Lactobacilli and bifidobacteria in the feces of schoolchildren of two different socioeconomic groups: children from a favela and children from a private school.

Objective: To determine the number of lactobacillus and bifidobacterium colonies in the feces of schoolchildren from two different socioeconomic levels.

Methods: We analyzed fecal samples of children aged 6 to 10 years without gastrointestinal symptoms or recent use of antimicrobials. The first group included 86 children living in a favela in the city of Osasco, state of São Paulo, southeastern Brazil. The second group included 36 children attending a private school in the same city. Body mass index (BMI) was used to assess nutritional status according to the reference values of the National Center for Health Statistics (NCHS). Specific anaerobic culture media were used for isolation of colonies for 48 and 72 hours at 37 degrees C. The number of colonies was determined using the plate-counting method.

Results: The mean lactobacillus (1.125 x 10(9) colony-forming units, CFU/g) and bifidobacterium (1.675 x 10(9) CFU/g) counts in the private school group were higher (p < 0.001) than those in the favela group: 0.250 x 10(9) and 0.350 x 10(9) CFU/g, respectively. In the favela group, children with BMI z score < -1.0 standard deviation (SD) (n = 28) showed lower mean (p < 0.05) lactobacillus (0.100 x 10(9) CFU/g) and bifidobacterium (0.095 x 10(9) CFU/g) counts than the children with BMI >or= -1.0 SD (n = 57): 0.350 x 10(9) and 0.420 x 10(9) CFU/g, respectively.

Conclusion: The microbiota of schoolchildren living in unfavorable environmental conditions shows lower numbers of fecal lactobacillus and bifidobacterium colonies, especially in children with lower BMI values.