What kind of bacteria does ampicillin kill?

Posted on  March 4, 2021, Edited by Jason, Category  

What is ampicillin?

1. Definition

Ampicillin is a beta lactam antibiotic that can treat many bacterial infections. Indications include respiratory infections, urinary tract infections, meningitis, salmonella infections, and endocarditis. It can also be used to prevent group B streptococcal infections in newborns, and it can be administered by oral, intramuscular and intravenous injections. Ampicillin was first discovered in 1961, and it was listed on the World Health Organization's standard list of essential medicines and is one of the essential drugs in the basic public health system.

On October 27, 2017, the list of carcinogens published by the International Agency for Research on Cancer of the World Health Organization was initially compiled for reference. Ampicillin was included in the list of three types of carcinogens.

2. Pharmacological effects

Ampicilina is a semi-synthetic broad-spectrum penicillin. Ampicillin mechanism of action is that it will prevent the synthesis of the bacterial cell wall, so it can not only inhibit its proliferation, but also directly kill the bacteria. The effect on gram-positive bacteria is similar to that of penicillin. It has better effect on Streptococcus viridans and Enterococcus, but has poor effect on other bacteria.

It has no effect on penicillin-resistant Staphylococcus aureus. Among the gram-negative bacteria, Neisseria gonorrhoeae, meningococcus, influenza bacillus, bacillus pertussis, Escherichia coli, typhoid and paratyphoid bacillus, dysentery bacillus, Proteus mirabilis, Brucella, etc. are sensitive to this product, but easy to develop resistance. Pneumoniae, indole-positive Proteus, and Pseudomonas aeruginosa are not sensitive to this product.

3. Ampicillin vs Amoxicillin

Ampicillin and amoxicillin are antibiotics, but their classification is different. Ampicillin can treat a variety of bacterial infections. It is often used for respiratory infections and urinary system infections. It can also be used to treat some reactions caused by endocarditis and salmonella. Amoxicillin is mainly used for sterilization, and its ability to penetrate the cell wall is very strong, so preparations are widely used at present, including capsules and tablets, as well as granules.

The difference between amoxicillin and ampicillin is that the molecule of amoxicillin has one more hydroxyl group than ampicillin. It is this difference that greatly reduces the lipophilicity of amoxicillin, and thus the oral bioavailability of amoxicillin has been greatly improved compared to ampicillin.

Therefore, when the same dose of amoxicillin and ampicilina is given to livestock and poultry, the bioavailability of amoxicillin is much higher than that of ampicillin. For example, give the same doses of amoxicillin and ampicilina orally to dogs, the bioavailability of ampicilina is about 30%, while the bioavailability of amoxicillin is 65%.

Amoxicillin is a penicillin antibiotic, having good antibacterial activity against Streptococcus pneumoniae, Streptococcus hemolyticus, Staphylococcus non-penicillinase, Enterococcus faecalis and other aerobic gram-positive cocci, Escherichia coli, Proteus mirabilis, Salmonella Bacteria, Haemophilus influenzae, Neisseria gonorrhoeae and other aerobic gram-negative bacteria that do not produce beta lactamase and Helicobacter pylori. Amoxicillin plays a bactericidal effect by inhibiting the synthesis of bacterial cell walls, allowing bacteria to quickly become spheroids and dissolve and rupture.

Ampicillin capsules are quite stable to gastric acid and are well absorbed orally. Ampicillin is mainly used for urinary system, respiratory system, biliary tract, intestinal infections and meningitis, endocarditis caused by sensitive bacteria; it can also be used for the treatment of typhoid fever and paratyphoid fever; it can also be used for urinary tract and respiratory tract infections.

The indications of ampicilina and amoxicillin are similar, and the treatment effect for various germs is also good, but there are some slight differences. Patients should not find it difficult to choose, when you need to take this type of medicine, your doctor will help you choose a more suitable drug according to your condition, and the cure effect can be achieved as long as the correct medication is used.

Ampicillin uses


1. Indications

This product is mainly used for urinary system, respiratory system, biliary tract, intestinal infections, meningitis, endocarditis, etc.

