Rhodococcus equi vertebral osteomyelitis in foals.
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Actinomycetales Infections↗
Biomedical subjects
J F Prescott
Publications and source records attributed to J F Prescott.
Development of reactive arthritis and resistance to erythromycin and rifampin in a foal during treatment for Rhodococcus equi pneumonia.
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Actinomycetales Infections↗
Serological response in sheep vaccinated against Coxiella burnetii (Q fever).
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Animals↗
Outer membrane proteins of three pathogenic Leptospira species.
The outer membrane proteins of seven reference strains of pathogenic Leptospira (L. alstoni serovar grippotyphosa, L. borgpetersenii serovar hardjo, and L. interrogans serovars autumnalis, bratislava, canicola, icterohaemorrhagiae, and pomona) were investigated to identify common surface-exposed outer membrane proteins. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of sodium-N-lauroylsarcosinate-insoluble outer membrane enriched fractions of the reference serovars and two field isolates of serovars hardjo and pomona revealed six common protein bands with approximate molecular masses of 77, 66, 42, 35.5, 24, and 18 kDa. At times the 35.5 kDa endoflagellar band resolved into two distinct bands, 35.5 kDa and 34 kDa. Immunoblotting of the same fractions using rabbit leptospiral antibodies showed six bands to be common (66, 59.5, 44, 42, 35.5, and 18 kDa). The 44 kDa band stained poorly with Coomassie blue but prominently by immunoblotting. Four reference strains (serovars bratislava, canicola, icterohaemorrhagiae, pomona), and two field isolates of serovar pomona and one of serovar bratislava were grown in low iron media to which the iron chelators 2,2'-dipyridyl or ethylenediaminehydroxyphenylacetic acid were added. No iron-dependent expression of outer membrane proteins was observed. The only difference observed between the outer membrane proteins when reference serovars of canicola or pomona were grown in dialysis bags in the peritoneum of swine or in vitro was the loss of the 77 kDa band from in vivo grown organisms. Treatment of whole leptospires with proteinase K did not remove the 77, 66, 59.5, or 42 kDa protein; these proteins may not be surface expressed or are inaccessible to the proteinase K. The 44 kDa band could not be evaluated by this method and the 18 kDa band was proteinase K resistant.
Animals↗
Rhodococcus equi.
This article summarizes recent advances in understanding of the epidemiology, pathogenesis, clinical and laboratory diagnosis, immunology, treatment, and control of Rhodococcus equi infections in foals. Our understanding of these aspects currently is sufficient to ensure control of this problem on affected farms and in infected foals. More information, however, is needed on factors predisposing foals to R. equi pneumonia, in particular, the nature of the naturally occurring cellular immunodeficiency in foals of 2 to 4 months of age, which also predisposes them to severe respiratory infection with certain other intracellular pathogens. In addition, the relative importance of R. equi pneumonia in the context of other causes of lower respiratory tract infection of foals needs to be defined.
Actinomycetales Infections↗
Immunodeficiency and serious pneumonia in foals: the plot thickens.
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Actinomycetales Infections↗
Clinical and endoscopic study to estimate the incidence of distal respiratory tract infection in thoroughbred foals on Ontario breeding farms.
Respiratory tract infections are prevalent in foals, yet the frequency with which the distal airways are affected in clinical episodes of respiratory tract disease has not been evaluated to our knowledge. The objective of the study was to determine the incidence of distal respiratory tract infection (DRTI) in foals on a sample of Thoroughbred breeding farms (n = 10) in Ontario. In a pilot study, clinical criteria commonly used to select foals for antimicrobial treatment (detection of abnormal lung sounds, plus nasal discharge, cough, fever, tachypnea, and/or lethargy) were found to segregate foals with and without endoscopically confirmed DRTI. Mucopurulent exudate and bronchial erythema were observed more frequently (P < 0.005), bronchial lavage total cell count and neutrophil concentration were significantly (P < 0.005) higher, and intracellular cocci were recovered significantly (P < 0.01) more often from bronchial lavage samples of affected foals (n = 8) than of controls (n = 8). These clinical criteria were used to identify cases in a cohort of Thoroughbred foals (n = 219) from May 1 to October 30, 1991. Case morbidity adjusted for clustering was 82 +/- 5% (95% confidence limits, 72 to 92%). Most (74%) episodes of clinical DRTI were detected in July and August, and equal numbers were detected before (53%) and after (47%) weaning of foals. Of 178 cases, 66 (48%) were selected at random for endoscopy and bronchial lavage. Grade-II pharyngeal lymphoid hyperplasia was observed commonly (60% of foals); auditory tube diverticulum (guttural pouch) discharge was observed in 18 of 86 (21%) foals, and guttural pouch infection was confirmed in 6 of 7 foals examined endoscopically.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Microbiologic changes during antimicrobial treatment and rate of relapse of distal respiratory tract infections in foals.
