The Effect of Postnatal Development on the Adherence of Nonfimbriated and Fimbriated Salmonella typhimurium to Isolated Small Intestinal Enterocytes

Abstract

The adherence of radiolabeled fimbriated (S 7471 OF) and nonfimbriated (S 7471 N) Salmonella typhimurium to small intestinal rat enterocytes was examined during postnatal development. The fimbriated strain invariably adhered in higher numbers than the nonfimbriated strain during all periods of development. The capability of enterocytes to bind Salmonella increased significantly during postnatal development and reached adult levels at weaning time (21 days of age). Bacterial adherence to enterocytes was similar if the cells were isolated from the proximal or the distal small intestine. Early weaning of pups did not affect the capability of enterocytes to bind Salmonella. Pretreatment of isolated enterocytes from adult animals with rat's milk before exposure to Salmonella had no effect on the level of bacteria that adhered per enterocyte. Conversely, pretreatment of Salmonella with rats' milk before binding to enterocytes from adult animals also did not alter the level of bacteria adhered per enterocyte. These results suggest an age-dependent, postnatal development of available receptors for S. typhimurium on rat enterocytes. The acquisition of these receptors is not affected by mother's milk and is unaltered by early weaning.

The ability of probiotic bacteria to bind to human intestinal mucus

“…It has been shown previously that the composition and degradation of intestinal mucin is altered during postnatal development and in response to changes in diet [6, 7]. In many animal studies, the number of receptors available for some pathogens, in intestinal mucus and enterocytes, have been shown to increase postnatally [8–11]. In addition, the intestinal Lactobacillus population has been shown to change during infancy [5, 12].…”

Transient, asymptomatic colonisation of newborn, ethiopian infants by salmonella

“…Breast milk apparently protects colonised infants from developing clinical salmonella as well as shigella enteritis [8,9]. The lack of symptoms may also be correlated to an absence of receptors on enterocyte surfaces, as demonstrated in suckling rats [10]. The transient nature of such colonisation may reflect a general instability of the intestinal bacterial microflora in the neonatal period, and similar patterns have been reported for other species [11].…”

The Effect of Postnatal Age on the Adherence of Enterohemorrhagic Escherichia coli to Rabbit Intestinal Cells

“…Considerable differences were found in the protein subunits of mannose-sensitive adhesins of various bacteria, which may occur on the surface of the bacteria as pili or as part of the outer membranes (28). This proposed diversity of the mannose-binding mechanisms may explain why postnatal age increased the adherence of S. typhimurium (19) but not that of E. coli 0128:H4 (17), although both bacterial strains attached by a mannose-sensitive mechanism. Also, the different growth conditions and experimental systems that have been used may be of importance.…”

“…Developmental changes in surface carbohydrate residues may obviously affect bacterial adherence. Animals studied with a few other bacteria have shown age-related differences in bacterial attachment to isolated intestinal cells or brush border membranes (16)(17)(18)(19). In particular, the adherence of E. coli strain RDEC-1, a rabbit pathogen, to rabbit brush border membranes increases with age (18), as does the attachment of Salmonella typhimurium to rat intestinal cells ( I 9).…”

“…Postnatal age has a significant influence on the development of the intestinal tract, appearance of surface proteins and carbohydrates, and binding of various bacteria (1 6- 19). As yet, there are no ontogenic studies on the intestinal adherence of EHEC.…”