SERRATIA FICARIA - A MISIDENTIFIED OR UNIDENTIFIED RARE CAUSE OF HUMAN INFECTIONS IN FIG TREE CULTURE ZONES

Serratia ficaria, an enterobacterium involved in the fig tree ecosyste m, has been isolated from human clinical samples in rare instances, an d its role as a pathogen is unclear. In 7 years, we have isolated S. f icaria from seven patients; it was the only pathogen in 4 patients, in cluding a patient with septicemia described previously and three patie nts with gallbladder empyemas described in the present report, From Ma rch 1995 to July 1997, the incidence of biliary infections due to S. f icaria was 0.7%, We discuss the digestive carriage of this bacterium a nd its epidemiology with respect to the fig tree life cycle. Since fig trees grow around the Mediterranean as well as in the United States ( California, Louisiana, Hawaii), S. ficaria should be more frequently i solated. In our experience, various strains have been misidentified or unidentified by commercial systems. Incorrect identification could be an additional explanation for the paucity of reported cases. S, ficar ia produces nonpigmented, lactose-negative colonies which give off a p otatolike odor, This odor is the primary feature of S, ficaria and mus t prompt reexamination of the identifications proposed by commercial s ystems. We tested 42 novel strains using three commercial systems: Vit ek gram-negative identification (GNI) cards and API 20E and ID 32E str ips (bioMerieux, Marcy-l'Etoile, France). The percentages of positivit y that we have obtained were lower than those published previously for the following characteristics: lipase, gelatinase, DNase, and rhamnos e. The best system for the recognition of S. ficaria is ID 32E, which correctly identified 27 of 42 strains. The API 20E system gave correct identifications for only two Strains. S. ficaria was not present in t he Vitek GNI card system database.