In vitro activity of ertapenem against anaerobes isolated from the respiratory tract

Ertapenem is a novel parenteral carbapenem with a long serum half-life. Its spectrum of activity is similar to that of imipenem and meropenem against Gram-positive bacteria, Enterobacteriaceae and fastidious Gram-negative bacteria but it is less active against Pseudomonas aeruginosa and Acinetobacter spp. Several studies were performed in the United States but only one European study has shown that ertapenem has an excellent activity against anaerobes. The objectives of the present study were to test the activity of ertapenem against anaerobes isolated prospectively from the lower and upper respiratory tracts, and to compare their susceptibility with that of anaerobic isolates from other body sites. Fifty-three isolates from the respiratory tract, as well as 50 isolates from various other body sites were tested with E-tests against six antibiotics. For respiratory isolates and for isolates from other sites, MIC 90 values (mg/l) were, respectively, >32 and >32 for penicillin, 0.38 and 0.75 for amoxicillin/clavulanate, 48 and >256 for ceftriaxone, 0.12 and 0.75 for ertapenem, 12 and >256 for clindamycin and 2 and 12 for moxifloxacin. The higher susceptibility of respiratory tract isolates was mainly due to the different distribution of isolated species: only three respiratory isolates but 22 other isolates belonged to the Bacteroides fragilis group. This study confirms the excellent anti-anaerobic activity of ertapenem against anaerobic isolates from the respiratory tract.

Prevalence of fragilysin gene in Bacteroides fragilis isolates from blood and other extraintestinal samples

Of 166 Bacteroides fragilis isolates, 26.2% of 103 isolates from blood and 20.6% of 63 extraintestinal isolates harbored the fragilysin gene (difference not statistically significant). Clinical characteristics and evolution were comparable in patients with B. fragilis bacteremia with or without this enterotoxin. Fragilysin seems not to be an important virulence factor in B. fragilis disease.

Use of the E-test for determining antimicrobial susceptibility of anaerobic bacteria

Routine determination of antimicrobial susceptibility of anaerobic clinical isolates is difficult. The E-test is a practical alternative technique that we evaluated while testing clinical isolates in a multicenter study. The susceptibility to 9 antibiotics (penicillin, amoxycillin/clavulanate, ticarcillin/clavulanate, piperacillin/tazobactam, imipenem, cefoxitin, metronidazole, clindamycin, chloramphenicol) of 351 strains belonging to 63 different species was determined by the NCCLS reference agar dilution procedure using Wilkins-Chalgren agar medium with 5% sheep blood and was compared to the E-test performed on the same medium and using manufacturer's recommendations. The MIC values obtained with the E-test were generally one dilution lower than those obtained with the reference technique, 87.1% of the results being within two dilutions. In terms of susceptibility categories, 95.1% agreement was observed with 3.8% minor errors and only 0.5% major and 0.6% very major errors. With some Fusobacterium spp. and Clostridium spp. strains, the E-test was difficult to read or not interpretable because of the presence of growth within the inhibition zone of all beta-lactam antibiotics, representing a trailing phenomenon. We conclude that, if some interpretation difficulties are taken into account, the E-test is a convenient and reliable technique that can be applied in all clinical laboratories. It could be used for the individual testing of important anaerobes in certain clinical situations but cannot yet be considered as a reference technique. Its utility is emphasised by the increased resistance rate against clindamycin and the appearance of a few strains in the B. fragilis group with a reduced susceptibility against metronidazole.

In vitro activity of amoxycillin/clavulanate and ticarcillin/clavulanate compared with that of other antibiotics against anaerobic bacteria: comparison with the results of the 1987 survey

The activity of amoxycillin/clavulanate (Augmentin) and ticarcillin/ clavulanate (Timentin) was tested against 351 strict anaerobic clinical isolates collected from September 1993 to April 1994 in eight Belgian university hospitals and compared with that of 8 other antibiotics using the NCCLS reference agar dilution procedure. Production of beta-lactamase was detected by the nitrocefin test in 48% of the isolates. At NCCLS-recommended breakpoints, more than 90% of isolates were susceptible to amoxycillin/clavulanate, ticarcillin/clavulanate, piperacillin/tazobactam, imipenem, chloramphenicol and metronidazole but only 77%, 72% and 48% to cefoxitin, clindamycin and penicillin, respectively. In comparison with the results of a similar survey conducted in 1987 no major changes in susceptibility were observed except for the susceptibility to clindamycin that declined from 83% to 72% overall, and from 83% to 66% in the B. fragilis group. Furthermore one isolate of Clostridium clostridioforme was found produce beta-lactamase and few B. fragilis group isolates showed reduced susceptibility to metronidazole.

Clinical evaluation of the Bentley Univox membrane oxygenator

This paper reports a clinical evaluation of Bentley's new Univox membrane oxygenator (Bentley Laboratories, Irvine, California). In this new device, the blood flow path is outside the fibre, the incorporated heat exchanger consists of a 22-channel stainless-steel bellows, and the polypropylene fibres are woven into fibre ribbons and wound into each of the bellows channels. In this way, heat and gas transfers take place simultaneously. The priming volume has been reduced to 220ml and the membrane has an effective surface area of 1.6m 2. A BMR 1900 collapsible reservoir (Bentley Laboratories, Irvine, California) was used as a venous reservoir. Ten consenting patients undergoing elective coronary artery bypass surgery were perfused with this new oxygenator. BSA was between 1.7 and 2.11m 2; mean BSA was 1.81. Minimum priming was 1200 ml. The blood-gas results were all within or close to the normal range used in our institution. Acid-base management was performed using alpha-stat regulation and no problems occurred in this series of patients. Average pO 2 was 155mmHG+/-53 with a mean O 2 transfer of 90.7ml and a maximum of 185ml. The heat exchange performance was very good, with a mean coefficient of heat exchange of 0.54+/-0.11 and a maximum of 0.87.

