Objective: To evaluate the state of beta-lactamase activity (BLA) in biological fluids in patients with infectious exacerbation of respiratory pathology.

Methods and Materials: The level of BLA of blood serum was determined in 95 patients with exacerbation of COPD (55 patients) and community-acquired pneumonia (40 patients) using the "BioLactam" test system (BLR) on the background of comprehensive clinical and laboratory and instrumental examination, characterizing the severity of the disease course.

Outcomes. The level of blood serum BLA is determined by phenotypic and clinical variables such as age over 60 y, severe respiratory pathology, temperature elevation above 38.0°C, peripheral blood leukocyte count above 10x109/L, C-reactive protein greater than 40 mg/L, and saturation less than 93%, which are correlated with increased BLA levels and predict low efficacy of BLAs treatment. A direct correlation was found between the level of blood serum BLA and the duration of antimicrobial therapy within a year (r=+0.86, p=0.001), the number of AMPs concurrently prescribed (r=+0.69, p=0.001), receipt of beta-lactam reserve antibiotics such as cefepime, imipenem, meropenem (r=+0.71, p=0.001), and prescription of non-beta-lactam reserve antibiotics such as rifampin, azithromycin, vankomycin, linezolid, levofloxacin (r=+0.59, p=0.001). 

Conclusion: The conclusion argues for the necessity of determining the level of beta-lactamase activity in biological substrates in order to predict the efficacy of successful treatment with first-line BLA within the framework of evidence-based medicine. The evaluation of the BLA level will allow for a reduction of up to 30% in the unjustified use of BLAs.