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PubMed2003

TGF-beta1 increases microbial clearance but worsens lung injury during Escherichia coli pneumonia in rats.

We investigated the effects of either intravenous (IV) or intrabronchial (IB) treatment with transforming growth factor beta1 (TGF-beta1) during bacterial pneumonia in rats. Immediately following IB Escherichia coli inoculation (T0), animals (n=270) were randomized to receive a single treatment with human recombinant TGF-beta1 either via IV or IB, or via both IV and IB routes, or to receive placebo (human serum albumin, HSA) only. Blood and lung analysis was done at 6 and 168 h after E. coli inoculation. Other animals (n=40) were administered IV TGF-beta1 or HSA at T0 and 6, 12 and 24 h after E. coli inoculation to investigate the effects of multiple treatments also on survival rates alone. All animals received ceftriaxone daily. Route of administration did not influence TGF-beta1 (p=ns for the effect of TGF-beta1 comparing IV vs IB routes) and we averaged over this variable in analysis. The relative risk of death (mean +/- sem) was not altered by either single treatments administered at T0 (-0.18 +/- 0.25, p=0.47) or multiple treatments (0.40 +/- 0.50, p=0.66) of TGF-beta1. Single treatment with TGF-beta1 first decreased and then increased vascular leukocytes at 6 and 168 h, respectively, but increased alveolar leukocytes at both time points (p=0.02 comparing the differing effects of TGF-beta1 on vascular and alveolar leukocytes at 6 and 168 h). Although TGF-beta1 decreased blood and lung bacteria counts at 6 and 168 h, it also increased serum tumor necrosis factor levels and lung injury scores at these time points (p<0.05 for the effects of TGF-beta1 on each parameter at 6 and 168 h together). Thus, while increases in lung leukocyte recruitment with TGF-beta1 were associated with improved microbial clearance in this rat model of pneumonia, worsened lung injury may have negated these beneficial host defense effects, and overall survival was not significantly improved. Despite these harmful effects, additional studies may be warranted to better define the influence of exogenous TGF-beta1 on host defense during acute bacterial infections.

Animals↗
PubMed2004

A quasi-chemical model for the growth and death of microorganisms in foods by non-thermal and high-pressure processing.

Predictive microbial models generally rely on the growth of bacteria in laboratory broth to approximate the microbial growth kinetics expected to take place in actual foods under identical environmental conditions. Sigmoidal functions such as the Gompertz or logistics equation accurately model the typical microbial growth curve from the lag to the stationary phase and provide the mathematical basis for estimating parameters such as the maximum growth rate (MGR). Stationary phase data can begin to show a decline and make it difficult to discern which data to include in the analysis of the growth curve, a factor that influences the calculated values of the growth parameters. In contradistinction, the quasi-chemical kinetics model provides additional capabilities in microbial modelling and fits growth-death kinetics (all four phases of the microbial lifecycle continuously) for a general set of microorganisms in a variety of actual food substrates. The quasi-chemical model is differential equations (ODEs) that derives from a hypothetical four-step chemical mechanism involving an antagonistic metabolite (quorum sensing) and successfully fits the kinetics of pathogens (Staphylococcus aureus, Escherichia coli and Listeria monocytogenes) in various foods (bread, turkey meat, ham and cheese) as functions of different hurdles (a(w), pH, temperature and anti-microbial lactate). The calculated value of the MGR depends on whether growth-death data or only growth data are used in the fitting procedure. The quasi-chemical kinetics model is also exploited for use with the novel food processing technology of high-pressure processing. The high-pressure inactivation kinetics of E. coli are explored in a model food system over the pressure (P) range of 207-345 MPa (30,000-50,000 psi) and the temperature (T) range of 30-50 degrees C. In relatively low combinations of P and T, the inactivation curves are non-linear and exhibit a shoulder prior to a more rapid rate of microbial destruction. In the higher P, T regime, the inactivation plots tend to be linear. In all cases, the quasi-chemical model successfully fit the linear and curvi-linear inactivation plots for E. coli in model food systems. The experimental data and the quasi-chemical mathematical model described herein are candidates for inclusion in ComBase, the developing database that combines data and models from the USDA Pathogen Modeling Program and the UK Food MicroModel.

