Utilization of Colistin Versus β-Lactam and β-Lactamase Inhibitor Agents in Relation to Acute Kidney Injury in Patients with Severe Gram-Negative Infections

Introduction

Colistin is used to treat severe antibiotic-resistant Gram-negative infections (GNIs). With the rise of antibiotic resistance, colistin has been used increasingly as a ‘last-line’ therapy for multidrug-resistant GNIs. We evaluated the incidence of acute kidney injury (AKI) and mortality among patients receiving colistin or one of the new β-lactam/β-lactamase inhibitors (βL + βLI) (ceftazidime/avibactam, ceftolozane/tazobactam, or meropenem/vaborbactam).

Methods

This retrospective cohort study used data from the Premier Healthcare Database. The cohort included propensity score-matched adults with an inpatient stay between January 2016 and December 2018. Patients given both colistin and BL + BLI as treatment for ≥ 72 h were excluded. AKI was defined as acute renal failure or dialysis during hospitalization with antibiotic administration. Propensity score matching was used to control for selection bias and confounding. Logistic regression evaluated associations between treatment, AKI, and in-hospital mortality.

Results

The total number of patients in the matched cohorts were 256 in each. Overall, 23.8% and 13.3% of patients receiving colistin or new βL + βLI agents, respectively, experienced AKI during hospitalization (p = 0.002); odds of AKI for colistin were 3.0 (95% CI 1.71, 5.21). Following propensity score-matching, patients without baseline renal disease experienced AKI during hospitalization to a higher degree in the colistin group compared to the βL + βLI group (17.1% vs. 6.8%); colistin use was associated with 3.7 times higher odds (95% CI 1.84, 7.42) of AKI compared to βL + βLI agents. The odds of mortality in patients on colistin developing AKI were more than three times that of patients receiving a BL + BLI agent who developed AKI. Among patients receiving colistin, incident AKI was associated with 6.1 times higher odds (95% CI 2.53, 14.71) of mortality.

Conclusions

Patients receiving colistin for GNIs had significantly higher odds of AKI and mortality than those receiving βL + βLI.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40121-021-00556-x.

Designing A Pathogen-Focused Study To Address The High Unmet Medical Need Represented By Carbapenem-Resistant Gram-Negative Pathogens - The International, Multicenter, Randomized, Open-Label, Phase 3 CREDIBLE-CR Study

Carbapenem-resistant (CR) Gram-negative infections, including those caused by Enterobacteriaceae and the non-fermenters, represent the greatest unmet need for new effective treatments. The clinical development of new antibiotics for the treatment of CR infections is challenging and should focus on the individual pathogens irrespective of the infection site. However, the drug approval pathway is generally infection-site specific and rarely includes such drug-resistant pathogens. To overcome this limitation, a streamlined clinical development program may include a pathogen-focused clinical study, such as the CREDIBLE-CR study, to meet the expectations of some health authorities (ie, the European Medicines Agency [EMA]) and the medical community. Cefiderocol is a novel siderophore cephalosporin designed to target CR pathogens, including CR strains of Enterobacteriaceae (CRE), Pseudomonas aeruginosa, Acinetobacter baumannii, and also Stenotrophomonas maltophilia, which is intrinsically CR. The CREDIBLE-CR study was planned to evaluate cefiderocol in patients with CR Gram-negative infections regardless of species or infection-site source. Rapid diagnostic testing and/or selective media were provided to facilitate detection of CR pathogens to rapidly enroll patients with nosocomial pneumonia, bloodstream infection/sepsis, or complicated urinary tract infection. Patients were randomized 2:1 to receive cefiderocol or best available therapy. There were no pre-specified statistical hypotheses for this study, as the sample size was driven by enrollment feasibility and not based on statistical power calculations. The objective of the CREDIBLE-CR study was to provide descriptive evidence of the efficacy and safety of cefiderocol for the target population of patients with CR infections, including the non-fermenters. The CREDIBLE-CR study is currently the largest pathogen-focused, randomized, open-label, prospective, Phase 3 clinical study to investigate a new antibiotic in patients with CR Gram-negative infections. Here we describe the design of this pathogen-focused study and steps taken to aid patient enrollment into the study within an evolving regulatory environment.

Progress in the Fight Against Multidrug-Resistant Bacteria 2005-2016: Modern Noninferiority Trial Designs Enable Antibiotic Development in Advance of Epidemic Bacterial Resistance

From a public health perspective, new antibacterial agents should be evaluated and approved for use before widespread resistance to existing agents emerges. However, for multidrug-resistant pathogens, demonstration of superior efficacy of a new agent over a current standard-of-care agent is routinely feasible only when epidemic spread of these dangerous organisms has already occurred. One solution to enable proactive drug development is to evaluate new antibiotics with improved in vitro activity against MDR pathogens using recently updated guidelines for active control, noninferiority trials of selected severe infections caused by more susceptible pathogens. Such trials are feasible because they enroll patients with infections due to pathogens with a "usual drug resistance" phenotype that will be responsive to widely registered standard-of-care comparator antibiotics. Such anticipatory drug development has constructively reshaped the antibiotic pipeline and offers the best chance of making safe and efficacious antibiotics available to the public ahead of epidemic resistance.

A long and winding road; evolution of antimicrobial drug development - crisis management

The development of antimicrobial drugs has evolved from observational case reports to complex randomized prospective clinical trials in specific treatment indications. Beginning around the year 2000, the US FDA has evolved its approach on study design and other study characteristics, which has made the conduct of these studies more difficult and the outcomes for sponsors more risky. This has contributed to the decline in the discovery and development of new antimicrobials, which are needed to address the increasing problem of bacterial resistance to existing marketed products. This study reviews the historical basis for the current regulatory climate including the various crises that have led to considerable political pressures on the agency. Recent efforts to resolve development uncertainties and to provide economic incentives for future antimicrobial drug development are presented.

Clinical trial design and consequences for drug development for community-acquired pneumonia: an industry perspective

Antibiotic development has decreased significantly, in part because of recent changes in regulatory requirements in the United States. These changes both decrease the probability of technical and regulatory success for a new antibiotic for which marketing approval is sought and motivate the pharmaceutical industry to focus its research efforts on other therapeutic areas. There is a growing, unmet clinical need for new antibiotics, because of bacterial resistance to approved drugs; however, there are few candidates in development, especially new oral agents for treatment of community-acquired respiratory infections. The answers to important questions about the benefit of antibacterial treatment for community-acquired pneumonia and the publication of clear guidance for future clinical studies will support future investments. We discuss the underlying issues and offer some alternative strategies to enable improvements in clinical trial design for community-acquired pneumonia.

