Lactic acid bacteria isolated from young calves--characterization and potential as probiotics.

Lactic acid bacteria (LAB) are widely used as probiotics in humans and animals to restore the ecological balance of different mucosa. They help in the physiological functions of newborn calves that are susceptible to a variety of syndromes. The criteria for the selection of strains for the design of probiotic products are not available. Based in the host-specificity of the indigenous microbiota, 96 LAB isolates from faeces and oral cavity of calves were obtained. The surface properties were screened showing a small number of highly hydrophobic or autoagglutinating isolates. Also, a group produced H(2)O(2) and were able to inhibit pathogens, and two strains were bacteriocin-producers. Some grew at very low pH and high bile concentrations. The strains sharing some of the specific properties evaluated were identified genetically, assayed their compatibility and exopolysaccharide production. The results allow going further in the establishment of criteria to select strains to be included in a multi-strain-probiotic-product to be further assayed in animals.

Aryloxoalcanoic compounds induce resistance to antibiotic therapy in urinary tract infection caused by Escherichia coli.

Clofibric acid (CL) is a compound used to control hypertriglyceridemia, and ethacrynic acid (ET) is administered to enhance diuresis. These compounds are structurally analogous to the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), as they have a chlorinated phenoxy moiety. As these agents are mainly excreted by the renal route, they could potentially coexist with Escherichia coli in the urinary tract of infected patients. Induction of the in vitro resistance of E. coli to hydrophilic antibiotics was determined by increasing the values of the minimum inhibitory concentration (2-40-fold). These results correlated with drastically inhibited expression of the hydrophilic bacterial channel OmpF. In vivo assays were performed in ascending urinary tract infection in female BALB/c mice. Treatment with the hydrophilic antibiotic cephalexin 25 mg kg(-1) day(-1) by the oral route diminished renal infection. The CFU mean values in the kidneys were between 75% and 89% lower than those in animals without treatment. Simultaneous exposure to CL (at a therapeutic dose, 28.6 mg kg(-1) day(-1)) did not change the effect of the treatment. In contrast, ET at 2.9 mg kg(-1) day(-1) or 2,4-D at 70 mg kg(-1) day(-1) inhibited the antibiotic therapeutic effect. Moreover, 2,4-D dramatically increased bacterial infection after 9 days of exposure.

Clofibric and ethacrynic acids prevent experimental pyelonephritis by Escherichia coli in mice.

Interfering Escherichia coli attachment to the urinary tract, using P-fimbriation inhibitors, can prevent pyelonephritis. Clofibric and ethacrynic acids are organic compounds structurally related, but with different pharmacological uses. These agents are potentially active in the urinary tract due to its elimination in an unaltered form by the renal route. This study described a pyelonephritogenic E. coli strain, grown in the presence of sub-inhibitory concentrations of clofibric or ethacrynic acids (0.1 and 1 mM, respectively), which exhibits inhibition of P1 erythrocytes agglutination and a drastic decrease in fimbriation, using electron microscopy and quantitative analyses of superficial proteins (decrease to a 17-25% in comparison with the control). In vivo assays were performed using ascending urinary tract infection in mice. The treatment with therapeutic doses of the drugs, administered 2 days before the bacterial challenge and daily until the end of the experiment (22 days), abolished renal infection after 7-10 days of drug exposure. Within this period clofibric acid did not produce adverse effects on the renal parenchyma. However, ethacrynic acid caused pyelitis and tubular cellular desquamation. These results suggested that clofibric acid might be useful in the short-term prophylaxis of urinary tract infection.

Effect of the herbicide 2,4-dichlorophenoxyacetic acid on uropathogenic Escherichia coli virulence factors.

The effects of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D)-widely used in the world and mainly excreted by the renal route in exposed humans-were studied on the virulence and surface characteristics of an uropathogenic Escherichia coli strain. When the urine was supplemented with 2,4-D in vitro, the compound significantly reduced the bacterial fimbriation assayed by hemagglutination and surface protein quantification. Protein values decreased from 0.24 mg/g dw to 0.05 or 0.12 mg/g dw by 1 or 0.1 mM 2,4-D treatment, respectively. The effects in vivo were studied in groups of mice challenged intra-urethra with E. coli and exposed by the oral route with three different 2,4-D doses (2.6, 25 or 70 mg/kg bw) during 22 days. Depending on the dose used, the herbicide significantly decreased or removed bacterial cells in mice bladder and kidneys; except in the group treated with the highest dose from the 9th day of treatment. The histological studies showed mononuclear cell infiltration at low doses, and toxic damage in the renal parenchyma at prolonged exposure with higher doses, up to tisular necrosis in the 70 mg/kg bw group after 9 days of treatment. Our investigations performed in an experimental model suggest that short time 2,4-D exposure at low doses could act in prevention of UTI stimulating leukocytic migration and decreasing bacterial fimbriation. On the contrary, high doses and long-term exposure enhanced renal damage resulting in infection recurrence.