Recent data from the World Health Organization (WHO) finds that an astounding one in six lab-confirmed human bacterial infections are resistant to antibiotics. Antimicrobial resistance (AMR) poses a significant global threat. One of the ways that AMR can be mitigated is by using antimicrobial susceptibility testing (AST) to determine a more suitable antibiotic for the isolate you are working with.
AST is the in vitro measure of a pathogen’s response to an antimicrobial agent to be able to predict therapeutic efficacy. An in vitro study refers to a controlled environment such as a test tube or petri dish, outside of a living organism. This is distinct from in vivo research that is done with or within a living organism. Studies with animal models or human clinical trials would be examples of in vivo studies. Clinical microbiology labs use AST data to determine which antimicrobial regimen is effective for the pathogen. In fact, the global AST market is projected to reach $3.7B by 2027.
One of the superbugs of global concern is methicillin-resistant Staphylococcus aureus (MRSA). The WHO has listed MRSA as a “priority pathogen” due to its successful clones and ability to spread life-threatening diseases. It’s resistant to many antibiotics such as methicillin, penicillin, oxacillin, cloxacillin, cefazolin, cefoxitin and many others. Rapid identification, culture and subsequent susceptibility testing is needed to mitigate the risk from MRSA since it persistently evolves with a constant emergence of new genetically variant strains. Popular antimicrobials for in vitro MRSA research include Ceftaroline, Daptomycin, Teicoplanin, Telavancin and Vancomycin.
MRSA strains can produce a penicillin-binding protein (PBP) with a diminished affinity for most semisynthetic penicillins. The PBP can be encoded by an obtained gene, mecA. This gene is carried on a mobile genetic element (MGE) selected staphyloccal cassette chromosome mec (SCCmec). Emergence of methicillin-resistant strains is due to the bacteria acquiring the mobile genetic elements which therefore make them resistant to methicillin. PCR-based assays are designed to detect the presence of resistance genes like mecA , but it is challenging because only a few resistance genes are firmly associated with phenotypic resistance.
Other strategies for MRSA are being explored such as multi-compound strategies, synthetics, and natural compounds to combat this global threat.
If you are investigating a certain strain of MRSA or another bacterial strain for that matter, our Antimicrobial Index has MIC information on over 7,000 unique strains, and 4,000 different antimicrobial agents to explore.
Our services for AST is another good place to look if you need to further customize your antimicrobial of interest to make it better suited to your specifications and AST system.
Our dedicated blog series on AST is another way to learn more about this technology if you are interested in learning more about this topic.
Reference
Nandhini P et al (2022) Recent developments in Methicillin-Resistant Staphylococcus aureus (MRSA) treatment: A review. Antibiotics. 2022 11(5):606 Link