#ESBL bacteria ❤️🔥
It stands for Extended Spectrum β-Lactamase.
These bacteria produce enzymes that break down most β-lactam antibiotics.
The most common bacteria that produce ESBL are Klebsiella – Proteus – E. coli
These bacteria are:
🚫 Resistant to penicillins alone
But… when penicillins are combined with a β-lactamase inhibitor (such as Clavulanic acid, Sulbactam, or Tazobactam)
they become sensitive to these combination antibiotics.
So, for example:
An ESBL isolate will be resistant to Amoxicillin alone,
but sensitive to Amoxicillin–Clavulanate (AUG).
As for the cephalosporins:
🚫 Resistant to 1st and 2nd generation cephalosporins
🚫 Resistant to most 3rd-generation cephalosporins
Meaning Ceftriaxone, Cefotaxime, and Ceftazidime are useless—
no matter what the plate shows (R or S),
clinically the result is R across the board.
🚫 It is usually resistant to 4th-generation Cefepime
It may appear Sensitive or Resistant on the plate,
and clinically it may work or fail depending on enzyme strength.
That’s why we don’t rely on it 100%.
🚫 And it is also resistant to the Monobactam (Aztreonam).
So how do we detect ESBL phenotypically?
If you place Ceftazidime or Cefotaxime next to Augmentin (AMC),and you see a #Keyhole expanding between them…
then the isolate is ESBL confirmed ✨
This happens because clavulanic acid inhibits the ESBL enzyme diffuse toward the 3rd-generation cephalosporin to regain its activity which creates the classic keyhole-shaped synergy zone.
Now for the correct treatment…
In severe infections:
👑 Carbapenems are the kings
Meropenem – Imipenem – Ertapenem
In mild, non-systemic, non-critical infections: Tazocin may work,
and Augmentin can be used in uncomplicated UTIs.
Although combinations may show good lab results, #IDSA recommends avoiding combination therapy in critically ill patients or in severe systemic infections, and to use Carbapenems instead.
In short, how do we differentiate between ampC and ESBL?
ESBL → Keyhole formation
ESBL is usually sensitive to FOX and combinations (AUG)
ampC → D-shape induction
ampC is resistant to FOX and to combinations (AUG)
Reposted via @bacteriologia
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