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 Table of Contents  
CASE REPORT
Year : 2019  |  Volume : 21  |  Issue : 2  |  Page : 94-96

Mycotic aneurysm by non-typhoidal Salmonella


1 Department of Microbiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India
2 Department of Cardiovascular and Thoracic Surgery, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India

Date of Submission18-Oct-2019
Date of Decision02-Nov-2019
Date of Acceptance30-Nov-2019
Date of Web Publication17-Jan-2020

Correspondence Address:
Dr. Kavita Raja
Department of Microbiology, Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram - 695 011, Kerala
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jacm.jacm_27_19

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  Abstract 


Mycotic aneurysm is an arterial dilatation due to vessel damage caused by an infection. It encompasses primary infection of native artery resulting in aneurysm as well as an infection of pre-existing aneurysm. Mycotic aneurysm is a rare complication of salmonellosis and can be fatal if not diagnosed and treated at early stages. Here, we describe a rare case of abdominal aortic aneurysm caused by non- typhoidal Salmonella (Salmonella Enteritidis/Salmonella enterica serotype Enteritidis) which was successfully managed by a combination of surgical intervention and antibiotic therapy.

Keywords: Endoaneurysmorrhaphy, mycotic aneurysm, non-typhoidal Salmonella, Salmonella Enteritidis


How to cite this article:
Kaviyil JE, Pitchai S, Ponnambath DK, Raja K. Mycotic aneurysm by non-typhoidal Salmonella. J Acad Clin Microbiol 2019;21:94-6

How to cite this URL:
Kaviyil JE, Pitchai S, Ponnambath DK, Raja K. Mycotic aneurysm by non-typhoidal Salmonella. J Acad Clin Microbiol [serial online] 2019 [cited 2020 Feb 21];21:94-6. Available from: http://www.jacmjournal.org/text.asp?2019/21/2/94/276120




  Introduction Top


Mycotic aneurysm is a rare complication of infective endocarditis which develops rapidly and is associated with severe morbidity and mortality.[1] It is defined as an infectious disease of the wall of an artery with the formation of a blind, saccular outpouching that is contiguous with the arterial lumen.[2] Osler, in 1885, described a case of an aneurysm and coined the term 'mycotic aneurysm' to describe bacterial endocarditis-associated aneurysms.[3] Although called 'mycotic', the condition is not necessarily associated with fungal infection. Mycotic aneurysm of the aorta accounts for 0.7%–1.0% of all aortic aneurysms.[4] In Asia, however, reports suggest that the proportions of bacterial origin aneurysms are higher, Staphylococcus aureus being the most common causative agent, at about 13.3%.[1] Here, we report a case of an abdominal aortic aneurysm caused by non-typhoidal  Salmonella More Details and its management.


  Case Report Top


A 50-year-old male presented with lower abdominal pain for three months, with repeated episodes of intermittent fever with chills and rigors. The patient was conscious and oriented. He was a type II diabetic, hypertensive and had a history of chronic alcoholism. There was no history of intravenous (IV) drug abuse or syphilis. The fever was evaluated as for pyrexia of unknown origin. Laboratory investigations on admission showed an elevated serum C-reactive protein (32.39 mg/l). Urine routine investigation showed many pus cells but no bacteria on Gram's staining and was put up for culture. Serological tests for HIV, hepatitis B virus and hepatitis C virus were negative.

Computed tomography (CT) abdomen showed a saccular juxtarenal aneurysm with surrounding collection in the paravertebral space. Positron emission tomography scan done elsewhere revealed an intense fluorodeoxyglucose uptake surrounding the aneurysm eroding the lumbar vertebra, renal pelvis and pararenal spaces indicating inflammation or infection. On day two, the patient underwent a CT-guided aspiration for the pararenal fluid collection, which was sent for bacterial culture and cartridge-based nucleic acid amplification test (CBNAAT) for mycobacterial DNA. The Gram's staining of the fluid revealed many pus cells but no bacteria. The fluid sample showed no growth, and CBNAAT was negative for Mycobacterium tuberculosis.