Activity of faropenem against middle ear fluid pathogens from children with acute otitis media in Costa Rica and Israel

Faropenem was tested against 1,188 middle ear fluid pathogens from children in Israel and Costa Rica. Against Streptococcus pneumoniae and Haemophilus influenzae, faropenem was the most active beta-lactam, with activity that was similar to or greater than of the other oral antimicrobial classes studied. Faropenem was also active against Moraxella catarrhalis and Streptococcus pyogenes.

Faropenem medoxomil: a treatment option in acute bacterial rhinosinusitis

Faropenem medoxomil is the first oral penem in a new class of beta-lactam antibiotics. Faropenem medoxomil has excellent in vitro activity against Streptococcus pneumoniae, Haemophilus influenzae and other key pathogens implicated in acute bacterial rhinosinusitis. Clinical studies have demonstrated that, in the treatment of acute bacterial rhinosinusitis in adults, 7 days of treatment with faropenem medoxomil is as clinically and bacteriologically effective as 10 days of treatment with cefuroxime axetil. One study showed faropenem medoxomil to be superior to cefuroxime axetil. Overall, the safety profile of faropenem medoxomil is similar to that of most comparators. Specifically, the minimal impact of faropenem medoxomil on the gastrointestinal flora leads to less diarrhea and other adverse events than coamoxicillin-clavulanate. Faropenem medoxomil has almost no drug-drug interactions and little requirement for dosage adjustments in the typical acute rhinosinusitis population.

Bacteriologic and clinical efficacy of oral gatifloxacin for the treatment of recurrent/nonresponsive acute otitis media: an open label, noncomparative, double tympanocentesis study

BACKGROUND

Gatifloxacin is an 8-methoxyfluoroquinolone with good activity against respiratory pathogens.

OBJECTIVES

To document the bacteriologic and clinical efficacy of gatifloxacin in recurrent/nonresponsive acute otitis media (AOM).

METHODS

One hundred sixty patients 6 to 48 months of age with recurrent/nonresponsive AOM received gatifloxacin suspension (10 mg/kg once daily for 10 days). Recurrent AOM was defined as > or =3 AOM episodes during the previous 6 months or > or =4 AOM episodes during the previous 12 months. Nonresponsive AOM was defined as AOM occurring < or =14 days after completing antibiotic treatment or not improving after > or =48 h of therapy. Middle ear fluid (MEF) obtained by tympanocentesis pretreatment (Day 1) and 3 to 5 days after initiation of treatment (Days 4 to 6) was cultured. Additional MEF cultures were obtained if clinical failure or recurrence of AOM occurred. Bacteriologic failure was defined by culture-positive MEF during treatment. Patients were followed until Days 22 to 28. Susceptibility was determined by broth microdilution.

RESULTS

One hundred twenty-eight (80%) patients completed treatment, and 32 discontinued the study prematurely (adverse events, 17; lost to follow-up, 10; consent withdrawal, 3; and laboratory abnormalities, 2). From 89 patients (median age, 1 year; median number of prior AOM episodes, 4; range, 0 to 12), 121 pathogens were recovered: Haemophilus influenzae, 74 (61%); Streptococcus pneumoniae, 36 (30%); Moraxella catarrhalis, 9 (7%); and Streptococcus pyogenes, 2 (2%). The 36 S. pneumoniae isolates were susceptible to gatifloxacin (MIC50 0.25 microg/ml); 26 of 36 (72%) were penicillin-nonsusceptible (15 fully resistant). All 74 H. influenzae isolates were susceptible to gatifloxacin (MIC < or = 0.03 mg/ml). Fourteen of 74 (19%) and 9 of 9 (100%) H. influenzae and M. catarrhalis isolates, respectively, produced beta-lactamase. Bacteriologic eradication was achieved for 118 of 121 (98%) pathogens: 74 of 74 H. influenzae; 34 of 36 (94%) S. pneumoniae; 9 of 9 M. catarrhalis; and 1 of 2 S. pyogenes. Clinical improvement/cure at end of treatment was seen in 103 of 114 (90%) clinically evaluable patients. Clinical recurrence of AOM after completion of therapy occurred in 31 patients. Of the 27 recurrent AOM cases in which tympanocentesis was performed, there were 16 (59%) new infections, 4 (15%) culture-negative results and only 7 (26%) true bacteriologic relapses. Adverse events were recorded in 21 of 160 (13%) patients: vomiting, 16; diarrhea, 3; maculopapular rash, 2. No articular adverse events were recorded.

CONCLUSION

Gatifloxacin is efficacious and safe for the treatment of recurrent/nonresponsive AOM.

Demographic, clinical, and treatment parameters influencing the outcome of acute cystitis

A meta-analysis of six double-blinded clinical trials was undertaken to identify risk factors associated with bacteriologic outcome in 3,108 women with acute cystitis. Eleven antibiotic regimens were used, including ciprofloxacin, ofloxacin, norfloxacin, trimethoprim-sulfamethoxazole, and nitrofurantoin. Entry criteria for all studies were identical. Among 2,409 patients who were defined to be valid for efficacy analysis, pathogens included Escherichia coli (78.6%), Staphylococcus saprophyticus (4.4%), Klebsiella pneumoniae (4.3%), Proteus mirabilis (3.7%), and "other" (9%). Causative bacteria were eradicated at the end of treatment in 93% of patients. The following parameters were associated with successful bacteriologic outcome: not using a diaphragm (P = .0041), treatment for > or = 3 days (P = .0043), pathogen not "other" (P = .0043), symptom duration of < 2 days (P = .0096), and African American race (P = .0147). K. pneumoniae (P = .0496) and "other" pathogens (P = .0018) were associated with increased probability of bacteriologic treatment failure. The presence of pyuria (> or = 10 WBCs per high-power field) did not correlate with outcome and was inversely correlated with the finding of > or = 10(5) bacterial colony-forming units per mL of urine (P < .001). This large database identifies new parameters associated with treatment outcomes of acute cystitis and calls into question current clinical trial guidelines.

Double-blind comparative trial of ciprofloxacin versus clarithromycin in the treatment of acute bacterial sinusitis. Sinusitis Infection Study Group

This multicenter, randomized, double-blind trial compared the efficacy and safety of ciprofloxacin (CIP; 500 mg twice daily for 10 days, placebo for 4 days) to those of clarithromycin (CLARI; 500 mg twice daily for 14 days) in 560 adults with clinically documented and radiologically confirmed acute sinusitis. Of 457 efficacy-valid adults (236 CIP, 221 CLARI), clinical resolution plus improvement at the end of therapy was 84% for CIP-treated patients compared to 91% of CLARI recipients (CI95 = -0.131, -0.013). At the 1-month follow-up, more than twice as many CLARI-treated patients, 18 (10%), experienced a relapse, compared to 7 (4%) CIP-treated patients. The combined clinical response analyses (end of therapy and 1 -month follow-up) demonstrated that CIP and CLARI were statistically equivalent (CI95 = -0.106, 0.044). Diarrhea, nausea, headache, and dizziness were the most frequently reported drug-related adverse events in both treatment groups; diarrhea and taste perversion were reported more frequently among CLARI recipients. In summary, the combined end of therapy and follow-up clinical evaluation analyses revealed that CIP and CLARI were equally effective in the management of acute sinusitis, although twice as many relapses were reported among CLARI recipients.

