Reduction In Number Of Bacteria Research Articles

Repetitive combined doses of bacteriophages and gentamicin protect against Staphylococcus aureus implant-related infections in Galleria mellonella.

Bacteriophages infect, replicate inside bacteria, and are released from the host through lysis. Here, we evaluate the effects of repetitive doses of the Staphylococcus aureus phage 191219 and gentamicin against haematogenous and early-stage biofilm implant-related infections in Galleria mellonella. For the haematogenous infection, G. mellonella larvae were implanted with a Kirschner wire (K-wire), infected with S. aureus, and subsequently phages and/or gentamicin were administered. For the early-stage biofilm implant infection, the K-wires were pre-incubated with S. aureus suspension before implantation. After 24 hours, the larvae received phages and/or gentamicin. In both models, the larvae also received daily doses of phages and/or gentamicin for up to five days. The effect was determined by survival analysis for five days and quantitative culture of bacteria after two days of repetitive doses. In the haematogenous infection, a single combined dose of phages and gentamicin, and repetitive injections with gentamicin or in combination with phages, resulted in significantly improved survival rates. In the early-stage biofilm infection, only repetitive combined administration of phages and gentamicin led to a significantly increased survival. Additionally, a significant reduction in number of bacteria was observed in the larvae after receiving repetitive doses of phages and/or gentamicin in both infection models. Based on our results, a single dose of the combination of phages and gentamicin is sufficient to prevent a haematogenous S. aureus implant-related infection, whereas gentamicin needs to be administered daily for the same effect. To treat early-stage S. aureus implant-related infection, repetitive doses of the combination of phages and gentamicin are required.

Graphene-Based TiO2 Cement Composites to Enhance the Antibacterial Effect of Self-Disinfecting Surfaces

This paper studies the photocatalytic performance of graphene-based titanium dioxide (TiO2) on cementitious composites for the decomposition of Escherichia coli (E. coli) under visible light. Graphene-based TiO2 was first synthesized through a hydrothermal process. The composites were then evaluated in terms of adsorption capability and degradation of methylene blue dyes. The adsorption test shows a remarkable increase in the amount of dye adsorbed into the composite surface. GO-P25 could adsorb around 60% of the initial dye, while less than 10% of the initial dye was adsorbed by pristine TiO2-P25. The synthesized graphene-based TiO2 significantly enhanced the dye degradation activity (94%) compared to pristine P25 (36%) and Krono (52%), even with the longer irradiation time for P25 and Krono. This led to an increase in reaction rate that was almost 20 times that of P25. Considering the good adsorption capabilities and high photodegradation of dye under visible light for GO-P25, cement-based surfaces containing GO-P25 are expected to be improved for the decomposition of Escherichia coli (E. coli) under visible light. Graphene-based TiO2 on a cement-based surface showed high antibacterial activity with a 77% reduction in number of bacteria compared to a cement-based surface containing pristine TiO2. This study confirms the effectiveness of the composites for disinfection of E. coli under visible light.

EFEKTIVITAS DAUN SIRIH MERAH (Piper crocatum) PADA SANITASI DI RUANG PENAMPUNGAN SUSU

Red betel is a multipurpose plant, because apart from being an ornamental plant, because of the beauty of its leaves, it also has several active compounds as antibacterial agents. The aim of this research was to study the effectiveness of red betel leaf extract as a natural disinfectant in the milk storage room through its inhibitory power against bacteria in situ and its effect on reducing the number of total bacteria on the floor, table, and walls in the milk storage room. The research used experimental method using completely randomized design with 3 treatments of red betel leaf extract concentration, P1 = 15%, P2 = 25%, P3 = 35%, each treatment was repeated 6 times. The research data were analyzed using analysis of variance and Tukey's test. The results showed that the highest reduction in the total number of bacteria was in the red betel leaf extract with a concentration of 35%, both on the floor, table, and walls in the milk storage room, respectively 52.40%, 59.96%, and 61.77%. The inhibition zone of red betel leaf extract against bacteria in situ was the highest at a concentration of 35% red betel leaf extract on the floor, table and wall, namely 9.12; 10.65; and 10.76 mm.

