Evaluation of FDA Boxed Warning on Prescribing Patterns of Fluoroquinolones for Uncomplicated Urinary Tract Infections.

Background: Little is known regarding the impact of the Food and Drug Administration (FDA) boxed warning on prescribing rates of fluoroquinolone (FQ) antibiotics in the outpatient setting. Objective: The primary objective of this study was to evaluate the 2016 FDA boxed warning update on FQ prescribing rates for uncomplicated urinary tract infection (uUTI). Methods: This was a single-center retrospective cohort study conducted at 6 family medicine practices, including women aged 18 to 65 years with an outpatient visit for uUTI from January 1, 2016, to December 31, 2016. Results: A total of 436 patients met inclusion. FQs were prescribed in 38% of patients before the FDA boxed warning and in 30% of patients after (8% reduction). Non-FQ prescribing had a corresponding 8% increase, comprising 62% of uUTI prescribing before the FDA boxed warning and 70% after (P = 0.08). The likelihood of being prescribed a FQ was not significantly different following release of the FDA boxed warning (adjusted odds ratio = 0.67 [95% CI = 0.41-1.10]). Variables significantly associated with an increase in FQ prescribing based on logistic regression were age ≥58 years and chronic kidney disease. Concordance of antibiotic prescribing with the Infectious Diseases Society of America clinical practice guidelines for uUTI was low, and the incidence of treatment failure was low. Conclusion and Relevance: The 2016 FDA boxed warning was not significantly associated with decreased FQ prescribing for uUTI across a large academic family medicine practice. Methods to improve education and disseminate FDA warnings in practice are needed.

Bezlotoxumab for the Prevention of Clostridium difficile Recurrence.

OBJECTIVE: To review the pharmacology, pharmacokinetics, pharmacodynamics, clinical efficacy, tolerability, dosing, and administration of bezlotoxumab (BEZ), as well as its place in the prevention of Clostridium difficile infection (CDI) recurrence. DATA SOURCES: A search of PubMed and Google Scholar using the terms "bezlotoxumab," "CDB1," "MDX-1388," and "MK-6072" was performed. The manufacturer's website was also reviewed to further identify relevant information. STUDY SELCTION: All English-language articles from 2006 to May 2017 appearing in these searches were reviewed for relevance to this paper. In addition, their bibliographies were reviewed to identify any articles not identified in the searches. DATA SYNTHESIS: BEZ is a human monoclonal antibody that binds to Clostridium difficile toxin B. It is approved by the Food and Drug Administration to reduce CDI recurrence in adult patients who are receiving antibiotic therapy for CDI and are at high risk for CDI recurrence. It is given as a single dose of 10 mg/kg via an intravenous infusion. It is eliminated by catabolism. Phase III clinical trials demonstrated that BEZ was associated with significantly lower rates of CDI recurrence, compared with placebo. The most common adverse events reported during clinical trials were diarrhea and nausea. There is a warning regarding the use of BEZ in patients with a history of congestive heart failure. The most common adverse reactions associated with BEZ are nausea, pyrexia, and headache. CONCLUSION: BEZ has been proven safe and effective in preventing CDI recurrence. Given its high cost, it should be reserved for patients at high risk for CDI recurrence.

A Baker's Dozen of Top Antimicrobial Stewardship Intervention Publications in 2018.

With an increasing number of antimicrobial stewardship-related articles published each year, attempting to stay current is challenging. The Southeastern Research Group Endeavor (SERGE-45) identified antimicrobial stewardship-related peer-reviewed literature that detailed an actionable intervention for 2018. The top 13 publications were selected using a modified Delphi technique. These manuscripts were reviewed to highlight the actionable intervention used by antimicrobial stewardship programs to provide key stewardship literature for teaching and training as well as to identify potential intervention opportunities within one's institution.

What Is Old Is New Again: Delafloxacin, a Modern Fluoroquinolone.

