Prevalence of anti-Toxoplasma gondii and anti-Neospora caninum antibodies in sheep from Mossoró, Rio Grande do Norte, Brazil

Toxoplasma gondii is an obligate intracellular parasite with a variety of hosts, responsible for reproductive problems and economic losses in sheep flocks. Neospora caninum was recently identified and its clinical presentation in sheep is similar to that of toxoplasmosis, which can cause repeated abortions, though less frequently in this species. In order to confirm the prevalence of these agents in the city of Mossoró, Rio Grande do Norte, Brazil, 409 serum samples from adult sheep (364 females and 45 males) were tested by the indirect immunofluorescence antibody test, using cut-off point at a dilution of 1:64 and 1:50 for T. gondii and N. caninum, respectively. From the 35 properties examined, 23 (65.7%) had at least one seropositive animal for T. gondii and six (17.1%) for N. caninum. The prevalence of seropositive animals for T. gondii was 20.7% and for N. caninum 1.8%. There was no association between the presence of the agent’s antibody and gender, reports of reproductive problems and presence of dogs and/or cats in the properties. T. gondii is well distributed and N. caninum has low prevalence in sheep and in the properties of the studied region.     

Physiological responses to water restriction in dry and lactating Awassi ewes

The effect of water restriction in Awassi ewes was assessed under two physiological conditions: lactating and dry, over a 3-week-period (August–September, 2002). Eight dry and eight lactating Awassi ewes (with their lambs) were assigned to one of two watering regimes: watered once every three days and daily watering, respectively. Weather data, body weight and rectal temperature were recorded. Venous blood was sampled on the watering day of the water-restricted group, and subjected to haematological, biochemical and electrolytes analysis. Ewes under water restriction lost more weight and had higher packed cell volume, haemoglobin, serum cholesterol, urea, creatinine, total protein and albumin as compared to daily-watered animals. However, lactation seemed to have no significant effect on these serum components. As for blood pH and electrolytes, Na⁺ and Cl⁻ were significantly higher under water restriction; whereas significantly lower K⁺ and Ca⁺⁺ but higher pH and Cl⁻ were observed in lactating animals. Finally, lower cortisol concentrations were observed in water-restricted animals, warranting further studies on the hormonal adaptation to long term water stress. It was concluded that water restriction induces similar changes in blood physiological indicators in dry and lactating Awassi ewes; while lactation beyond the first month post partum seems to mostly affect blood electrolytes.     

Green tea flavan-3-ols and oligomeric proanthocyanidins inhibit the motility of infective larvae of Teladorsagia circumcincta and Trichostrongylus colubriformis in vitro

The effects of a hot water infusion and an aqueous acetone extract of green tea (Camellia sinensis) on the motility of infective larvae of the sheep nematodes Teladorsagia circumcincta and Trichostrongylus colubriformis were investigated under in vitro conditions. The infusion and extract dose-dependently inactivated the infective larvae as assessed by the larval migration inhibition (LMI) assay. To determine the components responsible for the inhibitory activity, the hot water infusion and aqueous acetone extract of green tea were fractionated on Sephadex LH-20 and the green tea extract fractions (GTE-I-VIII) characterised by mass spectrometry. The larvae were exposed to increasing concentrations of these GTE fractions. Fractions containing epigallocatechin gallate (EGCG) and proanthocyanidin oligomers were most effective. GTE fractions were more effective against T. circumcincta than T. colubriformis larvae as assessed by the LMI assay.     

ermB-mediated erythromycin resistance in Streptococcus uberis from bovine mastitis

The ermB gene was identified in 111 erythromycin resistant isolates of Streptococcus uberis from cases of bovine mastitis associated either with a constitutive (47/111) or an inducible (64/111) phenotype, as well as a phenotypic resistance to all macrolides tested. Resistance to lincosamides was identified in 14 other isolates of S. uberis from bovine mastitis cases and was mainly mediated by the linB gene; resistance conferred by a combination of two genes (linB–lnuD, ermB–linB) was also detected.     

