IN-VITRO INFLUENCE OF LISTERIA ON UTERINE ACTIVITY

In Austria the prevalence of listeriosis is 2.6 cases per million inha bitants yearly, hence rather rarely the cause of spontaneous abortion or premature birth. On the other hand, Listeria monocytogenes is found in 1% of the asymptomatic population as a component of stool flora. S ince the cause of premature labour contractions remains unclear in abo ut half of all cases, we examined 29 listeria strains for their abilit y to cause myometrial contraction by direct contact using an in-vitro uterine strip-model. Seven of nine L. monocytogenes strains were able to cause contractions; contractions were not inducible by an nonhaemol ytic mutane (SLCC 53, avirulent) nor by a rough strain (SLCC 5779, onl y slightly virulent). Three of six L. ivanovii isolates also exhibited the ability to induce contractions. None of the apathogenic species ( L. innocua, L. seeligeri, L. welshimeri, L. grayi and L. murrayl) was capable of activating contractions in our in-vitro model. Only L. mono cytogenes and L. ivanovii cause conjunctivitis after being dropped in rabbit's eyes (positive Anton Test). The influence of listeria on uter ine activity as found in our in-vitro model thus correlates with the c lassical pathogenicity test. We consider these in-vitro results as an additional argument to oppose the presence of L. monocytogenes in read y-to-eat foods.