Management of healthcare-associated methicillin-resistantStaphylococcus aureus

Mechanisms of β-lactam antimicrobial resistance and epidemiology of major community- and healthcare-associated multidrug-resistant bacteria

Alexander Fleming's discovery of penicillin heralded an age of antibiotic development and healthcare advances that are premised on the ability to prevent and treat bacterial infections both safely and effectively. The resultant evolution of antimicrobial resistant mechanisms and spread of bacteria bearing these genetic determinants of resistance are acknowledged to be one of the major public health challenges globally, and threatens to unravel the gains of the past decades. We describe the major mechanisms of resistance to β-lactam antibiotics - the most widely used and effective antibiotics currently - in both Gram-positive and Gram-negative bacteria, and also briefly detail the existing and emergent pharmacological strategies to overcome such resistance. The global epidemiology of the four major types of bacteria that are responsible for the bulk of antimicrobial-resistant infections in the healthcare setting - methicillin-resistant Staphylococcus aureus, vancomycin-resistant enterococci, Enterobactericeae, and Acinetobacter baumannii - are also briefly described.

Are glycopeptides still appropriate and convenient for empiric use?

The glycopeptides vancomycin and teicoplanin are widely used, and indeed recommended for, the treatment of severe or resistant Gram-positive infections. Therapeutic drug monitoring is widely used for vancomycin but less commonly for teicoplanin, and remains controversial. We report the cost savings of a formulary decision to replace teicoplanin with daptomycin for the empiric treatment of complicated skin and soft tissue infections (CSSTIs), staphylococcal bacteraemia and hospital-acquired Gram-positive sepsis. In the Intensive Therapy Unit (ITU) we optimised treatment of serious Gram-positive infections by substituting teicoplanin with vancomycin administered by continuous infusion. Costs were calculated using British National Formulary (BNF) prices and costs for therapeutic drug monitoring. Daptomycin (350 mg/d) use was associated with a cost saving per 7 days of treatment of 86 pounds and vancomycin with 51 pounds (4 g/d) to 276 pounds (2 g/d) compared to the 600 mg teicoplanin dose. Our own formulary re-positioning of glyco/lipopeptides, i.e. the preferential use of vancomycin in the ITU and substitution of teicoplanin with daptomycin, is cost-effective and provides better therapeutic alternatives. Continuous vancomycin infusion in the ITU setting guarantees optimal dosing for severely ill patients. Daptomycin use on surgical and medical wards, apart from being marginally cheaper than teicoplanin, guarantees optimal dosing without the need for drug monitoring.

Epidemiology and economic impact of meticillin-resistant Staphylococcus aureus: review and analysis of the literature

In the past 2 decades, meticillin-resistant Staphylococcus aureus (MRSA) has become an increasingly prevalent problem in healthcare, both in acute care institutions and in the community. MRSA is associated with worse outcomes and higher costs for care than meticillin sensitive S. aureus (MSSA). MRSA is a particular problem in several conditions, including hospital-acquired pneumonia (including ventilator-associated pneumonia), skin and soft tissue infections, and diabetic foot infections. Hospitalisation costs associated with MRSA infection are substantially greater than those associated with MSSA infection, and MRSA has wider economic effects that involve indirect costs to the patient and to society. In several countries, infection control programmes have shown potential economic benefits, as savings accruing from strict and effective control have been shown to outweigh the cost of policy implementation. Standard therapy is based on glycopeptide treatment, usually with vancomycin, although resistance to this agent has emerged. Alternative available treatments for MRSA include teicoplanin, tigecycline, daptomycin, quinupristin-dalfopristin and the oxazolidinone, linezolid, which has a higher acquisition cost than vancomycin but is available as intravenous and oral formulations. Despite some limitations of analyses to date, linezolid has been shown to be cost effective in the treatment of MRSA and appears to be related, in part, to the drug's potential for facilitating earlier discharge from hospital. Current opinion favours rational prescribing to maximise therapeutic benefit and minimise the risk of further antibacterial resistance.