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A Veterinarian From Vermont Presenting With a Painful Right Index Finger Following a Needlestick Injury That Occurred While Caring for a Dog

Year: 2020

Type: article

Abstract: A 56-year-old female veterinarian in Vermont presented with swelling and pain of the medial aspect of her right index finger. Three weeks prior to presentation, the patient suffered a needlestick injury from a 21-gauge needle to the medial aspect of her distal right index finger that occurred after aspirating fluid from a subcutaneous cystic mass of a dog. The patient was otherwise healthy and was not on any medications. She denied fevers, chills, night sweats, headache, cough, joint pain, or other symptoms of systemic illness. Her vitals were within normal limits and her physical examination was only remarkable for swelling, erythema, and tenderness to palpation in the medial aspect of the distal interphalangeal (DIP) joint of her right index finger (Figure 1). The range of motion of her DIP joint was significantly limited due to pain. Laboratory test results showed a white blood cell count of 5310 cells/µL, an erythrocyte sedimentation rate of 1 mm/hour, and a C-reactive protein level of < 7.0 mg/L. A radiograph showed soft tissue swelling, no soft tissue air or foreign bodies were seen, and the underlying bones were intact. Swelling, erythema, and tenderness of patient’s right index finger. Swelling, erythema, and tenderness of patient’s right index finger. The patient went to the operating room where she had a 4-mm incision made over the medial aspect of the DIP joint. Purulent material was expressed and sent for Gram stain and culture. Biopsies of the subcutaneous fat were taken (Figure 2). Biopsies of subcutaneous fat from patient’s right index finger. Biopsies of subcutaneous fat from patient’s right index finger. What is your diagnosis? Diagnosis: Cutaneous inoculation of Blastomyces following a needlestick injury. Yeast forms consistent with Blastomyces were present on hematoxylin and eosin stain performed on tissue demonstrating 8- to 15-µm, broad-based budding between mother and daughter cells with doubly refractile cell walls (Figure 3). Blastomyces dermatitidis was isolated from fungal cultures as well (Figure 4). On cellophane tape mount, the yeast forms were identified as well as the mold phase with septated hyphae. Biopsies of subcutaneous fat from patient’s right index finger showing broad-based budding between mother and daughter cells with double refractile cell walls consistent with Blastomyces dermatitidis (arrows). Biopsies of subcutaneous fat from patient’s right index finger showing broad-based budding between mother and daughter cells with double refractile cell walls consistent with Blastomyces dermatitidis (arrows). Fungal cultures of patient’s right index finger showing Blastomyces dermatitidis (arrows). Fungal cultures of patient’s right index finger showing Blastomyces dermatitidis (arrows). Blastomycosis is caused by infection with the dimorphic fungus B. dermatitidis. The primary site of infection is usually the lungs following inhalation of conidia, which are phagocytized by alveolar macrophages and transformed from the mycelial to the yeast phase [1]. In some immunocompromised patients, the yeast can then disseminate hematogenously to bone, skin, brain, and the genitourinary tract [1]. The clinical spectrum of illness varies from asymptomatic infection to acute or chronic pneumonia, cough, and fever in addition to bone pain or headaches [1]. Although it is uncommon in humans, primary cutaneous infection from B. dermatitidis has been reported and related to direct inoculation from skin trauma associated with agricultural work, laboratory accidents, and animal bites [2]. In addition to causing disease in humans, B. dermatitidis infects dogs and cats living in endemic regions. In dogs, the illness usually presents in young, male, sporting breeds following inhalation of conidia, and typically causes symptoms of dyspnea, tachypnea, fever, lethargy, and weight loss in addition to pulmonary nodules, uveitis, and draining skin abscesses [3, 4]. There have been 2 case reports previously published describing zoonotic transmission from dogs to veterinarians related to needlestick-type injuries [5, 6]. In both cases, the providers developed localized cutaneous infection from Blastomyces following injuries from a scalpel and needle contaminated with canine lung tissue from dogs with Blastomyces pneumonia. Of note, the dog our patient was caring for was diagnosed with systemic blastomycosis, which confirmed our suspicion that the fungus was transmitted directly from the animal tissue to the patient via the needlestick injury. Our patient was treated with itraconazole for 4 months with complete resolution of her symptoms. It was interesting to note that her urine Blastomyces antigen was positive at first and converted to negative after 1 month of itraconazole. In conclusion, there are 2 unique learning points from this case. First, needlestick injuries to veterinarians have been associated with the transmission of unique pathogens such as nontuberculous mycobacteria, Brucella abortus live vaccine, and Blastomyces [7–9]. It is also plausible that these injuries can transmit arboviruses and Pasteurella species as well [7]. Second, although most providers are aware that B. dermatitidis is found in the same regions as histoplasmosis (midwestern United States), Blastomyces is also endemic in northern New England and southeastern Canada and causes illness in both pets and humans [10]. Potential conflicts of interest. The authors: No reported conflicts of interest. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest.

Source: Clinical Infectious Diseases

DOI: 10.1093/cid/ciaa086