An ex vivo evaluation of antimicrobial efficacy of root canal preparation with hand K-files, hand Pro Taper, and Pro Taper rotary files

Background:Microorganisms are considered to be the primary cause behind persistent pulpoperiapical pathologies as well as endodontic failures. It has been found that Enterococcus faecalis is one of the most commonly isolated organisms in failed endodontic treatment. Proper and appropriate mechanical instrumentation is necessary to eradicate these microorganisms.Aims and Objectives:The aim of this study was to compare antimicrobial efficacy of various root canal instrumentation techniques. This study was designed to compare antimicrobial efficacy of root canal preparation using hand K-files, hand Pro Taper files, and Pro Taper rotary files.Materials and Methods:Forty intact maxillary premolars extracted for orthodontic reasons were used. After extirpation of pulp, teeth are decoronated and autoclaved. Then the root canals were infected with E. faecalis suspension and the teeth were incubated at 37°C for 24 h. Thereafter the teeth were divided into five groups and were prepared using the following instruments: group 1 (hand K-files), group 2 (hand Pro Taper files), group 3 (Pro Taper rotary files), group 4 (Control I; treatment consists of irrigation with 1 mL of sterile physiological saline with no instrumentation), and group 5 (Control II; teeth received no treatment at all). Before and after treatments, samples were taken from the root canals for culture and were transferred to physiological saline. Results were evaluated after 24-h incubation in selective culture medium.Results:The results showed that the teeth prepared with Pro Taper rotary files showed significant reduction in number of bacteria from the root canals.

An in vivo comparison of the antibacterial efficacy of photoactivated disinfection, diode laser, and 5% sodium hypochlorite in root canal disinfection.

Background:Pulpal infections are caused by varied number of organisms and are located in various sites of root canal system. Thus, the success of root canal treatment depends on complete eradication of microbiota.Materials and Methods:Thirty-two patients were selected and divided into four groups (photoactivated disinfection [PAD], diode laser, 5% sodium hypochlorite [NaOCl], and normal saline). The treatment was done according to groups, following manufacturer's instructions. The efficacies of groups were evaluated using microbial culturing technique. Three samples were taken for each group and were incubated separately for aerobic and anaerobic culture. Microbial counting was done for each sample in the form of colony-forming units.Results:It was evaluated using two-way analysis of variance and Friedman test. All the groups showed reduction in number of bacteria. However, for group A P < 0.0001 when analyzed for aerobic and anaerobic microorganisms, whereas, with Group B and C, P < 0.0001 for aerobic microorganisms.Conclusion:PAD, diode laser, and 5% NaOCl showed antibacterial action against aerobic and anaerobic bacteria.

Studiu clinic şi microbiologic privind contaminarea microbiană a unor materiale de amprentă uzuale în medicina dentară

Mass distribution of different infectious diseases appears even more likely in dentistry than other medical specialities. The purpose of the study is to examine different impressions with alginate materials in order to demonstrate the contamination with different pathogens. Material and method. 63 patients were included in this study. They required specific prosthetic treatment. Preliminary impression were obtained with irreversible hydrocolloid material and microbiologically tested shorthy after removal from the mouth, after washed throughly with cold water and after decontamination with specific desinfectants. Results. Microbiologic records on the alginate impressions in different stages, revealed a reduction in number of bacteria, but not completely absence, regardless of the type of decontamination substance. Conclusions. The presence of different pathogens on the surface of irreversible hydrocolloid impresions is certain. There are residual bacteria which differ from one substance to another, irrespective of cleaning stages and decontamination materials used in daily manipulation of dental impresion. Even if time consuming, decontamination of alginate impression is compulsory in dentistry.

