Chitosan-based hydrogels to treat hydrofluoric acid burns and prevent infection.

There is an urgent need for treatments for hydrofluoric acid (HF) burns and their derivative problems that prevent hydrogen ion dissociation and fluoride ion binding to tissues. This study evaluated the ability of chitosan-based hydrogels combined with a buffer solution containing either boric acid or Tris and calcium gluconate (CHS-BA-CG and CHS-Tris-CG) to repair HF burn wounds and prevent wound infections. We assessed calcium release rates and biocompatability and constructed a mouse HF burn model to assess the tissue repair effects of the hydrogels. Finally, we performed disc diffusion tests from burn tissue and quantified the bacterial counts to assess the anti-infection properties of the hydrogels. Calcium was gradually released in the CHS-BA-CG and CHS-Tris-CG groups (73% and 43%, respectively, after 48 h). The cell viabilities at 48 h after HF burn in these groups were significantly higher than those in the phosphate-buffered saline (PBS) and CG-treated groups. Histopathological evaluation showed a clear boundary between the epidermal and dermal layers in both CHS-BA-CG and CHS-Tris-CG-treated groups, indicating their effectiveness in tissue repair. In the disc diffusion test, CHS-BA-CG and CHS-Tris-CG exhibited larger inhibition zones against Acinetobacter baumannii than those for PBS and CG. The bacterial counts on HF burn wounds were significantly lower in the CHS-BA-CG and CHS-Tris-CG-treated groups than those in the PBS and CG-treated groups. The in vitro studies demonstrated the biocompatibility and antimicrobial effects of the CHS-BA-CG and CHS-Tris-CG hydrogels. Both gels also demonstrated tissue repair and anti-infection effects. Thus, chitosan-based hydrogels may be candidates for HF burn therapy.

Increasing opsonizing and killing effect of serum from patients with recurrent K1 Klebsiella pneumoniae liver abscess.

BACKGROUND: Klebsiella pneumoniae liver abscess (KLA) is an emerging infectious disease caused by the virulent K pneumoniae strains of capsular serotype K1 and commonly associated with diabetes mellitus. Recurrent KLA is rarely reported and the mechanism of recurrence is uncertain. In this study we evaluated both phagocytosis by neutrophils and serum killing ability of serum from recurrent K1 KLA patients compared to normal healthy subjects (NHS). METHODS: This prospective study included six cases of recurrent K1 KLA consisting of three male and three female patients with a mean age of 67.2 years (range, 56-88 years). The different serotypes of K pneumoniae were reacted with serum from patients with recurrent KLA and NHS. Subsequent phagocytosis by neutrophils was determined using flow cytometry and serum killing assays were performed. RESULTS: The most common underlying disease in patients with recurrent KLA was diabetes mellitus, occurring in about 83.3% (5/6) of patients. The antibiogram of the strains associated with recurrent KLA remained uniquely resistant to ampicillin. The average percentage derived from the serum killing assays showed serotype K1 and K2 resistance to serum from NHS (1281% and 621%, respectively); however, serum susceptibly was observed in the serum of patients with recurrent K1 KLA (0.3% and 1.1%, respectively). A significant increase in neutrophil phagocytosis of serotype K1 was observed following opsonisation with serum from patients with recurrent KLA compared with serum from NHS (p = 0.008). No significant difference in the phagocytic rate of non-K1/K2 or K2 serotypes was observed between NHS and patients with recurrent KLA (p = 0.76 and p = 0.132, respectively). CONCLUSION: These preliminary results showed possible immunologic protection in patients with recurrent KLA due to increasing opsonization and serum killing.