Nontyphoidal Salmonella as a Cause of Mediastinal Abscess in a Patient With Extensive Cardiac Surgery

Abstract

Focal infections caused by nontyphoidal Salmonella (NTS) are relatively rare and usually self-limited. Those with cardiac surgical history are predisposed to intrathoracic seeding, including mediastinal infections and abscesses. We report a case of a 39-year-old Hispanic male with a complex past medical history of Tetralogy of Fallot with an initial presentation of Salmonella gastroenteritis and concern for sepsis. The patient did not clinically improve on ceftriaxone despite appropriate cultures and susceptibilities, and another source of infection was speculated. A chest CT scan showed development of a mediastinal abscess with compression of the right ventricular outflow tract. The patient was not deemed an appropriate surgical candidate and was managed conservatively on ceftriaxone and ciprofloxacin. He was discharged in stable condition. This case of NTS infection associated with a mediastinal abscess is a rare occurrence, and management is complicated. To improve morbidity and mortality, early imaging is essential to diagnose distal seeding of the infection in patients with enteral infections who do not show clinical improvement despite appropriate antibiotic treatment. Surgery is the standard of care, but conservative management might be required in certain high-risk cases.

Keywords: mediastinitis; salmonella; sepsis; tetralogy of fallot.

Figure 1. Contrast-enhanced CT of the chest, abdomen, and pelvis showing mediastinal abscess.

Axial and sagittal postcontrast CT through the chest reveals pulmonary outflow tract reconstruction evident postsurgical material and resultant streak artifact (arrowhead). Anterior to the pulmonary artery outflow tract, hypodense rim enhancing fluid collection is seen suggestive of abscess (A and B, arrows). Mild thickening of mid small bowel loops with surrounding fat stranding is suggestive of enteritis (B, dashed arrow). Urinary bladder wall thickening and inflammatory changes represent cystitis.

Figure 2. CT pulmonary angiogram of the chest showing the mediastinal abscess with a superimposed hematoma.

Axial CT pulmonary angiogram shows a marked increase in size of the anterior mediastinal lesion (A, arrow), which causes encroachment and mass effect on the pulmonary artery outflow tract without active contrast extravasation. Air foci in the anterior mediastinum represent ongoing infection (A, arrowhead). On narrow window settings, hyperdense hematoma is seen abutting the pulmonary outflow tract (B, arrow), in contrast to less dense anterior abscess (B, arrowhead). Expanding hematoma extends to compress the right ventricular outflow tract (C, arrow).