Biomedical subjects

Daniel W Scruggs

Publications and source records attributed to Daniel W Scruggs.

3 recordsLinked to original sources

PubMed2005

Effects of sub-minimum inhibitory concentration antibiotic levels and temperature on growth kinetics and outer membrane protein expression in Mannheimia haemolytica and Haemophilus somnus.

The objective of this study was to determine the effects of sub-minimum inhibitory concentrations (sub-MICs) of 2 veterinary antibiotic preparations, chlortetracycline (CTC) and chlortetracycline-sulfamethazine (CTC + SMZ), on growth kinetics and outer membrane protein expression in Mannheimia haemolytica and Haemophilus somnus at normal and febrile body temperatures. Sub-minimum inhibitory concentrations of both antibiotics reduced the growth rates of M. haemolytica and H. somnus. Growth of both species was not inhibited when grown at 41 degrees C compared to 37 degrees C. There was no detectable consistent effect of antibiotic or temperature on outer membrane protein expression for either species. Our study indicates that sub-MIC levels of CTC and CTC + SMZ markedly impair growth of clinical M. haemolytica and H. somnus isolates, potentially allowing more effective host clearance during infection.

Anti-Bacterial Agents↗

PubMed2004

Issues and challenges in developing long-acting veterinary antibiotic formulations.

Antibiotics are an important class of therapeutic agents, which are used for the treatment of bacterial infectious diseases in a variety of animal species. Antibiotic therapy varies from treatment period to administration routes, depending on the animal species or the type of the disease being treated. Despite the fact that there are a wide variety of commercially available antibiotics, difficulties and problems associated with the administration of antibiotics to animals still exist. Thus, there is a great need and tremendous opportunity to develop long-acting antibiotic formulations for veterinary applications. In this review article, common approaches used to develop long-acting antibiotic formulations are summarized. The challenges and issues related to the development of these long-acting formulations are also discussed.

Animals↗

PubMed2003

Alteration of DNA adenine methylase (Dam) activity in Pasteurella multocida causes increased spontaneous mutation frequency and attenuation in mice.

Pasteurella multocida is one of the primary bacterial pathogens associated with bovine respiratory disease (BRD) complex. Relatively few virulence factors of P. multocida have been characterized, and there is a need for improved vaccines for prevention of BRD. In other Gram-negative species, DNA adenine methylase (Dam) regulates the expression of virulence genes, and appropriate expression of Dam is required for virulence. In this study, the authors cloned and sequenced the P. multocida A1 dam gene and demonstrated that it is able to restore Dam function in an Escherichia coli dam mutant. When P. multocida dam was placed under the control of a constitutively expressed promoter on a plasmid, it caused an increased spontaneous mutation rate in P. multocida. In addition, the plasmid-mediated alteration of Dam production in P. multocida caused it to be highly attenuated in mice. These findings indicate that appropriate expression of Dam is required for virulence of P. multocida, which is believed to be the first report that Dam is required for virulence of a species in the Pasteurellaceae. Therefore, Dam may function as a virulence gene regulator in the Pasteurellaceae, similar to previously reported findings from other Gram-negative species.

Animals↗