In vitro activity of amoxycillin plus clavulanic acid and ticarcillin plus clavulanic acid compared with that of other antibiotics against anaerobic bacteria

The activity of amoxycillin/clavulanic acid (Augmentin) and ticarcillin/clavulanic acid (Timentin) was tested against 303 unselected clinical anaerobic isolates recently collected in seven Belgian university hospitals and compared with that of 11 other antimicrobial agents. Bacteroides spp. accounted for 52.1% of the isolates, Clostridium spp. for 23.4%, anaerobic cocci for 15.5%, nonsporeforming gram-positive bacilli for 4.6% and Fusobacterium spp. for 3.3%. Ticarcillin/clavulanic acid (fixed clavulanic acid concentration of 2 mg/l) was the most active drug with an overall susceptibility rate of 99.7%. Amoxycillin/clavulanic acid (fixed ratio of 2:1) and chloramphenicol inhibited 97.4% of the isolates, metronidazole 95.4%, piperacillin 92.4%, ticarcillin 91.4%, clindamycin 87.8%, cefotetan 81.2%, cefazolin 63.0%, cefuroxime 60.4%, erythromycin 57.8%, penicillin 57.1% and doxycycline 52.1%. beta-lactamases were detected exclusively in Bacteroides spp. isolates (79.1% positive).

Addition of nitrous oxide to fentanyl anesthesia does not induce myocardial ischemia in patients with ischemic heart disease

Although nitrous oxide is commonly administered to patients with ischemic heart disease, recent reports suggest that it may induce myocardial ischemia in these patients. The authors compared the effects of nitrous oxide on segmental left ventricular (LV) function and the ST segment of the electrocardiogram with the effects of an equal concentration of nitrogen (crossover design) before the start of surgery in 18 patients who required coronary-artery bypass grafting. The patients studied did not have valvular or LV dysfunction. Anesthesia was induced and maintained with intravenous fentanyl. After endotracheal intubation and 20 min of ventilation with 100% oxygen, either 60% nitrous oxide or 60% nitrogen (randomly assigned) was added to the inspired gas mixture of each patient for 10 min. This was followed by 10 min of 100% oxygen, and then 10 min of 60% nitrous oxide or 60% nitrogen, whichever had not been administered previously. Patients were monitored for myocardial ischemia using a standard 12-lead electrocardiogram and trans-esophageal two-dimensional echocardiography. Surgery did not begin until the study was concluded. No patient experienced an ST segment change greater than 1 mm during the study, and none developed a new segmental wall motion abnormality during inhalation of either nitrous oxide or nitrogen. The authors conclude that nitrous oxide does not induce myocardial ischemia when used as an adjunct to fentanyl anesthesia in patients who have severe coronary-artery disease accompanied by well-preserved valvular and LV function.

A retrospective study of 130 consecutive multiple trauma patients in an intensive care unit

A retrospective study of 130 multiple trauma patients admitted to an intensive care unit is presented. Overall mortality was 33% for a mean ISS of 39.4. Craniocerebral trauma, multiple organ failure, sepsis and ARDS are the main causes of death, although there is no statistical difference for these between survivors and non-survivors. There is a good correlation between ISS and mortality (r = 0.86). Patients developing MOF, sepsis and ARDS have significantly higher ISS. Mortality from complications such as sepsis, MOF, ARDS and aspiration pneumonia seems more related to age.

A hemodynamic study of epidural versus intravenous anesthesia for aortofemoral bypass surgery

The hemodynamic effects of two types of anesthesia on aortofemoral bypass surgery were studied in a randomised prospective trial. Epidural anesthesia supplemented with nitrous oxide (group I) and total intravenous anesthesia combining fentanyl and a continuous infusion of etomidate (group II) were compared. A high incidence of preoperative disease was found and all 18 patients were classified in ASA classes III-IV. It is concluded that epidural anesthesia provides excellent anesthetic and hemodynamic stability provided that an optimal filling pressure is maintained. Total intravenous anesthesia resulted in significant hypertensive reactions during surgery, which were not specifically related to crossclamping. Decreasing the high SVRI with vasodilatory treatment was necessary to treat hypertension in all those patients with preoperative hypertensive disease. No problems were seen in the intravenous group patients without preoperative hypertension. Cardiac work was higher in the intravenous group due to the high impedance of the cardiovascular system provoked by the absence of vasodilatory properties with this type of intravenous anesthesia. Monitoring of PWP and CI by Swan-Ganz catheter is shown to be very useful for optimalization of hemodynamics and fluid management especially during crossclamping, when normal Frank-Starling relationships might not be valid anymore. The effect of vasodilatory treatment, crossclamping and declamping could be carefully evaluated.

Halothane treatment in life-threatening asthma

We analysed the case histories of 22 patients with life threatening asthma retrospectively. Fifteen patients needed mechanical ventilation. Three patients, all of them in cardiac arrest before or at the moment of admission, died. In five patients, halothane therapy was successfully used as a last resort. No major complications occurred. Two case-reports are presented.