Detection of Low Affinity Penicillin-Binding Protein Variants in Streptococcus pneumoniae

Area of Science:

• Microbiology
• Biochemistry
• Molecular Biology

Background:

• Penicillin-resistance in Streptococcus pneumoniae is a growing public health concern.
• This resistance is primarily mediated by alterations in penicillin-binding proteins (PBPs), the drug's target enzymes.
• PBPs normally interact with beta-lactam antibiotics, forming an active penicilloyl-PBP complex.

Purpose of the Study:

• To present PBP profile analysis as a method for characterizing beta-lactam resistant Streptococcus pneumoniae strains.
• To establish a technique for visualizing and differentiating strains based on PBP variations.

Main Methods:

• Utilizing radioactive beta-lactam to label PBPs in cells, cell lysates, or membrane fractions.
• Employing SDS-polyacrylamide gel electrophoresis (PAGE) and fluorography to visualize the penicilloyl-PBP complex.
• Analyzing the resulting PBP profiles to detect variations across six key proteins.

Main Results:

• The penicilloyl-PBP complex, formed via an active site serine, is enzymatically inactive and stable.
• PBP profile analysis enables simultaneous detection of variations in six different PBP proteins.
• Each unique PBP profile acts as a molecular fingerprint for a given strain.

Conclusions:

• PBP profile analysis is an effective technique for describing and differentiating beta-lactam resistant Streptococcus pneumoniae isolates.
• This method facilitates the classification of hundreds of isolates into distinct clonal groups based on their PBP fingerprints.
• The technique addresses the need for robust methods to track the increasing frequency of beta-lactam resistant bacterial strains.