Impact of different carbapenems and regimens of administration on resistance emergence for three isogenic Pseudomonas aeruginosa strains with differing mechanisms of resistance.

We compared drugs (imipenem and doripenem), doses (500 mg and 1 g), and infusion times (0.5 and 1.0 [imipenem], 1.0 and 4.0 h [doripenem]) in our hollow-fiber model, examining cell kill and resistance suppression for three isogenic strains of Pseudomonas aeruginosa PAO1. The experiments ran for 10 days. Serial samples were taken for total organism and resistant subpopulation counts. Drug concentrations were determined by high-pressure liquid chromatography-tandem mass spectrometry (LC/MS/MS). Free time above the MIC (time > MIC) was calculated using ADAPT II. Time to resistance emergence was examined with Cox modeling. Cell kill and resistance emergence differences were explained, in the main, by differences in potency (MIC) between doripenem and imipenem. Prolonged infusion increased free drug time > MIC and improved cell kill. For resistance suppression, the 1-g, 4-h infusion was able to completely suppress resistance for the full period of observation for the wild-type isolate. For the mutants, control was ultimately lost, but in all cases, this was the best regimen. Doripenem gave longer free time > MIC than imipenem and, therefore, better cell kill and resistance suppression. For the wild-type organism, the 1-g, 4-h infusion regimen is preferred. For organisms with resistance mutations, larger doses or addition of a second drug should be studied.

Identifying exposure targets for treatment of staphylococcal pneumonia with ceftobiprole.

Ceftobiprole is a cephalosporin with potent activity against methicillin (meticillin)-resistant Staphylococcus aureus (MRSA). In order to treat patients with severe staphylococcal pneumonia, it is important to understand the drug exposure required to mediate the killing of multiple log(10) cells in a preclinical-infection model. We measured drug exposure in terms of the percentage of penetration of the drug into epithelial lining fluid (ELF) and in terms of the time for which the drug concentration was above the MIC (time>MIC) in plasma and ELF. In a murine model of staphylococcal pneumonia, we demonstrated that ceftobiprole penetrated into ELF from the plasma at a median level of nearly 69% (25th to 75th percentile range, 25 to 187%), as indexed to the ratio of values for the area under the concentration-time curve in ELF and plasma. The total-drug times>MIC in ELF that were required to kill 1 log(10) and 2 log(10) CFU/g of lung tissue were 15% and 25% of the dosing interval. We also examined the penetration of ELF by ceftobiprole in volunteers, demonstrating mean and median penetration percentages of 25.5% and 15.3%, respectively (25th to 75th percentile range, 8 to 30%). Attainment rates were calculated for kill targets of 1 log(10) and 2 log(10) CFU/g, taken from the murine model, but using the volunteer ceftobiprole ELF penetration data. The standard dose for ceftobiprole is 0.5 g every 8 h as a 2-h infusion. The attainment rates remained above 90% for 1-log(10) and 2-log(10) CFU/g kill targets at MICs of 1 and 0.5 mg/liter, respectively. Taking the expectation over the distribution of ceftobiprole MICs for 4,958 MRSA isolates showed an overall target attainment of 85.6% for a 1-log(10) CFU/g kill and 79.7% for a 2-log(10) CFU/g kill. It is important to derive exposure targets in preclinical-infection models of the infection site so that these targets can be explored in clinical trials in order to optimize the probability of a good clinical outcome.

Application of a mathematical model to prevent in vivo amplification of antibiotic-resistant bacterial populations during therapy.

The worldwide increase in the prevalence of multi-antibiotic-resistant bacteria has threatened the physician's ability to provide appropriate therapy for infections. The relationship between antimicrobial drug concentration and infecting pathogen population reduction is of primary interest. Using data derived from mice infected with the bacterium Pseudomonas aeruginosa and treated with a fluoroquinolone antibiotic, a mathematical model was developed that described relationships between antimicrobial drug exposures and changes in drug-susceptible and -resistant bacterial subpopulations at an infection site. Dosing regimens and consequent drug exposures that amplify or suppress the emergence of resistant bacterial subpopulations were identified and prospectively validated. Resistant clones selected in vivo by suboptimal regimens were characterized. No mutations were identified in the quinolone resistance-determining regions of gyrA/B or parC/E. However, all resistant clones demonstrated efflux pump overexpression. At base line, MexAB-OprM, MexCD-OprJ, and MexEF-OprN were represented in the drug-resistant population. After 28 hours of therapy, MexCD-OprJ became the predominant pump expressed in the resistant clones. The likelihood of achieving resistance-suppression exposure in humans with a clinically prescribed antibiotic dose was determined. The methods developed in this study provide insight regarding how mathematical models can be used to identify rational dosing regimens that suppress the amplification of the resistant mutant population.

