Treatment of hospitalized patients with complicated gram-positive skin and skin structure infections: two randomized, multicentre studies of quinupristin/dalfopristin versus cefazolin, oxacillin or vancomycin. Synercid Skin and Skin Structure Infection Group

Quinupristin/dalfopristin (Synercid), the first injectable streptogramin antibiotic available for the treatment of complicated gram-positive skin and skin structure infections, was compared with standard comparators (cefazolin, oxacillin or vancomycin) in one USA and one international trial. These two randomized, open-label trials of virtually identical design enrolled a total of 893 patients (450 quinupristin/dalfopristin, 443 comparator). The majority of patients had erysipelas, traumatic wound infection or clean surgical wound infection. Staphylococcus aureus was the most frequently isolated pathogen in both treatment groups and polymicrobial infection was more common in the quinupristin/dalfopristin group than in the comparator group. The clinical success rate (cure plus improvement) in the clinically evaluable population was equivalent between the two treatment groups (68.2% quinupristin/dalfopristin, 70.7% comparator; 95% CI, -10.1, 5.1) despite a shorter mean duration of treatment for quinupristin/dalfopristin patients. In the bacteriologically evaluable population, by-patient and by-pathogen bacteriological eradication rates were somewhat lower for quinupristin/dalfopristin (65.8% and 66.6%, respectively) than for the comparator regimens (72.7% and 77.7%, respectively). The lower bacteriological response rates in the quinupristin/dalfopristin group were, in part, due to a higher rate of polymicrobial infections and a higher incidence of patients classified as clinical failure, a category which included premature discontinuation of treatment because of local venous adverse events. The bacteriological eradication rate for quinupristin/dalfopristin was higher in monomicrobial infections than in polymicrobial infections (72.6% versus 63.3%, respectively), whereas the corresponding rate for the comparator regimens was lower for monomicrobial infections than polymicrobial infections (70.8% versus 83.1%). This finding was not unexpected, since the spectrum of quinupristin/dalfopristin is focused on gram-positive pathogens and additional antibiotics to treat gram-negative bacteria were not required per protocol. The systemic tolerability of both treatment regimens was qualitatively similar. A higher rate of drug-related venous adverse events was reported for quinupristin/dalfopristin (66.2%) than for the comparator regimen (28.4%). Premature discontinuation of study drug was primarily due to adverse clinical events for quinupristin/dalfopristin (19.1%), whereas the most common reason for discontinuation among those receiving the comparator regimens was treatment failure (11.5%). Quinupristin/dalfopristin is an effective alternative for the treatment of hospitalized patients with complicated skin and skin structure infections due to quinupristin/ dalfopristin-susceptible gram-positive organisms, including methicillin- and erythromycin-resistant S. aureus.

A comparison of serial plate agar dilution, Bauer-Kirby disk diffusion, and the Vitek AutoMicrobic system for the determination of susceptibilities of Klebsiella spp., Enterobacter spp., and Pseudomonas aeruginosa to ten antimicrobial agents

The use of rapid, automated technologies for assessment of antimicrobial susceptibility and determination of minimum inhibitory concentrations has been evolving for over a decade. We compared the Vitek AutoMicrobic system and Bauer-Kirby disk diffusion with the National Committee for Clinical Laboratory Standards methods of serial plate agar dilution for qualitative and quantitative susceptibilities of 301 hospital isolates of Klebsiella spp., Enterobacter spp., and Pseudomonas aeruginosa. Antibiotics tested were aztreonam, cefoperazone, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, piperacillin, ticarcillin-clavulanic acid, and tobramycin. Agar dilution and Bauer-Kirby results were more strongly correlated for all three genera than were the results for agar dilution and Vitek. If agar dilution is presumed to be the "gold standard," Bauer-Kirby disk diffusion had only half the number of false susceptibles as did the Vitek. Thus, the Vitek AutoMicrobic system seems to be somewhat less reliable for both qualitative and quantitative measurement of susceptibility and resistance than is Bauer-Kirby disk diffusion.

Antibiotic prophylaxis for cardiothoracic operations. Meta-analysis of thirty years of clinical trials

Antistaphylococcal penicillins and first-generation cephalosporins have traditionally been the prophylactic antibiotics of choice for patients undergoing cardiothoracic operations. Recently published studies have claimed improved outcomes with respect to postoperative wound infection when second-generation cephalosporins were used for prophylaxis. The purpose of this study was to critically review the infectious outcomes of prospective, randomized, and controlled studies of cardiothoracic surgery prophylaxis by means of meta-analytic techniques. For each of 28 studies meeting the meta-analysis entry criteria, odds ratios with 95% confidence intervals were calculated to compare the prophylactic efficacy of the antibiotic regimens. Odds ratios were then pooled, and a summary odds ratio was calculated for each pairing of antibiotic treatments. Placebo-controlled trials of cardiothoracic prophylaxis demonstrated a consistent benefit to the administration of antibiotic prophylaxis, with an approximate fivefold reduction in wound infection rate. The second-generation cephalosporins, cefamandole and cefuroxime, performed better than cefazolin, with an approximate one and one-half-fold reduction in wound infection rate. Administration of prophylaxis beyond 48 hours was not associated with improved infectious outcomes.

Cost-analysis of imipenem-cilastatin monotherapy compared with clindamycin+aminoglycoside combination therapy for treatment of serious lower respiratory, intra-abdominal, gynecologic, and urinary tract infections

To determine the cost relative to efficacy and tolerability of two antimicrobial regimens, a prospective, multicenter study compared imipenem-cilastatin (I-C) monotherapy with clindamycin+aminoglycoside (C+A) in the treatment of serious lower respiratory, intra-abdominal, gynecologic, and urinary tract infections. The costs of acquiring, preparing, administering, and monitoring both regimens were obtained for 350 (99.4%) of 352 patients evaluated for efficacy; 170 were treated with I-C and 182 with C+A. Average acquisition costs per patient course of study antibiotic therapy were higher for I-C than for C+A (mean, $329 vs $119, respectively; P = 0.0001). This was offset, however, by greater costs in the C+A group for dosage preparation, material and labor, and need for therapeutic drug monitoring of the aminoglycoside. In addition, a greater proportion of patients failed C+A therapy than I-C therapy, leading to increased costs relating to extended hospitalization and subsequent antimicrobial therapy. Overall, the average total cost per patient course of study antibiotic therapy was numerically but not statistically lower for the I-C group than for the C+A group ($507 vs $813, respectively).

Efficacy and tolerability of imipenem-cilastatin versus clindamycin+gentamicin for serious pelvic infections

A multicenter, prospective, open-label, randomized trial compared imipenem-cilastatin (I-C) monotherapy with the combination of clindamycin+gentamicin (C+G). Efficacy and tolerability in the treatment of serious pelvic infections were evaluated in 94 female patients with acute salpingitis, pelvic abscess, or postoperative pelvic cellulitis. Duration of therapy averaged 5.4 days for treatment successes and ten days for treatment failures. The overall treatment success rate was 98% (43 of 44 patients) in the I-C group, compared with 92% (46 of 50 patients) in the C+G group (P = NS). Adjunct therapy for two treatment successes in the I-C group included laparoscopy and surgical removal of a pelvic abscess without change in antibiotics. Both I-C and C+G were highly effective and generally well tolerated for the treatment of salpingitis, pelvic abscess, and postoperative pelvic cellulitis.