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Updated: Aug 16, 2025
Subcutaneous Infection of Methicillin Resistant Staphylococcus Aureus MRSA
Published on: February 9, 2011
[Comparison of PVL-producing MRSA Showing POT Type 106-77-113 and POT Type 106-255-121 Detected in Materials Derived
Hitoshi Miyamoto1, Shinobu Murakami1, Minami Tamaki2
1Department of Clinical Laboratory, Ehime University Hospital. Department of Infection Control Team, Ehime University Hospital.
Abstract:
Methicillin-resistant Staphylococcus aureus (MRSA) strains showing POT type 106-77-113 have been associated with USA300. Additionally, many strains produce Panton-Valentine Leukocidin (PVL). Until 2018, 106-77-113 was the most dominant POT-type PVL-producing bacteria isolated in our hospital; however, in 2018, one strain with POT type 106-255-121 was isolated, and thereafter, since 2019, an increasing trend towards isolation of this strain has been observed. In this study, we compared two PVL-producing strains detected in skin infections-derived materials from outpatients during the three-year period between 2019 and 2021 through genetic analysis using next-generation sequencers. Eight, each of POT types 106-77-113 (POT-A) and 106-255-121 (POT-B), strains were included in this study, and PVL productivity, drug susceptibility, multi-locus sequencing typing (MLST), and resistance genes and virulence genes were detected. Both the groups shared the same MLST profile (3-3-1-1-4-4-3), but a single nucleotide mutation of ARCC was detected in POT-B type strain, which was determined to be similar to ST 8 of POT-A and POT-B type strains. Only POT-B type strains harbored aac(6')-aph(2″) and erm(A) genes, consistent with the results of drug susceptibility tests. All the strains were resistant to GM and CAM and were positive to D-zone test. On the other hand, the POT-A strains were sensitive to GM, and 7 of 8 strains were sensitive to CLDM and MINO. However, one POT-A type strain was found to harbor erm(C), tet(K), and tet(M) genes and was resistant to CAM, CLDM, and MINO. Both groups of isolates harbored 17 genes including ACME, lukF-PV, and LukS-PV, and no difference in pathogenicity was observed. In our hospital, one strain of POT type 106-255-121 was isolated for the first time in 2018, and the number of isolates of this type has been increasing since then. The present study confirms that POT type 106-255-121 strains have the same virulence as POT type 106-77-113 strains have and have also acquired a drug resistance gene.
Insights
A new Methicillin-resistant Staphylococcus aureus (MRSA) strain, POT type 106-255-121, shows similar virulence to the dominant POT type 106-77-113. This emerging strain has acquired drug resistance genes, posing a growing concern in clinical settings.
Area of Science:
- Clinical Microbiology
- Molecular Epidemiology
- Antimicrobial Resistance
Background:
- Methicillin-resistant Staphylococcus aureus (MRSA) strains, particularly those producing Panton-Valentine Leukocidin (PVL), are significant pathogens.
- The POT type 106-77-113 MRSA strain was historically dominant, but a new strain, POT type 106-255-121, has emerged and increased since 2018.
- Understanding the genetic and phenotypic differences between these strains is crucial for infection control.
Purpose of the Study:
- To genetically compare PVL-producing MRSA strains of POT type 106-77-113 (POT-A) and 106-255-121 (POT-B) isolated from skin infections.
- To analyze differences in virulence factors, drug susceptibility, and resistance genes between the two POT types.
Main Methods:
- Next-generation sequencing was employed for genetic analysis of eight strains each of POT-A and POT-B.
- Key analyses included Panton-Valentine Leukocidin (PVL) productivity, drug susceptibility testing, multi-locus sequencing typing (MLST), and detection of resistance and virulence genes.
- Specific genes such as ACME, lukF-PV, LukS-PV, aac(6')-aph(2″), erm(A), erm(C), tet(K), and tet(M) were investigated.
Main Results:
- Both POT-A and POT-B strains shared the same MLST profile (ST 8), but POT-B strains exhibited a single nucleotide mutation in ARCC.
- POT-B strains exclusively harbored aac(6')-aph(2″) and erm(A) genes, correlating with resistance to gentamicin (GM) and clindamycin (CLDM).
- While POT-A strains were generally sensitive to GM, CLDM, and minocycline (MINO), one strain possessed erm(C), tet(K), and tet(M) genes, conferring resistance to CAM, CLDM, and MINO. Both groups showed similar pathogenicity profiles.
Conclusions:
- The emerging POT type 106-255-121 MRSA strain demonstrates comparable virulence to the previously dominant POT type 106-77-113 strain.
- POT type 106-255-121 strains have acquired specific drug resistance genes, contributing to their increasing prevalence.
- Continuous surveillance of MRSA strains is essential to monitor the emergence of new resistance patterns and virulence characteristics.
