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.

Aim: to define the incidence of carbapenem-resistant Enterobacteriaceae in the bioassay of hospitalized children. Patients and Methods: From January to December 2019, 940 strains of gram-negative bacteria were isolated from clinical material of 900 patients. Antibiotic susceptibility testing was conducted using the disk diffusion method; SENSITITRE and Phoenix M50 analyzers used «CHROMagarTM KPC» medium. Also, Carbapenem Inactivation Method was used to detect the carbapenemase activity. Results: the species composition of carbapenem-resistant Enterobacteriaceae included: Pseudomonas aeruginosa (n=55), Acinnetobacter baumannii (n=22), Escherichia coli (n=2), Klebsiella pneumoniae (n=40), Klebsiella oxytoca (n=1), Enterobacter cloacae (n=7), Serratia marcescens (n=2), Proteus mirabilis (n=2), Pseudomonas putida (n=1). 12.1% of all Enterobacterales isolates and 29.4% Klebsiella pneumoniae strains were resistant to ertapenem; 17.2% of Enterobacteriaceae and 20% of K. pneumoniae strains were resistant to imipenem and meropenem. 50.9% of Pseudomonas aeruginosa strains were resistant to meropenem and imipenem, and 45% — to doripenem. Acinetobacter baumannii strains resistant to meropenem — 66.6%, imipenem — 63.6%, doripenem — 83.3%. In 30.4% of P. aeruginosa and A. baumannii strains, carbapenemase activity was not detected, which indicated other mechanisms of resistance to carbapenem. Conclusion: in most cases, phenotypic methods only allow to suspect the presence of certain mechanisms of acquired resistance. However, since the main, most common mechanism is the production of hydrolytic enzymes, the identification of mechanisms of resistance to carbapenems should be precisely directed at this. At present, in addition to phenotypic methods, it is optimal to use molecular methods, in particular, realtime PCR, to effectively monitor the distribution of carbapenemase producers. KEYWORDS: Enterobacterales, non-fermenting gram-negative bacteria, carbapenemases, children, infection. FOR CITATION: Boronina L.G., Samatova E.V., Blinova S.M. et al. Incidence of carbapenem-resistant Enterobacteriaceae in the multidisciplinary pediatric hospital. Russian Journal of Woman and Child Health. 2020;3(4):295–301. DOI: 10.32364/2618-8430-2020-3-4-295-301.