Antibiotic resistance and occurrence of extended-spectrum beta-lactamases, AmpC and carbapenemases in Klebsiella pneumoniae from blood cultures in Southern Ghana

Antibiotic-resistant Klebsiella pneumoniae presents a significant global health threat, prompting urgent calls for new treatment options. This study determined antibiotic resistance profiles of K. pneumoniae isolates from blood cultures in Southern Ghana and characterized the β-lactamase enzymes mediating β-lactam resistance. Archived K. pneumoniae isolates stored at -80°C at the Department of Medical Microbiology, University of Ghana Medical School were retrieved and revived for the study. Isolate identities were confirmed using the BD Bruker MALDI-TOF. Antimicrobial susceptibility testing was performed using both the MicroScan AutoSCAN system and Kirby-Bauer disc diffusion method. Of the 109 non-duplicate archived isolates, 95 (87.2%) were confirmed as K. pneumoniae . All confirmed isolates exhibited resistance to at least one antibiotic class, with two isolates (2.1%) resistant to all tested antibiotics. High resistance rates were observed for trimethoprim-sulfamethoxazole (85.3%), gentamicin (83.2%), ceftriaxone (80.0%), cefotaxime (78.9%), and ceftazidime (77.9%). Resistance to ertapenem (18.9%), and meropenem (8.4%) was comparatively lower. β-Lactamase enzyme profiles revealed that 77.9% (n = 74/95) of screened isolates were extended-spectrum beta-lactamase (ESBL) producers, 51.6% (n = 47/91) were AmpC producers, 26.6% (n = 17/64) were carbapenemase-producers, and 12.5% (n = 6/48) exhibited resistance to colistin. Notably, 12.5% of isolates concurrently produced ESBL, AmpC, and carbapenemase enzymes and were resistant to colistin. The prevalence of ESBL-producing K. pneumoniae was higher among children under five years of age compared to adults over sixty, though the difference was not statistically significant ( p =  0.933). All ESBL-producing isolates were multidrug-resistant (MDR), and 76.2% (n = 21) of non-ESBL producers were also MDR. AmpC-producing isolates were significantly more prevalent among children under five than among those aged 5–19 and adults over sixty ( p  = 0.023). The high prevalence of MDR K. pneumoniae strains producing ESBLs, AmpCs, carbapenemases, and exhibiting colistin resistance is alarming and significantly narrows treatment options for bloodstream infections. These findings highlight the urgent need for alternative therapeutic strategies and routine surveillance to guide effective clinical management and antimicrobial stewardship.