Comparison of virulence gene profiles of Escherichia coli strains isolated from healthy and diarrheic swine

A combination of uni- and multiplex PCR assays targeting 58 virulence genes (VGs) associated with Escherichia coli strains causing intestinal and extraintestinal disease in humans and other mammals was used to analyze the VG repertoire of 23 commensal E. coli isolates from healthy pigs and 52 clinical isolates associated with porcine neonatal diarrhea (ND) and postweaning diarrhea (PWD). The relationship between the presence and absence of VGs was interrogated using three statistical methods. According to the generalized linear model, 17 of 58 VGs were found to be significant (P < 0.05) in distinguishing between commensal and clinical isolates. Nine of the 17 genes represented by iha, hlyA, aidA, east1, aah, fimH, iroN(E).(coli), traT, and saa have not been previously identified as important VGs in clinical porcine isolates in Australia. The remaining eight VGs code for fimbriae (F4, F5, F18, and F41) and toxins (STa, STh, LT, and Stx2), normally associated with porcine enterotoxigenic E. coli. Agglomerative hierarchical algorithm analysis grouped E. coli strains into subclusters based primarily on their serogroup. Multivariate analyses of clonal relationships based on the 17 VGs were collapsed into two-dimensional space by principal coordinate analysis. PWD clones were distributed in two quadrants, separated from ND and commensal clones, which tended to cluster within one quadrant. Clonal subclusters within quadrants were highly correlated with serogroups. These methods of analysis provide different perspectives in our attempts to understand how commensal and clinical porcine enterotoxigenic E. coli strains have evolved and are engaged in the dynamic process of losing or acquiring VGs within the pig population.

Palm kernel meal in broiler diets: effect on chicken performance and health

An increase in the production of palm kernel meal (PKM) coupled with the concern for continued availability of conventional feedstuffs in some parts of the world has led to research to establish the maximum inclusion level of palm kernel meal in broiler diets. The results suggested that palm kernel meal has no anti-nutritional properties and thus its inclusion is safe up to at least 40% in the diet, provided the diet is balanced in amino acids and metabolisable energy. Although feed digestibility is decreased due to high dietary fibre when PKM is included in the diet, the feed intake is increased. This makes total digestible nutrient intake relatively high. beta-mannan is the main component of palm kernel meal non-starch polysaccharide (NSP). Both mannose and manno-oligosaccharides have been reported to act as prebiotics. The inclusion of palm kernel meal in the diet improves the immune system of birds and reduces pathogenic bacteria and increases the population of nonpathogenic bacteria in the intestine. These two benefits should be considered as strong recommendations for using palm kernel meal in broiler diets, particularly in palm kernel meal producing countries, not only for increasing bird productivity but also to improve chicken health. Selective enzyme addition increases feed efficiency and digestibility as well as decreasing the moisture content of faeces.

The asymptomatic bacteriuria Escherichia coli strain 83972 outcompetes uropathogenic E-coli strains in human urine

Escherichia coli is the most common organism associated with asymptomatic bacteriuria (ABU). In contrast to uropathogenic E. coli (UPEC), which causes symptomatic urinary tract infections (UTI), very little is known about the mechanisms by which these strains colonize the human urinary tract. The prototype ABU E. coli strain 83972 was originally isolated from a girl who had carried it asymptomatically for 3 years. Deliberate colonization of UTI-susceptible individuals with E. coli 83972 has been used successfully as an alternative approach for the treatment of patients who are refractory to conventional therapy. Colonization with strain 83972 appears to prevent infection with UPEC strains in such patients despite the fact that this strain is unable to express the primary adhesins involved in UTI, viz. P and type 1 fimbriae. Here we investigated the growth characteristics of E. coli 83972 in human urine and show that it can outcompete a representative spectrum of UPEC strains for growth in urine. The unique ability of ABU E. coli 83972 to outcompete UPEC in urine was also demonstrated in a murine model of human UTI, confirming the selective advantage over UPEC in vivo. Comparison of global gene expression profiles of E. coli 83972 grown in lab medium and human urine revealed significant differences in expression levels in the two media; significant down-regulation of genes encoding virulence factors such as hemolysin, lipid A, and capsular pollysaccharides was observed in cells grown in urine. Clearly, divergent abilities of ABU E. coli and UPEC to exploit human urine as a niche for persistence and survival suggest that these key differences may be exploited for preventative and/or therapeutic approaches.

