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Updated: May 19, 2026
A Controlled Mouse Model for Neonatal Polymicrobial Sepsis
Published on: January 27, 2019
Appropriate antibiotic therapy improves Ureaplasma sepsis outcome in the neonatal mouse
Leonard E Weisman1, Angela H Leeming, Lingkun Kong
1Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA. lweisman@bcm.edu
Background:
Ureaplasma causes sepsis in human neonates. Although erythromycin has been the standard treatment, it is not always effective. No published reports have evaluated Ureaplasma sepsis in a neonatal model. We hypothesized that appropriate antibiotic treatment improves Ureaplasma sepsis in a neonatal mouse model.
Methods:
Two ATCC strains and two clinical strains of Ureaplasma were evaluated in vitro for antibiotic minimum inhibitory concentration (MIC). In addition, FVB albino mice pups infected with Ureaplasma were randomly assigned to saline, erythromycin, or azithromycin therapy and survival, quantitative blood culture, and growth were evaluated.
Results:
MICs ranged from 0.125 to 62.5 µg/ml and 0.25 to 1.0 µg/ml for erythromycin and azithromycin, respectively. The infecting strain and antibiotic selected for treatment appeared to affect survival and bacteremia, but only the infecting strain affected growth. Azithromycin improved survival and bacteremia against each strain, whereas erythromycin was effective against only one of four strains.
Conclusion:
We have established a neonatal model of Ureaplasma sepsis and observed that treatment outcome is related to infecting strain and antibiotic treatment. We speculate that appropriate antibiotic selection and dosing are required for effective treatment of Ureaplasma sepsis in neonates, and this model could be used to further evaluate these relationships.
Insights
Azithromycin demonstrated improved survival and reduced bacteremia in a neonatal mouse model of Ureaplasma sepsis, unlike erythromycin which was effective against only one strain. This highlights the importance of appropriate antibiotic selection for treating neonatal Ureaplasma infections.
Area of Science:
- Neonatal infections
- Microbiology
- Pharmacology
Background:
- Ureaplasma is a significant cause of sepsis in newborn infants.
- Current treatments like erythromycin are not consistently effective.
- A validated neonatal model for studying Ureaplasma sepsis was lacking.
Purpose of the Study:
- To establish a neonatal mouse model for Ureaplasma sepsis.
- To evaluate the efficacy of azithromycin and erythromycin in treating Ureaplasma sepsis in neonates.
Main Methods:
- In vitro minimum inhibitory concentration (MIC) testing of Ureaplasma strains against antibiotics.
- Infection of neonatal mice with Ureaplasma strains.
- Randomized treatment of infected mice with saline, erythromycin, or azithromycin.
- Evaluation of survival rates, quantitative blood cultures, and bacterial growth.
Main Results:
- Azithromycin showed improved survival and reduced bacteremia across all tested Ureaplasma strains.
- Erythromycin was effective in improving outcomes for only one of the four tested strains.
- Both the infecting Ureaplasma strain and the chosen antibiotic influenced treatment outcomes.
Conclusions:
- A functional neonatal mouse model for Ureaplasma sepsis has been developed.
- Effective treatment of neonatal Ureaplasma sepsis depends on the specific infecting strain and the antibiotic used.
- This model can be utilized to further investigate optimal antibiotic strategies for neonatal Ureaplasma sepsis.