Identification of the tet(B) resistance gene in Streptococcus suis

The tetracycline resistance gene, tet(B), has been described previously in Gram negative bacteria. In this study tet(B) was detected in plasmid extracts from 17/111 (15%) Streptococcus suis isolates from diseased pigs, representing the first report of this resistance gene in Gram positive bacteria.     

Effect of bacitracin on tetracycline resistance in Escherichia coli and Salmonella

Tetracyclines and bacitracin are used extensively as a growth promotant and a therapeutic, respectively in livestock. In this study, we test whether there is an interaction between bacitracin and tetracycline that can select for an increase in microbial tetracycline sensitivity, using Escherichia coli and Salmonella as a model. We found via in vitro studies that bacitracin at sublethal concentrations preferentially selects for outgrowth of tetracycline-sensitive bacteria from among a population of tetracycline-resistant and tetracycline-sensitive E. coli and Salmonella strains. Most of the bacterial strains employed in our study were shown by PCR to possess the tetracycline resistance gene tet(A) or tet(C), either of whose activity is associated with tetracycline efflux. Bacitracin could be substituted for the lipophylic chelator, fusaric acid, used as a positive selective agent for tetracycline sensitivity. Together, these observations suggest that bacitracin-mediated selection for tetracycline sensitivity alters the function of tetracycline efflux proteins. Using bacitracin and tetracycline simultaneously may improve the effectiveness of the antibiotics, while decreasing the risk of selecting for a population of tetracycline-resistant microorganisms.     

Enhanced resistance to Listeria monocytogenes in mice injected with either whole cells or fractions of the aerobic corynebacterium, Corynebacterium catarrhalis

Resistance of mice to Listeria monocytogenes was shown to be enhanced by pretreatment with either intact or delipidated whole cells of a new species of aerobic corynebacteria, designated as Corynebacterium catarrhalis, as well as with fractions isolated therefrom. Both whole cells and a particulate fraction (CBAp40) proved to be effective when given intravenously, whereas a water-soluble fraction (CBA-LS) was not. In contrast, CBA-LS, as well as CBAp40 and whole cells were found to be effective when given subcutaneously as far as they had previously been adsorbed onto a gel of either calcium phosphate or aluminum hydroxide. Furthermore, pretreatment of mice with either of the mineral gels in the absence of the products failed to confer protection on them to the challenge with L. monocytogenes. It is suggested that C. catarrhalis or products derived therefrom could be used as agents for enhancing resistance to infections of immuno-compromised individuals.     

Seroprevalence of Toxoplasma gondii infection in sheep and alpacas (Llama pacos) in Chile

Serum samples from 408 sheep from different regions of Chile and 447 alpacas (Llama pacos) from the north of the country were tested for Toxoplasma gondii antibodies. The indirect haemagglutination test (IHAT) was used in both species and the indirect immunofluorescence test (IIFT) was also used on the sheep samples in order to compare the performance of the tests in that species. In both tests, titers ≥1:16 were considered diagnostically significant. Sera from 49 sheep (12%) were positive to T. gondii antibodies by the IHAT. When using the IIFT, 114 sheep sera (28%) were positive. The different results obtained in sheep sera between the tests were significant (p<0.0001). No differences were observed between geographical locations or sex of the sampled sheep regarding serological detection of T. gondii antibodies in sheep. As expected, adult sheep showed higher T. gondii reactivity than young sheep (p=0.0008). The corrected prevalence of toxoplasmosis in alpaca was 16.3% (32 positive out of 447). The rather low prevalence in alpacas may be associated with their extensive management as well as the extreme climatic conditions of The Andes which apparently would not be favorable for the transmission of the parasite.     

