WHO Antibiotic Categorization
  • Provides recommendations for 21 common infective diseases
  • Differentiates in three groups to minimize resistance
  • Identifies antibiotics that are priorities for monitoring and use surveillance

The clock is ticking

Most medicines remain effective even if used by many people for prolonged periods. Unfortunately, antibiotics are an important exception as they can become ineffective because of anti-microbial resistance

Anti-microbal resistance

Antibiotic resistance refers to the ability of microorganisms to withstand the effects of an antibiotic.
Bacteria are said to develop resistance when they are no longer inhibited or killed by the antibiotics.

Inappropriate use of antibiotics favors the emergence and spread of antibiotic resistance, amplifying natural ability of bacteria to resist.

Antibiotic vs. Bacteria

Patients and doctors, and bacteria are in a situation where the parties face some form of threat from the other parties: antibiotics are our cures, but bacteria are developing new strategies to resolve the confrontation. Recently the bacteria seem to gain an advantage having turned down some key antibiotics. So, antibiotic options are decreasing and, in some cases, we simply do not have more options.

Important

In order to keep antibiotics effective, we need to take them only when needed and strictly as directed by the doctor

Furthermore, there is a need to select the right antibiotic for a given infection when they are needed, privileging those antibiotics that offer the best therapeutic advantage minimizing the risk of resistance

The aim of the WHO AWaRe Antibiotic Categorization is to build a safe way to use antibiotics.

WHO

Antibiotic Categorization

To address these issues, WHO developed a framework based on three different categories – Access, WAtch and Reserve – which all together forms the AWaRe categorization of antibiotics.
access group
  • first or second choice antibiotics
  • offer the best therapeutic value, while minimizing the potential for resistance
watch group
  • first or second choice antibiotics
  • only indicated for specific, limited number of infective syndromes
  • more prone to be a target of antibiotic resistance and thus prioritized as targets of stewardship programs and monitoring
reserve group
  • “last resort”
  • highly selected patients (life-threatening infections due to multi-drug resistant bacteria)
  • closely monitored and prioritized as targets of stewardship programs to ensure their continued effectiveness
All groups: sufficient supplies should exist worldwide
others
  • not all antibiotics were included in the AWaRe framework, some of the antibiotics in this group may be included in future editions of the AWaRe classification
  • some high-priority bacterial infections (such as tuberculosis) and parasitic infections (such as malaria) are addressed by other WHO guidelines
How the antibiotic groups are assembled and how antibiotic selection ensures the best health outcomes?
The AWaRe categorization illustrates which are the preferred antibiotic options for each syndrome, balancing benefits, harms and the potential for resistance.
In 2017 WHO reviewed twenty one common infective syndromes, and selected the most appropriate first and second-choice antibiotic choices for each of the syndrome. The antibiotics were categorized following the AWaRe principles. However, to better understand how the antibiotics were divided into groups, three infective syndromes are used as explanatory examples below.
Explanatory examples
Ear infection
First line treatment
First choice
Second choice
No antibiotic therapy
access
e.g. Amoxicillin
access
e.g. Amoxicillin + clavulanic acid
Sore throat
First line treatment
First choice
Second choice
No antibiotic therapy
access
e.g. Amoxicillin
watch
e.g. Clarithromycin
Kidney infection
First line treatment
First choice
Second choice
Antibiotic therapy
watch
e.g. Ciprofloxacin
watch
e.g. Cefotaxime

You may want to ask:

What does “watchful observation” mean?
Sore throat was experienced by virtually everybody. From your own experience, you know that it often can be cured without help of antibiotics. In fact, most times it is caused by viruses, against which antibiotics do not work. For these reasons, the recommended first-line treatment for pharyngitis is watchful waiting. The problem starts to get better soon after is diagnosed in the large majority of cases.
Why it is important to not use antibiotics as first-line treatment in conditions such as ear infections or sore throat?
Not using antibiotics in such cases may help fight antibiotic resistance. There is an increasing collective recognition that antibiotics use should be scrutinized weighting pros and cons. Among cons adverse events and resistance are becoming prominent. When used with parsimony, antibiotics will stay effective to be uses for more serious cases and in people with weaker immune systems, e.g. infants or seniors.
What is the difference between first and second choices?
The first choice simply represents the best option in terms of effectiveness, harms and potential for resistance. In some cases, a second-choice antibiotic is also recommended. These antibiotics represent alternative options under some circumstances: they tend to be generally broader-spectrum antibiotics with higher resistance potential or less favorable risk–benefit ratios. Both first and second choices have specific indications (i.e. disease) for which they have been recommended.
What does it mean that the impact of antibiotics on different diseases is associated with different balance of benefits and harms??
Take the two examples we have shown above. Most cases of ear infections in children resolve spontaneously. Often, they are caused by viruses, but antibiotics are not effective against viruses. Antibiotics provide a small reduction in pain beyond 24 hours in only an absolute minority (about 5%) of children treated. This also means that 95% of children treated with antibiotic will have no relevant benefit associated with. The modest benefit must be weighed against the potential harms related to antibiotic use, both for the individual patient (e.g. allergic reactions and other side effects like diarrhea that will afflict one in every five patients treated). Furthermore, antibiotics also kill “good” bystander organisms on which we depend with unclear long-term consequences). Resistance comes on top of these harms. Kidney infections require prompt medical attention. If not treated properly, a kidney infection can permanently damage your kidneys or the bacteria infection can spread to your bloodstream and put your life at risk. For this reason, it is important that a kidney infection is timely treated with effective antibiotics. For these infections the benefits associated with antibiotic treatment largely outweigh the side effects. However, an increasing number of people diagnosed with pyelonephritis had infections resistant to the standard class of antibiotic used in treatment – fluoroquinolone - severely limiting antibiotic treatment options.
Why some of the antibiotics in the table above marked with two triangles?
These are antibiotics are in the WATCH group, which should be monitored by health authorities to prevent spread and further emergence of antibiotic resistance. We would prefer to use them for the diseases for which they are indicatedas little as possible, but sometimes it is necessary. This is not to use them as little as possible, but when it is necessary. For example, no ACCESS group antibiotic is able to treat serious infections that spread to the kidneys. This is one more reason to keep them effective, by not overusing them for conditions for which we have other options.
Is it possible that a WATCH (two triangles) antibiotic is a first choice, followed by an ACCESS (one triangle)?
Yes, this is true for example for meningitis, a very severe disease. This is due to the fact that aAntibiotics have different profiles in terms of effectiveness, safety, and resistance depending of the disease we consider. So it is possible that the same antibiotic that is in the WATCH group and a second choice for a diseases becomes a first choice for another disease. The inter-play between a disease and these dimensions might deeply alter the role of antibiotics across different diseases.
Are the WATCH (two triangles) antibiotics stronger?
No. Classifying an antibiotic to WATCH group has a lot to do with its susceptibility of being a target of monitoring activities by health authorities and potential for antibiotic resistance. Indeed, some of the antibiotics in the ACCESS group remain the “strongest”, most effective antibiotics for many infections.
Are there differences in how antibiotics from the different groups are administered?
100%
80%
60%
40%
20%
0%
access watch reserve
Without oral formulation
Oral formulation available
Generally, antibiotics in ACCESS group are more often available as oral formulations (nearly 60% of them), while this percentage is lower in the two other groups. 40% of WATCH antibiotics have oral formulations; the number is only 10% in the RESERVE group.
WHO orchestrates collection of data on the spread of antimicrobial resistance (through the GLASS - Global Antimicrobial Resistance Surveillance System) and effectiveness of antibiotic stewardship programs. These findings will be presented here as soon as the data is available.