Which antibiotics are best for UTIs?
It depends. [“Here we go again!” CKDEx Ed]
Why? It depends what we mean by a UTI. Loosely there are two ‘types’:
- Uncomplicated UTIs – these mainly affect the bladder (cystitis), are mild, and are usually treated with oral antibiotics. An ultrasound is usually not necessary
- Complicated UTIs – these mainly affect the kidney (pyelonephritis), and more severe, and are usually treated with intravenous (IV) antibiotics. An ultrasound is usually done.
Note 1. The words ‘uncomplicated’ and ‘complicated’ are not easy to define. ‘Uncomplicated’ is usually taken to mean a UTI with an (anatomically) normal urinary tract. Whereas ‘complicated’ means an abnormal urinary tract, and there is an underlying structural problem somewhere (that you need to find, as it is ‘causing’ the UTI). But this is not entirely true.
For example, after an acute pyelonephritis, the kidney may return to normal, and there was no structural problem in the urinary tract.
Note 2. Health professionals (especially doctors) .. please avoid the phrase ‘urosepsis’. It has no meaning. We don’t talk about ‘gastrosepsis’ or ‘cerebrosepsis’. It is better to use correct terminology, e.g. ‘this young lady has a R sided acute pyelonephritis and is unwell. She requires hospital admission and IV fluids and antibiotics”. Not ‘urosepsis’.
The antibiotics most commonly used to treat uncomplicated urinary tract infections (UTIs) include:
- Combination antibiotics – e.g.
- Cotrimoxazole (‘Septrin’; trimethoprim and sulfamethoxazole)
- Amoxicillin/clavulanic acid (Augmentin)
- Trimethoprim
- Penicillins – e.g. amoxycillin
- Cephalosporins – e.g. cephalexin
- Fluoroquinolones – e.g. ciprofloxacin, now rarely used
- Nitrofurantoin.
Note. Some mild UTIs will get better with home therapies and no antibiotics.
What bacteria cause UTIs?
80% of uncomplicated urinary tract infections are caused by Escherichia coli, followed by Staphylococcus saprophyticus in as many as 5% to 15% of cases. Enterococci, Klebsiella species and Proteus mirabilis account for a small percentage of overall infections.
So the choice of antibiotics have to cover these organisms.
Summary
We have described which antibiotics are best for UTIs. UTIs are a common bacterial infection that usually require treatment with antibiotics. The most commonly prescribed antibiotics for UTIs are amoxycillin, cephalexin, nitrofurantoin, trimethoprim, and trimethoprim-sulfamethoxazole. We hope it has been helpful.
Last Reviewed on 19 April 2024