Severe Klebsiella pneumoniae Pneumonia Complicated by Secondary Coagulation Disorders in a Premature Infant : A case report

Technical Summary: Severe Klebsiella pneumoniae Pneumonia Complicated by Secondary Coagulation Disorders in a Premature Infant

Problem Statement
Premature neonates possess a physiologically immature hemostatic system, characterized by developmental differences in coagulation factors, natural anticoagulants, and hepatic synthetic capacity. This "developmental hemostasis" renders them uniquely vulnerable to acquired coagulation abnormalities during acute illnesses such as sepsis and severe pneumonia. While severe infections like those caused by Klebsiella pneumoniae can trigger systemic inflammation, endothelial activation, and cytokine release, the specific presentation of secondary coagulation disorders in preterm infants can mimic congenital bleeding disorders (e.g., hemophilia) or Disseminated Intravascular Coagulation (DIC). The clinical challenge lies in differentiating these acquired, reversible conditions from congenital pathologies or severe consumptive coagulopathies to avoid unnecessary interventions while preventing silent hemorrhagic emergencies.

Methodology and Case Presentation
This report details the clinical course of a 21-day-old male infant born at 34 weeks' gestation following maternal preeclampsia. The infant was admitted with signs of severe respiratory distress (tachypnea, wheezing, chest retractions) and diagnosed with severe pneumonia and acute laryngitis.

• Diagnostic Approach: The team utilized a comprehensive diagnostic protocol including nasopharyngeal cultures, chest radiography, cranial ultrasound, and serial coagulation profiles.
• Initial Findings: The nasopharyngeal culture was positive for Klebsiella pneumoniae. Initial coagulation testing revealed a combined prolongation of Activated Partial Thromboplastin Time (APTT) and Prothrombin Time (PT)/International Normalized Ratio (INR), with a low-normal fibrinogen level and elevated platelet count (500 G/L). Notably, the infant presented with no overt clinical bleeding (no petechiae or mucosal bleeding).
• Clinical Course: The infant was treated with intravenous cefazolin. While respiratory symptoms improved over seven days, a repeat coagulation profile on Day 7 showed a paradoxical and marked worsening of coagulation parameters: APTT increased to 137 seconds (ratio 4.35), and prothrombin activity dropped to 5%.
• Intervention: Suspecting an acquired secondary coagulopathy, the team administered intravenous Vitamin K1 (1 mg) and Fresh Frozen Plasma (FFP, 55 mL). Specialized testing for endogenous coagulation inhibitors was performed to rule out acquired antibodies.

Key Results

• Response to Treatment: Following the administration of Vitamin K1 and FFP, coagulation parameters improved rapidly. The APTT decreased from 137 seconds to 54.6 seconds, and prothrombin parameters normalized.
• Factor Analysis: Subsequent testing revealed mildly decreased Factor VIII activity (33%) and Factor IX activity (25%). These levels were insufficient to diagnose severe congenital hemophilia (typically defined by activity <1%) and were inconsistent with the isolated APTT prolongation seen in classic hemophilia.
• Exclusion of Other Causes:
  • DIC: Ruled out by the elevated platelet count and low-normal fibrinogen, which argued against severe consumptive coagulopathy.
  • Inhibitors: Testing for acquired inhibitors of the intrinsic pathway was negative.
  • Intracranial Hemorrhage: Serial cranial ultrasounds remained normal, confirming no intracerebral bleeding despite the severe coagulopathy.
• Outcome: The infant was discharged on Day 14 with normalized coagulation tests, resolved respiratory symptoms, and a weight gain from 2.5 kg to 3.0 kg.

Key Contributions and Claims
The paper contributes a specific case study illustrating the complex interplay between severe Gram-negative infection, prematurity, and acquired coagulopathy. The authors claim that:

1. Multifactorial Etiology: The coagulation disorder was likely multifactorial, resulting from the convergence of prematurity (baseline vulnerability), acute Klebsiella infection (systemic inflammation and endothelial effects), and potential Vitamin K deficiency exacerbated by antibiotic therapy and limited hepatic reserves.
2. Diagnostic Differentiation: The case highlights the necessity of distinguishing secondary coagulation disorders from congenital hemophilia and DIC. The simultaneous prolongation of both PT and APTT, combined with the rapid response to Vitamin K and FFP, supports an acquired, reversible mechanism rather than a congenital defect.
3. Clinical Management: The authors advocate for proactive coagulation screening in premature neonates with severe infections, even in the absence of overt bleeding. They emphasize that timely combined therapy with Vitamin K1 and FFP is an optimal, safe approach to stabilize hematologic function in high-risk neonates.
4. Antibiotic Considerations: While noting that evidence linking first-generation cephalosporins to coagulopathy is inconsistent, the authors suggest that antibiotic therapy may reduce intestinal flora involved in Vitamin K production, contributing to the hypoprothrombinemia observed.

Significance
The paper underscores that severe respiratory infections in premature infants can precipitate "silent" hematologic emergencies with a high risk of bleeding. It argues that interpreting abnormal coagulation tests in neonates requires an understanding of developmental hemostasis and should not rely on adult reference ranges. The authors conclude that in-depth clinical experience and targeted screening are essential to rule out congenital pathologies and guide treatment toward the infectious agent and supportive hemostatic therapy, thereby avoiding unnecessary blood product interventions while ensuring patient safety.