CHEM OSENSORS Review Advances in Antimicrobial Resistance Monitoring Using Sensors and Biosensors: A Review Eduardo C. Reynoso 1 , Serena Laschi 2 , Ilaria Palchetti 3, * and Eduardo Torres 1,4   Citation: Reynoso, E.C.; Laschi, S.; Palchetti, I.; Torres, E. Advances in Antimicrobial Resistance Monitoring Using Sensors and Biosensors: A Review. Chemosensors 2021, 9, 232. https://doi.org/10.3390/ chemosensors9080232 Academic Editor: Philip Gardiner Received: 5 July 2021 Accepted: 16 August 2021 Published: 19 August 2021 Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affil- iations. Copyright: © 2021 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). 1 Ciencias Ambientales, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Puebla 72570, Mexico; eduardoc.reynoso@gmail.com (E.C.R.); eduardo.torres@correo.buap.mx (E.T.) 2 Nanobiosens Join Lab, Università degli Studi di Firenze, Viale Pieraccini 6, 50139 Firenze, Italy; serena.laschi@gmail.com 3 Dipartimento di Chimica, Università degli Studi di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy 4 Centro de Quìmica, Benemérita Universidad Autónoma de Puebla, Puebla 72570, Mexico * Correspondence: ilaria.palchetti@unifi.it Abstract: The indiscriminate use and mismanagement of antibiotics over the last eight decades have led to one of the main challenges humanity will have to face in the next twenty years in terms of public health and economy, i.e., antimicrobial resistance. One of the key approaches to tackling an- timicrobial resistance is clinical, livestock, and environmental surveillance applying methods capable of effectively identifying antimicrobial non-susceptibility as well as genes that promote resistance. Current clinical laboratory practices involve conventional culture-based antibiotic susceptibility testing (AST) methods, taking over 24 h to find out which medication should be prescribed to treat the infection. Although there are techniques that provide rapid resistance detection, it is necessary to have new tools that are easy to operate, are robust, sensitive, specific, and inexpensive. Chemical sensors and biosensors are devices that could have the necessary characteristics for the rapid diag- nosis of resistant microorganisms and could provide crucial information on the choice of antibiotic (or other antimicrobial medicines) to be administered. This review provides an overview on novel biosensing strategies for the phenotypic and genotypic determination of antimicrobial resistance and a perspective on the use of these tools in modern health-care and environmental surveillance. Keywords: antimicrobial resistance; sensor; biosensor; antibiotic susceptibility test; phenotypic technique; genotypic technique 1. Antimicrobial Resistance In recent years, antimicrobial resistance (AMR) has received a great deal of attention because of the impact resistant microorganisms have on public health. Consequently, it has been declared as a global public health concern [1–7]. According to the World Health Organization (WHO), antimicrobial resistance occurs when bacteria adapt and grow in the presence of an antimicrobial (AM) agent [8]. It can also be described as a phenomenon when microorganisms (bacteria, viruses, fungi, and parasites) are no longer affected by an AM to which it was previously sensitive, as a result of mutation of the microorganism to evade the effect of the antimicrobial or of the acquisition of the resistance gene [9,10]. It is estimated that by 2050, human deaths related to AMR will amount to 10 million, resulting in an economic cost of about 100 billion dollars [11]. Although, there is compelling economic justification for the development of new generations of antibiotics by 2030 [12], the acquisition rate of biological resistance to new drugs is now a major consideration in preventing their introduction [7,13,14]. The WHO has established a list of antimicrobials (limited to antibiotics) that are important in human medicine and in veterinary practice. The top priority antimicrobials are cephalosporins (3rd, 4th, and 5th generation), glycopeptides, macrolides and ketolides, Chemosensors 2021, 9, 232. https://doi.org/10.3390/chemosensors9080232 https://www.mdpi.com/journal/chemosensors