Delay in antibiotic therapy results in fatal disease outcome in murine pneumococcal pneumonia

Crit Care. 2018 Nov 1;22(1):287. doi: 10.1186/s13054-018-2224-5.


Background: Community-acquired pneumonia (CAP) remains a major cause of death worldwide. Mechanisms underlying the detrimental outcome despite adequate antibiotic therapy and comorbidity management are still not fully understood.

Methods: To model timely versus delayed antibiotic therapy in patients, mice with pneumococcal pneumonia received ampicillin twice a day starting early (24 h) or late (48 h) after infection. Clinical readouts and local and systemic inflammatory mediators after early and late antibiotic intervention were examined.

Results: Early antibiotic intervention rescued mice, limited clinical symptoms and restored fitness, whereas delayed therapy resulted in high mortality rates. Recruitment of innate immune cells remained unaffected by antibiotic therapy. However, both early and late antibiotic intervention dampened local levels of inflammatory mediators in the alveolar spaces. Early treatment protected from barrier breakdown, and reduced levels of vascular endothelial growth factor (VEGF) and perivascular and alveolar edema formation. In contrast, at 48 h post infection, increased pulmonary leakage was apparent and not reversed by late antibiotic treatment. Concurrently, levels of VEGF remained high and no beneficial effect on edema formation was evident despite therapy. Moreover, early but not late treatment protected mice from a vast systemic inflammatory response.

Conclusions: Our data show that only early antibiotic therapy, administered prior to breakdown of the alveolar-capillary barrier and systemic inflammation, led to restored fitness and rescued mice from fatal streptococcal pneumonia. The findings highlight the importance of identifying CAP patients prior to lung barrier failure and systemic inflammation and of handling CAP as a medical emergency.

Keywords: Acute lung injury; Ampicillin; Bacterial pneumonia; Blood–air barrier; Innate immunity; Streptococcus pneumoniae.

MeSH terms

  • Ampicillin / administration & dosage
  • Ampicillin / therapeutic use
  • Analysis of Variance
  • Animals
  • Anti-Bacterial Agents / administration & dosage*
  • Anti-Bacterial Agents / therapeutic use
  • Bronchoalveolar Lavage Fluid / cytology
  • Chemokine CCL2 / analysis
  • Chemokine CCL2 / blood
  • Chemokine CCL3 / analysis
  • Chemokine CCL3 / blood
  • Disease Models, Animal
  • Enzyme-Linked Immunosorbent Assay / methods
  • Female
  • Mice
  • Mice, Inbred C57BL
  • Pneumonia, Pneumococcal / drug therapy*
  • Pneumonia, Pneumococcal / mortality*
  • Statistics, Nonparametric
  • Streptococcus pneumoniae / drug effects
  • Streptococcus pneumoniae / pathogenicity
  • Survival Analysis
  • Time Factors*


  • Anti-Bacterial Agents
  • Ccl2 protein, mouse
  • Ccl3 protein, mouse
  • Chemokine CCL2
  • Chemokine CCL3
  • Ampicillin