Listeria isolations from feces of patients with diarrhea and from healthy food handlers.

A study was undertaken on the presence and frequency of Listeria sp. in feces from 1,000 patients suffering from diarrheal diseases and from 2,000 healthy persons. Furthermore, the feces of patients were examined for other well-documented enteropathogens such as Campylobacter, Salmonella, Shigella, Staphylococcus aureus, Yersinia enterocolitica, protozoa and rotavirus as well as for organisms of questionable enteropathogenic potency such as fungi, i.e. Candida. Finally, in continuation of previously described investigations of the enteropathogenic role of Proteus mirabilis but not of Proteus vulgaris, both these species were studied too. Only Listeria innocua and Listeria monocytogenes could be detected in the investigated fecal specimens. There were no differences of the frequencies of L. innocua, and L. monocytogenes between patients and healthy persons. 17 strains (= 1.7%) of L. innocua and six strains (= 0.6%) of L. monocytogenes were isolated from 1,000 samples of patients. As a comparison 2,000 fecal samples from healthy people contained 40 strains (= 2.0%) of L. innocua and 16 strains (= 0.8%) of L. monocytogenes. A coincidence study showed that there were no statistically significant correlations between well-known enteropathogens and Listeria sp., Proteus sp. or any of the other isolates. Significant correlations were found only between harmless species such as L. innocua and P. vulgaris.