A 65-year-old woman in the intensive care unit for the past 8 days for a severe COPD exacerbation complicated by respiratory failure and intubation is being evaluated for a fever. She has a past medical history COPD, hypertension, dyslipidemia and tobacco abuse.
During the fever workup she is found to have culture positive bacteremia due to vancomycin-resistant Enterococcus faecium (VRE) likely from her urinary tract. She has a urinary catheter in place that was exchanged three days ago, and the urine culture is also positive for VRE. The organism has good susceptibility (low MICs) to other antibiotics on the sensitivity report, including penicillin, linezolid, daptomycin and gentamycin, and is not beta lactamase producing.
Her scheduled medications include aspirin, atorvastatin, enoxaparin, prednisone, albuterol, ipratropium, lisinopril, chlorthalidone and amlodipine. She was also recently started on vancomycin and piperacillin/tazobactam.
She has no allergies.
Her vital signs include a temperature of 101 F, pulse 88, BP 115/78 mmHg, and the ventilator is in AC mode at a rate of 12. She is sedated.
Her WBC count is 11.3k/mcL and creatinine is 1.6 mg/dl.
Which of the following is the best choice of therapy for this patient?
A.Daptomycin
B.Ampicillin with or without sulbactam
C.Linezolid
D.Tigecycline
E.Gentamicin
Answer: B – Ampicillin with or without sulbactam
Key point: If the organism is sensitive, using the simplest drug for therapy can help reduce resistance to other broad spectrum antimicrobials and/or maintain effectiveness in those antimicrobials usually reserved for critically ill patients with resistant organisms.
Discussion: Vancomycin-resistant enterococci are common causes of hospital acquired infections, and treatment is challenging due to the variety of clinical conditions which may be encountered (UTI to meningitis), the inherent resistance of enterococci as a group, and the development of multidrug resistance. However, the treatment principles that govern the approach to other HAIs apply here as well. Newer antibiotics are available that have very good activity against enterococci, including VRE, such as linezolid, daptomycin, and tigecycline, but if ampicillin is active against the organism (becoming more rare), it should be considered first for targeted therapy, especially in the situation described in the vignette (septicemia without endocarditis or meningitis). Ampicillin also achieves high urinary concentrations.
The choice of whether or not to use combination therapy is not clear in this situation, but most experts recommend it in the settings of prosthetic valves and/or very prolonged infections or critical illness.
Gentamicin can be used as a part of combination therapy against VRE but should not be first line in this patient both because of the susceptibility report and the patients current kidney function.