BRIEF REPORT SALMONELLA AGONA INFECTION OF ABDOMINAL AORTIC ANEURYSM G. Lee and E. C. Sweeney
School of Pathology, Trinity College, Dublin 2.
Summary
form aneurysm of the abdominal aorta could be seen extending from below the origin of the renal arteries to the bifurcation. There was minimal perianeurysmal haemorrhage. The aneurysm was lined by soft laminated thrombus and exhibited a 1 cm defect in the wall at the upper anterolateral aspect (Fig. 1). This defect communicated with the lumen of the second part of the duodenum through a short channel lined by thrombus and necrotic tissue. The stomach and duodenum were completely filled with fresh blood clot. The re-
An abdominal aortic aneurysm that became infected during Salmonella agona septicaemia is described. Fatal rupture of the aneurysm into the duodenum occurred. The clinical and pathological aspects of the case are discussed and the current literature on the subject is reviewed.
Introduction In patients with atheromatous abdominal aortic aneurysms, a secondary infection may occasionally occur within the wail of the aneurysm and its lining of blood clot. Persistent fever and positive blood cultures in such cases may give rise to a clinical suspicion of bacterial endocarditis. Up to the end of 1974 22 cases had been recorded in which the infection was caused by Salmonella species (Kanwar et al, 1974). We report here a case in which the infective agent was Salmonella agona, a comparatively noninvasive organism and one not previously implicated in the infection of aneurysms.
Case Report A 76-year old female was admitted to hospital complaining of vomiting, diarrhoea and abdominal pain for one week. She was mildly dehydrated, but physical examination was otherwise unremarkmarkable. Symptomatic treatment for the vomiting and diarrhoea was ineffective and over the next few days the patient became pyrexial (101 ~ F) and developed evidence of basal pneumonia. Relevant laboratory data at this time included a WCC of 12,300/mm 3 (90% neutrophils), an ESR of 68/h and isolation of Salmonella agona from the faeces. The pyrexia and diarrhoea continued and the clinical course was complicated by the development of multifocal ventricular ectopics and transient episodes of mental confusion. Salmonella agona was repeatedly isolated from the faeces and once from a blood culture. The patient was treated with ampicillin 500 mg q.d.s, orally for the first 10 days and the last 4 days of her hospital stay. This was given for respiratory infections. Thirty days after admission, the patient died from a massive haematemesis. At autopsy, a retroperitoneal mass measuring approximately 15x10x10 cm was observed pushing forward the duodenum and the root of the mesentry. On removal of the abdominal organs a 10x5x5 cm fusi-
Fig. 1 - - S a g i t t a l section of aneurysm showing communicating rupture (R) between lumen of aorta (A) and duodenum (D). The posterior wall of the aneurysm (which is artefactually folded) shows atheroma and fibrous thickening lined internally by old thrombus.
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mainder of the gastrointestinal tract was normal. The aorta exhibited severe and extensive atheroma and the coronary arteries were similarly affected, though no occlusion was seen. A swab and a fragment of the wall of the aneurysm were cultured and SalmOnella agona was isolated from both. Microscopically, sections showed the typical features of an atheromatous aortic aneurysm. In the region of the rupture, however, the aortic elastic lamina and intact adventitia petered out and were replaced by thrombus and necrotic tissue containing numerous microabscesses. No bacteria were identified on relevant sections stained by Gram's method. Discussion
Epidemiological studies cf human Salmonella infections in the United States and Britain indicate an overall incidence of approximately 10 cases per 100,000 population a year (Aserkoff et al, 1970; Communicable Disease Surveillance Centre (CDR) 1978). The increase in the incidence of such infections abroad and in this country has been attributed to greater consumption of deep-frozen and processed food and to intensive animal husbandry (Barry, 1975). The rarity of human Salmonella agona infections in Britain prior to the importation of infected fishmeal (for animal feeding) in 1970 has been commented upon previously (O'Keefe et al, 1978). It is interesting that Salmot~efla agona is now one of the commonest species infecting poultry in Britain (CDR, 1978). Infection of aortic aneurysms by Salmonella organisms is well recognised and is most commonly associated with Salmonella choleraesuis serotype (Kanwar et al, 1974). To the best of our knowledge Salmonella agona has not been recorded as causing this type of infection before now.