Bacteria↗
PubMed1995

Effect of changes in processing to improve hygiene control on contamination of poultry carcasses with campylobacter.

Examination of neck skin and caecal samples taken at a commercial processing plant from 15 randomly chosen poultry flocks showed that all flocks were contaminated initially with thermophilic Campylobacter spp., even in the apparent absence of caecal carriage. During processing, numbers of campylobacter on skin samples were reduced by between 10 and 1000-fold. To improve hygiene control generally, chlorinated-water sprays were used to limit microbial contamination on equipment and working surfaces. In addition, chlorine concentrations in process water were increased and any unnecessary carcass contact surfaces in the processing plant were removed. When comparing flocks before and after the changes, it was found that numbers of campylobacter on packaged carcasses were significantly lower after the changes had been made (P 0.001). In practice, however, the reduction would be likely to have little impact on consumer exposure to campylobacter infection.

Animals↗
PubMed2001

Clinical assay of N-duopropenide alcohol solution on hand application in newborn and pediatric intensive care units: control of an outbreak of multiresistant Klebsiella pneumoniae in a newborn intensive care unit with this measure.

Outbreaks of gram-negative colonization (generally by antibiotic-resistant enterobacteria) are common in newborn intensive care units (NICUs), and control methods are not always effective. We studied the effectiveness of an alcohol solution of N-duopropenide (NDP) in vivo (germicidal effect on flora of teams in the NICU and the pediatric intensive care unit vs handwashing with nonantiseptic soap) and its effect on the control of a multiresistant (MR) Klebsiella pneumoniae outbreak in our NICU that had persisted for 13 months, despite the use of classic control measures. For educational purposes, we also performed 4 prevalence studies of microbial hand flora in NICU staff (two before and two after introducing NDP). The alcohol solution of NDP was highly germicidal in vivo, destroying microorganisms better than classic handwashing on the hands of 69 health care staff of our NICU and PICU. The flora in both units was reduced from an average of 63% to an average of 95%. Application of this disinfectant to the hands of health care workers after handling newborns helped to eliminate the MR Klebsiella strain in our NICU, (relative risk compared with the period preceding use of the disinfectant: 8.6, with 95% confidence intervals, 4.8-145.5). Four prevalence studies of hand microbial contamination, before and after NDP introduction in the NICU, showed a significant reduction of enterobacteriaceae, mainly MR K pneumoniae, in health care workers. In conclusion, NDP in alcohol was very effective in vivo. It proved to be a useful complementary measure to handwashing and reduced exogenous microorganism transmission in a unit with a heavy patient-care workload.

2-Propanol↗
PubMed2000

Periodontopathic bacteria in children with Down syndrome.

BACKGROUND: It is widely known that individuals with Down syndrome (DS) often develop severe early-onset periodontal diseases. In this study, we examined the prevalence of periodontopathic bacteria in DS children to determine if specific pathogens are acquired in their childhood. METHODS: The subjects were 60 DS children (2 to 13 years old, 5 in each age bracket) and 60 age-matched controls. Ten pathogens, Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Bacteroides forsythus, Treponema denticola, Prevotella intermedia, P nigrescens, Capnocytophaga ochracea, C. sputigena, Campyrobacter rectus, and Eikenella corrodens were surveyed in subgingival plaque samples using a polymerase chain reaction. Periodontal status was evaluated by probing depth, bleeding on probing, and gingival index. RESULTS: No significant difference in periodontal status was observed between the DS and control groups, however, all of the pathogens were detected with greater frequency in the DS children. B. forsythus, T. denticola, P. nigrescens, and C. rectus were significantly prevalent throughout all age brackets of the DS children (P <0.01 or 0.05). The occurrence of P. gingivalis was also significant in the DS subjects over 5 years old. A cluster analysis of the microbial profiles of the DS subjects showed that gingivitis severity was associated with increased varieties of the harboring pathogens and the distribution of P. gingivalis. CONCLUSIONS: These results suggest that various periodontopathogens can colonize in the very early childhood of DS patients and maturation of subgingival components, including P. gingivalis, plays an important role in the initiation of gingival inflammation.