Relationship between bicarbonate retention and bone characteristics in broiler chickens

Determination of the bicarbonate retention factor (BRF) is an important step during development of the indicator amino acid oxidation technique for use in a new model. A series of 4-h oxidation experiments were performed to determine the BRF of broilers aged 7, 14, 21, 28, 35, and 42 d using 4 birds per age group. A priming dose of 1.2 mu Ci of (NaHCO3)-C-14, followed by eight half-hourly doses of 1 mu Ci of (NaHCO3)-C-14 were given orally to each of 4 birds per age. The percentage of 14 C dose expired by the bird at a steady state was measured. These birds, as well as 12 additional birds matched for age and BW, were killed, and femur bone mineral density was measured by quantitative computed tomography to determine the relationship between bone development and bicarbonate retention at each age. There was a correlation (r = 0.50; P < 0.05) between total cross-sectional femur bone mineral density and bicarbonate retention at each age. A prediction equation (Y = 6.95 x 10(-2) X - 3.51 x 10(5)X(2) + 27.58; P < 0.0001, R-2 = 0.79) where Y = bicarbonate retention and X = BW was generated to predict Y as a function of X. Bicarbonate retention values peaked at 28 d, during the stage of the most rapid bone deposition and the highest growth rate. A constant BRF was found from 1,900 to 2,700 g of BW of 35.15 +/- 1.095% (mean SEM). This retention factor will allow the accurate correction of oxidation of C-14-labeled substrates in broilers of different ages and BW in future indicator amino acid oxidation studies.

Total and ileal digestible tryptophan contents of feedstuffs for broiler chickens

Reliable values of total and digestible tryptophan in components of feed formulation matrices are needed because tryptophan is often the third limiting amino acid in practical poultry diets. However, tryptophan is oxidatively destroyed during acid hydrolysis in routine amino acid analysis and its determination requires a separate analytical procedure. The variability in contents and apparent ileal digestibility for 6-week-old broiler chickens of tryptophan in 74 samples representing 24 feedstuffs are presented in this paper. The average ileal tryptophan digestibility coefficient in wheat was 0.83, in sorghum and triticale 0.75, maize 0.71, soybean meal 0.84, sunflower meal 0.81, canola meal 0.78 and cottonseed meal 0.75. Among the grain legumes, tryptophan in lupins was better digested than that in chickpeas, fababeans and field peas. Among the animal protein meals, the tryptophan digestibility coefficients in fish meal (0.77) and blood meal (0.84) were substantially higher than those in meat meal (0.64), meat-and-bone meal (0.63) and feather meal (0.52). Marked variations in tryptophan digestibility were also observed among samples of fish meal, meat-and-bone meal and meat meal, highlighting significant batch-to-batch differences. For most feedstuffs, considerable variability was observed in the tryptophan concentrations, but such variations were not reflected in digestibility coefficients. (c) 2006 Society of Chemical Industry.

In vitro exposure of community-associated methicillin-resistant Staphylococcus aureus (MRSA) strains to vancomycin: does vancomycin resistance occur?

Vancomycin is the preferred parenteral antibiotic for the treatment of all methicillin-resistant Staphylococcus aureus (MRSA) infections, including the newly emerging community-associated MRSA (CA-MRSA) infections. Vancomycin-intermediate nosocomial MRSA strains have developed in vitro and in vivo after exposure to vancomycin. The aim of this study was to determine whether daily serial passage of CA-MRSA strains onto vancomycin-supplemented agar selects for the development of vancomycin resistance. Twelve clinical isolates of the six commonest Australian and US strains of CA-MRSA were serially passaged daily for 25 days onto brain-heart infusion agar plates supplemented with 4 mu g/mL vancomycin and then subcultured for a further 15 days onto antibiotic-free agar to assess the stability of the resistance phenotype. Minimum inhibitory concentrations (MICs) were determined by standard Etest every 5 days from day 0 to day 40. Serial passaging resulted in increased MICs in all strains but the rises were modest, with an increase of < 2 doubling dilutions. All strains remained vancomycin Susceptible throughout the experiment according to Clinical Laboratory Standards Institute criteria. Crown Copyright (c) 2005 Published by Elsevier B.V. on behalf of International Society of Chemotherapy. All rights reserved.

