Beta-defensins are antimicrobial peptides produced by several cell types, including respiratory epithelia and leukocytes. Expression of some beta-defensins is increased by bacterial-induced inflammatory responses whereas expression of other beta-defensins is constitutive. Two beta-defensins are expressed in lungs of sheep (sheep beta-defensin-1 and -2; SBD-1/-2) and expression of SBD-1 is incre...

The ruminant-specific leukotoxin (Lkt) of Mannheimia haemolytica is the key virulence factor contributing to the pathogenesis of lung injury in bovine pneumonic pasteurellosis. Previous studies by us and others indicate that M. haemolytica Lkt binds to CD18, the beta subunit of bovine beta(2)-integrins on leukocytes, and that the species specificity of Lkt-induced effects is resident in the bet...

OBJECTIVE To characterise eight isolates of a Gram-negative organism obtained from the upper respiratory tract of cattle showing evidence of mild upper respiratory tract disease. DESIGN The isolates were compared with the five recognised species within the genus Mannheimia - M haemolytica, M glucosida, M granulomatis, M ruminalis and M varigena--using a range of phenotypic and genotypic metho...

BACKGROUND Bacterial pneumonia in goats is usually caused by Mannheimia haemolytica and Pasteurella multocida. Another important infection disease in lactating goats is intramammary infection producing mastitis, usually associated with coagulase-negative Staphylococcus spp. However, treatment of bacterial pneumonia in goats not affected by mastitis problems should be restricted to antimicrobial...

Mannheimia haemolytica leukotoxin is produced during the logarithmic growth phase in submerged culture in RPMI 1640 medium with and without the addition of foetal calf serum or albumin. In order to establish a pattern of optimal leukotoxin production in small volumes in submerged cultures and to define some parameters involved, two high leukotoxin producing Mannheimia haemolytica strains were g...

in this study, we performed a bacteriological investigation on bovine respiratory infections. additionally, the study evaluates the efficacy of florfenicol 30 µg produced by rooyan darou company (test group) as compared to a similar drug produced by aboraihan company (control group). sampling was carried out on 30 calves at two farms with 30-55% incidence rate of respiratory disorders. nasophar...

Clinafloxacin is a broad-spectrum fluoroquinolone that was originally developed and subsequently abandoned in the late 1990s as a human health antibiotic for respiratory diseases. The purpose of this study was to investigate the activity of clinafloxacin as a possible treatment for respiratory disease in cattle and pigs. Minimum inhibitory concentration (MIC) values were determined using Clinic...

The efficacy of an early and low inoculum-adjusted marbofloxacin treatment was evaluated on microbiological and clinical outcomes in calves infected with 4.10(7) CFU of Mannheimia haemolytica A1. Twenty-two calves were included based on their rectal temperature rise in the 10 h after challenge and allocated in four groups, receiving a single intramuscular injection of saline (CON), 2 mg/kg marb...

White-tailed deer (Odocoileus virginianus) are reservoirs for Mycobacterium bovis in northeast Michigan, USA. Production of nitric oxide (NO) by activated macrophages is a potent mechanism of mycobacterial killing. The capacity of macrophages to produce NO, however, varies among mammalian species. The objective of this study was to determine if mononuclear cells from white-tailed deer produce n...

Sir, Bovine respiratory disease (BRD) is one of the economically most important diseases in animal production, with global losses of the feedlot industry due to BRD being estimated to be over US$ 3 billion per year. Antimicrobial agents, particularly macrolides, are commonly used to combat bacteria involved in BRD, such as Mannheimia haemolytica, Pasteurella multocida and Histophilus somni. Aft...