AMPICILLIN
Ampicillin is a broad-spectrum penicillin antibiotic that, although not directly involved in the process of anesthesia, plays an important role in the perioperative period for preventing and managing infections related to surgical procedures. The importance of ampicillin in the context of anesthesia can be highlighted by the following factors:
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Surgical prophylaxis: Ampicillin can be used as a prophylactic antibiotic before surgery to reduce the risk of postoperative infections, particularly in cases involving the gastrointestinal or genitourinary tracts. By targeting common susceptible bacteria, such as gram-positive and some gram-negative organisms, ampicillin helps prevent surgical site infections (SSIs) when administered before the procedure. Proper timing and dosing are essential to ensure adequate tissue concentration during the surgery.
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Treatment of infections: In some cases, ampicillin may be used to treat established infections in the perioperative period, such as wound infections, urinary tract infections, or intra-abdominal infections. The choice of ampicillin as a treatment option depends on the suspected or confirmed causative organisms and their susceptibility patterns.
Its mechanism of action, like other beta-lactam antibiotics, involves the inhibition of bacterial cell wall synthesis. This is achieved through the following steps:
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Binding to penicillin-binding proteins (PBPs): PBPs are a group of enzymes located in the bacterial cell membrane that play a critical role in the synthesis and maintenance of the bacterial cell wall. Ampicillin and other beta-lactam antibiotics bind to these proteins, interfering with their normal function.
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Inhibition of peptidoglycan synthesis: The bacterial cell wall is primarily composed of a complex structure called peptidoglycan, which provides mechanical strength and rigidity to the cell. PBPs are responsible for cross-linking the peptidoglycan strands to form a stable and robust cell wall. By binding to PBPs, ampicillin inhibits the cross-linking process, impairing the synthesis of the peptidoglycan layer.
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Activation of autolytic enzymes: The inhibition of peptidoglycan synthesis can lead to the activation of bacterial autolytic enzymes, which further contribute to the breakdown of the cell wall. This results in bacterial cell lysis and death.
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Bactericidal effect: The overall effect of ampicillin's action on the bacterial cell wall is bactericidal, meaning it kills the bacteria rather than just inhibiting their growth. This is particularly important for managing infections where the immune system alone may not be sufficient to clear the infection.
Key points about Ampicillin
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Binds to bacterial cell wall, resulting in cell death.
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Bactericidal action of penicillins reflects the ability to interfere with the synthesis of peptidoglycan, which is an essential component of cell walls of susceptible bacteria.
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The major mechanism of resistance to the penicillins is bacterial production of beta-lactamase enzymes that hydrolyze the beta-lactam ring, which renders the antimicrobial molecule inactive.
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Ampicillin has an antibacterial spectrum similar to that of penicillin G but are more effective against gram negative bacilli.
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Its spectrum encompasses not only pneumococci, meningococci, gonococci, and various streptococci but also a number of gram-negative bacilli, such as Haemophilus influenzae and Escherichia coli.
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Among the penicillins, ampicillin is associated with the highest incidence of skin rash.
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Formulation with a beta-lactamase inhibitor, such as sulbactam, protects ampicillin, respectively, from enzymatic hydrolysis and extends its antimicrobial spectra.