Adolescent↗
PubMed1998

Postprocess contamination of flexible pouches challenged by in situ immersion biotest.

Packages were evaluated for leaks by determining microbial penetration through microchannels as a function of test organism concentration, location in a retort, and microchannel diameter and length. A flexible pouch was used in an in situ immersion biotest coupled with a state-of-the-art retort. Microchannel diameters of 10 to 661 microm with 3- and 6-mm lengths were created by placing tungsten wires in vacuum heat-sealed flexible pouches. After removing the wires, these pouches were subsequently heat processed under pressure. They were then biotested in cooling water containing 10(3) and 10(6) CFU of motile Enterobacter aerogenes per ml for 30 min and were dried immediately after manual unloading. After incubation at 37 degrees C for 3 days, they were visually examined for contamination. The high-temperature retorting process was shown to decrease microchannel diameters by an average of 20%. Generally, the smaller the microchannel diameter, the greater the percent shrinkage. Statistical analysis of the biotesting data showed that microchannel diameter and length had strong effects on microbial penetration (P < 0.01). Microbial concentration had a borderline significant effect (P < 0.05), but the effect of package location in the retort was not significant. At conservative conditions, such as a 3-mm microchannel length and a cooling water contamination level of 10(6) CFU/ml, the selected microorganism can penetrate microchannels with diameters as small as 7 microm. However, the minimum microchannel diameter for penetration could be as large as 46 microm at practical conditions of 6-mm microchannel length and contamination levels of 10(3) CFU/ml.

Colony Count, Microbial↗
PubMed2003

Antimicrobial efficacy of a silver-zeolite matrix coating on stainless steel.

A silver- and zinc-containing zeolite matrix (AgION) used as a coating for stainless steel was tested for antimicrobial efficacy against Escherichia coli 25922, Staphylococcus aureus 25923, Pseudomonas aeruginosa 27853, and Listeria monocytogenes 7644. Assays were performed on flat coupon surfaces and in formed steel cups. AgION reduced microbial colony-forming units when compared to uncoated steel surfaces under all conditions tested. Percent reductions ranged from 84.536 to 99.999 after 4 h exposure, and from 99.992 to 100 after 24 h in all cases. The durability of the coatings declined most markedly when the coating had been applied with a wet process and scrubbed between uses with a test tube brush. Powder-coated surfaces cleaned with a towel retained a high degree of activity after five cycles of use.

Anti-Bacterial Agents↗
PubMed1991

The effect of handling procedures on microbial contamination of enteral feeds--a comparison of the use of sterile vs non-sterile gloves.

The use of non-sterile disposable gloves to reduce the level of microbial contamination introduced into enteral feeds during the assembly of the feeding systems was investigated. No contamination was detected in any of the feed samples collected from the systems assembled wearing non-sterile gloves. The number of microorganisms transferred to the surface of agar plates used for fingerprint cultures was reduced from an average of 43-54 colony forming units (cfu) per plate for volunteers with bare hands to less than 1 cfu when they wore non-sterile gloves. No contamination was detected on plates touched by volunteers wearing sterile gloves.

Adolescent↗
PubMed2005

Two-dimensional distribution of microbial activity and flow patterns within naturally fractured chalk.

