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Updated: Aug 14, 2026

A Protocol to Characterize the Morphological Changes of Clostridium difficile in Response to Antibiotic Treatment
Published on: May 25, 2017
Relative morphological effects induced by cefoxitin and other beta-lactam antibiotics in vitro
Abstract:
Cefoxitin, a new semisynthetic cephamycin antibiotic, induced filament formation at subinhibitory concentrations with a beta-lactamaseless strain of Enterobacter cloacae (HSC 18410 M66). The extent of filament induction by cefoxitin was similar to that seen with cephalothin, cefazolin, and benzylpenicillin. Filament induction by cefoxitin was markedly less than that seen with cephalexin, carbenicillin, ticarcillin, cephradine, and cephapirin. Antibiotics which failed to induce filaments at any level tested included cephaloridine, cephacetrile, cephalosporin C, the cephamycins, 6-aminopenicillanic acid, 7-aminocephalosporanic acid, A16884, A16886, and FL-1060. Those antimicrobial agents tested which lacked an aromatic substituent in the 7-position (for cephems) or in the 6-position (for penams) did not induce filaments. These observations suggest a possible relationship between filament induction of the test organism and the molecular nature of constituents in the 7- or 6-position of beta-lactams.
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