Primary Cutaneous Tuberculosis after a Needlestick Injury from a Patient with AIDS and Undiagnosed Tuberculosis

Case Report

A 48-year-old, white registered nurse, who was previously healthy, reported suffering a 1-cm superficial laceration of her left forearm. The laceration resulted from a metallic needle, which had previously been inserted into the port of a central-line catheter of a patient with the acquired immunodeficiency syndrome (AIDS). The lesion oozed a few drops of blood and was immediately washed with water and an iodine solution. Zidovudine (Retrovir, Burroughs Wellcome Co., Research Triangle Park, North Carolina) administration was started within 2 hours of the incident and was continued at a dose of 200 mg every 4 hours. The nurse denied direct contact with the patient's secretions before the injury and did not provide nursing care for this particular patient after her injury. She tested negative for human immunodeficiency virus (HIV) antibody on that same day.

The patient with AIDS was supported by a ventilator at the time of the incident. His respiratory failure had been attributed to a severe episode of Pneumocystis carinii pneumonia for which he was receiving therapy. A sputum smear obtained on the day of the nurse's laceration was positive for acid-fast bacilli and subsequently grew 2+ (10 to 100 colonies) of Mycobacterium tuberculosis on culture. A blood culture grew more than 100 colonies of M. tuberculosis per milliliter via the isolator lysis-centrifugation system (Dupont Corporation; Wilmington, Delaware). The patient died early the next day without having ever received antituberculosis therapy. His tests for both hepatitis B surface antigen and VDRL were negative. The M. tuberculosis organisms isolated were not resistant to isoniazid, rifampin, or ethambutol.

The nurse interrupted her zidovudine therapy after 10 days secondary to a severe headache. During the next 5 weeks, she noted increasing erythema with subsequent abscess formation at the laceration site, along with fevers to 38.9 C (102 F). The abscess was incised, and despite treatment with dicloxacillin (Dynapen; Bristol-Meyers-Squibb, New Brunswick, NJ), it failed to heal. Fungal and standard bacterial cultures were repeatedly negative. Six weeks after the incident, a 2-cm, tender left axillary lymph node had developed, and an intradermal, intermediate-strength purified protein derivative showed a positive reaction of 15 mm of induration. The same skin test done 4 months earlier in the nurse had been negative. A chest roentgenogram was normal. Laboratory testing showed a normal complete blood count and a slightly increased Westergren sedimentation rate. A punch biopsy of the lesion showed granulomatous inflammation with Langerhans giant cells and acid-fast bacilli by Fite stain. A culture of the biopsy yielded 43 colonies of M. tuberculosis, sensitive to isoniazid, rifampin, and ethambutol.

The nurse was treated with isoniazid, rifampin, and pyrazinamide with resolution of her skin lesion, fevers, and axillary adenopathy during the following month. The pyrazinamide was administered for 2 months, whereas the isoniazid and rifampin were continued for a total of 6 months. Her HIV antibody test has remained negative 12 months after the incident.

Discussion

This case shows a classic example of primary cutaneous tuberculosis, a rare presentation of tuberculosis. Skin is resistant to tuberculous infection, and a break in the skin barrier must be present for the infection to take place [1]. Once the traumatized skin of a previously uninfected person is inoculated with M. tuberculosis, a tuberculous chancre develops at that site within 3 weeks. A painless regional lymphadenopathy becomes prominent 3 to 6 weeks after inoculation, and a previously negative, intradermal, intermediate-strength purified protein derivative test converts to a positive test [1]. The diagnosis is established by showing acid-fast bacilli on smear or tissue stain, by standard M. tuberculosis cultures, and by classic histologic appearance.

Most cases of primary cutaneous tuberculosis occur on the face or extremities where scratches or preexisting skin disorders are exposed to M. tuberculosis [1, 2]. Ear piercing [3], ritual circumcision [4], tattooing [5], administering intramuscular injections [6], and even mouth-to-mouth resuscitation [7] have been cited as routes for inoculation of M. tuberculosis. In most instances, the injured skin is exposed to M. tuberculosis through infected droplets coughed onto the skin [3-7]. Other well-described entities are the prosector's wart and paronychia, which are acquired through direct handling of tuberculotic cadavers [2].

The treatment of primary cutaneous tuberculosis has varied over the years from irradiation alone [1]; irradiation and surgery [1]; isoniazid alone for 12 months [7]; isoniazid and para-aminosalicylic acid for 18 months [8]; and isoniazid plus rifampin for an unspecified period [2]. None of the modern reports contains enough patients to permit controlled therapeutic tests of chemotherapy. Indeed, the most recent English language report we encountered [2] was published in 1978. Further, the prognosis has been good in most cases regardless of therapy. Modern experience with pulmonary and extrapulmonary tuberculosis has shown that a 6-month regimen consisting of isoniazid, rifampin, and pyrazinamide for 2 months, followed by an additional 4 months of isoniazid and rifampin, produces excellent results when the organisms are sensitive [9]. The same regimen should probably be effective in most patients with primary cutaneous tuberculosis when resistant tuberculosis is not a major concern.

Our patient is of particular interest because it is the first case report of probable blood-borne transmission of tuberculosis and the first reported case of documented needlestick transmission of M. tuberculosis from a patient with AIDS. The offending needle was contaminated with blood containing more than 100 M. tuberculosis organisms per milliliter at the time of the incident. It is likely that blood-borne M. tuberculosis bacilli were directly inoculated into the nurse's skin with the needle.

This case is also remarkable for the lack of simultaneous HIV seroconversion by the nurse. Hepatitis B virus [10] and Cryptococcus neoformans [11] have both been transmitted through needlestick injury from patients with AIDS to health care workers without simultaneous HIV seroconversion. In all instances, differences in infectivity and pathogen load probably account for the selective transmission of these agents (hepatitis B virus, C. neoformans, and M. tuberculosis) without the simultaneous transmission of HIV.