Modeling the effect of temperature on survival rate of Salmonella Enteritidis in yogurt

The aim of the study was to determine the inactivation rates of Salmonella Enteritidis in commercially produced yogurt and to generate primary and secondary mathematical models to predict the behaviour of these bacteria during storage at different temperatures. The samples were inoculated with the mixture of three S. Enteritidis strains and stored at 5 degrees C, 10 degrees C, 15 degrees C, 20 degrees C and 25 degrees C for 24 h. The number of salmonellae was determined every two hours. It was found that the number of bacteria decreased linearly with storage time in all samples. Storage temperature and pH of yogurt significantly influenced survival rate of S. Enteritidis (p < 0.05). In samples kept at 5 degrees C the number of salmonellae decreased at the lowest rate, whereas at 25 degrees C the reduction in number of bacteria was the most dynamic. The natural logarithm of mean inactivation rates of Salmonella calculated from primary model was fitted to two secondary models: linear and polynomial. Equations obtained from both secondary models can be applied as a tool for prediction of inactivation rate of Salmonella in yogurt stored under temperature range from 5 to 25 degrees C; however, polynomial model gave the better fit to the experimental data.

Microbiology of Broiler Carcasses and Chemistry of Chiller Water as Affected by Water Reuse

A study was conducted to determine the effects of treating and reusing poultry chiller water in a commercial poultry processing facility. Broiler carcasses and chiller water were obtained from a commercial processing facility which had recently installed a TOMCO Pathogen Management System to recycle water in sections 2 and 3 of two 3-compartment chillers. In this system, reused water is blended with fresh water to maintain the chiller volume. Carcasses were sampled prechill and postchill (final exit), and chiller water was sampled from the beginning and end of each of the 3 sections. Carcasses were subjected to a whole carcass rinse (WCR) in 0.1% peptone. Numbers of Escherichia coli (EC), coliforms (CF), and Campylobacter (CPY) were determined from the WCR and chiller water samples. Prevalence of Salmonella (SAL) was also determined on the WCR and chiller water samples. On average, prechill levels of bacteria recovered from rinses were 2.6, 2.9, and 2.6 log10 cfu/mL for EC, CF, and CPY, respectively. Ten out of 40 (25%) prechill carcasses were positive for SAL. After chilling, numbers of EC, CF, and CPY recovered from carcass rinses decreased by 1.5, 1.5, and 2.0 log10 cfu/mL, respectively. However, 9 out of 40 (22%) postchill carcasses were positive for SAL. When the chiller water samples were tested, counts of EC, CF, and CPY were found only in water collected from the first section of the chiller (inlet and outlet). Two of 4 water samples collected from the inlet of the first section tested positive for SAL. This study shows that fresh and reused water can be used to cool poultry in chiller systems to achieve a reduction in numbers of bacteria (EC, CF, and CPY) or equivalent prevalence (SAL) of bacteria recovered from broiler carcasses.

Efficacy of live Chlamydophila abortus vaccine 1B in protecting mice placentas and foetuses against strains of Chlamydophila pecorum isolated from cases of abortion

The efficacy of Chlamydophila abortus vaccine strain 1B in protecting against two selected Chlamydophila pecorum strains, isolated from an aborted goat (M14) in Morocco and a ewe (AB10) in France, was investigated in a mouse model, by comparing the reduction in number of bacteria in the placentas of vaccinated mice challenged intraperitoneally at 11 days of pregnancy with the reference C. abortus (AB7) and C. pecorum (M14, or AB10) strains, to those of unvaccinated mice. Vaccine 1B was shown to provide effective protection against the field strains of C. pecorum, since it significantly reduced the placental Chlamydophila colonisation. The two C. pecorum strains were not sufficiently abortifacient in mice to use reduction in abortion as a criterion of protection.

The effects of exposure at constant (1 h) or exponentially decreasing concentrations of quinupristin/dalfopristin on biofilms of Gram-positive bacteria.