Urine culture on MacConkey agar showed significant bacteriuria (>105 CFU/ml) with pure growth of Gram-negative, non-lactose-fermenting colonies which were subsequently identified on the third day as Salmonella enterica ssp. enterica by Vitek 2 (bioMérieux, Inc., Durham, NC, USA). On biochemical testing, the organism was motile, indole negative, urease negative and citrate positive. The Triple sugar iron agar slant result was alkaline/acid with abundant hydrogen sulphide and gas production. Lysine and ornithine were decarboxylated, whereas arginine was not hydrolysed. The isolate was sensitive to ampicillin, chloramphenicol, cotrimoxazole, ciprofloxacin and ceftriaxone. On serotyping, it agglutinated with Poly O, Poly H, O9 antisera. On sending to the National Salmonella and  Escherichia More Details Centre, CRI, Kasauli, Himachal Pradesh, India, it was reported as  Salmonella enteritidis Scientific Name Search ((antigenic structure: 9,12:g, m).

Widal test showed a significant reading for the somatic antigen only (1:160). Paired sample of blood was sent for culture; however, only the anaerobic BacT/ALERT culture grew non-typhoidal Group D Salmonella with similar susceptibility pattern as the urine isolate.

The patient was then started on IV ceftriaxone 2 g once daily (for two weeks) along with oral ciprofloxacin 750 mg twice daily (for six weeks). The patient underwent surgical correction by endoaneurysmorrhaphy using autogenous femoral vein as a conduit [Figure 1]. Surgery showed heavily inflamed juxtarenal aorta with multiple small periaortic lymph nodes and lymphatics. The aortic wall at the level of renal ostia was relatively healthy, but there was posterior wall dehiscence just below that with exposed anterior longitudinal ligament and some clots in the suspected aneurysm sac. In the first week following surgery, he had high drain output (>200 ml) from both thigh drains which subsequently reduced and both drains were removed. The patient was afebrile and was discharged on the 17th day after admission. Oral ciprofloxacin was continued for a total of six weeks.
Figure 1: Post-operative computed tomography angiogram with three-dimensional reconstruction showing patent infrarenal graft (blue arrow)

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  Discussion Top


Our patient, a mechanic by profession, was a middle-aged hypertensive, diabetic and chronic alcoholic male with no history of recent diarrhoea. Although how the infection was acquired in this specific case is not clear, Salmonella infections are generally acquired through the gastrointestinal route, with subsequent bacteraemia. The present case could be no different. In the present case, the non-typhoidal Salmonella was first isolated in urine culture, which was primarily done to evaluate the cause of lower abdominal pain and to look for urinary tract infection. He had no clinical history of any surgical procedure being performed, and an iatrogenic cause can, therefore, be ruled out.

Review studies on the disease have found that middle-aged and elderly people, males and those with hypertension, diabetes and atherosclerosis were more susceptible to this disease.[1] It has been well established in literature that mycotic aneurysms result from one of the three mechanisms of development, namely contiguous spread from an adjacent infected focus, septic embolisation commonly seen secondary to bacterial endocarditis and haematogenous seeding of the arterial wall during bacteraemia from a distant focus.[5] Non-typhoidal Salmonella bacteraemia usually presents as mild gastrointestinal infection; however, risk factors such as vascular damage and alcoholism can lead to complications such as fatal septicaemia, indolent infections and focal infections of internal organs.[6] In 2001, Acheson and Hohmann noted that approximately 5% of individuals with gastrointestinal illness caused by non-typhoidal Salmonella develop bacteraemia. In addition, patients with underlying risk factors are more likely to acquire focal infections.[7] These bacteria are invasive enteric pathogens and have the capacity to invade the intestinal mucosa and reach the bloodstream, by crossing the epithelial barrier through the Peyer's patches, thus contributing to mucosal erosion.[8]

Mycotic aneurysm is a potentially fatal condition in the field of vascular surgery and requires rapid diagnosis and management for successful resolution.[9] The literature survey from 2007 to 2016 by Guo et al. observed that the mortality rates were 21.43% and 7.14% after open surgery and endovascular aneurysm repair intervention, respectively.[1] In 2018, we encountered a total of 65 aneurysm cases with 48 of those being aneurysm of the abdominal aorta. The present case was the only instance of mycotic aneurysm among these. The most common cause of a mycotic aneurysm reported worldwide are Staphylococcus aureus, followed by Salmonella.[1] Mycotic aneurysm is a rare complication of  Salmonellosis More Details and can be fatal if not diagnosed and treated at early stages. An earlier study by Kam et al. has reported that more than 53% of Salmonella-infected aneurysms ruptured, whereas a recent publication reported a lower incidence of 17.54%, still a significant statistic in the post-antibiotic era.[1],[10] On review of reported cases worldwide, in the past decade caused by Salmonella, the same authors found that the most common causative strains were Salmonella Enteritidis (31.5%), followed by Salmonella choleraesuis (22.8%), Salmonella dublin (7%), Salmonella typhimurium (5.3%), Salmonella typhi (3.5%), Salmonella paratyphi B (3.5%), Salmonella Newport (1.8%) and Salmonella gallinarum (1.8%). They also found that mycotic aneurysms caused by Salmonella were predominantly in the abdominal aorta and clinically presented a picture of bloodstream infection, with repeated fever and chills, as was the case with our patient. The study also reported that 51% of the patients showed symptoms of pain at the site of infection caused by the increased local vascular pressure.[1] Salmonella Enteritidis is the predominant cause of food-borne salmonellosis in humans, in part because this serotype has the unique ability to contaminate chicken eggs without causing discernible illness in the infected birds.

