Granulomatous lesions caused by Pseudomonas aeruginosa in the ostrich (Struthio camelus)

Incidental Mycobacterium-induced granulomatous inflammation of the follicular pharyngeal tonsils in a South African farmed ostrich (Struthio camelus)

Avian mycobacteriosis (AM) is a zoonotic disease caused by Mycobacterium aviumcomplex (MAC), which can spread from avians to other farmed animals such as cattle and pigs as well as to humans. This study is the first report of granulomatous inflammation, as a result of avian mycobacteriosis, in the follicular pharyngeal tonsils of a farmed ostrich. The head of an apparently healthy farmed adult ostrich was obtained after slaughter. Each pharyngeal fold displayed a large tissue mass. This tissue was routinely prepared for light microscopy and stained with haematoxylin and eosin, periodic acid Schiff, Grocott methenamine silver, Gram and Ziehl-Neelsen. Immunohistochemistry (IHC) and polymerase chain reaction (PCR) were performed to identify Mycobacterium spp. and Mycobacterium tuberculosis complex, respectively. Histologically, the tissue masses consisted of confluent mature micro-granulomata that were characterised by central caseous necrosis surrounded by multinucleated giant cells, macrophages and lymphoid cells and an outer mature fibrous connective tissue capsule. Within some foci of caseous necrosis were variably sized colonies of small, Gram-negative, acid-fast bacilli, which showed positive IHC labelling for Mycobacterium spp., leading to a presumptive diagnosis of AM. PCR thus proved useful in excluding the presence of notifiable Mycobacteriumspp. The significance and role of the pharyngeal tonsils of ratites in diseases such as AM warrant specific attention. Moreover, as ratites are known to present with AM infections with apparently no visible loss in body condition, as presumably occurred in the present case, it is imperative that unusual masses in apparently healthy ratites be thoroughly investigated.

Granulomatous inflammation of salt glands in ducklings (Anas platyrhynchos) associated with intralesional Gram-negative bacteria

The "nasal glands" occur in many bird species and are powerful sodium ion-excretory organs. In ducks, they are located in supraorbital bony recesses. Granulomatous inflammation of these glands occurs with an incidence of approximately 1% in ducklings (Anas platyrhynchos), and is not associated with specific clinical symptoms. We investigated nine glands of eight animals with granulomas by gross pathology and histopathology, and compared results of bacteriology with 20 non-lesioned nasal glands. Adenitis was characterized by multifocal to coalescent heterophilic granulomas with central necrotic heterophils, and multinucleate giant cells, lymphocytes and plasma cells. Within the centres of the granulomas, there were clusters of Gram-negative bacteria that were identified as halo-tolerant Pseudomonas aeruginosa, Proteus mirabilis and Aeromonas hydrophila. Normal glands contained exclusively various halo-tolerant Gram-positive bacteria, mostly Streptococcus sp. and Enterococcus sp. The distribution of lesions and lack of clinical symptoms were suggestive of a localized ascending infection via the secretory ductules.

Killing of Pseudomonas pseudomallei by polymorphonuclear leukocytes and peritoneal macrophages from chicken, sheep, swine and rabbits

Differences in the kinetics of Pseudomonas pseudomallei killing by peritoneal macrophages (PM) and polymorphonuclear leucocytes (PMNL) from chickens, sheep, swine and rabbits were found. P. pseudomallei was rapidly killed by porcine PM and PMNL. However the bacterial killing by ovine and lapine PM and PMNL proceeded at a slower rate. In contrast, chicken PM and PMNL ingested and killed the lowest number of P. pseudomallei bacteria. The differences in the bactericidal activity of PM and PMNL from different animal species correlated with the level of their acid phosphatase and glycolytic activity.

Experimental melioidosis in hens

Experimental intramuscular infection of hens with Pseudomonas pseudomallei, strain 2796 (1 x 10(9) CFU from a 24-h culture) was reproduced. Clinical, paraclinical and pathomorphological findings were followed from 1 to 30 days after challenge. Haemagglutinin titre, bacterial dissemination in the viscera, number of leucocytes, alveolar (aMa) and peritoneal (pMa) macrophages and their phagocytic activity in vitro were studied. During the course of infection a leucocytosis as well as an increased haemagglutinin titre (1:256) were established. The number of bacteria per gram tissue in the spleen and liver was highest at 1 day post-infection (p.i.). Melioidose bacteria from egg yolk were isolated at 15 and 30 days p.i. Leucocyte and pMa phagocytic activity was maximal at 3 days p.i. unlike the activity of aMa which increased gradually until the end of the study. Inflammatory-necrotic changes were found in the viscera and brain at 3 and 15 days p.i. The investigation of experimental melioidosis infection in hens showed that they are susceptible to P. pseudomallei and this disease takes a generalized subacute course.