Using a biofilm model, infections by Staphylococcus aureus, coagulase-negative staphylococci and enterococci were studied. The biofilms were exposed to quinupristin/dalfopristin and five comparator antibiotics: ciprofloxacin, vancomycin, teicoplanin, flucloxacillin and erythromycin. Two methods of exposure to the drugs were used: constant for 1 h, and exponentially decreasing, with the rate of dilution being matched to the half-lives of the antibiotics. The effects of antibiotic exposure were monitored by performing viable counts on the cells eluted from the biofilms. The results are presented as the inhibitory or bactericidal effect (the reduction in numbers of bacteria eluted from the biofilms) and recovery times (the time taken for the number of cells eluted from the biofilms to return to the number eluted before the drug exposure). Quinupristin/dalfopristin was the most effective of the six antibiotics studied, especially against enterococci. However, there were no significant differences in the effects, inhibitory/ bactericidal or recovery times, produced by the two methods of exposure. The two glycopeptides showed a surprising lack of activity.

Distribution and significance of heterotrophic marine bacteria with antibacterial activity.

Bacteria with antibacterial activity were isolated from seawater, sediments, phytoplankton, and zooplankton of Suruga, Sagami, and Tokyo Bays and from soft corals and sponges collected from the Taiwan coast. Of the 726 strains isolated, 37 showed antibacterial activity against either Vibrio parahaemolyticus (ATCC 17802) or Staphylococcus aureus (P209). Sediment harbored the lowest number of these forms of bacteria, and those from Tokyo Bay did not show any activity. Attached isolates showed greater activity compared with free-living forms. Relatively high numbers of strains with antibacterial activity were associated with phytoplankton. Among the zooplankton isolates, cladocerans harbored the maximum number of antibacterial strains. Isolates were more inhibitory to gram-positive test cultures. Autoinhibition was observed only among 8% of the isolates. Marine nonproducers were more susceptible. Pseudomonas/Alteromonas species made up 81.0% of isolates, of which 30% were pigmented strains. The absence or reduction in number of bacteria with antibacterial activity in Tokyo Bay is attributed to its eutrophic nature, which may tend to moderate the production of antibacterial compounds.

Microbicidal activity of octenidine hydrochloride, a new alkanediylbis[pyridine] germicidal agent.

The potential of octenidine hydrochloride (WIN 41464-2) as a topical microbicide was measured both by in vitro death kinetics and reductions in numbers of bacteria on the skin of cynomolgus monkeys. Semilogarithmic survival curves were plotted to measure the microbicidal activity of various concentrations of octenidine against Staphylococcus aureus. The microbicidal activity of octenidine was also determined for Staphylococcus epidermidis, Proteus mirabilis, Streptococcus pyogenes, Klebsiella pneumoniae, Escherichia coli, Pseudomonas aeruginosa, Serratia marcescens, and Candida albicans. Death rates for the same microbial strains were compared with those obtained by using chlorhexidine gluconate. Octenidine concentrations of less than 1.5 microM (0.94 microgram/ml) caused a greater than 99% reduction of each microbial population within 15 min. Staphylococcus epidermidis was the most susceptible of the test organisms, and E. coli and C. albicans were the least susceptible. Octenidine was more active than chlorhexidine against each test strain. Skin-degerming activities of aqueous and formulated octenidine and formulated chlorhexidine were compared in single and multiple applications of these agents to the hand and foot surfaces of monkeys by using a glove-juice extraction procedure to measure the skin microflora. Aqueous octenidine, at a concentration of 0.2 to 1.6% reduced resident microflora populations from 90 to 99.98%, depending on the concentration and number of applications. Octenidine formulated at 2% in a surfactant-based vehicle exhibited significantly better skin-degerming activity than did either a nonmedicated vehicle or the Hibiclens brand of 4% chlorhexidine gluconate.

