J Korean Med Sci. 2004 Jun;19(3):333-40. Related Articles, Links

Bacterial growth in amniotic fluid is dependent on the iron-availability and
the activity of bacterial iron-uptake system.

Ahn YJ, Park SK, Oh JW, Sun HY, Shin SH.

Department of Pediatrics, Seonam University Medical School, Namwon, Korea.
shsin@chosun.ac.kr

In the present study, the relationship among iron-availability, antibacterial
activity, role of meconium as an iron source and the activity of bacterial
iron-uptake system (IUS) for bacterial growth in amniotic fluid (AF) were
investigated. Staphylococcus aureus ATCC 6538 and its streptonigrin-resistant
(SR) mutant with defective IUS were used as the test strains. The growth of S.
aureus in AF was stimulated dosedependently by addition of meconium. Bacterial
growth stimulated by meconium was re-inhibited dose-dependently by addition of
iron-chelator, dipyridyl and apotransferrin. Iron concentration was correlated
with the meconium content in AF (r(2)= 0.989, p=0.001). High-affinity IUS of S.
aureus was expressed only in AF but not in AF with meconium. The growth of SR
strain was more retarded than that of the parental strain in the iron-deficient
brain heart infusion (ID-BHI), clear AF and AF containing apotransferrin. The
retarded growth of both strains in the ID-BHI and AF was recovered by addition
of holotransferrin, hemoglobin and FeCl3. Taken together, the antibacterial
activity of AF is closely related with low iron-availability. Bacterial growth
in AF considerably depends on the activity of bacterial IUS. Meconium acts as
one of the exogenous iron-sources and thus can stimulate bacterial growth in
AF.

PMID: 15201496 [PubMed - in process]

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