Correlation between antibiotic resistance, phage-like particle presence, and virulence in Rhodococcus equi human isolates
| Autor: | F Espinasse, Patrice Nordmann, M Keller, E. Ronco |
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| Rok vydání: | 1994 |
| Předmět: |
Microbiology (medical)
Lactams medicine.drug_class Antibiotics Mice Nude Virulence Biology Virus Microbiology Bacteriophage Mice Antibiotic resistance Rhodococcus equi medicine Animals Humans Bacteriophages Pathogen AIDS-Related Opportunistic Infections Drug Resistance Microbial biology.organism_classification Anti-Bacterial Agents Microscopy Electron Phenotype Mutation Female Actinomycetales Infections Bacteria Research Article |
| Zdroj: | Journal of Clinical Microbiology. 32:377-383 |
| ISSN: | 1098-660X 0095-1137 |
| Popis: | Rhodococcus equi is a gram-positive coccobacillus that appears to be emerging as a pulmonary pathogen in AIDS patients. In four human clinical isolates, two antibiotic resistance phenotypes were found to coexist: one beta-lactam resistant and the other beta-lactam susceptible. In vitro, beta-lactam-resistant mutants were obtained at a frequency of 1 x 10(-5) to 5 x 10(-5) from beta-lactam-susceptible strains on cephalothin-containing plates. Neither beta-lactamase nor plasmid DNA was detected in beta-lactam-resistant or -susceptible strains. The penicillin-binding protein patterns for the two types of strains were identical. Electron microscopy revealed that the beta-lactam-resistant strains possessed cell-surface-associated appendages and produced phage-like particles. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of total cell protein showed at least three additional bands of 42, 39, and 30 kDa found only in the beta-lactam-resistant strains. Testing for virulence in Swiss mice revealed that (i) phage-like-particle-producing strains had lower 50% lethal doses when injected intravenously in euthymic and nude mice than the non-phage-like-particle-producing strains did and (ii) intravenous inoculation of a sublethal dose (5 x 10(6) CFU) in nude mice led to chronic infection by the phage-like-particle-producing bacteria only. Finally, in vitro growth curves indicated that the phage-like-particle-producing strains possessed an ecological selection advantage. These results suggest that, among R. equi human isolates, the antibiotic resistance phenotype is associated with virulence and may be phage mediated. |
| Databáze: | OpenAIRE |
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