Impact of medium-chain monoglycerides on intestinal colonisation by Vibrio cholerae or enterotoxigenic Escherichia coli.

Although a number of studies have shown that various free fatty acids (FFAs) and monoacylglycerides (MGs) have bactericidal properties in vitro, the role of these compounds in vivo has not been determined. This study evaluated the antibacterial properties of medium-chain MGs and FFAs for different bacterial enteropathogens with an in-vitro bacterial killing assay and an in-vivo model of intestinal colonisation. Incubation of test bacteria with medium-chain MGs for 4 h led to 100-10,000-fold reductions in numbers of viable cells of Vibrio cholerae, Salmonella typhi, Shigella sonnei and enterotoxigenic Escherichia coli (ETEC). Lauric acid was the only medium-chain FFA to show comparable in-vitro bactericidal activity. The ability of dietary MGs to reduce or eliminate bacterial colonisation of the intestinal tract was evaluated in mice that were predisposed to bacterial colonisation by treatment with streptomycin (STR+). Mice were treated with streptomycin, challenged intragastrically with V. cholerae or ETEC, and given monocaprin (C10:0 MG) either concurrently or as part of the daily diet. Control mice given STR+ without MGs and challenged with V. cholerae or ETEC showed high numbers of challenged bacteria in gastrointestinal contents by 1 h after administration. Concurrent administration of V. cholerae and C10:0 MG (2.5 mg/ml) caused > 1000-fold reduction in numbers of V. cholerae recovered from the gastrointestinal tracts of STR+ mice. Concurrent administration of C10:0 MG with ETEC did not cause a reduction in the number of viable ETEC present in the intestinal tract of STR+ mice. Administration of C10:0 MG in the diet had no effect on the number of viable V. cholerae or ETEC associated with caecal or ileal tissue of STR+ mice when C10:0 MG in the diet was started 1 day before, the same day, or 2 days after bacterial challenge. Collectively, these results suggested that dietary MGs may prevent intestinal colonisation by bacterial enteropathogens if administered at the time of exposure, but have little effect on established intestinal infections.

Reduction in virus-neutralizing activity of a bovine colostrum immunoglobulin concentrate by gastric acid and digestive enzymes.

Bovine milk immunoglobulin concentrates have been proposed for inducing passive immunity against various enteric pathogens. In vitro digestion studies were conducted to evaluate the effect of gastrointestinal secretions on the virus-neutralizing activity of a concentrate prepared from the colostrum of cows that were immunized with rotavirus. The proteolytic activity of human gastric and duodenal fluid specimens was used to design a two-stage in vitro digestion model with commercial enzymes for estimating the individual impact of pepsin, gastric acid, and select pancreatic enzymes on antirotavirus activity in bovine milk immunoglobulin concentrates. The rotavirus-neutralizing titer of concentrate was decreased by incubation with pepsin at pH 2, a pool of pancreatic enzymes at pH 7.5, or sequential digestion with pepsin (pH 2) and pancreatic enzymes (from initial titer of 55,210 to 2,030, 19,500, and 320, respectively). Reduction in rotavirus-neutralizing titer after gastric-phase digestion was primarily due to acidic conditions and not to proteolytic cleavage by pepsin. Although both trypsin and carboxypeptidase caused significant proteolysis of concentrate during duodenal-phase digestion, only trypsin caused a significant reduction in rotavirus-neutralizing titer. The extent of digestion was the same for concentrate suspended in water or skim milk. The results demonstrate that the biological activity of bovine milk antibodies is reduced by exposure to acid and trypsin in vitro and suggest that neutralization of both gastric acid and pancreatic trypsin may enhance the effectiveness and economic feasibility of passive oral immunoprophylaxis with bovine milk immunoglobulins.

Response of bifidobacterium species to growth promoters in human and cow milk.

