Resistance of representatives of the order Enterobacterales to ertapenem 12.1%. The highest frequency of insensitivity to this antimicrobial drug was noted among isolates of K. pneumoniae 29.4%. Among all enterobacterial isolates, resistance to imipenem and meropenem was 17.2% and 20%. The proportion of P. aeruginosa strains is 50.9% resistant to meropenem and imipenem, respectively, and 45% to doripenem. In turn, A. baumannii is resistant to meropenem - 66.6%, imipenem - 63.6%, doripenem - 83.3%. The following resistance genes were found in K. pneumoniae: NDM (n=2), KPC (n=10), OXA (n=1); in P. aeruginosa: VIM (n=8), NDM (n=1), OXA (n=1); A. baumannii OXA (n=1). At present, it is optimal to use molecular methods, in particular real-time PCR, to effectively monitor the distribution of carbapenemase producers, which tend to be widely distributed in a hospital setting. Molecular methods allow you to quickly get the result (during the working day) and give an adequate decision on antibiotic therapy.

Background: the steadily increasing occurrence of the infections caused by antibiotic-resistant germs and the reduction in the efficacy of antimicrobials is one of the important issues of modern medicine. Aim: to study the colonization of rectal mucosa by extended-spectrum beta-lactamase (ESBL) — producing carbapenem-resistant Enterobacterales, carbapenem-resistant Pseudomonas aeruginosa, and vancomycin-resistant Enterococci using phenotypic methods and gene tests. Patients and Methods: this study was performed from December 10, 2019, to March 30, 2020. 150 samples (131 fecal specimens and 19 rectal swabs) collected from 66 patients who were admitted to the Hematological Center were examined. All samples were inoculated into selective chromogenic media. Results: 67 strains of Enterobacterales, 71 Enterococci, and 7 P. aeruginosa were isolated. Rectal colonization by ESBL-producing Enterobacterales was identified in 17 patients (25.8%). Е. coli (13 strains, 44,8%) and K. pneumoniae (10 strains, 34,5%) prevailed. In 5 children, two or more ESBL-producing strains were isolated, i.e., Е. coli plus K. pneumoniae (n=2), Е. coli plus E. cloacae (n=2), and Е. coli plus K. pneumoniae plus E. cloacae (n=1). The colonization by vancomycin-resistant Enterococci (predominantly E. faecium) was identified in 18 patients (27.3%). Vancomycin-resistant Enterococci plus ESBL-producing Enterobacterales were isolated in 9 patients (13.6%). Multidrugresistant strains were isolated among Е. coli (n=1), K. pneumoniae (n=3), and P. aeruginosa (n=1). Conclusions: our findings demonstrate that the colonization by one and two antibiotic-resistant microbe was seen in every forth patient (25.8– 27.3%) and every seventh patient (13.6%), respectively. Е. coli and K. pneumoniae prevailed among Enterobacterales and E. faecium prevailed among Enterococci. Chromogenic agars are designed to examine the specimens collected from patients. Antibiotic-resistant microbes may be identified 24 hours after receiving specimen at a laboratory when using these media. KEYWORDS: monitoring, colonization, resistance marker, microorganisms, children, hematological malignancies. FOR CITATION: Boronina L.G., Samatova E.V., Kukushkina M.P. et al. Colonization of rectal mucosa by microbes with antibiotic resistance markers in children with hematological malignancies. Russian Journal of Woman and Child Health. 2021;4(1):90–97. DOI: 10.32364/2618- 8430-2021-4-1-90-97.

The quality of culture media for blood culture was checked: nutrient medium for children with an antibiotic neutralizer for the cultivation of aerobes, nutrient medium with an antibiotic neutralizer for the cultivation of anaerobes, a nutrient medium with an antibiotic neutralizer for the cultivation of aerobes, nutrient medium for the cultivation of aerobes UNONA® used in the automatic bacteriological analyzer JUNONA ®Labstar 50 (SCENKER Biological Technology Co., Ltd. China). Used tenfold dilutions from 18-24 hour cultures of reference strains: ATCC 13124 Clostridium perfringens; ATCC 25285 Bacteroides fragilis; NCTC 194I8 Haemophilus influenzae; ATCC 49619 Streptococcus pneumoniae; ATCC 16615 Streptococcus pyogenes; ATCC 27853 Pseudomonas aeruginosa; ATCC 25923 Staphylococcus aureus; ATCC 25922 Escherichia coli; BKPGU-401/-885-653 Candida albicans; ATCC13813 Streptococcus agalactiae; No. 186 Enterobacter cloacae; ATCC 29212 Enterococcus faecalis; clinical isolates: Acinetobacter lwofii, Enterobacter cloacae, Candida tropicalis. All investigated reference strains were isolated on nutrient media in accordance with their biological properties when inoculated with 50 CFU / ml less than 72 hours later, as stated by the manufacturer. The study has shown that growth factors must be used to test the quality of the culture media with Haemophilus influenzae bacteria and this must be reflected in the manufacturer’s instructions.

Primarily in the study of bacteremia, coagulase-negative staphylococci and representatives of the order Enterobacterales were found. To establish the etiological role of coagulase-negative staphylococcus in making a diagnosis of sepsis in each particular case, it is necessary to consider the condition and age of the child, as well as indicators of markers of systemic inflammation. In 1/3 cases of coagulase-negative staphylococcus indicate colonization of the catheter. Staphylococcus aureus in bacteremia and sepsis - 6.5%, Haemophilus influenzae - 0.6%, Esherichia coli - 7.8%, Streptococcus agalactiae - 2%. For the diagnosis of sepsis, it is necessary to conduct repeated (at least two times) blood culture studies using high-quality nutrient media containing all the necessary growth factors, followed by a mandatory determination of the susceptibility of the isolated strains of microorganisms to antimicrobial agents. Bacteremia as a whole in children of a multidisciplinary hospital amounted to 5.8%. In premature babies, bacteremia was detected in 4.4% of cases, of which sepsis was confirmed in 41,2%.

Aim. To evaluate the feasibility of an accelerated method for determining the etiology of infections in urine, dialysate and residual antimicrobial activity by using laser light scattering technology.Materials and methods. From January to September 2019, 106 urine samples and 42 dialysate samples from children aged 1–16 with various urinary pathologies and those on peritoneal dialysis underwent culture-based examination on an ALIFAX HB&L LIGHT analyzer (Alifax, Italy) using laser light scattering technology.Results. Three hours after inoculation, 81 samples (76.4%) appeared to be negative and 25 samples (23.6%) proved to be positive. No microorganisms were detected in 38 dialysate samples (90.5%), two samples had Staphylococcus aureus (104 CFU/ml), and one dialysate sample had Corynebacterium sp. and associations of Escherichia coli + Candida albicans + Staphylococcus haemolyticus, associated with peritoneal catheter colonization. Bacteriuria was caused by Enterobacterales in 39.3% (E. coli, Morganella morganii, Citrobacter amalonaticus, Enterobacter cloacae), non-fermenting gram-negative bacteria – in 14.3% (Pseudomonas aeruginosa, Ralstonia picketii, Oligella sp., Acinetobacter baumannii), Enterococcus sp. – 21.4%, S. haemolyticus, Staphylococcus epidermidis – 10.7%, Candida albicans – 3.6%, contamination: Streptococcus viridians, Corynebacterium sp. – 7.1%. Residual antimicrobial activity in urine was detected in 30.1% of patients.Conclusion. The laser light scattering technology enables a minimal concentration of microorganisms to be detected in a smaller amount of urine or dialysate, which is very important for accelerated diagnosis of urinary tract infections and complications of peritoneal dialysis in children.