Protective effect of antibiotics against serious complications of common respiratory tract infections: retrospective cohort study with the UK General

Protective effect of antibiotics against serious complications of common respiratory tract infections: retrospective cohort study with the UK General Practice Research Database.

BMJ. 2007 Oct 18

Petersen I, Johnson AM, Islam A, Duckworth G, Livermore DM, Hayward AC.
UCL Centre for Infectious Disease Epidemiology, Department of Primary Care and Population Sciences, University College London, London NW3 2PQ.

OBJECTIVE: To determine the extent to which antibiotics reduce the risk of serious complications after common respiratory tract infections.

DESIGN: Retrospective cohort study.

SETTING: UK primary care practices contributing to the general practice research database. Data source 3.36 million episodes of respiratory tract infection.

MAIN OUTCOME MEASURES: Risk of serious complications in treated and untreated patients in the month after diagnosis: mastoiditis after otitis media, quinsy after sore throat, and pneumonia after upper respiratory tract infection and chest infection. Number of patients needed to treat to prevent one complication.

RESULTS: Serious complications were rare after upper respiratory tract infections, sore throat, and otitis media, and the number needed to treat was over 4000. The risk of pneumonia after chest infection was high, particularly in elderly people, and was substantially reduced by antibiotic use, with a number needed to treat of 39 for those aged >/=65 and 96-119 in younger age groups.

CONCLUSION: Antibiotics are not justified to reduce the risk of serious complications for upper respiratory tract infection, sore throat, or otitis media. Antibiotics substantially reduce the risk of pneumonia after chest infection, particularly in elderly people in whom the risk is highest.

Full text available:

British Medical Journal

Effects of tigecycline, linezolid and vancomycin on biofilms of viridans streptococci isolates from patients with endocarditis.

Effects of tigecycline, linezolid and vancomycin on biofilms of viridans streptococci isolates from patients with endocarditis.

Int J Artif Organs. 2007 Sep

Presterl E, Lassnigg A, Eder M, Reichmann S, Hirschl AM, Graninger W.
Department of Medicine I, Division of Infectious Diseases and Tropical Medicine, Medical University of Vienna, Vienna - Austria and Institute of Hygiene and Medical Microbiology, Division of Clinical Microbiology, Medical University of Vienna, Vienna - Austria.

Background: Endocarditis, and prosthetic valve endocarditis in particular, is a serious disease with high morbidity and mortality. We investigate the effects of tigecycline, linezolid and vancomycin on biofilms of viridans group streptococci (VGS) isolated from patients with definite native or prosthetic valve endocarditis.

Methods and Results: Ten of 20 VGS blood stream isolates from patients with endocarditis formed biofilms in the microtiter plate biofilm model. The minimal inhibitory concentrations (MIC) for tigecycline, linezolid and vancomycin were determined using the microdilution broth method. Biofilms were grown for 24 hours and were incubated with tigecycline, linezolid and vancomycin at increasing concentrations from 1-128x MIC of the isolate being tested. Biofilm thickness was quantified by measuring the optical density (OD) after dyeing it with crystal violet. The incubation of the biofilms with tigecycline, linezolid or vancomycin resulted in a significant reduction of OD compared to the control biofilm without antibiotic (p<0.05).>

Conclusions: In the present study on viridans streptococci isolated from patients with endocarditis, tigecycline and linezolid reduced the density of the biofilms as effectively as vancomycin. However, linezolid and vancomycin were bactericidal at higher concentrations. Linezolid and vancomycin at very high doses may be useful in the treatment of biofilm-associated diseases caused by VGS infections.

PMID: 17918125 [PubMed - as supplied by publisher]