Serial sinus aspirate samples during high-dose, short-course levofloxacin treatment of acute maxillary sinusitis.

This study assessed daily aspirate samples from an indwelling sinus catheter during high-dose, short-course levofloxacin (750 mg daily x 5 days) treatment of acute maxillary sinusitis. Pathogens were isolated from 4 of 18 recruited patients. Bacteriologic eradication occurred within 24 h for 3 patients and 72 h for the 4th.

Identification and pretherapy susceptibility of pathogens in patients with complicated urinary tract infection or acute pyelonephritis enrolled in a clinical study in the United States from November 2004 through April 2006.

OBJECTIVE: The purpose of this study was to assess the pretherapy microbiology and fluoroquinolone susceptibility of pathogens from 650 patients with complicated urinary tract infection (cUTI) or acute pyelonephritis (AP) as part of a multicenter, randomized, controlled clinical trial. METHODS: In this post hoc analysis of a multicenter, randomized, double-blind study, adults with a clinical diagnosis of cUTI or AP were recruited from 130 community-based and institution-based study centers in the United States from November 2004 through April 2006. Urine and blood culture specimens were identified and tested for susceptibility according to Clinical and Laboratory Standards Institute methods. Presence of a pathogen in the urine culture was confirmed by a colony count of =105 colony-forming units per milliliter. Susceptibility to nonstudy drugs (trimethoprim/sulfamethoxazole [TMP/SMX] and ampicillin) and to study drugs (levofloxacin and ciprofloxacin) was categorized as susceptible, intermediate, or resistant. RESULTS: Six hundred fifty patients (417 women, 233 men; age range, 18-94 years) with a diagnosis of cUTI or AP were recruited. A total of 68.2% patients (224 men, 219 women) were diagnosed with cUTI, and 31.8% (198 women, 9 men), with AP. Most (646/650 [99.4%]) infections were community acquired. The most common pathogen was Escherichia coli (65.6%), although 12.2% of patients had gram-positive pathogens. Testing for susceptibility to ampicillin and TMP/SMX found that 50.1% and 22.1% of gramnegative pathogens were fully resistant to ampicillin and TMP/SMX, respectively. However, 91.9% of isolates were susceptible to levofloxacin and ciprofloxacin, with 6.5% of isolates resistant or intermediately resistant to levofloxacin, and 9.7% of isolates resistant or intermediately resistant to ciprofloxacin at study entry (P < 0.001 [Stuart-Maxwell test]). All isolates resistant to levofloxacin were also resistant to ciprofloxacin, whereas 6 isolates that were fully susceptible to levofloxacin were fully resistant to ciprofloxacin. CONCLUSION: In this study, the level of fluoroquinolone susceptibility of urinary pathogens was high (90.6% in cUTI; 98.1% in AP).

Levofloxacin 750 mg QD for five days versus amoxicillin/clavulanate 875 mg/125 mg BID for ten days for treatment of acute bacterial exacerbation of chronic bronchitis: a post hoc analysis of data from severely ill patients.

This post hoc analysis of data from a previous randomized, blinded, multicenter, parallel, noninferiority study assessed the bacterial etiology, symptom resolution, and tolerability of severe acute bacterial exacerbation of chronic bronchitis (ABECB) patients treated with either levofloxacin 750 mg QD for 5 days or amoxicillin/clavulanate 875 mg/125 mg BID for 10 days. Severe ABECB was defined as ABECB and forced expiratory volume in 1 second (FEV(1)) <50% of the predicted value, or (FEV(1)) of 50% to 65% of the predicted value plus comorbidities, or > or =4 exacerbations per year. A total of 369 patients were included in the intent-to-treat (ITT) population (187 treated with levofloxacin and 182 treated with amoxicillin/clavulanate), and 175 patients were microbiologically assessable (MA) (86 treated with levofloxacin and 89 treated with amoxicillin/clavulanate). In the ITT population, the mean age was 58.7 years, 49.1 % were male, and 48.2% were current smokers. At the on-treatment visit, a significantly higher proportion of MA patients in the levofloxacin group resolved purulent sputum production (57.5% vs 35.6%; P < 0.006), sputum production (65.4% vs 45.3%; P < 0.013), and cough (60.0% vs 44.0%; P < 0.045), compared with the amoxicillin/clavulanate group. However, no significant between-group differences were observed at posttreatment. A total of 341 pathogens were isolated, of which 143 (41.9%) were traditional ABECB flora, 181 (53.1%) were other gram-negative organisms, and 17 (5.0%) were gram-positive organisms. Overall susceptibility of the pathogens was 97.1% for levofloxacin and 90.6% for amoxicillin/clavulanate (P < 0.001). The prevalence of treatment-emergent adverse events was 42.1 % in patients who received levofloxacin and 48.6 % in those who received amoxicillin/clavulanate (95% CI,-4.0 to 17.0).

