in january 2007 , a 55-year - old man was hospitalized in paris , france , with a 3-week history of nonbloody diarrhea , vomiting , dehydration , and low - grade fever . medical history included renal transplantation for chronic renal failure and chronic hepatitis c. immunosuppressive regimen included mycophenolate mofetil , tacrolimus , and prednisone . at the time of admission , his temperature was 37.8c and he had moderate and painless abdominal distension . laboratory values were 5.9  10/l leukocytes , 0.4  10/l lymphocytes , 9.7 g / dl hemoglobin , 137,000/ml platelets , 470 mol / l creatinine , and < 5 mg / l serum c - reactive protein . liver tests were within normal limits except -glutamyltranferase , which was increased ( 244 u / l ; reference < 50 u / l ) . blood cultures yielded coryneform gram - positive rods with intensely -hemolytic colonies ; catalase and esculin hydrolysis test results were positive , consistent with listeria spp . ( 1 ) . because listeriosis was suspected , intravenous amoxicillin and gentamicin therapy was initiated . semiquantitative aerobic fecal culture showed the same coryneform gram - positive rods ( 10 cfu / g ) . the api coryne biochemical test ( biomrieux , marcy ltoile , france ) identified blood and fecal isolates as listeria spp . the 3 isolates from blood and 1 from feces were referred to the french national reference centre for listeria ( institut pasteur , paris , france ) . they showed identical profiles by pulsed - field gel electrophoresis ( figure , panel a ) . susceptible to amoxicillin and gentamicin ; resistant to third - generation cephalosporins , clindamycin , and aztreonam ( 2 ) . contrary to l. monocytogenes , which is naturally resistant to fosfomycin in vitro ( 9 ) , all isolates were susceptible to fosfomycin in vitro , as previously reported ( 2 ) . a ) the 4 isolates , 07/00250 , 07/00251 , and 07/00252 from blood , and 07/00253 from feces , were analyzed by pulsed - field gel electrophoresis ( pfge ) with apai and smai restriction enzymes ( 9 ) . ivanovii type strain american type culture collection ( atcc ) 19119 was used as control . profiles were compared according to band positions by using the dice coefficient and were clustered by using unweighted pair  group method averages . specific virulence locus lipi-2 and its phenotypic marker ( sphingomyelinase production as shown by a camp - like test with an indicator strain of rhodococcus equi on sheep blood agar ) . arrowheads indicate positions of the oligonucleotide primers used in the 19 intragenic and intergenic pcrs to map the locus in the isolates ; arrows represent genes ( those belonging to lipi-2 are gray , the sphingomyelinase gene is black , and flanking genes from the core listerial genome are white ) ( 10 ) . right , typical shovel - shaped synergistic hemolysis reactions caused by l. ivanovii sphingomyelinase in the presence of r. equi cholesterol oxidase compared with the negative reaction given by l. monocytogenes ( lm ) . c ) invasion ( gentamicin protection ) assays in bovine ( madin - darby bovine kidney ) and human ( hela ) epithelial cells . the human isolates were compared with ruminant isolates atcc 19119 , pam 55 , and pam 19 and with the l. monocytogenes strain p14a . the isolates were compared with prototypic l. ivanovii strains from sheep ( american type culture collection 19119 type strain , ivan ivanov , 1955 , pam 19 , australia ) and goats ( pam 55 , spain ) . we determined the activation status of the virulence gene regulator prfa . for l. monocytogenes , the prfa - regulated factors are mainly expressed in vivo , but for l. ivanovii , they are constitutively overexpressed in vitro ( 2,11 ) . some of these virulence factors have easily detectable phenotypes , such as hemolysis on blood agar , plcb phospholipase activity on egg yolk agar , and hpt hexose phosphate transporter activity in acidification test ( 2,12 ) . all isolates were phenotypically identical ; they produced broad halos of hemolysis and lecithinase reactions and had positive glucose-1-phosphate acidification test results , reflecting the constitutive activation of the prfa virulence regulon . pcr mapping was used to test for l. ivanovii  specific pathogenicity island lipi-2 ( 13 ) . lipi-2 comprises 10 internalin genes and the