it is likely that the infection of the aneurysm occurred via the blood stream during the bacteraemic phase of this patient's illness. Another possible route of infection that has been suggested was direct spread from lumbar Salmonella osteomyelitis, a condition that has coexisted in a large percentage of the cases recorded to date (Kanwar et al, 1974). In our case, however, the vertebral bodies were normal. Microabscesses and tissue necrosis were identified in the aneurysm wall only around the defect. We feel, therefore, that the infection at this point was responsible for Iocalised weakening of the wall of the aneurysm and ultimately for its rupture. The majority of patients with this condition have been elderly and have died of overwhelming infection or rupture of the aneurysm. Two of 8 recorded individuals who had prosthetic replacement of the diseased aorta had long-term survival (Kanwar et al, 1974). Greater awareness of this complication in elderly individuals with salmonellosis who fail to respond to conventional therapy should lead to earlier institution of surgery and to diminished mortality. References Aserkoff, B., Schroeder, S. A. and Brachman, P. S. 1970. Salmonellosis in the United States-five year review. Am. J. Epidemiol. 92, 13. Barry, M. J. 1975. Two-year survey of Salmonella in a Dublin hospital. Irish Med. J. 68, 18. Communicable Disease Report (CDR). 1978. Communicable Diseases Surveillance Centre, London. Kanwar, Y. S., Vinod, M., Anderson, B. R. and Pilz, C. G. 1974. Salmonellosis associated with abdominal aortic aneurysm. Arch. Intern. Med. 134, 1095. O'Keefe, M., Gleeson, D., Lee, G. and Whelton, M. J. 1978. Salmonella agona osteomyelitis of the spine. Irish J. Med. Sci. 147, 36.
School of Pathology, Trinity College, Dublin 2.
Summary
form aneurysm of the abdominal aorta could be seen extending from below the origin of the renal arteries to the bifurcation. There was minimal perianeurysmal haemorrhage. The aneurysm was lined by soft laminated thrombus and exhibited a 1 cm defect in the wall at the upper anterolateral aspect (Fig. 1). This defect communicated with the lumen of the second part of the duodenum through a short channel lined by thrombus and necrotic tissue. The stomach and duodenum were completely filled with fresh blood clot. The re-
An abdominal aortic aneurysm that became infected during Salmonella agona septicaemia is described. Fatal rupture of the aneurysm into the duodenum occurred. The clinical and pathological aspects of the case are discussed and the current literature on the subject is reviewed.
Introduction In patients with atheromatous abdominal aortic aneurysms, a secondary infection may occasionally occur within the wail of the aneurysm and its lining of blood clot. Persistent fever and positive blood cultures in such cases may give rise to a clinical suspicion of bacterial endocarditis. Up to the end of 1974 22 cases had been recorded in which the infection was caused by Salmonella species (Kanwar et al, 1974). We report here a case in which the infective agent was Salmonella agona, a comparatively noninvasive organism and one not previously implicated in the infection of aneurysms.