Despite the high incidence of distal respiratory tract infection of undetermined cause on farms, to our knowledge, the microbiologic effects of conventional antimicrobial treatment for this condition have not been studied. We evaluated the possible pathogenic role of bacterial isolates from the distal airways of foals with clinical respiratory tract disease, by correlating changes in their numbers (increase or decrease) with clinical, endoscopic, and pulmonary cytologic signs of disease resolution during treatment with antimicrobial drugs. We also determined qualitative changes in in vitro antimicrobial susceptibility of bacterial isolates after 7 days of treatment and relapse rate of foals. Significant (P < 0.05) decrease in the numbers of an isolate in the airways was considered strong evidence of a pathogenic role in this disease syndrome. Foals with endoscopically confirmed distal respiratory tract infection (DRTI; n = 65) were selected at random for treatment (n = 56) or nontreatment (n = 9), and bronchial lavage specimens were cultured and evaluated cytologically before and after 7 days of treatment with trimethoprim-sulfamethoxazole (TMS) and a beta-lactam drug (penicillin, ampicillin, or sulbactam-ampicillin), the standard treatment in all foals. The effect of treatment was to abruptly reduce the clinical (nasal discharge, cough, adventitious lung sounds) and cytologic signs of airway infection. Severity of disease in nontreated foals, however, did not change or did worsen over time. Reduction in the frequency and numbers of Streptococcus zooepidemicus isolated during treatment supported a causal role for this organism in the clinical syndrome observed.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Association of microbiologic flora with clinical, endoscopic, and pulmonary cytologic findings in foals with distal respiratory tract infection.
Undifferentiated distal respiratory tract disease (nasal discharge, cough, pneumonia) in foals (1 to 8 months old) is a burdensome economic problem on breeding farms; yet, the infective agents associated with these episodes have not been well described. Possible causes of these episodes of illness were investigated by culturing specimens of proximal and distal airways of clinically diseased foals (n = 101), prior to any treatment, for aerobic and anaerobic bacteria and viruses (rhinoviruses, equine arteritis virus, equine herpesvirus subtype 1 [EHV-1], influenza virus, and adenovirus). Pairs of sera (n = 47) were examined for antibodies to influenza A virus, equine subtypes 1 and 2, EHV-1, and adenovirus antigens, and sera obtained from foals during acute infection were examined for antibodies (by agar gel immunodiffusion [AGID]) to equi factor antigens of Rhodococcus equi. Viruses were not isolated from the proximal (swab) or distal (bronchial lavage) airway specimens in foals, and only 2 of 47 randomly selected foals seroconverted to EHV-1. Serotiters to the other viruses were low and frequently decreasing between samples, which was compatible with maternally derived antibody. Streptococcus zooepidemicus was the predominant isolate from bronchial lavage specimens (88/101 cases), accompanied by alpha-hemolytic streptococci (8 cases), Bordetella bronchiseptica (13 cases), Staphylococcus epidermidis (9 cases), and other organisms in lesser frequency. Only Str zooepidemicus was recovered significantly (P < 0.05) more often in cases than in controls. The AGID test was found useful to detect foals with presumed exposure to R equi, but positive tests results did not correspond well with bacterial culture results; positive AGID results were recorded in 34% of culture-negative foals.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Serodiagnosis of leptospirosis in pigs using an axial filament enzyme-linked immunosorbent assay.