Disinfection of circulating water systems by ultraviolet light and halogenation

Continuous ultraviolet light (u.v.) and chemical disinfection of circulating water systems were evaluated. Direct comparisons of the biocidal effectiveness of u.v. light vs halogenation were tested with Legionella spp and Pseudomonas aeruginosa because of their association with the acquisition of overt clinical disease from water-containing appliances. Findings indicated that six species of Legionella and P. aeruginosa were killed by a moderate level of u.v. radiation. L. pneumophila and other bacteria in a circulating water system were effectively killed by a biocidal u.v. light. However, free chlorine levels needed to kill Legionella, Pseudomonas, and Flavobacterium within 1 min were found to be greater than 4 mg ml −1. Data from a long-term field trial with u.v. light treatment of evaporative condenser water showed a significant reduction in numbers of bacteria. Ultraviolet disinfection of hospital hydrotherapy whirlpools confirmed the utility of this mode of disinfection under circumstances where chlorination may not be practical for medical reasons. These findings were confirmed during investigations of halogenated or u.v.-treated public hot tub/whirlpools. The effectiveness of routine chemical disinfection for controlling microbial flora in a cooling tower was also evaluated. The 2 month survey indicated that the numbers of bacteria, including Legionella, were not affected by two biocides that were used. The observations made during this investigation support the conclusion that u.v. light disinfection of water-containing systems may be an appropriate alternative or supplement to chemical biocides.

History, benefits and limitations of Pyrex glass particle opacity references

The Pyrex glass particle reference was prepared in the U.S.A. in 1946 to meet the need for uniformity, between laboratories, in the challenge dose for mice immunized with pertussis vaccine. Extension of use to pertussis vaccine significantly reduced the marked variability in density of vaccines claimed to have equal numbers of bacteria. In 1953, the World Health Organization Expert Committee on Biological Standardization (1954) designated an International Opacity Reference Preparation (IORP) for visual characterization of bacterial suspensions and assigned to it an opacity of 10 units per ml. Subsequently, problems developed in reproducibility of the preparation, in differences in evaluations of different types of bacterial suspensions and especially between visual and photoelectric measurements. Due to a slow decrease in optical density, the third IORP was about 20% less turbid than the first IORP. Nevertheless, the opacity references have been very valuable in obtaining consistency in challenge doses and reduction in numbers of bacteria in pertussis vaccine. Illustrative data were presented. The opacity preparations continue to be valuable basic frames of reference for correlations with other parameters, such as mass bacterial weight, colony forming units and nitrogen content, that can be related to potency and safety (toxicity) which are the final criteria for a vaccine. Suggestions for improvement in measurement of the bacterial mass in vaccines were given.

Ultraviolet-induced changes in populations of epiphytic bacteria on beetroot leaves and their effect on germination of Botrytis cinerea spores

There was no consistent reduction in numbers of bacteria isolated from unwetted beetroot leaves following exposure to ultraviolet light. Bacteria increased in water droplets on leaves but were readily killed by short exposures to ultraviolet light. After prolonged exposures numbers of surviving bacteria were similar to those on unwetted leaves. Evidence suggested that the rapid recolonization of leaves after ultraviolet irradiation occurred from surviving bacteria either within the leaf or protected on the surface from direct exposure. The higher numbers of bacteria which developed in water droplets placed on leaves previously exposed to ultraviolet light may have been associated with increased leakage of electrolytes, amino acids and carbohydrates from leaves following irradiation. Germination of Botrytis cinerea spores was more strongly inhibited in vitro in droplets from leaves previously exposed to ultraviolet light. The spectrum of bacterial species on leaves was changed following exposure to ultraviolet light but isolates of bacteria from irradiated leaves were not more antagonistic against B. cinerea spores in vitro.

Effect of treatment in percolating filters on the numbers of bacteria in sewage in relation to the composition and size of filtering medium.