2. Clinical application

Ampicilina is less effective than penicillin against most Gram-positive bacteria. But it has a strong effect on most gram-negative bacteria, such as Escherichia coli, Proteus, Salmonella, Haemophilus, Brucella and Pasteurella, similar to or slightly stronger than chloramphenicol and tetracycline. But the toxic effect is less than that of chloramphenicol and tetracycline, and it is ineffective against resistant Staphylococcus aureus and Pseudomonas aeruginosa.

Ampicillin is widely used in human and livestock lung and urinary tract infections caused by sensitive bacteria, and certain Chemicalbook infections caused by gram-negative bacilli, such as human meningitis, endocarditis, etc.; foal, calf pneumonia, and Pasteurella bovis diseases, pneumonia, mastitis, porcine infectious pleuropneumonia, pullorum, avian typhoid, etc.

Ampicillin is susceptible to the interference of β-lactamase produced by bacteria and decomposes soon, thereby reducing its efficacy. In clinical practice, it is often used in combination with a synthetic beta lactamase inhibitor-sulbactam to increase its synergistic effect, which improves its antibacterial activity and expands its antibacterial spectrum. In addition, the combination of ampicillin and aminoglycoside antibiotics also has a synergistic effect, which can enhance the efficacy.

3. Ampicillin Dosage

A. Intramuscular Injection

  • For adults, 800,000 to 2 million units a day, divided into 3 to 4 doses.
  • For children, 25,000 units/kg, administered once every 12 hours.
  • Newborns (full-term birth): each time according to the weight of 50,000 units/kg, once every 12 hours in the first week of birth, once every 8 hours for those over a week, and once every 6 hours for severe infections.

B. Intravenous injection (Suitable for severe infections)

  • For adults, 2 to 20 million units a day, divided into 2 to 4 intravenous drips. The rate of administration cannot exceed 500,000 units per minute.
  • For children, 50,000 to 200,000 units/kg a day, divided into 2 to 4 intravenous drips.
  • For newborn (term birth): the same dosage as intramuscular injection.

Ampicillin Sulbactam

1. What is Sulbactam?

Sulbactam is an irreversible competitive beta lactamase inhibitor, which inhibits beat lactamase produced by Gram-positive and negative bacteria (except Pseudomonas aeruginosa). Single application is effective for peripheral infections of Neisseria gonorrhoeae and meningococcus; combined treatment of sulbactam and ampicillin, cefoperazone, piperacillin, mezlocillin and other sensitive bacteria in the respiratory tract, urinary tract, obstetrics and gynecology, and abdominal cavity Internal, skin and soft tissue, eye, ear, nose, and throat, bone and joint infections, as well as sepsis, meningitis, etc.

At present, sulbactam products produced in China are mainly ampicillin/sulbactam sodium combined preparations (unasyn) for intravenous or intramuscular injection.

Sulbactam has weak antibacterial activity and is slightly stronger than clavulanic acid. When used alone, it can only kill Neisseria gonorrhoeae and Acinetobacter. It has a strong inhibitory effect on most beta lactamases produced by gram-positive bacteria and gram-negative bacteria, but it has no effect on metal beta lactamase. The combination of sulbactam and penicillin or cephalosporin drugs generally has a significant synergistic effect, which greatly improves the antibacterial activity of the first two and expands the antibacterial spectrum.

When used alone, it is effective against gonococcal and meningococcal infections; sulbactam combined with ampicillin or cefoperazone can treat respiratory tract, urinary tract, obstetrics and gynecology, intra-abdominal cavity, skin and soft tissue, eyes, ears, nose and throat caused by sensitive bacteria Department and bone and joint infections, sepsis, meningitis, etc.

2. The role of ampicillin sulbactam

Ampicillin sulbactam is suitable for beta lactamase-producing Haemophilus influenzae, Moraxella catarrhalis, Neisseria gonorrhoeae, Staphylococcus, certain Escherichia coli, Klebsiella and Proteus mirabilis, Bacteroides fragilis, Acinetobacter, Enterococcus, etc. caused by hepatobiliary system, urinary system, skin and soft tissue infections. It is particularly suitable for mixed infections of aerobes and anaerobic bacteria, especially abdominal infections and pelvic infections.

