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Effects of oral antibiotics on stool flora and overall sensitivity patterns in an intensive care nursery
Insights
Oral gentamicin and colistin altered newborn gut bacteria, increasing resistance. Colistin showed a trend towards lower necrotizing enterocolitis rates in at-risk infants.
Area of Science:
- Neonatal medicine
- Microbiology
- Pharmacology
Background:
- Neonatal necrotizing enterocolitis (NEC) is a serious condition in premature infants.
- Antibiotic use in newborns can impact gut microbiota and antibiotic resistance.
- Gentamicin and colistin are commonly used antibiotics in neonatal care.
Purpose of the Study:
- To evaluate the effects of oral gentamicin and colistin on neonatal stool bacterial flora.
- To assess changes in antibiotic sensitivity patterns in at-risk newborns.
- To compare the incidence of NEC in infants receiving gentamicin versus colistin.
Main Methods:
- 100 newborns at risk for NEC were randomly assigned to receive oral gentamicin or colistin for 3 weeks.
- Stool cultures were collected on days 1, 11, and 21 for bacterial analysis.
- Antibiotic sensitivity testing was performed on isolated Gram-negative bacteria.
Main Results:
- Staphylococcus epidermidis was the most common organism; E. coli and Klebsiella were the most frequent Gram-negative bacteria.
- Gram-negative bacteria showed increasing resistance to colistin (17%) and gentamicin (9%) over the 3-week period.
- E. coli and Klebsiella maintained high sensitivity (>95%) to aminoglycosides like kanamycin and gentamicin, with a minor dip.
- The incidence of NEC was low (1/50 in gentamicin group, 0/50 in colistin group), with no statistically significant difference.
Conclusions:
- Oral gentamicin and colistin significantly alter neonatal gut flora and increase antibiotic resistance.
- Colistin may be associated with a lower incidence of NEC compared to gentamicin, though not statistically significant.
- Continued monitoring of antibiotic resistance patterns in neonatal intensive care units is crucial.
Abstract:
The effects of orally administered gentamicin and colistin on stool bacterial flora and overall antibiotic sensitivity patterns were evaluated in 100 newborns at risk for neonatal necrotizing enterocolitis. Gentamicin (2.5 mg/kg q6h) and colistin (1 mg/kg q6h) were administered to randomly selected groups of 50 newborns for 3 wk after birth during an 11-month study period. Stools were collected on days 1, 11, and 21 and cultures were grown under aerobic conditions on three different media. Staph. epidermidis was the most common predominant organism in both antibiotic groups, whereas E. coli and Klebsiella were the most common Gram-negative bacteria isolated. Seventeen % of these Gram-negative species were resistant to colistin and 9% to gentamicin, with a gradual increase occurring during the 3-wk period. On the basis of 980 positive cultures from all sites in babies in the nursery during the 11-month study, E. coli sensitivity to kanamycin and gentamicin ranged between 92% and 100% except for one month midway through the study when sensitivity to kanamycin was at 80% and then returned to the 92-100% range. Klebsiella sensitivity to both aminoglycosides remained greater than 95% throughout. The incidence of neonatal sepsis remained consistent at seven to nine per 1000 live births during the study. One baby of 50 in the gentamicin group developed necrotizing enterocolitis at 5 wk of age; 0/50 in the colistin group had necrotizing enterocolitis (not significant).