Retrospective study of fatal pneumonia in racehorses.

Respiratory diseases have a major impact on racehorses in training and are often cited as the second most common reason of horses failing to perform. Cases were submitted by the California Horse Racing Board to the California Animal Health and Food Safety laboratory for postmortem examination between January 1, 2005 and December 31, 2014. We determined the demographics of racehorses with fatal pneumonia, characterized the pathologic findings in animals with a postmortem diagnosis of respiratory infection, and determined the most significant pathogens associated with lower respiratory tract disease. We analyzed autopsy reports from 83 horses with a diagnosis of pneumonia, bronchopneumonia, and/or pleuropneumonia. The most common presentation was pleuropneumonia (71% of cases), with extensive areas of lytic necrosis and abscesses of the pulmonary parenchyma. Streptococcus equi ssp. zooepidemicus, a normal mucosal commensal of the upper respiratory tract of healthy horses, was the most commonly isolated organism (72% of cases), either in pure culture or accompanied by other aerobic or anaerobic bacteria. Its presence in the pulmonary parenchyma is associated with severe and extensive damage to the lung. Furthermore, this agent has zoonotic potential, which stresses the importance of early detection and proper management of cases of pneumonia in racehorses.

Factors Associated with Survival in 97 Horses with Septic Pleuropneumonia.

BACKGROUND: Septic pleuropneumonia is a common cause of morbidity and mortality in horses, but there is limited data available regarding factors associated with survival. HYPOTHESIS/OBJECTIVES: To identify factors predictive of survival in horses with septic pleuropneumonia. ANIMALS: A total of 97 horses with septic pleuropneumonia at 2 referral institutions. METHODS: A 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). RESULTS: Thirty-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 IMPORTANCE: Increased 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.

Optimization of immune strategy for a construct of Salmonella-delivered ApxIA, ApxIIA, ApxIIIA and OmpA antigens of Actinobacillus pleuropneumoniae for prevention of porcine pleuropneumonia using a murine model.

In this study, the Actinobacillus pleuropneumoniae antigens ApxIA, ApxIIA, ApxIIIA and OmpA were expressed in an attenuated strain of Salmonella (∆lon∆cpxR∆asd) for prevention of porcine pleuropneumonia. In order to evaluate the immunization strategy of the construct, a total 60 BALB/c mice were equally divided into four groups (n = 15). Group A mice were intranasally immunized only at 6-weeks-of-age, while group B mice were intransally primed and boosted at 6- and 9-weeks-of-age, respectively, and group C mice were intransally primed at 6-weeks-of-age and subsequently boosted twice at 9- and 12-weeks-of-age. Group D mice were used as a control, which were inoculated with sterile PBS. Groups A, B, and C showed significantly higher serum IgG and fecal IgA immune responses than those of the control group. After virulent challenge with a wild type A. pleuropneumoniae, the immunized groups A, B and C showed 33.3 %, 13.3 % and 26.7 % mortality as the control group showed 60 % mortality. These results showed that the protection against porcine pleuropneumonia using the construct can be optimized by a double intranasal vaccination.

Blood values of captive beira antelope (Dorcatragus megalotis) prior to and during an outbreak of fibrinous pleuropneumonia syndrome (FPPS).

Currently the only captive population of beira antelope (Dorcatragus megalotis) is held at the Al Wabra Wildlife Preservation, Qatar. An outbreak of a severe respiratory disease--fibrinous pleuropneumonia syndrome, most likely caused by Mycoplasma ovipneumoniae--led to a marked population decline. Reactive systemic inflammatory (AA) amyloidosis was noted as a chronic manifestation of the disease. Blood samples had been collected for biochemistry and hematology baseline values prior to the outbreak. Population-level changes were analyzed before and during the course of the outbreak in selected blood parameters (white blood cells [WBC], blood urea nitrogen [BUN], and creatinine). The annual population WBC increased and decreased concurrently with the population size, with a significant correlation between the two measures (R = 0.92; P = 0.001). Both BUN and creatinine values were higher during the outbreak. These values peaked at the same time as mortality, which was 1 yr after the WBC peak. These changes were interpreted as the transition from an acute disease with a primary respiratory manifestation into a chronic condition where renal amyloidosis led to chronic renal failure and death. Also, elevated liver values in diseased animals were attributed to amyloidosis. Parallels to a literature report on a lung disease complex caused by M. ovipneumoniae in bighorn sheep (Ovis canadensis) were found. Trends in population-level blood values of the beira antelopes implicate amyloidosis as a significant, long-term consequence of the putative Mycoplasma infection.

Invasive group A streptococcal infections in adults, France (2006-2010).