Single-dose oral ciprofloxacin compared with cefotaxime and placebo for prophylaxis during transurethral surgery

To determine the efficacy and safety of single-dose oral ciprofloxacin prophylaxis for the prevention of post-operative bacteriuria following transurethral resection of the prostate or bladder tumour, a prospective, randomized, double-blind, placebo-controlled trial was conducted. Five hundred and eighteen patients were randomized in a 2:2:1 ratio to receive ciprofloxacin 500 mg, cefotaxime 1 g or placebo 30-90 min before surgery. Of the 368 efficacy-evaluable patients, five (3.3%) ciprofloxacin, seven (4.8%) cefotaxime and five (7.0%) placebo recipients had post-operative bacteriuria (> or = 10(4) cfu/mL) during post-operative days 2-15. Five (3.4%) ciprofloxacin, five (3.4%) cefotaxime and one (2.4%) placebo recipients were considered clinical failures, of whom one, two and one patients, respectively, had concomitant bacteriuria. Drug-related adverse events were reported in six of 204 (3%) ciprofloxacin, 12 of 197 (6%) cefotaxime and one of 101 (1%) placebo patients. The observed rates of post-operative bacteriuria suggest that a single 500 mg dose of ciprofloxacin is suitable prophylaxis for transurethral surgery.

A randomized trial of short-course ciprofloxacin, ofloxacin, or trimethoprim/sulfamethoxazole for the treatment of acute urinary tract infection in women. Ciprofloxacin Urinary Tract Infection Group

PURPOSE

Bladder infections are very common in otherwise healthy women, and short-course antimicrobial treatment appears effective for many episodes of cystitis. This study reports the results of short-course ciprofloxacin, ofloxacin, and trimethoprim/sulfamethoxazole therapy.

PATIENTS AND METHODS

We performed a randomized, double-blind study of the efficacy and safety of a 3-day course of oral ciprofloxacin 100 mg twice daily, ofloxacin 200 mg twice daily, or trimethoprim/sulfamethoxazole 160/800 mg twice daily in women with acute, uncomplicated, symptomatic lower urinary tract infection.

RESULTS

A total of 866 patients were enrolled, of whom 688 (79%) were evaluated for the efficacy of treatment (229 treated with ciprofloxacin, 228 treated with trimethoprim/sulfamethoxazole, and 231 treated with ofloxacin). The most frequent reason for exclusion was the failure to identify a pretreatment pathogen. The most commonly isolated pathogen was Escherichia coli (81%). Eradication of the pretreatment pathogen at the end of therapy occurred in 94% of ciprofloxacin, 93% of trimethoprim/sulfamethoxazole, and 97% of ofloxacin-treated patients. At follow-up evaluation at 4 to 6 weeks, recurrence rates (relapse or reinfection) were 11% in the ciprofloxacin, 16% in the trimethoprim/sulfamethoxazole, and 13% in the ofloxacin treatment group. Clinical success at the end of therapy was 93% in the ciprofloxacin, 95% in the trimethoprim/sulfamethoxazole, and 96% in the ofloxacin treatment groups. The frequency of all adverse events was 31% for ciprofloxacin, 41% for trimethoprim/sulfamethoxazole, and 39% for ofloxacin-treated patients (P = 0.03). Premature discontinuation of study drug due to an adverse event was more common in trimethoprim/sulfamethoxazole-treated patients (n = 9) compared with those given ciprofloxacin (n = 2) or ofloxacin (n = 1; P = 0.02).

CONCLUSION

Ciprofloxacin, ofloxacin, and trimethoprim/sulfamethoxazole had similar efficacy when given for 3 days to treat acute, symptomatic, uncomplicated lower urinary tract infection in women.

A trial comparing low-dose, short-course ciprofloxacin and standard 7 day therapy with co-trimoxazole or nitrofurantoin in the treatment of uncomplicated urinary tract infection

The study was undertaken to compare the safety and efficacy of twice-daily ciprofloxacin for 3 days with standard 7 day therapy with either co-trimoxazole or nitrofurantoin in the treatment of women with acute, uncomplicated urinary tract infections (UTI). This multicentre, prospective, randomized, double-blind trial compared oral ciprofloxacin (100 mg bd) for 3 days with co-trimoxazole (160/800 mg bd) or nitrofurantoin (100 mg bd) for 7 days. Bacteriological and clinical evaluations were performed at study entry, during therapy and 4-10 days and 4-6 weeks after the completion of therapy. The primary efficacy parameter was eradication of the causative organism 4- 10 days following treatment. Of 713 women enrolled and evaluable for safety, 521 were evaluable for efficacy (168 ciprofloxacin, 174 co-trimoxazole, 179 nitrofurantoin). Escherichia coli (83%) was the most frequently isolated pathogen in all treatment groups. Bacteriological eradication was reported in 88% of ciprofloxacin patients, 93% of co-trimoxazole patients and 86% of nitrofurantoin patients. At the 4-6 week follow-up, ciprofloxacin had statistically significantly higher eradication rates (91%) than co-trimoxazole (79%; 95% confidence limit (CL) = −20.6%, −3.9%) and nitrofurantoin (82%; 95% CL = −17.1%, −0.9%). Clinical resolution 4- 10 days after therapy and at the 4- 6 week follow-up was similar among the three treatment groups. The overall incidence of treatment-emergent adverse events was not significantly different (P= 0.093) among the three drug regimens, althousgh co-trimoxazole was associated with a greater number of adverse events than ciprofloxacin (P ≤0.05). Ciprofloxacin also caused fewer episodes of nausea than either of the other agents (P ≤0.01).

