GASTROENTERITIS AETIOLOGY IN INFANCY: THE ROLE OF KIND OF FEEDING AND AGE

Introduction: Acute diarrhea is still a relevant health problem, particularly in early infancy, not only in developing countries but worldwide. Further, acute gastroenteritis represents an important cause of hospitalisation and morbidity. The knowledge of the major etiologic agents of this disease is important for epidemiological surveillance and more appropriate treatments. The different diarrhoeal syndromes can be caused by bacterial, viral, and parasitic infections, either single, or multiple aetiology. Aim of the study: Our interest was to investigate the prevalence of gastroenteritis in infants and the relationship between gastroenteritis incidence, kind of feeding and age. Moreover we evaluated intestinal microbiota composition using coltural techniques as diagnostic tool in infants affected by gastroenteritis compared with the colonization by these agents in healthy controls. Material and methods: Between December 2009 and May 2010, a total of 164 stool samples were collected from infants aged less than 18 months admitted to the Department of Pediatrics (Regina Margherita Children Hospital, Turin, Italy) and were submitted to the laboratory. All infants were born at term and appropriate for gestational age. Infants were excluded if they suffered from chronic or malformative diseases. We divided the subjects in two groups: in the first one (G1) there were 78 infants affected by acute gastroenteritis, defined by stool volume higher than 10 ml/kg/day or liquid stools, with or without vomiting; in the second group (G2) there were 86 healthy controls. At enrolment, we completed a data record form for each patient, reporting sex, age, breast-feeding or formula feeding; each infant underwent a clinical examination. Informed consent was obtained from each child’s parents. Stool samples were requested from enlisted patients within the first 48 hours of hospitalization. About 5-10 g faeces were collected for each subject directly from the nappy. Each sample was stored at –80°C, immediately after collection, in a numbered screw-capped plastic container, until they were processed, but, not in anaerobic conditions. All samples from hospitalized patients were examined for Escherichia coli, Enterobacter sakazakii, Salmonella spp., Campylobacter spp, Shigella spp., Yersinia spp., Clostridium difficile using standard microbiology procedures. The microbiological analysis was headed using biochemical identification by API 20E system (Biomérieux, France). All fecal samples were examined for Rotavirus and Adenovirus using enzyme immunoassay tests. Statistical analyses were performed using the statistical software SPSS for Windows 17.0 (SPSS, INC. 1989-2003 Chicago, IL). The χ2 test was used for comparisons of proportions. The differences between the groups were considered significant when the P value was < 0.05. Results: During the study period, 164 infants (89 males, 75 females) were recruited. In G1 20 patients were fed with human milk and 58 received formulas, in G2 34 patients were fed with human milk and 52 received formulas. Considering the importance of age in rising of illness, we divided subjects in two groups: from 0 to 6 months (A1) and older than 6 months (A2). We found a significant difference in the occurrence of gastroenteritis according to age (p<0.001), with higher risk in A2 group (RR=3.55). Moreover from the analysis of the single etiologic agents of gastroenteritis we found a more frequent infection by Rotavirus in A2 group (p<0.001; RR=3.45); no significant differences were found in colonization by others pathogens between the two groups of age. In order to detect the possible different risk of developing gastroenteritis depending on kind of feeding, we analysed the occurrence of this disease in breastfed (BF) and formula fed infants (FF). We didn’t found any significant difference in the occurrence of gastroenteritis according to kind of feeding. Moreover we didn’t found any significant difference in the prevalence of intestinal infections by each pathogen studied between the two groups of feeding. Finally, E. coli was isolated in 39% of patients in G1 and in 41% of G2 without a statically significant difference between the two groups. Enterobacter sakazakii was identified in 2 subjects in G1 and in 2 subjects in G2, without significant differences. Discussion and Conclusion: In our study we observed that Rotavirus was the predominant etiologic agent identified (58.9%) in infants with gastroenteritis, according to previous literature data. Frequency of gastroenteritis was higher after the first 6 months of life, particularly for Rotavirus infection. Our data don’t let us to understand the reason of such difference; however we can hypothesize that it could be related to the beginning of attendance of nursery and infant school with the consequence infection risk. The small sample size infected by the other pathogens didn’t let us to remark eventual differences in gastroenteritis aetiology according to the age. It’s well known that human milk