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.

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.

A multiplex real-time PCR assay for the detection and differentiation of five bovine pinkeye pathogens.

Infectious bovine keratoconjunctivitis (IBK), also known as pinkeye, is one of the most common eye diseases in cattle. Several pathogens have been associated with IBK cases, however, Moraxella bovis, Moraxella bovoculi, Mycoplasma bovis, Mycoplasma bovoculi and bovine herpesvirus type 1 (BHV-1) are most frequently observed. A multiplex real-time PCR assay using two reactions was developed for the detection and differentiation of these five pathogens. Detection sensitivities of the multiplex assays were compared to singleplex reactions testing for the same targets. Correlation coefficients (R2) of >0.99, and PCR efficiencies between 92 and 106% were demonstrated in all singleplex and multiplex real-time PCR reactions. The limits of detection (LOD) of multiplex assays for Moraxella bovis, Moraxella bovoculi, Mycoplasma bovis, Mycoplasma bovoculi and BHV-1 were 19, 23, 25, 24 and 26 copies per reaction, respectively. No cross amplification was observed for specificity testing of 179 IBK positive clinical samples and 55 non-target clinical samples. Percentage of clinical samples positive for Mycoplasma bovoculi, Moraxella bovoculi, Moraxella bovis, BHV-1 and Mycoplasma bovis were 88.8% (159/179), 75.9% (136/179), 60.3% (108/179), 11.7% (21/179) and 10.0% (18/179), respectively. Moraxella bovis, Moraxella bovoculi and Mycoplasma bovoculi were more prevalent than Mycoplasma bovis and BHV-1 in IBK samples collected from animals in this study population. Our data indicates that the multiplex real-time PCR panel assay is highly sensitive and highly specific for the detection and differentiation of the five major pathogens associated with bovine pinkeye.

Serologic cross-reactivity of Australian Moraxella bovis to vaccinal bacterin strains as determined by competitive ELISA.

OBJECTIVE: To conduct a serologic survey and define pili antigenic variability via the serologic cross-reactivity of Moraxella bovis isolates from naturally occurring infectious bovine keratoconjunctivitis (IBK) outbreaks in Australia. This project applies to the development of an M bovis pili-based vaccine targeting Australian strains originating from intensive cattle producing regions. PROCEDURE: Ocular swabs were collected from cattle affected with clinical signs of IBK from 25 veterinary practices. Standard criteria were used to identify 70 M bovis. Pure, piliated isolates were evaluated with a modified competitive enzyme-linked immunosorbent assay (ELISA) for cell-bound M bovis pili to determine their serologic cross-reactivity with pili of vaccinal bacterin strains EPP63, FLA64, and SAH 38. RESULTS: Sixty-four percent (45/70) of M bovis isolates demonstrated homologous pili antigens to a vaccinal strain. M bovis isolates homologous to one of the three vaccinal strains were obtained in 77% (34/44) of IBK outbreaks sampled. No IBK outbreak had isolates homologous to more than one vaccinal strain; however, 29% (10/34) of outbreaks with a cross-reacting strain had non-cross-reacting strains as well. CONCLUSION: The similar prevalence of pilus antigen homology to strain FLA64 was observed with isolates derived from NSW, Tasmania, and Victoria, compared with results of prior smaller serologic studies, suggests that the common pilus antigens in M bovis within Australia have been relatively stable over the last 20 years. The prevalence of a limited number of pilus antigens in M bovis suggest that the application of a vaccine containing the bacterial strains EPP63, FLA64, and SAH38 may provide a useful management tool for reducing production losses associated with IBK in Australia.

Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry identification of Moraxella bovoculi and Moraxella bovis isolates from cattle.

Infectious bovine keratoconjunctivitis (IBK) is an economically significant disease caused by Moraxella bovis. Moraxella bovoculi, although not reported to cause IBK, has been isolated from the eyes of cattle diagnosed with IBK. Identification of M. bovis and M. bovoculi can be performed using biochemical or DNA-based approaches, both of which may be time consuming and inconsistent between laboratories. We conducted a comparative evaluation of M. bovoculi and M. bovis identification using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) with a database provided by Bruker Daltonics (termed the BDAL database), the BDAL database supplemented with spectra generated in our study (termed the UNLVDC database), and with PCR-restriction-fragment length polymorphism (PCR-RFLP) typing. M. bovoculi ( n = 250) and M. bovis ( n = 18) isolates from cattle with or without IBK were used. MALDI-TOF MS using the UNLVDC database correctly identified 250 of 250 (100%) of M. bovoculi and 17 of 18 (94%) of M. bovis isolates. With the BDAL database, MALDI-TOF MS correctly identified 249 of 250 (99%) of M. bovoculi and 7 of 18 (39%) of M. bovis isolates. In comparison, the PCR-RFLP test correctly identified 210 of 250 (84%) of M. bovoculi and 12 of 18 (66%) of M. bovis isolates. Thus, MALDI-TOF MS with the UNLVDC database was the most effective identification methodology for M. bovis and M. bovoculi isolates from cattle.

