Effectiveness of methods of control for external environment objects of health care institutions in relation to the causative agent of tuberculosis. Part 1 – The methods for detecting (isolating) and preparation

Introduction. Improving the efficiency of the method of washouts from environmental objects and sample preparation for the primary seeding of material for Mycobacterium tuberculosis (Mtb) during sanitary and bacteriological control is an urgent area of improvement of nonspecific tuberculosis prevention.

Materials and Methods. The studies (n=2500) included: suspension preparation Mtb H37Rv); preparation and contamination of test-objects (tile, glass, metal, plastic, painted surface); selection of tools for washouts (fine-pore foam, cotton swab, universal tampon probe), solution for washout (Dey-Engley broth, 5.0% Na₃PO₄, 0.9% NaCl), solution for decontamination (10.0% Na₃PO₄, NALC-NaOH); comparative of the efficacy of two methods for the isolation of Mtb (known method No.1 and modified method No.2).

Results. The efficiency of the method No. 2 (due to the use of: universal tampon probe; Dey-Engley broth; NALC-NaOH) significantly (p-value <0.001) exceeds the efficiency of method No. 1 (fine-pore foam, 5.0% and 10.0% Na₃PO₄ solutions) by 48.0 times at the concentration of Mtb in the solution of washout at 10³ CFU/ml, by 22.3 times – at the concentration of 10⁴ CFU/ml, by 8.0 times – at 10⁵ CFU/ml and by 4.6 times – at 10⁶ CFU/ml.

Limitation. The modified method allows obtaining growth of CFU of Mtb on Levenshtein-Jensen at the concentration of Mtb in the solution of washout at 10³ CFU/ml.

Conclusions. High efficiency of the developed method of Mtb isolation from the objects of external environment (exceeding by 48 times the results obtained by the standard method) during sanitary and bacteriological control, reduction both of labor costs and the of time for research, standardization of the method in terms of exclusion of tools prepared by “manual” method; use of Dey-Engley broth, positively affecting the viability of Mtb; reduction of decontamination time from 18–24 hours to 40–45 min – allow considering the presented method as a promising one for inclusion in the list of methods of sanitary and bacteriological control in relation to Mtb.

Compliance with ethical standards. The study did not require ethical committee approval (no studies using animals or involving humans).

Contribution:
Eremeeva N.I. – concept and design of the study, collection of material and data processing, writing, editing, approval of the final version of the article, responsibility for the integrity of all parts of the article;
Trukhina G.M. – research concept and design, text writing, editing, and approval of the final version of the article.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version.

Conflict of interest. The authors declare no conflict of interest.

Funding. The study was carried out within the framework of research works: No. NIOCTR 121022600261-1 “Biological properties of clinical isolates of Mycobacterium tuberculosis resistant to antibacterial and biocidal drugs”; No. NIOCTR 1023032900360-9-1.6.2 “Development of new methodologies for assessing the effectiveness of physical, chemical and combined methods of disinfection and sterilization”.

Received: April 20, 2025 / Revised: July 6, 2025 / Accepted: September 19, 2025 / Published: October 20, 2025

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