Bloodstream Infections Caused by Klebsiella-Enterobacter-Serratia Group Enterobacterales at Dalal Jamm National Teaching Hospital (Dakar, Senegal) in 2024: Resistance Profiles and β-Lactam Resistance Phenotypes
Background: Enterobacterales of the Klebsiella-Enterobacter-Serratia (KES) group are among the leading causes of healthcare-associated bloodstream infections and concentrate resistance mechanisms that compromise empirical therapy. Blood culture-based data from Senegal remain scarce. We aimed to describe the frequency, susceptibility profiles and β-lactam resistance phenotypes of KES-group bloodstream infections at Dalal Jamm National Teaching Hospital. Methods: We conducted a retrospective descriptive study of all blood cultures processed in the Bacteriology-Virology laboratory of Dalal Jamm National Teaching Hospital between January and December 2024. The unit of microbiological analysis was the isolate; the unit of clinical description was the blood culture episode, defined as all bottles drawn from one patient within a 14-day window. Isolates were identified using API 20E strips and the Vitek 2 system; antimicrobial susceptibility testing was performed on Vitek 2 and interpreted according to CA-SFM/EUCAST breakpoints. Non-susceptibility combined the intermediate and resistant categories and is reported both by individual agent and by class. β-lactam resistance phenotypes were inferred from antibiogram profiles using a pre-specified algorithm that required a cefoxitin result; isolates without one were reported as not classifiable. Multidrug resistance was defined according to Magiorakos et al., after exclusion of species-specific intrinsic resistance. Results: Of 1844 blood cultures processed, 694 (37.6%) were positive and 589 isolates were considered significant after exclusion of 105 contaminants. Gram-negative bacilli accounted for 386 isolates (65.5%), of which 117 belonged to the KES group, representing 30.3% of Gram-negative bacilli and 19.9% of all significant isolates. Four isolates had no analysable antibiogram, leaving 113 isolates recovered from 110 blood culture episodes in at least 103 patients. Enterobacter spp. predominated (n = 53; 46.9%), closely followed by Klebsiella pneumoniae (n = 51; 45.1%) and then Serratia spp. (n = 9; 8.0%); only 10 of the 53 Enterobacter isolates (18.9%) carried a species-level identification. Paediatric units (neonatology, general paediatrics and paediatric oncology) accounted for 39.1% of episodes, ahead of the intensive care unit (14.5%) and clinical haematology (12.7%); 40.9% of episodes concerned children aged 10 years or younger. Median time to positivity was 1 day (IQR 1 - 2). Non-susceptibility
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