COMPARATIVE SUSCEPTIBILITY PROFILES OF CLINICAL AND REFERENCE BACTERIAL STRAINS ACROSS MULTIPLE ANTIBIOTIC CLASSES

Area of Science:

• Microbiology
• Infectious Diseases
• Public Health

Background:

• Antimicrobial resistance (AMR) is a critical global health challenge, compromising antibiotic effectiveness.
• Resistance mechanisms and prevalence vary significantly across different bacterial groups, including Enterobacteriaceae, Gram-negative non-fermenters, and Gram-positive cocci.

Purpose of the Study:

• To conduct a comparative analysis of antimicrobial susceptibility between reference strains and clinical isolates.
• To evaluate the stability of phenotypic resistance traits in reference strains and assess the influence of antibiotic usage patterns on susceptibility.

Main Methods:

• Antimicrobial susceptibility testing was performed on reference strains with known susceptible and resistant phenotypes and selected clinical isolates.
• Bacterial taxa analyzed included Enterobacteriaceae, Pseudomonas aeruginosa, Acinetobacter baumannii, and Gram-positive cocci.

Main Results:

• Reference strains showed high susceptibility, while resistant strains exhibited multidrug resistance. Specific resistance mechanisms like ESBL and AmpC were observed in Enterobacteriaceae.
• Non-fermenters displayed intrinsic and acquired resistance, particularly to carbapenems and fluoroquinolones. Gram-positive cocci generally remained susceptible to glycopeptides and linezolid, with exceptions like MRSA and resistant Streptococcus pneumoniae.
• Clinical isolates, such as Klebsiella pneumoniae and Streptococcus pneumoniae, demonstrated reduced and more variable susceptibility compared to reference strains, indicating the impact of antibiotic use.

Conclusions:

• Bacterial taxonomy and antibiotic use patterns are key determinants of antimicrobial susceptibility.
• Continuous surveillance, robust antimicrobial stewardship, and the use of standardized reference strains are crucial for accurate susceptibility testing.
• Early identification of emerging resistance is vital for effective treatment and mitigating the spread of multidrug-resistant pathogens.