Wednesday, August 13, 2008

The role of carbapenems in serious infections

In the treatment of sepsis an adequate antibiotic spectrum for the initiation of therapy (“empiric”) is essential. Patients fare worse if the coverage has to be broadened after the return of culture results. The emerging resistance of gram negative bacteria makes adequate empiric therapy more challenging. In particular, the appearance of extended spectrum beta lactamases makes late generation cephalosporins less attractive in many settings. This suggests an increasing role for carbapenems. A review in Critical Care examines this role. A future concern is the emergence of more resistance to carbapenems. What will we do when they begin to wear out their welcome? There’s not much else to turn to and the dry antibiotic development pipeline limits future prospects. (And you think hospitals are unsafe now!).

To illustrate what a challenge treatment of serious gram negative infections is in some centers, read this from the review:

At New York Hospital Queens, KPC-producing Klebsiella have become endemic. Thus, neutropenic patients with serious hospital-acquired infection receive a five-drug regimen to treat a wide variety of potential multiresistant pathogens. This consists of polymyxin B, vancomycin, rifampin, tigecycline, and a carbapenem.


#1 Dinosaur said...

I have an issue/question that is completely semantic: the ubiquitous word choice used in discussing antibiotic coverage before and after identification of the offending organism(s).

"Broad"/"empiric" coverage is required to treat all the likely pathogens in a particular clinical scenario prior to the availability of definitive information about the causative organism(s). Once you have culture and sensitivity results back, aren't any drug changes by definition done to better target the identified pathogen(s) (ie, "narrow" the "coverage")? Therefore from a strictly semantic viewpoint, it makes no sense to talk about "broaden[ing] coverage after the return of culture results." Certainly I understand the idea of patients faring worse if appropriate antibiotics were delayed because the initial "empiric" selection of drugs did not adequately treat whatever the offending pathogen turned out to be.

(I may have to explore this at greater length on my own blog. It's not a medical issue at all; rather a discussion about the way language is used in the field of infectious disease.)

R. W. Donnell said...

The misuse you cite may not be all that ubiquitous as much as it is my own poor choice of words. I should have said *escalate*, meaning "to use a bigger gun."

A more ubiquitous misuse of words, not confined to ID types, may be the word "empiric" in reference to initial treatment based on the clinician's best hunch pending more definitive diagnosis. "Empiric" really means evidence based and could be applicable to treatment directed against a known pathogen.