Porcine haemophili and actinobacilli: characterization by means of API test strips and possible taxonomic implications

Abstract

Thirty Haemophilus strains and six Actinobacillus strains, all of porcine origin, were examined for their biochemical reactivity on API 20E and API ZYM test strips using dense cell suspensions (supplemented with NAD as appropriate) as strip inocula. When combined with a test for V-factor dependency, the use of both strips allowed adequate differentiation of closely related organisms. Numerical taxonomic analysis of the data demonstrated that the majority of the haemophili and actinobacilli studied could be placed in one of four major clusters; these clusters contained, respectively, the H. pleuropneumoniae--A. pleuropneumoniae strains, the H. parasuis strains, strains belonging to Haemophilus taxon "minor group," and strains belonging to an unusual group of mannitol-positive, urease-negative haemophili. A representative of Haemophilus species taxon C and an unusual Actinobacillus isolate appeared to be comparatively unrelated to organisms in the four major clusters. Although it may, on occasion, be difficult to place an unusual isolate in any one particular group, owing to the uncertain taxonomy of some of these organisms, it is concluded that API test strips can serve as useful tools for the characterization and differentiation of porcine haemophili and actinobacilli.

Actinobacillus suis strains isolated from healthy and diseased swine are clonal and carry apxICABDvar. suis and apxIICAvar. suis toxin genes

“…The cumulative results of the biochemical testing of the isolates are presented in Table 3. The results obtained with the Sensititre system were comparable to those obtained by more traditional test methods, as reported previously (4,9,23,27,32). The biotypes of the A. suis isolates from healthy animals were virtually identical to those of clinical isolates, with the exception of esculin hydrolysis and the ability to produce acid from xylose.…”

“…In the diagnostic laboratory, A. suis isolates may be identified on the basis of their hemolytic phenotype and their ability to grow on MacConkey agar; hydrolyze esculin; produce catalase, oxidase, and urease; and produce acid from arabinose, cellobiose, dextrose, lactose, melibiose, salicin, sucrose, and trehalose but not from mannitol or sorbitol (4,9,23,27,32). To date, no attempt has been made to serotype A. suis, and it is known that A. suis possesses some cross-reactive antigens including enterobacterial common antigen (6), outer membrane proteins (19), somatic antigens (29,31), and exotoxins (7,8,16).…”

Immunohistochemical Detection ofHaemophilus ParasuisSerovar 5 in Formalin-Fixed, Paraffin-Embedded Tissues of Experimentally Infected Swine

“…7,19 Cross-reactivity could be due to the close relationship of these bacteria. 11,16 In a numerical taxonomic analysis (based on the biochemical reactivity on API20E and API ZYM test strips) using dendrograms that compared the similarity of H. parasuis, A. pleuropneumoniae, Pasteurella multocida, and Bordetella bronchiseptica, a similarity of 86% between H. parasuis and A. pleuropneumoniae was found, but in some cases comparing specific strains of these bacteria similarity reached 91% and 93%. 11 However, cross-reactivity could be relatively serovar specific.…”

“…11,16 In a numerical taxonomic analysis (based on the biochemical reactivity on API20E and API ZYM test strips) using dendrograms that compared the similarity of H. parasuis, A. pleuropneumoniae, Pasteurella multocida, and Bordetella bronchiseptica, a similarity of 86% between H. parasuis and A. pleuropneumoniae was found, but in some cases comparing specific strains of these bacteria similarity reached 91% and 93%. 11 However, cross-reactivity could be relatively serovar specific. In the study in which cross-reactivity was not found, only A. pleuropneumoniae serovar 1 was tested, and the existence of cross-reactivity among tested H. parasuis serovars was not investigated.…”

Characterization of Haemophilus spp. isolated from healthy swine and evaluation of cross-reactivity of complement-fixing antibodies to Haemophilus pleuropneumoniae and Haemophilus taxon "minor group"

“…The 10 urease-negative isolates were indole positive and exhibited a pattern of carbohydrate fermentation which distinguished them from H. parasuis and Haemophilus taxon C. Differences exist in reported biochemical activity of swine haemophili (2,6,7,12,20,23). Although these varying TABLE 4.…”