A trial comparing low-dose, short-course ciprofloxacin and standard 7 day therapy with co-trimoxazole or nitrofurantoin in the treatment of uncomplicated urinary tract infection

The study was undertaken to compare the safety and efficacy of twice-daily ciprofloxacin for 3 days with standard 7 day therapy with either co-trimoxazole or nitrofurantoin in the treatment of women with acute, uncomplicated urinary tract infections (UTI). This multicentre, prospective, randomized, double-blind trial compared oral ciprofloxacin (100 mg bd) for 3 days with co-trimoxazole (160/800 mg bd) or nitrofurantoin (100 mg bd) for 7 days. Bacteriological and clinical evaluations were performed at study entry, during therapy and 4-10 days and 4-6 weeks after the completion of therapy. The primary efficacy parameter was eradication of the causative organism 4-10 days following treatment. Of 713 women enrolled and evaluable for safety, 521 were evaluable for efficacy (168 ciprofloxacin, 174 co-trimoxazole, 179 nitrofurantoin). Escherichia coli (83%) was the most frequently isolated pathogen in all treatment groups. Bacteriological eradication was reported in 88% of ciprofloxacin patients, 93% of co-trimoxazole patients and 86% of nitrofurantoin patients. At the 4-6 week follow-up, ciprofloxacin had statistically significantly higher eradication rates (91%) than co-trimoxazole (79%; 95% confidence limit (CL) = -20.6%, -3.9%) and nitrofurantoin (82%; 95% CL = -17.1%, -0.9%). Clinical resolution 4-10 days after therapy and at the 4-6 week follow-up was similar among the three treatment groups. The overall incidence of treatment-emergent adverse events was not significantly different (P = 0.093) among the three drug regimens, although co-trimoxazole was associated with a greater number of adverse events than ciprofloxacin (P < or = 0.05). Ciprofloxacin also caused fewer episodes of nausea than either of the other agents (P < or = 0.01).

Single-dose oral ciprofloxacin compared with cefotaxime and placebo for prophylaxis during transurethral surgery

To determine the efficacy and safety of single-dose oral ciprofloxacin prophylaxis for the prevention of post-operative bacteriuria following transurethral resection of the prostate or bladder tumour, a prospective, randomized, double-blind, placebo-controlled trial was conducted. Five hundred and eighteen patients were randomized in a 2:2:1 ratio to receive ciprofloxacin 500 mg, cefotaxime 1 g or placebo 30- 90 min before surgery. Of the 368 efficacy-evaluable patients, five (3.3%) ciprofloxacin, seven (4.8%) cefotaxime and five (7.0%) placebo recipients had post- operative bacteriuria (≥10 4 cfu/mL) during post-operative days 2- 15. Five (3.4%) ciprofloxacin, five (3.4%) cefotaxime and one (2.4%) placebo recipients were considered clinical failures, of whom one, two and one patients, respectively, had concomitant bacteriuria. Drug-related adverse events were reported in six of 204 (3%) ciprofloxacin, 12 of 197 (6%) cefotaxime and one of 101 (1%) placebo patients. The observed rates of post-operative bacteriuria suggest that a single 500 mg dose of ciprofloxacin is suitable prophylaxis for transurethral surgery.

Ciprofloxacin versus cefuroxime axetil in the treatment of acute bacterial sinusitis. Sinusitis Infection Study Group

OBJECTIVE

This study was conducted to compare the efficacy and safety of ciprofloxacin to cefuroxime axetil for the management of acute bacterial sinusitis or acute exacerbations of chronic sinusitis.

METHOD

In this prospective, multicentre, randomized, double-blind clinical trial, 501 adult outpatients seen in 17 otolaryngology offices with both symptoms and radiographic evidence of acute maxillary sinusitis randomly received oral ciprofloxacin (500 mg b.i.d.) or cefuroxime axetil (250 mg b.i.d.), each for 10 days. Patients were further subclassified as having either acute sinusitis or an acute exacerbation of chronic sinusitis. All patients underwent maxillary sinus aspiration at study entry to establish a microbiologic etiology. The primary measure of efficacy was the rate of clinical success in the efficacy-valid population at the end of therapy. Secondary measures included bacteriologic response at the end of therapy, and 2- to 4-week clinical and bacteriologic follow-up response rates in both efficacy-valid and intent-to-treat groups.

RESULTS

Haemophilus influenzae (21%), Streptococcus pneumoniae (19%), Moraxella catarrhalis (14%), and Staphylococcus aureus (9%) were the most commonly isolated pathogens (target organisms) among the 225 causative organisms identified from 189 patients. Of 453 adults valid for clinical efficacy (228 ciprofloxacin, 225 cefuroxime axetil), ciprofloxacin treatment was statistically equivalent to cefuroxime axetil at the end of treatment (87% vs. 83%; CI95 = -0.021 ... 0.106) and at follow-up (91% vs. 88%; CI95 = -0.044 ... 0.080). The clinical response was similar for subgroups of patients with positive cultures, including the subset with target organisms. Bacteriologic eradication at end of therapy was similar between the two groups (97% ciprofloxacin, 95% cefuroxime axetil). Both treatments were equally well tolerated.

CONCLUSION

Ciprofloxacin is as effective as cefuroxime axetil in the treatment of community-acquired acute sinusitis.

Single-dose oral ciprofloxacin versus placebo for prophylaxis during transrectal prostate biopsy

OBJECTIVES

To determine whether antimicrobial prophylaxis could prevent infections after transrectal needle biopsy of the prostate using automated biopsy devices.

METHODS

We conducted a prospective, randomized, double-blind, multicenter trial in which a total of 537 patients received either oral ciprofloxacin 500 mg or placebo before transrectal needle biopsy of the prostate. Repeated urine cultures and urinalysis were obtained at 2 to 6 days after biopsy and 9 to 15 days after biopsy. The primary determinant of efficacy was bacteriologic response (bacteriuria [more than 10(4) colony-forming units (CFU)/mL] versus no bacteriuria) at the 9- to 15-day follow-up evaluation.

RESULTS

Two hundred twenty-seven (84%) of 269 ciprofloxacin patients and 230 (86%) of 268 placebo patients were valid for efficacy analysis in which a mean of four biopsies was performed. Six ciprofloxacin-treated (3%) and 19 placebo-treated (8%) patients had bacteriuria (more than 10(4) CFU/mL) after the procedure (P = 0.009). Six ciprofloxacin recipients (3%) and 12 placebo recipients (5%) had clinical signs and symptoms of a urinary tract infection (UTI) (P = 0.15). In addition, no ciprofloxacin-treated patients compared with 4 placebo-treated patients (2%) were admitted to the hospital for febrile UTI after the procedure. Ciprofloxacin reduced the expected net costs of treating infectious complications after biopsy by $23 per patient for an overall annual savings of $68,195 in the five study groups when compared with placebo.

CONCLUSIONS

Single-dose oral ciprofloxacin reduced bacteriuria after biopsy compared with placebo in patients undergoing transrectal prostatic biopsy and provided an economic advantage. In addition, this study establishes the actual rate of bacteriuria after transrectal needle biopsy of the prostate without antibiotic prophylaxis to be 8% with a clinical rate of UTI of 5% and a hospitalization rate of 2%.

