Generic versus branded tigecycline for multidrug-resistant gram-negative bacilli and nontuberculous mycobacterial infections

The increasing prevalence of multidrug-resistant gram-negative bacilli (MDR-GNB) and non-tuberculous mycobacteria (NTM) necessitates effective salvage therapies like tigecycline. While generic formulations offer significant cost savings, clinical data comparing their real-world efficacy against original branded formulations remain limited. This study evaluated the therapeutic efficacy and safety of generic versus branded tigecycline in a resource-limited setting. We conducted a retrospective cohort study at Siriraj Hospital, Bangkok, Thailand, involving adults treated with tigecycline for MDR-GNB or NTM infections. Patients were divided into generic (Tygin®) and branded (Tygacil®) groups. The primary endpoint was 30-day all-cause mortality, with secondary endpoints including microbiological response and safety profiles. Penalized logistic regression and sensitivity analysis were performed to adjust for baseline confounders and identify independent predictors of mortality. A total of 135 patients were analyzed (27 generic, 108 branded). Acinetobacter baumannii was the most common pathogen in this cohort. Thirty-day mortality did not differ significantly between the generic and branded groups (51.9% vs 63.9%). Among non-NTM infections, mortality rates were 59.1% and 66.3%, respectively ( P = .366). The branded tigecycline group demonstrated a higher frequency of concomitant antibiotic use ( P = .018). The generic tigecycline group exhibited a significantly lower incidence of adverse events (48.1% vs 70.4%; P = .018). In multivariate and sensitivity analyses, tigecycline formulation was not associated with mortality. Higher APACHE II scores and Charlson Comorbidity Index were independent predictors of mortality. In this retrospective cohort, clinical and safety outcomes were exploratory and did not demonstrate significant differences between formulations. However, given the wide confidence intervals, clinically meaningful differences cannot be definitively excluded, and these findings warrant validation in adequately powered prospective studies.