A simple infection model using pre-colonized implants to reproduce rat chronic Staphylococcus aureus osteomyelitis and study antibiotic treatment.

Staphylococcus aureus biofilms formed on medical implants represent a serious problem, being difficult to eradicate with antibiotic therapy and leading to chronic infections. Simplified in vivo and in vitro antibiotic susceptibility assays using biofilm bacteria are needed. In this work, a novel chronic osteomyelitis infection model was developed in rats in the absence of bacterial suspension, requiring the use of only 10(6) bacteria in biofilms at the site of surgery, with a full success in reproducing infection. Stainless-steel implants pre-colonized for 12 h with a highly adherent S. aureaus isolate were introduced into the rat tibiae. In animals not submitted to antibiotic treatment, infection was found in the implants and spread to bone in all cases, indicating the high efficacy of the model to reproduce osteomyelitis. The effect of a 21-day treatment with cefuroxime, vancomycin, tobramycin or ciprofloxacin on infection was studied in this model 42 days after surgery. Bone colonization was inhibited by vancomycin and cefuroxime. Cefuroxime (the most efficient antibiotic, able to sterilize 1 out of 8 implants) reduced the number of bacteria in biofilms adhered to implants at a higher extent than vancomycin, trobramycin and ciprofloxacin. Analogous observations were made in this work in vivo and in vitro on the relative antibiotic efficacy against S. aureus biofilm bacteria. suggesting the usefulness of both tests as a potential tool to study antibiotic suceptibility, and the need for new antimicrobials against these bacteria.

Autologous blood transfusion as an immunomodulator in experimental sepsis.

BACKGROUND: Homologous blood transfusion is associated with immunosuppressive consequences. Some clinical and experimental studies have suggested an immunostimulating action of autologous blood transfusion. The aim of this paper is to ascertain the effects of either homologous blood transfusion or autologous blood transfusion on the lymphocyte subsets and cytokines in a model of intra-abdominal sepsis. MATERIALS AND METHODS: There were three study groups. Group A: 10 Wistar-Furth (WF) rats underwent cecal ligation and puncture (CLP) aimed at causing an intra-abdomial sepsis; Group B: 10 WF rats underwent CLP plus 1 ml homologous blood perioperative transfusion obtained from Fisher-344 rat while Group C: 10 WF rats underwent CLP plus 1 ml autologous blood perioperative transfusion. Changes of peripheral lymphocyte subsets, percentages of total T-lymphocytes (CD3), Helper T-lymphocytes (CD4), supressor/cytotoxic T-lymphocytes (CD8), CD4/CD8 ratio, Interleukin-2 receptor expression (IL-2R) and cytokines IL-1 and TNF-alpha were measured in peripheral blood on the preoperative, 1st, 3rd and 7th postsepsis (PO) days. RESULTS: Rats in homologous transfused group showed a decrease of %CD4 on the 3rd PO (from preoperative to 3rd PO;p < 0.01; and from 1st to 3rd PO; p < 0.05) and on the 7th PO (from preoperative to 7th PO; p < 0.05); %CD8 increased from preoperative to 3rd PO (p < 0.05), from 1st to 3rd PO (p < 0.01) and from 1st to 7th PO (p < 0.05). An initial decrease on day 1 (p < 0.01) followed by an increase on the 3rd PO (p < 0.01) with regard to IL-2R and a significant increase of IL-1 levels within the first 24h (p < 0.01). Rats in autologous transfused group showed an increase of %CD3 from preoperative to 7th PO (p < 0.05), and from 3rd to 7th PO (p < 0.01). CONCLUSIONS: We observed that homologous blood transfusions induce a greater alteration in the cellular immune response and of the cascade of cytokines than autologous transfusions. This modulates the variations of the immune response induced by sepsis.

S-adenosylmethionine immunomodulator treatment in sepsis.

BACKGROUND: S-adenosylmethionine (SAMe) is a forerunner of glutathione. AIMS: The aim of the present study is to ascertain this drug effect on T-lymphocytes and cytokines in an experimental model of surgical sepsis. METHODS: Rats were allotted in two groups. In the control group, rats underwent anaesthesia and laparatomy with cecal ligation and puncture (CLP). In the second group, rats underwent the same CLP and received SAMe (14 mg/kg) i.m., on the 1st (1PO) and 2nd (2PO) postoperative days. A week before surgery (PRE), on the 1PO and on the 3PO: IL-1, IL-2, IL-4, IL-6, IL-10 and TNF levels (ELISA & MoAb), and CD3, CD4, CD8 cell and IL-2R percentages (%) (flow cytometry & MoAb) were determined in peripheral blood. RESULTS: Rats receiving SAMe do not show changes of CD3%, CD4% and IL-1 levels but show a significant increase of CD8% on the 3PO, showing a significant difference with regard to controls (p < 0.01). Both groups show a similar IL-2R variation pattern: increasing on 1PO (p < 0.05) and decreasing on 3PO (p < 0.05). CONCLUSION: In sepsis: SAMe inhibits the decrease of circulating immune-active cells and the IL-1 increase. This drug seems to have effects useful in avoiding immunological alterations in sepsis, that need to be tested in humans.

The increase in erythrocyte deformability in patients treated with nicardipine or nimodipine.

A study was made of a total of 50 patients, 36 females and 14 males, with an average age of 51.3 +/- 11.71 years (range 19-71). The group consisted of outpatients who came to the neurology clinic suffering from vascular headache or other symptomatic complaint of vascular type. In all cases, the existence of an organic neurological pathology had been considered and rejected. All patients who were smokers or suffering from hypertension were excluded, as well as those who had abnormal lipid or glucose values or who were on drug treatment for other reasons. The basal erythrocyte deformability value was determined and the patients divided into two random homogeneous groups. One of the groups was treated with nimodipine (90 mg/d) and the other with nicardipine (60 mg/d) for a period of two months. After this treatment period a further determination of the erythrocyte deformability was carried out. In the group treated with nimodipine, the erythrocyte deformability varied from 45.5 +/- 7.4 mcl/s to 50.35 +/- 12.02 mcl/s (p = 0.07123). In the group treated with nicardipine, these values varied from 45.96 +/- 7.35 mcl/s to 56.21 +/- 12.72 mcl/s (p = 0.00079). It was concluded that in both groups of patients, after two months treatment with these calcium antagonists, there was an improvement in erythrocyte deformability and, therefore, in blood fluidity, although only the nicardipine-treated group reached statistically significant levels.