The role of an early Salmonella Typhimurium infection as a predisposing factor for necrotic enteritis in a laboratory challenge model

Necrotic enteritis (NE) caused by Clostridium perfringens (CP) in poultry is an important bacterial disease in terms of economic implications. The disease is multifactorial and is invariably associated with predisposing factors. In the present experiments, we investigated the potential predisposing role of neonatal Salmonella Typhimurium (ST) infection for NE-associated mortality in a laboratory challenge model. In two experiments, day-of-hatch chicks were randomly assigned to four groups: Group 1, nonchallenged control; Group 2, chickens received Eimeria maxima (EM) and CP; Group 3, chickens received EM and CP and were also challenged with ST at day 1 of age; Group 4, chickens received EM and CP and were also challenged with ST at day 17 of age. Challenged groups received an oral dose of EM at 18 days of age and CP (10(8) colony-forming units/chick) at 22-23 days of age. When compared to EM and CP, chicks challenged with ST (day 1) had increased NE-associated mortality and CP-associated lesion scores (P < 0.05) in both experiments. Furthermore, body weight and body weight gain were lower (P < 0.05) in chicks infected with ST (day 1) in the first experiment, even though no differences (P > 0.05) were observed in weight gain in the second experiment. Chicks challenged with ST (day 17) were similar to the EM and CP group in all of the above-mentioned parameters, indicating that a paratyphoid infection in younger chicks remarkably alters the susceptibility to secondary bacterial infections. Based on this work, the authors suggest that an ST infection early in the age of a chick may be important for altering susceptibility to NE, an observation that may be useful from the perspective of experimental reproduction of this disease and, perhaps, as an economically important reason to address the problem of paratyphoid Salmonella infections in young chicks.     

Characterisation of colony-stimulating activity in the avian T cell-derived factor, Salmonella enteritidis-immune lymphokine

This investigation was designed to characterise the specific cytokine activity from the conditioned medium of concanavalin A-stimulated avian T cells derived from Salmonella enteritidis-immune chickens, S enteritidis-immune lymphokine (ILK). Studies were designed to determine first, whether colony-stimulating activity was present in ILK, second, the type(s) of colonies from the bone marrow that were supported in vitro by the potential colony-stimulating factors in ILK and, third, whether colony-stimulating activity was present in serum from chicks treated with ILK and challenged with S enteritidis, and to use physicochemical treatment as a means of identifying the potential colony-stimulating factor(s) in ILK. Both ILK alone and serum from chicks treated with ILK and challenged with S enteritidis caused significant increases in the number of colony-forming units (CFU) from the bone marrow in vitro. After 10 days of incubation, ILK alone supported the in vitro growth of granulocytic bone marrow colonies. The colony-stimulating activity from serum derived from chicks treated with ILK and challenged with S enteritidis peaked two hours after the challenge. When ILK was either heated at 100°C or treated with trypsin or acid and then injected into chicks, all the chicks responded with significant increases in circulating polymorphonuclear leucocytes (PMNS). However, when assayed for in vitro colony-stimulating activity, only trypsinisation destroyed the activity in ILK. The results indicate that a colony-stimulating factor which preferentially supported the growth of granulocytic bone marrow colonies was present in ILK and that the factor was stable to heat and acid but sensitive to trypsin.     

Effect of prolonged heat stress in single-comb white leghorn hens on progeny resistance to Salmonella enteritidis organ invasion.

In our laboratory, we have often had difficulty infecting neonatal chickens with invasive salmonellae when ambient temperatures exceed 30 C. We hypothesized that this increased resistance in chicks during warmer months may be associated with heat stress-associated maternal factors. Presently, single-comb white leghorn hens were separated into a non-heat-stressed group, reared under temperatures from approximately 10 to 24 C, and a heat-stressed group, in which environmental temperature was incrementally elevated to near 37 C and maintained for the duration of the 13-wk study. For Expt. 1, eggs from heat-stressed or control hens, collected on days 8-14 of the study, were pooled respective to treatment and incubated. At the time of egg collection, mean hen-day egg production was 51.83% or 65% for heat-stressed or control hens, respectively. On day of hatch, progeny from hens in each group were orally challenged with 0.9 x 10(4) colony-forming units (CFU) Salmonella enteritidis (SE). Rates of SE organ invasion of 97.3% or 94.4% were obtained in progeny from heat-stressed or control hens, respectively. In Expt. 2, eggs from heat-stressed or control hens from days 30-42 of the study were collected and pooled by treatment for incubation. Mean hen-day egg production was 46.5% or 72.85% for heat-stressed or control hens, respectively. On day of hatch, progeny were orally challenged with either 2.2 x 10(3) or 2.2 x 10(4) CFU SE. A 100% incidence in SE organ invasion was observed in all groups. In Expt. 3, eggs were collected from days 43 through 56 of the study. Mean hen-day egg production was 19.8% or 76.8% for heat-stressed or control hens, respectively. On day of hatch, progeny were orally challenged with 2 x 10(3) CFU SE. Rates of SE organ invasion of 95.8% or 95.6% were obtained in progeny from heat-stressed or control hens, respectively. These data suggest that factors other than elevated temperature may be responsible for seasonal resistance to invasive salmonellae infection in neonatal chickens observed in our laboratory during warmer months in Texas.     

Complement levels in dogs with familial canine dermatomyositis

CH50, C4, C2, and C3 levels were evaluated in 7 dogs affected with dermatomyositis and in 22 control dogs. Dogs with dermatomyositis did not have clinical evidence of active disease at the time of serum collection for complement assays. No absolute complement component deficiency was identified in dermatomyositis-affected dogs in this study; however, a statistical difference in C2 was identified between control dogs of non-collie breeds and control collies, suggesting there may be a breed difference in complement levels.     

