Early canine plaque biofilms: characterization of key bacterial interactions involved in initial colonization of enamel

Periodontal disease (PD) is a significant problem in dogs affecting between 44% and 63.6% of the population. The main etiological agent for PD is plaque, a microbial biofilm that colonizes teeth and causes inflammation of the gingiva. Understanding how this biofilm initiates on the tooth surface is of central importance in developing interventions against PD. Although the stages of plaque development on human teeth have been well characterized little is known about how canine plaque develops. Recent studies of the canine oral microbiome have revealed distinct differences between the canine and human oral environments and the bacterial communities they support, particularly with respect to healthy plaque. These differences mean knowledge about the nature of plaque formation in humans may not be directly translatable to dogs. The aim of this study was to identify the bacterial species important in the early stages of canine plaque formation in vivo and then use isolates of these species in a laboratory biofilm model to develop an understanding of the sequential processes which take place during the initial colonization of enamel. Supra-gingival plaque samples were collected from 12 dogs at 24 and 48 hour time points following a full mouth descale and polish. Pyrosequencing of the 16S rDNA identified 134 operational taxonomic units after statistical analysis. The species with the highest relative abundance were Bergeyella zoohelcum, Neisseria shayeganii and a Moraxella species. Streptococcal species, which tend to dominate early human plaque biofilms, had very low relative abundance. In vitro testing of biofilm formation identified five primary colonizer species, three of which belonged to the genus Neisseria. Using these pioneer bacteria as a starting point, viable two and three species communities were developed. Combining in vivo and in vitro data has led us to construct novel models of how the early canine plaque biofilm develops.

Septic arthritis due to moraxella osloensis in a rhesus macaque (Macaca mulatta)

A 5.5-y-old Chinese-origin female rhesus macaque (Macaca mulatta) presented for bilateral hindlimb lameness. The primate had been group-reared in an SPF breeding colony and was seronegative for Macacine herpesvirus 1, SIV, simian retrovirus type D, and simian T-lymphotropic virus. The macaque's previous medical history included multiple occasions of swelling in the left tarsus, and trauma to the right arm and bilateral hands. In addition, the macaque had experienced osteomyelitis of the left distal tibia and rupture of the right cranial cruciate ligament that had been surgically repaired. Abnormal physical examination findings on presentation included a thin body condition, mild dehydration, and bilaterally swollen stifles that were warm to the touch, with the right stifle more severely affected. Mild instability in the left stifle was noted, and decreased range of motion and muscle atrophy were present bilaterally. Hematologic findings included marked neutrophilia and lymphopenia and moderate anemia. Arthrocentesis and culture of joint fluid revealed Moraxella-like organisms. Treatment with enrofloxacin was initiated empirically and subsequently switched to cephalexin, which over time alleviated the joint swelling and inflammation. Definitive diagnosis of Moraxella osloensis septic arthritis was made through isolation of the organism and sequencing of the 16S rDNA region. To our knowledge, this report is the first description of Moraxella osloensis septic arthritis in a rhesus macaque.

Compartmental syndrome of the upper limb due to Moraxella lacunata infection: a link to patera foot syndrome?

We report a case of compartmental syndrome of the left upper limb secondary to a severe Moraxella lacunata infection, an unusual pathogen, occurring in a young black male immigrant to the island of Gran Canaria, Spain. We propose a pathophysiological relationship with patera foot syndrome.

Three cases of Moraxella osloensis meningitis: a difficult experience in species identification and determination of clinical significance

We had three cases of Moraxella osloensis meningitis. The species identification was impossible by conventional and commercial phenotypic tests. However, we could identify the species using the 16S rRNA gene sequencing. Determination of clinical significance was difficult in one patient. All three patients recovered by appropriate antimicrobial therapy.

