Antimicrobial Resistance (AMR) has become a concerning public health issue that threatens people’s well-being. The WHO predicts that by 2050, deaths attributable to infectious diseases caused by antimicrobial-resistant bacteria will exceed 10 million per year, highlighting the urgency for society as a whole to address this health crisis. In this context, establishing Antimicrobial Stewardship Programs (ASP), both in hospitals and in the community, becomes essential. One of the fundamental pillars of these programs is the reformulation of recommendations for the use of antibiotics in empirical treatment of the most common infections—both in the community and in hospitals—based on evidence from local epidemiology and susceptibility patterns, as well as antibiotic resistance. This is where the antibiogram (in vitro analysis and study of microorganisms’ response to antimicrobial agents) plays a key role.

The antibiogram is a highly valuable methodology used in traditional clinical microbiology. Its purpose is clear and vital: it determines the susceptibility and/or resistance profile of bacteria and fungi to a specific group of antibiotics or antifungals, as recommended by internationally recognized expert organizations and committees. This information is crucial not only for selecting the most appropriate antibiotic treatment for each specific infection, but also for reducing unnecessary and inappropriate use of broad-spectrum antibiotics. Doing so not only decreases the likelihood of selecting resistant bacterial populations, but also helps reduce complications derived from Healthcare-Associated Infections (HAIs), especially in hospital settings.

In a world where bacteria are developing immunity to treatments, understanding the antibiogram becomes an urgent necessity. It is not just a simple reading of susceptibility or resistance; it is a process that requires deep interpretation of the potentially present bacterial resistance mechanisms, as well as knowledge of the pharmacokinetics and pharmacodynamics of antimicrobial agents—not to mention potential treatment-related adverse effects. These are essential concepts and form part of the strategies and interventions required to confront and slow this growing problem.

The process of performing an antibiogram in clinical laboratories begins with obtaining a biological sample for culture, which can include blood, urine, respiratory secretions, abscesses, or bodily fluids. A fundamental aspect is the quality of the sample. A poorly collected, transported, or preserved sample can result in inaccurate microbiological diagnoses, which in turn may lead to inappropriate treatments and further aggravation of the Antimicrobial Resistance problem.

Interpretation of antibiogram results is based on breakpoints established by international organizations such as CLSI (Clinical and Laboratory Standards Institute) or EUCAST (European Committee on Antimicrobial Susceptibility Testing). In the case of severe infections such as sepsis, meningitis, or endocarditis, choosing the correct antibiotic can mean the difference between life, death, and potential complications. In immunocompromised, oncology, or transplant patients, this choice becomes even more critical, underscoring the importance of performing an antibiogram in clinical practice.

The development of Rapid Diagnostic Technologies (RDTs) has made the outlook more promising. These innovations allow Antimicrobial Stewardship Programs (ASP) to recommend targeted antibiotic therapies, significantly improving clinical outcomes. Many clinical laboratories now use RDTs to detect antibiotic resistance genes, adding an extra layer of usefulness to the traditional antibiogram. By incorporating information on resistance markers, empirical antibiotic therapy can be optimized, allowing rapid and effective responses to the patient’s needs.

Syndromic molecular diagnosis has taken a major leap in this field of antimicrobial resistance, enabling faster and more accurate detection of the most common enzymatic resistance mechanisms. While traditional phenotypic methods rely on bacterial growth rates over time (18 to 24 hours) when tested against antibiotics, molecular techniques identify the specific genes responsible for resistance directly from the sample in an average time of one hour. This information is not only crucial for treatment but also provides a proactive approach in the fight against AMR.

The battle against Antimicrobial Resistance is a shared responsibility of society at large and the medical community. Every healthcare professional, every laboratory, and every patient has a role to play. As we move toward an uncertain future where resistant bacteria may become the norm, the antibiogram stands as an essential tool to guide us through this uncertainty. Now more than ever, we need to join efforts, promote research, and educate on the rational and optimal use of antibiotics.