Levofloxacin 750-mg for 5 days for the treatment of hospitalized Fine Risk Class III/IV community-acquired pneumonia patients.

BACKGROUND: The efficacy and safety of 750-mg, 5-day levofloxacin was recently shown to be comparable to 500-mg, 10-day levofloxacin in a randomized, double-blind, multicentre clinical trial for mild-to-severe community-acquired pneumonia (CAP). This subgroup analysis attempted to compare the safety and efficacy of a short-course levofloxacin regimen with traditional levofloxacin dosing for PSI Class III/IV patients. METHODS: This retrospective, subgroup analysis focused on Pneumonia Severity Index Class III and IV patients enrolled in the study. Measurements included clinical and microbiological success rates, adverse events, and symptom resolution by day 3 of therapy. RESULTS: Of the 528 patients in the ITT population, 219 (41.5%) were categorized as PSI Class III/IV and included in this analysis. Among the clinically evaluable patients, 90.8% (69/76) of patients treated with the 750-mg regimen achieved clinical success, compared with 85.5% (71/83) treated with 500-mg levofloxacin (95% CI,-15.9 to 5.4). Eradication rates in the microbiologically evaluable population were comparable for the 750- and 500-mg regimens (88.9% vs 87.5%, respectively; 95% CI,-18.3 to 15.6). Both regimens were well tolerated and had comparable safety profiles. A greater proportion of patients in the 750-mg treatment group experienced resolution of fever (48.4% vs 34.0%; P=.046) and purulent sputum (48.4% vs 27.5%; P=.007) by day 3 of therapy. CONCLUSIONS: The 750-mg, 5-day levofloxacin course achieved comparable clinical and microbiologic efficacy to the 500-mg, 10-day regimen. By day 3 of therapy, a greater proportion of patients in the 750-mg group had objective and subjective resolution of fever. Further research is needed to determine the economic significance of short-course levofloxacin therapy.

High-dose, short-course levofloxacin for community-acquired pneumonia: a new treatment paradigm.

Levofloxacin demonstrates concentration-dependent bactericidal activity most closely related to the pharmacodynamic parameters of the ratio of area under the concentration-time curve (AUC) to minimum inhibitory concentration (MIC) and the ratio of peak plasma concentration (C(max)) to MIC. Increasing the dose of levofloxacin to 750 mg exploits these parameters by increasing peak drug concentrations, allowing for a shorter course of treatment without diminishing therapeutic benefit. This was demonstrated in a multicenter, randomized, double-blind investigation that compared levofloxacin dosages of 750 mg per day for 5 days with 500 mg per day for 10 days for the treatment of mild to severe community-acquired pneumonia (CAP). In the clinically evaluable population, the clinical success rates were 92.4% (183 of 198 persons) for the 750-mg group and 91.1% (175 of 192 persons) for the 500-mg group (95% confidence interval, -7.0 to 4.4). Microbiologic eradication rates were 93.2% and 92.4% in the 750-mg and 500-mg groups, respectively. These data demonstrate that 750 mg of levofloxacin per day for 5 days is at least as effective as 500 mg per day for 10 days for treatment of mild-to-severe CAP.

Levofloxacin compared with imipenem/cilastatin followed by ciprofloxacin in adult patients with nosocomial pneumonia: a multicenter, prospective, randomized, open-label study.