protects infants from illness both during breastfeeding and a long time after it. In our study we didn’t found The different diarrhoeal syndromes can be caused by bacterial, viral, and parasitic infections, either single, or multiple aetiology. Aim of the study: Our interest was to investigate the prevalence of gastroenteritis in infants and the relationship between gastroenteritis incidence, kind of feeding and age. Moreover we evaluated intestinal microbiota composition using coltural techniques as diagnostic tool in infants affected by gastroenteritis compared with the colonization by these agents in healthy controls. Material and methods: Between December 2009 and May 2010, a total of 164 stool samples were collected from infants aged less than 18 months admitted to the Department of Pediatrics (Regina Margherita Children Hospital, Turin, Italy) and were submitted to the laboratory. All infants were born at term and appropriate for gestational age. Infants were excluded if they suffered from chronic or malformative diseases. We divided the subjects in two groups: in the first one (G1) there were 78 infants affected by acute gastroenteritis, defined by stool volume higher than 10 ml/kg/day or liquid stools, with or without vomiting; in the second group (G2) there were 86 healthy controls. At enrolment, we completed a data record form for each patient, reporting sex, age, breast-feeding or formula feeding; each infant underwent a clinical examination. Informed consent was obtained from each child’s parents. Stool samples were requested from enlisted patients within the first 48 hours of hospitalization. About 5-10 g faeces were collected for each subject directly from the nappy. Each sample was stored at –80°C, immediately after collection, in a numbered screw-capped plastic container, until they were processed, but, not in anaerobic conditions. All samples from hospitalized patients were examined for Escherichia coli, Enterobacter sakazakii, Salmonella spp., Campylobacter spp, Shigella spp., Yersinia spp., Clostridium difficile using standard microbiology procedures. The microbiological analysis was headed using biochemical identification by API 20E system (Biomérieux, France). All fecal samples were examined for Rotavirus and Adenovirus using enzyme immunoassay tests. Statistical analyses were performed using the statistical software SPSS for Windows 17.0 (SPSS, INC. 1989-2003 Chicago, IL). The χ2 test was used for comparisons of proportions. The differences between the groups were considered significant when the P value was < 0.05. Results: During the study period, 164 infants (89 males, 75 females) were recruited. In G1 20 patients were fed with human milk and 58 received formulas, in G2 34 patients were fed with human milk and 52 received formulas. Considering the importance of age in rising of illness, we divided subjects in two groups: from 0 to 6 months (A1) and older than 6 months (A2). We found a significant difference in the occurrence of gastroenteritis according to age (p<0.001), with higher risk in A2 group (RR=3.55). Moreover from the analysis of the single etiologic agents of gastroenteritis we found a more frequent infection by Rotavirus in A2 group (p<0.001; RR=3.45); no significant differences were found in colonization by others pathogens between the two groups of age. In order to detect the possible different risk of developing gastroenteritis depending on kind of feeding, we analysed the occurrence of this disease in breastfed (BF) and formula fed infants (FF). We didn’t found any significant difference in the occurrence of gastroenteritis according to kind of feeding. Moreover we didn’t found any significant difference in the prevalence of intestinal infections by each pathogen studied between the two groups of feeding. Finally, E. coli was isolated in 39% of patients in G1 and in 41% of G2 without a statically significant difference between the two groups. Enterobacter sakazakii was identified in 2 subjects in G1 and in 2 subjects in G2, without significant differences. Discussion and Conclusion: In our study we observed that Rotavirus was the predominant etiologic agent identified (58.9%) in infants with gastroenteritis, according to previous literature data. Frequency of gastroenteritis was higher after the first 6 months of life, particularly for Rotavirus infection. Our data don’t let us to understand the reason of such difference; however we can hypothesize that it could be related to the beginning of attendance of nursery and infant school with the consequence infection risk. The small sample size infected by the other pathogens didn’t let us to remark eventual differences in gastroenteritis aetiology according to the age. It’s well known that human milk protects infants from illness both during breastfeeding and a long time after it. In our study we didn’t foundThe different diarrhoeal syndromes can be caused by bacterial, viral, and parasitic infections, either single, or multiple aetiology. Aim of the study: Our interest was to investigate the prevalence of gastroenteritis in infants and the