Eight Holstein cows, 4 inoculated intracisternally in 1 quarter of the mammary gland with Escherichia coli and 4 noninfected controls, were administered ceftiofur sodium (3 mg/kg of body weight, IV, q 12 hours) for 24 hours, beginning at 14 hours after inoculation of infected cows. All challenge-exposed cows became infected, with mean +/-SEM peak log10 bacterial concentration in milk of 5.03 +/-0.69 colony-forming units/ml. The infection resulted in systemic signs (mean peak rectal temperature, 41.5 +/- 0.3 C; anorexia; signs of depression) and local inflammation (mean peak albumin concentration in milk, 7.89 +/- 1.71 mg/ml). Ceftiofur was detectable in milk from all challenge-exposed cows, compared with only 1 of 4 noninfected cows, and the mean period after inoculation that ceftiofur was detectable in milk was longer (P < 0.05) in infected (147.7 +/- 27.5 hours) than noninfected cows (1.3 +/- 1.3 hours). However, maximal ceftiofur concentration attained in milk for all cows was 0.28 micrograms/ml, and was 0.20 micrograms/ml or less for all but 2 milk samples collected for 10 days after challenge exposure. Mean serum concentration of ceftiofur peaked at 1.0 +/- 0.3 micrograms/ml and 0.7 +/- 0.1 micrograms/ml for infected and noninfected COWS, respectively. After each ceftiofur dose, mean peak and trough concentrations of ceftiofur in serum did not differ between groups; however, concentration of ceftiofur in serum was higher at 7 hours after each dose in noninfected cows, suggesting more rapid clearance of the drug in infected cows. Ceftiofur was not detected in serum (< 0.05 micrograms/ml) of any cow at or after 120 hours following inoculation of infected cows Storage of serum samples at -20 C for 3 weeks resulted in a 98.8% decrease in ceftiofur activity, compared with that in fresh serum samples. Eighty-seven percent of this loss occurred 30 minutes after mixing serum and ceftiofur; thus, about 13% of the original activity was lost in storage.

Polymyxin B and an antiserum against an Re mutant Salmonella typhimurium were evaluated for protective effect in an equine model of endotoxemia. Six 3- to 5-month-old foals were given endotoxin (0.25 micrograms/kg of body weight) IV after no pretreatment, or pretreatment with polymyxin B (6,000 U/kg, IV) or S typhimurium antiserum (1.5 ml/kg, IV). When given without pretreatment, endotoxin caused transient recumbency and increases in rectal temperature, and heart and respiratory rates. In addition, leukopenia and increases in circulating tumor necrosis factor (TNF) and interleukin 6 (IL-6) activities were detected. Compared with results obtained when endotoxin was given alone, pretreatment with polymyxin B resulted in significantly (P < 0.05) lower maximal plasma TNF and IL-6 activities, and significantly lower rectal temperature and respiratory rate. In contrast, compared with effects of endotoxin given without pretreatment, use of antiserum was associated with significantly (P < 0.05) higher respiratory rate, maximal plasma IL-6 activity, and total TNF response (as determined by areas under curves of plasma TNF vs time). These results indicate that polymyxin B may have potential as a treatment for equine endotoxemia. Salmonella typhimurium antiserum had no positive effect in this model, and, under certain conditions, may exacerbate the actions of endotoxin.

The metabolic responses of equine articular cartilage to incubation with bacterial lipopolysaccharide (LPS) were studied, using explant cultures of articular cartilage obtained from the metatarsophalangeal joints of 15 horses, age of which ranged from 3 months to 20 years. For comparison, explants were also established from the metatarsophalangeal joints of 3 calves. Explants were cultured for 3 days in medium containing various concentrations of LPS from 0 (control) to 100 microgram/ml. Glycosaminoglycan (GAG) released during the 3-day incubation was determined by a spectrophotometric assay, using the dye 1,9-dimethylmethylene blue. Newly synthesized GAG content was assayed by measuring [35S]sulfate incorporation during a 3-hour pulse labeling period. In addition, prostaglandin E2 (PGE2) synthesis was quantified, using a [3H]PGE2 radioimmunoassay kit and magnetic separation. Finally, explants from 3 animals were used to evaluate the effect of supplementing culture medium with 5% serum on the response of explants to LPS, and explants from 1 horse were used to compare responses to stimulation with LPS derived from 2 bacterial sources. Equine explants cultured with bacterial LPS had a dose-dependent decrease in synthesis and increase in release of GAG, and these responses were significantly (P < 0.0001) greater in explants from younger horses. In addition, equine explants had a significant (P = 0.0001) dose-dependent increase in concentration of PGE2 released into the culture medium in response to incubation with LPS. Comparison of data for GAG synthesis from equine and bovine explants revealed a significant (P = 0.025) difference in responsiveness to LPS between the 2 species. Equine explants tended to have a greater suppression of GAG synthesis in response to incubation with increasing concentrations of LPS than did age-corrected bovine samples.