Ciprofloxacin versus cefuroxime axetil in the treatment of adult patients with acute bacterial sinusitis

OBJECTIVE

This study compared the use and efficacy of ciprofloxacin to cefuroxime axetil for adult patients with acute bacterial sinusitis.

METHOD

We conducted a prospective, randomized, double-blind pilot study of oral ciprofloxacin (500 mg twice daily) versus cefuroxime axetil (250 mg twice daily) for 2 to 3 weeks in the treatment of adult patients with a clinical diagnosis of acute bacterial maxillary sinus infections or acute exacerbation of chronic bacterial sinusitis. Patients with microbiologically and radiologically confirmed sinusitis infection composed the efficacy population.

RESULTS

Of the 83 patients enrolled, 13 of 42 (31%) ciprofloxacin- and 19 of 41 (46%) cefuroxime axetil-treated patients had a respiratory pathogen isolated from a sinus aspiration. The most frequent pretherapy isolated included Haemophilus influenzae (11), streptococcus species (20), staphylococcus species (7), Proteus mirabilis (3), and Neisseria sicca (3). At the end of therapy, clinical resolution or improvement in efficacy-valid patients was achieved in 12 (100%) ciprofloxacin-treated patients and in 14 (74%) cefuroxime axetil recipients. The five (26%) cefuroxime axetil clinical failures were due to development of superinfection. Bacteriologic eradication occurred in 12 (100%) and 14 (100%) ciprofloxacin and cefuroxime axetil patients, respectively. Similar clinical and bacteriologic response rates were observed at the 2- to 4-week follow-up. Among 83 intent-to-treat patients, 19 (45%) ciprofloxacin and 14 (34%) cefuroxime axetil patients had drug-related adverse events. The most common adverse event in both treatment groups was gastrointestinal.

CONCLUSION

This pilot study suggests that ciprofloxacin is efficacious in the management of acute bacterial sinusitis.

Sequential ciprofloxacin therapy in pediatric cystic fibrosis: comparative study vs. ceftazidime/tobramycin in the treatment of acute pulmonary exacerbations. The Cystic Fibrosis Study Group

BACKGROUND

Cystic fibrosis patients have chronic bacterial infections of the respiratory tract, most commonly Pseudomonas aeruginosa. Although controversial, administration of antibiotic therapy during acute pulmonary exacerbations is standard practice. Fluoroquinolones are currently not indicated for use in young children because of the observation of arthropathy and damage to growing cartilage in beagle puppies. Because of its activity against P. aeruginosa and excellent oral bioavailability, ciprofloxacin offers a unique therapeutic alternative for this patient population.

OBJECTIVE

This prospective, randomized, double blind study compared the efficacy and safety of sequential intravenous/oral ciprofloxacin vs. ceftazidime/tobramycin in hospitalized pediatric cystic fibrosis patients with an acute pulmonary exacerbation associated with P. aeruginosa infection.

METHODS

One hundred thirty patients (ages 5 to 17 years) were randomized to receive either i.v. ciprofloxacin 10 mg/kg every 8 h for 7 days followed by oral ciprofloxacin 20 mg/kg every 12 h for a minimum of 3 days or i.v. ceftazidime 50 mg/kg every 8 h plus i.v. tobramycin 3 mg/kg every 8 h for a minimum of 10 days. Clinical, bacteriologic and safety responses were assessed throughout the study.

RESULTS

All 84 patients (median age, 11 years; range, 5 to 17 years) valid for efficacy in both treatment groups demonstrated clinical improvement. Five patients experienced clinical relapses (3 ciprofloxacin, 2 ceftazidime/tobramycin) by the 2- to 4-week follow-up. Intent-to-treat analysis demonstrated similar clinical findings between the two treatment groups at both the end of therapy and follow-up. Clinical improvement correlated with improvement in pulmonary function studies and the acute clinical scoring system but not with bacteriologic eradication of Pseudomonas. DNA profiles demonstrated that irrespective of colony morphology, usually one clonal strain was associated with each patient's pulmonary exacerbation. Treatment-associated musculoskeletal events occurred with equal frequency (22% vs. 21%) in both study drug groups (n = 129), and arthralgias were within the range of rates for cystic fibrosis arthropathy. None of these events required study drug discontinuation.

CONCLUSION

Sequential i.v./oral ciprofloxacin monotherapy offers a safe and efficacious alternative to standard parenteral therapy for acute pulmonary exacerbations in pediatric cystic fibrosis patients.

Pharmacokinetic disposition of sequential intravenous/oral ciprofloxacin in pediatric cystic fibrosis patients with acute pulmonary exacerbation

OBJECTIVE

Information about the pharmacokinetics of fluoroquinolone antibiotics in high risk children is scant. This study examined the disposition of sequentially administered intravenous and oral ciprofloxacin, as well as provided dosing recommendations, for the treatment of acute pulmonary exacerbations in pediatric cystic fibrosis patients.

METHODS

After enrollment in a Food and Drug Administration approved protocol, the pharmacokinetic profiles of ciprofloxacin (CIP) administered to 18 children with cystic fibrosis (ages 5 to 17 years) were studied at steady state after sequentially administered intravenous (10 mg/kg every 8 h) and oral (20 mg/kg every 12 h) doses. All children enrolled met published criteria for exacerbation of Pseudomonas aeruginosa lung infection and received CIP intravenously (given as a 1-h infusion) followed by oral administration, each for a minimum of 3 days. All patients were at a mild to moderate stage in their disease with National Institutes of Health scores between 37 and 83. Blood samples were drawn at 0, 0.5, 1.0, 1.5, 2.0, 4.0, 6.0, 8.0 (after both i.v. and oral dosing) and 12 h (oral only) after CIP administration. CIP serum concentrations were determined by high performance liquid chromatography.

RESULTS

After oral CIP mean +/- SD peak serum concentrations and peak times were 3.7 +/- 1.4 mg/l and 2.5 +/- 1.8 h, respectively, compared with 5.0 +/- 1.5 mg/l and 1.0 +/- 0.3 h after completion of the i.v. infusion. Maximum concentrations, when normalized for dose, were 0.52 +/- 0.12 and 0.19 +/- 0.07 mg/l/kg after i.v. and oral dosing, respectively. The mean bioavailability of oral CIP for all patients was 76%; younger patients appeared to absorb oral CIP less than older subjects, 68% vs. 95%, respectively. For all patients elimination half-lives were 2.6 +/- 0.6 and 3.4 +/- 0.7 h after i.v. and oral administration, respectively, and did not differ by age. Total clearance after i.v. administration was 19.5 +/- 10.9 liters/h. No significant CIP-related adverse effects were noted.

CONCLUSIONS

CIP doses of 30 mg/kg/day i.v. and 40 mg/kg/day orally must be administered to children with cystic fibrosis to achieve optimal therapeutic concentrations.