BACKGROUND: Therapy of nosocomial pneumonia is usually empiric and includes > or = 1 broad-spectrum antimicrobial agent. When considering the use of fluoroquinolones in these difficult-to-treat infections--in which drug delivery to the site of infection may be impaired or organisms with higher minimum inhibitory concentrations may be present--an agent should be chosen whose pharmacodynamics ensure maximal drug exposure. Use of the 750-mg dose of levofloxacin should enhance therapeutic benefit in patients with nosocomial pneumonia. OBJECTIVE: The goal of this study was to compare the efficacy and safety of levofloxacin 750 mg and imipenem/cilastatin followed by ciprofloxacin in adult patients with nosocomial pneumonia. METHODS: This was a multicenter, prospective, randomized, open-label trial conducted in North America. Patients were randomly assigned to 1 of 2 treatment arms: levofloxacin 750 mg QD given i.v. and then orally for 7 to 15 days or imipenem/cilastatin 500 mg to 1 g i.v. every 6 to 8 hours, followed by oral ciprofloxacin 750 mg every 12 hours for 7 to 15 days. Adjunctive antibacterial therapy was mandatory in patients with documented or suspected Pseudomonas aeruginosa or methicillin-resistant Staphylococcus aureus infection. The primary predefined outcome measure was the clinical response (cure, improvement, failure, or unable to evaluate) in microbiologically evaluable patients 3 to 15 days after the end of therapy. RESULTS: The study enrolled 438 adult patients (315 men, 123 women; mean [SD] age, 55.7 [20.04] years). Two hundred twenty patients received levofloxacin, and 218 received the comparator regimen. Demographic and baseline clinical characteristics were similar in the intent-to-treat and clinically evaluable populations. In patients evaluable for microbiologic efficacy, clinical success (cure or improvement) was achieved in 58.1% (54/93) of patients who received levofloxacin, compared with 60.6% (57/94) of patients who received the comparator regimen (95% CI, -12.0 to 17.2). Similar clinical results were seen in patients evaluable for clinical efficacy and in the intent-to-treat population. In the 187 patients evaluable for microbiologic efficacy, eradication was achieved in 66.7% (62/93) of patients receiving levofloxacin and 60.6% (57/94) of patients receiving the comparator regimen (95% CI, -20.3 to 8.3). CONCLUSION: In this study, levofloxacin was at least as effective and was as well tolerated as imipenem/cilastatin followed by ciprofloxacin in adult patients with nosocomial pneumonia, as demonstrated by comparable clinical and microbiologic success rates.

A multicenter, open-label, randomized comparison of levofloxacin and azithromycin plus ceftriaxone in hospitalized adults with moderate to severe community-acquired pneumonia.

BACKGROUND: Changing etiologic patterns and the growing problem of antimicrobial resistance, particularly an increase in macrolide-resistant pneumococcal bacteremia, are causing physicians to adopt new approaches to the treatment of community-acquired pneumonia (CAP). OBJECTIVE: The relative efficacy and tolerability of levofloxacin monotherapy and azithromycin and ceftriaxone combination therapy were assessed in hospitalized adults with moderate to severe CAP. METHODS: This Phase IV, multicenter, open-label, randomized trial compared 2 treatment regimens: (1) levofloxacin 500 mg PO or IV q24h, and (2) azithromycin 500 mg IV q24h for > or = 2 days plus ceftriaxone 1 g IV q24h for 2 days, followed by an optional transition to azithromycin 500 mg PO q24h at the investigator's discretion. The total duration of therapy was to be a minimum of 10 days in both treatment groups. Ceftriaxone was included in the initial azithromycin regimen to ensure coverage against pneumococcal bacteremia. RESULTS: Of 236 patients in the intent-to-treat population, completion or withdrawal information was available for 110 patients in the levofloxacin group and 114 in the azithromycin group. Baseline demographic and disease characteristics were comparable between groups. At the end of treatment, the clinical success rate (cured + improved) in clinically evaluable patients was 94.1% in the levofloxacin group and 92.3% in the azithromycin group. The respective posttherapy microbiologic eradication rates were 89.5% and 92.3%. Levofloxacin was as well tolerated as azithromycin, with an incidence of drug-related adverse events (AEs) for all body systems of 5.3% and 9.3%, respectively. None of the drug-related AEs were considered serious [corrected]. CONCLUSIONS: In this study in hospitalized patients with moderate to severe CAP, levofloxacin monotherapy was at least as effective as a combination regimen of azithromycin and ceftriaxone in providing coverage against the current causative pathogens in CAP. In addition, levofloxacin was as well tolerated as the combination of azithromycin and ceftriaxone.

