abdominal aortic aneurysms ( aaa ) can be repaired with an aortic bifemoral bypass graft , which is considered an ideal procedure for aortic aneurysms , aorto - iliac disease or aortic atherosclerosis .
though rare , infections involving the graft can happen , typically , two to five years following implantation .
anaerobic , non - sporulating , gram - positive bacilli from the normal human gut flora can occasionally be implicated in invasive diseases .
notably , eggerthella lenta , formerly known as eubacterium lentum , often causes clinically significant bacteremia with a significant mortality rate .
herein we report a case of an aortobifemoral bypass graft with an aortoenteric fistula , giving rise to a very rare bacteremia caused by the species eggerthella lenta .
a 75-year - old male with a past medical history significant for type 2diabetes mellitus , hypertension , chronic thrombocytopenia and chronic kidney injury underwent resection of a ruptured aaa and placement of an aortobifemoral bypass graft .
his postoperative course was eventful for renal failure , which required four cycles of dialysis with improvement .
twenty - nine months later , the patient was seen in the emergency department with a two - day history of rigors , dysuria , polyuria and burning micturition complicated by fever , weakness and lethargy observed by his family on the day of admission .
blood pressure upon examination was 70/35 mmhg , rising to 90/48 mmhg after a fluid bolus ; temperature was 101 degrees fahrenheit ; heart rate 90/min ; and respiratory rate was 20/min .
blood work was significant for a white blood cell count of 18,000 ; lactic acid of 4.1 , 20 percent bands and platelet count of 20,000.urinalysis was remarkable for white blood cells , red blood cells and moderate leukocyte esterase .
physical examination revealed diffuse abdominal tenderness , and peri - umbilical tenderness with deep palpation without peritoneal signs.the patient was admitted to the intensive care unit with a diagnosis of severe sepsis secondary to urinary tract infection with high anion gap metabolic acidosis secondary to lactic acidosis .
blood cultures and urine cultures were drawn , which demonstrated eggerthella lenta septicemia and escherichia coli extended spectrum beta - lactamase ( esbl)-positive urinary tract infection .
a subsequent abdominal computed tomography ( ct ) with contrast demonstrated induration with inflammatory changes around the aortobifemoral bypass graft .
furthermore , the graft showed stranding around the aorta near the iliac components with presence of an air bubble between these components [ figure 1 ] .
this finding raised the possibility of gas producing infection or an aortoenteric fistula communicating with an adjacent loop of bowel , either of which could have feasibly contributed to the aortic graft harboring eggerthella lenta .
the patient was recommended to have graft replacement surgery with repair of the fistula in order to remove the source of infection ; however , he refused , preferring to be treated with iv antibiotics instead , despite the considerable risk . repeated blood cultures after treatment with antibiotics were negative and the patient was discharged home on antibiotics as an outpatient with the possibility of requiring chronic suppression with antibiotics .
ct scan of the abdomen and pelvis showing an induration with inflammatory changes around the aorto - iliac graft and an small air bubble ( yellow arrow ) between the two legs of the graft , possibly caused by a fistulous communication with the bowel
aortoenteric fistulas can involve any part of the small or large bowel , but it is more common to find them in the third and fourth portions of the duodenum .
mucosal bleeding can be one of the signs as erosions of the graft into the intestines can precede massive gastrointestinal bleeding from an established aortoenteric fistula .
staphylococcus aureus and gram - negative bacilli , accompanied by fever , signs of infection and leukocytosis , typically cause early infections ( less than four months after repair ) .
the presentation of late - onset infections can be subtle without any specific signs or symptoms with an absence of fever being common .
in fact , in few studies , the absence of fever and stay in the intensive care unit ( icu ) , was associated with an increased risk of mortality .
they can also present with complications of the graft infection , such as a pseudoaneursym , sepsis or bleeding .
our patient did have fever , leukocytosis and hypotension , but thiscould have been caused by his concurrent urinary tract infection with e. coli .
it is possible that had this patient not had symptoms from his urinary tract infection , his bacteremia may have been missed .
the use of graft devices for repair of an aaamay require a complex , open - air procedure with exposure of the compromised vessel .
this , of course , increases the risk of an infectionfrom the device as well as the wound .
the incidence of aaa graft infection is low ( 0.4% to 3% ) , with one - third of those infections manifesting as aortoenteric erosions / fistula .
the management of an aortoenteric fistula has typically required replacement of the affected graft and repair of the fistulae , a surgery with a mortality risk of 20 to 30 percent .
bacteremia associated with the aortoenteric fistula has also been reported to have a high mortality risk . in our case ,
the ct scan of the patient raised the possibility of an aortoenteric fistula that was likely to be the source of the patient 's infection with eggerthella lenta . after being explained the risk of the surgery , as well as the possibility of not being able to resolve the infection without surgery , the patient declined to move forward with the procedure .
although lactobacillus , clostridium and propionibacterium species are more commonly encountered , many other lesser known anaerobic gram - positive bacilli can be involved in clinical infections as well .
members of this genus are anaerobic , non - sporulating , non - motile , gram - positive bacilli that grow singly , as pairs or in short chains . classification and identification of this bacterium
is reliably achieved through specialized cultured blood samples identifying the gram - positive bacilli as eggerthella lenta with 94% and 99% probability and confirmed by 16srna pcr gene sequencing .
eggerthella lenta can be found in many different parts of the body , most commonly in the colon and feces .
bacteremia associated with this bacterium carries a high mortality rate ( 20 - 40% ) especially if it is found to be the only pathogen in the blood .
eggerthella lenta has been linked with many conditions such as ulcerative colitis , crohn 's disease , sinusitis , abscesses , pelvic inflammatory disease , malignancy and pancreatic abscesses among others .
nearly all infections with anaerobic bacteria originate from the patient 's own microflora ; therefore , we can conclude that this patient 's bacteremia was from his own flora , with the likely source to be the aortoenteric fistula . due to the fastidious nature of these organisms
, it can be exceedingly difficult to isolate these anaerobes from the site of an infection and easy to miss .
isolating them requires the appropriate method of collection , transportation and cultivation of specimens , which requires a laboratory capable of performing 16s rrna gene analysis .
, it took three days in order to get a positive blood culture and another three days to identify the organism and get antibiotic susceptibility .
treatment with etrapenem proved to be successful as repeat cultures were negative . though bacteremia caused by eggerthella lenta is rare , if it is present , it is almost always clinically significant and requires prompt diagnosis and treatment .
we believe that patients , who have had repair of an aaa and present with abdominal pain with or without fever , should have their blood appropriately cultured for anaerobic bacteria .
it should be noted that patients who undergo this procedure are recommended to have yearly ct scans performedto rule out infections or fistulas that can lead to dangerous bacteremia .
 the presence of an aortoenteric fistula following aortobifemoral graft repair of an abdominal aortic aneurysm is associated with a high probability of infection leading to clinically significant bacteremia . 
 we report a case of an aortoenteric fistula that developed two years after initial aortic grafting resulting in colonization with the anaerobe , eggerthella lenta . 
 this dangerous bacterium is difficult to culture , associated with high mortality and the patient may have mild symptoms on presentation . 
INTRODUCTION
CASE REPORT
DISCUSSION
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