Water quality is critical for poultry farming. This study assessed the physical, chemical and microbiological quality of drinking water in small-layer farms in Southern Mozambique and identified potential risk factors for total coliform (TC) and Escherichia coli contamination of drinking water. In 20 farms, 57 samples were collected and examined for pH, nitrate content (NC), nitrite level (NL) and total hardness contents (TH). Furthermore, TC and E. coli growth were assessed at 37 °C. One hundred per cent of the drinking water was of acceptable quality in terms of pH (6.5-8.5), NC (50 mg/L) and NL (3 mg/L). Total hardness contents exceeded the recommended standard in 37.5% of borehole water samples and 91.7% of tap water samples, respectively. Total coliform and E. coli were found in 40% and 15% of water samples. Tap water samples had the greatest contamination, with TC and E. coli levels of 41.7% and 16.7%, respectively. Although not statistically significant, sampling from the beginning of the nipple line (p = 0.101, OR = 7.357, 95% confidence interval &#91;CI&#93;: 0.678-79.886) and not cleaning the rearing equipment regularly (p = 0.098, OR = 3.966, 95% CI: 0.766-20.280) were factors affecting the TC growth. Sampling from the tank water source (p = 0.001, OR = 0.005, 95% CI: 0.000-0.121) and borehole water source (OR = 13 585) and not cleaning the equipment consistently (p = 0.073, OR = 9.682, 95% CI: 0.810-115.68) were all factors affecting E. coli growth. It is concluded that the TH and microbiological quality of the drinking water of the study region are inadequate. Regular water quality assessments should be incorporated into Mozambican layer farm management to limit the potential for health concerns, and farmers should thoroughly clean and disinfect their rearing equipment. CONTRIBUTION: We should incorporate regular water quality assessments into Mozambican layer farm management to limit the potential for health concerns, and farmers should thoroughly clean and disinfect their rearing equipment

Escherichia coli is present in the normal intestinal flora but some strains can cause intestinal and extraintestinal diseases, and research on its presence in food of animal origin is in the interests of public health. This study was designed to characterise E. coli strains according to their origin, their carriage of virulence genes specific for certain pathogroups, and phylogenetic group affiliation.

Introduction: Avian pathogenic Escherichia coli (APEC) is a leading cause of extraintestinal infection and heavy economic losses. Imparting immunity after vaccination with live attenuated strain vaccination is an ideal strategy for infection control. This study considers an FtsK knockout mutant strain as a candidate. Material and Methods: An FtsK knockout mutant of APEC strain E058 was constructed and the pathogenicity of the mutant and wild-type strains was further evaluated in chickens. Results: The 50% lethal doses of each strain for one-day-old specific-pathogen-free (SPF) chickens challenged experimentally via trachea were 105.5 and 107.0 colony-forming units (CFU) respectively. Chickens challenged with the wild-type strain exhibited typical signs and lesions of avian colibacillosis, while those inoculated with the mutant strain showed mild pericarditis and pulmonary congestion. The growth rate of the FtsK mutant strain was much slower than the wild-type strain in the heart, spleen, liver, and lung of infected chickens. Conclusion: These results indicated that the APEC FtsK mutant can be attenuated for chickens, and that this mutant has the potential for the development of an APEC vaccine.

Escherichia coli is a widespread environmental pathogen frequently causing dairy cow mastitis. This bacterium is particularly capable of acquiring antimicrobial resistance, which can have severe impacts on animal food safety and human health. The objective of the study was to investigate antimicrobial resistance and genetic correlations of E. coli from dairy cow mastitis cases in northern China.

A conclusive study was conducted for preparation and evaluation of combinedinactivated entero-4 vaccine containing bovine rotavirus (BRV), bovine coronavirus(BCV), E. coli K99 and toxoid of C. perfringens type "C". Laboratory and field evaluations were conducted on laboratory animals, calves and late pregnant cows with monitoring the active and passive antibodies in vaccinated cows and their offspring respectively. Laboratory evaluation proved purity, safety and high efficacy of the vaccine without interference between different vaccine ingredients. Field evaluation gave satisfactory results when pregnant cows vaccinated at late stage of pregnancy with high neutralizing antibody titers against BRV, BCV and C. perfringens as well as high E. coli agglutinating titers. Maternal immunity passively protected offspring during the critical period of age and remained protected till the end of sampling time (30th day post parturition).

Anualmente o tráfico de animais silvestres retira milhões de aves da natureza. Os cardeais (Paroaria coronata) e cardeais-do-nordeste (Paroaria dominicana) estão incluídos entre as espécies de aves mais traficadas. A microbiota cloacal de passeriformes de vida livre é composta principalmente por bacilos e cocos gram-positivos, já os bacilos gram-negativos predominam em aves de cativeiro. Em situações de estresse e baixa de imunidade as bactérias gram-negativas podem causar infecções oportunistas. O presente trabalho identificou bactérias da microbiota da cloaca de 49 espécimes de P. coronata e P. dominicana apreendidas do tráfico de animais silvestres em São Paulo (SP). Foram isoladas treze espécies de bactérias gram-negativas, incluindo Salmonella spp. e Pseudomonas aeruginosa. A maior frequência de ocorrência foi de Escherichia coli, identificada em 42/49 (85,7%) das amostras fecais. Dentre os isolados de E. coli, 21/42 pertenciam aos grupos filogenéticos B2 e D, relacionados a estirpes patogênicas que causam doença extraintestinal em humanos. Klebsiella pneumoniae foi isolada em 28/49 (57,1%) das amostras. Esses resultados reforçam que as condições estressantes a que esses animais são submetidos em situações de tráfico, incluindo o contato com humanos, podem favorecer a colonização da microbiota cloacal das aves por patógenos, o que representa um risco para a sua reintrodução na natureza considerando-se o possível contato com humanos e outros animais.