Infective endocarditis due to Moraxella lacunata: report of 4 patients and review of published cases of Moraxella endocarditis

Moraxella is an aerobic, oxidase-positive, Gram-negative coccobacillus, which is rarely associated with serious and invasive infections. We describe 4 cases of Moraxella lacunata endocarditis and review 12 previously published cases of Moraxella endocarditis, including 1 further case with M. lacunata, 5 with M. catarrhalis, 2 with M. phenylperuvica and the remainder consisting of 1 case each of M. liquefaciens, M. osloensis, M. nonliquefaciens and 1 non-specified. Of these 16 patients, 5 had prosthetic valves, 5 suffered from an underlying heart abnormality, and the other 6 had normal hearts. Therapy consisted of a beta-lactam antimicrobial and, in several instances, an aminoglycoside as well. The mean duration of antibiotic treatment was 35+/-13 d. Four patients (25%) underwent surgery and 4 out of 16 (25%) died. Moraxella should be added to the growing list of organisms which may occasionally cause infective endocarditis, even in patients without preexisting valvular abnormality.

Invasive infection due to Moraxella lacunata, an unusual pathogen

Moraxella lacunata, a commensal bacterium, is associated with serious invasive disease. We describe a patient with diabetic nephropathy who developed septicemia with metastatic abscesses in the liver and spleen due to Moraxella lacunata. The patient also had multiple ring enhancing lesions in both the cerebral hemispheres, possibly due to the same organism.

Effects of Moraxella (Branhamella) ovis culture filtrates on bovine erythrocytes, peripheral mononuclear cells, and corneal epithelial cells

Infectious bovine keratoconjunctivitis (IBK) is a highly contagious ocular disease that affects cattle of all ages and that occurs worldwide. Piliated hemolytic Moraxella bovis is recognized as the etiologic agent of IBK. According to data from the Nebraska Veterinary Diagnostic Laboratory System, however, Moraxella (Branhamella) ovis has been isolated with increasing frequency from cattle affected with IBK. The objective of this study was, therefore, to examine M. ovis field isolates for the presence of the putative virulence factors of M. bovis. Culture filtrates from selected M. ovis field isolates demonstrated hemolytic activity on bovine erythrocytes and cytotoxic activity on bovine peripheral blood mononuclear cells and corneal epithelial cells. The hemolytic activity of the culture filtrates was attenuated after heat treatment. Polyclonal antibodies raised against the M. bovis hemolysin-cytotoxin also recognized a protein of approximately 98 kDa in a Western blot assay. These data indicate that the M. ovis field isolates examined produce one or more heat-labile exotoxins and may suggest that M. ovis plays a role in the pathogenesis of IBK.

Endotoxin activity of Moraxella osloensis against the grey garden slug, Deroceras reticulatum

Moraxella osloensis is a gram-negative bacterium associated with Phasmarhabditis hermaphrodita, a slug-parasitic nematode that has prospects for biological control of mollusk pests, especially the grey garden slug, Deroceras reticulatum. This bacterium-feeding nematode acts as a vector that transports M. osloensis into the shell cavity of the slug, and the bacterium is the killing agent in the nematode-bacterium complex. We discovered that M. osloensis produces an endotoxin(s), which is tolerant to heat and protease treatments and kills the slug after injection into the shell cavity. Washed or broken cells treated with penicillin and streptomycin from 3-day M. osloensis cultures were more pathogenic than similar cells from 2-day M. osloensis cultures. However, heat and protease treatments and 2 days of storage at 22 degrees C increased the endotoxin activity of the young broken cells but not the endotoxin activity of the young washed cells treated with the antibiotics. This suggests that there may be a proteinaceous substance(s) that is structurally associated with the endotoxin(s) and masks its toxicity in the young bacterial cells. Moreover, 2 days of storage of the young washed bacterial cells at 22 degrees C enhanced their endotoxin activity if they were not treated with the antibiotics. Furthermore, purified lipopolysaccharide (LPS) from the 3-day M. osloensis cultures was toxic to slugs, with an estimated 50% lethal dose of 48 microg per slug, thus demonstrating that the LPS of M. osloensis is an endotoxin that is active against D. reticulatum. This appears to be the first report of a biological toxin that is active against mollusks.