The two-dimensional distribution of flow patterns and their dynamic change due to microbial activity were investigated in naturally fractured chalk cores. Long-term biodegradation experiments were conducted in two cores ( approximately 20 cm diameter, 31 and 44 cm long), intersected by a natural fracture. 2,4,6-tribromophenol (TBP) was used as a model contaminant and as the sole carbon source for aerobic microbial activity. The transmissivity of the fractures was continuously reduced due to biomass accumulation in the fracture concurrent with TBP biodegradation. From multi-tracer experiments conducted prior to and following the microbial activity, it was found that biomass accumulation causes redistribution of the preferential flow channels. Zones of slow flow near the fracture inlet were clogged, thus further diverting the flow through zones of fast flow, which were also partially clogged. Quantitative evaluation of biodegradation and bacterial counts supported the results of the multi-tracer tests, indicating that most of the bacterial activity occurs close to the inlet. The changing flow patterns, which control the nutrient supply, resulted in variations in the concentrations of the chemical constituents (TBP, bromide and oxygen), used as indicators of biodegradation.

Aerobiosis↗
PubMed2004

A comparison of decontamination methods used for dental burs.

OBJECTIVES: This study investigated the bacterial and fungal contamination of used dental burs. A novel assay system for comparison of efficacy of pre-sterilisation cleaning techniques for dental burs was used to evaluate manual scrubbing, enzymic agents and washer-disinfectors. METHODS: Thirty dental burs contaminated during cavity preparation were analysed for micro-biological total viable counts and species of bacteria and fungi present. To simulate clinically contaminated burs, a culture of Streptococcus sanguis NCTC 7863 was used to inoculate unused dental burs, alone and combined with blood, saliva or a mixture of blood and saliva. Contaminated burs were subjected to six pre-sterilisation cleaning techniques and the log reduction in contamination achieved by each method was assessed. RESULTS: The microbial count from used dental burs ranged from 0 to 6.92 x 10(4) CFU ml(-1). Many potentially pathogenic species were identified. The decontamination assay demonstrated that autoclaving alone was not sufficient to sterilise dental burs. Manual scrubbing in air was less efficacious than manual scrubbing under water (p<0.001). The most effective method of pre-sterilisation cleaning for dental burs was a washer-disinfector. CONCLUSIONS: Enzymic agents are suitable for soaking contaminated dental burs immediately after use. Washer-disinfectors are recommended as the method of choice for pre-sterilisation cleaning of contaminated dental burs.

Air↗
PubMed1988

Analytical and physiological variability of salivary microbial counts.

Quantitation of mutans streptococci (MS) and Lactobacillus has been proposed as a method for the identification of patients at high risk for dental caries. The purpose of the present study was to investigate the analytical and physiological variability of this procedure. Variability due to specimen collection and processing was investigated by repeated sampling studies. Sample stability was investigated over storage periods of up to 72 hr at 5 degrees C, room temperature, and 37 degrees C. Physiological variability was investigated by performance of serial analyses on ten individuals, who collected six samples at intervals on a single day, and rising and noon samples on ten subsequent days. Sample collection, rather than sample processing, was found to be the major factor determining the imprecision of salivary microbial analysis in the majority of cases. However, individual subjects varied considerably in the consistency with which they provided saliva samples. Imprecision due to sample processing was relatively small, with coefficients of variations of 2.3% for MS counts and 2.1% for Lactobacillus counts. Samples were generally stable over a wide temperature range for at least 72 hours, although there was some loss of viability of lactobacilli on prolonged storage at room temperature or 37 degrees C in one experiment. Rising samples yielded higher counts than samples collected after breakfast and toothbrushing. Day-to-day variability was considerable, with 95% confidence limits exceeding 1 log in 28% of data sets for MS count and 39% of data sets for Lactobacillus.

Circadian Rhythm↗
PubMed1994

Effect of dietary fiber on microbial activity and microbial gas production in various regions of the gastrointestinal tract of pigs.

