Infectious Disease Compendium

Piperacillin/Tazobactam (Zosyn®)


CrCl Formula

CrCl > 80: 2.5 - 4.5 iv q 6 - 8 h. Probably best to dose q 8 with a 4 hour infusion. It decreases mortality (PubMed).

CrCl 80-50: 2.5 - 4.5 iv q 6 - 8 h.

CrCl 50-10: ?

CrCl < 10: ?


Peritoneal dialysis:

Obesity dosing

Important side effects

Important drug interactions

Methotrexate, probenecid, vecuronium.

When added to vancomycin it is associated with acute kidney injury (PubMed) (PubMed). One article is entitled (PubMed) "Increasing Evidence of the Nephrotoxicity of Piperacillin/Tazobactam and Vancomycin Combination Therapy—What Is the Clinician to Do?" How about not give that combination? Duh. How hards can it be to, oh, I don't know, think about the disease and give something else? Hard it appears.

A meta-analysis suggests an odds ratio of 3 for AKI (PubMed) when combined with vancomycin.

Rants and Screeds

Use of this antibiotic in sepsis empirically is associated with increased mortality rates compared to other agents, especially if the MIC is in the high end of 'sensitive', greater than 2 ug/ml.

Funny how we had a piperacillin shortage (inexpensive) but plenty of pip/tazo (expensive). Wonder why?


Beta-lactamse inhibitor combinations are problematic with some gram negative rods, depending on the strain and the type of beta-lactamase. Clavulanate can be antagonistic for ticarcillin (PubMed) and other beta lactam antibiotics (PubMed). This is less of a problem with tazobactam, maybe occurring 1% of the time (PubMed).

Treatment of choice

In my opinion? Nothing. I do not believe I have ever used the drug.

Use for

Like all beta lactamase inhibitor combination, I can't find a use for them. It is approved for appendicitis, cellulitis, cutaneous abscesses, diabetic foot infection, diverticulosis/itis, endometritis, Escherichia coli infections, gynecologic infections, intra abdominal infections, neutropenic fever, PID, peritonitis, pneumonia.

Don't use for



Curious Cases

Relevant links to my Medscape blog

Beta-lactam Side Effect - Sometimes an STD

Grumpy and Getting Worse with Age