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Mechanisms of resistance in the Klebsiella pneumoniae, Pseudomonas aeruginosa, Acinetobacter baumannii strains isolated from blood and cerebrospinal fluid of children.
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1  National Medical Research Center for Children's Health Federal State Autonomous Institution of the Ministry of Health of the Russian Federation (registering DOI)

The main problem in the treatment of nosocomial infections is spreading of gram-negative carbapenem-resistant microorganisms. Therefore, it is important to monitor the sensitivity of nosocomial infections to antibiotics from the carbapenem group and to determine the mechanisms of the microorganisms resistance.

Methods: During the period from 2014 to 2020, 98 strains isolated from blood and cerebrospinal fluid of the children in intensive care units were selected. Antibiotic sensitivity was determined by broth microdilution. Strains of P. aeruginosa with a minimum inhibitory concentration of meropenem> 2 mg / L and / or imipenem> 0.001 mg / L, in K. pneumoniae and A. baumannii, meropenem> 2 mg / L and / or imipenem> 2 mg / L, other strains were classified as susceptible to carbapenems. Carbapenemases were detected by real-time multiplex polymerase chain reaction (PCR).

Results: Among the studied strains there were 62 (63%) K. pneumoniae strains, 22 (23%) P. aeruginosa strains and 14 (14%) A. baumannii strains. Among all isolates of K. pneumoniae, 28 (45%) were classified as resistant to carbapenems, the other 34 (55%) strains were classified as susceptible. Among the studied strains of P. aeruginosa, 16 (73%) were insensitive to carbapenems, and 6 (27%) isolates were susceptible. Of the A. baumannii strains studied, 10 (71%) were in the carbapenem-insensitive group and 4 (29%) were in the carbapenem-susceptible group.

In the process of studying the mechanisms of resistance to carbapenems, the following results were obtained. In K. pneumoniae isolates, the cause of resistance to carbapenems was blaOXA-48 carriage (n = 25, 89%). The presence of blaNDM and blaKPC was not identified. 11 (69%) P. aeruginosa isolates had blaVIM. The A. baumannii strains had carbapenemase OXA-40 (n = 5, 50%) and OXA-23 (n = 3, 30%).

Conclusions: In most cases, resistance to carbapenem antibiotics in the studied strains isolated from blood and cerebrospinal fluid of children in intensive care units was due to the presence of various carbapenemases. For K. pneumoniae, OXA-48 was the only determinant of resistance. P. aeruginosa resistance was associated with VIM group carbapenemases. The A. baumannii strains contained carbapenemases OXA-40 and OXA-23.

Keywords: Mechanisms of resistance, nosocomial infections