We used an in vitro assay to study and compare the growth-promotional activity of protein and nonprotein components in human milk (HM) and cow milk (CM) samples for infant strains of Bifidobacterium species. HM samples varied considerably in growth-promotion activity for Bifidobacterium bifidum var pennsylvanicus, Bifidobacterium infantis, and Bifidobacterium breve. Pooled CM samples showed similar but less variable levels of activity when compared with HM samples. Separation of milk samples by ultrafiltration into protein nitrogen and nonprotein nitrogen (NPN) fractions revealed that the bifidobacteria growth-promotion activity of HM was associated primarily with the NPN fraction, whereas activity in CM whey was found in both protein nitrogen and NPN fractions. Testing of purified CM whey proteins showed that alpha-lactalbumin and lactoferrin were potent growth promoters, showing greater activity for B. infantis and B. breve than for two strains of B. bifidum. Conversely, N-acetylglucosamine and purified gastric mucin were highly active for B. bifidum strains but inactive for other Bifidobacterium species. Collectively, the data indicate that both protein nitrogen and NPN factors in HM and CM promote the growth of bifidobacteria and suggest that Bifidobacterium species differ in responsiveness to protein and oligosaccharide growth promoters.

Luxatio erecta humeri. A case report.

Luxatio erecta humeri is a rare type of glenohumeral dislocation. The pathomechanics of this injury involve either direct axial loading on a fully abducted extremity or leverage of the humeral head across the acromion by a hyperabduction force. The clinical presentation of this type of shoulder dislocation is unique, with the affected extremity held rigidly above the head in abduction. Reduction is accomplished by a form of traction-countertraction under intravenous sedation and analgesia. A variety of neurologic and vascular injuries may be associated with luxatio erecta humeri, involving the brachial plexus and axillary artery, respectively. Concomitant fracture of the acromion, clavicle, coracoid, greater tuberosity, and humeral head may also be seen. A computed tomography scan of the case reviewed here revealed a large humeral head defect oriented perpendicular to the classic Hill-Sachs lesion. Luxatio erecta humeri is associated with significant late morbidity, including recurrent dislocation, instability, and adhesive capsulitis.

Growth promotion of Bifidobacterium species by whey and casein fractions from human and bovine milk.

An in vitro assay was used to study the growth-promotional activity of human milk (HM), cow's milk (CM), and whey and casein fractions of HM and CM for five strains of Bifidobacterium species isolated originally from stools of human infants. Whey- and casein-predominant CM-based infant formulas were studied as well. When compared on an equivalent protein basis, the growth promotion activity of HM was greater than that of CM for Bifidobacterium bifidum serovar pennsylvanicus and Bifidobacterium longum but comparable for B. bifidum, Bifidobacterium infantis, and Bifidobacterium breve. Pasteurization of HM and CM resulted in an increase of growth promotion activity for B. bifidum serovar pennsylvanicus and B. bifidum, a decrease for B. infantis, and no change for B. longum and B. breve. The growth promotion activity of HM whey was slightly higher than that of HM casein for four strains of bifidobacteria. When CM casein was a substrate, virtually no growth occurred for B. bifidum serovar pennsylvanicus, B. bifidum, B. infantis, and B. longum. The growth promotion activity of CM whey, however, was similar to that of HM whey. A similar trend was observed for CM-based infant formula. Whey-dominant formulas promoted better growth of B. bifidum serovar pennsylvanicus, B. bifidum, and B. infantis than casein-dominant formulas. The data suggest a direct relationship between amount of whey-specific factors and the ability to promote growth of clinically relevant strains of Bifidobacterium species by HM, CM, and CM-based infant formulas.

The effect of previous surgery, operating room environment, and preventive antibiotics on postoperative infection following total hip arthroplasty.

In 711 consecutive total hip arthroplasty operations, approximately 80% of patients were followed one to 7 years. Per priman operations outnumbered hips having had previous operations 511 to 200. The incidence of infection was higher in the hips having had previous operations (1.6 vs 3.5%). The overall incidence of deep infection was 16/711, or 23%. Analysis of the influences of operating room environment and preventative antibiotics revealed that there was a marked decrease in the attack rate of deep infection (7.6 vs 0.6%) when the Clean Room, personnel-isolator system, and preventative antibiotics were used. Reduced intraoperative wound bacterial contamination is accompanied by a reduced incidence of sepsis.