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.

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.

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.

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.

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.

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.

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.

[An outbreak of keratoconjunctivitis in a dairy farm]. / Een uitbraak van kerato-conjuctivitis op een melkveebedrijf.

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.

[Infectious bovine keratoconjunctivitis (IBK) in cows, clinical and lab review at four farms]. / Infectieuze keratoconjunctivitis bij runderen, overzicht aan de hand van kliniek- en laboratoriumonderzoek op vier bedrijven.

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.

Evaluation of biofilm-forming capacity of Moraxella bovis, the primary causative agent of infectious bovine keratoconjunctivitis.

The difficulties in preventing and treating infectious bovine keratoconjunctivitis (IBK) and the consequent impact on the cattle industry worldwide emphasize the need to better understand this infectious process along with the biology of Moraxella bovis, its primary causative agent. Although there is increasing evidence that bacterial biofilms participate in a variety of ocular infections by direct biofilm formation on the surfaces of the eye, IBK has not been considered as a biofilm-based disease so far, and even more, no information is currently available regarding the ability of M. bovis to adopt a biofilm lifestyle. In the present research, we demonstrated the capacity of M. bovis clinical isolates and reference strains to form biofilms on different abiotic surfaces and culture conditions, and provided qualitative and quantitative information on the biofilm growth and architecture of mature biofilms. In addition, our data indicated that the type IV pili play a critical role in the biofilm formation in vitro. Most significantly, we proved that through exposure to MgCl2 type IV pili are removed from the cell surface, not only preventing M. bovis biofilm formation but also disassembling preformed biofilms. These results could constitute a new approach in the understanding of M. bovis colonization process in cattle eye and/or nasal cavity, and may aid in the development of future antimicrobial strategies for the control of IBK.

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.

Descriptive epidemiology of Moraxella bovis, Moraxella bovoculi and Moraxella ovis in beef calves with naturally occurring infectious bovine keratoconjunctivitis (Pinkeye).

PROBLEM ADDRESSED: Infectious bovine keratoconjunctivitis (IBK) is an ocular disease that causes substantial weight loss in beef calves. OBJECTIVE: The objective of this study was to evaluate the association between Moraxella bovoculi, Moraxella bovis and Moraxella ovis and IBK incidence. METHODS AND APPROACH: A cohort design was used. From 239 calves and 478 eyes, 77 randomly chosen eyes were monitored for M. bovoculi, M. bovis, M. ovis and IBK incidence over 4 months. One hypothesis tested was that IBK hazard in eyes was not associated with detection of M. bovoculi, M. bovis and M. ovis. A secondary hypothesis tested that IBK cases were not associated with increased prevalence of M. bovoculi, M. bovis and M. ovis. RESULTS: 23% of 77 eyes developed IBK. M. ovis was identified in one IBK-negative eye. The adjusted hazard ratio (HR) for IBK incidence from eyes where M. bovoculi or M. bovis were recovered prior to disease occurrence were not statistically significant (M. bovoculi HR=1.38, 95% CI: 0.54-3.53, p=0.49, M. bovis HR=1.60, 95% CI: 0.48-5.53, p=0.44). The adjusted hazard ratio for M. bovoculi in IBK lesions was 6.45 (95% CI: 3.35-12.44, p<0.001). The adjusted hazard ratio for M. bovis in IBK lesions was 2.33 (95% CI: 1.22-4.45, p=0.01). CONCLUSION: A temporal association between prior exposure to M. bovoculi or M. bovis and subsequent IBK incidence was not demonstrated. However, M. bovoculi and M. bovis are more frequently recovered from eyes with IBK lesions than unaffected eyes and this provides weak evidence for a causal role.

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.

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.