A patient has a lung infection with Pseudomonas aeruginosa. What antibiotic should be used against it?

Pseudomonas aeruginosa is a common bacterium that can cause lung infections, particularly in people with weakened immune systems or with lung diseases like cystic fibrosis. It is known for its resistance to many antibiotics, but there are still several options that can be used to treat infections caused by this bacterium.

1. Aminoglycosides: This class of antibiotics, which includes drugs like gentamicin and tobramycin, is often effective against Pseudomonas aeruginosa. They work by binding to the bacteria's ribosomes, preventing them from making proteins and thus inhibiting their growth.

2. Fluoroquinolones: These antibiotics, such as ciprofloxacin and levofloxacin, are also commonly used to treat Pseudomonas aeruginosa infections. They work by inhibiting the bacteria's DNA gyrase, an enzyme necessary for DNA replication.

3. Carbapenems: This class of antibiotics, which includes drugs like imipenem and meropenem, can also be effective against Pseudomonas aeruginosa. They work by inhibiting the bacteria's cell wall synthesis, causing the bacteria to lyse, or burst.

4. Piperacillin/tazobactam: This combination drug is a type of penicillin that is often used to treat Pseudomonas aeruginosa infections. It works by inhibiting the bacteria's cell wall synthesis.

5. Ceftazidime and Cefepime: These are third and fourth generation cephalosporins respectively, that are used to treat Pseudomonas aeruginosa infections. They also work by inhibiting the bacteria's cell wall synthesis.

It's important to note that the choice of antibiotic should be guided by the results of a susceptibility test, as Pseudomonas aeruginosa can be resistant to many antibiotics. The patient's overall health and the severity of the infection should also be taken into account. Always consult with a healthcare provider for appropriate treatment options.