medwireNews: Bacterial cultures commonly used to detect infections in low birthweight newborns with early onset neonatal sepsis (EONS) may not be sensitive enough, suggest findings published in PLoS One.
Standard screening methods for EONS include bacterial culture using blood or spinal fluid, but many affected infants often exhibit symptoms of infection that are unconfirmed by culturing.
According to Yiping Han (Case Western Reserve University, Cleveland, Ohio, USA) and co-authors, the study findings support the need for multiple detection methods to identify bacteria that may be uncultivated or difficult to cultivate.
"By using molecular biology identity tools this is the first time we have shown that some microbes could move from the amniotic fluid into the fetal bloodstream," said co-author Catalin Buhimschi (Yale University, New Haven, Connecticut, USA) in an associated press release.
Analysis of paired amniotic fluid and cord blood samples from 36 pregnancies of premature newborns with confirmed intra-amniotic infection and/or EONS revealed a total of 31 bacterial species in amniotic fluid. Of these, 15 unique species were identified as potential etiologic agents of intra-amniotic infection.
Furthermore, DNA genomic analysis of cord blood revealed that only two (Escherichia coli and Streptococcus agalactiae) of the identified 18 bacterial species could be effectively cultivated using current techniques. In total, seven distinct bacterial species were identified as potentially linked to EONS.
Culture detection methods used in routine screening for EONS were unable to identify, for example, oral bacteria Bergeyella, Fusobacterium nucleatum, and Sneathia sanguinegens, thus providing further evidence that oral bacteria can travel into the maternal blood stream and affect the neonate.
The researchers note that the majority (72%) of bacterial species found in the cord blood were also detected in matching amniotic fluid, with E. coli and F. nucleatum the most prevalent. Novel species identified through polymerase chain reaction screening included Peptoniphilus harei and Lachnospiraceae sp.
Given that standard management is administration of antibiotics for 3 days, possibly leading to an increase in antibiotic-resistant bacteria, co-author Vineet Bhandari (Yale University, New Haven, Connecticut) commented in a press release: "This research is important in finding the right bug to target for antibiotics." The researchers caution that culture-dependent and independent methods complement, but cannot entirely replace, each other. "We anticipate that many more species will be discovered to be involved in pregnancy complications using the culture-independent technologies," they conclude.
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