**Question:** True statements about Pneumococcus are all except-

A. Pneumococcus is a Gram-positive bacterium
B. Pneumococcus is sensitive to penicillin
C. Pneumococcus can cause meningitis
D. Pneumococcus is resistant to amoxicillin

**Correct Answer:** .

**Core Concept:** Pneumococcus is a gram-positive bacterium belonging to the Streptococcus genus. It is known for causing various infections in humans, such as pneumonia, meningitis, and bloodstream infections. Penicillin is a group of antibiotics that are effective against many Gram-positive bacteria, including Pneumococcus. However, Pneumococcus has developed resistance to penicillin in some strains, making penicillin less effective against them. Amoxicillin is a beta-lactam antibiotic, which includes penicillin and other similar drugs. Resistance to amoxicillin can occur due to beta-lactamase production by the bacteria, rendering the drug ineffective.

**Why the Correct Answer is Right:** Penicillin is effective against Pneumococcus, especially in its susceptible strains. As mentioned, some Pneumococcus strains have developed resistance to penicillin, which is why option B is incorrect. Amoxicillin is also a beta-lactam antibiotic, which could be ineffective against resistant strains due to beta-lactamase production.

**Why Each Wrong Option is Incorrect:**

A. Pneumococcus is classified as a Gram-positive bacterium, so option A is incorrect as it contradicts the core concept of the bacterium's classification.

D. Pneumococcus can develop resistance to amoxicillin due to beta-lactamase production, making option D incorrect for the same reason as option B.

**Clinical Pearls:**

- Understanding antibiotic resistance mechanisms is crucial in clinical practice to guide appropriate treatment choices for patients with suspected bacterial infections.
- Gram staining helps differentiate between Gram-positive and Gram-negative bacteria, which can guide antibiotic choice in some cases.
- The World Health Organization (WHO) has identified antibiotic resistance as a global health threat, emphasizing the importance of rational antibiotic use and appropriate prescribing practices.