The microbial activity, composition of the gas phase, and gas production rates in the gastrointestinal tract of pigs fed either a low- or a high-fiber diet were investigated. Dense populations of culturable anaerobic bacteria, high ATP concentrations, and high adenylate energy charges were found for the last third of the small intestine, indicating that substantial microbial activity takes place in that portion of the gut. The highest microbial activity (highest bacterium counts, highest ATP concentration, high adenylate energy charge, and low pH) was found in the cecum and proximal colon. Greater microbial activity was found in the stomach and all segments of the hindgut in the pigs fed the high-fiber diet than in the pigs fed the low-fiber diet. Considerable amounts of O2 were found in the stomach (around 5%), while the content of O2 in gas samples taken from all other parts of the gastrointestinal tract was < 1%. The highest concentrations and highest production rates for H2 were found in the last third of the small intestine. No methane could be detected in the stomach or the small intestine. The rate of production and concentration of methane in the cecum and the proximal colon were low, followed by a steady increase in the successive segments of the hindgut. A very good correlation between in vivo and in vitro measurements of methane production was found. The amount of CH4 produced by pigs fed the low-fiber diet was 1.4 liters/day per animal. Substantially larger amounts of CH4 were produced by pigs fed the high-fiber diet (12.5 liters/day)(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Triphosphate↗
PubMed2004

Household cleaning and surface disinfection: new insights and strategies.

Recently, new insights into the persistence of pathogens, their transfer from inanimate surfaces to humans and the risk of contamination and dissemination of pathogens by detergents have been gained. Furthermore, new experimental data on the interruption of chains of infection by disinfectants as well as results of outbreak-control studies are now available. Hence it has become necessary to reassess the potential benefits using disinfectants to prevent and control nosocomial infections. Based on the new findings and in view of the increasing incidence of nosocomial infections and antibiotic resistances, the German Robert-Koch-Institut has issued completely revised recommendations on Household Cleaning and Surface Disinfection. With respect to these recommendations we developed a new test method, which allows comparison of the efficacy of disinfection in reducing the microbial loads and their dissemination with that of cleaning procedures under practical conditions. In a multi-factor approach, mechanical properties (wet mop technique), utensils (different mop materials) and active agents (disinfectant, detergent) were taken into consideration. We found that under the given conditions, dissemination of the test organism Staphylococcus aureus did not take place when using aldehydes and peroxides, it did take place, however, when water, surfactants, and the disinfectants glycol derivatives, quaternary ammonium compounds and alkylamines were used.

Colony Count, Microbial↗
PubMed2001

Formation of higher plant component microbial community in closed ecological system.

Closed ecological systems (CES) place at the disposal of a researcher unique possibilities to study the role of microbial communities in individual components and of the entire system. The microbial community of the higher plant component has been found to form depending on specific conditions of the closed ecosystem: length of time the solution is reused, introduction of intrasystem waste water into the nutrient medium, effect of other component of the system, and system closure in terms of gas exchange. The higher plant component formed its own microbial complex different from that formed prior to closure. The microbial complex of vegetable polyculture is more diverse and stable than the monoculture of wheat. The composition of the components' microflora changed, species diversity decreased, individual species of bacteria and fungi whose numbers were not so great before the closure prevailed. Special attention should be paid to phytopathogenic and conditionally pathogenic species of microorganisms potentially hazardous to man or plants and the least controlled in CES. This situation can endanger creation of CES and make conjectural existence of preplanned components, man, specifically, and consequently, of CES as it is.

Brassicaceae↗
PubMed2003

Ophthalmic delivery of ciprofloxacin hydrochloride from different polymer formulations: in vitro and in vivo studies.

