Nachweis von Salmonella spp. bei Landschildkröten

In the present study an efficient procedure for detecting
salmonellas in feces of tortoises should be established. First of
all a survey of occurrence of salmonellas in reptiles and their
importance for reptiles as well as for man is given. Next an
appropriate incubation temperature for multiplying salmonellas of
reptilian origin in a selective enrichment medium was evaluated.
Furthermore 86 salmonella strains isolated from reptiles were
tested on nine different selec-tive solid media for their
appearance; these media were BPLS-, DCLS-, HE-, MLCB-, ÖNÖZ-,
RAMBACH-, SS-, WS- and XLD-Agar. The media were reviewed according
to their qualification in identifying those strains. Finally 167
fecal samples of tortoises of different species and two lizards
from Munich area were examined according to the former established
procedure whether or not they harboured salmonellas. Therewith the
suitability of this method should be determined and the incidence
of salmonellas of these tortoises should be investigated. Following
results were obtained: The best growth of salmonellas resulted from
RAPPAPORT-VASSILIADIS and selenite cystine enrichment broth at an
incubation temperature of 35-37 °C. The higher critical temperature
for incubation of RAPPAPORT-VASSILIADIS enrichment medium is 42 °C;
especially Salmonella subspecies IIIb often are inhibited in this
medium at this temperature. For isolating salmonellae as well as
for inhibiting competing organisms, an incubation temperature of 41
°C is emphasized for enrichment in RAPPAPORT-VASSILIADIS broth.
Neither temperature investigated had any inhibitory effect on the
growth rate of salmonellas in selenite cystine medium, but its
inhibitory activity on competing organisms proved strik-ingly less,
too. RAPPAPORT´s enrichment medium supports growing of salmonellas
of reptilian origin least of all. For isolation of salmonellas from
tortoises BPLS- and XLD-agar proved best for direct strik-ing as
well as after previous enrichment in either RAPPAPORT-VASSILIADIS
or selenite cystine medium or both. For investigation of snakes and
lizards MLCB- or eventually WS-agar should be used. For achieving a
most reliable statement at least two different agar media should be
used for direct plating as well as for enrichment subculture.
RAPPAPORT-VASSILIADIS and se-lenite cystine enrichment medium
should be used simultaneously and spread on at least twice at
different times of incubation. On account of the intermittent
excretion of salmonellas sev-eral fecal samples should be examined.
The more extended the effort the better the results will be. Though
a single negative result never is absolutely reliable. In this
study the incidence of salmonellas in tortoises – investigating
only a single sample from each animal – ranks at about 10 %. Two
out of 18 tortoises positive for salmonellas originated from
different private owners; the remaining 16 belonged to two stocks
of a pet shop. Therefore statements about higher incidence of wild
cut or home bred tortoises were not practicable.