Optimizing rapid diagnostics and diagnostic stewardship in Gram-negative bacteremia

Antimicrobial resistance remains a high global concern, as it is associated with prolonged hospitalizations, increased morbidity and mortality, and escalating healthcare-related costs. Rapid diagnostic technology (RDT) has become the cornerstone in achieving prompt blood culture results providing a quicker initiation of optimal therapy, decreased mortality, and decreased spread of resistance. To maximize the benefits of RDTs, antimicrobial stewardship programs must implement a diagnostic stewardship (DS) subgroup to optimize communication, education, and interpretation of RDT results within the healthcare system. The DS subgroup is necessary to evaluate the technologies available, better integrate the selected technologies into the healthcare system, and develop innovative and appropriate use to improve patient outcomes.     

Omics of antimicrobials and antimicrobial resistance

Introduction: The development of new antimicrobials has become an urgent priority because of a global challenge emerging from the rise of antimicrobial resistant pathogens.

Areas covered: In this review, the authors discuss the opportunities offered by modern omics approaches to address the challenge and the use of this approach in antimicrobial development. Specifically, the authors focus on the role of omics technologies and bioinformatics for the revelation of the effects of antimicrobials in a variety of microbial cellular processes, as well as the identification of potential cellular targets, the mechanisms of antimicrobial resistance, and the development of new antimicrobials.

Expert opinion: Prevention of antimicrobial resistance does not only depend on rational drug design such as narrow-spectrum antimicrobials but on several factors. It is the opinion of the authors that the use of a multi-omics bioinformatics approach should become an integral part of antimicrobial drug discovery as well as in the prevention of antimicrobial resistance.     

Molecular epidemiology and antimicrobial resistance mechanisms of Campylobacter coli from diarrhoeal patients and broiler carcasses in Belgium

The aim of this study was to better understand the molecular epidemiology of Campylobacter coli isolated from multiple sources in Belgium, by studying the genotypic diversity and antimicrobial resistance phenotypes and resistance mechanisms of 59 C. coli isolates. Isolates from broiler carcasses and human cases were genotyped using multilocus sequence typing (MLST), porA typing, flagellin gene A restriction fragment length polymorphism (flaA–RFLP) typing, and by PCR binary typing (P‐BIT). Thirty‐two MLST sequence types, 24 flaA types, 31 porA alleles, and 29 P‐BIT types were identified among the screened isolates. Some types and alleles were shared among strains recovered from both broiler carcasses and diarrhoeal patients. Both porA typing and MLST revealed a similar discriminatory power (0.969), which was the highest discriminatory power when compared to other methods. Minimum inhibitory concentrations against seven different antibiotics (ciprofloxacin, chloramphenicol, nalidixic acid, streptomycin, tetracycline, gentamicin, and erythromycin) were analysed. Strains were most frequently resistant to tetracycline (81.4%), followed by: ciprofloxacin and nalidixic acid (76.3%); streptomycin (33.9%); erythromycin (27.1%); and chloramphenicol (3.4%). All isolates were sensitive to gentamicin. Multidrug resistance was observed in 24 of 59 C. coli isolates (40.7%). Molecular screening of antimicrobial resistance mechanisms revealed the predominance of the gyrA T86I substitution among ciprofloxacin‐ and nalidixic acid‐resistant isolates, the tet(O) gene among tetracycline‐resistant isolates and the 23S rRNA A2075G mutation among erythromycin‐ resistant isolates. Furthermore, some erythromycin‐resistant isolates harboured a diverse array of resistance mechanisms, including the presence of ermB, 23S rRNA A2074G mutation, and point mutations the rplD and rplV ribosomal genes, and the cmeABC multidrug efflux pump genes.     

Lefamulin: a promising new pleuromutilin antibiotic in the pipeline

Introduction: Community-acquired bacterial pneumonia (CABP) represents a significant clinical and financial burden within infectious disease. In the advent of increasing resistance from bacteria such as Streptococcus pneumoniae to available antibiotic therapies, there is a need for new drugs with novel mechanisms to treat such infections.

Areas covered: Lefamulin, the first semi-synthetic pleuromutilin for systemic administration, is nearing completion of Phase III studies for CABP; the manufacturer plans to file for a new drug application (NDA) in Q4 2018. This paper details available data on the pharmacokinetic, pharmacodynamic, in vitro and clinical data of the drug to date, derived from published literature, conference posters and data provided by the manufacturer.

Expert commentary: Lefamulin offers a unique spectrum of activity as a potential monotherapy treatment agent for CABP and alternative to fluoroquinolone therapy. The drug displays potent activity against several pathogens common in both acute bacterial skin and skin structure infections (ABSSSIs) and CABP, and a lack of cross-resistance with other antibiotic classes for S. pneumoniae and Staphylococcus aureus. Lefamulin has met predefined noninferiority endpoints of clinical response for CABP compared to moxifloxacin ± linezolid in two Phase III trials (LEAP 1 and 2) and presents an alternative therapy for CABP.     

Efficacy of the antimicrobial peptide TP4 against Helicobacter pylori infection: in vitro membrane perturbation via micellization and in vivo suppression of host immune responses in a mouse model

Helicobacter pylori infection is marked by a strong association with various gastric diseases, including gastritis, ulcers, and gastric cancer. Antibiotic treatment regimens have low success rates due to the rapid occurrence of resistant H. pylori strains, necessitating the development of novel anti-H. pylori strategies. Here, we investigated the therapeutic potential of a novel peptide, Tilapia Piscidin 4 (TP4), against multidrug resistant gastric pathogen H. pylori, based on its in vitro and in vivo efficacy. TP4 inhibited the growth of both antibiotic-sensitive and -resistant H. pylori (CagA⁺, VacA⁺) via membrane micelle formation, which led to membrane depolarization and extravasation of cellular constituents. During colonization of gastric tissue, H. pylori infection maintains high T regulatorysubsets and a low Th17/Treg ratio, and results in expression of both pro- and anti-inflammatory cytokines. Treatment with TP4 suppressed Treg subset populations and pro- and anti-inflammatory cytokines. TP4 restored the Th17/Treg balance, which resulted in early clearance of H. pylori density and recovery of gastric morphology. Toxicity studies demonstrated that TP4 treatment has no adverse effects in mice or rabbits. The results of this study indicate that TP4 may be an effective and safe monotherapeutic agent for the treatment of multidrug resistant H. pylori infections.