Use of scanning electron microscopy to investigate the prophylactic efficacy of rifampin-impregnated CSF shunt catheters

Abstract

Infection continues to be one of the major complications of cerebrospinal¯uid (CSF) shunting procedures, and is caused mainly by skin-derived bacteria. Production of an extracellular bio®lm plays an important role in the pathogenesis of shunt-associated infections by protecting bacteria from immune mechanisms and antibiotics. So far, removal of the original shunt and implantation of a new shunting device has been the only successful treatment for most patients. As an alternative strategy to prevent CSF infections, a rifampin-impregnated silicone catheter was designed to provide high initial and long-lasting (>60 days) release of bactericidal drug. To investigate the pathophysiological mechanism of its function, this new device was investigated both in vitro and in a rodent model of CSF infection by scanning electron microscopy (SEM) and bacterial culture. Staphylococcus epidermidis (10 8 cfu=ml) and S. aureus (10 4 cfu=ml) served as test strains. SEM demonstrated that, in contrast to the unloaded catheters, initial bacterial adherence on the catheter surface could be reduced to a few single cells, which did not show visible signs of proliferation. Bacterial cultures obtained simultaneously were all sterile, showing that adherent bacteria were killed immediately by the rifampin released from the catheter. Although rifampin incorporation into silicone polymers was not able to prevent initial bacterial adhesion completely, subsequent colonisation could be prevented.

Antibacterial mode of action of <i>Ginkgo biloba</i> leaf essential oil: Effect on morphology and membrane permeability

“…Control samples were prepared without the G. biloba leaf essential oil. Further, to observe the morphological changes, the SEM was modified from the Kockro method (Kockro et al, 2000;Bajpai et al, 2009). The bacterial sample was washed gently with 50 mM/L phosphate buffer solution (pH 7.2), fixed with 2.5%, 100 mL glutaraldehyde and 100 mL osmic acid solution (1%).…”

Biofilm characteristics of Staphylococcus epidermidis isolates associated with device-related meningitis

“…However, this can be complicated by infections such as meningitis, often caused by coagulase-negative staphylococci (CoNS), with Staphylococcus epidermidis being isolated most frequently (Diaz-Mitoma et al, 1987). Mounting evidence suggests that such infections are a result of biofilm formation on the device (Diaz-Mitoma et al, 1987;Tojo et al, 1988;Kockro et al, 2000).…”

“…However, this can be complicated by infections such as meningitis, often caused by coagulase-negative staphylococci (CoNS), with Staphylococcus epidermidis being isolated most frequently (Diaz-Mitoma et al, 1987). Mounting evidence suggests that such infections are a result of biofilm formation on the device (Diaz-Mitoma et al, 1987;Tojo et al, 1988;Kockro et al, 2000).Staphylococcal biofilm formation involves both host and bacterial factors. Early investigations have shown that production of polysaccharide is a primary mechanism employed by S. epidermidis (Peters et al, 1987;Tojo et al, 1988; Christensen et al, 1990;Mack et al, 1992).…”

Antimycotic potential of a diterpenoid taxoquinone against <i>Candida</i> species isolated from <i>Metasequoia glyptostroboides</i>

“…Controls were prepared without test compound. To observe the morphological changes, the method of SEM was modified from Kockro method (Kockro et al, 2000). The fungal samples were washed gently with 0.1 M phosphate buffer solution (pH 7.2), and fixed with 2.5% (w/v) glutaraldehyde.…”