Tsukamurella pulmonis bacteremia in a young patient with epidermolysis bullosa: A case report

Abstract

Tsukamurella species are rare, aerobic, gram-positive actinomycetes that are increasingly recognized as opportunistic pathogens affecting immunocompromised patients, such as those suffering from epidermolysis bullosa. Epidermolysis bullosa is a rare genetic disorder characterized by skin fragility that predisposes patients to chronic wounds and recurrent skin infections. The case of interest in this work was a 22-year-old male with a complex medical history, including the aforementioned disorder. He was admitted to the hospital’s emergency department, presenting with fluctuating low-grade fever and recurrent bleeding of the skin lesion on his flank. Infectious workup was sent, after which appropriate intravenous fluids were administered for resuscitation, along with broad-spectrum antibiotics. During the patient’s hospitalization, he was found to have Tsukamurella pulmonis and methicillin-resistant Staphylococcus aureus bacteremia, which was treated with vancomycin administered intravenously. Treatment resulted in significant improvement. This case adds to the limited body of studies describing T. pulmonis as a human pathogen. It highlights the importance of considering such rare opportunistic infectious agents in immunocompromised patients with chronic wounds and indwelling catheters. The study serves as a reference for clinicians, emphasizes the therapeutic challenges encountered in managing this infection in high-risk populations, and sheds the light on the need for established policies and clinical guidelines.

1. Introduction

Tsukamurella species are aerobic, gram-positive, weakly acid-fast actinomycetes that can cause a spectrum of infections, including pneumonia, bacteremia, and catheter-related infections.^[1,2] Although such infections are rare, they have been increasingly reported in immunocompromised patients, particularly those with hematologic malignancies, dependent on indwelling catheters, or undergoing chronic immunosuppressive therapy.^[3,4,5] Among Tsukamurella species, Tsukamurella pulmonis is exceedingly uncommon, with only a limited number of case reports describing bacteremia or invasive infections involving this bacterium.^[6,7]

Meanwhile, epidermolysis bullosa (EB), a group of rare genetic disorders characterized by skin fragility, predisposes patients to chronic wounds and recurrent skin infections, most commonly with infection from Staphylococcus aureus and Pseudomonas aeruginosa, as well as to a frequent need for invasive procedures, such as the placement of central venous catheters.^[8,9] To these incidences, the current study adds a unique case of T. pulmonis bacteremia in a young adult with EB and multiple comorbidities to determine the diagnostic and management challenges encountered in treating this vulnerable patient population. This study sheds the light on the need for more research on Tsukamurella and for established clinical guidelines for rare cases such as this one.

2. Case report

A 22-year-old male with a complex medical history of EB, chronic glomerulonephritis (GN) (failed mycophenolate in the past and currently on chronic prednisone treatment, 40 mg daily), chronic normocytic anemia requiring regular blood transfusions every 2 weeks on average (multifactorial: chronic inflammation, frequent blood loss from fragile skin, and hematuria from GN), and a recently diagnosed pulmonary embolism (PE) was admitted to the emergency department. He was referred from a hematology clinic where he was scheduled for a blood transfusion, which was postponed because he presented with a fever (101°F, or 38.3°C). The patient and his mother reported a history of fluctuating low-grade fevers, typically 100°F to 101°F (37.8°C–38.3°C), often associated with physical exertion. He had been mostly bedbound but had engaged in increased physical activity in the few days prior to admission. He also described a chronic and recurrent bleeding lesion on his left flank, which had required suturing on two separate occasions in the preceding week, as well as a recent fall resulting in painful skin denudation of his buttocks. He denied headaches, shortness of breath, cough, abdominal pain, dysuria, or other new symptoms.

