conical flasks

Looking at the broad-spectrum of penicillins

Broad spectrum antibiotics are those which show bacteriostatic or bactericidal properties against multiple families of bacteria.


One of the most common uses for broad spectrum antibiotics is in prophylaxis, also known as preventative medicine.

Although hospitals uphold rigorous hygiene requirements in their operating theatres it is impossible to eliminate every single bacterium. As such, before a surgery, doctors will often administer broad spectrum antibiotics to patients in order to eliminate any bacteria which could enter the body whilst the surgery is being performed. This measure results in fewer preventable deaths post-surgery and reduces complications that may arise from bacterial inflammation around the site of a recent operation.


Sometimes bacterial inflammations can be life threatening, resulting in death if not treated promptly. Meningitis is condition brought about by inflammation of the protective membranes of the brain and spinal cord. The cause of this inflammation can be due to bacteria, viruses or a combination of the two. As prompt treatment is required in order to alleviate the symptoms of inflammation a cocktail of antibiotics and antivirals is administered.

Once the patient has been stabilised a thorough screening of the cerebrospinal fluid can be carried out, if required, in order to ascertain precisely which infectious microorganism is the cause of the inflammation. At this point a more specific treatment can be formulated which selectively targets the pathogen.

In general practice

Ampicillin is a generic brand antibiotic commonly prescribed for the general symptoms of bacterial infection. The drug is generic as the original patent for production has expired. This allows for other companies to make copies of this medicine, so long as their products have acceptably similar pharmacodynamic properties – how a medicine interacts with the organism it is administered to.

This increased production of generic antibiotics can have a positive effect on consumers by lowering the costs of medicines. When the monopoly a company holding the brand patent had is broken competition between producing companies can lower the prices of medicines significantly.

However, a large supply of cheap antibiotics can lead to over-prescription of broad spectrum antibiotics where a specific medicine would have been more effective. As laboratory analyses to identify the cause of infection are expensive and patient throughput is often assessed at GP practices it can often be simpler to prescribe broad spectrum antibiotics, such as ampicillin, to patients with general symptoms.

Though this can be effective in treating the cause of infection it can also lead to increased antibacterial resistance if too low a dose is used, the course of treatment is stopped early or the bacteria is only partially effected by the medicine.

In order to tackle the growing threat of antibacterial resistance the UK government’s National Institute for Health and Care and Excellence (NICE) has set out guidelines to GPs encouraging the shortest and most effective courses of treatment as well as encouraging hospitals to screen microbiological samples from the patient before prescribing a broad spectrum antibiotic.

Though antibiotic resistance continues to be a growing concern it is hoped that greater regulation and control over the prescription and distribution of antibiotics can stop, or at least reduce the rate of spread, of antibacterially resistant species.

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Exploring Everyday Chemistry

University of York