Staphylococcus aureus and Escherichia coli adhesion to human cells is reduced by sub-MICs of gemifloxacin

Cystone - An ayurvedic polyherbal formulation inhibits adherence of uropathogenic E. coli and modulates H2O2-induced toxicity in NRK-52E cells

Gentamicin is a widely used antibiotic for the treatment of adverse urinary tract infections (UTI), which in turn causes nephrotoxicity to uroepithelial cells and hence an alternative safe herbal remedy is much desired to compensate these toxic effects. The bacterial adhesion to the uroepithelial cells is the primary step in UTI and it induces various immunogenic reactions leading to the generation of reactive oxygen species (ROS), which are detrimental to the cells survival. Inhibition of bacterial adherence to urinary tract epithelial cells has been assumed to account for the beneficial action ascribed to cystone (an ayurvedic polyherbal formulation) in the prevention of UTI. In this study, we have examined the effect of cystone on the adherence of pathogenic [2-¹⁴C]-acetate labeled Escherichia coli (MTCC-729) to rat proximal renal tubular cells (NRK-52E cells). Further, the antioxidant property of cystone was studied using hydrogen peroxide (400 μM) as a pro-oxidant in NRK-52E cells. The results showed that cystone inhibited the adherence of E. coli to NRK-52E cells significantly. Additionally cystone effectively combats the toxicity induced by H₂O₂ in NRK-52E cells. The cytoprotective effect of cystone is brought about by inhibiting lipid peroxidation by 36% in cells treated with cystone compared to H₂O₂-treated cells without cystone. The antioxidant enzymes catalase, glutathione were increased by 53% and 68% respectively and superoxide dismutase activity was increased 3-fold. The glutathione content was significantly increased by 2.4-fold in NRK-52E cells treated with cystone compared to H₂O₂ control group. These results suggest that cystone effectively inhibits bacterial adherence to NRK-52E cells and attenuates H₂O₂-induced toxicity in NRK-52E cells by inhibiting lipid peroxidation and increasing the antioxidant defense mechanism.

Colonization with methicillin-resistant Staphylococcus aureus after liver transplantation

Methicillin-resistant Staphylococcus aureus (MRSA) is a frequent cause of infection after orthotopic liver transplantation (OLT). Colonization with MRSA is associated with a higher risk of infection. Previous studies have shown a high prevalence of MRSA colonization among OLT candidates. However, the risk of colonization with MRSA after OLT is still unclear. The objective of this study was to estimate the incidence and the factors associated with colonization with MRSA after OLT. This was a prospective cohort study including patients submitted to OLT between the years 2000 and 2002. Surveillance cultures of nasal swab specimens were performed within the 1st 72 hours of hospital admission and, subsequently, on weeks 2, 6, 13, and 26. Patients whose baseline cultures revealed nasal carriage of MRSA were excluded. A total of 60 patients were included in the study. The median follow-up was 72 days. A total of 9 patients (15%) became colonized. In multiple logistic regression analyses, the use of a urinary catheter for > or =5 days (P = .006), postoperative bleeding at the surgical site (P = .009), and preoperative use of fluoroquinolones (P = .08) were associated with a higher risk of colonization. Patients without any of these risk factors did not become colonized. In conclusion, nasal carriage of MRSA is frequently acquired after OLT. Periodic postoperative screening for MRSA carriage should be an integral component in programs designed to reduce nosocomial MRSA transmission in these patients. Further studies are needed to set up and validate a predictive model that could allow targeting postoperative screening to high-risk OLT recipients.

Gemifloxacin: effects of sub-inhibitory concentrations on various factors affecting bacterial virulence

This study investigated the ability of sub-MICs of gemifloxacin to interfere with the bacterial virulence parameters of adhesiveness, haemagglutination, hydrophobicity and motility, as well as their interactions with host neutrophilic defences such as phagocytosis, killing and respiratory bursts. The adhesiveness of both Escherichia coli and Staphylococcus aureus was significantly reduced to a subinhibitory concentration of 1/32 MIC. Indirect fimbriation parameters, such as hydrophobicity and haemagglutination were significantly reduced at a concentration of 1/8 MIC, as was migration (swarming). Phagocytosis and the respiratory burst measured by means of chemiluminescence were not affected, but killing was significantly increased from 1/2 to 1/8 MIC. The interpolation of these pharmacodynamic findings with pharmacokinetic curves indicates that sub-MIC concentrations of gemifloxacin can prolong antimicrobial effects on virulence determinants up to 27 h after the antimicrobial concentration has fallen below the MIC value.