In vitro analysis of combined phenotypic resistance of clinical isolates of Escherichia coli and Klebsiella pneumoniae to antibiotics and humoral factors of innate immunity

One of the serious challenges in modern medicine is the development of combined resistance in bacteria to antimicrobial agents and humoral factors of innate immunity. This phenotype not only limits the options for antimicrobial therapy but also enables pathogens to more effectively overcome the body’s first line of defense, leading to severe disseminated processes that are difficult to manage with standard treatment regimens.

The aim of this study was to assess in vitro the presence of combined phenotypic resistance in clinical Enterobacteriaceae isolates to antibiotics and humoral factors of innate immunity present in blood serum and plasma.

A total of 59 clinical isolates of Escherichia coli (n = 30) and Klebsiella pneumoniae (n = 29), collected from various hospitals in Minsk between 2021 and 2023, were analyzed. The antibiotic susceptibility testing was performed using the VITEK 2

Compact system. The resistance to the antimicrobial action of native serum, native plasma, and platelet-rich plasma (PRP) was evaluated using the broth microdilution method.

A high prevalence of combined resistance to exogenous and endogenous antimicrobial agents was observed in Gramnegative bacteria. Among clinical isolates of E. coli, resistance to penicillins, cephalosporins, fluoroquinolones, and sulfonamides was associated with resistance to blood serum in 60.0–66.7 % of cases. In contrast, K. pneumoniae isolates exhibited critically high resistance to carbapenems (72.4 %), protected penicillins (79.3 %), cephalosporins (82.1 %), and fluoroquinolones (82.8 %), with the majority of these strains also resistant to blood plasma (69.2–81.8 %). The present study demonstrated a pronounced bacteriostatic effect of PRP against 88.9 % of multidrug-resistant E. coli isolates and 100 % of K. pneumoniae isolates.

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