Residual Colony-forming Units Research Articles

Antifungal effect of silver nitrate on prosthodontic dentures

Background/Aim: Although there are studies about the antimicrobial activity of silver, there is no study evaluating it as a denture disinfectant. The purpose of this study was to explore the effectiveness of 6 disinfectant solutions (50% vinegar, 100% vinegar, 1% silver nitrate, 2% silver nitrate, %1 sodium hypochlorite, 0,12% chlorhexidine digluconate) in the disinfection of acrylic resin specimens contaminated in vitro by Candida albicans, as measured by residual colony-forming unit (CFU). Material and Methods: 66 pieces of 10mmx2mm acrylic resin disc samples were prepared and incubated in 1x106 cell/ml suspension of C. albicans ATCC 18804 for 24 h (one of them as a control, n=11/group). The specimens were then transferred into tubes containing 10 ml of the tested disinfectants and kept for 10 minutes in the disinfectant. After washing with saline, the specimens were vortexed to remove the microorganisms adhered to the surfaces. Colony counting of the collected microorganisms was performed on Sabouroud dextrose medium using 10-1, 10-2 and 10-3 dilutions. The results were analysed using Kruskal-Wallis and Mann-Whitney U tests (p<0,05). Results: The results showed that 1% sodium hypochlorite, %1 silver nitrate and 2% silver nitrate were the most effective against Candida Albicans (p<0,05), followed by 100% vinegar, 0,12% chlorhexidine digluconate and 50% vinegar (p<0,05). Conclusions: Within the boundaries of this study, we conclude that 1% silver nitrate is a promising alternative disinfectant to 1% sodium hypochlorite and performs better compared to 0,12 % chlorhexidine gluconate, 50% and 100% vinegar.

Successful Removal of Clostridioides Difficile Spores and Pathogenic Bacteria From a Launderable Barrier Using a Commercial Laundry Process.

Background:To properly clean and disinfect hospital mattresses, bed manufacturers recommend a 3- to 6-step process to remove all pathogenic bacteria. An alternative is to use a removable barrier on the mattress, which is laundered after each use. The current study was to determine efficacy of a commercial laundry process in eliminating Clostridioides difficile (C diff) spores, Mycobacterium terrae (M terrae), methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa (P aeruginosa), Klebsiella pneumoniae (K pneumoniae), and Escherichia coli (E coli) from a barrier.Methods:A test barrier received 3 unique microbial suspensions in separate locations, each suspension having a known quantity of specific microorganisms: C diff spores, M terrae, and a mixed suspension of MRSA, S aureus, P aeruginosa, K pneumoniae, and E coli. A wash load contained the test barrier and 11 additional ballast barriers. Various soils were spread onto the barriers to simulate heavy soiling that may occur in a wash load: Each barrier received a small amount of mixed soil, 50% received urine, 25% received blood, and 25% received a large amount of additional mixed soil. The load was laundered using 71°C (160°F) water, detergent, and chlorine bleach, with final drying at 71°C (160°F). After laundering, remaining colony-forming units (CFUs) of each microorganism were counted at the applied locations. Each test was replicated 3 times. Industry-accepted methods were used to produce suspensions, apply inoculum, and recover organisms after laundering.Results:Before laundering, test barriers contained at least 7.0 log10 cfu/mL of each microorganism distributed over 103 cm2. After laundering, in all cases, no residual CFUs were detected over the test area, resulting in greater than 6.0 log10 reductions for every organism. (P < .05).Conclusions:Under extreme test conditions including the presence of soil, the laundry process removed all detectable pathogenic bacteria and spores from the barrier.

Effects of photodynamic laser and violet-blue led irradiation on Staphylococcus aureus biofilm and Escherichia coli lipopolysaccharide attached to moderately rough titanium surface: in vitro study.

