Streptococcus Equi Subsp Zooepidemicus Research Articles

Factors Associated with Survival in 97 Horses with Septic Pleuropneumonia.

BackgroundSeptic pleuropneumonia is a common cause of morbidity and mortality in horses, but there is limited data available regarding factors associated with survival.Hypothesis/ObjectivesTo identify factors predictive of survival in horses with septic pleuropneumonia.AnimalsA total of 97 horses with septic pleuropneumonia at 2 referral institutions.MethodsA retrospective study was performed. A diagnosis of septic pleuropneumonia was based on the presence of sepsis, pleural effusion, and positive bacterial culture from tracheal aspiration (TA) or pleural fluid (PF).ResultsThirty‐one percent of horses had a recent history of travel. Clinical signs included lethargy (78%), tachycardia (75%), tachypnea (60%), fever (43%), prolonged capillary refill time (22%), and ventral edema (14%). The most common clinicopathologic abnormality was hyperfibrinogenemia (79%). Increased serum creatinine concentration at presentation was negatively associated with survival (OR, 5.13; CI, 1.88–14.01; P = .001) and return to work (OR, 6.46; CI, 1.10–37.92; P = .034). Eighty‐four TA and 67 PF samples were submitted for culture, 98 and 84% of which were positive, respectively. The most common isolate was Streptococcus equi subsp zooepidemicus. Tracheal aspirates were more sensitive than PF for bacterial growth, but some organisms isolated from PF were not isolated from TA. Thoracotomy was positively associated with survival (OR, 0.13; CI, 0.01–0.83; P = .028).Conclusions and Clinical ImportanceIncreased serum creatinine concentration is a negative prognostic indicator and is likely a reflection of dehydration. Submission of TA and PF is recommended. Thoracotomy should be considered as a treatment for pleuropneumonia.

The arginine deiminase system facilitates environmental adaptability of Streptococcus equi ssp. zooepidemicus through pH adjustment

The arginine deiminase system (ADS) is a secondary metabolic system found in many different bacterial pathogens and it is often associated with virulence. Here, a systematic study of ADS functions in Streptococcus equi subsp. zooepidemicus (SEZ) was performed. Transcriptional levels of ADS operon genes were observed to be significantly increased when SEZ was grown under acidic conditions. We constructed arcA and arcD deletion mutants (SEZ ΔarcA and SEZ ΔarcD, respectively) and found that SEZ ΔarcA was unable to metabolize arginine and synthesize ammonia; however, arcD deletion resulted in an initial decrease in arginine consumption and ammonia production, followed by recovery to the levels of wild-type SEZ after 24 h of cultivation. Cell extracts of SEZ ΔarcA showed no arginine deiminase (AD) activity, whereas no difference in AD activity between SEZ ΔarcD and wild-type SEZ was observed. SEZ survival tests demonstrated a significant decrease in survival for SEZ ΔarcA, when compared with wild-type SEZ, under acidic conditions and in epithelial cells. These findings indicate that ADS in SEZ contributes to environmental adaptability via ammonia synthesis to reduce pH stress.

Kinetic of biofilm formation by Streptococcus equi subsp zooepidemicus

Kinetic of biofilm formation by Streptococcus equi subsp zooepidemicus

A randomized controlled field trial of a novel trimethoprim-sulfadiazine oral suspension for treatment of Streptococcus equi subsp zooepidemicus infection of the lower respiratory tract in horses.

To evaluate the effectiveness of a novel trimethoprim-sulfadiazine oral suspension for the treatment of naturally acquired Streptococcus equi subsp zooepidemicus infection in horses. Randomized, controlled field trial. 180 horses with S equi subsp zooepidemicus infection. Horses with lower respiratory tract infections caused by S equi subsp zooepidemicus were treated with a new formulation of combined trimethoprim-sulfadiazine oral suspension at a dosage of 24 mg/kg (10.9 mg/lb) twice daily for 10 days (treatment group) or with an equivalent volume of saline (0.9% NaCl) solution (placebo group). Response to treatment, including clinical signs and fecal consistency scores, was assessed twice daily. Any adverse effects were recorded. The primary outcome variable was clinical response; the secondary outcome variable was eradication of S equi subsp zooepidemicus on study day 17 as determined by bacteriologic culture of repeated transtracheal-wash specimens. Of the 119 horses allocated to the treatment group, 69 (58%) had a positive clinical response. A significantly smaller proportion of horses in the placebo group (9/61 [15%]) had a positive clinical response. By day 5, 25 of 61 (41%) placebo horses had been withdrawn from the study because of negative clinical response, compared with only 10 of 119 (8.4%) treated horses. By day 10, 28 of 61 (46%) placebo horses had been withdrawn because of negative clinical response, compared with only 13 of 119 (11%) treated horses. There were few adverse events associated with the trimethoprim-sulfadiazine suspension. There were no significant differences in fecal consistency scores between treatment and placebo groups. The new oral suspension administered at 24 mg/kg twice daily effectively treated the clinical signs of S equi subsp zooepidemicus lower respiratory infection in horses and eliminated the organism from the respiratory tract. Adverse effects were minimal.