Case Report A 76-year old female was admitted to hospital complaining of vomiting, diarrhoea and abdominal pain for one week. She was mildly dehydrated, but physical examination was otherwise unremarkmarkable. Symptomatic treatment for the vomiting and diarrhoea was ineffective and over the next few days the patient became pyrexial (101 ~ F) and developed evidence of basal pneumonia. Relevant laboratory data at this time included a WCC of 12,300/mm 3 (90% neutrophils), an ESR of 68/h and isolation of Salmonella agona from the faeces. The pyrexia and diarrhoea continued and the clinical course was complicated by the development of multifocal ventricular ectopics and transient episodes of mental confusion. Salmonella agona was repeatedly isolated from the faeces and once from a blood culture. The patient was treated with ampicillin 500 mg q.d.s, orally for the first 10 days and the last 4 days of her hospital stay. This was given for respiratory infections. Thirty days after admission, the patient died from a massive haematemesis. At autopsy, a retroperitoneal mass measuring approximately 15x10x10 cm was observed pushing forward the duodenum and the root of the mesentry. On removal of the abdominal organs a 10x5x5 cm fusi-
Fig. 1 - - S a g i t t a l section of aneurysm showing communicating rupture (R) between lumen of aorta (A) and duodenum (D). The posterior wall of the aneurysm (which is artefactually folded) shows atheroma and fibrous thickening lined internally by old thrombus.
407
408
IRISH JOURNAL OF MEDICAL SCIENCE
mainder of the gastrointestinal tract was normal. The aorta exhibited severe and extensive atheroma and the coronary arteries were similarly affected, though no occlusion was seen. A swab and a fragment of the wall of the aneurysm were cultured and SalmOnella agona was isolated from both. Microscopically, sections showed the typical features of an atheromatous aortic aneurysm. In the region of the rupture, however, the aortic elastic lamina and intact adventitia petered out and were replaced by thrombus and necrotic tissue containing numerous microabscesses. No bacteria were identified on relevant sections stained by Gram's method. Discussion
Epidemiological studies cf human Salmonella infections in the United States and Britain indicate an overall incidence of approximately 10 cases per 100,000 population a year (Aserkoff et al, 1970; Communicable Disease Surveillance Centre (CDR) 1978). The increase in the incidence of such infections abroad and in this country has been attributed to greater consumption of deep-frozen and processed food and to intensive animal husbandry (Barry, 1975). The rarity of human Salmonella agona infections in Britain prior to the importation of infected fishmeal (for animal feeding) in 1970 has been commented upon previously (O'Keefe et al, 1978). It is interesting that Salmot~efla agona is now one of the commonest species infecting poultry in Britain (CDR, 1978). Infection of aortic aneurysms by Salmonella organisms is well recognised and is most commonly associated with Salmonella choleraesuis serotype (Kanwar et al, 1974). To the best of our knowledge Salmonella agona has not been recorded as causing this type of infection before now.
it is likely that the infection of the aneurysm occurred via the blood stream during the bacteraemic phase of this patient's illness. Another possible route of infection that has been suggested was direct spread from lumbar Salmonella osteomyelitis, a condition that has coexisted in a large percentage of the cases recorded to date (Kanwar et al, 1974). In our case, however, the vertebral bodies were normal. Microabscesses and tissue necrosis were identified in the aneurysm wall only around the defect. We feel, therefore, that the infection at this point was responsible for Iocalised weakening of the wall of the aneurysm and ultimately for its rupture. The majority of patients with this condition have been elderly and have died of overwhelming infection or rupture of the aneurysm. Two of 8 recorded individuals who had prosthetic replacement of the diseased aorta had long-term survival (Kanwar et al, 1974). Greater awareness of this complication in elderly individuals with salmonellosis who fail to respond to conventional therapy should lead to earlier institution of surgery and to diminished mortality. References Aserkoff, B., Schroeder, S. A. and Brachman, P. S. 1970. Salmonellosis in the United States-five year review. Am. J. Epidemiol. 92, 13. Barry, M. J. 1975. Two-year survey of Salmonella in a Dublin hospital. Irish Med. J. 68, 18. Communicable Disease Report (CDR). 1978. Communicable Diseases Surveillance Centre, London. Kanwar, Y. S., Vinod, M., Anderson, B. R. and Pilz, C. G. 1974. Salmonellosis associated with abdominal aortic aneurysm. Arch. Intern. Med. 134, 1095. O'Keefe, M., Gleeson, D., Lee, G. and Whelton, M. J. 1978. Salmonella agona osteomyelitis of the spine. Irish J. Med. Sci. 147, 36.