On arrival at the emergency department, the patient was tachycardic (heart rate: 118 beats per minute) but hemodynamically stable with a blood pressure of 131/74 mmHg. Oxygen saturation was 96% on room air. A physical exam revealed extensive skin wounds all over the patient’s body, wrapped in dressing but with exposed skin having diffuse ulcerated erythematous wounds of various sizes. Laboratory studies revealed anemia (hemoglobin 6.4 g/dL, hematocrit 21.6%), hypokalemia (3.3 mEq/L), and mild hyperbilirubinemia (1.3 mg/dL). Urinalysis was positive for hematuria and showed >1900 red blood cells and proteinuria (300 mg/dL). Lower extremity x-rays showed no evidence of acute fracture but indicated a chronic deformity of the left foot. Chest x-ray was unremarkable. Initial management at the emergency department included an infectious workup covering blood cultures, the administration of appropriate intravenous fluids and vancomycin, and two units of packed red blood cells.

This admission to the emergency department (November 2024) followed a recent hospitalization (2 weeks before current admission) due to a leaking percutaneous endoscopic gastrostomy tube, during which the PE was incidentally discovered on computed tomography (CT) of the chest (Figure 1A). He was also found to have had an acute kidney injury on top of chronic GN, likely secondary to IgA nephropathy/C3GN. Abdominal lymphadenopathy, noted on CT of the abdomen, was attributed to his EB by his hematologist. He was discharged on therapeutic anticoagulation with enoxaparin (Lovenox: 1 mg/kg twice daily (dosage based on weight), 40 mg twice a day), 40 mg of prednisone daily, and 500 mg of cephalexin every 6 hours for presumed cellulitis to be administered through a peripherally inserted central catheter (PICC line).

Figure 1.

Computed tomography angiogram of the chest. (A) During recent hospitalization (2 weeks before current admission), filling defect (red arrow) within the segmental branch of the right lobe consistent with a segmental pulmonary embolism (PE). (B) During current hospitalization, a right middle lobe segmental pulmonary arterial filling defect (red arrow) consistent with PE.

Blood cultures were drawn on admission. On day 3 of hospitalization, the cultures grew T. pulmonis, and subsequent cultures grew methicillin-resistant S. aureus (MRSA). The T. pulmonis isolate was sent to a reference laboratory for sensitivity testing, which took a few weeks to result (Table S1, http://links.lww.com/IDI/A77). A repeat CT angiogram of the chest on day 3 of hospital stay confirmed the previously diagnosed right middle lobe PE (Figure 1B), confirming the need to carry on with therapeutic anticoagulation. Given that the patient had recurrent bacteremia with multiple organisms and was immunosuppressed with EB, infective endocarditis was a primary concern. Differential diagnoses included infective endocarditis and possible PICC line infection, with the possible entry point being a soft tissue infection due to the repeated skin breakdown. However, both transthoracic and transesophageal echocardiograms were deferred due to the patient’s extensive comorbidities, painful skin fragility, and history of esophageal strictures. After extensive multidisciplinary discussions, a CT of the heart was performed on day 10 of hospitalization. The examination was limited by motion artifacts but did not reveal definitive valvular vegetations, masses, or thrombi. The patient’s PICC line was removed on day 3 of hospitalization, replaced with new one after the blood cultures cleared. He was discharged on day 12 of hospital stay on a four-week course of intravenous vancomycin (1250 mg every 24 hours). Therapeutic anticoagulation was restarted with apixaban (Eliquis). On follow-up, the patient completed the treatment course and continued monitoring consultations with the hematology team for blood transfusions.

Written informed consent to publish the clinical information and image in the journal was obtained from the patient.

3. Discussion

This case adds to the limited literature describing T. pulmonis as a human pathogen. Most reported cases involve immunocompromised hosts, especially patients with malignancy, HIV/AIDS, or long-term corticosteroid use.^[3,5,6] Our patient’s susceptibility was multifactorial, encompassing underlying EB with recurrent skin breakdown, chronic anemia requiring transfusions, immunosuppression from corticosteroids, and the presence of chronic central indwelling venous catheter. These risk factors likely facilitated bloodstream invasion by T. pulmonis.