Seroprevalence of antibodies to Encephalitozoon cuniculi and Encephalitozoon intestinalis in humans and animals

The presence of antibodies against Encephalitozoon cuniculi (E. cuniculi) and Encephalitozoon intestinalis (E. intestinalis) was examined in 215 samples from humans and in 488 samples from five different species of domestic and companion animals in Slovakia. The 215 human samples and samples from 90 swine, 123 non-infected cattle (cattle), 24 cattle infected with bovine leukosis virus (BLV-positive cattle), 140 sheep and 111 dogs were examined by the enzyme-linked immunosorbent assay (ELISA). Samples with serum titres 1:200 or higher were considered as positive. Specific anti-E. cuniculi antibodies were found in humans (0.9%), swine (52%), cattle (2%), sheep (9%) and dogs (15%) except for the BLV-positive cattle at the titre of 1:200. The titre of 1:400 was detected only in humans (0.5%). The presence of specific anti-E. intestinalis antibodies at the titre of 1:200 was confirmed in humans (6%), swine (51%), cattle (11%), BLV-positive cattle (13%) and dogs (6%) but not in sheep. The anti-E. intestinalis antibodies reached the 1:400 in humans (1%), swine (4%) and BLV-positive cattle (17%). The presence of specific anti-E. intestinalis antibodies at the titre of 1:600 was observed only in one swine (1%). Significant differences were observed in animals at titres 1:200 and 1:400 (chi-squared test: p < 0.0001) for both pathogens and in humans only for E. cuniculi at the titre of 1:400 (chi-squared test: p < 0.0075).     

Comparison of two versions of larval development test to detect anthelmintic resistance in Haemonchus contortus

Larval development (LDT) and micro-agar larval development tests (MALDT) were used to compare the reliability and sensitivity of two methods for detecting anthelmintic resistance in Haemonchus contortus. The tests were conducted using three resistant and four susceptible isolates of H. contortus. Both versions of the tests provided comparable results with regard to the characterization of benzimidazole and levamisole susceptibility but neither test was sufficiently sensitive to discrimination between an ivermectin (IVM) susceptible and an IVM resistant isolate. Each test has its own merits with the LDT having the advantage of being less time-consuming.     

Fractional protein synthesis rate and polyamine concentrations in tissues of Merino sheep selected for gastrointestinal nematode resistance

Selection of sheep for resistance to gastrointestinal nematodes has been considered as one option to control nematode infection. It is essential to understand the influence of selection on the diversification of protein metabolism in individual tissues. In this experiment we examined fractional protein synthesis rate (FSR) and polyamine (putrescine, spermidine and spermine) and histamine concentrations in tissues of Merino sheep selected for low faecal worm egg count (parasite resistance) and control sheep. Sixty 18-month-old Merino rams, 40 from the resistant flock and 20 from the control line, were kept in individual pens of an animal house and fed ad libitum. Half of each genotype group were dosed orally with infective larvae of Trichostrongylus colubriformis and Ostertagia circumcincta thrice weekly to deliver 10,000 larvae from each species per week for 18 weeks. At the end of week 18, FSR was measured using a flooding dose of l-[ring-d₅]phenylalanine, and polyamine concentrations were determined in all the sheep. Regardless of sheep genotype, the nematode infection significantly increased FSR in the mesenteric lymph nodes (37.0% vs. 32.6%/day, P < 0.01) and abomasal lymph nodes (28.8% vs. 16.0%/day, P < 0.001) and the bone marrow (5.12% vs. 3.96%/day, P < 0.01), but reduced FSR in skin (17.4% vs. 20.6%/day, P < 0.001), muscle (2.46% vs. 2.73%/day, P < 0.05) and liver (24.1% vs. 25.8%/day, P < 0.05). Nematode infection did not affect FSR in the jejunum. Polyamine concentrations in the tissues were generally increased by the infection (P < 0.05) except for a decline in spermine concentration in the muscle (P < 0.01). Overall there was no significant effect of selection for nematode resistance on tissue FSR or the concentration of amines. It was concluded that nematode infection resulted in a divergence of protein synthesis between tissues, and selection for nematode resistance in Merino sheep did not result in significant change in tissue protein synthesis compared with control sheep.     

