Seven-Year Retrospective Analysis of HACEK Bacteria at Istanbul Göztepe Prof. Dr. Süleyman Yalçın City Hospital (2017-2023)

AIM: To retrospectively evaluate the reported cases of HACEK group bacteria at Istanbul Göztepe Prof. Dr. Süleyman Yalçın City Hospital from 2017 to 2023. BACKGROUND: HACEK group bacteria, including Haemophilus parainfluenzae, Aggregatibacter spp., Cardiobacterium hominis, Eikenella corrodens, and Kingella kingae, are recognized endocarditis pathogens that are difficult to culture. These bacteria inhabit the digestive, respiratory, and oropharyngeal microbiota, causing a wide range of opportunistic infections. METHOD: Microbiological samples were inoculated on 5% sheep blood agar, chocolate agar, and chromogenic agar (all from bioMérieux, Marcy-l'Étoile, France) and incubated under appropriate conditions. Species-level identification of cultured bacteria was performed using MALDI-TOF MS (Vitek MS, bioMérieux, France), and antimicrobial susceptibility testing was conducted using E-test strips (bioMérieux, France). RESULTS: Over the 7-year period, HACEK bacteria were reported in 30 patients aged 0-76 years. C. hominis was not detected. The sample diversity ranged widely from sterile body fluids to sputum and abscesses (Table 1). Antimicrobial susceptibility was reported for only 4 samples, and polymicrobial growth was detected in 20 samples. CONCLUSION: The data presented may not fully reflect the true prevalence of HACEK bacteria due to the challenges in culturing these organisms. The current literature is sparse, with most reports from Turkey being limited to individual case presentations. The optimal treatment for HACEK infections remains undetermined due to limited data and the absence of clinical breakpoints. Extensive research is critically needed to enhance our understanding of these pathogens.