Genetic resistance elements carrying mef subclasses other than mef(A) in Streptococcus pyogenes

Area of Science:

• Microbiology
• Genetics
• Molecular Biology

Background:

• Efflux-mediated erythromycin resistance in Streptococcus pyogenes is primarily linked to the mef gene, predominantly mef(A).
• However, some strains harbor different mef subclasses, necessitating further investigation into their associated genetic elements.

Purpose of the Study:

• To characterize composite genetic elements containing mef subclasses other than mef(A) in S. pyogenes.
• To identify other resistance genes associated with these mef-containing elements.

Main Methods:

• Polymerase chain reaction (PCR) mapping was employed to determine the genetic elements.
• Analysis of mef subclasses, including mef(A/E), mef(E), mef(I), and a novel mef gene.

Main Results:

• Mosaic mef(A/E) elements associated with tet(O) were found within a Φm46.1-like element.
• mef(E) was found in mega elements and the composite element Tn2009, associated with tet(M).
• mef(I) and catQ were linked in a defective IQ element, and a novel mef variant was associated with catQ and tet(M) in a 5216IQ-like complex.

Conclusions:

• Composite genetic elements harboring mef subclasses are shared between Streptococcus pyogenes and Streptococcus pneumoniae.
• Distinguishing mef subclasses based on their containing genetic elements is important for understanding antibiotic resistance mechanisms.