Results of a randomized trial comparing sequential intravenous/oral treatment with ciprofloxacin plus metronidazole to imipenem/cilastatin for intra-abdominal infections. The Intra-Abdominal Infection Study Group

OBJECTIVE

In a randomized, double-blind, multicenter trial, ciprofloxacin/metronidazole was compared with imipenem/cilastatin for treatment of complicated intra-abdominal infections. A secondary objective was to demonstrate the ability to switch responding patients from intravenous (IV) to oral (PO) therapy.

SUMMARY BACKGROUND DATA

Intra-abdominal infections result in substantial morbidity, mortality, and cost. Antimicrobial therapy often includes a 7- to 10-day intravenous course. The use of oral antimicrobials is a recent advance due to the availability of agents with good tissue pharmacokinetics and potent aerobic gram-negative activity.

METHODS

Patients were randomized to either ciprofloxacin plus metronidazole intravenously (CIP/MTZ IV) or imipenem intravenously (IMI IV) throughout their treatment course, or ciprofloxacin plus metronidazole intravenously and treatment with oral ciprofloxacin plus metronidazole when oral feeding was resumed (CIP/MTZ IV/PO).

RESULTS

Among 671 patients who constituted the intent-to-treat population, overall success rates were as follows: 82% for the group treated with CIP/MTZ IV; 84% for the CIP/MTZ IV/PO group; and 82% for the IMI IV group. For 330 valid patients, treatment success occurred in 84% of patients treated with CIP/MTZ IV, 86% of those treated with CIP/MTZ IV/PO, and 81% of the patients treated with IMI IV. Analysis of microbiology in the 30 patients undergoing intervention after treatment failure suggested that persistence of gram-negative organisms was more common in the IMI IV-treated patients who subsequently failed. Of 46 CIP/MTZ IV/PO patients (active oral arm), treatment success occurred in 96%, compared with 89% for those treated with CIP/MTZ IV and 89% for those receiving IMI IV. Patients who received intravenous/oral therapy were treated, overall, for an average of 8.6 +/- 3.6 days, with an average of 4.0 +/- 3.0 days of oral treatment.

CONCLUSIONS

These results demonstrate statistical equivalence between CIP/MTZ IV and IMI IV in both the intent-to-treat and valid populations. Conversion to oral therapy with CIP/MTZ appears as effective as continued intravenous therapy in patients able to tolerate oral feedings.

Single-dose ciprofloxacin for the treatment of uncomplicated gonorrhea: a worldwide summary

BACKGROUND AND OBJECTIVES

Antibiotic therapy for Neisseria gonorrhoeae infections has evolved owing to the development of resistance to penicillin and tetracycline therapy. A variety of antimicrobials, including the fluoroquinolones, have been proposed as useful alternatives.

GOAL OF THE STUDY

To evaluate the efficacy and safety of oral ciprofloxacin as single-dose treatment for urogenital and extragenital gonococcal infections.

STUDY DESIGN

1180 patients with uncomplicated gonococcal infection received single-dose ciprofloxacin regimens ranging from 100 mg to 2000 mg to demonstrate microbiologic efficacy and to determine the minimum effective dose. Eight of 18 studies were randomized, controlled trials with ampicillin/probenecid, amoxicillin/probenecid, ceftriaxone, or spectinomycin as control drugs.

RESULTS

Although a ciprofloxacin dose-response was not detected, 250 mg was used in most of the studies. Among 815 patients with 910 infected sites receiving 250 mg of ciprofloxacin, bacteriologic eradication was achieved in 563 (100%) male urethral, 199 (100%) female cervical, 101 (99%) male and female rectal, and 47 (96%) male and female pharyngeal sites.

CONCLUSION

Although the World Health Organization and the Centers for Disease Control and Prevention have identified 500 mg of ciprofloxacin as a single-dose treatment regimen for uncomplicated gonorrhea, the clinical data from the multinational studies indicate that a 250-mg single-dose of ciprofloxacin is equally effective in the management of uncomplicated gonorrhea, including extragenital sites of infection.

The selection of appropriate dosages for intravenous ciprofloxacin

A variety of toxicological, clinical and pharmacokinetic parameters were utilized in an evolving process to determine the optimum dosage for intravenous ciprofloxacin. Despite the clinical efficacy of 200-300 mg administered every 12 h, there have been concerns that this might be inadequate for certain pathogens, including Pseudomonas aeruginosa, Staphylococcus aureus and streptococci. Pharmacokinetic studies have established the bioequivalence of the iv and oral formulations of ciprofloxacin. With respect to the AUC, 400 mg of iv ciprofloxacin was equivalent to 500 mg po and the Cmax of 400 mg administered iv over 1 h approximated that following a 750 mg tablet. Final FDA approval of iv ciprofloxacin was ultimately based on the demonstration of the bioequivalence of the iv and oral formulations, the latter having proven clinical efficacy. For severe systemic infections, a daily dosage of 1200 mg (400 mg tds) of iv ciprofloxacin would be equivalent to 1500 mg (750 mg bd) taken by mouth.

Pharmacokinetic profiles of ciprofloxacin after single intravenous and oral doses

Ciprofloxacin was administered to 12 healthy male volunteers at doses of 300 and 400 mg intravenously (i.v.) and 500 and 750 mg orally in a randomized, double-blind, single-dose, four-period crossover study. On each treatment day, each subject received both oral and i.v. formulations, one of which was a placebo. Blood and urine samples were obtained through 24 h postdose. By each dosing route, the pharmacokinetic profiles were dose proportional. The 400-mg i.v. dose was equivalent to the 500-mg oral dose with respect to the area under the concentration-time curve and was equivalent to the 750-mg oral dose with respect to the maximum concentration of ciprofloxacin in serum. The oral bioavailability was 78.0%. The steady-state volume of distribution averaged 178 liters, and the terminal half-life in serum after i.v. dosing was approximately 4.3 h. Renal clearance accounted for approximately 60% of total body clearance. No significant adverse events were associated with either route of administration.

Comparative in vitro activities of a new quinolone, WIN 57273, and piperacillin plus tazobactam against anaerobic bacteria

The in vitro activities of a new quinolone, WIN 57273, and the combination of piperacillin and tazobactam, a beta-lactamase inhibitor, were compared with those of cefoxitin, ceftizoxime, chloramphenicol, clindamycin, imipenem, metronidazole, and piperacillin for 123 clinical anaerobic isolates. Ceftizoxime and cefoxitin had equivalent activities, while metronidazole was active against gram-negative isolates. In the Bacteroides fragilis group, species other than B. fragilis were the most resistant. The combination of piperacillin with tazobactam in a ratio of 8 to 1 was more effective than piperacillin against B. fragilis group organisms when the MIC of piperacillin was greater than or equal to 64 micrograms/ml. Overall, WIN 57273 (i) and imipenem (ii) were the most active agents, with MICs for 50 and 90% of strains of (i) 0.25 and 0.5 and (ii) 0.125 and 2 microgram/ml, respectively.