The axial filament (AF) from Leptospira interrogans serovar canicola was isolated by cesium chloride density gradient centrifugation of 2% sarcosyl treated whole cells. Isolation of AF was confirmed by electron microscopic examination, by protein-A immunogold labelling, sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE), and immunoblotting. Analysis by SDS-PAGE of the purified preparation showed relatively weak bands of molecular size 41 kDa and 21 kDa, and strong bands of 35 kDa and 34.5 kDa. Immunoblot analysis using antiserum to the AF against sonicated leptospires of a variety of serovars showed prominent reaction against the 41, 35, and 34.5 kDa protein bands, as well as against minor bands of molecular weight 43, 39, and 37 kDa. Antisera prepared against leptospiral serovars also identified minor bands at 33 and 32 kDa. Immunoblots with antiserum to whole cells of serovar bratislava detected the 35 and 34.5 kDa AF bands of Borrelia burgdorferi moderately and of Treponema hyodysenteriae only slightly in comparison to leptospiral AF. Antibody to B. burgdorferi did not detect the leptospiral AF antigen. Immunoblots with antiserum to T. hyodysenteriae showed a marked reaction with a 41 kDa band of B. burgdorferi but only a very minor reaction with leptospiral AF. The AF was tested in an AF-ELISA against sera from 260 pigs, many of which reacted in the microscopic agglutination test (MAT) against one or more leptospiral serovars. A sensitivity of 97.1% and a specificity of 93.1% was determined in comparison to the MAT. Only moderate correlation was observed between titres detected in the AF-ELISA and the MAT (r = 0.4). When sonicated whole cells (WC) of serovar canicola were used in an ELISA (WC-ELISA), high correlation was observed between AF-ELISA and WC-ELISA (r = 0.97). These findings show that the AF-ELISA can be used effectively as a species-specific antigen for the serological diagnosis of leptospirosis in swine and that sonicated whole cells can substitute excellently for purified AF as the antigen source. These findings may be extrapolated to the use of AF in immunodiagnosis of leptospirosis in other species.
Agglutination Tests↗
Immunoblot analysis of the humoral immune response to Pythium insidiosum in horses with pythiosis.
Reactions to Pythium insidiosum by sera from horses with active pythiosis were investigated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunoblotting. Five strains of P. insidiosum were grown in nutrient broth and then sonicated. After centrifugation, supernatant antigens were separated by SDS-PAGE. An exoantigen of Conidiobolus coronatus was also tested. Bands with molecular weights between 97,000 and 14,000 were identified by Coomassie blue and silver staining. After being transferred to nitrocellulose, the antigens were reacted against sera from six horses with pythiosis, sera from four horses cured a year earlier by vaccination, and sera from five healthy horses. The sera from horses with pythiosis recognized at least 20 antigens in all strains. Three antigens with molecular weights of 32,000, 30,000, and 28,000 appeared to be immunodominant and specific. Sera from horses cured by immunotherapy showed only five very weak bands, three of them the 32,000-molecular-weight (32K), 30K, and 28K antigens. No bands were observed with sera from healthy horses or sera from horses with a variety of other infections. Sera from horses with pythiosis cross-reacted with the 44K antigen of C. coronatus. The immunodominant antigens described here may be useful for diagnostic purposes and in immunotherapy for this oomycotic infection in horses.
Animals↗
Use of bacitracin in the prevention and treatment of experimentally-induced idiopathic colitis in horses.
Ten healthy ponies from a single herd were found by repeated fecal culture to be free of Salmonella species and Clostridium cadaveris. In a preliminary study, four ponies administered a single oral dose of 10 mg/kg lincomycin did not develop idiopathic colitis when the drug was administered alone. Four other ponies were administered 10 mg/kg lincomycin by stomach tube together with 0.45 L of colonic content from a horse with idiopathic colitis induced earlier by lincomycin alone. Two of the four ponies were treated with 25 g oral zinc bacitracin premix (110 g/kg active ingredient) 24 h later. Forty-two hours after inoculation the two untreated ponies had severe signs of idiopathic colitis and were euthanized. Postmortem findings were typical of idiopathic colitis. The two treated ponies had milder illness but the more severely affected was also euthanized; the other was retreated at 42 h with bacitracin pre-mix and again 12 h later. Its illness and diarrhea resolved over the next 24 h. Clostridium cadaveris was isolated in large numbers from the cecum of the euthanized ponies and their cecal content contained mouse lethal and guinea pig dermonecrotic, but not cytotoxic, activity. Enterotoxins of Clostridium perfringens and Clostridium difficile could not be demonstrated. No toxin could be demonstrated in culture supernatants of C. cadaveris or in supernatants of cecal contents treated with ethanol prior to culturing in anaerobically incubated broth. No Salmonella spp. were isolated. A further two ponies were administered 10 mg/kg lincomycin orally with 0.45 L colonic content from a horse with idiopathic colitis, as described.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Lincomycin-induced severe colitis in ponies: association with Clostridium cadaveris.
