**Core Concept**
Pseudomonas infections are challenging to treat due to their inherent resistance to many antibiotics. The choice of antibiotic depends on the susceptibility pattern of the isolate and the severity of the infection. In general, antibiotics effective against Pseudomonas aeruginosa include carbapenems, fluoroquinolones, aminoglycosides, and polymyxins.

**Why the Correct Answer is Right**
Pseudomonas aeruginosa is often resistant to cephalosporins, penicillins, and many other antibiotics due to the production of beta-lactamases. However, certain antibiotics like meropenem, imipenem, and doripenem are effective against Pseudomonas due to their stability against beta-lactamases. Other effective antibiotics include ciprofloxacin, gentamicin, and colistin.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because most cephalosporins are not effective against Pseudomonas due to beta-lactamase production.
**Option B:** This option is incorrect because most penicillins are not effective against Pseudomonas due to beta-lactamase production.
**Option C:** This option is incorrect because it is not a commonly used antibiotic against Pseudomonas.

**Clinical Pearl / High-Yield Fact**
It is essential to determine the susceptibility pattern of Pseudomonas isolates before initiating treatment to choose the most effective antibiotic.

**Correct Answer: C.**