Short communication: Iodine concentrations in serum, milk, and tears after feeding Ascophyllum nodosum to dairy cows-A pilot study

Kelp (Ascophyllum nodosum) is rich in iodine and often fed by organic dairy producers as a mineral supplement to support animal health. A commonly held belief is that kelp supplementation decreases susceptibility to infectious bovine keratoconjunctivitis due to increased iodine concentrations in tears. Whereas serum and milk iodine concentrations are positively correlated and modulated by oral iodine supplementation, nothing is known about the iodine concentration of tears. Therefore, the 3 objectives of this pilot study were to determine (1) the iodine content of tears, milk, and serum of cows after being fed kelp for 30d; (2) the trace mineral and thyroid status of cows before (d 0) and after being fed kelp for 30d; and (3) the in vitro growth rate of bacteria in tears (Moraxella bovis) or milk (Staphylococcus aureus, Escherichia coli, Streptococcus uberis) collected from cows fed no kelp (d 0) or kelp (d 30). Cows (n=3/treatment) were individually fed 56g of kelp per day (n=3/treatment) or not (n=3/no treatment) for 30 d. Daily feed intake of the TMR was recorded and weekly TMR, kelp, milk, blood and tear samples were collected and analyzed for iodine. The feed samples were pooled and further analyzed for other minerals. On d 0 and 30, liver biopsies and blood samples were collected and analyzed for mineral content and thyroid hormone concentrations, respectively. An inhibition test used milk and tear-soaked plates from kelp-fed cows (d 0 and 30) as well as 1 and 7.5% iodine as positive and distilled water as negative control. As expected, serum iodine concentrations were positively correlated with milk and tear iodine concentrations. Whereas the iodine concentrations in serum increased significantly in the kelp-fed cows during the 30-d study, milk and tear iodine concentrations increased only numerically in these cows compared with the control group. Liver mineral profiles were comparable between groups and generally did not change over the course of the study. Thyroid hormones remained overall within the reference range throughout the trial. Neither milk nor tears from kelp-fed cows inhibited in vitro growth of any of the plated bacteria. In summary, serum iodine concentration was correlated with the iodine concentration in milk and tears and feeding kelp increased only the serum iodine levels of cows in this trial. Bacterial growth was not inhibited in milk and tears of kelp-fed cattle in vitro, and prevention of infectious bovine keratoconjunctivitis would not be based solely on increased iodine concentrations in tears.

Phylogenetic analysis and genetic diversity of 3' region of rtxA gene from geographically diverse strains of Moraxella bovis, Moraxella bovoculi and Moraxella ovis

The cytotoxin A (MbxA) is one of the main virulence factors of Moraxella bovis involved in the pathogenesis of infectious bovine keratoconjunctivitis (IBK). Moraxella ovis and Moraxella bovoculi, suspected to be associated with infectious keratitis in sheep and cattle respectively, also have a gene that encodes the cytotoxin A (movA and mbvA, respectively). The aim of this study was to determine the molecular sequence of the 3' region of the cytotoxin gene of Moraxella spp. strains isolated from clinical cases to establish phylogenetic and evolutionary comparisons. PCR amplification, nucleotide sequencing (nt) and amino acid (aa) sequence prediction were performed, followed by the sequences comparison, identity level calculation and selective pressure analysis. The phylogenetic reconstruction based on nt and aa sequences clearly differentiate M. bovis (n=15), M. bovoculi (n=11) and M. ovis (n=7) and their respective reference strains. An alignment of 843nt revealed high similarity within bacterial species (MbxA=99.9% nt and aa; MbvA=99.3% nt and 98.8% aa; MovA=99.5% nt and 99.3% aa). The similarity of partial sequences (nt 1807-2649) of MbxA in relation to MbvA and MovA ranged from 76.3 to 78.5%; similarity between MbvA and MovA ranged from 95.7 to 97.5%. A negative selection on mbvA and movA sequences was revealed by the molecular evolution analysis. The phylogenetic analysis of movA and mbvA allowed different strains of Moraxella spp. to be grouped according to the period of isolation. Sequence analysis of cytotoxin may provide insights into genetic and evolutionary relationships and into the genetic/molecular basis of Moraxella spp.