Comparative serum bactericidal activity of ceftizoxime/metronidazole, ceftizoxime, clindamycin, and imipenem against obligate anaerobic bacteria

We compared the bactericidal activity of serum obtained from healthy volunteers after single intravenous infusions of the combination of ceftizoxime (1 g) plus metronidazole (1 g) and after infusions of ceftizoxime (2 g), clindamycin (900 mg), and imipenem (1 g) against six obligate anaerobes. All agents were bactericidal but only the combination regimen resulted in bactericidal titres greater than 1:2 at 12 h for all the Bacteroides fragilis group organisms. High titres against Fusobacterium necrophorum and anaerobic Gram-positive cocci were attained with ceftizoxime/metronidazole, ceftizoxime, and imipenem 12 h after the dose. Imipenem and the combination of ceftizoxime/metronidazole had the greatest area under the bactericidal curve (AUBC) against the Bacteroides species. Clindamycin had a significantly smaller AUBC than other regimens for all strains tested except B. thetaiotaomicron. Clinical trials are needed to assess the efficacy and cost-benefit ratio of a 12 h dosing regimen of ceftizoxime in combination with metronidazole for treating mixed aerobic/anaerobic infections.

Cat-scratch disease in a patient with AIDS

A case of cat-scratch disease (CSD) in a patient with acquired immunodeficiency syndrome (AIDS) is reported. The lymph node pathologic characteristics were altered from those usually seen with CSD, showing clusters of vacuolated macrophages admixed with pycnotic nuclear debris instead of the usual suppurative granulomas. Evidence for the diagnosis was provided by Warthin-Starry stain and electron microscopic demonstration of the presumed CSD bacillus. Empiric treatment with antibiotics brought about clinical improvement. This case demonstrates the altered lymph node pathologic characteristics with CSD that may occur in a patient with AIDS.

Rapid detection of cytomegalovirus by fluorescent monoclonal antibody staining and in situ DNA hybridization in a dram vial cell culture system

By using dram vial cell culture methods, three commercially available tests for cytomegalovirus (CMV) detection were compared: direct fluorescent monoclonal antibody staining for CMV-specific early and late antigens (direct FA), indirect fluorescent monoclonal antibody staining for a CMV-specific early antigen (indirect FA), and in situ DNA hybridization with a biotinylated CMV-specific DNA probe kit (DNA probe). Of those tests, only the indirect FA provided consistent, reliable virus detection within the initial 24 h postinfection for serial 10-fold dilutions of CMV AD169 (laboratory strain) and for three selected urine samples. However, when used prospectively, the indirect FA failed to detect virus within the initial 10 days postinfection in 15 of 78 consecutive specimens that were eventually positive by cell culture. Although the indirect FA was more sensitive than the direct FA or DNA probe, its utility appeared limited to specimens with high CMV concentrations. On the basis of these data, we recommend that indirect FA be reserved as an adjunct to standard cell culture for selected samples in diagnostic hospital laboratories.

Cephalosporin therapy in intraabdominal infections. A multicenter randomized, comparative study of cefotetan, moxalactam, and cefoxitin

Three broad-spectrum cephalosporins (cefotetan, moxalactam, and cefoxitin) proved effective in this randomized, prospective trial for treatment of 303 surgical patients with moderately severe regional peritonitis.

A multicenter comparative study of cefotetan once daily and cefoxitin thrice daily for the treatment of infections of the skin and superficial soft tissue

To compare the effectiveness of cefotetan administered at 2 g once a day with cefoxitin at 1 or 2 g three times a day in the treatment of hospitalized patients with skin and superficial soft tissue infections, 194 patients from eight centers were enrolled in an open, randomized trial. Most of the 104 evaluable patients in the cefotetan group and 50 in the cefoxitin group were young men with community-acquired, moderate or severe cellulitis, or abscesses of the upper and lower extremities caused by Staphylococcus aureus, Streptococcus species, Escherichia coli, Proteus mirabilis, Bacteroides fragilis and other species of bacteroides, peptococcus species, and peptostreptococcus species. The mean duration of treatment was 7.5 days for cefotetan and 7.1 days for cefoxitin. A successful clinical response was achieved in 97 percent of the cefotetan patients and in 94 percent of the cefoxitin patients. Of the 88 and 39 bacteriologically evaluable patients in the cefotetan and cefoxitin groups, respectively, a satisfactory bacteriologic response occurred in 96 percent and 87 percent of the patients. No clinically significant changes in clinical laboratory determinations were noted. The incidence of adverse reactions in the cefotetan group (17 percent) was significantly different from that for the cefoxitin group (6 percent) (p less than 0.05); however, the incidence of treatment-related reactions was not significant and the events were mild. Discontinuation of therapy was necessary only in two patients in whom allergic-type reactions developed. A once-daily regimen of cefotetan was as effective as thrice-daily cefoxitin in this study in the treatment of primarily polymicrobial, moderate, or severe infections of the skin and superficial soft tissue.

Comparative study of cefotetan and cefoxitin in the treatment of intra-abdominal infections

One hundred eighty-eight patients were enrolled in a multicenter, randomized clinical trial to compare the safety and effectiveness of 1 to 2 gm cefotetan every 12 hours with those of 1 to 2 gm cefoxitin every 6 hours in patients with intra-abdominal infections. Most of the infections were community acquired, were associated with gastrointestinal tract perforation, and were caused by both anaerobic and aerobic bacteria. The median duration of therapy was 6 days for each group. The clinical response rate for the 95 evaluable patients in the cefotetan group was 98%, and that for the 43 evaluable patients in the cefoxitin group was 95%. Bacteriologically, 97% of the 58 evaluable patients in the cefotetan group and 89% of the 27 evaluable patients in the cefoxitin group had a satisfactory or presumed satisfactory response; two patients in the cefotetan group and three in the cefoxitin group were considered bacteriologic failures. Cefotetan was as effective as cefoxitin in eradicating Bacteroides fragilis and other species of Bacteroides, Clostridium sp., and gram-negative bacilli. The incidence of treatment-related adverse reactions for cefotetan (27%) was not statistically different from that for cefoxitin (17%). No clinically significant differences were detected between the treatment groups in changes in the results of clinical laboratory tests performed before and after treatment; a decrease in hematocrit among the cefotetan group was statistically greater (p = 0.04) than that for the cefoxitin group, and a decrease in serum creatinine level for the cefoxitin group was greater than that for the cefotetan group (p = 0.02). Cefotetan may represent an effective, safe, and cost-saving alternative to cefoxitin for the prompt treatment of community-acquired intra-abdominal infections.

