Cardiovascular Disease: Student/Resident Case Report Poster - Cardiovascular Disease I |

Mitral Valve Endocarditis Caused by Citrobacter Koseri FREE TO VIEW

Zachary Harris, MD; Astha Chichra, MD
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Tulane University Health Sciences Center, New Orleans, LA

Copyright 2016, American College of Chest Physicians. All Rights Reserved.

Chest. 2016;150(4_S):82A. doi:10.1016/j.chest.2016.08.090
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SESSION TITLE: Student/Resident Case Report Poster - Cardiovascular Disease I

SESSION TYPE: Student/Resident Case Report Poster

PRESENTED ON: Tuesday, October 25, 2016 at 01:30 PM - 02:30 PM

INTRODUCTION: Over two million hospital-acquired (nosocomial) infections occur each year in the United States, and 50-60% are caused by antimicrobial-resistant strains of bacteria.

CASE PRESENTATION: A 67-year-old man presented to the ER with symptoms of confusion, lethargy and worsening somnolence. Medical history included carcinoma of the throat, atrial fibrillation, type-2 diabetes mellitus, COPD, and ischemic stroke. Heart rate, creatinine, WBC and lactate were elevated. Ultrasound revealed B lines and hepatization over the left lower lung. Abdominal CT scan confirmed a consolidative lung process (Figure 1) and revealed an impacted ureteral stone which was surgically treated. Blood and urine cultures were positive for Citrobacter koseri resistant to third-generation cephalosporins, susceptible to meropenem and variably susceptible to piperacillin/tazobactam and ciprofloxacin. Transthoracic echocardiography revealed a vegetative mitral valve mass supporting the diagnosis of bacterial (Citrobacter koseri) endocarditis (Figure 2). The patient responded favorably to a six-week course of IV antibiotics with meropenem.

DISCUSSION: Important organisms that cause nosocomial infections include vancomycin-resistant Enterococci, methicillin-resistant Staphylococci, and Gram-negative isolates with variable resistance patterns. Key Gram-negative resistance patterns arise from extended-spectrum beta-lactamases in enteric bacilli, high-level third-generation cephalosporin beta-lactamase resistance in Enterobacteriaceae and Citrobacter genus, and multidrug resistance in pseudomonads and Acinetobacter genus. Certain Citrobacter isolates, such as C. koseri, produce a small amount of beta-lactamase constitutively, while other Citrobacter species (such as C. amaloniticus) produce beta-lactamase which can mutate to high-level beta-lactamase resistance. Citrobacter causes endocarditis rarely, and only one report of C. koseri mitral valve endocarditis exists in the English language. Fourth-generation cephalosporins, piperacillin/tazobactam, and carbapenems are efficacious therapies for nosocomial infections caused by Gram-negative organisms with high beta-lactam resistance.

CONCLUSIONS: The expanding epidemic of antibiotic resistant nosocomial infections has become a public health crisis. Physicians well-versed in resistance patterns among organisms known to cause these infections are best able to select effective antimicrobial regimens in a timely fashion.

Reference #1: Jones RN. Resistance patterns among nosocomial pathogens: trends over the past few years. Chest. 2001 Feb;119

Reference #2: Lipsky BA, Hook EW 3rd, Smith AA, Plorde JJ. Citrobacter infections in humans: experience at the Seattle Veterans Administration Medical Center and a review of the literature. Rev Infect Dis. 1980 Sep-Oct;2(5):746-60

Reference #3: Weinstein RA. Infections Acquired in Health Care Facilities. In: Kasper D, Fauci A, Hauser S, et al., eds. Harrison's Principles of Internal Medicine, 19e. New York, NY: McGraw-Hill; 2015

DISCLOSURE: The following authors have nothing to disclose: Zachary Harris, Astha Chichra

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