Molecular and phenotypic analysis of Moraxella spp. associated with infectious bovine keratoconjunctivitis in Uruguay

Infectious bovine keratoconjunctivitis (IBK) is a common ocular disease of cattle, which is generally thought to be caused by Moraxella bovis. However, a recently characterized Moraxella, M. bovoculi, has been isolated from animals with IBK. The aim of this study was to identify and characterize strains of Moraxella spp. obtained from IBK cases in different geographic locations within Uruguay. Ribosomal gene sequencing indicated that there were two groups of isolates that showed homology with either M. bovis or M. bovoculi. Phylogenetic analysis confirmed the presence of two species as the isolates grouped in different branches of the dendrogram. Conventional biochemical characterization did not distinguish between the species; only 9/25 isolates which had genetic homology with M. bovoculi showed any differences in biochemistry.

Ulcerative blepharitis and conjunctivitis in adult dairy cows and association with Moraxella bovoculi

Nine lactating dairy cows were evaluated because of eye lesions. Examination revealed mild to severe ulceration of the lower and/or upper eyelids, mild to severe swelling surrounding affected eyes, and profuse lacrimation. Lesions typically affected 1 eye, and involved the eyelid skin and conjunctiva. Oxytetracycline treatment led to cure within 2 wk.

Infectious bovine keratoconjunctivitis antimicrobial therapy

Infectious bovine keratoconjunctivitis (IBK) is one of the most common diseases of cattle and is of major economic importance. If the primary aetiological agent, Moraxella bovis, is successfully eliminated from ocular tissues corneal ulcers heal at a constant rate. If treatment is unsuccessful ulcer reoccurrence may follow initial healing. Appropriate antimicrobial selection requires knowledge of antimicrobial sensitivities and distribution in ocular tissues and tears. Drugs may be delivered to the eye in several ways: subconjunctival injection, topical application and systemic administration. While therapeutic efficacy is affected by the frequency and mode of drug delivery, variations between intensive and extensive enterprises dictate the practical method of antimicrobial delivery. Specific recommendations for antimicrobial therapies targeting Australian IBK outbreaks are dependent upon antimicrobial pharmacokinetics, drug regulations and associated costs.

[Infectious bovine keratoconjunctivitis (IBK) in cows, clinical and lab review at four farms]

After several reports to the GD (Dutch Animal Health Service) from practitioners in The Netherlands concerning serious Infectious Bovine Keratoconjunctivitis (IBK) in dairy herds during summer and autumn 2003, the GD has carried out a pilot-study to determine the most responsible agent. This pilot was thought to be important because of the painfulness of the illness and problems like, (for the farmer) an intensive and difficult therapy. Also the report of a Chlamydophilae infection causing IBK in a dairy herd in the UK prompted to this study. The most frequently isolated infectious agent in our study was Moraxella, probably M. bovis. For the presence of Chlamydophila, mycoplasmata or BHV1 viruses were no indications.

Molecular diversity of Moraxella bovis isolated from Brazil, Argentina and Uruguay over a period of three decades

The molecular profile of 30 Moraxella bovis strains, recovered from outbreaks of infectious bovine keratoconjunctivitis in Argentina, Brazil and Uruguay between 1974 and 2001, was determined through randomly applied polymorphic DNA (RAPD) analysis. Molecular profiles of nine strains recovered after 1990 varied from those recovered before 1990. The profiles of 13 strains (48%) differed from those of three vaccinal strains extensively used since 1984 in Argentina and Uruguay. Eight Argentinean strains, one from Brazil and two from Uruguay had identical RAPD profiles. Strains belonging to different serogroups had identical RAPD profiles, demonstrating that this technique was not able to discriminate among strains with low cross-reactivity indices. RAPD may be helpful in the primary characterization of M. bovis strains, but it does not replace serological characterization.

An RTX operon in hemolytic Moraxella bovis is absent from nonhemolytic strains

Pathogenic isolates of Moraxella bovis express a calcium-dependent transmembrane pore forming cytotoxin that is an RTX toxin encoded by mbxA. The DNA flanking mbxA was cloned and sequenced to determine if M. bovis contained a classical RTX operon. Open reading frames (ORFs) with deduced amino acid sequence homology to putative activation (RTX C) and transport (RTX B and D) proteins were identified and have been designated MbxC, MbxB, and MbxD, respectively. Thus, hemolytic M. bovis contains a typical RTX operon comprised of four genes arranged (5'-3') mbxCABD. In addition, the deduced amino acid sequences of DNA flanking mbxCABD revealed ORFs with amino acid sequence similarity to transposases (5'). At the 3' end of the mbx gene cluster, an ORF with homology to bacterial tolC genes was identified. Thus, as with the cya RTX operon of Bordetella pertussis, M. bovis appears to have a secretion accessory protein linked to RTX genes. Analysis of genomic DNA isolated from 5 nonhemolytic M. bovis strains by PCR and Southern blotting revealed the absence of mbxCABD. These strains did, however, amplify with primers specific for the 5' region flanking mbxC. M. bovis harbors a classical RTX operon that is absent in nonhemolytic strains.