Delafloxacin is a new fluoroquinolone antimicrobial approved for the treatment of acute bacterial skin and skin structure infections (ABSSSIs) in adults using dosage regimens of 300 mg intravenously every 12 hours, 450 mg orally every 12 hours, or switching from intravenous to oral regimens for a 5- to 14-day treatment duration. Dosage adjustments in patients with severe renal dysfunction (estimated glomerular filtration rate [eGFR] = 15-29 ml/min/1.73 m2 ) are not required for oral doses but should be decreased to 200 mg intravenously every 12 hours in patients requiring parenteral therapy. Due to insufficient data, use of delafloxacin is not recommended for patients on hemodialysis or with end-stage renal disease (eGFR < 15 ml/min/1.73 m2 ). Delafloxacin works through inhibition of DNA gyrase (topoisomerase II) and topoisomerase IV, which are essential enzymes for bacterial DNA transcription, replication, repair, and recombination and exhibits bactericidal activity against gram-positive and gram-negative organisms through a concentration-dependent matter. Delafloxacin has a very broad spectrum of activity against atypical, anaerobic, and resistant gram-negative and gram-positive bacteria, including methicillin-resistant Staphylococcus aureus and Pseudomonas aeruginosa. During phase 3 trials, the most common side effects associated with delafloxacin were gastrointestinal (nausea, diarrhea). Unlike other fluoroquinolones, there does not seem to be a risk of QTc prolongation or phototoxicity with delafloxacin. The availability of both parenteral and oral formulations for delafloxacin distinguishes it from many of the currently available agents approved for ABSSSIs. Phase 3 studies for the treatment of respiratory infections are currently under way, and future results of these studies will further help delineate the role of delafloxacin.

Mycobacterium abscessus Complex Infections: A Retrospective Cohort Study.

BACKGROUND: Infections caused by Mycobacterium abscessus group strains are usually resistant to multiple antimicrobials and challenging to treat worldwide. We describe the risk factors, treatment, and clinical outcomes of patients in 2 large academic medical centers in the United States. METHODS: A retrospective cohort study of hospitalized adults with a positive culture for M. abscessus in Miami, Florida (January 1, 2011, to December 31, 2014). Demographics, comorbidities, the source of infection, antimicrobial susceptibilities, and clinical outcomes were analyzed. Early treatment failure was defined as death and/or infection relapse characterized either by persistent positive culture for M. abscessus within 12 weeks of treatment initiation and/or lack of radiographic improvement. RESULTS: One hundred eight patients were analyzed. The mean age was 50.81 ± 21.03 years, 57 (52.8%) were females, and 41 (38%) Hispanics. Eleven (10.2%) had end-stage renal disease, 34 (31.5%) were on immunosuppressive therapy, and 40% had chronic lung disease. Fifty-nine organisms (54.6%) were isolated in respiratory sources, 21 (19.4%) in blood, 10 (9.2%) skin and soft tissue, and 9 (8.3%) intra-abdominal. Antimicrobial susceptibility reports were available for 64 (59.3%) of the patients. Most of the isolates were susceptible to clarithromycin, amikacin, and tigecycline (93.8%, 93.8%, and 89.1%, respectively). None of the isolates were susceptible to trimethoprim/sulfamethoxazole, and only 1 (1.6%) was susceptible to ciprofloxacin. Thirty-six (33.3%) patients early failed treatment; of those, 17 (15.7%) died while hospitalized. On multivariate analysis, risk factors significantly associated with early treatment failure were disseminated infection (odds ratio [OR], 11.79; 95% confidence interval [CI], 1.53-81.69; P = .04), acute kidney injury (OR, 6.55; 95% CI, 2.4-31.25; P = .018), organ transplantation (OR, 2.37; 95% CI, 2.7-23.1; P = .005), immunosuppressive therapy (OR, 2.81; 95% CI, 1.6-21.4; P = .002), intravenous amikacin treatment (OR, 4.1; 95% CI, 0.9-21; P = .04), clarithromycin resistance (OR,79.5; 95% CI, 6.2-3717.1, P < .001), and presence of prosthetic device (OR, 5.43; 95% CI, 1.57-18.81; P = .008). Receiving macrolide treatment was found to be protective against early treatment failure (OR, 0.13; 95% CI, 0.002-1.8; P = .04). CONCLUSIONS: Our cohort of 108 M. abscessus complex isolates in Miami, Florida, showed an in-hospital mortality of 15.7%. Most infections were respiratory. Clarithromycin and amikacin were the most likely agents to be susceptible in vitro. Resistance to fluoroquinolone and trimethoprim/sulfamethoxazole was highly common. Macrolide resistance, immunosuppression, and renal disease were significantly associated with early treatment failure.

Elvitegravir for the treatment of HIV.