In the present case, we hypothesise that the aneurysm resulted due to haematogenous seeding of the bacteria into the pre-existing atherosclerotic plaque.

Successful mycotic aneurysm management involves the elimination of the infection and reestablishment of arterial flow. The antibiotic treatment courses described in existing literature varied considerably. There is no consensus on the optimal duration of the antibiotic course.[11] Our patient was managed with a six-week course of oral ciprofloxacin and two weeks of ceftriaxone. On review, four weeks after cessation of antibiotics, the patient was asymptomatic.

Surgical approaches for resolution of mycotic aneurysms include extensive debridement of infected tissues, in situ reconstructions, extra-anatomic bypass in severe cases of infection and endovascular stent repair in case of medically fragile patients.[11]

In conclusion, Salmonella aneurysm remains a serious condition with high morbidity and mortality rates among people with underlying conditions that put them in the risk group. Early diagnosis and management are paramount for recovery. Appropriate antibiotic therapy for the right duration, in combination with surgical intervention, is necessary for the successful treatment of mycotic aneurysms.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
  References Top

1.
Guo Y, Bai Y, Yang C, Wang P, Gu L. Mycotic aneurysm due to Salmonella species: Clinical experiences and review of the literature. Braz J Med Biol Res 2018;51:e6864.  Back to cited text no. 1
    
2.
Kaufman SL, White RI Jr., Harrington DP, Barth KH, Siegelman SS. Protean manifestations of mycotic aneurysms. AJR Am J Roentgenol 1978;131:1019-25.  Back to cited text no. 2
    
3.
Kim YW. Infected aneurysm: current management. Ann Vasc Dis 2010;3:7-15.  Back to cited text no. 3
    
4.
Hsu RB, Chen RJ, Wang SS, Chu SH. Infected aortic aneurysms: clinical outcome and risk factor analysis. J Vasc Surg 2004;40:30-5.  Back to cited text no. 4
    
5.
Mitrev ZK, Anguseva TN. Life-threatening surgery for mycotic aneurysm. Aorta (Stamford) 2013;1:193-7.  Back to cited text no. 5
    
6.
Ryu CB, Lee M, Namgoong EK, Kee SY, Lee WG, Woo JH. Bacteremia with non-Typhi Salmonella and therapeutic implication. Kor J Intern Med 1995;10:146-9.  Back to cited text no. 6
    
7.
Acheson D, Hohmann EL. Nontyphoidal salmonellosis. Clin Infect Dis 2001;32:263-69.  Back to cited text no. 7
    
8.
Monack DM, Hersh D, Ghori N, Bouley D, Zychlinsky A, Falkow S. Salmonella exploits caspase-1 to colonize Peyer's patches in a murine typhoid model. J Exp Med 2000;192:249-58.  Back to cited text no. 8
    
9.
Miller DV, Oderich GS, Aubry MC, Panneton JM, Edwards WD. Surgical pathology of infected aneurysms of the descending thoracic and abdominal aorta: Clinicopathologic correlations in 29 cases (1976 to 1999). Hum Pathol 2004;35:1112-20.  Back to cited text no. 9
    
10.
Kam MH, Toh LK, Tan SG, Wong D, Chia KH. A case report of endovascular stenting in Salmonella mycotic aneurysm: a successful procedure in an immunocompromised patient. Ann Acad Med Singapore 2007;36:1028-31.  Back to cited text no. 10
    
11.
Aoki C, Fukuda W, Kondo N, Minakawa M, Taniguchi S, Daitoku K, et al. Surgical management of mycotic aortic aneurysms. Ann Vasc Dis 2017;10:29-35.  Back to cited text no. 11
    


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