Four groups of two ponies, free of fecal Salmonella and Clostridium cadaveris, were treated as follows: Group A, control group; B, single nasogastrically administered dose of lincomycin (25 mg/kg) followed 48 h later by 3 L of C. cadaveris (10(9) organisms/mL); C, the same dose of lincomycin as group B; D, the same dose of C. cadaveris as group B on each of three occasions at 12 h intervals. Groups A and D remained healthy, but groups B and C developed severe colitis 48-56 h (B) or 72 h (C) after administration of lincomycin. Three ponies were euthanized and one in group B died. Clostridium cadaveris was isolated at about 10(6)/mL of colonic contents from these ponies, but one pony in group B also yielded Salmonella typhimurium from the colon. Subsequent challenge of group A ponies (3 L of C. cadaveris 10(9)/mL, three times at 12 h intervals) did not produce colitis. Nasogastric administration of lincomycin (25 mg/kg) to group A and D ponies, 20 days after administration of C. cadaveris, resulted in severe colitis in all ponies within 48-72 h. Salmonella agona was isolated from the colonic contents of one pony and C. cadaveris (10(6)/mL) from all four ponies. Clostridium cadaveris was not isolated from the colonic content of 45 healthy horses examined immediately after death. These studies confirm the potential for lincomycin to induce severe enterocolitis in ponies and implicate C. cadaveris further as a cause of "idiopathic colitis" in ponies.
Animals↗
Role of antibody to extracellular proteins of Rhodococcus equi in protection against R. equi pneumonia in foals.
Rhodococcus equi produces two exoenzymes (REE), a cholesterol oxidase in large amounts and a phospholipase C, which cause lysis of sheep red blood cells (SRBC) sensitized with Staphylococcus aureus beta toxin. Two immunization studies were done in foals to determine the role of antibody to REE in protection against R. equi pneumonia. In the first study, three foals (mean age 10 days) were vaccinated four times at 2-week intervals with over 1 million units of partially purified exoenzymes (PREE). In the second study, three foals (mean age 19 days) were administered plasma from an adult horse vaccinated with PREE. Relatively low titres (16-32) of neutralizing antibody were detected in the foals of the former group, and passive transfer of neutralizing antibody (titres 32-64) occurred in the latter. Following immunization, principal foals and an equal number of similarly aged nonimmunized foals were challenged by aerosol with 1 x 10(10) live R. equi per day for 5 consecutive days. No severe clinical pneumonia developed in either group and, with one exception, only minor and resolving lung abscesses developed in these foals. These studies showed that antibody response of foals to immunization with PREE was poor, antibody to PREE did not prevent foals from developing lung abscesses following experimental infection, and that foals even as young as 3 weeks of age may be largely refractory to aerosol challenge with virulent R. equi.
Actinomycetales Infections↗
Rhodococcus equi: an animal and human pathogen.
Recent isolations of Rhodococcus equi from cavitatory pulmonary disease in patients with AIDS have aroused interest among medical microbiologists in this unusual organism. Earlier isolations from humans had also been in immunosuppressed patients following hemolymphatic tumors or renal transplantation. This organism has been recognized for many years as a cause of a serious pyogranulomatous pneumonia of young foals and is occasionally isolated from granulomatous lesions in several other species, in some cases following immunosuppression. The last decade has seen many advances in understanding of the epidemiology, pathogenesis, diagnosis, treatment, and immunity to infection in foals. The particular susceptibility of the foal is not understood but can be explained in part by a combination of heavy challenge through the respiratory route coinciding with declining maternally derived antibody in the absence of fully competent foal cellular immune mechanisms. R. equi is largely a soil organism but is widespread in the feces of herbivores. Its growth in soil is considerably improved by simple nutrients it obtains from herbivore manure. About one-third of human patients who have developed R. equi infections had contact in some way with herbivores or their manure. Others may have acquired infection from contact with soil or wild bird manure. R. equi is an intracellular parasite, which explains the typical pyogranulomatous nature of R. equi infections, the predisposition to infection in human patients with defective cell-mediated immune mechanisms, and the efficacy of antimicrobial drugs that penetrate phagocytic cells.