INTRODUCTION: Current antiretrovirals (ARVs) have demonstrated the ability to prolong the life of an HIV infected individual via suppression of the virus and subsequent restoration of immune function. Despite significant advancement, there remains an opportunity for improvement. One ARV that attempts to fill global HIV therapeutic needs by balancing convenience, safety, and efficacy is elvitegravir (EVG). Areas covered: Using MEDLINE/PubMed, a literature search was conducted for published articles on the safety and efficacy of EVG in the treatment of HIV infection. Expert opinion: EVG offers clinicians a convenient choice for HIV-positive patients that is safe and effective for both treatment-naïve and experienced patients, as well as an option for regimen simplification in virologically suppressed patients. EVG is conveniently co-formulated in fixed dose combination tablets to be taken once daily with food. EVG does not require dose adjustment for patients with severe renal impairment or mild to moderate liver disease. Importantly, EVG requires co-administration with a pharmacokinetic enhancer (i.e., ritonavir or cobicistat) in order to achieve therapeutic levels and facilitate once daily dosing. As a consequence, clinicians must carefully review concomitant medications and navigate potential drug-drug interactions mediated through potent inhibition of cytochrome P450 3A enzymes by ritonavir and cobicistat.

Cobicistat: Review of a Pharmacokinetic Enhancer for HIV Infection.

PURPOSE: This article reviews the clinical pharmacology, pharmacodynamic and pharmacokinetic (PK) properties, clinical efficacy and tolerability, drug interactions, and dosing and administration of cobicistat. METHODS: Searches of MEDLINE and International Pharmaceutical Abstracts from 1964 to February 2015 were conducted using the search terms cobicistat and GS-9350. Relevant information was extracted from the identified clinical trials and review articles. Abstracts from the Conference on Retroviruses and Opportunistic Infections (2014-2015) and the Interscience Conference on Antimicrobial Agents and Chemotherapy (2013-2014) were also searched. FINDINGS: Cobicistat is a PK enhancer lacking antiviral activity that, via selective cytochrome P-450 (CYP) 3A inhibition, inhibits the metabolism of certain antiretroviral medications and is used for prolonging their effect. Cobicistat has been studied as a booster of elvitegravir, a second-generation integrase inhibitor, and of the protease inhibitors atazanavir and darunavir. Data on its clinical efficacy and tolerability have been presented in 2 Phase II trials and in 9 Phase III trials, which reported durable efficacy in terms of achievement of sustained suppression of HIV-1 RNA levels to <50 copies/mL for at least 48 weeks. Cobicistat was generally well-tolerated in these studies. Cobicistat may increase serum creatinine levels via the inhibition of proximal renal tubular cell transporters and thus reduce estimated glomerular filtration rate, although it does not appear to affect actual glomerular filtration rate. Given the potent CYP3A inhibition by cobicistat, its coadministration with drugs metabolized by CYP3A may result in increased plasma concentrations of such agents. Moreover, as cobicistat is metabolized predominantly by CYP3A, plasma concentrations may increase or decrease on coadministration with CYP3A inhibitors or inducers, respectively. IMPLICATIONS: With potent durability through 48 weeks, a tolerability profile comparable to other first- and second-line antiretroviral therapies, and a convenient dosing schedule with low daily pill burden in fixed-dose combination tablets, cobicistat is a potential addition to the management of HIV infection as a PK enhancer. However, the effects of cobicistat on serum creatinine and its considerable drug-interaction potential may warrant additional monitoring.

Bedaquiline: a novel antitubercular agent for the treatment of multidrug-resistant tuberculosis.

Bedaquiline is a diarylquinoline antitubercular drug with a novel mechanism of action against Mycobacterium tuberculosis. Bedaquiline works by inhibiting bacterial adenosine triphosphate (ATP) synthase and represents the first novel class of antituberculosis agents in more than 40 years. Bedaquiline is indicated for the treatment of multidrug-resistant tuberculosis (MDR TB) in combination with at least three other antitubercular drugs when no other effective regimen is available. The recommended bedaquiline dosage is 400 mg orally once/day for 2 weeks followed by 200 mg orally 3 times/week for 22 weeks. Bedaquiline should be administered with food, which increases the bioavailability 2-fold. Bedaquiline is metabolized by cytochrome P450 isoenzyme 3A4 and is impacted by both inducers and inhibitors of this isoenzyme. Concentration-dependent bactericidal activity was observed in laboratory and murine studies. Accelerated approval was granted in the United States and European Union based on the results of two phase IIb clinical studies that used sputum culture clearance as a surrogate end point for clinical efficacy. These studies showed greater sputum culture clearance up to week 24 for the bedaquiline group compared with placebo. Common adverse events in clinical trials included nausea, arthralgia, and headache. Serious adverse events included elevated serum transaminase levels and rate-corrected QT-interval prolongation. Unexplained higher mortality was seen in patients receiving bedaquiline versus those receiving placebo. Bedaquiline is a novel agent with a unique mechanism of action and has the potential to meet a great need in patients with MDR TB who have no other treatment options. Due to safety concerns and limited clinical information, phase III trials are needed to fully determine its place in therapy.