In vitro activity of linezolid in combination with photodynamic inactivation against Staphylococcus aureus biofilms

Background: Biofilm infections are a major challenge in medical practice. Bacteria that live in a biofilm phenotype are more resistant to both antimicrobial therapy and host immune responses compared to their planktonic counterparts. So, there is need for new therapeutic strategies to combat these infections. A promising approach [known as Photodynamic Inactivation [PDI]] to kill bacteria growing as biofilms uses light in combination with a photosensitizer to induce a phototoxic reaction which produces reactive oxygen species that can destroy lipids and proteins causing cell death. PDI does not always guarantee full success, so, combination of PDI with antibiotics may give increased efficiency. This study aimed to determine if PDI was effective in the eradication of Staphylococcus aureus [S. aureus] biofilms in combination with linezolid

Methods: The susceptibility of biofilm cultures of three S. aureus strains to Methylene Blue [MB] and Toluidine Blue O [TBO]-mediated PDI was determined alone and in combination with linezolid

Results: Bactericidal activity [>/=3 log[10] reduction in viable cell count] was not achieved with MB/TBO-PDI or antibiotic treatment alone. When antibiotic treatment was combined with TBO-PDI, a greater reduction in viable count than antibiotic alone was observed for two strains

Conclusion: This study showed that although TBO-PDI did not have good bactericidal activity against S. aureus biofilms; it increased the antimicrobial activity of linezolid against these bacteria

Breastfeeding and Helicobacter pylori infection in children with digestive symptoms

This study aims to evaluate the role of breastfeeding in the acquisition of Helicobacter pylori [H. pylori] infection in Iran and to compare the histopathologic changes occurring in children feeding on breast milk with those in infants feeding on formula. In a case-control study parents of children with and without H. pylori infection who had undergone endoscopic survey and gastric biopsy in the Children's Medical Center, Tehran, were asked about their feeding practices during the first 6 months after birth, the duration of breastfeeding period, the symptoms, and the duration of symptoms and concomitant diseases. A total of 154 children were included in this study. From this sample, 77 children formed the case group and 77 children formed the control group. A significant difference was found between H. pylori infection and feeding with formula [P=0.045]. In case group, a significant difference was found between breastfeeding and age of the infected child [P=0.034], shorter duration of symptoms [P=0.016], and finally degree of H. pylori colonization [P=0.021]. It appears that breastfeeding in the first 6 months after birth can decrease the degree of H. pylori colonization, postpone infection until older age, shorten the duration of symptoms, and be concomitant with milder gastritis