A patient in the ICU having fever since 1 week. He empirically started on a ceftriaxone AND amikacin.
the pus sent for culture after 48 hours blood culture report showed klebsiella with ESBL, what is the next step –
Ans. is ‘c’ i.e., Change ceftriaxone to Imipenem [Ref: Harrison I S/e (new edition) p. 1247-1248]
contained a four carbon ring called lactam ring.
penicillins by producing penicillinase.
producing beta -lactamase. (3 lactamase are enzymes that break open the 13 lactam ring and deactivate the antibiotic.
cephalothin or cefazolin, and are resistant to them.
these are cephalosporins containing oxyiminio side chain e.g. ceftizoxime, cefotaxime,
ceftazidime, ceftriaxone (broad spectrum cephalosporins).
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Consequently, when these oxyimino side chain containing com- pounds were introduced they
were effective against a broad group of otherwise resistant bacterias.
(cefotaxime, ceftizoxime, ceftazidime).
were discovered which were resistant even to oxyimino containing cephalosporins e.g.
(cefotaxime, ceftazidime, ceftriaxone)
These bacterias are called ESBL bacterias
o Bacterias are classified as extended spectrum 13 lactamase (ESBL) producing bacteria, when a
simple point mutation occurs in genes normally responsible for beta lactamase mediated
resistance. The mutation usually responsible is (TEM).
o As a result of the mutation, organisms, are able to produce novel beta lactamases that can
hydrolyze all the b-lactam containing antibiotics which includes even the oxyimino group
containing cephalosporins (ceftizoxime, cefotaxime, ceftazidime, ceftriaxone), Aztreonam
and all the older b-lactam drugs.
o Because of their greatly extended substrate range these enzymes were called extended
ESBLS are capable of efficiently hydrolyzing
An important point
organisms are in the family. Enterobacteriaeae and has been discovered in almost all
members of the enterobacteriaceae family.
(Klebsiella pneumonia predominantly) and E. coli.
Treatment of ESBL’S
highly resistant to the hydrolytic activity of the b-lactamase.
(imipenem, meropenem) Meropenem is the most active with MIC generally lower than those
safely with b lactam / 13 lactamase inhibitor combinations are those involving the urinary
– In this instance 13 lactamase inhibitor concentration is high enough to counteract the hydrolytic
activity of ESBL’s clavulanic acid appears more emcient than sulbactam (It takes about eight
times more sulbactam to obtain a protection similar to that given by clavulanic acid).
Non 13 lactam antibiotics
Non 13 lactam antimicrobial agents (aminoglycosides, fluoro- quinolones) may be beneficial
however, co resistance rates against these agents are frequent.
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