394: A CASE OF EXTENSIVE NECROTIZING FASCIITIS DUE TO STRING TEST-NEGATIVE KLEBSIELLA PNEUMONIAE

Abstract

Introduction: Monomicrobial Klebsiella pneumoniae necrotizing fasciitis is rare in North America. The strain that causes necrotizing fasciitis is thought to be hypermucoviscous or hypervirulent K. pneumoniae (hvKP). hvKP is responsible for increasing numbers of cases within the US due to the prevalence of travel and immigration. Description: A 57-year-old Caucasian female with diabetes and history of IV drug use presented to the emergency room with 3 days of left calf pain. Venous doppler was negative for DVT. She was discharged home with medication for musculoskeletal pain. Eleven days later, she returned with worsening left lower extremity pain, edema, and weakness. Physical exam revealed left lower extremity tenderness to palpation and crepitus with scars from drug injections. The laboratory risk indicator for necrotizing fasciitis (LRINEC) score was 9, indicating high suspicion for necrotizing fasciitis. X-ray of the tibia-fibula and femur revealed subcutaneous gas. Broad spectrum antibiotics were initiated, and the patient underwent emergent surgical debridement. Despite aggressive surgical intervention, she continued to worsen with increasing vasopressor requirements due to septic shock. Imaging of the abdomen and pelvis showed extension of the necrotizing fasciitis. Gas was identified within a complex left perirenal abscess, the epidural space and intervertebral disc space of the lower lumbar spine and sacrum, as well as within the urinary bladder. The patient returned to the operating room for further debridement. Wound, blood, and urine cultures yielded Klebsiella pneumoniae and the lab was directed to perform a string test, which was negative. On hospital day two, she had worsening multiorgan failure, and the family elected to withdraw care. Discussion: hvKP with a negative string test is a unique phenotype that is not well described in the literature. Usually, hvKP is identified by a string test and rarely genotyping. Most cases involve patients of Asian descent or recent travel to Asia. As this patient was Caucasian with no recent travel, we suspect that she contracted the organism through IV drug use. The unique aspects of this case may help us understand this new emerging strain in the US.