Infectious Diseases II

Patient Case

A 72-year-old woman with a history of end-stage renal disease is admitted to the medical ICU with signs

and symptoms of sepsis. Blood cultures are obtained in which two of two bottles grow gram-positive cocci.

The patient is initiated on vancomycin, and her tunneled dialysis catheter is removed. On day 4 of therapy,

the blood cultures are finalized to be MRSA with the following antibiotic susceptibility results: oxacillin

greater than 4 mcg/mL – R; vancomycin 2 mcg/mL – S; daptomycin 0.5 mcg/mL – S; and linezolid 1 mcg/

mL – S. A transthoracic echocardiogram is obtained, which reveals echodensities on the mitral valve. The

patient will be treated medically with antibiotics for 4–6 weeks. The patient’s repeat blood cultures are cur-

rently no growth. Her vital signs and laboratory values are as follows: blood pressure 150/90 mm Hg, heart

rate 88 beats/minute, temperature 100.2°F, WBC 11 x 103 cells/mm3, and lactate 1.1 mmol/L. Which is the

most appropriate treatment regimen?

Definition

Fever: A single temperature of 101°F (38.3°C) or greater orally or a temperature of 100.4°F (38.0°C)

or greater orally for more than 1 hour

Neutropenia: Less than 500 neutrophils/mm3 or less than 500 neutrophils/mm3 during the next 48

hours

Patients presenting with febrile neutropenia undergo initial risk assessment for serious complications

to determine appropriate treatment. Depending on risk, treatment of patients can vary in

administration (intravenous vs oral antimicrobials), duration, and setting (outpatient vs hospital).

Patients are stratified into high- vs low-risk categories on the basis of clinical criteria, including

duration of neutropenia, ANC at presentation, presence of comorbidities, presence of renal and/or

hepatic dysfunction, medication use, and history of febrile neutropenia.

The Multinational Association of Supportive Care in Cancer (MASCC) score is a tool used for risk

stratification.

The MASCC score assigns values to patient age, history, outpatient vs inpatient status, severity

of fever and neutropenia, and presence of comorbidities. Scores of 21 or greater equate to low-

risk status, whereas scores of less than 21 signal high-risk status.

end-organ function, and an expected duration of neutropenia less than 7 days.

Patients considered at high risk present with an ANC of less than 100 neutrophils/mm3, duration of

neutropenia expected to last longer than 7 days, end-organ dysfunction, and comorbidities.

Initial therapy should include monotherapy with an intravenous antipseudomonal β-lactam (i.e.,

cefepime, piperacillin/tazobactam, meropenem, imipenem). Patients with type 1 hypersensitivity

should be treated with either ciprofloxacin or aztreonam plus vancomycin.