Pneumococcal resistance to penicillin G is mainly acquired by :
**Core Concept**
Pneumococcal resistance to penicillin G is a significant concern in the treatment of pneumococcal infections. This resistance is primarily acquired through genetic mutations that alter the penicillin-binding proteins (PBPs) in the bacterial cell wall.
**Why the Correct Answer is Right**
Pneumococcal resistance to penicillin G is mainly acquired through the acquisition of genetic mutations that alter the penicillin-binding proteins (PBPs). Specifically, the mecA gene, which encodes for a modified PBP2a, is responsible for this resistance. This gene is usually acquired through horizontal gene transfer from other bacteria, such as Staphylococcus aureus. The mecA gene allows the pneumococcus to produce a PBP2a that is resistant to beta-lactam antibiotics like penicillin G.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because pneumococcal resistance to penicillin G is not primarily acquired through the production of beta-lactamase enzymes. While some pneumococci may produce beta-lactamases, this is not the main mechanism of resistance to penicillin G.
**Option B:** This option is incorrect because pneumococcal resistance to penicillin G is not primarily acquired through the acquisition of plasmids. While plasmids can carry resistance genes, the mecA gene is usually located on a pathogenicity island within the pneumococcal chromosome.
**Option C:** This option is incorrect because pneumococcal resistance to penicillin G is not primarily acquired through the use of efflux pumps. Efflux pumps can contribute to resistance, but they are not the main mechanism of resistance to penicillin G.
**Clinical Pearl / High-Yield Fact**
The mecA gene is a significant concern in the treatment of pneumococcal infections, and its presence can make penicillin G ineffective. It is essential to perform susceptibility testing to determine the optimal antibiotic therapy for pneumococcal infections.
**Correct Answer:** C. acquisition of the mecA gene.