The Effect of Anthelmintic Capsules on the Egg Output and Larval Viability of Drug-resistant Parasites

Challenge with an equal mix of drug-resistant and drug-susceptible larvae of Teladorsagia circumcincta resulted in infections in groups of lambs (n = 6) either untreated or given controlled-release capsules, containing either albendazole or ivermectin. Lambs treated with albendazole capsules contained similar numbers of adult worms at necropsy to the other groups but had no detectable faecal egg count. Animals treated with ivermectin capsules had similar worm burdens and faecal egg counts to the control group but the worms had significantly higher numbers of eggs in utero. These results provide evidence for suppression of egg production by both anthelmintic treatments. The observation that albendazole caused a significant reduction in the developmental success of parasite eggs also has implications for the use of faecal egg count as an indicator for pasture contamination with resistant parasites. In two further groups of lambs, either untreated or given albendazole capsules, treatment caused a significant reduction in egg count and adult worm burden of Trichostrongylus colubriformis. No significant effects were observed on in utero egg counts or egg viability and the apparent effect on the number of eggs produced in faeces per adult female was not significant (p = 0.077). There was, therefore, no evidence that albendazole controlled-release capsules caused suppression of egg output in this species.     

Effect of Momordica charantia L. in the resistance to aminoglycosides in methicilin-resistant Staphylococcus aureus

In this study the ethanol extract (EEMC) of Momordica charantia L. (Cucurbitaceae) was tested for its modifying antibiotic activity against a MRSA strain. The growth of an MRSA (SA358) in the absence and presence of aminoglycosides was evaluated. A potentiating effect between this extract and all aminoglycosides was demonstrated. Similarly, the same effect was shown by chlorpromazine on kanamycin, gentamicin and neomycin, indicating the involvement of an efflux system in the resistance to these aminoglycosides. Extracts from M. charantia could be used as a source of plant-derived natural products with resistance-modifying activity. This is the first report about the modifying antibiotic activity of M. charantia, constituting a new weapon against multi-resistant bacteria such as MRSA.     

In vitro antagonistic activities of Lactobacillus spp. against Brachyspira hyodysenteriae and Brachyspira pilosicoli

The sensitivity of Brachyspira hyodysenteriae and Brachyspira pilosicoli, respectively the causative agents of Swine Dysentery and Porcine Intestinal Spirochaetosis to two probiotic Lactobacillus strains, L. rhamnosus CNCM-I-3698 and L. farciminis CNCM-I-3699 was studied through viability, motility and coaggregation assays. The cell-free supernatant of these lactobacilli contains lactic acid, that is stressful for Brachyspira (leading to the formation of spherical bodies), and lethal. It was demonstrated for the first time the in vitro coaggregation properties of two probiotic Lactobacillus strains (active or heat-treated) with two pathogenic strains of Brachyspira, leading to (1) trapping of spirochaetal cells in a physical network as demonstrated by SEM; (2) inhibition of the motility of Brachyspira. Such in vitro studies should encourage in vivo studies in animal model to evaluate the potential of the use of probiotic lactobacilli through a feeding strategy for the prevention of B. hyodysenteriae and B. pilosicoli.     