Use of electrocardiographic analysis for investigation of ascites syndrome in broiler chickens.

This study was conducted (at high altitude [1969 meters]) to determine whether chicks predisposed to cardiac failure and ascites could be identified and followed during growout with non-invasive electrocardiographic (ECG) techniques. ECG recordings were made on 40 chicks at 1 week of age. All recordings were analyzed by quantifying the amplitude in millivolts of the R-, S-, and T-waves in each of the recordings. During the study, ascites-related mortality was 40%, with the majority of the deaths occurring between 5 and 8 weeks of age. Chicks exhibiting moderate-to-severe right ventricular hypertrophy, as identified by ECG analysis at 1 week of age, were predisposed to development of ascites. Thus, the variability in ascites-related mortality observed in field cases may be directly related to the number of predisposed chicks at the time of placement in the broiler house.     

Indigofera spicata (creeping indigo) poisoning of three ponies

Three ponies continuously grazed a pasture containing an estimated 24% Indigofera spicata (wet weight basis) for 4–6 weeks in April and May 2004. They developed ataxia, paresis, depression, muscle fasciculations, dysphagia, ptyalism and halitosis. Two also developed corneal opacity. One pony recovered with supportive treatment, but the other two were euthanased and necropsied. Neuropathology was not present in either case, but both livers had periacinar and periportal lymphocytic infiltrations and hydropic degeneration of mid‐zonal hepatocytes, with mild to moderate periacinar necrosis also evident in one. The I. spicata contained 2.66 mg 3‐nitropropionic acid (3‐NPA)/g dry matter and 1.5 mg indospicine/g dry matter. Indospicine, but not 3‐NPA, was detected in serum from both of the euthanased ponies and indospicine was detected in heart, liver and muscle from the one pony in which this assay was performed. The clinical syndrome closely resembled ‘Birdsville horse disease’ caused by I. linnaei and was similar to that reported in horses poisoned by the closely related species I. hendecaphylla and to 3‐NPA poisoning of other animals, including humans. 3‐NPA is thought to cause this neurological syndrome. To our knowledge, this is the first authenticated report of I. spicata poisoning in grazing animals. We also report here the first published evidence that 3‐NPA and indospicine exist in naturalised I. spicata in Australia and of the formation of indospicine residues in tissues of animals grazing paddocks infested with I. spicata.     

Typing of Haemophilus paragallinarum strains by using enterobacterial repetitive intergenic consensus-based polymerase chain reaction

The enterobacterial repetitive intergenic consensus polymerase chain reaction (ERIC-PCR) technique was used for fingerprinting of reference strains and Mexican isolates of Haemophilus paragallinarum. A total of nine ERIC patterns were given by the nine serovar reference strains of this bacteria. Two Modesto (C-2) reference strains from different sources showed the same ERIC pattern. Seventeen ERIC patterns were obtained among 29 Mexican isolates included in the study, belonging to serovars prevalent in Mexico (A-1, A-2, B-1, and C-2). Obtained results indicate that the ERIC-PCR technique could be used as a molecular laboratory tool for subtyping of H. paragallinarum.     

Prevalence, lesions, and differential diagnosis of Ollulanus tricuspis infection in cats

Ollulanus tricuspis were found in the stomachs of 26 of 201 cats which were mainly from Washington and Idaho. Twenty-four of the cats were from research or commercial breeding colonies (catteries) and two were pets. Twenty-seven percent of colony cats were infected with O. tricuspis, whereas only 2% of the pet cats were infected. No consistent clinical signs were seen. Histologically there was a significant increase in fibrous connective tissue in the lamina propria and in the number of lymphoid follicles and globule leukocytes in the gastric mucosa of infected cats. Histologic examination revealed no parasites in 13 of the 26 infected cats. The 26 infected cats were identified by examination of stomach washings. An additional 21 cats had larvae of other nematodes in their stomachs. These nematode larvae need to be differentiated from O. tricuspis.     

Effect of a selected Lactobacillus spp.-based probiotic on Salmonella enterica serovar enteritidis-infected broiler chicks

The effect of a Lactobacillus spp.-based probiotic (FM-B11) on Salmonella enterica serovar Enteritidis (SE) recovery was evaluated in liquid (Expt. 1) and lyophilized (Expt. 2) forms in two separate experiments with two trials each. For each trial, 80 broiler chicks were randomly allocated into two treatments: control and probiotic culture. All chicks were challenged with SE (approximately 10(4) colony-forming units [cfu]) upon arrival at our laboratory. In both experiments, probiotic culture was administered in the drinking water for 3 consecutive days at a final concentration of approximately 10(6) cfu/ml, beginning 1 hr after SE challenge. Cecal tonsils were aseptically removed at 24 and 72 hr postchallenge, followed by enrichment and plating on xylose lactose deoxycholate (XLD) agar for the presence or absence of Salmonella-typical colonies. In Expt. 1, a significant reduction (P < 0.05) in SE-positive samples was observed in both trials at 24 and 72 hr postchallenge. Additionally, in Expt. 2, the lyophilized probiotic decreased (P < 0.05) SE recovery at both 24 and 72 hr postchallenge compared with the control group in trial 1. In trial 2, SE evaluation was performed only at 72 hr after challenge and fewer (P < 0.001) treated samples were positive for SE. Results showed that application of either liquid or lyophilized probiotic culture in the drinking water for 3 consecutive days can help to reduce SE recovery from young birds, although further research is needed to elucidate the mechanism of this response.