[Detection of Actinobacillus equuli ssp. equuli in piglets with purulent polyarthritis and tendovaginitis]. / Nachweis von Actinobacillus equuli ssp. equuli bei Saugferkeln mit eitriger Polyarthritis und Tendovaginitis.

Actinobacillus equuli ssp. equuli is an opportunistic pathogen in horses, mainly known to cause "sleepy foal disease". In comparison to horses, there are only few reports describing diseases in pigs associated with this gram-negative bacterium. This case report describes an outbreak of infection in a combined farrow-to-finish-farm. In September 2018, the following symptoms were noticed in one third of all newborn piglets from gilts and sows: 6-8 hours after birth piglets became weak and developed swollen joints with moderate to severe lameness. The piglets exhibited lethargy, a subset were non-ambulatory. An elevated piglet mortality within the first days within birth was noted. Seven piglets that succumbed to the disease (days 2-3 of life) were submitted for examination, 4 of which underwent pathological examination. The main findings were purulent polyarthritis and tendovaginitis. In addition, purulent inflammation was detected in the brain and kidneys of one animal. In the bacteriological examination A. equuli ssp. equuli was isolated in a total of 18 samples (brain, joints, suppurative structures of limbs), in a subset of cases as pure culture. For identification, cultural and biochemical characteristics were tested and a mass spectrometry analysis (MALDI-TOF MS) was performed. Further laboratory testing included 16 S rRNA-gene sequencing, a PCR in order to examine for special apx toxin genes as well as a PCR differentiating the two subspecies of A. equuli. It was not possible to identify the source of infection and routes of spread within the pig herd. The bacterial isolates were used for the production of an autogenous vaccine.

Actinobacillus equuli ssp. haemolyticus in a semi-occlusively treated horse bite wound in a 2-year-old girl.

We report on the isolation of Actinobacillus equuli ssp. haemolyticus from wound smears of a 2-year-old girl who was admitted to the hospital due to partial amputation of the distal phalanx of her right middle finger caused by a horse bite. A. equuli typically causes diseases in horses and only very few reports describing human infections (mostly associated with wounds) are available in the literature. Interestingly, although the bacteria could be found in consecutive samples taken at different points in time, there were no signs of advancing infection or inflammation. Moreover, the fingertip regenerated after 74 days under semi-occlusive dressings with very pleasant results. For strain identification two automated systems were employed producing discrepant results: VITEK 2 described the pathogens as Pasteurella pneumotropica while MALDI-TOF MS analysis revealed A. equuli. Sequence analysis of 16S rDNA gene finally confirmed A. equuli ssp. haemolyticus as the isolated strain. The antimicrobial susceptibility testing was performed according to the CLSI criteria for Pasteurella spp. Additionally we conducted a test according to the EUCAST criteria.

Metritis, valvular endocarditis, and septicemia by Actinobacillus equuli in a gilt in the United States.

A 1-year-old pregnant Yorkshire gilt was found dead with no previous clinical signs. Gross findings included metritis, splenomegaly, and valvular endocarditis. Bacterial endocarditis (in the mitral and tricuspid valves) and metritis with dissemination to multiple organs was diagnosed by using histologic examination. Gram-negative coccobacillary organisms present in the valvular lesions were characterized as Actinobacillus equuli by using polymerase chain reaction examination on formalin-fixed, paraffin-embedded tissues (FFPE). A. equuli is rarely reported as a cause of septicemia in pigs in Europe. A. equuli in pigs in the United States has been reported only twice and not, to our knowledge, in the last 30 years. This is the first time that molecular techniques have been used to characterize this organism in FFPE porcine tissues.

An unusual Actinobacillus equuli strain isolated from a rabbit with Tyzzer's disease.

Actinobacillus equuli was isolated in pure culture from the liver and lungs of an adult rabbit with Tyzzer's disease (Clostridium piliforme). Based on the haemolytic features on blood agar plates, a positive reaction in the CAMP-test, hydrolysis of esculin, the inability to ferment l-arabinose, tDNA-PCR and sequencing of the 16S rRNA gene, the isolate was classified as A. equuli subsp. haemolyticus biovar 1. However, the aqxA gene, characteristic for haemolytic A. equuli strains, was not detected by PCR.

Actinobacillus equuli subsp. equuli associated with equine valvular endocarditis.

Microbiological and pathological data from a case of equine valvular endocarditis are reported. Limited information is available on the pathogenic potential of equine Actinobacillus species as several strains originate from apparently healthy horses. After the establishment of two subspecies within this species, this seems to be the first report of an etiological association between A. equuli subsp. equuli and equine endocarditis. Furthermore, new information on some phenotypical characteristics of this subspecies is reported, compared to previous findings.