Microorganisms In Mice Research Articles

Stability of Resistance Induced by Escherichia coli in Comparison with That Carried by Clinical Isolates In Vivo

This study was conducted to investigate the stability in experimentally induced resistance in sensitive Escherichia coli for comparison with clinical resistant strains of the same microorganism so the first step was collected of 14 strains of E.coli from different disease cases: diarrhea (children= 6, calve= 3, poultry= 1), UTI (urine= 2), mastitis (milk= 2). And identificated these strains by using biochemical tests.These strains were divided to sensitive and resistant strains to cefquinome (β-lactam antibacterial) according to the results of sensitivity test (Agar well diffusion method). The minimum inhibitory concentration (MIC) by tube dilution method (TDM) was estimated to 8 selected strains (4 sensitive and 4 resistance) for comparison. The MIC values for sensitive strains were 0.007, 0.003, 0.017 and 0.005 µg/ml, for resistant strains were 372, 400, 42 and 25 µg /ml for cefquinome respectively. The second step was to induce resistance to sensitive strains in vitro by exposing the microorganisms to sub inhibitory concentration (1/4 MIC) of antibacterial for 14 passages through which the bacteria was reidentified by using a differential media to exclude any contamination.The new MIC values were 1.25, 0.8, 2.0 and 1.5 µg/ml for cefquinome respectively. The comparison method was employed to study the degree of stability of resistance in sensitive and resistant strains against this drug are in vivo by multiple injections (three times) of standard suspension test microorganisms in mice followed by reisolation and reidentification from liver. The mean of drop MIC value for sensitive strainswas 10.34 folds, and for resistant strains was increase in1.40folds for cefquinome, which represent statistically significant a drop in the values of MIC for sensitive strains but in the resistant strains not significant because a slight elevation in the values of MIC.

Infectious microorganisms in mice (Mus musculus) purchased from commercial pet shops in Germany

In this study, we investigated the prevalence of infectious microorganisms (viruses, bacteria, fungi and eukaryotic parasites) in mice from different pet shops in Germany; such animals may compromise the hygienic integrity of laboratory animal vivaria if private pet holders act as unintended vectors of infections carried by them. House mice sold as pets or feed specimens were purchased from different pet shops and tested for a comprehensive panel of unwanted microorganisms. We found a number of microorganisms in these pet shop mice, the most prevalent of which were Helicobacter species (92.9%), mouse parvovirus (89.3%), mouse hepatitis virus (82.7%), Pasteurella pneumotropica (71.4%) and Syphacia species (57.1%). Several microorganisms (e.g. mouse parvovirus, Theiler's murine encephalomyelitis virus, pneumonia virus of mice, Encephalitozoon cuniculi, Clostridium piliforme) had considerably higher prevalences than those reported in similar studies on wild mice from North America, Europe or Australia. Our study shows that direct contact with pet shop mice may constitute a risk for laboratory animal vivaria if hygienic precautions are not taken. However, even relatively simple precautions seem effective enough to hold the risk at bay.

Dietary cholesterol lowers plasma and cecal equol concentrations in mice

This study examined the effects of cholesterol on mouse intestinal microflora and on isoflavonoids in the cecum and plasma. Dietary cholesterol affects bile acid metabolism and bile acids can influence the intestinal microorganisms. Intestinal microflora appear to play an important role in isoflavone metabolism. We hypothesized that dietary cholesterol changes the metabolism of isoflavonoids and intestinal microorganisms in mice. Male mice were randomly divided into two groups, which were fed a cholesterol-daidzein (CDA) or daidzein (DA) diet (control diet) for 60d. Plasma equol and cecal equol concentrations were significantly higher in the DA group (control group) than in the CDA group. However, plasma cholesterol concentrations were significantly higher in the CDA group compared to the DA group. The composition of cecal microorganisms differed between the two dietary groups. The occupation ratios of Clostridium cluster XI, Clostridium subcluster XIVa, and Lactobacillales were significantly higher in the CDA group. The occupation ratio of Bifidobacterium was significantly lower in the CDA group. This study suggests that dietary cholesterol has the potential to affect the metabolism of equol from daidzein by altering the metabolic activity of the intestinal microorganisms and gut physiological function.

