Carriage of K. pneumoniae and molecular structure of produced carbapenemases in infants with congenital heart defects
Authors: Popov Dmitriy A. , Osokina R. A. , Vostrikova T. Yu. 
Published: September 2023

Objective.
To evaluate frequency of pharyngeal and rectal mucosa colonization by K. pneumoniae strains in infants with congenital heart defects at the stage of cardiosurgical hospital admission, as well as dynamic analysis of production frequency and molecular structure of K. pneumoniae carbapenemases.

Materials and Methods.
A total of 1445 patients with risk factors (antibiotic therapy in the anamnesis, emergency hospitalization, transfer from other hospitals) admitted for surgical treatment of congenital heart defects (CHDs) between January 1, 2020 and December 31, 2022 were included in the retrospective analysis. Median age was 1.08 months (between 0 and 12 months). Smears from the pharyngeal and rectal mucosa (2890 samples) were taken for microbiological examination no later than 72 h after admission. The isolation of extended-spectrum beta-lactamases (ESBLs) and/or carbapenemases producing K. pneumoniae in the absence of symptomatic infection was considered as colonization. K. pneumoniae strains were considered as «problematic» in the absence of susceptibility to three or more groups of antimicrobials: the third- and fourth-generation cephalosporins, carbapenems, fluoroquinolones, aminoglycosides. The profile of antibiotic resistance, carbapenemases production and their molecular type were determined in the isolated strains.

Results.
K. pneumoniae carriage with «problematic» sensitivity was detected in 252 out of 1445 (17.4%) patients: 153 out of 1445 (10.6%) children were colonized by only ESBLs producers, and 99 out of 1445 (6.9%) children – by both ESBLs and carbapenemases producers. In dynamics, the number of ESBLs producers carriers decreased by 1.5 times (50 out of 448 – 11.2% and 37 out of 506 – 7.3% in 2020 and 2022, respectively). The number of K. pneumoniae producing both ESBLs and carbapenemases carriers increased by 4.9 times (11 out of 448 – 2.5% and 62 out og\f 506 – 12.3% in 2020 and 2022, respectively), in 2022 exceeding the proportion of only ESBLs producers carriers by 1.7 times. The molecular structure of carbapenemases was represented by OXA-48 carbapenemases (44 out of 99 – 44.5%), NDM metalloenzymes (35 out of 99 – 35.4%), OXA-48 and NDM combinations (13 out of 99 – 13.1%), KPC (3 out of 99 – 3%), NDM, KPC and OXA-48, NDM and KPC combinations: 3 out of 99 – 3% and 1 out of 99 – 1% of carriers, respectively. In dynamics, the number of isolates with the production of OXA-48 carbapenemases increased by 34.8% (from 18.2% to 53% in 2020 and 2022, respectively), NDM carbapenemases and co-producers of OXA-48, NDM decreased by 25.9% (from 54.5% to 28.6% in 2020 and 2022) and 19.1% (from 27.3% to 8.2% in 2020 and in 2022), respectively. In 2022, strains with the production of KPC carbapenemases and co-producers of carbapenemases of three classes (OXA-48, NDM and KPC) were identified for the first time.

Conclusions.
The data obtained indicate an increase in the frequency of initial colonization of patients with carbapenem-resistant K. pneumoniae, an expansion of the structure of carbapenemases produced by them, that, if infection control measures are not followed, can increase the frequency of infections caused by them.