Abstract
Cardiac surgery is commonly associated with gastrointestinal complications. The incidence of severe abdominal pathology ranges from 0.5% to 3% and is associated with a 30% risk of mortality. Frequently occurring complications include splanchnic infarction, perforated bowel, pancreatitis, upper intestinal bleeding and diverticulitis. Systemic and localised infections are also common after open heart surgery. Plasma proteins, neutrophils, monocytes, endothelial cells and lymphocytes are all altered by cardiopulmonary bypass (CPB). Cell mediated immunity is depressed following exposure to the extra-corporeal circuit leading to an increased susceptibility and vulnerability to pathogens. Typhoid fever is the systemic manifestation of Salmonella typhi septicaemia. Its presentation can be similar to that of abdominal ischaemia making the diagnosis of this potentially fatal multi-systemic illness challenging. We report a fatal case of salmonella septicaemia convincingly masquerading as mesenteric ischaemia following routine CPB.
1. Introduction
Salmonella typhi is transmitted through person-to-person contact or faecally contaminated food or water. Septicaemia may follow a variable incubation period, however, fatal complications of typhoid fever most commonly occur in the second or third week of the illness. Prior to the advent of antibiotics it resulted in a mortality of 10–15% of patients. Treatment with antibiotics has reduced the mortality rate to <1%.
Improved sanitation has steadily decreased the incidence of typhoid fever throughout the developed world. However, it remains endemic in developing countries where sanitary conditions may be poor [1].
Intestinal complications following cardiac surgery are not infrequent, occurring in approximately 2.5% of patients. Often difficult to diagnose during the immediate postoperative period, abdominal pathologies are associated with a high-mortality (33%) and result in 15% of all post-cardiopulmonary bypass (CPB) deaths [2, 3].
We present a challenging case of typhoid fever presenting in a postoperative patient 36 hours after surgery. The symptoms, signs and investigations were suggestive of an intra-abdominal catastrophe. Salmonella bacteraemia was not suspected. This case highlights the extreme difficulty in the management of a patient with salmonella septicaemia owing to its similar presentation to a patient with an intra-abdominal pathology.
2. Case report
A 74-year-old male with a history of angina on exertion was diagnosed with triple vessel disease. Following consultation the decision was taken to perform coronary artery bypass grafting. Whilst awaiting revascularisation the patient travelled to Bangladesh and on his return was admitted for surgery.
Routine revascularisation was performed with the aid of CPB. Trust recommendations for antibiotic prophylaxis were conformed to and the patient received gentamicin (160 mg) and flucloxacillin 1 g on induction. The patient was weaned from anaesthetic and extubated nine hours after surgery. The following morning he was transferred to the high dependency unit.
During the first 36 hours after the operation the patient continued his straightforward recovery. He then developed pyrexia, abdominal pain and distension and passed 1.5 l of loose offensive faecal matter (Fig. 1 ). Owing to this rapid systemic deterioration manifesting in septic shock an abdominal computed tomography (CT)-scan was performed which appeared normal.
Chart outlining the hospital course. Patient developed a postoperative pyrexia and tachycardia associated with the production of explosive diarrhoea. Leucocyte consumption was recorded. Positive stool cultures were available on the third postoperative day following the patients’ demise. preop, preoperative; postop, postoperative; op, operation; WCC, white cell count.
The patient was returned to the intensive care unit where he required intubation, haemofiltration and ionotropic support for cardiorespiratory deterioration. Tazocin, gentamicin and metronidazole were commenced for treatment of presumed intra-abdominal sepsis on microbiology recommendation while a general surgical consult ruled out a perforated viscus, bowel ischaemia or the need for a laparotomy. A blood film revealed the presence of a genuine pancytopenia.
Despite maximal support the patient developed multi-organ failure and died three days after surgery. Microbiology cultures returned postmortem isolated Salmonella typhi in both stool and blood cultures.
3. Discussion
Gastrointestinal complications occur in approximately 2.5% of patients undergoing cardiac surgery. They are associated with a high mortality in the region of 33% and account for nearly 15% of postbypass surgical deaths [2–4].
Differentiating between a benign abdominal complaint and an acute abdomen can be difficult since symptoms and signs are dulled in patients who are ventilated or receiving analgesics. Under such conditions dependence on investigations and imaging may delay early recognition and intervention imperative for improving outcomes precisely in patients in whom effective and timely intervention may be life saving. Results of ‘reactive’ management of abdominal complications are universally poor, with ‘proactive’ intervention having a better outcome [5, 6].
Salmonella typhi is most frequently encountered in the developing world, however, changes in population migration, natural disasters, inner city overcrowding and inappropriate antibiotic administration have led to increased notification of salmonella in the UK. Seventy percent of reported cases of typhoid fever in England and Wales each year are contracted abroad [7].
After an incubation period of 10–14 days non-specific symptoms of fever and malaise develop often resembling a flu-like illness. Abdominal manifestations similar to those of an acute abdomen may then follow with distension, diarrhoea, and constipation being most likely. Pyrexia may then become apparent and in the absence of appropriate treatment results in death in 9–13% of patients [8].
Complications of typhoid fever include those associated with toxaemia which can result in myocarditis, pericarditis, septic shock, hepatic and bone marrow damage. Our patient demonstrated all of the above.
Despite this the diagnosis of typhoid fever remains difficult. It cannot be made on clinical grounds alone and requires a high index of suspicion. Samples of blood, faeces and urine should be cultured and appropriate antibiotic treatment commenced as soon as enteric fever is diagnosed. Ciprofloxacin or ceftriaxone have been used effectively for the treatment of typhoid fever. Our patient was commenced empirically on tazocin, gentamicin and metronidazole during the development of abdominal symptoms. Yet despite sampling of blood, faeces and urine results were not available until after the patient died.
This case highlights the difficulty involved in diagnosing typhoid fever following cardiac surgery. Our investigation and treatment had focused on the suspicion that an intra-abdominal catastrophe had occurred and had not been drawn to the patient’s recent return from an area of poor sanitation. We had also not been informed by his family that gastrointestinal sequelae had developed in the household upon their return from Bangladesh.
Mortality following typhoid fever in untreated patients is high. CPB can lead to increased susceptibility to infection caused by attenuated cell-mediated immunity [9]. Furthermore, it is well-recognised that CPB is associated with gastrointestinal stress ulceration enabling salmonella entry from the bowel to the bloodstream [10]. Our patient appeared to have an increased susceptibility and vulnerability to the pathogen.
This appears to be the first reported case of typhoid fever causing death after cardiac surgery. The rapid onset with which the patient deteriorated resulted in difficulty treating an infection which under normal circumstances can be readily neutralised.
In this case, the diagnosis was hampered by a low index of suspicion of typhoid fever owing to its eradication from the UK. Symptoms and signs suggested an abdominal complication which took time to exclude. In general carrier status should be suspected in patients born in or travelling from endemic areas. Clearly vigilance is required to prevent a recurrence of an essentially preventable complication.
