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Mini Review - (2022) Volume 10, Issue 4

Mycotic Aneurysms Caused by Pasteurella and Capnocytophaga Species
Ali Etemady-Deylamy and Getahun Abate*
Department of Internal Medicine, Division of Infectious Diseases, Saint Louis University 1100 S Grand Blvd, DRC 8th Floor, Saint Louis, USA
*Correspondence: Getahun Abate, Department of Internal Medicine, Division of Infectious Diseases, Saint Louis University 1100 S Grand Blvd, DRC 8th Floor, Saint Louis, USA, Tel: +1314-977-9044, Email:

Received: 07-May-2022, Manuscript No. JVMS-22-16500; Editor assigned: 10-May-2022, Pre QC No. JVMS-22-16500(PQ); Reviewed: 24-May-2022, QC No. JVMS-22-16500; Revised: 31-May-2022, Manuscript No. JVMS-22-16500(R); Published: 08-Jun-2022, DOI: 10.35248/2329-6925.22.10.453


Infected aneurysms are rare and present with vague symptoms or more severe symptoms at time of sepsis and/or rupture which is associated with significant mortality. Even rarer is presentation with an opportunistic infection from domesticated pets; however, risk factors are well described. Given the fastidious nature of these organisms, a detailed exposure history is important as well as consideration for additional serologic work up. Here, we discuss the epidemiology, diagnosis, and management of common infections from cats and dogs.


Vasculitis; Mycotic aneurysm; Pasteurella; Capnocytophagia


Mycotic aneurysms and vasculitis are serious, life-threatening complications of infections. Mycotic aneurysm was coined in the late 1800s by Osler in reference to the mushroom shape of an aneurysm in an endocarditis patient; however, “mycotic” referenced the infectious etiology, but not specifically fungal infection. Infected (mycotic) aneurysms are a rare complication of a usually pre- existing vascular defect which can be from atherosclerotic disease, aneurysm, or prosthetic/graft device. Infection can develop from seeding while bacteremic or fungemic, via embolism from Infective Endocarditis (IE), extension from an adjacent infection, or via direct inoculation secondary to trauma. Common locations for vascular infections include the aorta, peripheral, intracranial, and visceral arteries. The incidence of mycotic aneurysm is difficult to estimate but based on studies that rely on autopsy, the incidence may be less than 5% of all aneurysms and it is expected to be much higher in the setting of IE [1,2].

Several species of bacteria can directly cause vasculitis and mycotic aneurysm and some are transmitted from dogs and cats through scratches or bites [3-5]. Skin and soft tissue infections are the most frequent infectious manifestations of bite injury, although invasive infections with poor outcomes may occur through direct inoculation or dissemination [6]. This review focuses on vasculitis and mycotic aneurysms caused by Pasteurella and Capnocytophaga.


A literature search was conducted using the following search terms in PubMed/MEDLINE: Pasteurella and vasculitis, Pasteurella and aneurysm, Capnocytophaga and vasculitis and Capnocytophaga and aneurysm. Articles were restricted to the English language and year of publication (January 1, 1996–May 4, 2022). Database query resulted in 48 publications. After title and abstract review, 23 articles were included in this analysis. Fourteen articles reported on Pasteurella vasculitis or aneurysm. Nine articles reported on Capnocytophaga vasculitis or aneurysm. Results of the literature search were independently reviewed by the authors for relevance.

Etiology and Pathogenesis

Pasteurella and Capnocytophaga cause life-threatening infections, including vasculitis and mycotic aneurysms. Pasteurella species are among the most common bacteria that cause infection following dog or cat bite [4,5]. Pasturella are gram-negative facultative anaerobe which are typically short and straight bacilli, although some species may appear as coccobacilli [7]. Capnoctophaga species are unique in that they cause serious infections in immuncompromised patients [8]. Capnocytophaga species are slow growing, gram-negative, fusiform-shaped bacilli with one rounded end and one tapered end [7].