Reservoir-type ocular inserts were fabricated using sodium alginate containing ciprofloxacin hydrochloride as the core (drug reservoir) that was sandwiched between the Eudragit and/or polyvinylacetate films. Ocular inserts were packaged in aluminium foil and sterilized by gamma radiation. These were tested for sterility as per British Pharmacopoeia (BP). Ocular inserts were evaluated for in vitro release rate studies, microbial efficacy, in vivo release studies, efficacy against induced bacterial conjunctivitis in rabbit's eyes, concentration in the aqueous humor, and stability studies as per the International Conference on Harmonization (ICH) guidelines. Ocular inserts passed the test for sterility. They showed zero-order release of the drug in the in vitro and in vivo release studies over a period of 120 hr. The drug was found to be active against selected microorganisms as was proved by microbial efficacy studies. A high correlation coefficient was found between in vitro and in vivo release rate studies. Better improvement was observed in artificially induced bacterial conjunctivitis in rabbit's eyes, compared with marketed eye drops and placebo. Drug concentration in the aqueous humor was found above Minimum Inhibitory Concentration (MIC-90) against selected microorganisms. Shelf-life of the product was found to be more than 2 years.

Administration, Topical↗
PubMed2003

Release of Ni and Co by microbial activity in New Caledonian ultramafic soils.

A high positive correlation was found between extractable Ni and Co contents and microbial activity of 40 ultramafic soil samples from New Caledonia, suggesting a possible role of microorganisms in the release of these two metals. A saprolite (ultramafic subsoil) and a hypermagnesian brown soil were incubated 9 months in different conditions. Ni and Co release, measured by their extractability, occurred without reduction of soil pH but did not occur when the native microflora was eliminated by heat treatment. However, when autoclaved soil was re-inoculated with a pinch of the same nonheated soil, the release of metals was recorded. The concentrations of extractable Ni and Co were much higher in soils amended with organic compounds in which microbial activity was enhanced, but only if the soil was not heat treated. The presence of Grevillea exul, a metal-tolerant plant, stimulated the metal release process, but the stimulation was less effective than it was in the compost-amended soil without plant. The influence of the plant in extractable Ni and Co contents in this amended soil was not significant. The release of the two metals therefore seemed to be induced by the activity of specialized organotrophic microorganisms.

Bacterial Physiological Phenomena↗
PubMed2004

Evidence of pathogenic microbes in the International Space Station drinking water: reason for concern?

Molecular analyses were carried out on four preflight and six postflight International Space Station (ISS)-associated potable water samples at various stages of purification, storage, and transport, to ascertain their associated microbial diversities and overall microbial burdens. Following DNA extraction, PCR amplification, and molecular cloning procedures, rDNA sequences closely related to pathogenic species of Acidovorax, Afipia, Brevundimonas, Propionibacterium, Serratia, and others were recovered in varying abundance. Retrieval of sequences arising from the iodine (biocide)-reducing Delftia acidovorans in postflight waters is also of concern. Total microbial burdens of ISS potable waters were derived from data generated by an ATP-based enumeration procedure, with results ranging from 0 to 4.9 x 10(4) cells/ml. Regardless of innate biases in sample collection and analysis, such circumstantial evidence for the presence of viable, intact pathogenic cells should not be taken lightly. Implementation of new cultivation approaches and/or viability-based assays are requisite to confirm such an occurrence.

Anti-Bacterial Agents↗
PubMed2002

Influence of storage on chemical, microbial and consumer acceptability of a milk-like product made from melon seeds.

The storage stability of melon milk at room (30 +/- 2 degrees C) and refrigeration (10 +/- 2 degrees C) temperatures was determined by analyzing changes in the chemical, microbial and sensory properties of the milk stored for 7 days. The results showed that at both storage temperatures, soluble solids and pH of the milk decreased while titratable acidity increased with storage. The standard plate counts increased appreciably while coliforms were absent in the milk with storage at both storage temperatures. The overall acceptability score of the melon milk dropped during storage, the drop being faster at 30 +/- 2 degrees C than at 10 +/- 2 degrees C. The milk samples stored at 30 +/- 2 degrees C and 10 +/- 2 degrees C were acceptable only within one and three days, respectively; thereafter, they were unacceptable.

Colony Count, Microbial↗