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Biomedical subjects

V Lorian

Publications and source records attributed to V Lorian.

106 records · Page 6Linked to original sources
PubMed1966

Direct cord reading medium for isolation of mycobacteria.

A study of growth and colony morphology of mycobacteria was performed on 7H10 medium and compared with the same medium to which WR 1339 was added. Collection strains of human, bovine, and atypical mycobacteria, in addition to 1,199 sputa, were planted on both media. The results showed that WR 1339 modifies the growth and colony morphology of human, bovine, atypical group I, and, to a lesser degree, atypical groups II, III, and IV mycobacteria. The great majority of human and bovine strains exhibit definite cords when examined at a magnification of 100 times. The colonies are larger when WR 1339 is added, especially if there is a small number of colonies. The addition of WR 1339 spreads the growth on the surface of the agar, producing a thin but larger colony as compared with 7H10 medium alone on which the colonies grow more vertically, thus producing thick but smaller colonies. WR 1339 spreads the growth, producing thin and transparent colonies where the cords are oriented in uniplane and easily visible directly on the isolation media. Half of the positive sputum cultures were easily identified at 12 days. The presence of typical cords permits a quick screening diagnosis of species directly on the isolation media and, in most instances, elimination of the possibility of atypical or contaminating colonies.

Culture Media↗
PubMedDate not supplied

Effect of serum and blood on Enterobacteriaceae grown in the presence of subminimal inhibitory concentrations of ampicillin and mecillinam.

Bacteria from the strains of five species of Enterobacteriaceae grown in the presence of subminimal inhibitory concentrations of ampicillin or mecillinam formed into filamentous or round cells. These filamentous and round cells as well as normal control bacteria were incubated with either fresh human serum or blood, the bactericidal effects of which were then determined. In most cases, the bactericidal effect of either serum or blood on filamentous or round cells was less than the effect on control cells. In some cases, the effect on these drug-exposed cells was similar to that on control cells, but in no instance was the effect greater for the drug-exposed cells than for the control cells. However, in all cases in which the bactericidal effect of either serum or blood on the control cells was greater than or equal to 99%, the bactericidal effect on the drug-exposed cells was close to 90%. Although drug-exposed cells were not much more resistant to the bactericidal effect of serum or blood than were normal bacteria, they clearly were not more susceptible to these effects.

Amdinocillin↗
PubMedDate not supplied

Effect of rifampin and oxacillin on the ultrastructure and growth of Staphylococcus aureus.

The minimal inhibitory concentrations (MICs) of rifampin for 12 strains of Staphylococcus aureus ranged from 0.005 microgram/ml to 0.02 microgram/ml, and the minimal antibiotic concentrations (i.e., those that inhibited growth by 90% in comparison with control values) ranged from one-fifth to one-half the MICs. Rifampin alone produced a 1-log (90%) decrease in the staphylococcal population after incubation for 6.5 hr, and the inhibitory effect after removal of the antibiotic lasted for 5 hr. Regardless of whether rifampin was used simultaneously with, before, or after exposure to oxacillin, the latter drug partially or totally prevented the overgrowth of rifampin-resistant staphylococci. The use of this combination in therapy is therefore justified. Staphylococci exposed to rifampin at concentrations equal to three or 20 times the MIC developed a cell wall that was four times thicker than normal and had a peripheral undulated dense layer. The cross walls were also two to 10 times thicker than normal but had a normal central dense zone. Exposure of staphylococci to oxacillin produced large cells with multiple cross walls that underwent autolysis when the organisms were transferred to drug-free medium. When exposure to oxacillin was preceded by exposure to rifampin, cells did not become enlarged. When the large cells produced by oxacillin were transferred to medium containing rifampin, the cross walls did not lyse.

Drug Synergism↗