In our review, all 14 reported cases of Pasteurella mycotic aneurysms were diagnosed based on a positive tissue or blood culture [9-22]. Seven of nine reported cases of Capnocytophaga mycotic aneurysm or vasculitis had positive cultures whereas 2/9 was diagnosed using molecular methods (16S ribosomal RNA sequencing or polymerase chain reaction) [23-31]. Because 12/14 (85.7%) reported cases of Pasteurella vasculitis or mycotic aneurysm had bacteremia or preceding infection at other sites, hematogenous seeding is likely how the major vessels were infected. Only three of nine patients with Capnocytophaga vasculitis or mycotic aneurysm had bacteremia or infection at other sites. This could be due to fastidious nature of the bacteria or preceding antibiotic use before samples were obtained for culture.

Clinical Presentation and Diagnosis

It is interesting to note that 10/13 (77%) patients with Pasteurella were sexagenarian (Table 1). The median age of patients with Pasteurella and Capnocytophaga vasculitis or mycotic aneurysm was 61 and 69 years, respectively. Nine of 12 (75%) patients with Pasteuella mycotic aneurysm were males and 5/9 (55.6%) of patients with Capnocytophaga vasculitis or mycotic aneurysm were male.

Ref. Age, sex Risk factor  Comorbid Conditions Vessel involved Associated Pasteurella infection  Antimicrobial  Surgical management  Outcome 
[16] 61, M Owns dogs and cats Rheumatoid arthritis Abdominal aorta  Septic joints, bacteremia  Penicillin G Open surgical repair Died during surgical repair
[21] 61, F Cat bite Not described  Thoracic aorta  None described Not described  Open surgical repair Not described 
[22] 17, M No known animal contact  Renal insufficiency Cerebral aneurysm  Mitral valve endocarditis, bacteremia  Ampicillin  None  Died from CVA
[10] 54, M Dog lick on psoriatic lesions  Cirrhosis, psoriasis Thoracic /abdominal aorta  Bacteremia  Amoxicillin, gentamicin EVAR  Alive 2 years following diagnosis 
[13] 64, M Cats in home  Heavy alcohol abuse Abdominal aorta  Right leg cellulitis  Cefotaxime  Open surgical repair  Alive 1 year after surgery 
[17] 68, M Cat bite  Heavy alcohol abuse Abdominal aorta Right thumb cellulitis, bacteremia  Piperacillin-tazobactam  Open surgical repair Died
[14] 69, F Cat bite Not described Abdominal aorta  Bacteremia  Penicillin G Open surgical repair Alive 8 months following surgery
[18] 61, M Dog lick  Myelodysplastic Syndrome  Abdominal aorta and aortic arch  Bacteremia  Ampicillin  Open surgical repair  Alive 1 year following surgery 
[15] 611, M Dog bite Not described  Descending thoracic aorta aneurysm  Bacteremia  Not described  Open surgical repair  Alive 18 months following surgery 
[20] 57, F  Dog lick and scratch  Cigarette smoking  Cerebral aneurysm  Mitral valve endocarditis, Bacteremia   Penicillin G Open surgical clipping  Alive 4 weeks following surgery
[9] 66, M Cat scratch HCV with cirrhosis Aortic endograft  infection Bacteremia Aortic valve endocarditis Doxycycline and levofloxacin for 3 months None No recurrent infection a year after completing treatment
[11] Not reported Cat bite and cat lick of abdominal surgical wound  Not described Aortic endograft Bilateral psoas abscesses and para-aortic abscess Ceftriaxone 6 weeks followed by doxycycline lifelong Drainage tube placement Complete resolution and no recurrence after 10 months
[12] 68, M A bite from pet rabbit Not described Aortic graft infection None described Cipro for 6 months Open surgery for removal of endograft Cured
[19] 62, M Dog scratch Cirrhosis, Cigarette Smoking Superficial femoral artery Bacteremia, paraspinal abscesses Ceftriaxone Open surgical repair No recurrence 9 months after treatment (our patient)

Table 1: Reported cases of endovascular infections by pasteurella.

