BACTERIAL AGGLUTINATION BY A LECTIN FROM THE LEAVES OF THE MEDICINAL PLANT, PIMENTA DIOICA (L.) MERR

Objective: The current investigation involves the purification, characterization of the lectin from the leaves of Pimenta dioica (L.) Merr. (Myrtaceae) a medicinal plant, and its application in bacterial typing.Methods: A lectin was purified from the leaves by cation exchange chromatography. SDS PAGE revealed the molecular weight of the purified lectin. Biochemical characterization was carried out by performing various tests. Hemagglutination inhibition was conducted to detect the sugar specificity. Additionally, bacterial agglutination was performed to predict whether the purified lectin was able to agglutinate the bacterial strains.Results: SDS PAGE analysis revealed the lectin to be a tetramer in the range of 43-66 kDa. The purified lectin agglutinated human, avian, and mouse erythrocytes, and was inhibited by 125 mmol of mannose and xylose. The lectin was stable at 0-60 ° C for 30 min and was unaffected by either 2-Mercaptoethanol (2-ME) or Dithiothreitol (DTT) (50-250µM). A pH of 6.0–8.0 was found optimum for its activity and was nearly independent of metal ions. The purified lectin contained about 20% carbohydrate as estimated by Anthrone method. Purified lectin agglutinated the Gram-negative Escherichia coli and Proteus vulgaris.Conclusion: The isolated lectin was found to possess significant hemagglutinating activity. Due to its ability to agglutinate Gram negative bacteria such as Escherichia coli and Proteus vulgaris, it could be used for bacterial typing and for the design of bacterial filters.

Bacterial Filters in Anesthesia: Results of 9 Years of Surveillance

In 9 years of surveillance of postoperative lower respiratory infections, the infection rate in patients following regional anesthesia was 0.2% and 0.1% in patients following general anesthesia. No bacterial filters in the breathing circuit were used. Infected patients had risk factors such as type of surgery, American Society of Anesthesiologists class ≥2, old age, chronic obstructive pulmonary disease, or smoking habits. Infections were not clustered. This suggests that, in our setting, patient factors are most important in the development of postoperative lower respiratory infections and that the role of bacterial filters as a preventive measure is negligible.

Time-dependent Efficacy of Bacterial Filters and Infection Risk in Long-term Epidural Catheterization

Background Epidural infection represents a serious albeit infrequent complication of long-term epidural catheterization. The catheter hub is regarded as the main point of entry for microorganisms among the three possible routes (hematogenous, insertion site, hub) of microbial colonization of the inserted catheter. The current study was aimed at evaluating whether frequent changing of antimicrobial filters carries an increased risk of catheter hub contamination and the time-dependent efficacy of commonly used antimicrobial filters after prolonged use. Methods In the first part of the study, a microbiologic survey (skin, filter, hub, and catheter tip) was performed weekly in a group of 47 patients with cancer bearing subcutaneously tunneled catheters managed at home. Subsequently, the time-dependent efficacy of 96 micropore filters (32 Portex, 32 Sterifix-Braun, 32 Encapsulon TFX-Medical) differing in surface areas and/or composition of the filtering membrane was evaluated in a laboratory study. Filters were perfused, under the usual conditions of clinical use (flow resistance, injection pressure, temperature), every 8 h up to 60 days, with 5 ml of two different analgesic solutions, either sterile or containing 1.5 x 10(5)/ml of Streptococcus milleri I. Eight filters of each type subsequently were flushed with a S. milleri suspension (0.5 McFarland) after 7, 14, 28, and 60 days of continuous perfusion, and the resulting filtrates were cultured. Results In 16 of 19 positive hub cultures, the same microorganisms (species, biotype, antibiotype) were cultured from skin and filters. A statistically significant positive trend was found between the number of filter changes and the rate of positive hub cultures (chi 1(2) trend 5.11; P = 0.02). A high correlation coefficient was found between number of positive skin cultures and number of positive filtrates (r = 0.88; P = 0.01) and between number of positive filtrates and number of positive hub cultures (r = 0.93; P = 0.003). Cultures obtained from Portex and Sterifix-Braun filters yielded no bacterial growth (64/64) throughout the study period. Cultures from Encapsulon TFX-Medical filters showed bacterial growth 2/8 at seventh day, 7/8 at the 14th day, and 16/16 from the 28th day onward. Conclusions Our data indicate significant correlation between the incidence of catheter hub colonization and the filter-change frequency, when the skin close to the filter-hub connection is contaminated. Our results also show that Portex and Sterifix-Braun bacterial filters, when perfused with reduced volumes at low injection pressures, maintain an unmodified antimicrobial function for at least 60 days. Based on these data, it appears clinically feasible to reduce the frequency of filter changes during long-term epidural catheterization, with a consequent possible decrease of epidural catheter colonization.