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Detection of methicillin-resistant Staphylococcus aureus using phage amplification combined with matrix-assisted laser desorption/ionization mass spectrometry
Jon C. Rees, John R. Barr
Anal. Bioanal. Chem. (2017) 409: 1379
The US Centers for Disease Control and Prevention recently reported on the threats posed by antibiotic resistant bacteria. They estimated that each year in the USA, 2 million people become infected and at least 23,000 people die from resistant bacteria, at a healthcare cost of $20 billion. They also stated that this is a worldwide problem.
To enable faster detection of these resistant strains, the authors have developed a method where samples with S. aureus are incubated together with bacteriophage. They are then rapidly digested with trypsin and analyzed by MALDI-TOF MS. The method detects tryptic peptides from amplified phage capsid proteins, and has more sensitivity than methods that have tried to detect the intact phage proteins.
Antibiotic resistance is determined by the detection of phage replication in the presence of an antibiotic, when compared to a no-antibiotic control. After treating four S. aureus strains with cefoxitin, significant phage amplification in both the no-antibiotic and the cefoxitin-containing samples was shown on the resistant strains, while the susceptible strains showed no amplification upon cefoxin treatment.
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