Acquired Immunodeficiency Syndrome↗
Purification and properties of cholesterol oxidase and choline phosphohydrolase from Rhodococcus equi.
Cholesterol oxidase (CO) and choline phosphohydrolase (CPH) exoenzymes were isolated from culture supernatants of Rhodococcus equi ATCC 33701 and their hemolytic and cytotoxic activities examined. The purifications involved differential ammonium sulphate precipitation, ion exchange and gel filtration chromatography. A purification of 32.8-fold and a yield of 0.3% of CO were determined by synergistic hemolysis of sheep red blood cells (SRBC) presensitized with Staphylococcus aureus beta toxin. The enzymatic activity of CO was also demonstrated by oxidation of aqueous cholesterol suspensions. The activity of CO was reversibly inhibited by concentration. A purification of 412.4-fold and a yield of 1.7% of CPH were determined by hydrolysis of p-nitrophenyphosphorylcholine. Purity of both exoenzymes was confirmed by immunoblotting. On sodium dodecyl sulphate polyacrylamide gel electrophoresis, the CO had a molecular mass (Mr) of 60 kd and the CPH a Mr of 65 kd. Choline phosphohydrolase did not hydrolyse sphingomyelin. Sphingomyelinase C (SMC) activity was however demonstrated in concentrated culture supernatants. This dissociation of SMC from CPH activity indicates that R. equi produces two distinct phospholipase C exoenzymes, a CPH and a SMC. Both CO and CPH combined, or individually, did not lyse native SRBC even with subsequent chilling of the cells at 4 degrees C ("hot-cold" treatment). Purified CO lysed beta toxin-sensitized SRBC. The CPH showed only minor hemolytic activity against such sensitized SRBC even at high concentrations. Combination of CO and CPH in lysis of beta toxin sensitized SRBC showed only minor additive rather than synergistic effects.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Differences in signs and lesions in sheep and goats with enterotoxemia induced by intraduodenal infusion of Clostridium perfringens type D.
Enterotoxemia was induced in 4 lambs and 4 goat kids by continuous intraduodenal infusion of a whole culture of Clostridium perfringens type D. Clinical signs, hematologic values, biochemical alterations, and postmortem lesions in the lambs and goat kids were compared. The 4 lambs and 4 goat kids died within 25 hours of beginning the infusions. Lesions were not observed in the gastrointestinal tract of the 4 lambs; however, severe hemorrhagic enterocolitis was found in the 4 goat kids. This difference between the lambs and goat kids in the lesions caused by experimentally induced enterotoxemia may explain the discrepancies reported between sheep and goats in clinical signs, response to treatment, and efficacy of vaccination observed in naturally induced enterotoxemia in the 2 species.
Animals↗
Field evaluation of a commercial M-protein vaccine against Streptococcus equi infection in foals.
A double-blind randomized clinical trial was undertaken to determine the value of parenterally administered Streptococcus equi M-protein vaccine in foals during an epizootic of strangles. Weaned mixed-breed foals (n = 664) housed on 2 adjacent feed-lots (A and B) arrived over a 5-day period, 2 weeks before primary vaccination. Foals in lot B (n = 114) were randomly administered vaccine (n = 59) or saline solution (placebo; n = 55) on 3 occasions at biweekly intervals. Foals in lot A (n = 450) were given 1 dose of vaccine (n = 225) or placebo. The following clinical observations were scored blindly by a single observer for all foals in lot B and for 120 (randomly sampled) foals in lot A on a single day, 2 (Lot B) and 6 (lot A) weeks after final vaccination: cervical lymphadenopathy, type of bilateral nasal discharge, and palpable swelling at injection site(s). Bacteriologic culture of nasal swab specimens or lymph node aspirates from selected foals with clinical disease yielded S equi. Cervical lymphadenopathy was observed in 17 of 59 (29%) vaccinates and 39 of 55 (71%) nonvaccinated controls in lot B and in 32 of 60 (53%) vaccinates and 29 of 60 (48%) controls in lot A. Contingency chi 2 analysis confirmed significantly lower cervical lymphadenopathy rate (chi 2 = 18.5; P less than 0.001) and prevalence of mucopurulent nasal discharge (chi 2 = 11.4; P less than 0.01) for vaccinates in lot B only. Swelling(s) at the vaccine injection site were palpated in 44% of lot B and 29% of lot A vaccinates vs less than 2% of placebo controls.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