Mechanism of action
Ampicillin/sulbactam is a combination of a β-lactam antibiotic and a β-lactamase inhibitor. Ampicillin works by binding to penicillin-binding proteins (PBPs) to inhibit bacterial cell wall synthesis. This causes disruption of the bacterial cell wall and leads to bacterial cell death. However, resistant pathogens may produce β-lactamase enzymes that can inactivate ampicillin through hydrolysis. This is prevented by the addition of sulbactam, which binds and inhibits the β-lactamase enzymes. It is also capable of binding to the PBP of Bacteroides fragilis and Acinetobacter spp., even when it is given alone. The activity of sulbactam against Acinetobacter spp. seen in in-vitro studies makes it distinctive compared to other β-lactamase inhibitors, such as tazobactam and clavulanic acid. Chemistry
Ampicillin sodium is derived from the basic penicillin nucleus, 6-aminopenicillanic acid. Its chemical name is monosodium (2S, 5R, 6R)-6-[(R)-2-amino-2-phenylacetamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate. It has a molecular weight of 371.39 grams and its chemical formula is C16H18N3NaO4S. Sulbactam sodium is also a derivative of 6-aminopenicillanic acid. Chemically, it is known as either sodium penicillinate sulfone or sodium (2S, 5R)-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylate 4,4-dioxide. It has a molecular weight of 255.22 grams and its chemical formula is C8H10NNaO5S. Ampicillin/sulbactam is also used when the cause of an infection is not known (empiric therapy), such as intra-abdominal infections, skin infections, pneumonia, and gynecologic infections. It is active against a wide range of bacterial groups, including Staphylococcus aureus, Enterobacteriaceae, and anaerobic bacteria. Importantly, it is not active against Pseudomonas aeruginosa and should not be used alone when infection with this organism is suspected or known.
Anaerobes: Clostridium species, Peptococcus species, Peptostreptococcus species, Bacteroides species including B. fragilis.Gynecological Infections
Ampicillin/sulbactam can be used to treat gynecological infections caused by beta-lactamase producing strains of Escherichia coli, and Bacteroides (including B. fragilis).Bone and joint infections
Ampicillin/sulbactam can be used in the treatment of bone and joint infections caused by susceptible beta-lactamase producing bacteria.Intra-abdominal infections
Ampicillin/sulbactam can be used to treat intra-abdominal infections caused by beta-lactamase producing strains of Escherichia coli, Klebsiella (including K. pneumonia), Bacteroides fragilis, and Enterobacter.Skin and skin structure Infections
This medication can be used to treat skin and skin structure infections caused from beta-lactamase-producing strains of Staphylococcus aureus, Enterobacter, Escherichia coli, Klebsiella (including K. pneumoniae), Proteus mirabilis, Bacteroides fragilis, and Acinetobacter calcoaceticus. Examples of skin conditions treated with ampicillin-sulbactam are moderate to severe diabetic foot infections and type 1 Necrotizing fasciitis, commonly referred to as "flesh-eating bacteria". Contraindications
Ampicillin/sulbactam is contraindicated in individuals who have a history of a penicillin allergy. Symptoms of allergic reactions may range from rash to potentially life-threatening conditions, such as anaphylaxis. Patients who have asthma, eczema, hives, or hay fever are more likely to develop undesirable reactions to any of the penicillins. Adverse effects
Reported adverse events include both local and systemic reactions. Local adverse reactions are characterized by redness, tenderness, and soreness of the skin at the injection site. The most common local reaction is injection site pain. It has been reported to occur in 16% of patients receiving intramuscular injections, and 3% of patients receiving intravenous injections.