Effective decontamination of biofilm and bacterial toxins from the surface of dental implants is a yet unresolved issue. This study investigates the in vitro efficacy of photodynamic treatment (PDT) with methylene blue (MB) photoactivated with λ 635nm diode laser and of λ 405nm violet-blue LED phototreatment for the reduction of bacterial biofilm and lipopolysaccharide (LPS) adherent to titanium surface mimicking the bone-implant interface. Staphylococcus aureus biofilm grown on titanium discs with a moderately rough surface was subjected to either PDT (0.1% MB and λ 635nm diode laser) or λ 405nm LED phototreatment for 1 and 5min. Bactericidal effect was evaluated by vital staining and residual colony-forming unit count. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, discs coated with Escherichia coli LPS were treated as above before seeding with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Both PDT and LED phototreatment induced a statistically significant (p < 0.05 or higher) reduction of viable bacteria, up to -99 and -98% (5min), respectively. Moreover, besides bactericidal effect, PDT and LED phototreatment also inhibited LPS bioactivity, assayed as nitrite formation, up to -42%, thereby blunting host inflammatory response. Non-invasive phototherapy emerges as an attractive alternative in the treatment of peri-implantitis to reduce bacteria and LPS adherent to titanium implant surface without causing damage of surface microstructure. Its efficacy in the clinical setting remains to be investigated.

The effects of diode laser on Staphylococcus aureus biofilm and Escherichia coli lipopolysaccharide adherent to titanium oxide surface of dental implants. An in vitro study.

Effective decontamination of biofilm and bacterial toxins from the surface of dental implants is a yet unresolved issue. This in vitro study aims at providing the experimental basis for possible use of diode laser (λ 808nm) in the treatment of peri-implantitis. Staphylococcus aureus biofilm was grown for 48h on titanium discs with porous surface corresponding to the bone-implant interface and then irradiated with a diode laser (λ 808nm) in noncontact mode with airflow cooling for 1min using a Ø 600-μm fiber. Setting parameters were 2W (400J/cm2) for continuous wave mode; 22μJ, 20kHz, 7μs (88J/cm2) for pulsed wave mode. Bactericidal effect was evaluated using fluorescence microscopy and counting the residual colony-forming units. Biofilm and titanium surface morphology were analyzed by scanning electron microscopy (SEM). In parallel experiments, the titanium discs were coated with Escherichia coli lipopolysaccharide (LPS), laser-irradiated and seeded with RAW 264.7 macrophages to quantify LPS-driven inflammatory cell activation by measuring the enhanced generation of nitric oxide (NO). Diode laser irradiation in both continuous and pulsed modes induced a statistically significant reduction of viable bacteria and nitrite levels. These results indicate that in addition to its bactericidal effect laser irradiation can also inhibit LPS-induced macrophage activation and thus blunt the inflammatory response. The λ 808-nm diode laser emerges as a valuable tool for decontamination/detoxification of the titanium implant surface and may be used in the treatment of peri-implantitis.

DNA vaccination based on pyolysin co-immunized with IL-1β enhances host antibacterial immunity against Trueperella pyogenes infection

Trueperella pyogenes is a commensal and opportunistic pathogen normally causes mastitis, liver abscesses and pneumonia of economically important livestock. To date, no specific control measure was reported to prevent T. pyogenes infections. In this study, we first constructed a recombinant plasmid pVAX1-PLO based on the main virulent factor pyolysin gene as DNA vaccine against T. pyogenes infection. Subsequently, transient expression of pVAX1-PLO and pcDNA3.1/V5-fIL-1β were identified in Human embryonic kidney cells (HEK293T) by immunofluorescence assay. Humoral and cellular immune responses were evaluated in mice to compare the immunogenicity between different immunized groups. The results showed that the successful expression of PLO or fIL-1β protein was detected by confocal microscopy for cells transfected with plasmid pVAX1-PLO and/or pcDNA3.1/V5-fIL-1β. The mice immunized with pVAX1-PLO elicited a higher titer of PLO-specific antibody than the control group. The levels of IFN-γ and IL-2 were significantly increased in the pVAX1-PLO immunized mice, while the expression level of IL-4 was slightly increased but not significant. These findings suggested that the DNA vaccine pVAX1-PLO can primarily induce Th1 immune response. The residual Colony-Forming Units (CFUs) from the liver and peritoneal fluid were decreased obviously in the pVAX1-PLO treated mice compared with the control. Importantly, co-immunization with pcDNA3.1/V5-fIL-1β and pVAX1-PLO could enhance host humoral and cellular immune responses and significantly protect mouse from T. pyogenes infection. In conclusion, our study provides a promising strategy against T. pyogenes infections and implies the potential clinical application of combined DNA vaccines in diseases control.

