This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Cano, D. A. Articles by García-del Portillo, F. Search for Related Content PubMed PubMed Citation Articles by Cano, D. A. Articles by García-del Portillo, F. Pubmed/NCBI databases Gene Protein

 Previous Article  |  Next Article 

Infection and Immunity, July 2003, p. 3690-3698, Vol. 71, No. 7
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.7.3690-3698.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

Selection of Small-Colony Variants of Salmonella enterica Serovar Typhimurium in Nonphagocytic Eucaryotic Cells

David A. Cano,^1, M. Graciela Pucciarelli,² Marina Martínez-Moya,³ Josep Casadesús,¹ and Francisco García-del Portillo^2*

Departamento de Genética, Facultad de Biología, Universidad de Sevilla, 41080 Seville,¹ Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología, Consejo Superior de Investigaciones Científicas (CSIC), Campus de Cantoblanco,² Centro de Biología Molecular Severo Ochoa, Universidad Autónoma de Madrid, 28049 Madrid, Spain³

Received 16 January 2003/ Returned for modification 19 March 2003/ Accepted 31 March 2003

Salmonella enterica strains are enteropathogenic bacteria that survive and proliferate within vacuolar compartments of epithelial and phagocytic cells. Recently, it has been reported that fibroblast cells are capable of restricting S. enterica serovar Typhimurium intracellular growth. Here, we show that prolonged residence of bacteria in the intracellular environment of fibroblasts results in the appearance of genetically stable small-colony variants (SCV). A total of 103 SCV isolates, obtained from four independent infections, were subjected to phenotypic analysis. The following phenotypes were observed: (i) -aminolevulinic acid auxotrophy; (ii) requirement for acetate or succinate for growth in glucose minimal medium; (iii) auxotrophy for aromatic amino acids; and (iv) reduced growth rate under aerobic conditions not linked to nutrient auxotrophy. The exact mutations responsible for the SCV phenotype in three representative isolates were mapped in the lpd, hemL, and aroD genes, which code for dihydrolipoamide dehydrogenase, glutamate-1-semyaldehyde aminotransferase, and 3-dehydroquinate dehydratase, respectively. The lpd, hemL, and aroD mutants had intracellular persistence rates in fibroblasts that were 3 to 4 logs higher than that of the parental strain and decreased susceptibility to aminoglycoside antibiotics. All three of these SCV isolates were attenuated in the BALB/c murine typhoid model. Complementation with lpd⁺, hem⁺, and aroD⁺ genes restored the levels of intracellular persistence and antibiotic susceptibility to levels of the wild-type strain. However, virulence was not exhibited by any of the complemented strains. Altogether, our data demonstrate that similar to what it has been reported for SCV isolates of other pathogens, S. enterica SCV display enhanced intracellular persistence in eucaryotic cells and are impaired in the ability to cause overt disease. In addition, they also suggest that S. enterica SCV may be favored in vivo.

---

* Corresponding author. Mailing address: Departamento de Biotecnología Microbiana, Centro Nacional de Biotecnología—CSIC, Campus de Cantoblanco, 28049 Madrid, Spain. Phone: (34) 91 5854923. Fax: (34) 91 5854506. E-mail: fgportillo{at}cnb.uam.es.

Editor: B. B. Finlay

Present address: Diabetes Center, Department of Medicine, University of California, San Francisco, San Francisco, CA 94143-0540.

---

Infection and Immunity, July 2003, p. 3690-3698, Vol. 71, No. 7
0019-9567/03/$08.00+0     DOI: 10.1128/IAI.71.7.3690-3698.2003
Copyright © 2003, American Society for Microbiology. All Rights Reserved.

This article has been cited by other articles:

• Norstrom, T., Lannergard, J., Hughes, D. (2007). Genetic and Phenotypic Identification of Fusidic Acid-Resistant Mutants with the Small-Colony-Variant Phenotype in Staphylococcus aureus. Antimicrob. Agents Chemother. 51: 4438-4446 [Abstract] [Full Text]  
• Rea, R., Hill, C., Gahan, C. G. M. (2005). Listeria monocytogenes PerR Mutants Display a Small-Colony Phenotype, Increased Sensitivity to Hydrogen Peroxide, and Significantly Reduced Murine Virulence. Appl. Environ. Microbiol. 71: 8314-8322 [Abstract] [Full Text]