Friday, March 15, 2013

15 March 2013 “We has met the enemy and he is us”
Overview of the Epidemiological Profileand Laboratory Detection of Extended-Spectrum β-Lactamases
1.      Michael A. Pfaller1 and 
2.      John Segreti2
+Author Affiliations
1.      1Department of Pathology, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City
2.      2Department of Medicine, Rush Medical College of Rush University, Chicago, Illinois
1.      Reprints or correspondence: Dr. Michael A. Pfaller, University of Iowa, 200 Hawkins Dr., Dept. of Pathology C606B GH, Iowa City, IA 52242 (
Extended-spectrum β-lactamases (ESBLs) are plasmid-mediated bacterial enzymes that are able to hydrolyze a wide variety of penicillins and cephalosporins. Most ESBLs have evolved by genetic mutation from native β-lactamases, particularly TEM-1, TEM-2, and SHV-1. These parent enzymes are commonly found in gram-negative bacteria, particularly Enterobacteriaceae [1]; they are highly active against penicillins and modestly active against early-generation cephalosporins [2]. The genetic mutations that give rise to ESBLs broaden the parental resistance pattern to a phenotype that includes resistance to third-generation cephalosporins (e.g., cefotaxime and ceftazidime) and monobactams (e.g., aztreonam) [3]. In general, ESBL-producing isolates remain susceptible to cephamycins (e.g., cefoxitin) and carbapenems [3]. Nevertheless, their resistance to a wide variety of common antimicrobials has made the proliferation of ESBL-producing strains a serious global health concern that has complicated treatment strategies for a growing number of patients. In this context, routine screening for ESBL-producing organisms is of great importance. Unfortunately, the overall adherence to routine screening among diagnostic microbiology laboratories is relatively low. Efforts are now under way to improve this situation…”
Cassi Creek:  Walt Kelly’s Pogo is remembered for today’s title line,
          The editorial cartoon and the excerpted and credited journal entry both spotlight the growing difficulty in treating bacterial infections.  The over usage of antibiotics in animal feed mixes is a major culprit.  So is the over prescription of antibiotics by physicians.  The major problem, the reason for the highly technical excerpt, is the pressure placed on physicians to utilize newer, more powerful, and more expensive antibiotics when older, cheaper drugs would suffice. 
          I used to be able to tell which drug reps had been marketing the local doctors by the number of requests for susceptibility testing of bacterial isolates against a or recently released antibiotic.  Pointing out that we provided class representatives rather than brand names never satisfied them.  They had the pen, notepad, coffee mug, in their hand and that was the brand they recalled first. 
          The most damning factor was the knowledge that while most of the 3rd gen cephalosporins had already been implicated in the development of multiple-drug resistance by plasmid-mediated transfer; this information was never pointed out by sales people.  The College of American Pathologists reported the danger in the mid 1980’s but little was done beyond that. 
          The development of superbugs is a very real danger.  There are no new antibiotics nearing production.  There are more and more multiple-resistant bacteria showing up in all communities and in all health care facilities.  Strict application of Infection control practices and severely limiting inpatient stays may be the only weapons left within a decade. 
“It’s all too clear we are on our own!”
Happy Birthday , Shea Rutstein, Park Overall, & Phil Lesh!

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