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Ultrastructure of staphylococci in respiratory infections treated with nafcillin
Abstract:
A patient with a pleural effusion containing Staphylococcus aureus was treated with nafcillin. Another patient with bilateral upper lobe infiltrates which grew S. aureus from a catheter inserted through a fiberoptic bronchoscope into the lesion was also treated with nafcillin. Electron microscopy of organisms grown while the patients were receiving nafcillin showed staphylococci which were twice as large as normal and contained multiple cross-walls and normal peripheral cell walls. Such abnormal staphylococci result from exposure to subminimum inhibitory concentrations of beta-lactam antibiotics.
Insights
Nafcillin treatment caused Staphylococcus aureus to grow abnormally large with multiple cross-walls. This occurs when bacteria are exposed to sub-minimum inhibitory concentrations of beta-lactam antibiotics.
Area of Science:
- Microbiology
- Infectious Diseases
- Pharmacology
Background:
- Staphylococcus aureus infections, including pneumonia and pleural effusion, require effective antibiotic treatment.
- Nafcillin is a beta-lactam antibiotic commonly used against S. aureus.
Observation:
- Two patients with S. aureus infections were treated with nafcillin.
- Electron microscopy was used to examine S. aureus morphology during nafcillin therapy.
Findings:
- Staphylococci exposed to nafcillin exhibited significant morphological changes, appearing twice the normal size.
- Abnormal bacteria displayed multiple internal cross-walls while maintaining normal peripheral cell walls.
Implications:
- Sub-minimum inhibitory concentrations of beta-lactam antibiotics induce distinct morphological alterations in S. aureus.
- Understanding these antibiotic-induced changes is crucial for monitoring treatment efficacy and potential resistance mechanisms.