Uterine bacterial isolates from mares and their resistance to antimicrobials: 8,296 cases (2003–2008)

To describe bacteria isolated from reproductive tracts of mares and to examine the extent and patterns of resistance to antimicrobials commonly used for treatment of endometritis. Retrospective case series. 8,296 uterine swab, lavage, or biopsy samples obtained between January 2003 and December 2008 from 7,665 horses in central Florida. Results of bacterial culture and antimicrobial susceptibility testing were obtained for uterine swab, lavage, and biopsy samples collected from mares undergoing a routine breeding examination or examined because of a reproductive disorder. Bacterial organisms were identified by means of standard techniques, and proportions of samples resistant to various antimicrobials were determined. At least 95% of samples (n = 1,451) were collected with uterine swabs. Potentially pathogenic organisms were cultured from 2,576 (31%) samples, with Escherichia coli (n = 729 [29%]) and β-hemolytic Streptococcus equi subsp zooepidemicus (733 [28%]) being most common. Resistance to antimicrobials changed over time for E coli, S equi subsp zooepidemicus, and Enterobacteriaceae isolates. Overall, E coli was most resistant to trimethoprim-sulfonamide and ampicillin and least to amikacin and enrofloxacin. For S equi subsp zooepidemicus, resistance was greatest to oxytetracycline and enrofloxacin and least to ceftiofur and ticarcillin with or without clavulanic acid. Inflammatory response was greater for S equi subsp zooepidemicus. E coli and S equi subsp zooepidemicus were the most common pathogens recovered from uterine samples, with S equi subsp zooepidemicus more commonly associated with inflammation. Antimicrobials most commonly used empirically to treat endometritis are appropriate on the basis of these data. However, as antimicrobial resistance changes over time, susceptibility assays should aid antimicrobial selection.

Comparison of endometrial inflammation following intrauterine inoculation with genital strains of Streptococcus equi subsp zooepidemicus or Escherichia coli in the mare

Comparison of endometrial inflammation following intrauterine inoculation with genital strains of Streptococcus equi subsp zooepidemicus or Escherichia coli in the mare

Characterization of the new β-glucuronidase from Streptococcus equi subsp. zooepidemicus

Recently, a new gene encoding beta-glucuronidase from Streptococcus equi subsp. zooepidemicus (SEZ) was identified and expressed in Escherichia coli. In this paper, the characterization of the enzyme is described. Specific enzyme activity was 120,000 U/mg purified protein at 37 degrees C and pH = 7.0. The temperature and pH value, at which the enzyme has the highest specific activity, were determined and were found to be approximately 52 degrees C and 5.6, respectively. The mutant strain SEZ glcHis was designed for the efficient isolation of beta-glucuronidase from S. equi subsp. zooepidemicus. It was observed that the specific activity of beta-glucuronidase in the cytoplasmic extract of a mutated strain was about 45% lower than in the cytoplasmic extract of a wild-type strain. The specific activity of purified beta-glucuronidase from SEZ glcHis was four times as low as beta-glucuronidase purified from E. coli. Comparing the specific activity of purified streptococcal beta-glucuronidase from E. coli with E. coli beta-glucuronidase (the enzyme with the highest specific activity was supplied by Sigma), the former is 1.8 higher than the latter.

Identification of variations in SzP proteins of Streptococcus equi subspecies zooepidemicus and the relationship between protein variants and clinical signs of infection in horses.

