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Relationship between morphological changes and endotoxin release induced by carbapenems in Pseudomonas aeruginosa
Toshinobu Horii1, Satoshi Ichiyama2, Michio Ohta1
1Departments of Bacteriology, Nagoya University School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya 466.
Abstract:
The relationship between morphological changes and endotoxin release induced in vitro by carbapenems in a clinical isolate of Pseudomonas aeruginosa was examined. The time-course and magnitude of endotoxin release induced varied among imipenem, panipenem, meropenem and biapenem and related to the morphological changes caused by these agents which variously affected cell shape, cell-wall disintegration and cell lysis. The amount of endotoxin released by carbapenem-treated cells correlated with both the cell-wall morphology and bacterial shape immediately before lysis. Meropenem and biapenem caused markedly increased endotoxin release during cell lysis and cell-wall disintegration, whereas imipenem and panipenem caused much less release of endotoxin.
Insights
Carbapenem antibiotics cause changes in Pseudomonas aeruginosa cell structure, leading to varied endotoxin release. Meropenem and biapenem induced more endotoxin release than imipenem and panipenem.
Area of Science:
- Microbiology
- Pharmacology
- Biochemistry
Background:
- Pseudomonas aeruginosa is an opportunistic pathogen.
- Carbapenems are broad-spectrum antibiotics.
- Endotoxins contribute to bacterial pathogenicity.
Purpose of the Study:
- To investigate the relationship between carbapenem-induced morphological changes and endotoxin release in Pseudomonas aeruginosa.
- To compare the effects of different carbapenems (imipenem, panipenem, meropenem, biapenem) on endotoxin release.
Main Methods:
- In vitro study using a clinical isolate of Pseudomonas aeruginosa.
- Exposure to four different carbapenem antibiotics.
- Microscopic examination of morphological changes (cell shape, cell-wall disintegration, lysis).
- Quantification of endotoxin release.
Main Results:
- Carbapenem-induced morphological changes varied among the tested agents.
- Endotoxin release magnitude correlated with cell-wall morphology and bacterial shape before lysis.
- Meropenem and biapenem caused significantly higher endotoxin release during cell lysis and cell-wall disintegration compared to imipenem and panipenem.
Conclusions:
- The extent of endotoxin release from Pseudomonas aeruginosa treated with carbapenems is dependent on the specific antibiotic and the resulting morphological alterations.
- Meropenem and biapenem appear to induce greater endotoxin release, potentially influencing the host inflammatory response, compared to imipenem and panipenem.