Severe invasive group A streptococcal diseases have re-emerged during the past 10-20 years. In order to provide a better insight into the current epidemiological situation in France, we analysed the questionnaires regarding all invasive strains received at the National Reference Center for Streptococci (CNR-Strep) between 2006 and 2010 from patients aged ≥ 18 and characterized them by emm typing, spe gene detection and antibiotic resistance. Among the 1542 invasive GAS strains studied, 78% (n=1206) were from blood cultures, and a streptococcal toxic shock syndrome (STSS) was described in 22% (n=340) of cases, mainly associated with necrotizing fasciitis (NF) and pleuro-pulmonary infections (p<0.001). The in-hospital fatality rate was 15%. A total of 83 different emm types were recovered but the three predominant emm types, representing almost 60% of the isolates, were emm1 (24%), emm28 (17%) and emm89 (15%). The preponderance of each emm type varied according to the year, with a significant constant increase of emm28 strains, whereas emm1 strains, representing approximately 32% of GAS invasive isolates in 2007 and 2008, dropped to <15% in 2010 (p<0.001). The distribution of phage-associated superantigen genes (speA, speC and ssa) was linked to certain emm types. Between 2006 and 2010, the percentage that was macrolide-resistant decreased from 11% to 5%, confirming the trend observed in 2007. Fortunately, emm1 strains associated with the most life-threatening clinical manifestations remain susceptible to all anti-streptococcal antibiotics.

Construction and characterization of a live, attenuated apxIICA inactivation mutant of Actinobacillus pleuropneumoniae lacking a drug resistance marker.

The apxIIC gene of Actinobacillus pleuropneumoniae serotype 7 was inactivated by homologous recombination using a sucrose counter-selectable marker system, resulting in a mutant strain that had no antibiotic resistance marker and expressed an inactivated ApxII toxin. The safety and immunogenicity of the mutant were evaluated in mice. The mutant strain caused no adverse effects in mice at doses up to 2 x 10(9) CFU via the intraperitoneal route while the parental strain induced total mortality at a dose of 2 x 10(7) CFU. Mice vaccinated intraperitoneally with the mutant strain had 100% and 70% protection against homologous (serotype 7) or heterologous (serotype 1, 3) challenge with A. pleuropneumoniae, respectively. The A. pleuropneumoniae mutant strain HB04C- and the counterselection method used in the study show promise in developing effective live vaccines for porcine pleuropneumonia and for other infections diseases of the respiratory system.

Protective efficacy of conjugate vaccines against experimental challenge with porcine Actinobacillus pleuropneumoniae.

In an attempt to protect pigs against swine pleuropneumonia induced by Actinobacillus pleuropneumoniae (SPAP) by neutralizing the effects of three virulence factors of A. pleuropneumoniae--the capsular polysaccharide (CP), the lipopolysaccharide (LPS), and the hemolysin protein (HP)--two subunit conjugate vaccines were prepared by covalently coupling the CP to the HP and the LPS to the HP. The CP, LPS, and HP were isolated from A. pleuropneumoniae, strain 4074, serotype 1, and the protective efficacy of the conjugate vaccines in swine experimentally infected with A. pleuropneumoniae was evaluated. Following a booster vaccination, a significant (P < 0.05) IgG antibody response to the CP, LPS, and HP was detected in the vaccinated pigs. The pigs vaccinated with the CP-HP and LPS-HP conjugates exhibited significantly less mortality (P < 0.05) and significantly greater weight gain (P < 0.001) than unvaccinated pigs. Vaccinated pigs exhibited significantly fewer and less extensive gross pulmonary lesions (P < 0.001) when compared with unvaccinated pigs. Thus, on the basis of mortality, weight gains, and pulmonary lesion formation, the two conjugate vaccines used in conjunction with one another provide noticeable protective efficacy against SPAP.

Epidemiology of Haemophilus pleuropneumoniae infection in pigs: a survey of Ontario Pork Producers, 1981.

Information about factors associated with the spread and the effect of pleuropneumonia was obtained from 418 pork producers in Ontario, who returned a mailed questionnaire. The overall herd prevalence of pleuropneumonia was 23.2%. The prevalence among herds with feeder pigs only was 34.3% and 16% among sow herds. The chance of pleuropneumonia breaking out in a herd was increased with increased traffic of pigs into the herd. The source of supplementary stock had an important effect on the chance of pleuropneumonia occurring. The highest risk resulted from introducing stock from salesbarns and the lowest from stock of health status known to the purchaser and supplied by one breeder only. Mortality, primarily among feeder pigs, and unthriftiness were the major effects of Haemophilus pleuropneumoniae infection. Stress, such as crowding or inclement climatic conditions, was associated with outbreaks of pleuropneumonia. This would suggest that the infection with H. pleuropneumoniae can be subclinical until stress precipitates the disease.