Active Ingredients

Acylaminopenicillins – Effect, Application & Risks


Acylaminopenicillins are broad -spectrum antibiotics that are primarily effective against gram-negative bacteria . Their individual active ingredients are used in particular to combat so-called hospital germs such as Pseudomonas aeruginosa or enterococci . However, the acylaminopenicillins are not acid and beta-lactamase stable.

Was sind Acylaminopenicilline?

Acylaminopenicillins are broad-spectrum antibiotics belonging to the penicillin group . A special feature of their molecular structure is the possession of a beta-lactam ring. In the case of the acylaminopenicillins, however, the beta-lactam ring is not protected against attack by the so-called beta-lactamase, which is produced by certain bacteria. Furthermore, the acylaminopenicillins are also not stable against the influence of acids.

Acylaminopenicillins are used in particular to combat gram-negative bacteria of the Pseudomonas or Proteus species. As broad-spectrum antibiotics, however, they can also act against some gram-positive bacteria.

The main representatives of the group of acylaminopenicillins are the active substances azlocillin , mezlocillin , piperacillin or ampicillin . Because of their beta-lactamase and acid instability, the acylaminopenicillins are administered perenterally in the form of venous or muscular infusions .

Pharmacological effect on body & organs

Like all penicillins, the acylaminopenicillins also interfere with the metabolism of bacteria. After penetrating the bacterial cell, they inhibit the formation of the bacterial cell wall. Their beta-lactam ring opens in the bacterium’s cell plasma and, when open, binds to the bacterial enzyme D-alanine transpeptidase. 

With the help of D-alanine transpeptidase, alanine residues in the cell wall of the bacterial cell are connected to one another. By blocking this enzyme , this linkage can no longer take place. As a result, the bacterium loses the ability to continue dividing and dies in the process.

Bacterial development of antibiotic resistance to the antibiotics of the penicillins is based on the bacterium’s ability to synthesize the enzyme beta-lactamase. The beta-lactamase cleaves the beta-lactam ring of the antibiotic before it can engage in metabolism. The acylaminopenicillins are also not protected against attack by beta-lactamase, since the ring in the molecule is freely accessible. Nevertheless, acylaminopenicillins are able to fight resistant germs when used in a special way.

Since acylaminopenicillins are not acid and beta-lactamase stable, they must be injected parenterally. In this way, they immediately enter the bloodstream via a venous injection . Injection into the muscle is also possible. Immediately after administration, the active ingredient then penetrates into the cell of the bacterium and prevents further build-up of the bacterial cell wall. The bacterium is not primarily killed. However, it dies because it cannot divide any further.

Acylaminopenicillins are often used in combination with beta-lactamase inhibitors to overcome the extensive antibiotic resistance of the bacteria to be combated. As the name suggests, the beta-lactamase inhibitor inhibits the activity of the bacterial enzyme beta-lactamase and can thus enhance the effect of the acylaminopenicillins.

The half-life of acylaminopenicillins in the body is only about one hour. 60 percent of them are then excreted largely unchanged via the kidneys .

Medical Application & Use

Acylaminopenicillins are widely used as broad-spectrum antibiotics to combat infections with the opportunistic germs Pseudomonas aeruginosa or enterococci. As a rule, these bacteria are not very infectious. However, they can cause serious infections in immunocompromised people .

These are mostly nosocomial infections (infections with hospital germs). These germs enter the body particularly through wounds on the skin or mucous membranes . They often cause pneumonia in patients in intensive care units . Furthermore, they can cause urinary tract diseases after urological operations or the use of permanent catheters , purulent skin infections in wounds and even sepsis .

Piperacillin has the widest range of applications among the acylaminopenicillins and thus also among the penicillins . It is effective against gram-negative bacteria such as enterobacteria , Pseudomonas aeruginosa and anaerobes as well as against gram-positive germs. Although its effect against gram-positive bacteria is worse than that of some other penicillins, it is considered sufficient for a broad-spectrum effect.

In addition to its use in combating hospital germs, piperacillin is also used in urogenital infections, gonorrhea , abdominal abscesses , pneumonia, sepsis, bacterial endocarditis, wound and burn infections, and bone and joint infections .

Piperacillin is administered both as a single preparation and in combination with beta-lactamase inhibitors. The active ingredient azlocillin is particularly effective against enterococci and Pseudomonas aeruginosa. It is often used together with cephalosporin in very severe infections caused by unknown pathogens.

Mezlocillin also has a broad spectrum of activity. However, it works less well than azlocillin in Pseudomonas infections. While ampicillin is also a broad-spectrum antibiotic, its overall potency is lower than that of all other acylaminopenicillins.

Risks & side effects

In addition to the many positive effects, the use of acylaminopenicillins also harbors risks in some cases. Before they are used, it must always be checked whether there is a hypersensitivity to penicillins. So it is possible that there is a cross-allergy with other beta-lactam antibiotics. If this is the case, there is a risk of anaphylactic shock when using acylaminopenicillins . For this reason, the use of acylaminopenicillins is absolutely contraindicated in the case of an existing hypersensitivity to penicillin.In rare cases, other unwanted side effects may occur. The occurrence of so-called pseudoallergies with skin reddening , skin rashes and itching is possible.

Drug fever, eosinophilia, painless swelling of the skin ( Quincke’s edema ), anemia , vascular inflammation , kidney inflammation or even a permanent increase in platelets are very rarely observed. Overall, the risks are roughly the same as those observed with the use of other antibiotics.

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Hello! I am Lisa Newlon, and I am a medical writer and researcher with over 10 years of experience in the healthcare industry. I have a Master’s degree in Medicine, and my deep understanding of medical terminology, practices, and procedures has made me a trusted source of information in the medical world.