rifampin and Salmonella-Infections--Animal

SmpA is a small outer-membrane lipoprotein that is a component of the essential YaeT outer-membrane protein assembly complex. In Salmonella enterica serovar Typhimurium (S. Typhimurium), expression of the smpA gene was shown to be directed by two promoters, smpAp1 and smpAp2. The more distal promoter, smpAp1, is dependent upon the extracytoplasmic stress response sigma factor sigma(E). An smpA null mutant was constructed in S. Typhimurium SL1344 and was shown to be more sensitive than its wild-type parent to growth at high temperature and in the presence of sodium cholate, SDS plus EDTA, and the hydrophobic antibiotic rifampicin. The lack of SmpA in S. Typhimurium elicits a sigma(E)-dependent stress response. These findings are indicative of altered outer-membrane integrity in the smpA mutant, probably due to a defect in outer-membrane protein biogenesis. SmpA was not important for entry or survival within murine macrophages; however, the S. Typhimurium smpA mutant was attenuated in mice by both the oral and parenteral routes of infection, and SmpA appeared to be most important for the growth of S. Typhimurium at systemic sites.

Topics: Animals; Anti-Bacterial Agents; Bacterial Outer Membrane Proteins; Bacterial Proteins; Base Sequence; Edetic Acid; Gene Deletion; Gene Order; Hot Temperature; Lethal Dose 50; Liver; Lymph Nodes; Macrophages; Mice; Mice, Inbred BALB C; Microbial Viability; Molecular Sequence Data; Peyer's Patches; Promoter Regions, Genetic; Rifampin; Salmonella Infections, Animal; Salmonella typhimurium; Sigma Factor; Sodium Dodecyl Sulfate; Spleen; Transcription Factors; Transcription, Genetic; Virulence; Virulence Factors

We used the ability of Salmonella enterica serovar Typhimurium to colonize the gut of Caenorhabditis elegans to measure the fitness costs imposed by antibiotic resistance mutations. The fitness costs determined in the nematode were similar to those measured in mice, validating its use as a simple host model to evaluate bacterial fitness.

Topics: Animals; Caenorhabditis elegans; Disease Models, Animal; Drug Resistance, Multiple, Bacterial; Mice; Salmonella Infections, Animal; Salmonella typhimurium

The number of viable cells of two strains of Salmonella typhimurium and the number of viable cells and the cell size of the colon microbiota of mice were examined during non-growing conditions after exposure to antibiotics with known modes of action. Salmonella typhimurium starved for 1, 2, 4, 5, 12 and 20 d in a phosphate buffer saline solution and subsequently exposed for 2 and 6 h showed the following characteristics. The protein synthesis inhibitors gentamicin and tetracycline, the RNA synthesis inhibitor rifampicin and the membrane potential inhibitor polymyxin all impaired survival of starved cells. The reduction in the number of viable cells caused by the addition of gentamicin, rifampicin and polymyxin was generally more pronounced with extended exposure to energy and nutrient deprivation. Both 2- and 6-h exposure of tetracycline, however, had diminishing inhibitory effects after 20 d compared with 5 d of starvation. Control experiments to verify non-growing conditions in the starvation regime showed that DNA and cell wall synthesis inhibitors had no inhibitory effect after 24-h starvation. The rough mutant strain displayed a lower sensitivity to a hydrophobic rather than a hydrophilic inhibitor as compared to the smooth wild-type strain. The cell size reduction but not viability was partly prevented by protein synthesis inhibitors as seen for both in vivo and in vitro colon microbiota studies.

Topics: Animals; Anti-Bacterial Agents; Bacterial Proteins; Cell Wall; Colon; Colony Count, Microbial; Food Deprivation; Gentamicins; Lactams; Mice; Mice, Inbred BALB C; Nalidixic Acid; Polymyxins; Rifampin; RNA, Bacterial; Salmonella Infections, Animal; Salmonella typhimurium; Tetracycline

Topics: Animals; Cephaloridine; Escherichia coli; Escherichia coli Infections; Infections; Klebsiella; Klebsiella Infections; Listeria monocytogenes; Listeriosis; Mice; Pasteurella; Pasteurella Infections; Pneumococcal Infections; Rifampin; Salmonella Infections, Animal; Salmonella typhimurium; Staphylococcal Infections; Staphylococcus; Streptococcus pneumoniae

Topics: Animals; Cephaloridine; Drug Resistance, Microbial; Mice; Pasteurella; Pasteurella Infections; Rifampin; Salmonella Infections, Animal; Salmonella typhimurium; Time Factors