Bacteriostatic and bactericidal effects of antibiotics on Bacteroides

The bacteriostatic or bactericidal action of metronidazole, clindamycin, tetracycline, chloramphenicol, cefoxitin and penicillin were determined against sixteen Bacteroides fragilis strains and six B. thetaiotaomicron strains. Drugs were considered bactericidal when minimal bactericidal concentration (MBC) to minimal inhibitory concentration (MIC) ratios were less than or equal to four. As expected, metronidazole, cefoxitin and penicillin were bactericidal. However, clindamycin and chloramphenicol, which other investigators have considered as bacteriostatic antibiotics, were bactericidal. Tetracycline was irregularly bactericidal. When tested against Escherichia coli, tetracycline and chloramphenicol were bacteriostatic as reported by others. The MBCs of metronidazole, clindamycin and tetracycline were well within the clinically achievable levels of each drug. Death rate data confirmed these findings. With tetracycline, chloramphenicol and metronidazole MICs and MBCs increased as inocula sizes increased, however, with clindamycin and cefoxitin only MBCs increased. Clindamycin was administered to mice which had pure B. fragilis abscesses. Over 8 h cell numbers in the pus remained relatively constant even though, during this same period, the concentration of clindamycin in the pus was above the MBC of this drug for the strain used.

Name thesis:degree_name

M.S.

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Microbiology

Department dc:contributor.department

Microbiology

Grantor dc:publisher

Virginia Polytechnic Institute and State University

Year dc:date.issued

1978

Author dc:creator

• Veltri, Benjamin James

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en

Handle dc:identifier.uri

http://hdl.handle.net/10919/106241

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/106241