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Extended-spectrum beta-lactamases (ESBLs)

Extended-spectrum beta-lactamases (ESBLs)

Extended-spectrum beta-lactamases (ESBLs) are chemicals (enzymes) that can be made by some germs (bacteria). The ESBLs can make some antibiotics ineffective. This makes the infection caused by the bacteria much harder to treat. 

ESBL-producing bacteria is just one example of a rapidly growing problem of antibiotics being ineffective in treating certain infections.

There are still a few antibiotics that can be used to treat infections caused by ESBL-producing bacteria. However, current antibiotics will continue to become less effective unless used only when really needed. It is also very important to use antibiotics in the correct dose for the full recommended course of treatment.

Although ESBLs can be made by different bacteria, they are most often made by E. coli (more correctly called Escherichia coli). Therefore, the remainder of this article refers to E. coli. Other bacteria that can also make ESBLs include the species called Klebsiella.

What is E. coli?

E. coli (more correctly called Escherichia coli) is a germ (bacterium). There are many strains (subtypes) of E. coli. Many of the strains of E. coli are usually harmless and live in the gut of healthy people. However, some strains are a cause of common infections such as urine infections and gut infections (gastroenteritis).  

The following conditions may be caused by E. coli infections:

Urinary tract infections (UTIs)

For example, cystitis, kidney infections and other 'urine infections'. These are the most common infections caused by E. coli. About 9 in 10 UTIs are caused by strains of E.coli. Many of the strains are those which live harmlessly in the gut but can cause a UTI if they get into the bladder or other parts of the urinary tract.

Infection of the gut (gastroenteritis)

This is commonly due to various strains which do not normally live in the gut. Gastroenteritis can cause symptoms of runny stools (diarrhoea), being sick (vomiting), high temperature (fever) and tummy (abdominal) pain. The source of the infecting strains is often from contaminated food ('food poisoning') or from other people who have the infection. Traveller's diarrhoea is often caused by a strain of E. coli.

Intra-abdominal infections

These are infections that occur inside the abdomen, often when a part of the gut is damaged or punctured (perforated). This allows the normally harmless E. coli germs (bacteria) that live in the gut to get into the abdomen and cause infection. For example, the following can occur after a burst appendix or following a stab wound to the abdomen:

  • Inflammation of the thin layer of tissue lining the abdomen (the peritoneum). This is called peritonitis.
  • An abdominal collection of pus (an abscess).

Other infections

Other infections that are sometimes caused by strains of E. coli include:

So, in fact, practically any area of the body can be infected with E. coli, although some areas are only rarely infected.

Other diseases

Other diseases associated with E. coli include haemolytic uraemic syndrome (HUS) and thrombotic thrombocytopenic purpura (TTP). These are rare but serious diseases that occur as a result of a poison (toxin) that some strains of E. coli make. The most important toxin-releasing strain is called 'vero cytotoxin-producing Escherichia coli O157'. This is sometimes called VTEC O157 or E. coli O157. See the separate leaflet called E. Coli and VTEC O157 for more details.

Recently, there has been concern that some strains of E. coli can produce small proteins (enzymes) called extended-spectrum beta-lactamases (ESBLs). These enzymes are significant because, when they are produced by the germs (bacteria), they can make the bacteria resistant to certain commonly used antibiotic medicines. This means that the bacteria can continue to multiply, causing more severe infection and becoming more difficult to treat.

Most infections caused by ESBL-producing E. coli have occurred in people with other medical conditions who are already very sick, and also in elderly people. People who have been taking antibiotics for other reasons or who have recently been in hospital are also at higher risk.

There are only a few antibiotics that can be used to treat infections caused by ESBL-producing E. coli. Most ESBL-producing E. coli are resistant to many commonly used antibiotic medicines such as cephalosporins and penicillins. Two antibiotics that have been effective are nitrofurantoin and fosfomycin.

Resistance of germs (bacteria) to antibiotics is becoming a very big problem. ESBL-producing E. coli is just one example of bacteria becoming resistant to antibiotics. It is essential that antibiotics are only used when necessary and, when they are needed, the full dose and full course of the antibiotic must be taken. This will help to reduce the number of bacteria that are becoming resistant to antibiotics.

Preventing the spread of infection

Many infections caused by ESBL-producing E. coli are not spread from person to person, such as urinary tract infections. However, if the bacteria causes an infection in your gut (gastroenteritis) then it is essential to take the following steps to prevent the spread of infection to others:

  • Wash your hands thoroughly after going to the toilet. Ideally, use liquid soap in warm running water but any soap is better than none. Dry properly after washing.
  • Don't share towels and flannels.
  • Don't prepare or serve food for others.
  • Regularly clean the toilets that you use, with disinfectant. Wipe the flush handle, toilet seat, bathroom taps, surfaces and door handles with hot water and detergent at least once a day. Keep a cloth just for cleaning the toilet (or use a disposable one each time).
  • Stay off work, college, etc, until at least 48 hours after the last episode of diarrhoea or being sick (vomiting).

Further reading & references

  • Extended-spectrum beta-lactamases (ESBLs); Public Health England
  • Curello J, MacDougall C; Beyond Susceptible and Resistant, Part II: Treatment of Infections Due to Gram-Negative Organisms Producing Extended-Spectrum beta-Lactamases. J Pediatr Pharmacol Ther. 2014 Jul;19(3):156-64. doi: 10.5863/1551-6776-19.3.156.
  • Ha YE, Kang CI, Cha MK, et al; Epidemiology and clinical outcomes of bloodstream infections caused by extended-spectrum beta-lactamase-producing Escherichia coli in patients with cancer. Int J Antimicrob Agents. 2013 Nov;42(5):403-9. doi: 10.1016/j.ijantimicag.2013.07.018. Epub 2013 Sep 7.
  • Harris PN, Tambyah PA, Paterson DL; beta-lactam and beta-lactamase inhibitor combinations in the treatment of extended-spectrum beta-lactamase producing Enterobacteriaceae: time for a reappraisal in the era of few antibiotic options? Lancet Infect Dis. 2015 Apr;15(4):475-85. doi: 10.1016/S1473-3099(14)70950-8. Epub 2015 Feb 23.
  • Rawat D, Nair D; Extended-spectrum beta-lactamases in Gram Negative Bacteria. J Glob Infect Dis. 2010 Sep;2(3):263-74. doi: 10.4103/0974-777X.68531.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but makes no warranty as to its accuracy. Consult a doctor or other healthcare professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Colin Tidy
Current Version:
Dr Colin Tidy
Peer Reviewer:
Dr Hayley Willacy
Document ID:
29149 (v1)
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