Effectiveness of Six Different Disinfectants on Removing Five Microbial Species and Effects on the Topographic Characteristics of Acrylic Resin

The aim of this study was to evaluate the effectiveness of disinfectant solutions (1% sodium hypochlorite, 2% chlorhexidine digluconate, 2% glutaraldehyde, 100% vinegar, tabs of sodium perborate-based denture cleanser, and 3.8% sodium perborate) in the disinfection of acrylic resin specimens (n = 10/group) contaminated in vitro by Candida albicans, Streptococcus mutans, S. aureus, Escherichia coli, or Bacillus subtilis as measured by residual colony-forming unit (CFU). In a separate experiment, acrylic resin was treated with disinfectants to monitor potential effects on surface roughness, Ra (microm), which might facilitate microbial adherence. Three hundred fifty acrylic resin specimens contaminated in vitro with 1 x 10(6) cells/ml suspensions of standard strains of the cited microorganisms were immersed in the disinfectants for 10 minutes; the control group was not submitted to any disinfection process. Final counts of microorganisms per ml were performed by plating method for the evaluation of microbial level reduction. Results were compared statistically by ANOVA and Tukey's test (p< or = 0.05). In a parallel study aiming to evaluate the effect of the tested disinfectant on resin surface, 60 specimens were analyzed in a digital rugosimeter before and after ten cycles of 10-minute immersion in the disinfectants. Measurements of superficial roughness, Ra (mum), were compared statistically by paired t-test (p< or = 0.05). The results showed that 1% sodium hypochlorite, 2% glutaraldehyde, and 2% chlorhexidine digluconate were most effective against the analyzed microorganisms, followed by 100% vinegar, 3.8% sodium perborate, and tabs of sodium perborate-based denture cleanser. Superficial roughness of the specimens was higher after disinfection cycles with 3.8% sodium perborate (p= 0.03) and lower after the cycles with 2% chlorhexidine digluconate (p= 0.04). Within the limits of this experiment, it could be concluded that 1% sodium hypochlorite, 2% glutaraldehyde, 2% chlorhexidine, 100% vinegar, and 3.8% sodium perborate are valid alternatives for the disinfection of acrylic resin.

Effectiveness of electrochemically activated water as an irrigant in an infected tooth model

To test the effectiveness of electrochemically activated aqueous solutions in the debridement of Enterococcus faecalis biofilms in root canals of extracted teeth. Extracted, human, single-rooted teeth (198) assembled into 11 sets (n = 18) with matching anatomical characteristics were randomly assigned to eight experimental groups. After decoronation, the root canals were prepared to a standard size. Enterococcus faecalis biofilms were grown in the root canals of autoclaved, individually mounted teeth over 48 h. Electrolysed saline collected as anolyte at the anode and catholyte at the cathode were the test agents. The four ultrasonication and four without ultrasonication irrigant groups included: neutral anolyte (NA) (pH 6.5), acidic anolyte (AA) (pH 3.0), catholyte (C) (pH 11.5) and C alternated with neutral anolyte (C/NA). Phosphate-buffered saline (PBS) with and without ultrasonication formed negative and NaOCl (3%) positive control groups. After irrigation, root canal samples were serially diluted, cultured and enumerated. The data were analysed as ratios of residual colony-forming units (CFUs) in PBS versus the test irrigants and using multivariate regression. The NA and NA (ultrasonicated, U), C/NA and AA (U) groups had significantly (alpha = 0.05) less and C (U) and C/NA (U) significantly (alpha = 0.05) more bacteria (CFUs mL(-1)) compared with their respective PBS controls. Ultrasonicated C/NA had significantly (alpha = 0.05) higher CFU counts than the nonultrasonicated solution. Other comparisons between ultrasonic and nonultrasonic groups were not significant. Of the nonultrasonicated groups, C/NA and NA were most effective, whilst of the ultrasonicated groups, AA and NA were most effective. None of these was as effective as 3% NaOCl. All but two groups (AA and C) were significantly different from their PBS controls. There was a significant difference between the C/NA groups with and without ultrasonication but not between other combinations. NA (U) and AA (U) were the most effective test solutions but NaOCl (3%) gave by far the highest bacterial kills.

