The clinical case is presented of a medical specialist in microbiology, with many years of experience, who accidentally inoculated himself, when performing the antibiogram by the BACTEC MGIT 960 method, with a pure strain of Mycobacterium tuberculosis, isolated from a sputum sample from an ambulant patient of Spanish origin; he pricked himself on the external lateral side of the distal phalanx of the index finger, piercing the glove with the contaminated needle.
At the time of inoculation, he immediately treated the wound (washing with soap and water), and later reported it to the Occupational Risk Prevention Service (SPRL), where the inoculation was recorded as an occupational accident.
At the SPRL, the medical-work history of the injured worker was reviewed and it was noted that she had a positive Mantoux test; analyses and serologies were requested for HCV, HIV and quantified post-vaccination antibodies for hepatitis B; the worker was also informed that if any signs or symptoms compatible with tuberculosis or with problems at the site of inoculation, she should consult the SPRL.
Three weeks later, an erythematous papule appeared at the inoculation site, slightly painful on pressure, which grew to a size of 1.5-2 cm, without axillary lymphadenopathy or general symptoms. (Image 3)
Image 3. Biopsy of the lesion
When the worker observed that the lesion did not improve, she made an informal consultation with the Plastic Surgery Department, which requested a biopsy and excision of the lesion. The anatomical and pathological findings were granulomatous dermatitis with occasional necrosis, highly suggestive of tuberculous dermatitis. (Image 4)
Pathological anatomy: granulomatous dermatitis, suggestive of tuberculous dermatitis.
In the microbiological study, dubious acid fast bacilli were observed, and when cultured in BACTEC MGIT 960, the growth of Mycobacterium tuberculosis was confirmed. Subsequently, both isolates (from the source and from the injured worker) were studied by MIRU (Mycobacterial interspersed repetitive units), confirming the identity of both strains. (Image 5)
Image 5. Microbiological study
The diagnosis of cutaneous tuberculosis was confirmed and the worker was referred to the Internal Medicine Department, where, after being assessed, she began anti-tuberculosis treatment with rifampicin 600 mg, 250 mg of isoniazid and 1500 mg of pyrazinamide on an empty stomach for two months, continuing for a further four months with rifampicin 600 mg and isoniazid 300 mg per day. This service also monitored the patient with monthly analyses in which no alterations were detected, good tolerance to the medication was observed, and she was discharged from the hospital 7 months after starting treatment.
The SPRL reports the occupational disease in accordance with RD 1299/2006, of 10 November, which approves the list of occupational diseases in the Social Security system and establishes criteria for their notification and registration.
