Complicated urinary infection in spinal injury patients: fleroxacin compared with ciprofloxacin

Pharmacokinetic Characteristics of Antimicrobials and Optimal Treatment of Urosepsis

Urosepsis accounts for approximately 25% of all sepsis cases and may develop from a community-acquired or nosocomial urinary tract infection (UTI). Nevertheless, the underlying UTI is almost exclusively a complicated one with involvement of the parenchymatous urogenital organs (e.g. kidneys, prostate) and mostly associated with any kind of obstructive uropathy. If urosepsis originates from a nosocomial infection, a broad spectrum of Gram-negative and Gram-positive pathogens have to be expected, which are often multiresistant. In urosepsis, as in other types of sepsis, the severity of sepsis depends mostly upon the host response. The treatment of urosepsis follows the generally accepted rules of the 'Surviving Sepsis' campaign guidelines. Early normalisation of blood pressure and early adequate empirical antibacterial therapy with optimised dosing are equally important to meet the requirements of early goal-directed therapy. In most cases of urosepsis, early control of the infectious focus is possible and as important. Optimal supportive measures need to follow the early phase of resuscitation. To lower mortality from urosepsis, an optimal interdisciplinary approach between intensive care, anti-infective therapy and urology is essential, assisted by easy access to the necessary laboratory and imaging diagnostic procedures. Although most antibacterials achieve high urinary concentrations, there are several unique features of complicated UTI, and thus urosepsis, that influence the activity of antibacterial substances: (i) renal pharmacokinetics differ in unilateral and bilateral renal impairment and in unilateral and bilateral renal obstruction; (ii) variations in pH may influence the activity of certain antibacterials; and (iii) biofilm infection is frequently found under these conditions, which may increase the minimal inhibitory concentrations (MIC) of the antibacterials at the site of infection by several hundred folds. Assessment of antibacterial pharmacodynamic properties in such situations should take into account not only the MIC as determined in vitro and the plasma concentrations of the free (unbound) drug, which are the guiding principles for many infections, but also the actual renal excretion and urinary bactericidal activity of the antibacterial substance. In the treatment of urosepsis, it is important to achieve optimal exposure to antibacterials both in plasma and in the urinary tract. The role of drugs with low renal excretion rates is therefore limited. Since urosepsis quite often originates from catheter-associated UTI and urological interventions, optimal catheter care and optimal strategies to prevent nosocomial UTI may be able to reduce the frequency of urosepsis.

Current challenges in the treatment of complicated urinary tract infections and prostatitis

Serious urinary tract infections (UTIs) and acute bacterial prostatitis in adults cause significant morbidity and economic burden. Chronic bacterial prostatitis is a rather rare condition seen in urological practice, however, in certain occasions difficult to treat. In this paper, we review the bacterial etiologies and the resistance patterns found in adults with serious UTIs and bacterial prostatitis, and discuss considerations for selecting optimal antimicrobial therapy. The role of fluoroquinolones as targeted therapy for serious UTIs is highlighted. The use of effective antimicrobial therapy is the foundation of management of serious UTIs and bacterial prostatitis. Selection of the optimal antimicrobial agent must take into account patient-specific factors; infection characteristics (e.g., severity, community- vs. institutional- or hospital-acquired, need for IV agent, UTI, prostatitis); local resistance pattern; pharmacokinetic and pharmacodynamic principles; and cost. Fluoroquinolones are among the alternatives for empirical antibiotic treatment of serious UTIs and acute bacterial prostatitis. In serious UTIs activity of the antimicrobial agent against Pseudomonas aeruginosa needs to be taken into account. In chronic bacterial prostatitis fluoroquinolones are the first choice because of their favourable pharmacokinetic properties at the site of infection. Targeted antimicrobial therapy--emphasising the correct antibacterial spectrum and correct dosage--is likely to provide important benefits, such as reduced morbidity and associated costs, reduced emergence of resistance and maintenance of class efficacy.

Role of fluoroquinolones in the treatment of serious bacterial urinary tract infections

Serious urinary tract infections (UTIs) in adults--defined as acute complicated UTIs or pyelonephritis requiring initial intravenous antimicrobials and/or hospitalisation and nosocomial infections--cause significant morbidity and economic burden. In the US, UTIs are responsible for nearly 7 million outpatient physician office visits, 1 million emergency room visits and over 100 000 hospital admissions annually. Complicated UTIs often affect patients with underlying functional, metabolic or anatomical defects of the urinary tract, whereas most nosocomial UTIs (~80%) are related to short- or long-term catheterisation. Serious UTIs are often difficult to treat because infection involves a diverse array of Gram-negative and Gram-positive bacteria, coupled with increasing antimicrobial resistance in some uropathogens, and a higher rate of recurrent infections. Although Escherichia coli remains a common aetiology (< or =60%), other Enterobacteriaceae, Gram-negative bacilli (e.g. Pseudomonas aeruginosa), and Gram-positive bacteria (e.g. Staphylococcus aureus) are frequently isolated. Patients with long-term catheterisation have UTIs typically caused by organisms that produce biofilms making eradication even more difficult. Overall, aetiology and resistance patterns are not predictable for those with serious UTIs, necessitating confirmation by culture and susceptibility testing.Numerous intravenous and oral antimicrobial treatment options are available and the majority of patients with serious UTIs will need initial intravenous therapy because of the possibility of bacteraemia/sepsis or impaired gastrointestinal absorption. Many experts concur that empirical therapy for the institutionalised or hospitalised patient with a serious UTI should include an intravenous antipseudomonal agent because of an increased risk of urosepsis. While state-of-the-art treatment guidelines are lacking for these infections, targeted therapy should be initiated once susceptibility data are known. The use of targeted therapy--emphasising the "correct antibacterial spectrum" and pharmacodynamic superiority--is likely to provide important benefits (e.g. reduced morbidity and associated costs, reduced emergence of resistance). Agents commonly prescribed include aminoglycosides, beta-lactam/beta-lactamase inhibitor combinations, imipenem, advanced-generation cephalosporins and fluoroquinolones. Fluoroquinolones are often recommended when conventional agents have failed or are less desirable (e.g. toxicity/hypersensitivity concerns), or when resistance is high. Several pivotal clinical trials support the use of fluoroquinolones for serious UTIs with most experience garnered with ciprofloxacin, including a new once-daily extended-release tablet formulation.Treatment of patients with serious UTIs remains challenging. Physicians should choose empirical therapy based on patient demographics/medical history, presumed aetiology and local resistance patterns until more definitive guidelines become available.

Integrating fluoroquinolones into the hospital formulary

With the increasing availability of new agents, selection of fluoroquinolones for formulary inclusion can be difficult. Appropriate evaluation of the important characteristics (pharmacokinetic and pharmacodynamic properties, antimicrobial activity, efficacy, tolerability, cost) of these agents should allow selection of the most cost-effective ones. Evidence from in vitro studies and clinical trials indicates differences exist among fluoroquinolones, especially in terms of activity against gram-positive, aerobic organisms. For selected clinical situations, it may be important to choose an agent that is available in both intravenous and oral formulations. Comparative drug costs, as well as costs associated with potential clinical failure and adverse events, should be evaluated carefully. Dosage regimens should be considered, as shorter durations of therapy and less frequent dose administration may lead to reduced labor costs and increased patient compliance, thereby improving effectiveness and economic efficiency.