Appropriate antibiotic therapy improves Ureaplasma sepsis outcome in the neonatal mouse.
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.


CONCLUSIONS
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.
Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA. lweisman@bcm.edu
Leonard E
LE
Weisman
Angela H
AH
Leeming
Lingkun
L
Kong
D000818:Animals; D000831:Animals, Newborn; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D017963:Azithromycin / Q000494:pharmacology*; D016470:Bacteremia / Q000188:drug therapy / Q000382:microbiology; D004195:Disease Models, Animal; D004917:Erythromycin / Q000494:pharmacology*; D005260:Female; D006801:Humans; D051379:Mice; D008826:Microbial Sensitivity Tests; D011247:Pregnancy; D018805:Sepsis / Q000175:diagnosis / Q000188:drug therapy* / Q000382:microbiology; D014509:Ureaplasma / Q000145:classification / Q000187:drug effects* / Q000254:growth & development; D016869:Ureaplasma Infections / Q000175:diagnosis / Q000188:drug therapy* / Q000382:microbiology; D016990:Ureaplasma urealyticum / Q000187:drug effects
D000900:Anti-Bacterial Agents; D004917:Erythromycin; D017963:Azithromycin