The Effect of Probiotic Supplement on Urinary D-lactic Acid Level in Newborns
Condition: Antibiotic Side Effect
Study type: Observational

Summary: 
      It is thought that prophylactic enteral probiotics in newborns may play a role in the
      prevention of infection and NEC-related morbidity by preventing bacterial migration in the
      mucosa, reducing their number by competing with pathogenic bacteria, providing microbial
      balance, and increasing intestinal immunity.

      In our study, it was determined to detect normal D-lactic acid levels in urine in late
      premature (babies born after 34 weeks of gestation) and term babies, to show the negative
      effect of antibiotic treatment on the intestinal flora indirectly by measuring urinary
      D-lactic acid, and the probiotic support in babies using antibiotics was disrupted. The
      investigators aim to investigate hypothesis that it will have a corrective effect on the
      intestinal flora by comparing urinary D-lactic acid levels.
    

Detailed description: 
      Lactic acid exists as two optical isomers, L-lactic acid and D-lactic acid. These isomers are
      metabolized to or synthesized from pyruvate by the action of isomer-specific enzymes
      (L-lactate dehydrogenase and D-lactate dehydrogenase). Mammals, including humans, do not
      possess D-lactate dehydrogenase, and therefore D-lactate production in human tissue is very
      limited. The endogenous single D-lactate synthesis known in man is carried out by glyoxalase.
      In this pathway, methylglyoxal is converted into D-lactate by the enzymes glyoxalase-1 and
      glyoxalase-2. Due to this restricted production, the blood D-lactate level in healthy people
      is so low that L-lactate is the major physiological enantiomer of lactate in the human body.

      The bacterial flora in the human gastrointestinal tract has the ability to produce L and / or
      D-lactate depending on the amount of L-LDH and D-LDH present. Some strains of bacteria have
      the enzyme DL-lactate racemase to convert one isomer to another. Therefore, racemization
      reactions can further increase the amount of D-lactate isomers present in the column.
      Although there is no D-lactate dehydrogenase enzyme in humans, D-Lactate is metabolized into
      pyruvate by the enzyme D-2-hydroxy acid dehydrogenase (D-2-HDH), an intramitochondrial
      flavoprotein with high activity in the liver and renal cortex. The kidney's threshold for
      D-lactate is much lower than L-lactate and is efficiently excreted in urine as well as
      metabolic clearance. Thus, under normal conditions, D-lactate produced by tissue metabolism
      or bacterial fermentation in the gut; It does not cause a clinically significant increase in
      lactate in blood, urine or feces.

      D-lactic acidosis is a well-defined complication of short bowel syndrome due to the
      combination of altered gastrointestinal tract anatomy and abnormal bacterial flora. Many case
      reports reported in the literature are associated with short bowel syndrome secondary to
      various causes. There are studies investigating the effects of fermented formulas and
      probiotics on D-lactic acid in healthy babies. In these studies, no increased risk for
      D-lactic acidosis was found in healthy infants fed with probiotic supplemented formulas.

      Considering the studies on newborns; In babies with necrotizing enterocolit, it has been
      shown that urinary D-lactate excretion increased as a result of increased enteric bacterial
      activity. In another study, plasma D-lactic acid level was found to be high in premature
      babies with necrotizing enterocolitis. However, more detailed studies on newborns are needed.
    

Observational model: Cohort
Time perspective: Prospective
Sampling method: Probability Sample
Study population: 
        Healthy newborns who born after 34 weeks of gestation, late preterm and term infants
        receiving antibiotic treatment,
      
Biospecimen description: 
      urine