This product is also effective against the above-mentioned infections caused by ampicillin-sensitive bacteria. This product is not suitable for infections caused by Pseudomonas aeruginosa, Citrobacter, Providencia, Enterobacter, Morgenella and Serratia. Adverse reactions include pain at the injection site, skin rash, occasional diarrhea, nausea, and transient increase in ALT and AST.

Ampicillin side effects 


1. Adverse reactions

The adverse reactions of ampicillin are similar to penicillin. Allergic reactions are common such as skin rash and urticaria, which have a higher incidence than other penicillins. Occasionally, anaphylactic shock, neutropenia, and thrombocytopenia are rare, abnormal liver function can be seen, and neurological symptoms such as convulsions may occur after high-dose intravenous administration.

Adverse reactions are more common in allergic reactions. Among them, rash is the most common, with an incidence rate of 3.1%~18%. It often appears 7 to 12 days after the start of treatment, manifested as urticaria or maculopapular rash. The incidence of skin rash with injection is higher than oral administration. People with renal insufficiency have a high incidence of skin rashes. There are reports of exfoliative dermatitis. And there has been reported that 8 cases of allergic dermatitis have different degrees of liver damage, which should be considered as allergic liver damage.

  • Skin rash is the most common adverse reaction, which usually occurs 5 days after medication, manifested as urticaria or maculopapular rash. The former is a typical rash of penicillin allergic reactions, and the latter has specificity to ampicillin. The incidence of injection administration is higher than that of oral administration.
  • Occasionally, granulocytes and thrombocytopenia may occur after medication.
  • Interstitial nephritis may occur in a few patients after medication.
  • A few patients have liver function abnormalities after medication.
  • Large doses of intravenous administration can cause neurotoxic symptoms such as convulsions. Infants may experience increased intracranial pressure after medication, manifested as bregma bulge.
  • Ampicillin-related enteritis is extremely rare.

2. Cautions

  • If severe persistent diarrhea occurs during the medication, it may be pseudomembranous enteritis, the medication should be stopped immediately, and the corresponding antibiotics should be used after diagnosis.
  • It decomposes quickly in weakly acidic glucose solution, so neutral infusion should be used as the solvent.
  • Ampicillin can stimulate the metabolism of estrogen or reduce its enterohepatic circulation, and reduce the efficacy of oral contraceptives.

3. Ampicillin Interactions

  • Combined with probenecid, aspirin, indomethacin and sulfa drugs, it can reduce the excretion of penicillin drugs, increase the blood concentration of penicillins, and increase the effect and the toxicity.
  • Combined use with tetracyclines, erythromycin, chloramphenicol and sulfonamides and other antibacterial drugs may reduce the antibacterial effect of this product.
  • The combined application of ampicillin and chloramphenicol has different effects on the antibacterial effects of influenza bacilli in vitro. Chloramphenicol has no antagonism to ampicillin at high concentrations (5~10 mg/L). At low concentrations (1~2 mg/L), it can weaken the bactericidal effect of ampicillin, but has no effect on chloramphenicol. And when the two drugs are used in the treatment of bacterial meningitis, the incidence of long-term sequelae is higher than used alone.
  • Combination with warfarin can enhance the anticoagulant effect.
  • Kanamycin can enhance the in vitro antibacterial effect of ampicillin against Escherichia coli, Proteus and Enterobacter.
  • Gentamicin can enhance the in vitro bactericidal effect of ampicillin on group B streptococci.


Ampicillin is a beta lactam antibiotic. It was considered one of the essential drugs in the public health system in the 1960s, and in 2017 it was listed as one of the three carcinogens by the World Health Organization. Therefore, care must be taken when applying such drugs.

BALLYA provides a ballya-ampicillin-test to tell you if there are ampicillin residues in foods or feed.


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