Impact of two different colistin dosing strategies on healthy piglet fecal microbiota

Colistin is often used in piglets but underdosing and overdosing are frequent. The impact of such administrations on fecal microbiota was studied. Piglets were given either underdoses of colistin by oral gavage for five days or overdoses by in-feed medication for 14days. The composition of fecal microbiota was studied by quantitative PCR, 16S rRNA sequencing, culture of Enterobacteriaceae, and quantification of short-chain fatty acids (SCFAs). The mean colistin concentrations during the treatment for underdosed and overdosed groups were 14.4μg/g and 64.9μg/g of feces respectively. Whatever the piglet and the sampling day, the two main phyla were Firmicutes and Bacteroidetes, The main families were Lactobacillaceae, Clostridiales, Lachnospiraceae and Ruminococcaceae. The main perturbation was the significant but transitory decrease in the Escherichia coli population during treatment, yet all the E. coli isolates were susceptible to colistin. Moreover, colistin did not affect the production of SCFAs. These results show that under- or overdoses of colistin do not result in any major disturbance of piglet fecal microbiota and rarely select for chromosomal resistance in the dominant E. coli population.

[Severe periventricular leukomalacia: characteristic electroencephalographic features]

Periventricular leukomalacia is an infrequent but severe lesion in the premature neonate. The presence of positive rolandic sharp waves (PRSW) on the electroencephalogram, regardless of their morphology, is a reliable marker of periventricular ischemia, justifying systematic EEG monitoring during the first three weeks of life for infants born at less than 34 weeks of amenorrhea. A retrospective study of 32 premature neonates with extensive cavitary periventricular leukomalacia confirmed the early occurrence of positive rolandic sharp waves in 84% of premature newborns. The mean rate of PRSW was 1.54/min, but showed great variability. In C(Z), these sharp waves which were more frequent or isolated in one case, had the same value as those recorded in C3 or C4. Four neonates had no PRSW, but late periventricular leukomalacia was diagnosed at one month of age. As all these premature infants were born before 29 weeks of amenorrhea, longer EEG monitoring was justified. The prognosis was very poor: 17 newborns died, 11 had motor, sensory and intellectual impairment, and three had motor lesions.

Oxygen cost of breathing in newborn infants with long-term ventilatory support

Oxygen consumption (VO2) was measured during controlled and spontaneous ventilation with continuous positive airway pressure in newborn infants in whom chronic lung disease later developed. The oxygen cost of breathing (the difference in VO2 between spontaneous and controlled ventilation) was significantly higher in infants with chronic lung disease than in control infants (20.1% +/- 7.5% and 4.8% +/- 4.9% of VO2 during spontaneous ventilation (p < 0.05), respectively).