Effect of peritoneal dialysis fluid and pH on bactericidal activity of ciprofloxacin

Ciprofloxacin is active in vitro against most bacteria that cause peritonitis associated with peritoneal dialysis. We compared the effects of pH (5.5 and 7.4) and medium (dialysis fluid) on the bactericidal activity of ciprofloxacin, tobramycin, vancomycin plus rifampin, and rifampin against Pseudomonas aeruginosa, Escherichia coli, and three strains of staphylococci. The bactericidal activity of ciprofloxacin was not significantly affected by pH or medium, in contrast to the activity of tobramycin, which was decreased by low pH.

Clindamycin phosphate kinetics in subjects undergoing CAPD

The kinetics of intraperitoneally administered clindamycin phosphate were studied in 9 volunteer subjects undergoing CAPD. Volunteers were assigned to 2 groups with the first group receiving clindamycin phosphate 300 mg/l in exchanges 1 through 5, and the second group receiving clindamycin phosphate 300 mg/l in exchange 1, and then 30 mg/l in exchanges 2 through 5. Clindamycin serum and dialysate effluent levels were determined by bioassay. When admixed with dialysate fluid and instilled into the peritoneal cavity, clindamycin phosphate is rapidly activated. Serum concentrations of clindamycin were rapidly achieved in both groups during the first exchange. Subjects in groups I and II had peak serum levels of active drug within 3 (3.94 ug/ml) and 5 (7.35 ug/ml) h, respectively. These results support the practice of not only administering intraperitoneal clindamycin phosphate to treat CAPD-related peritonitis, but using this route of administration to treat systemic infections due to susceptible bacteria in patients without intravenous access.

Lung abscess due to Corynebacterium equi. Report of the first case in a patient with acquired immune deficiency syndrome

A lung abscess and persistent bacteremia due to Corynebacterium equi are described in a bisexual man with the acquired immune deficiency syndrome (AIDS). Eleven of the 12 previously reported cases have occurred in immunocompromised humans. The occurrence of this infection in a patient with AIDS has not been previously described. Development of resistance to beta-lactam antibiotics was noted following initial therapy. Because this organism resembles nonpathogenic organisms, it may easily be overlooked despite its ability to cause serious infection and persist even with aggressive antimicrobial and surgical therapy.

Pharmacokinetics of ceftriaxone in subjects with renal insufficiency

The pharmacokinetics of ceftriaxone was studied in 14 men and women volunteers with renal insufficiency. Subjects were grouped by renal function: those with end-stage renal disease (CLcr less than 15 mL/min/1.73 sq m) but not receiving dialysis, those with severe renal insufficiency (CLcr 16-30 mL/min/1.73 sq m), and those with moderate renal insufficiency (CLcr 31-60 mL/min/1.73 sq m). Ceftriaxone 1 g as the sodium salt was administered by i.v. infusion over 30 minutes, and blood and urine samples were collected before and up to 48 hours after drug administration. The pharmacokinetic data were described using a nonlinear least-squares computer program. For volunteers with a creatinine clearance of less than 15 mL/min/1.73 sq m, the mean half-life was 15.6 hours. For subjects with a creatinine clearance of 31-60 mL/min/1.73 sq m, the mean half-life was 11.9 hours. Plasma ceftriaxone concentrations measured at the conclusion of the infusion (mean peak concentration 122 +/- 53.1 micrograms/mL) or 24 hours after the infusion (mean concentration 20.2 +/- 6.14 micrograms/mL) were similar in each study group. A dose of ceftriaxone 1 g every 24 hours in patients with renal insufficiency is probably adequate for inhibiting most susceptible gram-positive and gram-negative microorganisms.

The use of an antibiotic order form for antibiotic utilization review: influence on physicians' prescribing patterns

An antibiotic order form was implemented for all inpatient antibiotic orders at an 800-bed hospital in April 1981 to provide an ongoing, concurrent audit of antibiotic use. The prescribing physician provided the clinical indication for the antibiotic order, and individual patient treatment courses were identified. During the 25-month study period, cephalosporins, penicillin plus ampicillin, and aminoglycosides accounted for 44%, 22%, and 17% of all treatment courses, respectively. Sixty-nine percent of first-generation cephalosporin treatment courses were for prophylaxis, whereas the remaining antibiotics were used for either empirical therapy or documented infection in 56%-79% of cases. After the introduction of the antibiotic order form, there was a significant decline in both the number of antibiotic treatment courses (P = .025) and the percentage of patients receiving any antibiotic (P = .007). We conclude that a specialized antibiotic order form is an effective method for antibiotic utilization review and can have a significant impact on a physician's prescribing patterns.

Liquid chromatographic assay of ceftizoxime in sera of normal and uremic patients

The application of high-pressure liquid chromatography assays for cephalosporin serum concentrations is difficult in uremic patients because of interference from nondialyzable substances. We developed a high-pressure liquid chromatography method for determining the serum concentration of ceftizoxime in normal and uremic patients. The method involves protein precipitation with acetonitrile, followed by removal of the acetonitrile with dichloromethane. Separation was accomplished with a reverse-phase (C-18) column and a mobile phase of 13% acetonitrile and 2.8% acetic acid. UV detection at 310 nm was used to monitor the peaks. This assay produced a linear relationship between peak height ratio and ceftizoxime concentration from 1.5 to 100 micrograms/ml. Samples from 30 patients were assayed by this method and by a bioassay, with a good correlation of results (r = 0.9832). The method was applicable equally to normal and uremic serum samples.

Multidrug-resistant Serratia marcescens bacteriuria related to urologic instrumentation

An outbreak of urinary tract infections caused by multidrug-resistant Serratia marcescens lasted for 12 months and was found to be related to urologic instrumentation. Thirty-four patients had primary infections; four had cross-infections. Only six patients had indwelling bladder catheters. The median interval between instrumentation and initial isolation of Serratia was six days. Seventy-three percent of patients were symptomatic, two were bacteremic. No common instruments, personnel, or wards were identified, and environmental cultures failed to reveal the epidemic strain of Serratia. The outbreak ended when the instrument disinfectant was changed. Serotyping was identical in nine of ten isolates. Intraspecies conjugation demonstrated resistance transfer of gentamicin, tobramycin, carbenicillin, chloramphenicol, and co-trimoxazole. The enzyme 6'-N-acetyl transferase was responsible for gentamicin-inactivation in patient isolates and a transconjugate. Although no significant spread of this multidrug-resistance plasmid to other Enterobacteriaceae occurred in the hospital, two instances of apparent in vivo transfer to other bladder organisms occurred.