Prevalence of drug-resistance mutations and non-subtype B strains among HIV-infected infants from New York State

Summary: Prevalence studies indicate that transmission of drug-resistant HIV has been rising in the adult population, but data from the perinatally infected pediatric population are limited. In this retrospective study, we sequenced the pol region of HIV from perinatally infected infants diagnosed in New York State in 2001-2002. Analyses of drug resistance, subtype diversity, and perinatal antiretroviral exposure were conducted, and the results were compared with those from a previous study of HIV-infected infants identified in 1998-1999. Eight of 42 infants (19.1%) had provirus carrying at least 1 drug-resistance mutation, an increase of 58% over the 1998-1999 results. Mutations conferring resistance to nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors were detected in 7.1%, 11.9%, and 2.4% of specimens, respectively. Consistent with previous results, perinatal antiretroviral exposure was not associated with drug resistance (P = 0.70). Phylogenetic analysis indicated that 16.7% of infants were infected with a non-subtype B strain of HIV. It seems that drug-resistant and non-subtype B strains of HIV are becoming increasingly common in the perinatally infected population. Our results highlight the value of resistance testing for all HIV-infected infants upon diagnosis and the need to consider subtype diversity in diagnostic and treatment strategies.

Optimum inclusion of field peas, faba beans, chick peas and sweet lupins in poultry diets. II. Broiler experiments

1. Three experiments were undertaken to determine the optimum inclusion rates of held peas, faba beans, chick peas and sweet lupins in broiler starter and finisher diets in amounts up to 360 g/kg. 2. In experiment A chickens in cages grown to 21 d on diets with field peas and faba beans gave better growth rate and feed efficiency than those with sweet lupins and chick peas. Growth rate and Food conversion ratio (FCR) improved with increasing amounts of faba beans in the diet while for chick peas growth rate and FCR declined. Digesta viscosity and excreta stickiness scores were much higher on diets with sweet lupins. Steam pelleting improved growth rate and FCR on all diets. 3. In experiment B birds were in cages and grown from 21 to 42 d. There were no differences between grain legumes (when combined for all inclusions) for growth rate, food intake or FCR. Viscosity was again much higher on the sweet lupin-based diets while the pancreas was significantly enlarged on the diets with chick peas, as observed previously in chickens grown to 21 d. Steam pelleting of diets gave a consistent and positive response for weight gain and FCR. 4. Experiment C was carried out in pens each holding 60 birds under semi-commercial conditions and grown to 4 2 d on starter and finisher diets with the same grain legumes as used previously but each at 2 rates of inclusion similar to those in commercial practice. Field peas at 200 to 300 g/kg and chick peas at 150 to 220 g/kg gave inferior growth to faba beans (150 to 180 g/kg) and sweet lupins (120 g/kg). 5. The results of these experiments allowed tentative recommendations to be made to industry for inclusion rates of these cultivars of the 4 grain legumes. These were: field peas 300 g/kg; faba beans 200 g/kg, chick peas 100 g/kg and sweet lupins

The effect of xylanase, phytase and lipase supplementation on the performance of broiler chickens fed a diet with a high level of rice bran.

Enzyme products did not have a significant effect (P>0.05) on weekly fed intake and weight gain of birds. But feed intake tended to drop and weight gain tended to increase in response to supplementation of the three enzymes. Weight gain of the birds was increased by 0.6% with lipase, 3.7% with phytase and 2.4% with xylanase. Xylanase had a marked effect (P