Unusual pathogens – Case reports of 4 rare findings

Traditionally, bacteriological diagnostics are based upon colony-morphology and biotyping. During the later years, MALDI-TOF-identification has broadened the spectrum of bacteria that can be identified in laboratory submissions. Four case-stories on potentially important pathogens are presented.

Case 1: Massive problems with arthritis around weaning. 4 piglets were examined. Deeply cut teeth and swollen joints with fibrinous/purulent arthritis were observed. Four joints per piglet were examined bacteriologically.

Case 2: Many cases of arthritis during the first week of life. 3 piglets were examined (submitted with a time period of 14 days in between). Deep wounds on fore-knees, wound-infection after castration and fibrinous arthritis (2 of 3 piglets) were observed. Four joints per piglets were examined bacteriologically.

Case 3: Abortions one week before expected farrowing. 7 foetuses (from one abortion) were examined. Compact consistency of lungs and enlarged livers were observed. Lung-tissue from 3 foetuses was examined bacteriologically.

Case 4: Sudden deaths in growing pigs. One pig (20 kg) was examined. Valvular endocarditis was observed and heart-valves were examined bacteriologically.

Bacteriological examinations were carried out aerobically on meat-juice agars (In House (ox-heart, Peptone P (Oxoid), NaCL, Agar (Oxoid)).

Case 1: In 8 joints (1-3 per piglet) moderate to massive growth of greyish, shiny colonies (1-3 mm in diameter) was observed in pure culture after 24 hours. MALDI-TOF identified the bacteria as Actinobacillus equuli.

Case 2: In 3 joints (0-2 per piglet) single colonies/ moderate growth of small alfa-haemolytic colonies were seen in a mixed flora after 24 hours. MALDI-TOF identified isolates from both laboratory submissions as Aerococcus viridans.

Case 3: In 2 of 3 lungs, massive growth of pinpoint, haemolytic colonies was observed in pure culture after 48 hours. MALDI-TOF identified the bacteria as Trueperella abortisuis.

Case 4: Pinpoint colonies were detected in a mixed flora after 24 hours. MALDI-TOF identified the bacteria as Streptococcus gallolyticus (previously: Streptococcus bovis biotype 1).

Traditionally, none of the presented bacteriae are considered important pathogens in pigs. Our findings indicate that they may be relevant to take into consideration. Actinobacillus equuli and Aerococcus viridans were previously isolated from arthritic joints in pigs and Trueperella abortisuis was previously isolated from aborted pig-fetuses and placenta. Streptococcus gallolyticus is seen in human endocarditis.

Disclosure of Interest: None Declared.