Efficacy of 750-mg, 5-day levofloxacin in the treatment of community-acquired pneumonia caused by atypical pathogens.

BACKGROUND: Current recommended durations for treatment of atypical community-acquired pneumonia (CAP) range from 10 to 21 days. However, antibiotics such as the fluoroquinolones may allow for effective, short-course regimens. OBJECTIVE: This study evaluated the efficacy of 750 mg levofloxacin for 5 days compared to a 500-mg, 10-day levofloxacin regimen for the treatment of atypical CAP. METHODS: A randomized, active-controlled, double-blind, multicenter study was conducted within the United States. Of the 528 patients enrolled in the study, 149 were diagnosed with CAP due to Legionella pneumophila, Chlamydia pneumoniae, or Mycoplasma pneumoniae. Patients' baseline symptoms were re-evaluated on Day 3 of therapy. Clinical efficacy and resolution of CAP symptoms were evaluated at the posttherapy visit (7-14 days after the last dose of active drug). RESULTS: This report represents a subgroup analysis of a previous clinical study. Among the 123 clinically evaluable patients diagnosed with atypical CAP (26 patients were unevaluable), the clinical success rates were 95.5% (63 of 66 patients) for the 750-mg group and 96.5% (55 of 57 patients) for the 500-mg group (95% CI for success rate of the 500-mg group minus that of the 750-mg group, -6.8 to 8.8). At the poststudy evaluation (31-38 days after treatment began), relapse occurred in

Safety and efficacy of levofloxacin 750 mg for 2 weeks or 3 weeks compared with levofloxacin 500 mg for 4 weeks in treating chronic bacterial prostatitis.

OBJECTIVE: To compare the safety and efficacy of levofloxacin 750 mg QD for 2 weeks or levofloxacin 750 mg QD for 3 weeks to levofloxacin 500 mg QD for 4 weeks in treating chronic bacterial prostatitis (CBP). RESEARCH DESIGN AND METHODS: This was a randomized, multicenter, double-blind, noninferiority study. The primary efficacy end point was investigator assessment of clinical success in the modified intent-to-treat (mITT) population at post-therapy. National Institutes of Health-Chronic Prostatitis Symptom Index (NIH-CPSI) scores were utilized to evaluate subject-reported responses post-therapy. RESULTS: A total of 241 subjects were enrolled. At post-therapy (test of cure [TOC]), clinical success rates for levofloxacin-treated subjects (750 mg QD for 3 weeks [64.9%, 48/74]) were noninferior to 500 mg QD for 4 weeks (69.3%, 52/75: 95% CI, -19.5%, 10.6%). Success rates with levofloxacin 750 mg QD for 2 weeks (63.0%, 46/73) were not noninferior to therapy with levofloxacin 500 mg QD for 4 weeks (95% CI, -21.5%, 8.9%) at TOC. At 3 and 6 months post-therapy, clinical success rates were clinically higher for the 500-mg, 4-week treatment group, and statistical analysis demonstrated both groups were not noninferior to standard therapy with levofloxacin 500 mg (95% CI, -32.5%, -0.6% for both 750-mg groups at 6 months). NIH-CPSI scores showed similar trends. Overall, adverse event (AE) rates were similar for the three treatment groups; however, discontinuation of therapy due to AEs was higher with the 750-mg dose (p = 0.02, and p = 0.13 for 750 mg, 2 weeks and 750 mg, 3 weeks versus 500 mg for 4 weeks, respectively). The main limitation of this study was that no bacterial cultures were required. CONCLUSIONS: Higher doses for shorter durations were determined to be no worse than standard therapy with levofloxacin 500 mg for a longer duration at the TOC visit. However, at the 6-month follow-up visit, the levofloxacin 750-mg dose administered for either 2 weeks or 3 weeks was inferior to the standard therapy, suggesting that a longer duration of treatment may help extend the relapse-free interval in patients with CBP. CLINICAL TRIAL REGISTRATION: clinicaltrials.gov, nct00402688.

A double-blind, randomized comparison of levofloxacin 750 mg once-daily for five days with ciprofloxacin 400/500 mg twice-daily for 10 days for the treatment of complicated urinary tract infections and acute pyelonephritis.

