Plasmid composition of Staphylococcus species

Area of Science:

• Microbiology
• Molecular Biology
• Bacteriology

Background:

• Staphylococci are a diverse group of bacteria with varying genetic elements.
• Plasmids, extrachromosomal DNA, play a significant role in bacterial adaptation and evolution.
• Understanding plasmid composition is crucial for bacterial taxonomy and epidemiology.

Purpose of the Study:

• To investigate and compare the plasmid composition across 13 recognized staphylococcal species.
• To identify potential correlations between plasmid profiles and specific staphylococcal species or biotypes.
• To assess the utility of plasmid patterns as a taxonomic marker in staphylococci.

Main Methods:

• Screening of 342 staphylococcal isolates from 13 species.
• Agarose gel electrophoresis was employed to analyze plasmid DNA.
• Molecular weights of plasmids were estimated.

Main Results:

• Large plasmids (≥30 x 10^6 MW) were uncommon across all staphylococcal species studied.
• Moderately large plasmids (15-29 x 10^6 MW) were prevalent in Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus saprophyticus groups, but rare in S. sciuri, S. intermedius, S. hyicus, and S. simulans.
• Small plasmids were frequently observed in most staphylococcal species.
• More complex plasmid profiles were noted in simian subspecies/biotypes compared to human ones for species like S. warneri, S. haemolyticus, S. cohnii, S. xylosus, and S. aureus.

Conclusions:

• Plasmid distribution varies significantly among staphylococcal species.
• While some species exhibit distinct plasmid patterns, these are not currently reliable taxonomic markers due to strain variability and potential plasmid transfer.
• Further research is needed to fully elucidate the role of plasmids in staphylococcal diversity and evolution.