Presence Of Broth Research Articles

Impact of the Epithelial Lining Fluid Milieu on Amikacin Pharmacodynamics Against Pseudomonas aeruginosa.

BackgroundEven though nebulised administration of amikacin can achieve high epithelial lining fluid concentrations, this has not translated into improved patient outcomes in clinical trials. One possible reason is that the cellular and chemical composition of the epithelial lining fluid may inhibit amikacin-mediated bacterial killing.ObjectiveThe objective of this study was to identify whether the epithelial lining fluid components inhibit amikacin-mediated bacterial killing.MethodsTwo amikacin-susceptible (minimum inhibitory concentrations of 2 and 8 mg/L) Pseudomonas aeruginosa isolates were exposed in vitro to amikacin concentrations up to 976 mg/L in the presence of an acidic pH, mucin and/or surfactant as a means of simulating the epithelial lining fluid, the site of bacterial infection in pneumonia. Pharmacodynamic modelling was used to describe associations between amikacin concentrations, bacterial killing and emergence of resistance.ResultsIn the presence of broth alone, there was rapid and extensive (> 6 − log10) bacterial killing, with emergence of resistance identified in amikacin concentrations < 976 mg/L. In contrast, the rate and extent of bacterial killing was reduced (≤ 5 − log10) when exposed to an acidic pH and mucin. Surfactant did not appreciably impact the bacterial killing or resistance emergence when compared with broth alone for either isolate. The combination of mucin and an acidic pH further reduced the rate of bacterial killing, with the maximal bacterial killing occurring 24 h following initial exposure compared with approximately 4–8 h for either mucin or an acidic pH alone.ConclusionsOur findings indicate that simulating the epithelial lining fluid antagonises amikacin-mediated killing of P. aeruginosa, even at the high concentrations achieved following nebulised administration.Supplementary InformationThe online version contains supplementary material available at 10.1007/s40268-021-00344-5.

The Value of Adsorbents for Detecting Survival in Bacterial Populations Exposed to Phenols

Summary The inclusion of 0·1 per cent, of activated charcoal or 0·03 per cent. of ferric chloride in subculture media had no consistent influence on the extinction times of Bact. coli exposed to 1 per cent, phenol, but the overall responses in experiments made with several batches of media were positive. On the whole, individual batches of medium consistently gave the same kind of response, positive or null. Activated charcoal (0·1 per cent.) adsorbed about 80 per cent, of the phenol from solution in water at a concentration of 0·005 per cent. In the presence of broth much less was adsorbed; Norit adsorbed only about 9 per cent, and Darco G 60 about 25 per cent. The ferric chloride-nutrient broth precipitate did not adsorb phenol from either water or broth. 5 In the concentration range 0·001 to 0·020 per cent., phenol in the subculture medium did not appear to influence the extinction times of bacterial populations exposed to that substance.

Transfer delay and chromosome withdrawal during conjugation inEscherichia coli

Chromosome transfer has been studied in mating pairs formed during a 5-minute interval, under conditions that prevent the formation of new pairs. It has been found that, despite restriction of the period of effective contact formation, there is a considerable spread in the time at which transfer is initiated in the different mating pairs. In some pairs there is a delay of as much as 15 minutes before transfer commences.The presence of broth in the medium in which transfer takes place leads to a marked reduction in the stability of pairs involving some Hfr strains, but has little or no effect on pairs involving others. The action of broth can be ascribed to the effect of a complete mixture of amino-acids on the metabolic activity of the donor cells.A segment of chromosome which has penetrated from the Hfr into the F−cell may be subsequently withdrawn. Withdrawal may take place in more than half of the mating pairs, and probably occurs at the time when the donor and recipient cells separate. It is prevented if the chromosome breaks when conjugation is interrupted.

A Comparison of the Efficiency of Phenol, Liquor Cresolis, Formaldehyde, Sodium Hypochlorite and Sodium Hydroxide Against Eberthella Typhi at Various Temperatures

The influence of temperature, dilution and organic matter on the germicidal powers of chemical agents frequently is overlooked or minimized and the relative importance of these factors is not fully appreciated. While ample data have been presented to show the efficiencies of the common disinfectants against Eberthella typhi in broth at 20 C, little information of their comparative values under conditions approximating actual disinfection has been presented. A study was therefore made to determine the concentrations of phenol, liquor cresolis, formaldehyde, sodium hypochlorite and sodium hydroxide necessary to kill E. typhi at 2 C, 20 C. and 40 C. in the presence of a heavy suspension of human feces, as well as in the presence of broth.

THE SPECIFIC POLYSACCHARIDES OF TYPES I, II, AND III PNEUMOCOCCUS

1. The thermolability of the specific polysaccharides of Types I, II, and III pneumococcus has been shown by three independent methods: (a) diminution of the viscosity of solutions on heating; (b) decrease in the amount of antibody precipitated from homologous rabbit antisera; and (c) increased tendency (S III) to pass through a collodion membrane. 2. These effects may be explained most simply as a partial depolymerization under the influence of heat. In air, particularly in the presence of broth, oxidation also appears to be involved. 3. Improved and simpler methods of preparation based on these findings, are given for S I, S II, and S III. The resulting products precipitate more anti-S from homologous rabbit antisera than do the earlier preparations. 4. The methyl glycoside of methyl galacturonate has been isolated from the hydrolytic products of S I, and evidence of the ultimate structural unit obtained.