Infectious bovine keratoconjunctivitis and lymphofollicular hyperplasia of the third eyelid in heifers

On a dairy cattle farm, infectious bovine keratoconjunctivitis was diagnosed in 29 (24%) calves and heifers aged from 2 weeks to 1 year old. The highest infection rate (18%) occurred in animals aged 3-6 months. The bacteriological examination of swabs from the affected animals yielded several species of bacteria: Moraxella bovis, Neisseria ovis, N. cuniculi, plasma coagulase-negative Staphylococcus spp., alpha-haemolytic Streptococcus spp., Arcanobacterium pyogenes and Escherichia coli. Moraxella bovis and N. ovis were the most common isolates. Hyperplasia of the lymphatic tissue of the third eyelid in the form of nodules 7-8 mm in diameter was diagnosed in two heifers aged 8 and 10 months.

Report of a case of bronchopneumonia associated with Moraxella bovis isolation in a chamois (Rupicapra pyrenaica)

A case of fibrinopurulent bronchopneumonia associated with Moraxella bovis infection in a chamois (Rupicapra pyrenaica) is described. The animal, a 4-month-old female, was referred by the staff warden of the National Game Reserve of Freser-Setcases (Catalonia, north-eastern Spain). The animal was in good general condition and was found 4 h before death. On necropsy the lungs were congested and oedematous, with haemorrhagic areas in the cranial and middle lobes. The microscopic lesions were those of a fibrinopurulent bronchopneumonia. Microbiological study of the samples obtained showed numerous small beta-haemolytic colonies in pure culture, identified as Moraxella (Moraxella) bovis.

Analyses of lipopolysaccharides, outer membrane proteins and DNA fingerprints reveal intraspecies diversity in Moraxella bovis isolated in Argentina

Intra-specific diversity within Moraxella bovis was investigated analysing DNA fingerprints, outer membrane proteins (OMP) and lipopolysaccharides (LPS) profiles. Three collection strains and 57 isolates of M. bovis, collected during 3 years from cattle with infectious bovine keratoconjunctivitis (IBK) symptoms, from diverse geographical locations of Argentina, were examined. The LPS and OMP profiles were studied through SDS-PAGE analysis and genotype was determined by PCR-DNA fingerprinting. Genotyping identified five DNA types while analysis of LPS and OMP profiles identified three rough LPS types and three OMP types among the 60 isolates of M. bovis including the three collection strains. None of the three methods employed to assess diversity was discriminating when used alone because the degree of heterogeneity in each group of surface structures was limited, but when data of each typing method were combined, 15 distinct subgroups were determined. This subgrouping was clearly able to differentiate isolates of the same genotype. These typing methods appear to be useful to assess different aspects of the disease such as the diversity within a population of M. bovis associated to epidemic conditions, track the causal agent in an outbreak of the disease, monitoring vaccination programs and studies on virulence.

Antimicrobial susceptibility of Moraxella bovis

The antimicrobial susceptibility of 55 isolates of Moraxella bovis to seven antibiotics was evaluated by broth microdilution procedures. The isolates had an MIC90 of < or = 1 mg/l to erythromycin, ceftiofur, and ampicillin; 4 mg/l to tilmicosin; 16 mg/l to tylosin and gentamicin; and had MIC90s of > or = 32 mg/l for oxytetracycline. The modal MIC values for these antibiotics were as follows: ampicillin, < 0.25 mg/l; ceftiofur, < or = 0.125 mg/l; tilmicosin, 2 mg/l; tylosin, 8 mg/l; erythromycin 1 mg/l; oxytetracycline, < or = 0.5 mg/l; and gentamicin, < or = 0.5 mg/l. This in vitro data showed most antibiotics have low MICs that are suggestive of clinical efficacy.

Combined parenteral and oral administration of oxytetracycline for control of infectious bovine keratoconjunctivitis

OBJECTIVE

To determine whether combined parenteral and oral administration of oxytetracycline would ameliorate a herd outbreak of infectious bovine keratoconjunctivitis (IBK) and to compare efficacy of this regimen with that of subconjunctival administration of procaine penicillin G.

DESIGN

Randomized field trial.

ANIMALS

119 Hereford calves in a herd undergoing a naturally occurring outbreak of IBK.

PROCEDURE

Calves were randomly assigned to 1 of the following 3 groups: oxytetracycline treatment, procaine penicillin G treatment, and control. After initial treatment, calves were examined 3 times/wk for 7 weeks. The surface area of all corneal ulcers was measured during each examination. Ocular secretions were collected from all calves at least weekly and were tested for Moraxella bovis.