OBJECTIVES: A clinical study was conducted to compare the efficacy and safety of levofloxacin 750 mg once daily for 5 days to ciprofloxacin twice daily for 10 days for the treatment of complicated urinary tract infections (cUTI) or acute pyelonephritis (AP). METHODS: A multicenter, double-blind, randomized, noninferiority study enrolled subjects with AP or cUTI. Subjects received either levofloxacin 750 mg intravenously or orally once daily for 5 days or ciprofloxacin 400 mg intravenously and/or ciprofloxacin 500 mg orally twice daily for 10 days and were evaluated at end of therapy, posttherapy, and poststudy for microbiologic eradication and clinical outcome. RESULTS: A total of 1109 subjects were enrolled; 619 with confirmed diagnosis of AP or cUTI and a study entry uropathogen with a colony count 10(5) CFU/mL or greater and were included in the modified intent-to-treat population. Five hundred six subjects met all criteria for inclusion and were included in the microbiologically evaluable population. At end of therapy, eradication rates in the modified intent-to-treat population were 79.8% for levofloxacin and 77.5% for ciprofloxacin-treated subjects (95% CI, -8.8% to 4.1%). In the microbiologically evaluable population, eradication rates were 88.3% for levofloxacin and 86.7% for ciprofloxacin-treated subjects (95% CI, -7.4% to 4.2%). Outcomes were comparable for the 2 treatments at posttherapy and poststudy. CONCLUSIONS: This study demonstrates that both drug regimens are safe and effective and that a 5-day course of therapy with levofloxacin, administered at a dose of 750 mg once daily, is noninferior to a 10-day course of therapy with ciprofloxacin for the treatment of AP and cUTI.

Study entry microbiology in patients with acute bacterial exacerbation of chronic bronchitis in a clinical trial stratifying by disease severity.

OBJECTIVE: To examine study entry microbiology in patients stratified by disease severity in a clinical trial in acute bacterial exacerbation of chronic bronchitis (ABECB). METHODS: Patients were assigned to differing antibiotic therapies based on stratification by disease severity using parameters including forced expiratory volume in 1 second (FEV(1)) as a percentage of predicted value, number of exacerbations during the previous 12 months, and defined co-morbidities. All patients were required to have sputum Gram stain and culture at study entry. RESULTS: There was no statistically significant difference in overall microbiology between patients with less severe and more severe clinical presentations. Typical ABECB pathogens (Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis) were found in 46.2% (147/318) of patients with less severe presentations and 41.9% (143/341) of patients with more severe presentations. Gram-negative organisms and Staphylococcus aureus were also found in both groups. Pneumococcal susceptibilities to the three antibiotics utilized in the trial revealed marked resistance to azithromycin. Limitations of this analysis include that the clinical trial was designed to examine clinical outcomes rather than microbiology, and that we do not correlate study entry microbiology with clinical outcomes. CONCLUSIONS: Stratification of patients by disease severity did not reveal a statistically significant difference in overall microbiological profile. Gram-negative organisms and S. aureus were recovered even from patients with less severe clinical presentations. Pneumococcal resistance varied with the agent tested. These findings may have implications for the selection of appropriate antibiotic therapy.

A trial of levofloxacin 750 mg once daily for 5 days versus ciprofloxacin 400 mg and/or 500 mg twice daily for 10 days in the treatment of acute pyelonephritis.