To determine whether previously unidentified variations of the SzP protein of Streptococcus equi subsp zooepidemicus were present in horses with various clinical signs of infection and whether any relationship could be identified between SzP protein variants and naturally occurring clinical conditions. 23 isolates of S equi subsp zooepidemicus were recovered from specimens of horses with various clinical conditions and used as a representative population of isolates for evaluation of different SzP protein variants. Genetic heterogeneity of the isolates was demonstrated by repetitive extragenic palindromic-polymerase chain reaction analysis. The SzP gene was sequenced and the presumed protein sequence determined for each isolate. Characteristics of the SzP proteins were compared among the isolates and in relation to the clinical conditions of horses from which they were recovered. The signal peptide types, number of proline-glutamic acid-proline-lysine repeats, and anchor sequences were consistent with those previously described for the SzP protein. Many of the isolates clustered with 5 previously described types on the basis of the hypervariable region of the SzP protein. One additional variant, which represented 8 of the isolates, was identified. Particular motifs in the hypervariable region accounted for many of the differences among hypervariable types. The SzP protein appears to be limited to a selected number of types. Variations in the SzP protein are frequently determined on the basis of different motifs rather than random amino acid substitutions. There does not appear to be any association of SzP protein variations and clinical manifestations of infection in horses.

Bacterial infection of the lower respiratory tract in 34 horses.

To investigate associations between the bacteriology and aspects of history, clinical presentation, outcome and pathology of lower respiratory tract disease of 34 horses. Detailed aerobic and anaerobic bacteriological investigations were performed on clinical specimens from horses with pneumonia, lung abscessation and necrotic pneumonia with or without pleurisy in an attempt to identify those bacteria that might contribute to the initiation and progression of infection. Bacteria were cultured from 33 of the 34 horses. In ten cases, only aerobic/facultatively anaerobic isolates were cultured while aerobic/facultatively anaerobic bacteria and obligately anaerobic bacteria were isolated in the other 23 cases. Moderate to large numbers of anaerobic bacteria were isolated only when the estimated duration of illness was at least five days. Bacteria were not cultured from 12 of the pleural fluid samples but were always cultured from pulmonary samples (either transtracheal aspirates from live horses or pulmonary lesions at necropsy). Streptococcus equi subsp zooepidemicus was isolated in the three cases where only one bacterial species was cultured. In the other 30 cases, multiple species were isolated. These included most often and in greatest numbers, Streptococcus equi subsp zooepidemicus, Pasteurellaceae, Escherichia coli, anaerobic cocci, Eubacterium fossor, Bacteroides tectum, Prevotella heparinolytica, Fusobacterium spp, and pigmented members of the genera Prevotella and Porphyromonas. Aerobic/facultatively anaerobic organisms were isolated from 97% of horses, while obligately anaerobic organisms were cultured from 68% of horses. There was no association between the isolation of any specific bacterium and the outcome of disease. However, obligately anaerobic bacteria (such as anaerobic cocci, Bacteroides tectum, P heparinolytica and Fusobacterium spp) and the facultatively anaerobic species Escherichia coli, were recovered more commonly from horses that died or were euthanased than from those that survived. There was an association between failure of horses to recover from pleuropneumonia and delay in diagnosis and initiation of treatment.

Acute hemorrhagic pulmonary infarction and necrotizing pneumonia in horses: 21 cases (1967-1993)

Objective— To characterize history, clinical signs, and pathologic findings in horses with histologically confirmed acute hemorrhagic pulmonary infarction and necrotizing pneumonia. Design— Retrospective study. Animals— 21 horses. Results— 19 of the 21 horses were Thoroughbred racehorses in training. Eighteen horses had had strenuous exercise immediately prior to onset of illness. Fifteen horses had a serosanguineous nasal discharge during hospitalization. Seventeen horses had radiographic evidence of pulmonary consolidation and pleural effusion. Nine of 14 horses had ultrasonographic evidence of large pulmonary parenchymal defects consistent with consolidation. Pleurocentesis yielded a suppurative, serosanguineous effusion in the 14 horses in which it was performed. Bacteria were isolated from all transtracheal aspirates (14) and from 6 of 12 pleural fluid samples. Actinobacillus suis-like organisms and Streptococcus equi subsp zooepidemicus were most commonly isolated. Nineteen horses were hospitalized and treated, Mean duration of treatment was 5 days, and most horses were euthanatized because of secondary complications, continued costs of medical treatment, or poor prognosis for future performance. Pathologic lesions included well-demarcated regions of hemorrhagic pulmonary infarction with necrosis and a serosanguineous pleural effusion. Thrombosis of pulmonary vessels was found in 11 horses. Clinical Implications— An acute or peracute onset of severe respiratory distress, with serosanguineous nasal discharge, ultrasonographic and radiographic evidence of severe pulmonary consolidation, and serosanguineous suppurative pleural effusion, is strongly suggestive of pulmonary infarction in horses. Horses with pulmonary infarction responded poorly to conventional treatment for pleuropneumonia and had a poor prognosis for recovery. (J Am Vet Med Assoc 1997;210:1774–1778)