Since the infection is getting worse, it is clear that the treatment with cefope
ID: 190640 • Letter: S
Question
Since the infection is getting worse, it is clear that the treatment with cefoperazone is not working. Also, at this time, the results come back from the antibiotic-resistance tests on the P. aeruginosa isolate from the patient. It has been determined that this isolate is partially resistant to most of the cephalosporin derivatives tested AND is non-susceptible to the carbapenem antibiotic doripenem. This means that the antibiotic treatment was inappropriate. Initial inappropriate antibiotic therapy is associated with very bad outcomes for multi-drug resistant P. aeruginosa. The prognosis is very poor. The patient is put in isolation and the infection route is traced to the catheter.
There is controversy about the best options for treatment of multi-drug resistant Pseudomonas. But, in this case an emergency decision is made to treat the patient with the combination of tigecycline and colistin, which some reports indicate act synergistically against multi-drug resistant Pseudomonas. Tigecycline is a glycylcycline antibiotic. It is related to tetracyclines, but is often effective against tetracycline-resistant bacteria. Colistin is a polymyxin antibiotic.
8) With what general bacterial process do tetracycline antibiotics interfere?
9) With what general bacterial process do polymyxin antibiotics interfere?
10) Why are polymyxin antibiotics only used as an intravenous or ingested treatment as a last resort?
Explanation / Answer
8) Tetracycline antibiotic inhibit protein synthesis by preventong the attachment of aminoacyl -tRNA to the Acceptor site (A site) in Ribosome.
9) Polymixin antibiotic is effective against the gram negative bacteria. It disrupts the outer membrane and inner membrane by binding with the Lipopolysaccharide (LPS).
10) Polymixin antibiotic are relatively neurotoxic and nephrotoxic so are used only as a last resort if modern antibiotoc fails.