Documentation of vancomycin-resistant Staphylococcus aureus (VRSA) among children with atopic dermatitis in the Qassim region, Saudi Arabia.

Sept 2012

Alzolibani AA, Al Robaee AA, Al Shobaili HA, Bilal JA, Issa Ahmad M, Bin Saif G.

Source

Department of Dermatology, College of Medicine, Qassim University, Buraydah 51477, Saudi Arabia. azolibani@yahoo.com.

Abstract

INTRODUCTION:

Staphylococcus aureus is known as a common pathogen in atopic dermatitis. A methicillin-resistant S. aureus strain with reduced susceptibility to vancomycin (VISA/VRSA) is increasing worldwide. The aims of this study were to evaluate the antibiotic-susceptibility pattern of S. aureus isolated from children with atopic dermatitis and to identify the occurrence of resistance to glycopeptide antibiotics.

METHODS:

Swabs were collected from atopic dermatitis skin lesions of 80 children being treated at dermatology clinics whose ages ranged from 6 months to 15 years in the period from March 2009 to February 2010. Isolates were studied with an antibiogram for an antibiotic-susceptibility test. The selected antibiotics were the usually administered antimicrobials at dermatological clinics in Buraydah (Qassim, Saudi Arabia). Results were determined as minimal inhibitory concentration (MIC) using the Vitek system.

RESULTS:

Thirty S. aureus isolates showed resistance to streptomycin (100%), benzylpenicillin and ampicillin (96.7%), and oxacillin (90%). S. aureus resistance to trimethoprim/sulfamethoxazole, tigecycline, and vancomycin was 63.3%, 83.3%, and 53.3%, respectively. Resistance to linezolid was less, at 5.7%.

CONCLUSIONS:

Strains of MRSA with decreasing susceptibility to vancomycin were documented in the Qassim region of Saudi Arabia. Other studies will be required on VISA/VRSA strains concerning phenotypic and genotypic characterization.

PubMed

Redesign of Glycopeptide Antibiotics - Back to the Future.

Feb 2012

Boger DL, James RC, Pierce JG, Okano A, Xie J.

Abstract

The glycopeptide antibiotics are the most important class of drugs used in the treatment of resistant bacterial infections including those caused by methicillin-resistant Staphylococcus aureus (MRSA). After more than 50 years of clinical use, the emergence of glycopeptide resistant Gram-positive pathogens such as vancomycin-resistant enterococci (VRE) and vancomycin-resistant Staphylococcus aureus (VRSA) presents a serious global challenge to public health at a time few newantibiotics are being developed. This has led to renewed interest in the search for additional effective treatments including the development of new derivatives of the glycopeptide antibiotics. General approaches have been explored for modifying glycopeptide antibiotics, typically through the derivatization of the natural products themselves or more recently through chemical total synthesis. In this Perspective, we consider recent efforts to redesign glycopeptide antibiotics for the treatment of resistant microbial infections, including VRE and VRSA, and examine their potential for providing an even more powerful class of antibiotics that are even less prone to bacterial resistance.

ACS Chemical Biology

Comparative antibacterial effects of daptomycin, vancomycin and teicoplanin studied in an in vitro pharmacokinetic model of infection.

Comparative antibacterial effects of daptomycin, vancomycin and teicoplanin studied in an in vitro pharmacokinetic model of infection
J Antimicrob Chemother. 2009 Sep 16

Bowker KE, Noel AR, Macgowan AP.
Bristol Centre for Antimicrobial Research and Evaluation (BCARE), Department of Microbiology, Southmead Hospital, Westbury-on-Trym, Bristol BS10 5NB, UK.

* Corresponding author. Tel: +44-(0)1179-9595654; Fax: +44-(0)117-9593217; E-mail: karen.bowker@nbt.nhs.uk

Objectives
To compare the antibacterial effects (ABEs) of the free (f) drugs daptomycin, vancomycin and teicoplanin against methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant S. aureus (VRSA), using high and low inocula in a pharmacokinetic in vitro model. To determine the daptomycin fAUC/MIC ratio for a static effect and 3 log reduction in viable count and relate this target to the clinical breakpoint.

Methods
Five clinical MRSA isolates held at Southmead Hospital were used (SMH 15841, SMH 40289, SMH 40275, SMH 33922 and SMH 33024) together with a VRSA isolate (SMH 19898); inocula of 10(6) and 10(8) cfu/mL were used. Daptomycin (6 mg/kg once daily), vancomycin (1 g twice daily) and teicoplanin (400 mg once daily) regimens were simulated. ABEs were measured using the 24 h area-under-the-bacterial kill curve (AUBKC) and log change in viable count at 24 h (Delta24). For daptomycin, dose escalation was used to determine the relationship between ABE and AUC/MIC.

Results
Daptomycin was bactericidal against the MRSA strains. Daptomycin and vancomycin were active against the VRSA strain; teicoplanin had a static effect. The higher inoculum reduced the ABEs. Analysis of variance (ANOVA) indicated that daptomycin had a superior ABE to teicoplanin and vancomycin. Daptomycin fAUC/MIC was related to AUBKC and Delta24; the fAUC/MIC ratios for a static effect and 1 log and 3 log drop were 37.2 +/- 16.5, 40.6 +/- 17.8 and 49.8 +/- 19.2, respectively.

Conclusions
These data define the fAUC/MIC sizes for daptomycin for bacteriostatic and bactericidal ABEs and indicate that a 6 mg/kg dose of daptomycin is superior to vancomycin and teicoplanin against MRSA and VRSA strains.

Antimicrobial Chemotherapy