Penicillin: effect on sodium and potassium transport in bacterial and protoplast forms of Sterptococcus faecalis.

Streptococcus faecalis, incubated in osmotically stabiliz medium in the presence of 1000 units of penicillin per milliliter, accumulated rather than extruded sodium; they accumulated much less potassium than control cells did. These changes were not due to binding of sodium by cell-wall fragments of cells treated with penicillin. Because penicillin had no effect on cation concentrations in stable protoplasts and nongrowing bacterial cells, this effect appeared to be related to the production of the penicillin-induced lesions of the cell wall.

Chemotactic activity of L-forms and mycoplasma.

L-forms of Streptococcus faecalis, Escherichia coli and Proteus mirabilis showed significantly less chemotactic activity for normal human leucocytes than did parent bacterial forms which were strongly chemotactic. Mycoplasma pneumoniae and Mycoplasma hominis did not demonstrate chemotactic activity.

Pyelonephritis XI. Effect of Growth Phase of Streptococcus faecalis on Serum Susceptibility and Virulence.

Rapidly growing Streptococcus faecalis was found to be markedly susceptible to the bactericidal activity of normal rat and rabbit sera, whereas stationary-phase organisms were resistant. In contrast, human serum killed neither phase organism. Further, human serum was found to interfere with killing by rabbit serum. The serosusceptible, rapidly growing organisms were less virulent than the seroresistant, stationary-phase organisms. This was tested by production of pyelonephritis in the rat after intravenous inoculation of the organism. Renal bacterial content over a period of 4 weeks was significantly less in those animals which had received rapidly growing organisms.

Human diseases associated with mycoplasms. With an appendix on simple culture techniques.

The mycoplasmas (formerly called pleuropneumonia-like organisms, or pplo) are a group of pleomorphic micro-organisms characterized by lack of cell wall and ability to form colonies on agar resembling tiny fried eggs. They have been recognized as pathogens of lower mammals since 1898. Of the more than 40 known veterinary species, many are pathogens, commonly causing pneumonia, arthritis or arteritis. Of the mycoplasmas found in man, Mycoplasma pneumoniae is the only well established human pathogen. It is responsible for a variety of respiratory syndromes, of which the most frequently recognized is cold agglutinin-positive atypical pneumonia. Hematologic, neurologic and dermatologic complications of this infection have been noted. M. hominis has been implicated as a causative factor in various febrile complications of pregnancy, such as septic abortion and amnionitis. T-strain mycoplasmas are ubiquitous in the human genitourinary tract, but attempts to link their presence to disease have thus far been unsuccessful. Mycoplasmas also have been associated with neoplastic disease and with rheumatoid arthritis. The validity of these latter findings is unclear, and additional study is needed.

Pyelonephritis. 18. Effect of treatment on the pathology of enterococcal pyelonephritis in the rat.

The effect of antimicrobial therapy on the histopathologic progression of experimental hematogenous pyelonephritis induced in rats by Streptococcus faecalis was studied. Treatment sufficient to render the renal parenchyma sterile strikingly decreased the incidence and severity of calyceal lesions, delayed the progression of papillary lesions but had little effect on the severity of cortical interstitial and tubular alterations. L-forms could not be demonstrated to participate in the pathogenesis of these lesions. Kanamycin had an independent nephrotoxic effect which complicated interpretation of the effect of therapy in animals receiving this agent.

Synergism of polymyxin and sulfonamides in L-forms of Staphylococcus aureus and Proteus mirabilis.

Earlier workers suggested that synergism of polymyxin and sulfonamides occurred because sulfonamides produced changes in the cell wall which permitted the more ready access of polymyxin. We tested this hypothesis by using L-forms, which lack cell wall. The demonstration that synergism of polymyxin and sulfonamides occurs in L-forms of Proteus mirabilis and Staphylococcus aureus suggested that the synergism is a result of some mechanism other than alterations of the cell wall.

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.

Klebsiella L-forms: effect of growth as L-form on virulence of reverted Klebsiella pneumoniae.

A strain of Klebsiella pneumoniae virulent for mice was serially passaged in vitro as a penicillin-induced L-form. Periodically, the L-form was reverted to the bacterial form by removal of penicillin, and the revertant was tested for virulence. Virulence was gradually reduced, and after 109 passages the revertant was totally avirulent. Virulence was not restored by 40 passages of the revertant through mouse peritoneum. The revertant grew less vigorously and did not infect mice when inoculated subcutaneously; in contrast, the parental form was found in all tissues examined. After phagocytosis in vitro or in vivo, the revertant survived but did not increase in numbers, whereas the parental form did increase in numbers. The revertant had a much smaller capsule than did the parental form. Immunization with the live revertant resulted in type-specific protection against infection with the parental form.

Fatty acid composition of L-forms of Streptococcus faecalis cultured at different osmolalities.

The fatty acid composition of the membranes of three different penicillin-produced L-forms of Streptococcus faecalis was determined: (i) a stable (nonreverting) L-form (T(53)) cultured in brain heart infusion (BHI) with 0.5 M sucrose; (ii) a stable L-form (T(531)) cultured in BHI without sucrose; and (iii) an unstable L-form (T(9)) cultured in BHI with 0.5 M sucrose and 1,000 U of penicillin per ml. L-forms were obtained by centrifugation and lysed by washing in 1 mM tris(hydroxymethyl)aminomethane-hydrochloride buffer. The parent S. faecalis was also cultured in BHI and BHI containing 0.5 M sucrose, and washed with buffer. The fatty acid composition of L-forms of S. faecalis cultured in BHI without sucrose (370 mosmol) had higher C(18:1) and lower C(18) than L-forms cultured in the same media with added 0.5 M sucrose (950 mosmol) in both exponential and stationary cultures. In the stationary phase of growth, C(19) was reduced in the L-forms cultured without sucrose. Similar changes were seen in the parent S. faecalis cultured in the two types of media. These changes in membrane fatty acids may relate to osmo-regulation of the L-forms.

Production of the Shwartzman reaction with microbial L forms.

Study of potential pathogenicity of microbial L forms was done by the localized Shwartzman reaction. Stable L forms of Proteus mirabilis served as skin preparation in rabbits for induction of Shwartzman reaction by subsequent intravenous injection of either P. mirabilis L forms or Escherichia coli endotoxin. The intensity of the reaction was positively correlated to numbers of L forms in the skin. L forms also served as the intravenous challenge. In vivo multiplication of L forms was not a prerequisite for the reaction, as it could be produced with nonviable, osmotically lysed L forms. The reaction produced with L forms in the skin was more intense than that produced with the parent bacterial form. These latter observations, coupled with the demonstration that L forms disappeared from the skin (lysed?) after 4 hr, in contrast to bacteria which were recoverable for 72 hr (duration of study), suggest release of endotoxin by L forms as a pathogenic mechanism.

The role of antibiotic tolerance in the response to treatment of pyelonephritis due to Staphylococcus aureus in rats.

The effect of tolerance to methicillin on the response to treatment of hematogenous pyelonephritis due to Staphylococcus aureus was evaluated in rats. Tolerance was defined as a ratio of minimal bactericidal concentration to minimal inhibitory concentration of greater than or equal to 32. Rats that were infected with tolerant or nontolerant stains of S. aureus were treated with methicillin with equal success as judged by the number of bacteria in the kidneys and the proportion of rats with infected kidneys. In this animal model, tolerance does not play a role in the outcome of treatment.