Morphology of Escherichia coli Exposed to Penicillin as Observed with the Electron Microscope

Abstract

The morphological effects of penicillin on gram-negative nonsporeforming rods, especially E8cherichia coli, have been studied by several authors. Gardner (1940) reported that grotesque forms of E. coli resulted from autolytic swelling when this organism was treated with penicillin and that elongated, swollen cells resulted from incomplete fission. Weiss (1943) showed by electron micrographs that certain bacterial cells, when medicated with penicillin, became enlarged and fission was often incomplete. The effects of penicillin on intestinal bacteria as reported by Thomas and Levine (1945) included long twisting filaments in lower inhibitory concentrations and cells resembling Pasteur flasks, swelled fusiform rods, large globular cells, and irregular masses in higher concentrations. In concentrations just above those with visible growth, globular masses were found upon centrifugation and examination of the sediment. Normal rods were cultivated from the masses in the sediment. In the same year Alture-Werber, Lipschitz, Kashdan, and Rosenblatt (1945)-studied the effect of incompletely inhibitory concentrations of penicillin on Escherichia coli. These authors found organisms resembling budding fungi in the urine of patients treated with penicillin. Culturing for molds was negative, but E. coli was isolated on other media and it was concluded that penicillin was responsible for the funguslike appearance of the cells in urine. This assumption was confirmed by in vitro experiments using MacConkey's agar to which was added varying concentrations of penicillin. Morphological changes noted were diphtheroidlike, bipolar cells at 75 units per ml.; unsegmented filaments with myceliallike appearance at 100 informative review of the action of penicillin and its effect on bacterial morphology was given by Fisher (1946). Morphological variation may be induced by agents or conditions other than by the use of penicillin. Only a few of the more important aspects of the phe-183

Observations on Bacteria Sensitive to, Resistant to, and Dependent upon Streptomycin

“…The pleomorphic forms of the streptomycin-dependent variants grown in sub. optimal amounts of streptomycin were similar to those observed by many workers when organisms were grown under unfavorable cdnditions (Dienes, 1947;Gardner, 1925Gardner, , 1945Gay and Clark, 1937;Shanahan, Eisenstark, and Tanner, 1947;Tunnicliff, 1939;Walker and Murray, 1904;Wyckoff, 1933Wyckoff, , 1934.…”

A Study of Large Bodies in Azotobacter Agile

“…Reports of toxic agents that produce large bodies are numerous (Shanahan et al, 1947;Johnson and Gray, 1949;Duguid, 1946;Tulasne, 1949a), and a series of these agents were added in several concentrations to the basal medium, including penicillin, streptomycin, aureomycin, bacitracin, tyrothricin, sulfonamides, colchicine, podophyllin, nitrogen mustard, radioactive phosphorus, so-6A. EISENSTARK, C. B.…”

Cytochemical Interpretation of the Mechanism of Penicillin Action 1

“…A. Morphological.-It is well known that bacteria under the influence of bactericidal concentrations of penicillin undergo distortion and swelling and ultimate lysis (3,10,15,51,68,69,80,82,114,117,128,129,148,172,174,181,182,194,196). Microscopical examination of assay plates seeded with different test organisms shows that the cells not only increase in size, but tend to become concatenated.…”