Because dogs and cats are primary sources of Pasteurella and Capnocytophaga, history of animal bite or scratch is important. Among 23 Pasteurella and Capnocytophaga cases, 7 had history of animal bite and 8 had history of animal scratch or leaking of wound site (Table 1 and Table 2). Three had cats or dogs but no history of bite and scratch. One had no known animal contact.

Capnocytophaga causes severe illness in patients with splenectomy or immuncompromising illness. Table 2 shows that none of the patients had splenectomy, 1 of 9 patients had HIV and 1 had type 2 diabetes mellitus. This indicates that Capnocytophaga vasculitis or mycotic aneurysm should be suspected in all patients with history of animal exposure and suggestive clinical findings, regardless of immune status.

Ref. Age,sex Risk factor  Comorbid Conditions Vessel involved Associated Capnocytophaga infection  Antimicrobial  Surgical management  Outcome 
[23] 80, F Dog licking excoriation caused by eczema CAD DM (type 2) Nummular eczema Infrarenal aorta* Bacteremia Ceftriaxone, ciprofloxacin None Cured
[24] 49, F Not reported IVDU
HIV HCV CMV retinitis
Hypertension Aortic valve
and ascending aorta replacement for dissection
Descending aorta with rupture Bacteremia Piperacillin/tazobactam Open surgical repair Died
[25] 77, M Dog bite Stroke
Essential thrombocythaemia
Alcohol abuse
L-common femoral artery, popliteal arteries None Piperacillin/Tazobacatam followed by amxillin/clavulate Open surgical repair Favorable
[26] 69, M Dog bite CAD Smoking Infrarenal aorta Bacteremia Purpura fulminans, multiorgan failure Imipenem None No recurrence after one year
[27] 51, F Owns cats but no scratch or bite Achalasia
Spinal stenosis
Thoracic aorta None Ertapenem followed by amoxicillin/clavulanate Open surgical repair Healthy one months after completion of antibiotics
[28] 86, F Contamination of abrasion with dog saliva Aortic valve repair
Bilateral hip replacements
L-common iliac artery (with rupture) None Ceftriaxone followed by amoxicillin/calvulanate Open surgical repair No recurrence at 6 months follow up
[29] 63, M Dog bite Hepatitis A infection Juxtarenal and infrarenal None Ceftriaxone plus ciprofloxacin followed by amxicillin/clavulanate Open surgical repair Stable at 7 months follow up
[30] 65, M Dog scratch and licking of scratch Hypertension CAD Radical prostatectomy
Abdominal aorta None Imipenem followed by ciprofloxacin Open surgical repair Improved
[31] 69, M Dog bite Hypertension
Peptic ulcer disease
Abdominal aorta with rupture None Meropenem followed by ciprofloxacin Open surgical repair Stable at 3 months follow up

Table 2: Reported cases of endovascular infections by Capnocytophaga

Clinical presentation of vasculitis and mycotic aneurysm depends on the vessels involved. Among 14 cases of Pasteurella included in this review, abdominal aorta was involved in 6, thoracic aorta in 3, aortic endografts in 2, femoral artery in 1 and cerebral arteries in 2 (Table 1). Among 9 cases of Capnocytophaga included in this review, 8 had mycotic aneurysm and one had vasculitis (Table 2). Abdominal aorta was affected in 6 patients. Thoracic aorta, common iliac artery and common femoral artery were affected in one patient each.