Bacteremia due to Moraxella atlantae in a cancer patient

A gram-negative alkaline phosphatase- and pyrrolidone peptidase-positive rod-shaped bacterium (CCUG 45702) was isolated from two aerobic blood cultures from a female cancer patient. No identification could be reached using phenotypic techniques. Amplification of the tRNA intergenic spacers revealed fragments with lengths of 116, 133, and 270 bp, but no such pattern was present in our reference library. Sequencing of the 16S rRNA gene revealed its identity as Moraxella atlantae, a species isolated only rarely and published only once as causing infection. In retrospect, the phenotypic characteristics fit the identification as M. atlantae (formerly known as CDC group M-3). Comparative 16S rRNA sequence analysis indicates that M. atlantae, M. lincolnii, and M. osloensis might constitute three separate genera within the MORAXELLACEAE: After treatment with amoxicillin-clavulanic acid for 2 days, fever subsided and the patient was dismissed.

Posttrabeculectomy endophthalmitis caused by Moraxella nonliquefaciens

Moraxella nonliquefaciens, a commensal organism of the upper respiratory tract, is generally considered to have low pathogenic potential. We report here two cases of severe endophthalmitis occurring 9 years and 2 months after glaucoma filtration surgery, respectively. Apart from sulfonamide, very low MICs were recorded for several antibiotics tested. Identification was based on phenotypic characteristics in combination with sequencing of the 16S rRNA gene.

Pathogenicity of Moraxella osloensis, a bacterium associated with the nematode Phasmarhabditis hermaphrodita, to the slug Deroceras reticulatum

Moraxella osloensis, a gram-negative bacterium, is associated with Phasmarhabditis hermaphrodita, a nematode parasite of slugs. This bacterium-feeding nematode has potential for the biological control of slugs, especially the grey garden slug, Deroceras reticulatum. Infective juveniles of P. hermaphrodita invade the shell cavity of the slug, develop into self-fertilizing hermaphrodites, and produce progeny, resulting in host death. However, the role of the associated bacterium in the pathogenicity of the nematode to the slug is unknown. We discovered that M. osloensis alone is pathogenic to D. reticulatum after injection into the shell cavity or hemocoel of the slug. The bacteria from 60-h cultures were more pathogenic than the bacteria from 40-h cultures, as indicated by the higher and more rapid mortality of the slugs injected with the former. Coinjection of penicillin and streptomycin with the 60-h bacterial culture reduced its pathogenicity to the slug. Further work suggested that the reduction and loss of pathogenicity of the aged infective juveniles of P. hermaphrodita to D. reticulatum result from the loss of M. osloensis from the aged nematodes. Also, axenic J1/J2 nematodes were nonpathogenic after injection into the shell cavity. Therefore, we conclude that the bacterium is the sole killing agent of D. reticulatum in the nematode-bacterium complex and that P. hermaphrodita acts only as a vector to transport the bacterium into the shell cavity of the slug. The identification of the toxic metabolites produced by M. osloensis is being pursued.

Association of Moraxella ovis with keratoconjunctivitis in mule deer and moose in Wyoming

Six cases of infectious keratoconjunctivitis (IKC) in mule deer (Odocoileus hemionus) and moose (Alces alces) in Wyoming (USA) were investigated during fall and winter of 1995 and 1996. Excessive lacrimation, mucopurulent conjunctivitis, keratitis, and corneal opacity were observed in mule deer. Moose had severe mucopurulent conjunctivitis, keratitis, and corneal ulceration. Hemolytic, non-piliated Moraxella ovis was isolated from two mule deer and two moose. We attempted to reproduce IKC in three mule deer fawns using an isolate of M. ovis from a clinically affected mule deer. These fawns did not develop clinical signs of infection and the bacterium was not reisolated from inoculated deer. Inoculated deer may not have developed clinical signs because deer were not exposed to ultraviolet light or mechanical insult before inoculation. In addition, the isolate used for inoculation may have lost virulence factors through passage, or M. ovis may not have been the primary pathogen responsible for clinical disease in the natural cases of IKC we investigated. The etiology of IKC in free-ranging wild ruminants remains poorly understood.

