Spontaneous Septic Embolic Encephalitis and Endophthalmitis in a Recovering Polytrauma Patient: A Case Report and in a Recovering Polytrauma Patient:

: In polytrauma cases with thoracic injury and long-term chest tube drain, there is a risk of pulmonary arteriovenous fistula formation, which mostly remains undiagnosed. The pulmonary arteriovenous fistulas lead to the right to left shunt and could be a potential source of systemic septic embolism. Here, we describe a recovering polytrauma patient, who spontaneously developed septic embolic encephalitis and endogenous endophthalmitis, with no evident source of septic systemic embolism. We suspect the pulmonary arteriovenous fistulas due to thoracic injury or chest tube drain could be the possible source of septic systemic embolism, which needs to be evaluated in such cases after excluding common causes.


Introduction
Septic embolism is a critical but often under-reported class of infectious complications. It can be associated with various early and late sequelae. The common causes are bacterial endocarditis, septic thrombophlebitis, central venous catheter, and periodontal infection. However, other intravascular devices can also act as a source of infection and embolism [1]. Immediate complications are the vascular occlusion of the downstream vasculature like cerebral, myocardial, or bowel infarction [2]. Abscesses and mycotic aneurysms are most common among the late complications [3].
Here we want to highlight pulmonary arteriovenous fistulas as a possible source of spontaneous septic embolism in the patient with thoracic injury and chest tube drain.

Case Report
A 23-year-old male patient with a history of road traffic accident presented to the emergency department with multiple fractures, right-side pneumothorax, and shock. After initial resuscitation, a chest tube drain was placed. In view of increasing respiratory distress, the patient was intubated and then shifted to ICU for further management. Empirical antibiotics (ceftriaxone and amikacin) were started and a central venous catheter was secured for vasopressor support. He was tracheostomized on day five of presentation, in view of poor lung conditions and prolonged ventilation. On blood culture, Pan-drug resistant Klebsiella pneumonia was reported which showed sensitivity to colistin, but differential time to positivity was less than 120 min and the string test was negative, for which a central venous catheter was changed and injection Meropenem and Colistin were started.
The patient was gradually improved and on day eight of presentation; he was weaned off from the ventilator with a GCS (Glasgow coma scale) of E4VTM6. On the next day, he spontaneously developed right eye redness and pupil haziness for which fundoscopy was done and, in view of suspicion of endogenous endophthalmitis, an intravitreal injection of colistin and vancomycin were started. On the same day, his GCS also started deteriorating for which brain magnetic resonance imaging (MRI) was done, showing multiple emboli to the brain (see Figure 1). An abdominal computed tomography (CT) scan was also done, which did not show evidence of any solid organ abscess (see Figure 2). Infective endocarditis and the presence of shunt were ruled out by transesophageal echocardiography (see Figure 3). The septic shock gradually worsened and the patient died on day twelve of presentation.

Discussion
Most of the cases of septic embolic encephalitis and endogenous endophthalmitis are due to infective endocarditis or cardiac shunt and remaining others are because of indwelling catheters. However, our patient had normal transesophageal echocardiography and there was no evidence of indwelling catheters as a source of septic embolism. Another possibility could be a klebsiella invasive syndrome, but there was no evidence of solid organ abscess on the CT scan and the string test for the hyper-viscous colony (a marker of hyper-virulence) was also negative [4].
The possible explanation of the presented case is the presence of a chest tube drain that could have led to systemic embolization by pulmonary arteriovenous fistulas. The pulmonary arteriovenous fistulas occur when pulmonary arteries directly drain into pulmonary veins, bypassing the capillary circulation and form right to left shunt, and can be the potential cause of systemic embolism. The trauma to the thoracic wall or pulmonary vessels by penetrating injury, including chest tube drainage, can lead to systemic or pulmonary arteriovenous fistulas, which can be diagnosed by selective angiography or contrast-enhanced magnetic resonance imaging. The therapeutic angiographic embolization or surgical excisions of the fistulas are the treatment modalities [5,6].

Conclusion
Systemic septic embolism is a serious complication with a high fatality rate. Sometimes the source of systemic embolism goes undetermined. In polytrauma cases with thoracic injuries and chest tube drain, we suspect a much higher incidence of pulmonary arteriovenous fistulas as a potential source of systemic embolism than reported and should be investigated after the exclusion of common causes.