Oral Ingestion of Phosphorylated Dextrin Stimulates Antibody Responses in Mice

Corn dextrin with an average degradation degree of 16.7, or molecular mass of 2,700, was covalently introduced with 4.5 mol of phosphoric acid per mole by dry-heating with sodium phosphate. The effect on immunoglobulin production of the phosphorylated dextrin in mice that orally ingested lipopolysaccharide (LPS) from Salmonella typhimurium was investigated. No significant difference in body weight gain was observed between mice fed a phosphorylated dextrin-containing diet and those fed a control (dextrin-containing) diet. Fecal and intestinal anti-LPS immunoglobulin (Ig) A, intestinal and serum anti-LPS IgG, and fecal and intestinal total IgA levels were significantly higher in the mice given the phosphorylated dextrin. In contrast, serum and intestinal levels of IgM specific to the LPS were similar between the two groups. Moreover, spleen cells from mice fed the phosphorylated dextrin-added diet had significantly higher levels of anti-LPS IgG and IgA than those from mice on the control diet. These results suggest that dietary phosphorylated dextrin protects against local and systemic invasions of pathogenic microorganisms in mice.

Structural and ultrastructural studies of the urinary tract of mice inoculated with Lactobacillus fermentum.

To assess, using structural and ultrastructural studies of the urinary tract, the effects of the intraurethral inoculation of lactobacilli (probiotic treatment) as lactobacilli are the predominant micro-organisms of the urogenital tract of humans, monkeys and mice. Previous work showed the protective effect of Lactobacillus fermentum CRL 1058 intraurethrally inoculated against the challenge of uropathogenic Escherichia coli. There was also an effect of oestrogens and antibiotics in the kinetics of colonization of both micro-organisms in mice. In the present study L. fermentum was inoculated with agarose beads (107 colony-forming units) and the number of micro-organisms determined by plating in selective media, giving a high degree of colonization in all the organs studied. The urinary tract organs were processed by histological and electron microscopy techniques standardized in our laboratory. The intraurethral inoculation of lactobacilli produced no adverse effects or significant changes in any of the organs assessed (kidney, ureter, bladder or urethra), when evaluated by histological and ultrastructural techniques. The use of lactobacilli as a probiotic treatment is probably safe.

Safety evaluation of a polymerized hemoglobin solution in a murine infection model

Several investigators have observed that free hemoglobin may increase the mortality rate in experimental Escherichia coli peritonitis in animals. This effect is probably mediated by the heme moiety of hemoglobin, but the mechanism remains controversial. Free hemoglobin might impair neutrophil function, and it might serve as a source of iron, which is necessary for bacterial replication. Several modified hemoglobin solutions, developed as blood substitutes, are currently being tested in clinical studies, but concern exists that these solutions may have the potential to exacerbate a bacterial infection. At the Central Laboratory of the Netherlands Red Cross Blood Transfusion Service, a blood substitute based on modified hemoglobin (PolyHbXI) has been developed that has improved oxygen affinity and prolonged vascular retention. In the present study the potential risk of this solution on the promotion of infections has been evaluated. PolyHbXl was intravenously injected into mice in a clinically relevant dose of 1.5 gm/kg body weight 1 hour before intravenous administration of a sublethal number of Listeria monocytogenes, Salmonella typhimurium, E. coli, or Candida albicans organisms. PolyHbXl did not promote the proliferation of any of these microorganisms in the liver and spleen, nor did it lead to an increased mortality rate in the mice. Also, the in vitro proliferation of L. monocytogenes, S. typhimurium, and E. coli was not increased by PoIyHbXI. In conclusion, PoIyHbXI does not affect the course of infection with various microorganisms in mice, and no indication was found that this new blood substitute compromises the host defense against infections.

Protective immunity induced by low-virulence Candida albicans: Cytokine production in the development of the anti-infectious state

A low-virulence, agerminative strain of Candida albicans (PCA-2) is able to confer a high degree of nonspecific protection against subsequent challenge with highly virulent microorganisms in mice. In an attempt to better define the effect of PCA-2 vaccination on the immune system and the nature of the mechanisms involved in this protective state, we evaluated the pattern and kinetics of production of selected cytokines in PCA-2-treated mice. Thus, granulocyte/monocyte colony-stimulating factor (GM-CSF), tumor necrosis factor-α (TNF-α), interferon-γ (IFN-γ), and interleukin 1 (IL-1) were measured in the sera and spleen cell supernatants of vaccinated mice. In both cases, high levels of CSF, TNF, IL-1, and IFN were found 6 hr after PCA-2 infection and persisted for many days. There was always a correlation between the ability of PCA-2 to induce antimicrobial protection in vivo and its ability to cause cytokine production in vitro. Supernatants of splenocyte cultures from PCA-2-infected animals possessed macrophage-activating activity, as measured in microbiological assays. These data suggest an important involvement of cytokines in the nonspecific anti-infectious immunity induced by PCA-2, and also suggest a crucial role for IL-1 as an endogenous adjuvant in the initiation of the immune response to PCA-2.