Kingella kingae intervertebral disk infection

Disk inflammation in children is believed to result from infection, and Staphylococcus aureus is reported to be the organism most commonly isolated from cases of intervertebral disk infection. A case of disk inflammation caused by the unusual pathogen Kingella kingae is described. The antibiotic susceptibility of other K. kingae isolates and the clinical features of 11 other previously reported cases of disk infection caused by this microorganism are reviewed.

Mechanism of action of Moraxella bovis hemolysin

Bovine erythrocytes (RBCs) exposed to Moraxella bovis culture supernatants exhibited rapid leakage of intracellular K+ (95% in 10 min), slower cell swelling (1.20-fold increase in mean corpuscular volume in 20 min), and subsequent lysis (76% leakage of hemoglobin in 25 min). Incubation media made hypertonic by the addition of 75 mM carbohydrates with molecular diameters of 0.72 to 1.32 nm prevented hemolysin-induced RBC swelling, but incubation media made hypertonic by the addition of carbohydrates with molecular diameters of less than 0.72 nm did not protect against hemolysin-induced RBC swelling. Raffinose (75 mM; molecular diameter, 1.14 nm) did not block hemolysin-induced K+ leakage but did block hemolysis. These findings support the hypothesis that hemolysin-induced lysis occurs by colloid-osmotic swelling and are compatible with M. bovis hemolysin acting as a pore-forming cytolysin. Assuming that M. bovis hemolysin acts as a transmembrane molecular sieve, then the functional size of the hemolysin transmembrane pores in bovine RBCs is approximately 0.9 nm, the molecular size of sucrose. Hemolytic activity was inhibited by the Ca2+ chelator ethylene glycol-bis (beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA), but hemolysin-induced K+ leakage was not affected by EGTA.

Effectiveness of two commercial infectious bovine keratoconjunctivitis vaccines

Two commercially available infectious bovine keratoconjunctivitis (IBK) vaccines were evaluated for their effectiveness in protecting cattle from disease caused by experimental challenge exposure and natural transmission of Moraxella bovis infections. The study was conducted as 2 experiments, using a total of 81 cattle that were culture-negative for M bovis prior to vaccination. In each experiment, young adult cattle were randomly allotted to 4 groups. Each calf in groups 1 and 2 was vaccinated according to the vaccine manufacturer's directions. Groups 3 and 4 were unvaccinated controls. Three weeks after the last vaccination, each calf in groups 1 and 3 was experimentally challenge exposed by dropping a suspension of viable cells of a virulent strain of M bovis directly onto the corneal surface of each eye. Calves in all 4 groups were then commingled in open pastures so that calves in groups 2 and 4 could be naturally exposed to the calves with experimentally induced infections. Each calf was examined for signs of ocular disease on a regular basis by 2 experienced clinicians who scored each eye for severity of disease on the basis of a prearranged scale. Neither clinician was aware of the vaccination or exposure status of the calf nor to which experimental group they belonged. Lacrimal secretions were collected regularly to determine the number of eyes in which the virulent organism became established. Moraxella bovis with bacterial cultural characteristics similar to those of the virulent strain placed in the eyes of groups 1 and 3 was cultured from greater than or equal to 83% of the eyes of calves in all groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative characterization of the leukocidic and hemolytic activity of Moraxella bovis

