A Novel Approach Targeting Coagulase-Negative Staphylococcal Infections: Rifabutin's Antibacterial Potential

Coagulase-negative staphylococci (CoNS) are opportunistic pathogens that pose a significant chal-lenge in healthcare settings, particularly among patients with indwelling medical devices. Their ability to form biofilms and exhibit resistance to β-lactam antibiotics, including methicillin, limits treatment options. The increasing prevalence of multidrug-resistant CoNS necessitates alternative therapeutic strategies. This study aimed to evaluate the in vitro antimicrobial activity of rifabutin against clinical isolates of CoNS, including Staphylococcus epidermidis, Staphylococcus saprophyticus, Staphylococcus haemolyticus, Staphylococcus hominis, and Staphylococcus lugdunensis.

A total of 70 clinical CoNS isolates were collected from patients at King Abdulaziz University Hospital in Jeddah, Saudi Arabia. Identification and susceptibility profiling were performed using the Vitek 2 system. The antimicrobial activity of rifabutin was assessed using the broth microdilution method to determine the minimum inhibitory concentration (MIC). Rifabutin was prepared in 5% dimethyl sulfoxide (DMSO) and tested in serial two-fold dilutions, with MIC values recorded as the lowest concentration that inhibited bacterial growth. Each experiment was conducted in triplicate to ensure reproducibility.

The MIC values of rifabutin ranged from 0.016 to 0.063 µg/mL across the tested strains, with the majority of isolates showing an MIC of 0.0312 µg/mL (41.4%) and 0.063 µg/mL (37.1%), while a smaller proportion ex-hibited an MIC of 0.016 µg/mL (21.4%). The MIC distribution demonstrated consistent inhibitory effects of rifabutin across different CoNS species, with only a 1- to 2-fold variation in susceptibility. These findings suggest that rifabutin is effective against CoNS with a relatively uniform susceptibility profile, making it a promising candidate for the treatment of infections caused by these bacteria.

Rifabutin demonstrates promising antimicrobial potential against CoNS, highlighting its potential as an alternative therapeutic agent for CoNS-related infections. Given its ability to overcome β-lactam resistance mechanisms, further studies, including in vivo assessments, are warranted to explore its clinical applicability.