relationship between gastroenteritis incidence, kind of feeding and age. Moreover we evaluated intestinal microbiota composition using coltural techniques as diagnostic tool in infants affected by gastroenteritis compared with the colonization by these agents in healthy controls. Material and methods: Between December 2009 and May 2010, a total of 164 stool samples were collected from infants aged less than 18 months admitted to the Department of Pediatrics (Regina Margherita Children Hospital, Turin, Italy) and were submitted to the laboratory. All infants were born at term and appropriate for gestational age. Infants were excluded if they suffered from chronic or malformative diseases. We divided the subjects in two groups: in the first one (G1) there were 78 infants affected by acute gastroenteritis, defined by stool volume higher than 10 ml/kg/day or liquid stools, with or without vomiting; in the second group (G2) there were 86 healthy controls. At enrolment, we completed a data record form for each patient, reporting sex, age, breast-feeding or formula feeding; each infant underwent a clinical examination. Informed consent was obtained from each child’s parents. Stool samples were requested from enlisted patients within the first 48 hours of hospitalization. About 5-10 g faeces were collected for each subject directly from the nappy. Each sample was stored at –80°C, immediately after collection, in a numbered screw-capped plastic container, until they were processed, but, not in anaerobic conditions. All samples from hospitalized patients were examined for Escherichia coli, Enterobacter sakazakii, Salmonella spp., Campylobacter spp, Shigella spp., Yersinia spp., Clostridium difficile using standard microbiology procedures. The microbiological analysis was headed using biochemical identification by API 20E system (Biomérieux, France). All fecal samples were examined for Rotavirus and Adenovirus using enzyme immunoassay tests. Statistical analyses were performed using the statistical software SPSS for Windows 17.0 (SPSS, INC. 1989-2003 Chicago, IL). The χ2 test was used for comparisons of proportions. The differences between the groups were considered significant when the P value was < 0.05. Results: During the study period, 164 infants (89 males, 75 females) were recruited. In G1 20 patients were fed with human milk and 58 received formulas, in G2 34 patients were fed with human milk and 52 received formulas. Considering the importance of age in rising of illness, we divided subjects in two groups: from 0 to 6 months (A1) and older than 6 months (A2). We found a significant difference in the occurrence of gastroenteritis according to age (p<0.001), with higher risk in A2 group (RR=3.55). Moreover from the analysis of the single etiologic agents of gastroenteritis we found a more frequent infection by Rotavirus in A2 group (p<0.001; RR=3.45); no significant differences were found in colonization by others pathogens between the two groups of age. In order to detect the possible different risk of developing gastroenteritis depending on kind of feeding, we analysed the occurrence of this disease in breastfed (BF) and formula fed infants (FF). We didn’t found any significant difference in the occurrence of gastroenteritis according to kind of feeding. Moreover we didn’t found any significant difference in the prevalence of intestinal infections by each pathogen studied between the two groups of feeding. Finally, E. coli was isolated in 39% of patients in G1 and in 41% of G2 without a statically significant difference between the two groups. Enterobacter sakazakii was identified in 2 subjects in G1 and in 2 subjects in G2, without significant differences. Discussion and Conclusion: In our study we observed that Rotavirus was the predominant etiologic agent identified (58.9%) in infants with gastroenteritis, according to previous literature data. Frequency of gastroenteritis was higher after the first 6 months of life, particularly for Rotavirus infection. Our data don’t let us to understand the reason of such difference; however we can hypothesize that it could be related to the beginning of attendance of nursery and infant school with the consequence infection risk. The small sample size infected by the other pathogens didn’t let us to remark eventual differences in gastroenteritis aetiology according to the age. It’s well known that human milk protects infants from illness both during breastfeeding and a long time after it. In our study we didn’t found any significant difference among breast-feeding and formula-feeding infants; this is probably due to the different size between the two groups with different kind of feeding. Molecular analysis of intestinal bacteria are needed to better clarify the possible relationship between kind of feeding and gastroenteritis aetiology and the influence of antibiotic therapy in intestinal colonization by pathogens. Moreover these techniques will help us to better understand the role of each pathogen strains of E. coli in favouring the development acute diarrhoea in hospitalised infants.