The cytotoxic effect of Moraxella bovis 118F on bovine neutrophils was evaluated and characterized by use of a 51Cr release assay. Neutrophils harvested from healthy adult cattle were labeled with 51Cr. The leukocidic activity produced by M bovis 118F, a hemolytic strain of M bovis, was heat-labile. A live culture of strain 118F, at a ratio of 100 bacteria/neutrophil, released 97.7% of the 51Cr from labeled neutrophils. Neither a heat-killed preparation of M bovis 118F nor a live or heat-killed preparation of M bovis IBH63 (a nonhemolytic and nonpathogenic strain) induced significant (P greater than 0.05) release of 51Cr. Moraxella bovis 118F broth culture filtrates prepared for evaluation of leukocidic activity also were evaluated for hemolytic activity. These 2 toxic activities had several characteristics in common. Both were filterable, heat-labile, produced by a hemolytic strain, and were released during early logarithmic phase growth from broth cultures. Leukocidic and hemolytic activities were protected from degradation by phenylmethyl sulfonyl fluoride, a serine protease inhibitor. Leukocidic and hemolytic activities were dependent on calcium ions. Filtrate resulted in 54.1% 51Cr release from labeled neutrophils and contained 646.7 hemolytic U/ml, respectively, when saline (0.85% NaCl) + 10 mM CaCl2 solution was used as diluent. Neither saline solution nor saline + 10 mM MgCl2 solution supported leukocidic or hemolytic activity. Serum, obtained from several calves 10 to 38 days after M bovis inoculation, substantially neutralized leukocidic and hemolytic activities, compared with paired preinoculation serum samples.(ABSTRACT TRUNCATED AT 250 WORDS)

Biological reactivity of Moraxella bovis lipopolysaccharide

Lipopolysaccharide (LPS) was isolated from Moraxella bovis 118F and ATCC 10900, M ovis ATCC 33078, and M phenylpyruvica ATCC 23333 by hot phenol-water extraction. In silver-stained sodium dodecyl sulfate polyacrylamide electrophoresis gels, M bovis 118F LPS had a smooth profile, whereas the other Moraxella preparations appeared to be rough. The LPS preparations induced pyrogenicity and dermal Shwartzman reactions in rabbits, and induced production of tumor necrosis factor and interleukin-1 in vitro. Induction of tumor necrosis factor appeared to be among the most potent biological activities of M bovis LPS.

Characterization of the plasmids of Moraxella bovis

Restriction endonuclease digestions were performed on plasmids purified from Moraxella bovis isolates GRS, Newport, and IBH64. It was determined from single and double digestions of plasmid DNA that GRS and Newport isolates carried 3 large plasmids having molecular sizes of 43.8, 41.3, and 32.8 kilobases (kb). Digestion of the 3 large plasmids and restriction endonucleases Hae III, HindIII, Nde I, and Ava I strongly indicated that these isolates shared structurally identical large plasmids. Timed single digestions with Ava I revealed that the IBH64 isolate carried 2 large plasmids having molecular sizes of 45 and 32.8 kb. The 32.8-kb plasmid was the only large plasmid that appeared to be shared by all 3 M bovis isolates. Two isolates, Newport and IBH64, carried small plasmids in addition to the large plasmids. Restriction maps were constructed for the 43.8-, 41.3-, and 32.8-kb plasmids.

Infectious bovine keratoconjunctivitis epizootic associated with area-wide emergence of a new Moraxella bovis pilus type

Pilus-mediated adherence is a virulence attribute of Moraxella bovis. Several pilus types have been shown to exist among strains of this bacterium, but correlation between pilus type and specific field cases of the disease has not been done. During the summer of 1987, an epizootic of infectious bovine keratoconjunctivitis was reported in 7 Iowa counties. Eight isolates of M bovis were secured from 12 episodes studied. All 8 of the isolates were nearly homogeneous in biochemical properties and had the same plasmid biotype. Pilus typing performed by immunofluorescence and immunogold electron microscopy identified a single new pilus type among 5 of the 8 isolates. This pilus type was identified in field cases that developed within a narrow time frame and over large distances. The implication of these findings is that infectious bovine keratoconjunctivitis epizootics may be associated with emergence of a novel pilus type, and that rapid dissemination over wide distances can occur, presumably by transportation of carrier cattle.

