare the effectiveness of the standard povidone-iodine scrub and paint with povidone-iodine painting alone for presurgical skin preparation. No infections occurred in either group. The scrub-plus-paint group showed a 0.601 logarithmic reduction in bacteria counts, compared with 0.622 with painting alone. Further, 36.8% of the patients in the scrub-plus-paint group had skin counts that actually increased after preparation, compared with 13.8% of patients in the paint-only group. The preparation bacterial counts among inpatients, who received preoperative hexachlorophene showers, were significantly lower than that of outpatients, who did not receive preoperative showers. The data support the use of the preoperative hexachlorophene shower and the omission of scrubbing from the surgical skin preparation technique.

The Lethal Effectiveness of Ultra Violet Rays Applied to Milk

Summary 1. The lethal effectiveness of ultra violet energy applied to smooth flowing milk films is dependent upon the intensity and spectral characteristics of the radiation employed. 2. A greater bactericidal effect was obtained by ultra violet radiation applied to smooth flowing milk films than was obtained from films flowing over a corrugated cooler surface. 3. The effectiveness of the lethal radiation was relatively greater per unit volume of milk when applied to flowing films than when applied to stationary films having the thickness of an adhesion layer only. 4. Short ultra violet radiation predominantly in the 2200–2300 A region gave erratic bactericidal results with evidence that sub-lethal doses may cause stimulation. 5. The total lethal effect of ultra violet energy and elevated temperatures simultaneously applied for less than one second appears to be an additive process. 6. Percentage reduction in bacteria counts of raw mixed milk in excess of 90 per cent and frequently up to 95 to 98 per cent may be obtained with a high degree of regularity by preferred methods of applying ultra violet radiation of appropriate intensity and spectral characteristics.