FATAL SEPTIC SHOCK IN HYPERMUCOVISCOUS KLEBSIELLA PNEUMONIAE PNEUMONIA DESPITE IN VITRO ANTIBIOTIC SUSCEPTIBILITY: A CASE REPORT

Background: Klebsiella pneumoniae can cause rapidly progressive severe pneumonia, particularly in older adults with chronic illnesses. A positive string test demonstrates hypermucoviscosity but does not, in isolation, confirm the hypervirulent pathotype.
Case presentation: An 80-year-old woman with type 2 diabetes, hypertension and atrial fibrillation presented after four days of respiratory symptoms and a rapid decline. She had profound hypoxemia (oxygen saturation 80% on room air), persistent hypotension, lactate 5.5 mmol/L and procalcitonin 92 ng/mL. Chest radiography showed bilateral confluent air-space opacities. A tracheal aspirate tested with the BioFire FilmArray Pneumonia Plus panel detected K. pneumoniae group in its highest semiquantitative reporting category (≥10⁷ copies/mL), together with human rhinovirus/enterovirus. Culture yielded K. pneumoniae with markedly mucoid colonies and a positive string test (12 mm). The isolate was reportedly susceptible to cefotaxime and multiple other antibacterial agents. Despite cefotaxime and gentamicin, invasive ventilation and vasopressor support, the patient died 36 hours after admission.
Conclusion: Severe K. pneumoniae pneumonia may have a fatal outcome despite in vitro antimicrobial susceptibility. The positive string test documents hypermucoviscosity; additional specific testing is necessary to establish hypervirulence. Molecular detection categories must be interpreted alongside culture and clinical findings.