Background <p><i>Rhodococcus</i> infections are exceedingly rare and largely reported in immunocompromised hosts, with no consensus on optimal therapy due to limited evidence.</p> Case presentation <p>This article reports for the first time a case of peritoneal dialysis–associated peritonitis caused by Rhodococcus pyridinivorans in a patient with diabetic nephropathy. The dialysate leukocyte count declined substantially with combination antimicrobial therapy, but complete normalization occurred only after replacing icodextrin with a glucose-based dialysate.</p> Conclusions <p>These findings support the use of combination regimens and emphasize the need to consider icodextrin-associated sterile peritonitis when dialysate abnormalities persist despite appropriate antimicrobial treatment.</p>