Molecular Significance of Methicillin-Resistant Staphylococcus aureus on Antibiotic Resistance Profi

Staphylococcus aureus is a gram positive, aerobic bacterium that is observed in the epidermal layer of the skin, nose and throat of many humans and animals. This bacterial pathogen does not affect the host if carried externally; however, when an immunocompromised host encounters S. aureus through open wounds, the bacterium can cause a range of minor to severe symptoms. In 1940 during World War II, Alexander Fleming was experimenting with the penicillin antibiotic that he derived from fungi, and its effects on S. aureus. During World War I, pneumonia had a high mortality rate that claimed thousands of soldiers' lives due to bacterial infection. With Fleming producing mass quantities of penicillin, and distributing them to infected patients the mortality rate significantly decreased. Later in the same year, an isolate of Escherichia coli was examined, and it was found to have contained a β-lactam ring enzyme capable of hydrolyzing penicillin (penicillinase).
The first discovery of S. aureus to have contained the penicillinase enzyme occurred in 1944, and in only 4 years the first outbreak of penicillin-resistant S. aureus took place in a United Kingdom hospital. The authors of the article found it important to reveal that different strains of CA-MRSA exist. In Shanghai, the most common strain of MRSA contains the molecular profile ST59-MRSA-IV and ST59-MRSA-V. These two strains showed complete resistance to the antibiotics clindamycin, erythromycin, and tetracycline while other strains expressed different profiles.<ref name=":1" />
To conduct the experiment, researchers collected 80 isolates from children admitted for the first time at Shanghai Children’s medical center. Within 48 hours of hospitalization, samples were taken to avoid any contamination from hospital equipment reducing the probability of tainting the experiment examining CA-MRSA not HA-MRSA.<ref name=":1" /> Normal biochemical testing was performed to determine the presence of S. aureus. The experiment further used MLST analysis, SCCmec and Spa typing to examine molecular patterns between isolates. Figure 2 of the article illustrates how different molecular typing has its own unique antibiotic resistance profiles which serves as an important reference for healthcare professionals to consider when treating infected patients.<ref name=":1" /> Researchers, and other medical professionals have concluded that a simple yet effective technique to combat different strains of MRSA could be as simple as rotational antibiotic use.

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