Bacterial Filaments Induced by Antibiotic Minimal Inhibitory Concentrations in Persister Cells

Abstract

Background: The ability of minor subpopulations among clonal populations to survive antibiotics is referred to as bacterial persistence. It is believed that persisters come from latent cells, where antibiotic target areas are less active and incapable of being affected. Objective: 112 clinical Escherichia coli isolates were acquired out of diverse medical samples and genetically identified using the uspA gene, which is part of the housekeeping genes. Methods: The examination of persister cells was carried out by subjecting isolates of E. coli in the exponential phase with high dose of ciprofloxacin (20 fold MIC) and calculating the surviving persister cells using CFU (colony forming units) counts. The detection and measurement of bacterial filament production was done using scanning electron and light microscopy. Results: Results showed that the bacterial filament cells kept on lengthen but cease to divide (no septa formation) at sub-minimal inhibitory doses of ciprofloxacin. Persistent isolates were shown to exhibit a wide range of form and size variations, with cells up to 4.5 times longer than usual. Conclusions: The results showed the importance of antibiotic stress on persisted cells that result in the production of filaments as a means of survival and the need to examine these rare phenotypic variations. These occurrences may be the beginning of the spread of bacterial resistance.

Keywords

• E. coli
• persister
• filaments
• ciprofloxacin
• uspA gene