Anaplasma marginale infection in a Japanese Black cow 13 years after eradication of Rhipicephalus (Boophilus) microplus in Okinawa, Japan

In October 2007, a 15-year-old Japanese Black cow on Ishigaki Island, Okinawa, Japan, was diagnosed with Anaplasma marginale infection based on clinical symptoms, blood examination, smear observation, 16S rRNA and groEL gene sequence analysis, and the result of a CF test. The cow was introduced into the farm from mainland Japan as a calf in 1993, one year before the eradication of Rhipicephalus (Boophilus) microplus, the main vector of A. marginale in Okinawa Prefecture. It is possible that the cow was first infected with A. marginale as a calf in Ishigaki Island and had been persistently infected since then. This is the first reported clinical case of A. marginale infection of cattle since the eradication of R. microplus in Okinawa Prefecture. Additional analysis of major surface protein 1α amino acid sequences revealed that the A. marginale Okinawa strain presented four new repeat forms which were not seen in other strains. This indicates that the Okinawa strain may be a unique geographical variant of A. marginale.     

Multiple anthelmintic resistance and the possible contributory factors in Beetal goats in an irrigated area (Pakistan)

This paper presents the first report of multiple anthelmintic resistance in the gastrointestinal nematodes of goats and its possible contributory factors in an irrigated area (Pakistan). A total of 18 privately owned Beetal goat flocks were selected in order to determine the anthelmintic resistance against commonly used anthelmintics. Forty to 48 animals from each flock were selected according to their weight and egg count. The three anthelmintics viz., oxfendazole, levamisole and ivermectin, were given to three groups at manufacturer’s recommended dose while one group was kept as untreated control. Anthelmintic resistance was determined through faecal egg count reduction and egg hatch tests while assessment of the contributory factors of anthelmintic resistance was measured through the rural participatory approach. Faecal egg count reduction test revealed high prevalence of anthelmintic resistance (83.3%) and it was either single (levamisole) or multiple (oxfendazole and levamisole). Egg hatch test confirmed the resistance against oxfendazole as detected with faecal egg count reduction test. None of the goat flocks was resistant to ivermectin. Copro-cultures revealed that Haemonchus contortus, Trichostrongylus colubriformis and Teladorsagia circumcincta were the most common species exhibiting resistance to levamisole and oxfendazole. Step-wise logistic regression of the data on worm control practices revealed significant role of under-dosing, low-protein diets, healthcare supervision by the traditional healers and mass treatments.     

Diagnosis by culture and PCR of Salmonella Abortusovis infection under clinical conditions in aborting sheep in Switzerland

Since 2003 eleven Swiss sheep flocks were affected by abortion storms due to Salmonella abortusovis, an infection which had not been reported in this country for decades although cases of salmonellosis are notifiable in Switzerland. This raised doubts about the adequacy of the currently used diagnostic tools and the origin of this infection. Therefore, PCR was tested for its potential as a more rapid and more reliable method for diagnosing S. abortusovis infections under field conditions. Fecal and vaginal samples were collected at different times after abortion and PCR was used to detect bacterial DNA. Bacteria were isolated by conventional culture techniques. For determining their origin they were analyzed by pulsed field gel electrophoresis (PFGE) and compared to isolates from Germany and France. Sequencing of randomly selected amplicons allowed confirming the specificity of the result. PCR was more sensitive because it allowed detecting S. abortusovis DNA up to three months after infection even in samples that were negative by culture. Escherichia coli from the digestive tract of sheep could inhibit the growth of S. abortusovis in vitro suggesting that the lower sensitivity of diagnosis by bacterial culture may in part be due to growth inhibition of S. abortusovis by resident bacteria. Results of PFGE indicated that the Swiss strains were closely related among themselves but distinct from German and French strains suggesting the presence of an autochthonous infection.     

Phylogentic analysis of Anaplasma ovis strains isolated from sheep and goats using groEL and mps4 genes

Evidence of Anaplasma spp. in goats and sheep in Cyprus has been demonstrated by previous research. Herein, further research was performed for the identification of the exact Anaplasma spp. resulting in the identification of Anaplasma ovis strains in all samples examined. We used a bioinformatics as well as a molecular approach (study of groEl and mps4 genes) in order to verify the validity of the results. All samples depicted the presence of A. ovis regardless of the host (goat or sheep).