You are looking after a 54 year old man post cadaveric liver transplantation with impaired graft function and failure to progress. A large subhepatic bile collection was drained percutaneously on day 7 when he was started on piperacillin-tazobactam. Culture of the drain fluid reveals heavy growth of Enterococcus spp.
Piperacillin activity is similar to penicillin, and less than that of ampicillin. Enterococci are relatively penicillin resistant; E. faecium is more resistant than E. faecalis. Most VRE have high-level resistance to β-lactams (and aminoglycosides).
The main options would be:
c) Main toxicities of each of the antibiotics:
A reasoned answer is required. Linezolid may be preferred over teicoplanin due to its greater efficacy and better tissue penetration (it is poorly protein bound, so volume of distribution approximates to total body water). No dosage reduction is necessary in renal or hepatic failure. Van A resistance is common in Australia, so many VRE are teicoplanin resistant. Tigecycline and daptomycin generally regarded as third line drugs. Ceftaroline new to practice and limited experience to date.
VRE seems to be a topic favoured by the CICM examiners.
This bunch of cocci were previously known as Group D streptococci. They are not particularly pathogenic, but their intrinsic resistance to antibiotics makes them interesting to the intensivist.
a) Enterococci have intrinsic resistance to β-lactam antibiotics due to the low affinity of their penicillin-binding proteins for penicillin. Interestingly, piperacillin has approximately the same activity as benzylpenicillin against these enterococci; ticarcillin and cephalosporins have about four times less activity, and are thus essentially useless.
b) Antibiotic choices and their toxicities
As to this specific biliary sepsis patient? Their collection is VRE infected, and one needs a drug with good tissue penetration. The college have chosen linezolid.
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