Evaluation of two different semi-automated homogenization techniques in microbiological diagnosis of periprosthetic joint infection: disperser vs. bead milling method.

BACKGROUND: In microbiological diagnosis of periprosthetic joint infection (PJI) there is no consensus regarding the most suitable and optimal number of specimens to be cultured or the most effective technique of tissue processing. This comparative study analysed the accuracy of two semi-automated homogenization methods with special focus on the volume and exact origin of each sample. METHODS: We investigated a total of 722 periprosthetic tissue samples. PJI was defined according to the new scoring system for preoperative and intraoperative criteria. We compared the performance of our routinely used single tissue processing by disposable high-frequency disperser with the bead milling method. RESULTS: Eighty patients were included. Among forty classified PJIs, 34 patients yielded positive culture results. In 23 cases (68%) exact concordant results were generated with both techniques. However, in seven cases (20%) processing by the disperser and in four cases (12%) by bead milling provided additional positive samples, but without significant difference since the major definition criteria were met in all cases. The percentage of positive results was influenced by the volume and origin of the tissue samples. Results for small tissue samples tended to be better using the bead milling method. This might lead to improved preoperative arthroscopic diagnosis, as the volume of biopsies is generally limited. Six patients had negative results due to previous antimicrobial therapy. Forty other patients were classified as aseptic failures. Neither procedure resulted in any contamination. CONCLUSION: Both methods enable reliable processing of tissue samples for diagnosis of PJI and are suitable for routine use.

High prevalence of significant liver fibrosis and cirrhosis in chronic hepatitis B patients with normal ALT in central Europe.

The indication for antiviral treatment of patients with chronic hepatitis B is based on serum HBV DNA levels, transaminases, and histological grade and stage. The relation of liver fibrosis and inflammation to ALT activity in chronic hepatitis B infection was investigated in a nonendemic, European setting. A total of 253 patients with chronic hepatitis B who had undergone liver biopsy at the Clinic of Gastroenterology, Hepatology, and Infectious Diseases, Düsseldorf,Germany over the past 19 years (1990­2009) were evaluated. Thirty-nine patients had persistently normal transaminases, 86 patients had ALT with 1­2 x ULN (upper limit of normal) and 128 patients had ALT >2 x ULN. Liver fibrosis or inflammation was defined as significant for stages or grades ≥ 2 according to the Desmet/Scheuer score. Significant liver fibrosis (F ≥ 2)was found in 36%, cirrhosis in 18%, and significant inflammation (G ≥ 2) in 27% of patients with normal transaminases. There was no difference in the stage of liver fibrosis and the frequency of cirrhosis between patients with normal and elevated transaminases. The most important factor associated with the presence of cirrhosis in multivariate analysis was age ≥ 40 years (P < 0.003). If concomitant factors like elevated GGT or male sex were furthermore present high prevalences of significant liver disease were found. The data indicate that, in a European setting, patients with chronic hepatitis B infection, and normal transaminases frequently have significant liver fibrosis or cirrhosis.Therefore, liver biopsy or liver stiffness measurement (LSM) should be performed in these patients to determine the stage of liver fibrosis.