Infectivity and virulence of Australian strains of Moraxella bovis for the murine and bovine eye in relation to pilus serogroup sub-unit size and degree of piliation

The degree of piliation of 29 haemolytic and 4 non-haemolytic Australian strains of Moraxella bovis representing 7 different pilus antigen groups was determined. The infectivity and virulence for the eye was measured in steroid-treated mice and in cattle. Non-piliated strains failed to infect the murine eye. Most moderately or heavily piliated strains reproducibly produced the highest infectivity and virulence scores in mice when compared with lightly or very lightly piliated strains (p less than 0.05). Non-haemolytic, piliated strains were infective and in one instance virulent for mice. Almost similar levels of infectivity and virulence were observed for 7 representative haemolytic strains tested in both cattle and mice. The relative molecular weight of pilin sub-units was compared using sodium dodecyl-sulphate polyacrylamide gel electrophoresis. Three classes of pili, alpha, beta and gamma of ascending sub-unit size were identified among the 7 pilus antigen serogroups. Pilin sub-unit size bore no relationship to the degree of piliation but most strains that were highly virulent in mice and cattle expressed alpha and gamma sub-units. Some strains appeared capable of switching from alpha to beta or form beta to gamma sub-unit production.

[Species-forming involution of pathogenic bacteria as a biological pattern (exemplified by bacteria of the genus Moraxella)]

The author advances a hypothesis stating that a species disappearing as a result of new conditions evolving in a colonized animal or human body, unfavorable for the existence of this species, does not become extinct, but reverts into newly developing species due to the loss of its properties and acquiring new properties corresponding to new conditions. Thus the genus is preserved through the loss of species characteristics by individual organisms. The advanced hypothesis is substantiated by the analysis of the relevant processes observed in cases of infectious keratoconjunctivitis in humans and cattle, caused by bacteria of the genus Moraxella. The data indicating the possibility of such reversion in the genera Neisseria and Bordetella are presented.

Purification, characterization, and pathogenicity of Moraxella bovis pili

Pilins composed of the alpha or beta pilins of Moraxella bovis strain Epp63 were purified, subjected to chemical or enzymatic cleavage, and the resulting fragments sequenced by automated Edman degradation. alpha Pilin was found to be a 155-amino-acid polypeptide with a single intramolecular disulfide bridge. The beta pilin amino acid sequence substantiated the previously reported structure derived from the beta pilin gene DNA sequence, and indicated that the alpha and beta pilins of this strain are approximately 70% homologous. DNA hybridization studies of genomic DNA from the alpha- and beta-piliated variants of strain Epp63 indicated that the expression of the two pilin types was governed by an oscillating mechanism of chromosomal rearrangement. The alpha and beta pili were evaluated serologically and found to exhibit approximately 50% shared antigenicity, indicating that regions of conserved and heterologous sequence specify both type-specific and crossreacting epitopes. The pathogenicity of the alpha- and beta-piliated variants was studied by ocular inoculation of calves eyes; beta-piliated organisms were significantly more infectious than alpha-piliated organisms, indicating that beta pili confer, or are associated with, a relative advantage during the first stages of ocular infection. Preliminary analysis of other M. bovis strains suggests that each strain produces two types of pilin, and that this property may be characteristic of the species.

