Extended Spectrum Beta-Lactamases (ESBLs) & ESBL Infection

ESBL-Producing Bacteria

Certain strains of bacteria are resistant to treatments with commonly used antibiotics such as penicillin and cephalosporins. These bacteria produce enzymes known as Extended Spectrum Beta-Lactamases or ESBLs for short. The ESBL enzyme breaks down and destroys most antibiotics causing them to be inactive, which is why they are not effective against infections caused by these types of bacteria. ESBL producing bacteria were first isolated and discovered in Europe in 1983 but are now a world-wide problem.

The term ESBLs is commonly used to refer to bacteria that produce Extended Spectrum Beta-Lactamase enzyme.

Which bacteria produce ESBLs?

ESBLs are resistant to most types of antibiotics (third generation). The majority of ESBL producing strains are either klebsiella pneumoniae (K. pneumoniae), klebsiella oxytoca (K. oxytoca) and Escherichia coli (E. coli). The ESBL producing strains of E. coli are different from the E. coli O157 that cause food poisoning infections. The ESBLs that E. coli most often produce are called CTX-M enzymes.

A few other types of bacteria have been less frequently associated with ESBLs production and these include Enterobacter spp., Salmonella spp., Morganella morganii, Proteus mirabilis, Serratia marcescens and Pseudomonas aeruginosa.

What types of illnesses and infections do Bacteria which produce ESBL cause?

In most fit and healthy individuals ESBL is usually not a problem. In fact many people have ESBL-producing E-coli bacteria in their bowels and they are completely harmless. This is known as colonisation or carriage because an individual can feel well without any signs or symptoms of infection whilst carrying the bug.

ESBLs cause illness and infection when they get into an area of the body where they are not usually found or in an individual that is elderly or immunocompromised.

A urinary tract infection is the most commonly caused infection by ESBL producing E. Coli but more serious life-threatening infections of the blood and lungs can also occur. These infections are often very difficult to treat due to their resistance to antibiotics.

Can ESBL infections spread between individuals ?

If appropriate hygiene and attention to cross-contamination protocols are not observed then ESBL-producing bacteria can be spread from person-to-person. The bug can be transmitted on unwashed hands or contaminated surfaces and equipment that has not been sterilised. Human cross-infection happens both in the hospital and also in the community. It is important that all careers ensure they wash their hands before and after every contact and wear appropriator protective barriers (gloves and aprons) as required. Poor hygiene is the most common cause of spread from person to person.

How is an infection caused by ESBL producing bacteria diagnosed ?

If a patient is suspected to have an infection then a swab or or specimen of the infected area will be taken and sent to the microbiology lab for testing. It is very important that diagnosis of ESBL is made quickly so that the most appropriate treatment can be prescribed quickly.

Who is at risk of contracting an infection by ESBL-producing bacteria?

People at risk are those exposed to patients who are already infected or individuals who have a poor immune system or the elderly. Other groups of people at risk from ESBL infection are people that have had repeated long term antibiotic treatment and built up a resistance or those that have had a long hospital stay or have a urinary catheter or cannula in place.

Can infections caused by ESBL-producing bacteria be treated?

There are a limited number of oral and intravenous antibiotics that are effective against these bacteria. The key is quick diagnosis so that any ineffective antibiotic treatment is stopped immediately. It is very important that the right antibiotics are prescribed at the correct dose for the appropriate length of time and only when required. Drug charts are monitored regularly and any unnecessary antibiotics are stopped.

It is recommended that patients infected with ESBLs are isolated from other patients in hospital to try and prevent the cross infection of other patients where possible.

The difficulty with treatment is due to the fact that ESBLs are able to destroy and inactivate most broad spectrum cephalosporin and monobactam antibiotics such as cefotaxime, ceftriaxone, ceftazidime and aztreonam.

However, ESBLs are ineffective against cephamycins, such as cefotetan and cefotaxime, or carbapenems, such as imipenem or meropenem. Another effective treatment against ESBLs is Clavulanic acid which can be used in combination with the above antibiotics for the treatment of urinary tract infections.

Should I take any precautions if I have had a previous ESBL infection?

There are no precautions or lifestyle changes to make if you have been previously infected with an ESBL other than following good basic hygiene. Once the infection has been cleared there is no risk to friends or relatives and you do not posses a higher risk of getting another infection. If you do get another infection it is important to let your healthcare team and doctor know that you have had an ESBL infection before so that they prescribe the appropriate treatment for you.

If I am in hospital with ESBL infection can I have visitors?

Visitors can come to the hospital but it is important that they take appropriate precautions and ensure that they wash their hands before and after visiting and do not sit on your bed. They do not need to wear aprons or gloves like nurses who usually get closer to the infection and have more exposure. It is best to limit the number of visitors to two at a time and also any visitors that are ill, elderly or very young should avoid visiting you until your infection has cleared.

Do I need to stay in hospital if I am infected with ESBLs ?

You can go home once you are feeling better even if you are still ESBL positive. You just need to ensure that you stick to hygiene precautions and advice provided by your nursing team and hospital.

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