Benefit-risk assessment of telithromycin in the treatment of community-acquired pneumonia

Comparative evaluation of small molecules reported to be inhibitors of Staphylococcus aureus biofilm formation

IMPORTANCE

Because biofilm formation is such a problematic feature of Staphylococcus aureus infections, much effort has been put into identifying biofilm inhibitors. However, the results observed with these compounds are often reported in isolation, and the methods used to assess biofilm formation vary between labs, making it impossible to assess relative efficacy and prioritize among these putative inhibitors for further study. The studies we report address this issue by directly comparing putative biofilm inhibitors using a consistent in vitro assay. This assay was previously shown to maximize biofilm formation, and the results observed with this assay have been proven to be relevant in vivo. Of the 19 compounds compared using this method, many had no impact on biofilm formation under these conditions. Indeed, only one proved effective at limiting biofilm formation without also inhibiting growth.

Synthesis and antibacterial activity of novel 2‑fluoro ketolide antibiotics with 11,12‑quinoylalkyl side chains

A series of novel 2‑fluoro ketolide antibiotics with 11,12‑quinoylalkyl side chains derived from telithromycin and cethromycin were designed and synthesized. The corresponding targets 2a-o were tested for their in vitro activities against a series of macrolide-sensitive and macrolide-resistant pathogens. Some of them showed a similar antibacterial spectrum and comparable or slightly better activity to telithromycin. Among them, compounds 2g and 2k, displayed excellent activities against macrolide-sensitive and macrolide-resistant pathogens.

Explicit definitions of potentially inappropriate prescriptions of antibiotics in older patients: a compilation derived from a systematic review

Potentially inappropriate prescriptions (PIPs) of antibiotics (antibiotic-PIPs) are generally detected by applying implicit definitions based on expert opinion. Explicit definitions are less frequently used, even though this approach would enable the automated detection of antibiotic-PIPs in electronic health records. Here, explicit definitions of antibiotic-PIPs used in studies of older adults were systematically reviewed. The MEDLINE^®, Scopus^® and Web of Science^TM core collection databases were searched with a combination of three terms and their synonyms: 'potentially inappropriate prescription' AND 'antibiotic treatment' AND 'older patients'. Following standardised selection of publications, explicit definitions of antibiotic-PIPs were extracted and were classified into infectious diseases domains and subdomains. A total of 600 search queries identified 4270 records, 93 of which were selected for review. A total of 160 mentions of antibiotic-PIPs were found, corresponding to 62 distinct definitions in 19 infectious diseases domains. Nearly one-half of the definitions were related to upper respiratory tract infections (n = 11 definitions; 17.7%), lower respiratory tract infections (n = 8; 12.9%) and drug-drug interactions (n = 11; 17.7%). Almost 75% of definitions (n = 46) were mentioned in a single study only. Only three definitions concerned critically important antibiotics such as third-generation cephalosporins and fluoroquinolones. This systematic review identified 62 explicit definitions of antibiotic-PIPs. Most of the definitions were not found in more than one study and they varied in the degree of precision. We advocate the implementation of an expert consensus on explicit definitions of antibiotic-PIPs that correspond to today's challenges in public health.

Evaluation of macrolides for possible use against multidrug-resistant Mycobacterium tuberculosis

Multidrug-resistant tuberculosis (MDR-TB) is a major global health problem. The loss of susceptibility to an increasing number of drugs behoves us to consider the evaluation of non-traditional anti-tuberculosis drugs.

Clarithromycin, a macrolide antibiotic, is defined as a group 5 anti-tuberculosis drug by the World Health Organization; however, its role or efficacy in the treatment of MDR-TB is unclear. A systematic review of the literature was conducted to summarise the evidence for the activity of macrolides against MDR-TB, by evaluating in vitro, in vivo and clinical studies. PubMed and Embase were searched for English language articles up to May 2014.

Even though high minimum inhibitory concentration values are usually found, suggesting low activity against Mycobacterium tuberculosis, the potential benefits of macrolides are their accumulation in the relevant compartments and cells in the lungs, their immunomodulatory effects and their synergistic activity with other anti-TB drugs.

A future perspective may be use of more potent macrolide analogues to enhance the activity of the treatment regimen.

Investigating the entire course of telithromycin binding to Escherichia coli ribosomes

Applying kinetics and footprinting analysis, we show that telithromycin, a ketolide antibiotic, binds to Escherichia coli ribosomes in a two-step process. During the first, rapidly equilibrated step, telithromycin binds to a low-affinity site (K_T = 500 nM), in which the lactone ring is positioned at the upper portion of the peptide exit tunnel, while the alkyl–aryl side chain of the drug inserts a groove formed by nucleotides A789 and U790 of 23S rRNA. During the second step, telithromycin shifts slowly to a high-affinity site (K_T*= 8.33 nM), in which the lactone ring remains essentially at the same position, while the side chain interacts with the base pair U2609:A752 and the extended loop of protein L22. Consistently, mutations perturbing either the base pair U2609:A752 or the L22-loop hinder shifting of telithromycin to the final position, without affecting the initial step of binding. In contrast, mutation Lys63Glu in protein L4 placed on the opposite side of the tunnel, exerts only a minor effect on telithromycin binding. Polyamines disfavor both sequential steps of binding. Our data correlate well with recent crystallographic data and rationalize the changes in the accessibility of ribosomes to telithromycin in response to ribosomal mutations and ionic changes.