Cutaneous Rhodococcus equi Infection in an Immunocompetent Host: A Case Report

TL;DR

A 53-year-old woman with a normal immune system developed skin infections caused by Rhodococcus equi, highlighting the need for molecular testing in diagnosing such rare cases.

Contribution

This case report expands the known clinical presentation of Rhodococcus equi to include cutaneous infections in immunocompetent individuals.

Findings

Rhodococcus equi can cause cutaneous lesions in immunocompetent hosts.

Molecular diagnostics confirmed the infection when traditional methods failed.

Targeted antimicrobial therapy led to clinical improvement.

Abstract

Rhodococcus equi is a zoonotic Gram-positive bacterium that can affect immunocompetent hosts and only rarely presents with cutaneous lesions resembling other granulomatous dermatoses, such as cutaneous mycobacterial infections, deep fungal infections, sarcoidosis, and foreign body granulomas.

This report describes a 53-year-old immunocompetent woman who developed recurrent ulcerated nodules on the left lower extremity following recreational travel to southern Mexico. Initial diagnostic studies were nondiagnostic, and molecular analysis using polymerase chain reaction targeting the 16S rRNA gene confirmed infection with Rhodococcus spp. The patient received targeted antimicrobial therapy with subsequent clinical improvement.

This case supports considering Rhodococcus equi as a potential etiologic agent in persistent or relapsing granulomatous skin lesions, regardless of immune status, and demonstrates the utility of molecular diagnostics when conventional histopathologic assessment and culture-based methods fail to establish a definitive diagnosis.

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