Effector molecules of the host defence mechanism against Mycobacterium avium complex: the evidence showing that reactive oxygen intermediates, reactive nitrogen intermediates, and free fatty acids each alone are not decisive in expression of macrophage antimicrobial activity against the parasites.

In this study, we evaluated the roles of reactive oxygen intermediates (ROI), reactive nitrogen intermediates (RNI), and free fatty acids (FFA) as effectors of the macrophage-mediated host defence mechanism against Mycobacterium avium complex (MAC). First, M. avium (three strains) and M. intracellulare (two strains) were treated with the H2O2-Fe2+-mediated halogenation system, acidified NaNO2-derived RNI, or FFA (linolenic acid) in sodium acetate buffer pH 5.5, and then counted for the number of residual colony-forming units (CFU) of organisms. Although these effectors exerted strong bactericidal activity against the MAC, the susceptibility of test organisms markedly varied from strain to strain. There was no significant relationship between the degree of resistance of a given MAC strain to these effectors and its virulence in mice, indicating that ROI, RNI, and FFA each alone are not decisive as the effector components of the host defence mechanism against the MAC. Second, the increase in ROI-producing ability in murine peritoneal macrophages due to tumour necrosis factor-alpha (TNF-alpha) treatment was not accompanied by parallel potentiation of anti-MAC activity of the same macrophage population. This excludes the possibility that ROI play a central role in macrophage-mediated killing and inhibition of MAC organisms. Third, anti-MAC activity of BAM3 macrophage cell line was not significantly attenuated by N(G)-monomethyl-L-arginine (NO synthase-inhibitor causing reduction of RNI production) or by quinacrine (phospholipase A2-inhibitor causing reduction of FFA release), indicating that RNI and FFA each alone do not play crucial roles in the expression of macrophage antimicrobial activity against the MAC. The present findings suggest important roles of collaborating actions of various antimicrobial effectors and/or the participation of other kinds of effectors in macrophage-mediated killing and inhibition of MAC organisms.

Comparison of Topical Ciprofloxacin to Conventional Antibiotic Therapy in the Treatment of Experimental Pseudomonas aeruginosa Keratitis

We evaluated the efficacy of topical ciprofloxacin (3.0 mg/ml) in the treatment of experimental Pseudomonas aeruginosa keratitis in 60 rabbits. We compared ciprofloxacin treatment with double drug therapy consisting of tobramycin (13.6 mg/ml) plus polymyxin B (25,000 U/ml) or carbenicillin (6 mg/L). Two strains of P. aeruginosa were used. One was a strain well characterized for use in experimental Pseudomonas keratitis (ATCC organism 27853); the second was an organism from a patient with a Pseudomonas corneal ulcer. Rabbits were treated for 16 h, after which the corneas were excised, homogenized, and plated serially for residual colony-forming units. Both organisms responded significantly better to topical off-the-shelf ciprofloxacin than to therapy with two conventional antipseudomonal fortified antibiotic drugs (p < or = 0.0001).

Origin and Recovery of Colony-forming Units in Locally Curetted Bone Marrow of Mice

Abstract Histologic study of locally curetted bone marrow showed a sequence of blood clot formation, displacement of the clot by a primitive reticular tissue, and hematopoietic regeneration. Histologic regeneration of sinusoidal vessels, and recovery was incomplete 12 wk later with increased fat, residual trabecular bone, and cystic areas. Recovery of colony-forming units (CFU) paralleled hematopoietic cellular recovery and did not exceed levels of 70% of normal by 12 wk postcurettage. Transplantation of cureted and irradiated mice with T6T6 marker chromosomes demonstrated that cells with marker chromosomes migrated readily into irradiated marrow but were excluded from the curetted marrow for 2 wk after curettage. Three weeks after, curettage marker cells gained ready access to curetted marrow. The early exclusion but later appearance of transplanted marker cells was correlated with the early absence and later regeneration of sinusoidal vessels. The histologic and cytogenetic studies support the concept of a dependence of hematopoiesis upon a sinusoidal system with an appropriate marrow microenvironment. These studies support the concept of a local origin of marrow regeneration within curetted cavities but do not indicate whether the hematopoietic tissue originates from small numbers of residual CFU surviving curettage or from multipotential reticular cells. There was no evidence of a stimulatory effect upon uncuretted marrow by the action of curettage.