Sandy J. Estrada

Treatment of bacteremia due to Staphylococcus aureus often requires prolonged therapy leading to increased hospital lengths of stay and associated costs. For certain patients, referral to an outpatient parenteral antimicrobial therapy (OPAT) programme serves as an alternative to increased inpatient length of stay. We report an alternative to OPAT using dalbavancin for the treatment of methicillin-sensitive Staphylococcus aureus (MSSA). A 54-year-old Caucasian man was brought to the emergency department from a rehabilitation centre with altered mental status and possible seizure. A peripheral intravenous catheter was placed in the left forearm, and the patient was transferred to the intensive care unit (ICU) for management of his acute psychosis, possible seizure and hyponatremia. Seven days into admission, the patient became febrile thought to be secondary to septic phlebitis of the forearm. Blood cultures were taken and organism identification using Nanosphere Verigene^® BC-GP rapid diagnostic testing resulted in MSSA. The patient received treatment with cefazolin with a planned treatment duration of 14 days but because of the patient's history of alcohol abuse, psychosis requiring hospitalization via the Baker Act, and history of non-compliance to follow-up appointments, the patient was deemed ineligible for OPAT. Due to the limited treatment options, therapy for MSSA bacteremia was changed on day 6 of cefazolin therapy to dalbavancin to complete the 14-day treatment duration. Blood cultures were negative at the end of treatment and no relapse of infection occurred. To our knowledge, this is the first case report using dalbavancin in clinical practice for the treatment of MSSA bacteremia secondary to septic phlebitis. This report highlights the potential role of the newer lipoglycopeptides, such as dalbavancin, in treating patients who require long-term parenteral antimicrobial therapy and are ineligible for treatment via OPAT.

Ceftolozane/tazobactam is a novel antipseudomonal β‐lactam/β‐lactamase inhibitor combination that is currently approved by the United States Food and Drug Administration for the treatment of complicated intraabdominal infections ( cIAI ) and complicated urinary tract infections ( cUTI ). It exhibits bactericidal properties through inhibition of bacterial cell wall biosynthesis, which is mediated through penicillin‐binding proteins ( PBP s). Ceftolozane is a potent PBP 3 inhibitor and has a higher affinity for PBP 1b compared with other β‐lactam agents. Ceftolozane/tazobactam differs from other cephalosporins due to its increased activity against some AmpC β‐lactamases and Pseudomonas aeruginosa . The addition of tazobactam provides enhanced activity against extended‐spectrum β‐lactamase ( ESBL )‐producing Enterobacteriaceae and certain anaerobic organisms. Population pharmacokinetic studies for ceftolozane and ceftolozane/tazobactam are best described by a two‐compartment model with zero‐order input and linear elimination. Similar to other cephalosporins, the best pharmacodynamic property to predict efficacy for ceftolozane/tazobactam is a concentration that remains above the minimum inhibitory concentration ( MIC ) for 40–50% of the dosing interval. For Enterobacteriaceae and P. aeruginosa strains, the time above the MIC (T > MIC ) needed to produce bactericidal activity was much less with ceftolozane than other cephalosporins, with T > MIC requirements of approximately 30%. For currently approved indications, the dose of ceftolozane/tazobactam is 1.5 g (ceftolozane 1 g/tazobactam 0.5 g) intravenously every 8 hours given as a 1‐hour infusion. Ceftolozane has low plasma protein binding (20%) and is predominantly excreted unchanged in the urine (≥92%). Dosage adjustments are required for moderate‐to‐severe renal impairment and in patients receiving hemodialysis. Based on data from clinical trials, adverse effects due to ceftolozane/tazobactam do not differ considerably from other cephalosporins, with the most common being nausea, diarrhea, headache, and pyrexia. Ceftolozane/tazobactam is a promising new agent for the treatment of cIAI and cUTI , including those caused by multidrug‐resistant gram‐negative organisms.