What is ESBL?
Multi-drug Resistant Bacteria that Cause Nosocomial Infections
You may have heard of the superbug MRSA, and you might even be familiar with the diarrhea bug C. diff, but if you've visited a hospital lately, you might hear a new term flung around: ESBL. Even some nurses are scratching their heads. Just what is this new bad boy?
Extended-Spectrum Beta Lactamase
ESBL stands for “extended-spectrum beta lactamase.” ESBL bacteria are different from other superbugs, because “ESBL” does not refer to one specific kind of bacteria. (For instance, MRSA refers specifically to methicillin-resistant strains of S. aureus.) Instead, it refers to an antibiotic-busting enzyme that many different kinds of bacteria can produce.
ESBL's history starts, as many histories do, with a war: The war between us and the bacteria. When we discovered the first antibiotics (quite by accident, incidentally), it was as if we had created medicine's own atomic bomb. These antibiotics were called penicillins, after the organism they were isolated from.
The devilishly clever bacteria met our challenge by creating beta lactamase, an enzyme that grants many bacteria immunity to penicillin-type antibiotics. In turn, we upped the ante by developing new kinds of antibiotics that trounced these beta lactamase-producing pathogens.
But the bacteria weren't done yet. Some tricky little bugs had a trick up their metaphorical sleeves: Beta Lactamase model 2.0, known to us as extended-spectrum beta lactamase, or ESBL. This enzyme not only chops apart penicillins, but cephalosporin antibiotics, too (all of the antibiotics whose generic names begin with “Cef-”).
Why is This Hospital-Acquired Infection a Threat?
ESBL bacteria stand apart from other strains of bacteria only because they are immune to some kinds of antibiotics. Otherwise, they do what other bacteria of their species normally do – including causing the same diseases. Disease caused by ESBL organisms is no more acute than the disease caused by another bacteria of the same type. However, due to their immunity to some antibiotics, they can be trickier and more difficult to treat. This leads to longer hospital stays, rising healthcare costs, and increased mortality rates.
Many different species of bacteria can produce the ESBL enzyme, including both gram positive and gram negative bacteria. The most common ESBL bacteria are E. coli and Klebsiella species. Both can be indicated in surgical site infections and blood infections, and are commonly responsible for urinary tract infections (UTIs).
Diagnosing and Treating ESBL with Antibiotics
ESBL organisms can be tricky to diagnose and treat. According to the Centers for Disease Control (CDC), some ESBL organisms cannot be detected using standard laboratory methods, producing false-negative results.
Once ESBL has been detected, the bacteria must be tested for antibiotic sensitivity. Different strains of ESBL can be immune to different antibiotics, so each individual sample of ESBL is tested in the lab to discover with antibiotics it is susceptible to. This is called a “sensitivity” test. With this test, the physician can order an appropriate antibiotic for the patient. Unfortunately, antibiotics that kill bacteria in vitro (in the lab) may be useless when administered to a live human being, given that the human body is much more complex than a petri dish.
Using Contact Precautions to Prevent the Spread of ESBL Healthcare-Associated Infections
So, if it is difficult to detect and difficult to treat, what can we do about ESBL?
We can prevent its spread.
Preventing the spread of nosocomial infections like ESBL is our #1 defense against them. Without a route of transmission, the bacteria cannot travel to new hosts and make more people sick.
ESBL bacteria are spread through contact, often by the hands of healthcare workers. Less frequently, they may spread from one patient directly to another, or by visitors. Ironically, the number one method of infection prevention is very simple: hand washing. According to a study dating back to 1977, washing the hands with antimicrobial soap reduced 98% - 100% of Klebsiella they harbored.
In the hospital, patients with ESBL organisms are placed on “contact precautions.” This often means that the patients may have a private room to prevent spread of the disease to a roommate. It also means nurses and other healthcare personnel must wash their hands and don gloves when working with these patients, and they might wear a plastic gown to protect their clothing. Medical equipment is dedicated to the patient with ESBL to prevent the spread of bacteria on stethoscopes, thermometers, and blood pressure machines. The patient might or might not be isolated to his or her room.
As a healthcare provider, remember to wash your hands, even if you wear gloves. When a patient is placed on contact precautions, use only disposable and dedicated medical equipment for the patient when possible. Remember to use appropriate personal protective equipment, such as an isolation gown.
As a patient, kindly remind your nurses, aides, doctors, and other hospital employees that come in contact with you to wash their hands. Also, wash your own hands before eating or touching your face (and, of course, after using the restroom).
Washing hands, #1 method to prevent ESBL spread
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