Keywords
Aeromonas sobria - Fournier's gangrene - hematopoietic transplant infection - HSCT - necrotizing fasciitis
Introduction
Bacteremic infections in the post-hematopoietic stem cell transplantation setting are predominantly due to Gram-negative organisms in the Indian context.[1]
Aeromonas bacteremia in patients with malignancy is associated with a higher mortality rate than bacteremia caused by other organisms.[2]
Aeromonas sobria has been reported to cause fulminant necrotizing fasciitis in patients with neutropenia[2] in only a few pieces of literature. Here, we report a rare case of fulminant A. sobria bacteremia with necrotizing fasciitis and Fournier's gangrene.
Case
Fifty-year-old normotensive euglycemic male, case of relapsed pre-B cell acute lymphoblastic leukemia in complete clinical remission, who had undergone unrelated peripheral stem cell transplant 9/10 matched and discharged post-white blood cell (WBC) engraftment a month ago with graft versus host disease prophylaxis with mycophenolate mofetil and dexamethasone, presented to us on day +37 with lethargy and bilateral lower limb pain of 3 days duration, without any fever. He had decreased appetite and decreased urine output. On admission, his hemodynamics were stable and the blood workup revealed neutrophilic leukocytosis (WBC 21,000/mm3), thrombocytopenia (15,000/mm3), deranged kidney function test (urea 118 mg/dL, creatinine 2.1 mg/dL), and mild hyponatremia (Na 129 mmol/L). He had progressive thrombocytopenia and worsening of kidney function with anuria requiring hemodialysis. Aerobic and anaerobic sets of blood cultures were sent and started on empiric antibiotics with cefoperazone and sulbactam. His thrombocytopenia worsened to 7,000/mm3 without any bleeding episodes and required platelet transfusion. On day 5 of the admission, he had altered sensorium, atrial fibrillation with cardiac arrest, for which he was intubated, revived, and required triple inotropic support. The anti-infective regimen was escalated to meropenem, polymyxin B, teicoplanin, and anidulafungin, pending the culture report. His blood culture flagged Gram-negative bacilli in the aerobic bottle. There was an appearance of blisters over both the lower limbs and swelling and redness of the right lower limb that was more in the thigh region, scrotal swelling with erythema, and breach in the skin. The Gram-negative bacteria grown in the blood was identified as A. sobria sensitive to cephalosporins, including ceftazidime, cefepime, piperacillin-tazobactam, and cotrimoxazole, quinolone, aminoglycoside but resistant to imipenem and meropenem. Because of the refractory sepsis, antibiotics were escalated to ceftazidime-avibactam, ciprofloxacin as a dual coverage against the Aeromonas. Clindamycin was added to cover anaerobes and potential Gram-positive organisms. The patient had a rapid downhill course with multiorgan dysfunction. Unfortunately, surgical intervention could not be performed, due to the hemodynamic instability. He succumbed to Aeromonas sepsis. As per literature, sepsis occurs due to a serine proteinase secreted by A. sobria.[2] Similar to the isolate in our case isolated carbapenem resistance has been reported.[3]
Conclusion
Aeromonas spp. should be considered as a causative agent of necrotizing fasciitis and Fournier's gangrene in hematological malignancy patients on immunosuppressants and examination of lower limbs and genitalia is critical to clinch early diagnosis and carry out prompt intervention as necessary as it carries a high mortality rate. Isolated carbapenem resistance should be looked for. Further studies are needed to look for the role of other supportive therapies to mitigate the probable toxin-mediated virulence of A. sobria.
