Use of intravenous tigecycline in patients with severe Clostridium difficile infection: a retrospective observational cohort study.

There are only a limited number of antimicrobials for treating severe Clostridium difficile infection (sCDI). Tigecycline shows significant in vitro effect against C. difficile and is approved for management of complicated intra-abdominal infections. Our aim was to analyse the efficacy of tigecycline compared with standard therapy (oral vancomycin plus intravenous metronidazole) in adults treated for sCDI. A retrospective cohort study of such patients hospitalized at our department from January 2014 to December 2015 was performed. Patients receiving tigecycline monotherapy were compared with patients treated with standard therapy alone. Diagnosis and severity of CDI were determined according to guidelines of the European Society of Clinical Microbiology and Infectious Diseases (ESCMID). Primary outcome was clinical recovery, secondary outcomes were in-hospital and 90-day all-cause mortality and relapse, colectomy, and complication rates. Of the 359 patients hospitalized for sCDI, 90 (25.0%) were included, 45 in each group. Patients treated with tigecycline had significantly better outcomes of clinical cure (34/45, 75.6% vs. 24/45, 53.3%; p 0.02), less complicated disease course (13/45, 28.9% vs. 24/45, 53.3%; p 0.02), and less CDI sepsis (7/45, 15.6% vs. 18/45, 40.0%; p 0.009) compared with patients receiving standard therapy. Tigecycline usage was not associated with adverse drug reactions or need for colectomy. Rates of ileus, toxic megacolon, mortality, and relapse were similar between the two groups. Favourable outcomes suggest that tigecycline might be considered as a potential candidate for therapeutic use in cases of sCDI refractory to standard treatment.

The renaissance of polymyxins.

Polymyxins are polypeptide antibiotics, with a primary effect of membrane damaging due to their selective binding to the lipopolysaccharide of Gram-negative bacteria. Their nephro- and neurotoxic side effects limited their use, however, in the last decade the emergence of multidrug-resistant Gram-negative bacteria led to the reintroduction of polymyxins into clinical practice. This review provides an overview about the history and the latest developments of polymyxins. We describe the antimicrobial effects, pharmacodynamics, pharmacokinetics and different routes of administration. We highlight natural classic polymyxins, namely polymyxin B and E, the non-classic agents polymyxin M, S and T. Novel polymyxin chemical structure derivatives will be listed including NAB739, NAB740, NAB741 and NAB7061, that can have important therapeutical role in the future.

In vitro activity of clarithromycin in combination with other antimicrobial agents against biofilm-forming Pseudomonas aeruginosa strains.

The aim of the study was to investigate the biofilm-production of 60 Pseudomonas aeruginosa strains isolated from clinical samples and to examine the effect of different antimicrobials and their combinations with clarithromycin on biofilm-formation. The minimal inhibitory concentrations (MICs), minimal biofilm inhibitory concentrations (MBICs), and antibiotic synergy by calculating the fractional inhibitory concentration (FIC) index were determined for the following antibiotics: ceftazidime, cefepime, piperacillin/tazobactam, imipenem, meropenem, levofloxacin, ciprofloxacin, gentamicin, amikacin, tobramycin, netilmicin and clarithromycin. A total of 14 (23.3%) isolates out of 60 isolates of P. aeruginosa were biofilm positive. Cefepime, imipenem and meropenem had the lowest MIC 90 values. Piperacillin/tazobactam and clarithromycin had the highest MIC 90 values. Imipenem, meropenem, piperacillin/tazobactam and clarithromycin had the lowest MBIC 90 values. For biofilm-forming P. aeruginosa strains 2-fold to 128-fold higher MBIC values than MIC values were obtained for ceftazidime, cefepime, imipenem, amikacin and netilmicin. The MBIC was 2-fold to 512-fold lower then the MIC values in the case of piperacillin/tazobactam, ciprofloxacin, levofloxacin and clarithromycin. Synergy was generally demonstrated for clarithromycin in combination with aminoglycosides, fluoroquinolones or ceftazidime. However, surprisingly it was found that combinations of clarithromycin with carbapenems or cefepime led to an antagonistic interaction: combination of clarithromycin with imipenem, meropenem or ertapenem showed antagonism in 37.5%, 50% and 62.5% of the strains tested whereas its combination with cefepime expressed antagonism in 75% of the strains, respectively. To the best of our knowledge no one has previously described this phenomenon so far.