# Penicillin-Binding Proteins in Streptococcus agalactiae and Their Association with Reduced Penicillin Susceptibility: An Overview

## TL;DR

This paper reviews how penicillin-binding proteins in Streptococcus agalactiae are linked to reduced penicillin susceptibility, a growing global health concern.

## Contribution

The paper compiles and highlights recent findings on penicillin resistance in S. agalactiae, emphasizing the role of PBP2X proteins.

## Key findings

- Reduced penicillin susceptibility in S. agalactiae is increasingly reported in Japan, the U.S., Canada, and Africa.
- PBP2X is a key penicillin-binding protein associated with β-lactam resistance in streptococci.
- High levels of penicillin resistance in invasive S. agalactiae strains are a cause for concern.

## Abstract

Streptococcus agalactiae are bacteria that can cause a range of infections, some of them life-threatening. Currently, antimicrobial resistance has become a global problem that puts public health at risk. Despite the widespread use of β-lactams, penicillin remains the first-line antimicrobial for the treatment of invasive S. agalactiae infections. However, reduced susceptibility and resistance to penicillin have been identified in several countries. Penicillin-binding proteins, mainly PBP2X, have been associated with reduced susceptibility to β-lactams in streptococci. The aim of this review is to summarize currently published data on penicillin-binding proteins in S. agalactiae and penicillin susceptibility, highlighting the increasing number of strains with reduced susceptibility and resistance to penicillin commonly used in the prophylaxis and treatment of invasive infections by this pathogen. Data on invasive S. agalactiae strains with high levels of penicillin resistance have been found in Japan, the United States, Canada, and Africa. The data on antibiotic resistance are alarming and require increased monitoring of strains with reduced penicillin susceptibility, as well as preventive control measures to avoid the spread of resistant mutant strains.