What is Klebsiella pneumoniae pneumonia?

Klebsiella pneumoniae pneumonia is a serious bacterial infection of the lungs caused by the Gram-negative bacillus Klebsiella pneumoniae. It is most commonly seen in individuals with significant underlying comorbidities—particularly chronic alcohol use disorder, diabetes mellitus, chronic obstructive pulmonary disease (COPD), immunosuppression, or recent hospitalization or residence in long-term care facilities. Unlike community-acquired pneumonia caused by Streptococcus pneumoniae, K. pneumoniae pneumonia often presents with abrupt onset of high fever, chills, productive cough with thick, viscous, blood-tinged or “currant jelly”–appearing sputum, and pleuritic chest pain. Radiographically, it frequently manifests as lobar consolidation—often involving the upper lobes—with a tendency toward rapid progression, cavitation, abscess formation, and pleural effusion.

This pathogen is notable for its prominent polysaccharide capsule, which confers resistance to phagocytosis and contributes to its virulence. Many clinical isolates are multidrug-resistant (MDR), including extended-spectrum beta-lactamase (ESBL)-producing and carbapenem-resistant strains, posing substantial therapeutic challenges. Empiric antibiotic therapy must be guided by local resistance patterns and severity of illness; options may include broad-spectrum beta-lactam/beta-lactamase inhibitor combinations, carbapenems (in non-carbapenem-resistant cases), or newer agents such as ceftazidime-avibactam or meropenem-vaborbactam for resistant isolates. Definitive treatment requires culture and susceptibility testing of respiratory specimens (e.g., sputum, blood, or bronchoalveolar lavage fluid). Prompt recognition, appropriate antimicrobial selection, and supportive care—including oxygenation, hydration, and management of sepsis—are critical to improving outcomes, as mortality remains elevated—especially among critically ill or immunocompromised patients.