Do high doses of quinolones decrease the emergence of antibacterial resistance? A systematic review of data from comparative clinical trials

Optimization of Antimicrobial Treatment to Minimize Resistance Selection

Optimization of antimicrobial treatment is a cornerstone in the fight against antimicrobial resistance. Various national and international authorities and professional veterinary and farming associations have released generic guidelines on prudent antimicrobial use in animals. However, these generic guidelines need to be translated into a set of animal species- and disease-specific practice recommendations. This article focuses on prevention of antimicrobial resistance and its complex relationship with treatment efficacy, highlighting key situations where the current antimicrobial drug products, treatment recommendations, and practices may be insufficient to minimize antimicrobial selection. The authors address this topic using a multidisciplinary approach involving microbiology, pharmacology, clinical medicine, and animal husbandry. In the first part of the article, we define four key targets for implementing the concept of optimal antimicrobial treatment in veterinary practice: (i) reduction of overall antimicrobial consumption, (ii) improved use of diagnostic testing, (iii) prudent use of second-line, critically important antimicrobials, and (iv) optimization of dosage regimens. In the second part, we provided practice recommendations for achieving these four targets, with reference to specific conditions that account for most antimicrobial use in pigs (intestinal and respiratory disease), cattle (respiratory disease and mastitis), dogs and cats (skin, intestinal, genitourinary, and respiratory disease), and horses (upper respiratory disease, neonatal foal care, and surgical infections). Lastly, we present perspectives on the education and research needs for improving antimicrobial use in the future.

Central venous catheter infections and antibiotic therapy during long-term home parenteral nutrition: an 11-year follow-up study

BACKGROUND

Catheter-related bloodstream infections are a serious and common complication in patients receiving home parenteral nutrition (HPN).

METHODS

Prevalence of infections, type of agents, and effectiveness of antibiotic therapy were evaluated in 296 patients (133 males, 163 females; mean age 58.2 +/- 13.5 years) receiving HPN for at least 3 months, from January 1995 to December 2006. Patients underwent 99,969 (331 +/- 552; minimum 91, maximum 4353) days of catheterization, corresponding to 93,236 (311 +/- 489; minimum 52, maximum 4353) days of HPN.

RESULTS

Fifty-two patients (24 males and 28 females; 35 oncological and 17 nononcological) were diagnosed with 169 infections. The overall corresponding infection rate was 2.0 per 1000 days of catheterization, with a progressive, regular decrease with time. In 30 cases, immediate central venous catheter removal was necessary. Infections were eradicated in 103 of 139 (74%) cases. As to the most common causative agent, 86 (51%) infections were due to Staphylococcus epidermidis. Of these, 64 were treated from 1995 to 2004, 57 of them (89%) successfully; 22 were treated from 2005 onward, only 7 of them (32%) successfully.

CONCLUSIONS

Although the global infection rate has progressively decreased over the years, S epidermidis has shown an alarming increase in resistance to antibiotic treatment in the last 2 years, suggesting the need for strategies to prevent central venous catheter infection.

The newer fluoroquinolones

Clinicians have enthusiastically used fluoroquinolones owing to their good safety profile and wide range of indications. This article reviews fluoroquinolone pharmacology, pharmacodynamic principles, and fluoroquinolone resistance mechanisms, highlighting recent trends in the epidemiology of fluoroquinolone resistance among gram-negative organisms and Streptococcus pneumonia. Important fluoroquinolone safety concerns are discussed, along with indications for the most commonly used fluoroquinolones-ciprofloxacin, levofloxacin, and moxifloxacin.

Pharmacokinetics and pharmacodynamics of antibacterial agents

This article reviews pharmacodynamics of antibacterial drugs, which can be used to optimize treatment strategies, prevent emergence of resistance and rationalize the determination of antimicrobial susceptibility. Important pharmacodynamic concepts include the requirements for bactericidal therapy for endocarditis and meningitis, for synergistic combinations to treat enterococcal endocarditis or to shorten the course of antimicrobial therapy, for obtaining maximal plasma concentration/minimal inhibitory concentration (MIC) ratios that are greater than 10 or 24 hour-area under the plasma concentration curve (AUC)/MIC ratios that are greater than 100-125 for concentration-dependent agents against gram-negative bacilli and 25-35 against Streptococcus pneumoniae, and for obtaining percent of time that drug levels are greater than the MIC that is at least 40% to 50% of the dosing interval for time-dependent agents.