Preoperative microbiologic screening and antibiotic prophylaxis in pulmonary resection operations.

BACKGROUND: Pulmonary resection is associated with considerable risk of infection, so antibiotic prophylaxis has become routine practice in pulmonary operations. We studied two standard flash antibiotic prophylaxis regimens and matched them to preoperatively acquired microorganisms. METHODS: In 120 patients scheduled for elective pulmonary resection, aspirates were taken separately from the left and the right lung using a double-lumen tube. Then the patients received either 1.5 g of sulbactam plus ampicillin (n = 60; group 1) or 2 g of cefazolin (n = 60; group 2) intravenously as a single-shot antibiotic prophylaxis according to a prospective randomized sequence. When bacteria were found in the aspirates, both antibiotics were tested for susceptibility. The patients were monitored for the first 3 postoperative days with regard to bronchopulmonary infections. RESULTS: Fifty-eight pathogens were isolated from the 120 patients. The cultured bacteria did not differ significantly between the two groups. In group 1 all found bacteria were susceptible to the used antibiotic prophylaxis, whereas in group 2 eight of the 25 found bacteria were not susceptible to antibiotic prophylaxis. Postoperatively, group 2 showed significantly more signs of bronchopulmonary infections than the group 1 and subsequently needed additional antibiotics more often. Intensive care unit stay was longer in patients of group 2 and costs were higher for these patients. CONCLUSIONS: Preoperative microbiologic examination could be helpful to evaluate efficacy of the antibiotic prophylaxis regimen. Sulbactam plus ampicillin was significantly more effective than cefazolin.

[Reduction of bacterial contamination during mechanical autotransfusion by uv irradiation--initial results]. / Reduktion von bakteriellen Kontaminationen während maschineller Autotransfusion durch UV-Bestrahlung--Erste Ergebnisse.

OBJECTIVE: To investigate the effects of UV-radiation of autologous blood on bacteria and red blood cells when using intraoperative sampling of autologous blood using a cell separator--an established method for reducing the need for donor blood during surgery--which is reported to have a bacterial contamination rate of 5-75%, due mainly to coagulase-negative staphylococci (CNS). METHODS: Cell-separator blood was diluted to a haematocrit level permitting transmission of 1% of the UV-radiation used in this study (lambda 254 nm, coat thickness 1 mm). CNS samples were irradiated for 2, 4, 10, 20 and 30 seconds. Free haemoglobin and methaemoglobin levels were measured, and erythrocytes examined microscopically at the end of the procedure. RESULTS: Blood samples had to be diluted to a haematocrit of 1% to permit transmission of 1% of the UV light. The optimal irradiation duration was 4 seconds, when bacteria were completely eliminated. Longer irradiation durations were associated with increasing levels of free haemoglobin and methaemoglobin, the levels of which at 4 seconds exposure were 12.5 mg/L and 15.5%, respectively. CONCLUSIONS: It is possible to prevent CNS contamination of cell-separator blood by irradiation with UV light. Prior to clinical application, however, the method will need to be modified to minimize side effects and increase its decontamination efficacy.

[Molecular basis for the pathogenicity of S. aureus alpha-toxins]. / Molekulare Grundlage für die Pathogenität des S.aureus-alpha-Toxins.

Staphylococcal alpha-toxin is produced by most strains of S. aureus and is considered a major pathogenic factor of these bacteria. The toxin is produced as a water-soluble molecule of MW 34000. Binding to a membrane target is accompanied by the formation of ring-structured hexamers with outer and inner diameters of 10 and 2-3 nm, respectively. The toxin rings carry lipid-binding surfaces that allow for insertion into and firm embedment within the membrane. Small transmembrane channels are thus generated that can induce a variety of pathological cellular changes. Large doses of toxin will generally cause cell lysis and death. However, sub-cytolytic toxin doses can also elicit major pathophysiological reactions. When introduced into the circulation of an isolated and perfused rabbit lung, the toxin causes steep rises in the pulmonary artery pressure, and lung edema results as a consequence of increases in vascular permeability occurring in parallel. These processes are the result of the activation of the arachidonic acid cascade by alpha-toxin in the lung. Studies using cultured endothelial cells as targets subsequently led to a hypothesis that would explain how membrane channel formation by a toxin could be linked to the observed arachidonic acid cascade activation. In essence, we propose that the toxin pores serve as non-physiological calcium channels, and that calcium influx triggers the observed reactions. It is probable that many other pathophysiological processes including inflammatory tissue reactions derive from such secondary effects of toxin action.(ABSTRACT TRUNCATED AT 250 WORDS)