Methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA), an organism resistant to many drugs, is seen with increasing frequency in hospitals and long-term care facilities. It can cause life-threatening disease, and treatment options are limited. MRSA infections are indeed associated with a 40% mortality when found in the blood of patients suffering from severe staphylococcal infection. According to the World Health Organization (WHO), resistance of Staphylococcus aureus (Staph A) to methicillin, its usual antibiotic, increased from 2% in 1975 to 60% today and no new antibiotic is expected on the market before at many years. Whereas MRSA is considered as a nosocomial pathogen, recent reports showed an increasing number of outbreaks in the community, despite the absence of known risk factors (prior hospitalization, antibiotic use or household contacts from the healthcare system). Such atypical MRSA is known to produce a potent toxin causing severe skin infections and necrotising pneumonia in both immunocompromised and immunocompetent individuals.

Detection and therapeutic strategies

With such critical health issues, an early detection of MRSA carriers is crucial for infection control strategies. Strategies to fight MRSA transmission are indeed well-described, and can efficiently reduce subsequent colonization and infection. However, these strategies need to be focused on patients with confirmed MRSA and defined resistance phenotype.

Molecular methods (nucleic acids based assays) are emerging diagnostics tools for rapid detection of a specific gene or DNA sequences that are indicators of the presence of bacteria. However, the molecular tests in general, such as multiplex PCR, DNA sequencing, and microarrays, are still very manual, lengthy and complex, and necessitate large laboratory resources which prevent their broad use. To overcome these limitations, the whole process of molecular tests must be revised and simplified. Miniaturization and automation present a great potential for the integration of the molecular assays in an easy-to-use and flexible device, as well as for its acceleration.