George M. Kalmanson

In Vitro Activity of Ampicillin or Vancomycin Combined with Gentamicin or Streptomycin Against Enterococci

Minimum inhibitory and bactericidal concentrations of four antibiotics and their combinations were determined for 38 strains of enterococci by a microtitration tube dilution technique. The drugs were ampicillin, vancomycin, gentamicin, and streptomycin; the combinations were ampicillin-gentamicin, ampicillin-streptomycin, vancomycin-gentamicin, and vancomycin-streptomycin. At achievable serum concentrations, ampicillin alone killed 60% of strains, whereas combination with streptomycin increased this to 90% and with gentamicin to 100%. Vancomycin alone showed striking inhibitory activity, but very poor bactericidal activity at achievable concentrations. Combination with one of the aminoglycosides increased the bactericidal activity substantially. When combined with ampicillin, gentamicin was both more active and showed synergistic bactericidal activity significantly more often (P < 0.01) than streptomycin.

Leukocyte phagocytosis and serum bactericidal activity in chronic renal failure.

Polymorphonuclear leukocytes from patients with chronic renal failure had an impaired ability to engulf Bacillus subtills when compared with polymorphs from normal subjects. Serum from uremic patients killed Escherichia coli and two strains of Staphylo-coccus aureus loss readily than normal serum. An unexpected finding was the increased killing of B. subtilis by scrum from patients with chronic renal failure. L-forms of Strepto-coccus faecalis were equally susceptible to uremic and normal serum. Serum complement levels were not significantly different from those of normal persons. The findings are consistent with the increased susceptibility of uremic subjects to infections.

Variables in demonstrating methicillin tolerance in Staphylococcus aureus strains.

Certain technical considerations which affected the status of methicillin tolerance in Staphylococcus aureus strains were studied. Methods which consistently demonstrated tolerance or intolerance of a given strain were avoidance of inoculum splashing, use of stationary-phase inoculum, 24-h tube incubation, and minimization of antibiotic carry-over. These studies suggested a need for the establishment of a standardized reference for the determination of tolerance.

Mycoplasmal Arthritis of the Mouse: Development of Cellular Hypersensitivity to Normal Synovial Tissue

Summary Cellular hypersensitivity to normal mouse synovial tissue was found in arthritic mice infected by iv injection of Mycoplasma pulmonis but not in uninfected normal mice. Hypersensitivity was determined by inhibition of migration of peritoneal macrophages in the presence of an antigen made from normal mouse synovium. Since, in a previous study, no correlation was found between the presence of mycoplasmas in arthritic joints and the extent of arthritis, this data suggests that both microbiological and immunological mechanisms are involved in the pathogenesis of the disease. Addendum. An additional experiment was performed to test the specificity of the reaction to synovial antigen. Cells from 12 mice infected 14 to 35 weeks and 12 age-matched controls were incubated in the presence or absence of an antigen prepared from normal mouse kidney by the method outlined for synovial antigen. Using 12.5 μg/ml (the highest concentration not affecting cells from normal mice) the migration area from the infected animals with antigen was 65.47 ± 7.97 cm2; without antigen, 60.49 ± 5.58 cm2; controls with antigen 40.74 ± 4.25 cm2; without antigen 38.69 ± 3.05 cm2. Thus no significant effect was seen in either infected or control animals. We thank Gussie Goldberg, Jessie Hardin, Mike Y. Kubota, Judy Noel, and Melvaline Oliver for their excellent technical assistance.

Pyelonephritis. III. Observations on the association between chronic pyelonephritis and hypertension in the rat.

Summary Chronic, progressive, non-obstructed, enterococcal pyelonephritis in the rat is not associated with hypertension. It is suggested that this may be related to the absence of significant arteriolar nephrosclerosis.

PYELONEPHRITIS. V. ROLE OF SERUM BACTERICIDAL ACTIVITY AND ANTIBODY IN ACUTE PYELONEPHRITIS IN THE RABBIT.

Summary Intravenous injection of rabbits with Str. faecalis produced an acute pyelonephritis which spontaneously resolved in a few weeks. This infection was accompanied by vigorous antibacterial antibody (agglutinating and hemagglutinating) production which was not associated with increase in serum bactericidal activity as tested. There appeared to be no correlation between individual rabbit pre-infection serum bactericidal activity and the quantitative bacteriological findings in the kidney. The difference between the outcome of infection in the rabbit and rat has not been explained by the immunological studies performed.

Relation Between Bacteriocin Production and Virulence of Streptococcus faecalis var. liquefaciens

Summary Eight strains of Streptococcus faecalis var. liquefaciens were classified as bacteriocin producing or nonproducing on the basis of their effect on microbial L-forms. Four strains produced bacteriocin, and four did not. There was a significant association between bacteriocin production and ability to produce hematogenous pyelonephritis in the rat.

Effect of renal physicochemical milieu on stimulation of human lymphocytes by phytohemagglutinin.

The effect of changes in certain physicochemical parameters, analogous to those occurring in the kidney, on stimulation of normal human lymphocytes by phytohemagglutinin was studied. Increase in osmolality by sucrose or urea, and increases in concentration of sodium, potassium and calcium all significantly inhibited stimulation while magnesium did not. Lowering pH to 6.8 and 6.5 inhibited stimulation. Raising the pH to 8.0 had no effect bu at pH 8.4 stimulation was decreased. The effect was largely but not entirely due to decrease in viability.

Pigment Formation in L-forms of Serratia marcescens

SUMMARY: L-forms of Serratia marcescens were produced and serially transferred in osmotically stabilized agar with penicillin. The bacterial form was pigmented, while the L-form colony was not. Lack of colour in the L-form colony was not due to pigment diffusion into the agar; an extract of agar with L-form growth did not show an absorption spectrum for prodigiosin.

PYELONEPHRITIS. IV. ROLE OF SERUM BACTERICIDAL ACTIVITY AND ANTIBODY IN CHRONIC ENTEROCOCCAL PYELONEPHRITIS IN THE RAT.

Summary Pyelonephritis produced in rats by intravenous inoculation of Str. faecalis becomes established in the presence of normal serum bactericidal activity against the infecting organism. The infection persists throughout the life of the rat despite the eventual appearance of circulating antibacterial antibodies. This finding may be partially explained by the fact that these antibodies do not enhance normal serum bactericidal activity as tested.