Carbapenem Heteroresistance Mdr Enterobacter Cloacae in a Post-Covid-19 Obese Patient: An Antibiotic Susceptibility Conversion

ABSTRACT

Intro Background: Obesity affects drug delivery and clearance owing to the patient's altered pharmacokinetics. In treating infection, this presents as a conundrum antibiotic dosing to achieve optimal antibiotic concentration at the same time avoiding drug toxicity. Particularly in the case of antimicrobial agents, underdosing may lead to antibiotic resistance. Method(s) Case description We report a case of a morbidly obese (BMI=58) COVID-19 patient infected with carbapenem-sensitive multi-drug resistant (MDR) Enterobacter cloacae bacteremia, treated with ertapenem 1g twice daily and intravenous polymyxin E 9MU stat and 4.5MU twice daily for MDR Acinetobacter baumanii co-infection. He had infected huge grade IV sacral sore one month later in which intraoperative tissue culture grew phenotypically heterogeneous colonies of MDR Enterobacter cloacae with carbapenem-sensitive and carbapenem-intermediate-resistant non-carbapenemase producing colonies. He responded well clinically and biochemically with an increased dose of intravenous ciprofloxacin 800mg BD based on his actual body weight. He was discharged with oral ciprofloxacin 750mg BD for a total of six weeks. Finding(s) Discussion: Obesity is a public health crisis that has reached epidemic proportions. Obesity affects the volume distribution and renal clearance of many drugs including antibiotics. Obese patients are shown to have higher drug clearance than normal-weighted patients resulting in inadequate systemic exposure. This puts patients at risk of developing antibiotic resistant organisms. Our patient, weighing 162kg was given three different beta-lactam antibiotics to treat his infection including ertapenem in which a standard adult dose was given without body weight consideration. Possible underdosing contributed to the conversion of carbapenem susceptibility from sensitive to resistant strain. Conclusion(s) Obese individuals may need a larger ertapenem dose than their non-obese counterparts. Clinical and laboratory assessment may help in monitoring treatment response in this group of patients.Copyright © 2023