Efficacy and Cost Comparison of Ertapenem as Outpatient Parenteral Antimicrobial Therapy in Acute Pyelonephritis due to Extended-spectrum Beta-lactamase-producing Enterobacteriaceae

Outpatient parenteral antimicrobial therapy (OPAT) programs are becoming an increasingly popular trend in clinical practice as they offer several benefits to both patients and health-care setups. While OPAT is an established clinical practice in the Western world, the concept itself is alien to patients in India as they prefer the security of hospitals to receive antibiotics over OPAT. We evaluated the clinical response and cost comparison of ertapenem under OPAT versus inpatient settings in patients with extended-spectrum beta-lactamase (ESBL)-positive acute pyelonephritis (APN) given the increasing importance of optimizing both hospital beds and overall cost of patient care in India. APN was chosen as the indication to be studied as it is one of the common complicated urinary tract infections treated in our OPAT unit requiring 10–14 days of parenteral therapy with an agent active against various Gram-negative bacilli and multidrug-resistant organisms. One hundred patients were retrospectively studied based on whether antibiotics were administered during hospital stay alone (hospital only), during both hospital stay, and also as OPAT post discharge (hospital/OPAT) or as OPAT alone (OPAT only). Response to ertapenem and cost of treatment in inpatient versus OPAT settings were compared using Pearson's Chi-square or Fisher's exact test for categorical variables. ANOVA (or Kruskal–Wallis) was used for continuous variables. Baseline urine cultures were ESBL positive with 98% prevalence of Gram-negative bacilli (GNB). Colony counts were ≥100,000 in 74% patients. Only ertapenem, imipenem, and meropenem showed 100% sensitivity to ESBL-positive GNB in baseline urine culture and sensitivity reports. Ertapenem showed 100% sensitivity and complete clinical resolution for 96% patients with APN due to ESBL Enterobacteriaceae. It was administered as OPAT in 90% patients and significantly reduced overall treatment costs.