Candida fungal infection has been receiving more medical attention because of its increasing incidence for the last 25 years mainly because of increasing organ transplantation and chemotherapy in modern era of medicine.1-3 Although Candida albicans is responsible for approximately 50% of all cases, all other candida species can cause local and systemic infection.4 A variety of infection ranging from mucocutaneous candidiasis to more invasive organ infection (endocarditis, endophthalmitis) and abscess development (intraperitoneal and perirenal and brain abscesses) have been reported.5,6
A yeast-like fungus, Candida krusei, once thought to have limited pathogenic potential, has been implicated in endocarditis, ocular infection. Recently, C. krusei fungemia has been noted to occur more frequently in immunocompromised hosts.7 Soft tissue abscess caused by C. krusei is rare, even in immunocompromised hosts.8 We report an extensive soft tissue abscess caused by C. krusei through direct inoculation in an immunocompetent drug abuser.
A 53-year-old man with 35 years of heroin abuse presented to the emergency department in August 2005 because of severe swelling and pain in his right arm. He uses heroin injection daily. Since all veins on his arms are no longer useable, he started to directly inject heroin intramuscularly on both arms. He usually cleans needle and syringe by rinsing in tap water after brief bleach with H2O2. He began to notice tenderness and swelling of right arm a week before, which became progressively worse. He experienced fever (102 F at home), chill, and excruciating pain over the last two days. Medical history included osteoarthritis with bilateral total hip replacements.
In the emergency department, he was not febrile (37.2°C), with a heart rate of 102 beats per minute and a blood pressure of 93/58 mm Hg with mild distress. Clinical examination revealed significant swelling and tenderness around the biceps of right arm, with extensive erythema and multiple open serosanguineous drainage wounds (Fig. 1). Laboratory study disclosed a white blood cell count of 15,200/mm3 (neutrophils, 70%; monocytes, 13%; and lymphocytes, 9%). The patient was initially treated with incision and drainage in OR, which revealed large amount of purple-gray to yellow-tan abscess with no significant muscle infiltrate or damage. After surgical treatment, patient was admitted to hospital Step-down Unit, with local wound packed temporarily. He received parenteral antibiotics including vancomycin and Zosyn while awaiting abscess culture and blood culture reports.
On the second day after admission, microbiology laboratory reported many white blood cells and yeast from Gram stain of abscess sample. Culture later reported large amount of C. krusei. The patient was subsequently switched from antibacterial agents to fluconazole. His condition improved with blood culture later, reporting no growth of any microorganism. After undergoing second surgical debridement on day 4, his condition significantly improved. On day 7, patient was discharged on oral fluconazole for 10 more days and plan of daily dressing change with whirlpool treatment and future wound closure.
Both mucocutaneous and disseminated candida fungal infection are becoming a more important part of total infection pathologies. In settings of immunologically impaired status (malignancy with chemotherapy, organ transplantation with immunosuppressants, and human immunodeficiency virus epidemic) and more intravascular catheter use in hospitals, the incidence is increasing and often life-threatening when severe. Candida krusei, a non-albicans candida species, is considered to be a very rare human pathogen. It accounts for 1% to 2% of all candida fungal infection. However, for the last 25 years, C. krusei received more attention because of its increasing involvement in candida fungal infection, particularly under such conditions as leukemia, diabetes mellitus, and increasing use of chemotherapy and immunosuppressents.9,10 Intra-abdominal abscesses of C. krusei and C. krusei fungemia have been reported.11
Our case deserves attention for several reasons. First, cutaneous and soft tissue infections (fasciitis and abscess) are usually caused by C. albicans12,13 and less frequently by Candida tropicalis.14Candida krusei soft tissue abscess is rare, only reported as abdominal wall abscess in immunocompromised patients.10Candida krusei endocarditis was reported in heroin addicts through intravenous contamination. To our knowledge, soft tissue abscess formation caused by C. krusei through direct inoculation by contaminated intramuscular needle injection has not been reported in the past. Second, the clinical course we observed in this case indicates that C. krusei soft tissue infection cannot only occur but can as well develop severe local abscess with potential systemic invasion in a host with normal defense mechanism. Similar animal study testing relative pathogenicity of C. krusei and C. albicans in rats indicates C. krusei's capability of transforming into an invasive pathogen under immunosuppression.7 This raises awareness of this candida species as a potential virulent fungal pathogen. Last, early C. krusei soft tissue infection in immunocompetent host can be mistakenly treated as bacterial infection. However, worsening of symptoms despite adequate antibacterial treatment combined with history should make us suspicious of possible fungal infection. In patients who develop soft tissue abscess from candida species, surgical intervention associated with appropriate antifungal agent is clearly the best treatment approach.
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