Pathogenicity and immunogenicity of piliated and nonpiliated phases of Moraxella bovis in calves

Pathogenicity evaluations of Moraxella bovis strain EPP 63 grown in the piliated and nonpiliated phase indicated that the organism grown in the piliated phase induced clinical keratoconjunctivitis, whereas the organism grown in the nonpiliated phase did not induce disease under identical challenge conditions. Calves inoculated with culture grown in the piliated phase developed significantly (P less than 0.01) higher lesion scores than did calves inoculated with culture grown in the nonpiliated phase. Vaccination/challenge exposure evaluations indicated that calves immunized with vaccine prepared from piliated culture had significantly lower lesion scores than did control calves (P less than 0.001) or calves immunized with vaccine prepared from nonpiliated culture (P less than 0.05). Similarly, calves immunized with piliated vaccine developed a significantly higher antibody titer against purified pili. Nonvaccinated controls and calves immunized with nonpiliated vaccine did not develop a significant increase in antibody titer. The results indicate that M bovis pili constitute an important factor in the pathogenicity of keratoconjunctivitis and may be used as a vaccine in the control of keratoconjunctivitis in cattle.

Mycoplasma bovoculi infection increases ocular colonization by Moraxella ovis in calves

To determine whether infection with Mycoplasma bovoculi increases ocular colonization of cattle eyes with Moraxella bovis and other bacteria, colonization of ocular gram-negative bacteria were measured in eyes of cattle infected with Mycoplasma bovoculi. Strains of Moraxella ovis were chosen because these are among the most commonly isolated species of gram-negative bacteria from cattle eyes. Five strains of M ovis were characterized biochemically and by pilus structure, permitting the recognition of 2 biotypes. All strains were tested in a mouse corneal pathogenicity model. One strain of each biotype was selected for testing in calves. All 5 strains were apathogenic for mice, and the 2 strains tested in cattle did not induce keratitis. Infection of calves with Mycoplasma bovoculi increased the amount and persistence of colonization with the strains of M ovis.

Scanning electron microscopy of bovine corneas irradiated with sun lamps and challenge exposed with Moraxella bovis

Effects of UV radiation and irradiation followed by challenge exposure with Moraxella bovis on the corneal epithelium were studied in 6 calves by scanning electron microscopy. After UV irradiation, the number of dark cells comprising the surface epithelium increased. Many epithelial cells were in various states of degeneration and were characterized initially by large round nuclei, whereas sloughing and peeling were characteristic of the last degenerative stage. All M bovis-infected irradiated eyes had large numbers of degenerating cells, deep epithelial defects, fibrin strands, surface inflammatory cells, and debris. A few M bovis organisms were randomly attached to the cornea before visible ulceration. There were many inflammatory cells between the ulcerated corneal epithelium and adjacent nonulcerated epithelium. Epithelial cells at the margin of the ulcer appeared swollen. Light, dark, and intermediate epithelial cell types could not be distinguished peripheral to the ulcer.

Branhamella catarrhalis bacteraemia and immunosuppression--part of a larger problem?

Attention is drawn to the striking association between bacteraemia due to Branhamella catarrhalis and immunosuppression and evidence is cited suggesting a special relationship between this and other Neisseria of intermediate virulence and systemic disease in the immunologically compromised.

Effects of aflatoxin ingestion on the development of Moraxella bovis infectious bovine keratoconjunctivitis

A study was conducted to determine whether measured doses of aflatoxin given under different schedules would influence the pathogenesis of Moraxella bovis induced infectious bovine keratoconjunctivitis (IBK). Calves were allotted to 4 groups (groups I-IV) of 9, 9, 9, and 8 calves, respectively. Group I calves were given aflatoxin for 11 consecutive days starting 5 days before their eyes were exposed to M. bovis. Group II calves were given aflatoxin for 5 consecutive days starting 7 days after their eyes were exposed to M. bovis. Group III calves were given aflatoxin for 5 consecutive days starting 21 days after their eyes were exposed to M. bovis. Group IV calves were not given aflatoxin; but their eyes were exposed to M. bovis on the same day as were the eyes of calves in groups I-III; these calves served as controls. Aflatoxin had little if any influence on the pathogenesis of IBK under the conditions of this study. The results did not rule out an exacerbating effect of M bovis infection on aflatoxicosis in calves. Calves with the highest concentration of aflatoxin in their blood had the more severe signs of aflatoxicosis. Possible reasons for the equivocal results are discussed.