sphingomyelinase gene smcl and is perfectly conserved within l. ivanovii , including the distantly related subspecies londoniensis ( 13 ) . the phenotypic marker for lipi-2 , smcl - encoded sphingomyelinase , was assessed by the synergistic hemolysis ( camp - like ) test ( 13 ) and was found in all strains ( figure , panel b ) . finally , we performed invasion assays with madin - darby bovine kidney ( mdbk ) cells and hela cells ( human ) . confirming previous observations ( 13 ) , all l. ivanovii strains were hyperinvasive in mdbk cells and less invasive in hela cells compared with l. monocytogenes ( figure , panel c ) . invasion assays expressing human e - cadherin or not did not show substantial differences , suggesting that l. ivanovii inla does not interact with e - cadherin , in contrast to l. monocytogenes inla ( 6 ) ( data not shown ) . the 4 patient isolates showed slightly lower invasion capacity in mdbk cells than did isolates from ruminants but were still hyperinvasive relative to l. monocytogenes . we found 3 other well - documented cases of l. ivanovii  associated human infection ( table ) 1 febrile diarrhea ( 7 ) and 2 bacteremia cases ( 8,10 ) . the infections were associated with aids , metastatic carcinoma , or substance abuse ; 2 patients were > 60 years of age . thus , as for l. monocytogenes ( 1 ) , human l. ivanovii infection is associated with immunodeficiency , underlying debilitating conditions , or advanced age . in at least 3 other instances , bacteria were found in human samples , 2 in fetoplacental tissue and lochia and 1 in a mesenteric lymph node ( 4,5 ) ( table ) . the pathologic changes associated with l. ivanovii in humans appear similar to those in ruminants , i.e. , fetoplacental infections and septicemia ( often accompanied by enteritis ) . typically , meningoencephalitis is not caused by l. ivanovii in ruminants , whereas it is a hallmark of l. monocytogenes infection in ruminants and humans ( 1 ) . lack of central nervous system involvement could be a general characteristic of l. ivanovii infection regardless of host species . the specific pathogenic features of l. ivanovii may be caused by sequence differences in virulence genes shared with l. monocytogenes or by differences in the gene content of these 2 species ( 1,6 ) . although the rare occurrence of l. ivanovii infections in humans ( 3 ) could result from lower pathogenicity for humans , it may reflect ecologic characteristics of the species . l. ivanovii is isolated only occasionally from animals or environmental sources ( 2,4,5 ) , suggesting a limited distribution in nature , including in food . therefore , the few human cases of l. ivanovii infection reported might correspond to what would be proportionally expected for a species with such sporadic occurrence . that gastroenteritis preceded bacteremia and that the same isolates were found in the feces strongly indicate a foodborne infection in the patient reported here and that l. ivanovii causes gastroenteritis in humans , as reported for l. monocytogenes ( 14 ) . days before onset of gastroenteritis , the patient had eaten artisanal goat cheese made from raw milk . unfortunately , no cheese sample was available for bacteriologic investigation . although the portal of entry of l. ivanovii has not been formally established , l. ivanovii infection in ruminants is associated with eating spoiled silage or hay , as happens with l. monocytogenes , suggesting foodborne origin . simultaneous detection of l. ivanovii in the feces and blood of a human , together with previous association between l. ivanovii and human mesenteric adenitis ( 5 ) , suggests that these bacteria can cross the intestinal barrier in humans , cause gastroenteritis , and disseminate into the bloodstream . although l. monocytogenes are by far the leading cause of human listeriosis , our report shows that l. ivanovii can also cause bacteremia in immunocompromised , debilitated patients .
two species of listeria are pathogenic ; l. monocytogenes infects humans and animals , and l. ivanovii has been considered to infect ruminants only . 
 we report l. ivanovii  associated gastroenteritis and bacteremia in a man . 
 this isolate was indistinguishable from prototypic ruminant strains . 
 l. ivanovii is thus an enteric opportunistic human pathogen .