A Sixty-Nine-Year-Old Female With Serratia marcescens Infection

Serratia marcescens is a bacterial pathogen that tends to cause opportunistic infections, mainly in immune-compromised patients. In this case, we present a 69-year-old female who presented to the emergency department (ED) at Mount Sinai Hospital in Chicago on February 11th, 2022, after a mechanical fall. She had a medical history of metastatic lung cancer treated with chemotherapy, hypertension, pulmonary embolism, polysubstance abuse, and chronic obstructive pulmonary disease (COPD). The patient was found to be positive for systemic inflammatory response syndrome (SIRS). The patient was then started on broad-spectrum antibiotics, including vancomycin and cefepime. Blood cultures were ordered and came back positive for Serratia marcescens. This patient had multiple factors for immune suppression, including metastatic lung cancer, chemotherapy, and polysubstance abuse. The infectious disease department was consulted for the blood culture results, and ceftriaxone was recommended. Later on, levofloxacin was recommended. Blood cultures were negative two days after being positive. Afterward, the patient was kept for monitoring until discharge. Serratia marcescens is found in several reservoirs in nature. Therefore, preventing contact with this pathogen in immune-compromised patients can be difficult. It is important to have a degree of clinical suspicion for opportunistic pathogens like Serratia marcescens whenever a patient with factors for immune compromise presents for any condition.