From the Research
Klebsiella pneumoniae exhibits a bulging sign due to the rapid accumulation of inflammatory exudate in the lungs, which is a result of the bacteria's ability to resist phagocytosis and induce a robust inflammatory response. The mechanism behind this sign can be explained by the following points:
- Klebsiella bacteria produce a thick, sticky capsule that resists phagocytosis, as noted in various studies 1, 2.
- This leads to a robust inflammatory response with copious exudate production, which is characterized by the activation of various signaling pathways, including the MAPK and NF-κB pathways 1.
- The exudate fills the alveoli and spreads along the path of least resistance, which is often the lung fissures.
- As the fissure fills with fluid, it appears to bulge outward on X-ray imaging, resulting in the characteristic bulging sign. It's worth noting that the epidemiology of Klebsiella pneumoniae infections is changing, with a rising burden of both Kp-BSI and 3GC-R blood isolates in previous low-prevalence settings 3. Additionally, the emergence of hypervirulent K. pneumoniae poses a serious clinical therapeutic challenge and is associated with a high mortality 4. Recognizing the bulging sign can help clinicians suspect Klebsiella as the causative organism and guide initial antibiotic therapy, typically with a third-generation cephalosporin or carbapenem, depending on local resistance patterns.