Acidification of formula reduces bacterial translocation and gut colonization in a neonatal rabbit model.
OBJECTIVE
The authors hypothesized that gastric acidity is protective because it is bactericidal. They tested acidified formula for protection against gut colonization and bacterial translocation.


METHODS
In vitro: Formula was acidified to pH of 2, 3, 4, 5 and innoculated with Enterobacter. Growth over time was quantitatively assessed. In vivo: 442 premature rabbit pups were sorted randomly and fed formula of pH 2, 3, 4, or 7, with ranitidine. Two models were utilized: (1) with bacterial challenge using a known acid sensitive organism, (2) without bacterial challenge to simulate natural gut colonization and to test against organisms of unknown acid sensitivity. Normal acid animals received pH 7 formula, no ranitidine. On day 3, the mesenteric lymph nodes (MLN), spleen, liver, and cecum were harvested and cultured.


RESULTS
Bacterial growth was inhibited at pH 2 and 3, growth was logarithmic above pH 4 (P<.001). Total and organ-specific translocation was reduced at pH 3 and below in both models (P<.05). Translocation with formula pH 3 equaled normal acid animals. Quantitative cecal colonization was reduced in pups receiving pH 3 and below in both models (P<.05).


CONCLUSIONS
Acidification of formula below pH 4 is bactericidal to enteric organisms. Acidified formula decreases bacterial translocation and gut colonization.
Mehall
J R
JR
Department of Pediatric Surgery, Arkansas Children's Hospital, University of Arkansas for Medical Sciences, Little Rock, AK, USA.
Northrop
R
R
Saltzman
D A
DA
Jackson
R J
RJ
Smith
S D
SD
D000818:Animals; D000831:Animals, Newborn; D018988:Bacterial Translocation / Q000502:physiology*; D002432:Cecum / Q000382:microbiology; D016972:Enterobacter cloacae / Q000502:physiology; D005744:Gastric Acid / Q000378:metabolism*; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D006851:Hydrochloric Acid / Q000008:administration & dosage; D006863:Hydrogen-Ion Concentration; D007225:Infant Food; D008099:Liver / Q000382:microbiology; D008198:Lymph Nodes / Q000382:microbiology; D011817:Rabbits; D011899:Ranitidine / Q000494:pharmacology; D013154:Spleen / Q000382:microbiology
D006635:Histamine H2 Antagonists; D011899:Ranitidine; D006851:Hydrochloric Acid