The response of Pseudomonas aeruginosa to azlocillin, ticarcillin and cefsulodin

Morphological and ultrastructural changes in bacterial cells as an indicator of antibacterial mechanism of action

“…Cefuroxime and ceftazidime, which have a higher affinity for PBP3 than PBPs 1a, 1b or 2 [76,120], cause E. coli and P. aeruginosa to form filaments relatively quickly (within 3-4 hours) at low antibiotic concentrations (0.008xMIC to 1xMIC), with spheroplast formation or lysis becoming observable at 0.5xMIC and increasing at higher concentrations [54,76,120]. This transition from filaments to spheroplasts or lysis also increases with duration of antibiotic exposure [55]. The β-lactam induced formation of filaments occurs, not just in E. coli and P. aeruginosa, but in many species of Gram-negative bacteria [49,53,65,74,81,[121][122][123] and a limited number of Gram-positive bacteria [124][125][126].…”

“…Other variables known to influence results relate to the test organism and incubation conditions. Bacterial factors affecting morphostructural changes include the cell wall structure of the test organism (Gram-positive vs Gram-negative) [50], the species that is used [51,52], the characteristics of the test strain (including its antibiotic susceptibility) [53,54], and the inoculum density [55,56]. Growthphase affects the size, shape, and cell wall thickness of bacteria even in the absence of antibacterial agent, stationary phase cells being smaller [57,58], having a lower axial ratio [57], and a thicker cell wall [59,60] than logarithmically growing cells.…”

The pathogenesis of urinary tract infections associated with Escherichia coli, Staphylococcus saprophyticus and S. epidermidis

“…Finally the samples were placed in acetone as previously described. 12 The tissue was then dried in a critical point dryer (Polaron Equipment) and coated with gold for 2 min in a sputter coater (EM Scope) as previously described. 13 The specimens were examined in a Cambridge S600 stereoscan electronmicroscope.…”

A Study of Scanning Electron Microscope of Vancomycin Resistant <i>Enterococcus faecalis</i> from Clinical Isolates

“…Many studies have demonstrated that E. faecium is comparatively mores resistant than E. faecalis. [14]. The E. faecalis isolates investigated demonstrated resistance to vancomycin (MICs, 32 to 64, uglml).…”

“…Scanning electron microscopy offers the unique ability to examine surface structures at relatively high resolution and proves particularly useful in the examination of the effect of antibiotics that act on the bacterial cell wall [12][13][14]. The present study describes the effect of antibiotic stress on the morphology of vancomycin resistant E. faecalis strains examined by scanning electron microscopy.…”