Potential role of host defense antimicrobial peptide resistance in increased virulence of health care-associated MRSA strains of sequence type (ST) 5 versus livestock-associated and community-associated MRSA strains of ST72.
Kang. Kyoung-Mi KM; Park. Jong-Hwan JH; Kim. So Hyun SH; Yang. Soo-Jin SJ
Key Findings
- Hospital‑associated MRSA (ST5) shows higher resistance to LL‑37, BMAP‑28, and polymyxin B than community‑associated MRSA (ST72).
- The increased resistance is associated with a more positively charged bacterial surface.
- Both strains have similar hemolysis, gelatinase activity, and superantigen gene profiles, but ST5 can suppress early cytokine responses in murine macrophages.
Practical Outcomes
- For biohackers, this research mainly highlights that some bacterial infections can evade natural antimicrobial peptides, suggesting that simply boosting LL‑37 levels may not be sufficient against certain resistant strains. It does not provide new protocols, dosages, or direct health‑optimizing actions.
Summary
The study compared two types of MRSA bacteria in Korea and found that the hospital‑associated strain (ST5) is better at resisting the body's natural antimicrobial peptide LL‑37 (and similar peptides) than the community‑associated strain (ST72). This resistance is linked to a more positive surface charge on the bacteria, and the hospital strain can also dampen early immune signals in mouse cells.
Abstract
The most significant community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) in Korea is sequence type (ST) 72 with staphylococcal cassette chromosome mec (SCCmec) type IV (ST72-MRSA-IV). Although the impact of CA-MRSA on the clinical outcomes versus healthcare-associated (HA)-MRSA remains unclear, it has recently been revealed that ST5 HA-MRSA-II is associated with higher mortality compared with ST72 CA-MRSA-IV, suggesting higher virulence in ST5 HA-MRSA-II strains. In this investigation, human-/animal-originated ST72-MRSA-IV strains were examined for virulence phenotypes and compared with those of ST5-MRSA-II strains, the established HA-MRSA in Korea. Overall, ST5 HA-MRSA-II strains demonstrated higher levels of resistance to host defense-cationic antimicrobial peptides of human (LL-37), bovine (BMAP-28), and bacterial (polymyxin B) origins versus ST72-MRSA-IV strains via enhanced surface positive charge. Hemolysis profiles, gelatinase activity, and staphylococcal superantigen gene profiles were not different between ST72 CA-MRSA and ST5 HA-MRSA strains. However, ST5 HA-MRSA strains were able to downregulate initial cytokine response in murine macrophages.
Study Information
pubmed
2018
2018-11-30T00:00:00.000Z
10.1016/j.cimid.2018.11.012
14
42