For a period of a year the total count, Coli-aerogenes count and turbidity were determined on samples of sewage and effluent taken every week from pilot-scale percolating filters treating domestic sewage. The eight filters contained four types of filtering medium in two sizes.Numbers of coliform bacteria in the settled sewage were much higher during the warmer months but the total count showed no regular seasonal variation. Treatment in all the filters reduced the numbers of bacteria in both groups by over 95%. In general the reductions in numbers of bacteria and in numbers of all particles in suspension were proportional to the total area of filtering medium with which the sewage came into contact. The probability of discharging more than 10,000 coli-aerogenes per ml. ranged from 10% in the most efficient to 90 % in the least efficient filter.Experiments in which Serratia indica was added to the influent sewage showed that only 0·4 % were recovered in the settled effluent after 24 hr. Treatment in the filters had little selective action on the different types of coliform bacteria.This paper is published by permission of the Department of Scientific and Industrial Research.

Experimental pyelonephritis. I. Effect of ureteral ligation on the course of bacterial infection in the kidney of the rat.

A study has been made of the effect of ureteral ligation on the susceptibility of the kidney to pyogenic infection. In most experiments a strain of E. coli was employed as the test organism, being injected intravenously in varying quantity either before or after ureteral ligation. A few experiments were also carried out with S. marcescens. Preliminary observations were made on the distribution and persistence of E. coli following its inoculation into the blood stream of normal rats. Rapid reduction in number of bacteria in the circulation occurred during the first 30 minutes, but bacteriemia persisted at a comparatively low level for at least 48 hours. Large proportions of the inoculated bacteria were arrested and apparently destroyed in the liver, spleen, and lungs. Comparatively small numbers were deposited in the kidneys; nevertheless, these continued to be demonstrable during the 1st week, without notable tendency to increase or decrease, then disappeared during the 2nd week. There was no acceleration in rate of disposal of the bacteria in the kidney when a second injection was made 1 week after the first. In rats with one ureter ligated the number of bacteria lodging in the kidneys after intravenous inoculation did not differ from that found in normal animals. It appears, therefore, that the increased susceptibility of the obstructed kidney to infection via the blood stream is not attributable to an increased trapping of circulating bacteria. 4 to 6 hours after the intravenous injection, however, an increased number of bacteria could be demonstrated in the obstructed kidney, apparently due to local multiplication, and by the end of 24 hours purulent infection was usually obvious. A comparatively large number of bacteria was required to cause infection, even in the kidney with obstruction. This appeared to be related to the small proportion of the intravenous inoculum which lodged in the kidney initially. Although bacteria could be demonstrated in the normal kidney for a week or more following intravenous injection it was not possible to induce active infection with equal regularity by ligating the ureter throughout this time. During the first 3 days the majority of obstructed kidneys developed infection, but after 5 or more days this occurred in only a small proportion of animals so treated. The reason for the difference, in relation to interval between intravenous injection and time of ligation, is not apparent. When the ureter was ligated but no intravenous injection of bacteria was given, staphylococcal infection developed in the obstructed kidney within 2 weeks in about one-third of the animals. Reasons are given for the belief that this was blood-borne infection, and not the result of contamination at the time of operation. Staphylococci were not recovered from the normal rat kidney. These "spontaneous" staphylococcal infections seldom developed when E. coli was injected intravenously at the time of ureteral ligation.

The Effects of Freezing on Marine Bacteria.: I. Quantitative Studies.

When marine bacteria were exposed to a moderate freezing temperature, −16 °C., for short periods, sea-water offered greater protection than broth media or distilled water. Reduction in number of bacteria was least severe in broth media of optimum salt-concentration and hydrogen ion concentration. During freezing in distilled water, transfer of bacteria from the crystallizing portion to the liquid part occurred. Old strains were more resistant to freezing, and previous cultivation at −3° produced more resistant strains. A higher percentage of cells were killed by freezing at lower freezing temperatures, by prolonged freezing, rapid freezing and repeated freezing. In truly super-cooled sea-water higher percentage reduction occurred than in frozen sea-water at −6.5° and −10°.