Genotypic, phenotypic, and biological characteristics of Moraxella bovis

Several isolates of Moraxella bovis obtained from cattle with infectious bovine keratoconjunctivitis killed monocytes and macrophages in vitro and carried 3 to 5 plasmids. Cloned and noncloned M bovis isolates readily induced the disease, killed the phagocytes in vitro, and carried 3 plasmids. Moraxella bovis isolates of low in vivo virulence carried 5 plasmids and did not kill phagocytes to the extent that isolates with 3 plasmids did. The possible implications of these findings in the pathogenesis of infectious bovine keratoconjunctivitis are discussed. Also, a classification of M bovis colonies into rough or smooth varieties according to their staining characteristics with crystal violet is suggested.

Laboratory model for infectious bovine keratoconjunctivitis: the pathogenicity of different strains of Moraxella bovis, pathology and ultrastructural observations

Further studies were made using C57 mice pretreated with a corticosteroid and inoculated with Moraxella bovis by instillation, as a model for infectious bovine keratoconjunctivitis. Strains of M bovis which had previously been tested in cattle produced a generally similar range of pathogenicity when tested in mice. The pathology in the mouse model closely resembled that in cattle and the value of the model for studies on M bovis was confirmed.

Hemagglutination, autoagglutination and pathogenicity of Moraxella bovis strains

Three isolates of Moraxella bovis, recovered from cattle with signs of infectious bovine keratoconjunctivitis, were tested for autoagglutinating activity, hemagglutinating activity and pathogenicity in young calves. Only the autoagglutinating and hemagglutinating isolates were pathogenic in calves. Treatment of the pathogenic isolates with magnesium chloride eliminated their pathogenic effects.

Chronic cholera-like lesions caused by Moraxella osloensis

Cholera-like lesions appeared in four house-confined flocks of tom turkeys on one farm from October 30, 1980, to December 2, 1980; Moraxella osloensis was isolated from the tissues. All flocks were treated with 0.04% sulfaquinoxaline in the water for 3 days. The flocks returned to normal and had normal condemnation rates at slaughter. An experiment was conducted in which six hen turkeys were inoculated with a M. osloensis isolate. The same gross lesions were produced as seen in the field cases.

Isolation of Mycoplasma bovoculi from cases of infectious bovine keratoconjunctivitis

Five outbreaks of infectious bovine keratoconjunctivitis were examined for bacteria and mycoplasmas. Mycoplasma bovoculi was demonstrated in four of the five outbreaks. Other mycoplasmatales were represented by Ureaplasma in one sample. Moraxella bovis and Neisseria ovis were found in all the outbreaks, the former being present in the vast majority of the animals. Transmission experiments with Mycoplasma bovoculi and Moraxella bovis in combination were carried out on four young, colostrumdeprived calves. Mycoplasma bovoculi appeared to have an enhancing effect on the pathogenicity of Moraxella bovis.

Moraxella bacteremia. Report of a case resembling gonococcemia with cutaneous manifestations

A case of a Moraxella osloensis bacteremia mimicking a case of gonococcemia, complete with cutaneous manifestations, is presented. The importance of confirming all positive smears with inhibitory and noninhibitory culture media is stressed.

Pneumonitis and pulmonary abscess associated with Moraxella nonliquefaciens

A 78-year-old man with pneumonitis and pulmonary abscess associated with Moraxella nonliquefaciens is presented. This organism was found by culture of both transtracheal aspirate and sputum. No previous reports have associated M nonliquefaciens with infection of the lower respiratory tract, although sinusitis and bronchitis have been reported. Possible predisposing factors in our patient included carcinoma of the larynx, as well as alcohol ingestion and cigarette smoking.