Postsurgical infection with carbapenemase-producing Enterobacterales in a 45-year-old woman

A 45-year-old previously healthy woman was admitted to our hospital for surgical management of a nonhealing traumatic upper extremity injury.Approximately 6 months earlier, she sustained a motor vehicle collision in Nigeria, resulting in open fractures to her right distal humerus, radius, and ulna.At the time of her injury, she underwent irrigation, dbridement, and external fixation of her fractures.She developed a surgical-site infection 2 months later while still in Nigeria, requiring irrigation, dbridement, and internal fixation of her distal humerus.Her radius and ulna remained in nonunion, and her right forearm was casted for several months after removal of the external fixation.She received several courses of antibiotic therapy, the details of which were not available.Shortly after she moved to Canada, the patient presented to the emergency department at her local hospital and was subsequently referred to the orthopedic surgery clinic at our hospital.On examination, she was afebrile, with heart rate of 84 beats/min and blood pressure of 121/68 mm Hg.Her right forearm had a varus deformity and her elbow was fixed in flexion.An extensive surgical incision extended from her right ante cubital fossa to distal forearm, with a few small nondraining regions of dehiscence.She had pain, stiffness, and decreased range of motion.Laboratory investigations demonstrated normal leukocyte count, but C-reactive protein of 96.0 (normal < 5.0) mg/L.Radiographs showed nonunion of the distal humerus fracture with failure of the internal fixation, and nonunion of the radius and ulna fractures.The following week, the patient was electively admitted to our hospital and underwent irrigation, dbridement, and open reduction and internal fixation of the distal humerus, radius, and ulna.Intraoperatively, purulent fluid, bone necrosis, and destruction of the elbow joint were noted.The ortho pedic surgery service started intravenous cefazolin 2 g every 8 hours postoperatively.Operative cultures returned positive for Klebsiella pneumoniae.Our infectious diseases service was consulted to guide antibiotic management.We changed cefazolin to intravenous piperacillin-tazobactam 4.5 g every 6 hours.Antibiotic susceptibility testing demonstrated resistance to all routinely tested antibiotics.Rapid testing for carbapenemase production was positive for New Delhi metallo--lactamase (NDM).We started intravenous ceftazidime-avibactam 2.5 g every 8 hours and intravenous aztreonam 2 g every 8 hours within 6 hours of NDM detection (Figure 1).We obtained emergency telephone approval from Health Canada's Special Access Program (SAP) to access both medications, and had existing stock in our pharmacy that could be started expeditiously while awaiting shipment from the manufacturer.The patient completed 6 weeks of treatment.At follow-up 1 year after surgery, she had reduced pain, a well-healed incision, and normalization of C-reactive protein to 3.6 mg/L.However, she had ongoing stiffness and decreased range of motion. DiscussionGram-negative bacteria are major causes of infection worldwide.The order Enterobacterales comprises the majority of clinically significant gram-negative bacteria, including Escherichia coli, Klebsiella species, and Enterobacter species.Gram-negative bacteria can develop antibiotic resistance through numerous mechanisms.