The accurate identification of Tsukamurella species using standard microbiologic methods is difficult, leading to frequent misclassification.^[1,2] Due to overlapping phenotypic characteristics, the bacteria are often misidentified as members of the genus Nocardia, Corynebacterium, or Rhodococcus.^[1,10] Molecular techniques, such as 16S ribosomal ribonucleic acid sequencing or Matrix-Assisted Laser Desorption/Ionization Time-of-Flight mass spectrometry, have improved detection but are not always widely available.^[9]

The clinical course of Tsukamurella bacteremia can mimic that of more common pathogens, such as S. aureus or Nocardia species.^[3,6,10] Our patient initially presented with nonspecific fever and anemia, which, in the context of his comorbidities and prior hospitalization, raised concerns about a broad range of possibilities, including catheter-related bloodstream infection, soft tissue infection from chronic wounds, and infective endocarditis. The concurrent growth of MRSA from subsequent cultures underscores the polymicrobial nature of infections in EB patients and the difficulty of attributing symptoms to a single organism.

Notably, increased exertion (which our patient had prior to presentation) may exacerbate EB symptoms because of the mechanical stress, friction, trauma, and heat that trigger skin blisters or deeper epidermal layer damage. Moreover, the daily prednisone taken for several weeks prior to admission could have contributed to our patient’s immunocompromised state and increased susceptibility to an opportunistic infection such as T. pulmonis bacteremia.

There are no standardized treatment guidelines for Tsukamurella infections. Prior reports have suggested variable susceptibility to aminoglycosides, macrolides, imipenem, and vancomycin.^[4,6] In the absence of standardized guidance, antimicrobial susceptibility testing is paramount. Empiric vancomycin was continued for our patient given MRSA coinfection and coverage against Tsukamurella. The removal of the infected central line was also crucial, as catheter-related infection is the most common route of bacteremia.^[4,5] Although echocardiography is the diagnostic standard for ruling out infective endocarditis, imaging was limited by the patient’s painful skin fragility and esophageal strictures. A CT of the heart, while nondefinitive, provided reasonable reassurance in this context. This situation highlights the importance of tailoring diagnostic approaches to a patient’s unique clinical limitations.

Patients with EB represent a uniquely susceptible population due to their impaired skin barrier, chronic wounds, and frequent need for central venous access. In this population, recurrent infections are a leading cause of morbidity and mortality.^[8,9] Our case illustrates how unusual pathogens such as T. pulmonis can complicate the course of EB, necessitating high clinical suspicion and close multidisciplinary collaboration. This case also underscores the importance of considering rare opportunistic pathogens such as T. pulmonis in immunocompromised patients with chronic wounds and indwelling catheters. Accurate diagnosis requires advanced microbiological techniques, and management hinges on a combination of targeted antimicrobial therapy, the removal of infected devices, and individualized diagnostic strategies when standard procedures are contraindicated. Clinicians caring for patients with EB should maintain vigilance against atypical organisms, as early recognition and intervention may prevent significant morbidity. Reporting such cases expands the clinical understanding of Tsukamurella infections as well as the infectious complications associated with EB. In addition, these findings highlight the need for institutional protocols that encourage early involvement of infectious diseases specialists and the use of advanced microbiological diagnostics in high-risk patients. They also underscore the importance of further research into the epidemiology, risk factors, and optimal management of rare opportunistic infections in patients with EB.

Author Contributions

Chloe Lahoud and Lindsay Shogan were involved in the conception and design of the study, data analysis and interpretation, and manuscript writing. Aysan Sattarzadeh, Erica Abidor, Rabindra Dhakal, and Joaquim Noguer participated in study design, data analysis and interpretation, manuscript writing and revision. Neville Mobarakai contributed to conception, design, data interpretation, writing, revision, and review of the manuscript. All authors approved the final version for publication.

Conflicts of Interest

None.

Data Availability Statement

The corresponding author can provide data from this patient’s diagnostic and therapeutic journey upon reasonable request.

Supplementary Material

idi-6-166-s001.docx ^{(16.3KB, docx)}

Funding Statement

None.