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Published on: December 7, 2021
Characterization of New Staphylococcus haemolyticus ST42 Populations in Northern Taiwan
Lee-Chung Lin1, Tsui-Ping Liu1, Shih-Cheng Chang2
1Department of Laboratory Medicine, Chang Gung Memorial Hospital, Linkou, Taoyuan, Taiwan.
Abstract:
Staphylococcus haemolyticus is an acquired opportunistic pathogen causing nosocomial infections. Our previous studies of S. haemolyticus showed a group of isolates that produced a significantly higher disease severity than the others. Further molecular typing showed that the sequence type (ST) 42 was the major clone among the isolates. The main aim of this study was to characterize ST42. Sixty-one and 36 isolates were collected from burn and nonburn patients, respectively. Molecular typing, antibiotic susceptibility assays, and phenotypic characterizations were performed. Thirteen STs, including seven new STs, were established (ST42 to ST48). ST42 was prevalent in burn and nonburn patients, and all the pulsotype C isolates were ST42. Four of the novel STs originated from ST3, suggesting that these clonal lineages evolved locally. ST3 and ST42 showed a significant difference in clindamycin susceptibility; molecular typing showed only one MLST locus variation among seven loci in SH1431, which has been reportedly involved in the regulation of biofilm formation through Zn 2+ binding affinities. Seven novel S. haemolyticus STs were identified; phylogenetic analysis suggested the presence of locally evolved clonal lineages. The predominant ST42 showed weak biofilm formation abilities; other factors that cause the clonal lineage change still need further investigation.
Insights
Staphylococcus haemolyticus sequence type 42 (ST42) is a prevalent clone in hospital infections. This study characterized ST42, revealing weak biofilm formation and potential local evolution, necessitating further investigation into its virulence factors.
Area of Science:
- Clinical Microbiology
- Molecular Epidemiology
- Bacterial Pathogenesis
Background:
- Staphylococcus haemolyticus is a significant opportunistic pathogen responsible for nosocomial infections.
- Previous research identified specific S. haemolyticus isolates exhibiting higher disease severity, with sequence type (ST) 42 identified as a predominant clone.
Purpose of the Study:
- To comprehensively characterize the prevalent ST42 clone of Staphylococcus haemolyticus.
- To investigate the molecular and phenotypic differences between ST42 and other S. haemolyticus sequence types.
Main Methods:
- Collection of S. haemolyticus isolates from burn (n=61) and non-burn (n=36) patients.
- Multi-locus sequence typing (MLST) for sequence type (ST) determination and phylogenetic analysis.
- Antibiotic susceptibility testing and phenotypic characterization, including biofilm formation assays.
Main Results:
- Identification of thirteen STs, including seven novel STs (ST42-ST48).
- ST42 was found to be prevalent in both burn and non-burn patient isolates and was associated with pulsotype C.
- Significant differences in clindamycin susceptibility were observed between ST3 and ST42; ST42 exhibited weak biofilm formation capabilities.
Conclusions:
- Seven novel S. haemolyticus STs were identified, with phylogenetic analysis suggesting local evolution of clonal lineages.
- The predominant ST42 clone demonstrates reduced biofilm formation, indicating that other factors likely contribute to its clonal lineage success.
- Further research is required to elucidate the mechanisms driving clonal lineage changes and virulence in S. haemolyticus.