OBJECTIVE: A double-blind, noninferiority trial was conducted to establish the safety and efficacy of a once-daily, 5-day course of levofloxacin 750 mg compared to a twice-daily, 10-day course of ciprofloxacin in complicated urinary tract infections (cUTI) and acute pyelonephritis (AP). This report focuses on subjects with AP. RESEARCH DESIGN AND METHODS: Adult male and female subjects with clinical signs and symptoms of AP and laboratory confirmation of their diagnosis were randomized to receive one dose of levofloxacin 750 mg once daily intravenously (i.v.) or orally and one dose of placebo for 5 days, followed by placebo; or ciprofloxacin 400 mg i.v. and/or 500 mg orally twice daily for 10 days. MAIN OUTCOME MEASURES: The primary, prospectively defined end point was microbiologic eradication at post-therapy (study days 15-22). Secondary outcomes included clinical response and safety and tolerability. RESULTS: In the modified intent-to-treat (mITT) population (levofloxacin 94, ciprofloxacin 98), 83% of levofloxacin-treated and 79.6% of ciprofloxacin-treated subjects achieved microbiological eradication (difference -3.4, 95% CI -14.4%, 7.6%). In the microbiologically evaluable (ME) population (levofloxacin 80, ciprofloxacin 76), 92.5% of levofloxacin-treated vs. 93.4% of ciprofloxacin-treated subjects (difference -0.9, 95% CI -7.1%, 8.9%) achieved microbiologic eradication. Clinical success was achieved in 86.2% vs. 80.6% (mITT) and in 92.5% vs. 89.5% (ME) of levofloxacin-treated and ciprofloxacin-treated subjects, respectively. Escherichia coli was the most commonly isolated uropathogen. Few (2.1%) of the pathogens were fluoroquinolone-resistant. Adverse events (AEs) were similar to those seen previously with both agents. Potential limitations are that this analysis is based on a subset of subjects from a larger study and, because of different durations of therapy, the results may be biased against levofloxacin. CONCLUSIONS: High-dose, short-course therapy with levofloxacin in subjects with AP is at least as effective as standard 10-day therapy with ciprofloxacin.

Probability of target attainment for ceftobiprole as derived from a population pharmacokinetic analysis of 150 subjects.

Ceftobiprole is a broad-spectrum cephalosporin with activity against methicillin-resistant Staphylococcus aureus (MRSA) that is undergoing phase III trials for the treatment of complicated skin and skin structure infections and nosocomial pneumonia. The objectives were to describe the pharmacodynamic profiles of ceftobiprole given at 500 mg intravenously (i.v.) every 8 h (q8h) (2-h infusion) and 500 mg i.v. every 12 h (q12h) (1-h infusion) to determine the overall probability of target attainment (PTA) by weighting for the expected distributions of renal function in the populations of interests, to determine the PTA against representative pathogens encountered in clinical trials, and to determine the optimal renal dose adjustment for ceftobiprole at 500 mg i.v. q8h (2-h infusion). Data for a total of 150 subjects in phase I/II trials were analyzed by using the population pharmacokinetic modeling program BigNPOD (nonparametric optimal design). Monte Carlo simulation was performed with the ADAPT II program to estimate the PTA at which the free drug concentrations exceed the MIC for 30 to 60% of the dosing interval (30 to 60% fT > MIC). For ceftobiprole at 500 mg i.v. q12h, the probabilities of achieving 30% and 50% fT > MIC exceeded 90% for MICs < or =2 mg/liter and < or =1 mg/liter, respectively, For ceftobiprole at 500 mg i.v. q8h, the probabilities of achieving 40 and 60% fT > MIC exceeded 90% for MICs < or =4 mg/liter and < or =2 mg/liter, respectively. For ceftobiprole at both 500 mg i.v. q12h and 500 mg i.v. q8h, the probability of achieving a nearly bactericidal effect (50% fT > MIC) exceeded 90% for methicillin-susceptible S. aureus and MRSA. For gram-negative pathogens, the PTA for achieving a nearly maximal bactericidal effect (60% fT > MIC) for ceftobiprole at 500 mg i.v. q8h exceeded 90% for non-AmpC-producing gram-negative organisms. Ceftobiprole at 500 mg i.v. q12h, for patients who had a creatinine clearance rate of < or =50 ml/min, was identified as the most appropriate treatment regimen for patients who require renal dose adjustment for mild to moderate renal impairment.

Comparison of the adverse event profiles of levofloxacin 500 mg and 750 mg in clinical trials for the treatment of respiratory infections.

OBJECTIVE: To compare safety data with levofloxacin 500 mg and 750 mg from clinical trials for the treatment of respiratory infections. METHODS: We compared adverse event data for levofloxacin 500 mg and 750 mg from clinical trials in acute bacterial sinusitis, acute bacterial exacerbation of chronic bronchitis, and community-acquired pneumonia. Adverse events occurring after the initiation of therapy were classified as treatment-emergent adverse events (TEAE); drug-related adverse events (DRAE) were TEAE assessed by the clinical investigator as definitely/very likely or probably related to levofloxacin therapy. RESULTS: Overall, the safety profile of the two doses was similar but not identical. TEAE occurred in 49.0% (1601/3268) of those treated with 500 mg and in 45.5% (519/1141) of those treated with 750 mg (p = 0.042); the corresponding rates of DRAE were 7.6% (248/3268) and 8.0% (91/1141) (p = 0.699). There was no statistically significant difference in terms of overall TEAE and DRAE rates within each of the three infectious conditions, but there were in specific events, all of which are expected with levofloxacin therapy. The limitations of this analysis include that it utilized a subset of available safety data, that it includes data only from clinical trials, and that we report primarily on events occurring in > or = 2% of patients. CONCLUSIONS: Given similar adverse event profiles and the advantages of higher dose therapy, including shorter courses of therapy and potential impact on preventing resistance, clinicians should consider utilizing the 750 mg dose of levofloxacin when choosing between dosage strengths for treatment of indicated infections.

