Carbapenem-Resistant Klebsiella pneumoniae: Carbapenemase Production, Antibiotic Resistance and Treatment Options, in an Infectious Diseases Hospital from Romania

Background/Objectives: Carbapenem-resistant Klebsiella pneumoniae (CRKP) is of great concern because of the difficulties encountered in the management of infections it may cause. This study aims to identify possible difficulties in the management of K. pneumoniae infections in the current context of antibiotic resistance, particularly regarding carbapenem resistance. Methods: This is a retrospective, cross-sectional study that analyses epidemiological, clinical and bacteriological features identified in all patients with CRKP infections/colonization admitted during 2024 in an infectious diseases hospital. Results: Carbapenemase-producing K. pneumoniae isolates were co-harboring NDM+OXA-48 in 55.2% of cases. NDM+OXA-48-producing K. pneumoniae (116 isolates, 55.2%) was correlated with high resistance to aztreonam (100%, p = 0.01), ceftazidime–avibactam (100%, p < 0.01), trimethoprim–sulfamethoxazole (99.1%, p < 0.01), gentamycin (94.8%, p < 0.01), amikacin (93.8%, p < 0.01), colistin (79.8%, p < 0.01). OXA-48-producing K. pneumoniae (29 isolates, 13.8%) was correlated with lower resistance to ceftazidime–avibactam (11.5%, p < 0.01), amikacin (48.1%, p < 0.01), colistin (51.7%, p = 0.01), and gentamycin (65.5%, p < 0.01). We found in vitro synergistic effects of ceftazidime/avibactam + aztreonam for 32/32 CRKP isolates and of colistin + tigecycline for 12/14 CRKP isolates. Higher recurrence of CRKP infections was recorded in patients with urinary tract conditions (RR = 11.58, 95%CI: 1.58–81.91) and upper urinary tract devices (RR = 3.53, 95% CI: 1.72–7.22). In this study, adequate antibiotic treatment, compared to excessive antibiotic treatment in CRKP infections, was associated with shorter treatment duration (p = 0.02) and shorter length of hospitalization (p = 0.04). Conclusions: In our study, CRKP is frequently coharboring NDM+OXA-48, having limited treatment options. Implementing new treatment strategies, testing antibiotic synergies for older antibiotics in order to identify alternative treatment options and avoiding unnecessary carbapenem consumption are essential for decreasing the burden of CRKP infections.