A guide to the major antibiotics

Posted on 6 November 2018

Yes, there are different kinds of antibiotics. Here’s your guide to the main types: how they work, what they treat, and what their potential side effects could be.

As Dr Amima Sundas, a physician at Mediclinic Newcastle, explains, there are many different antibiotics used to many different infections. “Prescribing doctors should use specific antibiotics to treat certain infections, looking at the treatment and antibiotic resistance patterns in their communities to see which infection will respond to which antibiotic,” she says.

Each type of antibiotic only works against certain types of bacteria or parasites, which is why it is so important that patients seek medical advice before they consider going on a course of antibiotics. Various antibiotics are available and are sold under various different brand names. They are usually grouped together based on how they act. Some of the most commonly used types are outlined below:


Penicillins act by weakening the bacterial cell wall and allowing water to enter, causing the cell to either die or burst. These antibiotics are widely used to treat a range of infections – particularly chest, skin and upper respiratory tract infections.


These broad-spectrum antibiotics work in a similar way to penicillin and can be used to treat a wide range of infections. They’re also effective for treating more serious infections like septicaemia and meningitis and are used to treat Haemophilus influenza, a type of bacterial infection (not to be confused with the influenza ‘flu’ virus). Because of their chemical similarity to penicillin, some patients who are allergic to penicillin may also be allergic to cephalosporins.


Macrolides are especially effective for treating lung and chest infections. Unfortunately, macrolide resistance in Group A beta-hemolytic streptococci (also known as GABHS, a bacteria that’s known to cause pneumonia, meningitis and upper respiratory tract infections) is a major concern for doctors, so use of these agents tends to often be restricted to patients who are allergic to penicillin.


Aminoglycosides work by causing abnormal protein production and cell membrane damage in bacteria – but because of their potential side effects, they’re usually only used to treat serious illnesses like septicaemia. Those side effects are quite nasty, and could lead to kidney damage and hearing loss. They can’t be taken orally, because they break down quickly inside the digestive system, so they have to be given by injection.


This family of broad-spectrum antibiotics are used to treat a wide range of infections, and they work by interfering with the reproduction of bacterial DNA.  There’s growing antibiotic resistance to quinolones which are used in the management of typhoid fever diarrhoeal and urinary tract infections amongst others.


These antibiotics interfere with bacterial protein synthesis, which makes them effective for a wide range of infections. Their most common use is as a malaria prophylaxis, and in the treatment of acne.

Have you been contributing to antibiotic resistance?

Published in Expert Articles

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