Treatment of chronic bacterial prostatitis with levofloxacin and ciprofloxacin lowers serum prostate specific antigen.

PURPOSE: We compared baseline and post-therapy prostate specific antigen (PSA) in patients with chronic bacterial prostatitis who were treated with levofloxacin or ciprofloxacin. MATERIALS AND METHODS: Subset analysis was done using a randomized, multicenter, double-blind, active control trial of 500 mg levofloxacin daily for 28 days vs 500 mg ciprofloxacin twice daily in 28 days in men with chronic bacterial prostatitis. RESULTS: Of the 377 men in the intent to treat population, including 197 treated with levofloxacin and 180 treated with ciprofloxacin, 35 on levofloxacin and 37 on ciprofloxacin with baseline PSA greater than 4 ng/ml were included in this analysis. Excluded from analysis were 2 levofloxacin treated patients with extremely high PSA at baseline (62 and 103 ng/ml, respectively). Mean baseline PSA +/- SD in the patients analyzed was 8.33 +/- 4.46 ng/ml, which decreased to 5.36 +/- 3.82 ng/ml after therapy. There was no significant difference in the mean change in PSA between the levofloxacin and ciprofloxacin groups. Approximately 42% of patients with increased baseline PSA had a post-therapy PSA of 4 ng/ml or less. Of patients who were microbiologically evaluable and had normalized PSA after therapy levofloxacin eradicated the pathogen in 90.9% (10 of 11). However, of patients in whom post-therapy PSA remained increased the microbiological eradication rate was 69.2% (9 of 13). Similarly 93.3% of the ciprofloxacin group (14 of 15 patients) with normalized post-therapy PSA experienced microbiological eradication compared with 61.5% (8 of 13) with continued increased PSA after therapy. CONCLUSIONS: Approximately 20% of patients diagnosed with chronic bacterial prostatitis had increased PSA. A significant decrease in PSA was observed in these patients after treatment with levofloxacin or ciprofloxacin. An association was observed between bacterial persistence and the likelihood that PSA would return to normal.

Levofloxacin versus ciprofloxacin in the treatment of chronic bacterial prostatitis: a randomized double-blind multicenter study.

OBJECTIVES: To compare the safety and efficacy of levofloxacin with that of ciprofloxacin for the treatment of chronic bacterial prostatitis. METHODS: In a multicenter, double-blind, active-control trial, 377 men with a history of chronic bacterial prostatitis, current clinical signs and symptoms, and laboratory evidence of prostatitis were randomized to treatment with levofloxacin 500 mg once daily or ciprofloxacin 500 mg twice daily for 28 days. The primary endpoint was microbiologic efficacy in the microbiologically assessable population. The Meares-Stamey "four-glass" procedure was used to obtain prostatic secretions and urine for culture. RESULTS: A total of 377 subjects received the study drug. The clinical success rates, including cured plus improved patients, were similar (75% for levofloxacin and 72.8% for ciprofloxacin; 95% confidence interval for the difference in the success rates: -13.27 to 8.87), as were the microbiologic eradication rates (75% for levofloxacin and 76.8% for ciprofloxacin; 95% confidence interval for the difference -8.98 to 12.58). Enterococcus faecalis and Escherichia coli were the most common isolates. The 6-month relapse rates were similar for both regimens. Both levofloxacin and ciprofloxacin were well tolerated, with similar rates of adverse events. CONCLUSIONS: Levofloxacin 500 mg once daily for 28 days is as effective as ciprofloxacin 500 mg twice daily for 28 days for the treatment of chronic bacterial prostatitis. Isolation of a high proportion of gram-positive organisms, as well as gram-negative pathogens, underscores the necessity of choosing an antimicrobial agent with broad-spectrum activity.