RESULTS

Calves treated with oxytetracycline had a lower prevalence of IBK than did calves treated with procaine penicillin G or control calves and required fewer additional treatments than did calves treated with procaine penicillin G. Mean time for healing of corneal ulcers was significantly less for calves that received oxytetracycline or procaine penicillin G than for control calves. Calves treated with oxytetracycline developed fewer corneal ulcers and fewer recurrent ulcers than did calves in the other groups. Moraxella bovis was isolated less often from ocular secretions collected from calves in the oxytetracycline group than from calves in the other groups.

CLINICAL IMPLICATIONS

Combined parenteral and oral administration of oxytetracycline appears to be an effective method of reducing severity of a herd outbreak of IBK and may be superior to treatment of affected animals with procaine penicillin G.

Shunt nephritis associated with Moraxella bovis

Moraxella bovis was repeatedly isolated from cerebrospinal fluid in a girl with two episodes of shunt nephritis. Clinical remission of nephritis was achieved only after shunt replacement. A list of about 20 infectious agents reported to date in patients with shunt nephritis is given. M. bovis is yet another agent previously not reported in patients with shunt nephritis.

Identification of Moraxella bovis and related species from calves with IBK and goats by qualitative genetic transformation assay

Eight Moraxella bovis strains isolated from bovine pink eye, 16 Moraxella bovis related strains isolated from healthy goats nasal flora, one nonhemolytic Moraxella sp. isolated from bovine conjunctivitis and different collection strains of Moraxella and Branhamella genus were studied through the combined use of qualitative genetic transformation assay and the ability to grow on a moraxella bovis defined medium (medium MB). Crude DNA extracted from the strains studied were used to transform two mutant auxotroph competent strains of Moraxella bovis CIP 103741 and CIP 103743. Non-specific positive transformation was obtained with mutant assay strain CIP 103743 when treated with DNA from caprine or bovine Moraxella strains, collection strains of Moraxella bovis, Moraxella lacunata, Moraxella nonliquefaciens and strains of Branhamella genus, whereas specific transformation was observed with mutant assay CIP 103741 when treated only with DNA from all the Moraxella bovis (collection and clinical isolates) and 14 of the 16 caprine Moraxella bovis related strains. The specificity and the simplicity of the test make it suitable for use in clinical laboratories.

Prolonged occurrence of Moraxella bovis infection on a restricted heifer farm

An epizootiologic study was conducted for infectious bovine keratoconjunctivitis (IBK) on a large grassland farm rearing a total of 1,300-1,400 heifers during May to October in both 1991 and 1992. Heifers were examined for infection with Moraxella bovis, and isolation of M. bovis from the affected eyes and from Asian face flies (Musca bezzii Patton et Cragg) swarming on the heifer face was carried out. During the observation period, 10.7% of the heifers in 1991 and 5.3% of the heifers in 1992 were affected with IBK. Eight M. bovis isolates were isolated from the ocular swabs of affected heifers with IBK for 2 years and identified by biochemical examinations and Southern DNA-DNA hybridization, but no M. bovis was obtained from 331 Asian face flies tested. Plasmid profile analysis showed that two plasmids (35-kb and 4.0-kb) were commonly found in all 8 M. bovis isolates. This indicates that M. bovis isolates with the same plasmid profile were widely disseminated on this farm for 2 years.

An investigation of colonization of the conjunctival sac of sheep by bacteria and mycoplasmas

The conjunctival sacs of 100 healthy adult ewes and 20 lambs and 76 adult ewes affected by ovine keratoconjunctivitis (OKC) were examined microbiologically. Branhamella ovis was the only organism regularly isolated from healthy ewes and lambs, Mycoplasma conjunctivae was isolated from the conjunctival sac of nine ewes but its occurrence was not associated with clinical signs of ovine keratoconjunctivitis. Mycoplasma conjunctivae and Branhamella ovis were isolated significantly more often from eyes affected by OKC than from unaffected eyes.

[An outbreak of keratoconjunctivitis in a dairy farm]

An outbreak of infectious kerato-conjunctivitis is described in a dairy herd during the (winter)stable period. Moraxella was isolated from lacrimation fluid from three animals. The development of the infection was possibly precipitated by a vaccination with modified live IBR virus, adenovirus type 3 and parainfluenza virus type 3. Presumably, climatological-stable conditions play an important role in the clinical manifestation of the infection.