eChapter Name: Conventional Methods for Antimicrobial Resistance Detection: Principles, Applications, and Global Relevance
9789372197242
eBook Name: ONE HEALTH AND ANTIMICORBIAL RESISTANCE: CONFRONTING GLOBAL THREATS WITH LOCAL
Introduction
Antimicrobial resistance (AMR) poses an escalating threat to global health, eroding the efficacy of antibiotics and complicating the management of bacterial infections. The proliferation of resistant pathogens, such as methicillin-resistant Staphylococcus aureus (MRSA), extended-spectrum betalactamase (ESBL)-producing Enterobacteriaceae, and multidrug-resistant Mycobacterium tuberculosis, has driven significant increases in morbidity, mortality, and healthcare costs. The ability to detect AMR accurately and promptly is paramount for guiding clinicians in selecting effective therapies, implementing targeted infection control measures, and informing public health strategies to curb the spread of resistant organisms. Conventional methods, rooted in phenotypic assessments, have served as the cornerstone of AMR detection in clinical microbiology laboratories for decades. These techniques evaluate bacterial growth under controlled exposure to antibiotics, offering direct evidence of resistance or susceptibility that molecular approaches, which focus on genetic markers, may miss due to silent mutations, complex regulatory mechanisms, or novel resistance pathways. This chapter provides an exhaustive examination of conventional AMR detection methods, encompassing disk diffusion, broth and agar dilution, gradient diffusion, and automated susceptibility testing systems. These approaches, refined through decades of clinical and research application, remain indispensable for their reliability, cost-effectiveness, and adaptability across diverse settings, from well-resourced tertiary hospitals to laboratories in low-income regions. By exploring their principles, procedures, applications, and limitations, we aim to underscore their enduring significance amidst the rise of rapid molecular diagnostics. The discussion also addresses specialized tests for detecting specific resistance mechanisms, such as beta-lactamase production, inducible clindamycin resistance, and carbapenem’s activity, which are critical for tailoring antimicrobial therapy. Through a critical lens, this chapter evaluates the strengths and challenges of these methods, offering insights into their role in addressing the global AMR crisis, their integration with emerging technologies, and their continued relevance in both routine diagnostics and epidemiological surveillance. The value of conventional methods lies in their ability to translate laboratory findings into actionable clinical decisions. Unlike genotypic methods, which detect resistance genes but may not predict phenotypic behaviour, these techniques assess how bacteria respond to antibiotics under conditions mimicking in vivo environments, aligning closely with therapeutic outcomes. As resistance patterns grow increasingly complex, driven by mechanisms like carbapenem’s and efflux pumps, conventional methods provide a practical foundation for diagnostics, particularly in resource-limited settings where advanced molecular tools are often inaccessible. Their role in global AMR surveillance, such as through the World Health Organization’s Global Antimicrobial Resistance Surveillance System (GLASS), further underscores their importance in tracking resistance trends and informing policy.