Patients with abdominal aorta mycotic aneurysm presented from Pastuerella and Capnocytophaga infection may have worsening abdominal pain with or without abdominal pulsating mass, loss of pulse in lower extremities, fever, chills, nausea, vomiting, diarrhea, generalized weakness, hematuria, back pain, bilateral buttock pain, pelvis pain, night sweats, anorexia, weight loss, and/or mental status change [9-14,16-18,23,24,26,29-31]. Patients with thoracic aorta involvement may have anterior chest pain radiating to both axillae, worsening upper abdominal pain radiating to back, fever and/or chills [10,21,27]. Patients with cerebral mycotic aneurysm may present with focal neurologic signs such as hemiparesis, dilated pupil and mental status change. The patients may also have fever, chills, myalgia and anorexia [20,22]. Patients with mycotic aneurysm of common iliac artery, femoral artery or popliteal artery usually present with worsening leg pain, iliac fossa pain, and swelling, [19,25,28]. In patients included in this review, the main diagnostic imaging modality was Computerized Tomography (CT) which was performed n 19/23 (82.6%) of patients. Positron Emission Tomography (PET)-CT was done in 3 patients [24,28,29]. And MRI was done in one patient [23].

Management and Outcome

Effective management of Pasteurella and Capnocytophaga mycotic aneurysm includes both surgery and antibiotics. Among 23 patients included in this review, 17 (74%) had open aneurysm surgery, 2 (8.7%) had drainage placement at the site of abscess linked to aneurysm or endovascular aneurysm repair [10,11] and 4 (17.4%} had no surgical intervention [9,22,23,26]. Among a total 15 patients with detail antibiotic treatment report, two were treated with intravenous (IV) antibiotic for 2 weeks [9,23], four for 4 weeks [13,26,31], two for 5 weeks [14,27], and seven for 6 weeks [11,18-20,28,29,30]. IV antibiotics used for the treatment of Pasteurella mycotic aneurysm include penicillin G, ampicillin, cefotaxime, and ceftriaxone, [9,11,13,14,18,19]. Oral antibiotics such as amoxicillin for 6 weeks, levofloxacin for 12 weeks, or ciprofloxacin for 24 weeks were used for initial treatment in three patients with Pasteurella infection, and these patients treated with oral antibiotics had good outcomes [9,10,12]. IV antibiotics used for treatment of Capnocytophaga vasculitis or mycotic aneurysm include piperacillin/tazobactam, ceftriaxone imipenem, meropenem, ertapenem [23,26-31]. Capnocytophaga produces the -lactamases and use of -lactam/ -lactamase inhibitor combination, advanced cephalosporin classes or carbapenem is important for effective treatment [32].

Among 13 total patients with at least 4 weeks of IV antibiotic course, 6 (46%) received oral suppressive treatment [11,27-30,31]. Five of the six patients who received suppressive antibiotic had open repair of aneurysm with graft placement. Oral suppressive treatment ranged from 4 weeks to life-long and includes antibiotics such as doxycycline for Pasteurella infection and amoxicillin/clavulanate or ciprofloxacin for Capnocytophaga infection [11,27-30,31].

Among reported cases of Pasteurella mycotic aneurysm with known treatment outcome, 10 had favorable outcome and 3 died. In patients with Capnocytophaga vasculitis or mycotic aneurysm, 8 had favorable treatment outcome and 1 died. The mortality from capnocytophaga in patients included in this review is low compared to previous publications which reported mortality rates as high as 29% in patients with history of spelenectomy or alcoholism [33]. This difference could be because most reported patients with vasculitis or mycotic aneurysm had no immuncompromising condition or splenectomy.


Pasteurella and Capnocytophaga species can cause vasculitis and mycotic aneurysm. A thorough clinical history including history of exposure to cats and dogs is important. Imaging studies are useful to detect aneurysm and any findings suggestive of infection. Confirmation of infection requires positive blood or tissue cultures. In most patients, effective management includes surgery and long course IV antibiotics followed by oral suppressive treatment.


Both authors contributed to the writing and revision of this document.


Citation: Etemady-Deylamy A, Abate G (2022) Mycotic Aneurysms Caused by Pasteurella and Capnocytophaga Species. J Vasc Surg. 10:453.

Copyright: © 2022 Etemady-Deylamy A, et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.