Linezolid-Induced Black Hairy Tongue

A Case Report and Review of Literature

Abstract

Black hairy tongue is an asymptomatic and benign condition presenting with black-to-brownish discoloration of the dorsum of the tongue with elongated filiform papillae. Several medications, particularly antibiotics, are implicated in its causation. Xerostomia, abnormal desquamation of the tongue, use of oxidizing mouthwashes, excessive intake of nicotine, coffee, and tea, and immunosuppressive states predispose to the development of this condition. Herein, we describe a case of a young female who developed black hairy tongue within 5 days of linezolid intake. The discoloration disappeared after 7 days of stopping the drug. We also summarize the various reports of black hairy tongue due to linezolid in a tabular form. We aim to highlight the importance of medication history in the identification of this uncommon condition. We also emphasize identifying risk factors for this condition and educating the patients about them.

INTRODUCTION

Black hairy tongue is also known as lingua villosa nigra. It is a benign condition characterized by hypertrophied filiform lingual papillae with black discoloration of the dorsum of the tongue. It is usually asymptomatic but few patients may experience halitosis, nausea, tickling, and dysgeusia. It is caused due to defective desquamation.[¹] Various factors such as male sex, old age, smoking, alcohol use, and poor oral hygiene are considered predisposing factors. Medications such as cephalosporins, penicillins, sulfonamides, methyldopa, and linezolid have been reported to cause black discoloration of the tongue.[²]

Herein, we report a rare case of black hairy tongue due to linezolid in a young female which occurred in a short duration. We also review the literature regarding black hairy tongue due to this antibiotic.

CASE REPORT

A 29-year-old female developed a solitary, unilateral swelling on the left side of the neck for 3 weeks. It was initially 2 cm × 2 cm, which gradually progressed to 4 cm × 4 cm. It was associated with mild pain and moderate-to-high-grade fever. For these complaints, she visited a quack, who performed incision and drainage and prescribed tablet paracetamol 500 mg twice daily with tablet linezolid 600 mg twice daily. The patient did not give a history of taking any other medications.

Five days later, the patient developed blackish discoloration of the dorsum of the tongue. On examination, brownish-to-black discoloration on the posterior part and dorsal aspect of the tongue was noticed with elongated and hypertrophied filiform papillae, with complete sparing of the margins of the tongue [Figure 1]. Examination of teeth, gums, buccal mucosa, lips, and palate revealed no abnormality. Nail and hair examinations were normal.

Figure 1: Black–brown discoloration of the dorsum of the tongue with elongated papillae

Complete hemogram and serum Vitamin B12 levels were normal. Scraping for fungal elements and culture for bacteria and Candida was negative. Serology for human immunodeficiency virus (HIV) was nonreactive. Consent for biopsy was not given by the patient.

A diagnosis of linezolid-induced black hairy tongue was made. The patient was advised to stop linezolid and clean her tongue thrice a day with normal saline. She was also referred to the department of tuberculosis (T.B.) and respiratory medicine, where she was investigated and her cartridge-based nucleic acid amplification test for T.B. was positive. She was started on antitubercular treatment for tubercular lymphadenopathy.

The discoloration totally disappeared after 7 days of stopping linezolid [Figure 2].

Figure 2: Complete resolution of discoloration of the tongue after 7 days of stopping linezolid

DISCUSSION

Black hairy tongue was first described by Dr. Amatus Lusitanus as early as 1557. Black hairy tongue is caused by several drugs such as antibiotics (penicillins, tetracyclines, macrolides, linezolid, and metronidazole); antipsychotics; antidepressants; antineoplastic agents; and other drugs such as methyldopa.[³] Immunosuppressive states such as HIV, late stages of cancer, and radiotherapy in the head-and-neck area are also associated. The use of oxidizing mouthwashes, excessive intake of black tea, coffee, tobacco chewing, smoking, and alcohol intake are said to increase the risk of this condition. Conditions causing xerostomia and those preventing normal desquamation (trigeminal neuralgia causing pain in mastication, soft diets, and edentulous patients) may also lead to black hairy tongue.[⁴]

The patient presents with tongue discoloration with elongated filiform papillae which may reach a centimeter or more in length. The discoloration is usually black or brown but green, yellow, and blue discoloration of the dorsal tongue has also been described. Antibiotics may alter normal bacterial flora and lead to the growth of chromogenic bacteria such as Porphyromonas gingivalis (a Gram-negative anaerobic bacillus that produces porphyrins).[⁴⁵] In addition, antibiotics may themselves stain the tongue or may lead to the growth of fungi, as evidenced by the growth of Candida from the throat and tongue swabs in case reports. Restricted movements of the tongue or xerostomia may cause excessive accumulation of keratin. Penicillin also decreases nicotinamide production by inhibiting intestinal bacteria, which may lead to hyperpigmentation of the tongue.[⁴]

Linezolid is a synthetic oxazolidinone antibiotic. It binds to bacterial rRNA, thereby inhibiting protein synthesis. It has a broad-spectrum antibacterial activity against infections caused by vancomycin-resistant Enterococcus faecium, Staphylococcus aureus-induced hospital-acquired pneumonia, etc., Usual adverse effects associated with linezolid include peripheral and ocular neuropathy, anemia, and thrombocytopenia due to bone marrow suppression, hyperlactatemia, diarrhea, nausea, and headache. Black hairy tongue is a rare side effect seen in patients receiving linezolid therapy.[⁶⁷⁸] Linezolid-induced black hairy tongue has been reported previously. The details of the previously reported cases are summarized in Table 1.

Table 1: Reported cases of linezolid-induced black hairy tongue

Black hairy tongue is a spontaneously resolving benign condition. The condition is managed by maintaining good oral and dental hygiene. If the condition persists, gentle cleansing with a soft toothbrush and baking soda or hydrogen peroxide is advised.[²⁰²¹] Trichloroacetic acid, urea solution, thymol, gentian violet, and Vitamin B have also been used. Antifungals were tried by some authors based on positive fungal cultures in a few cases but are usually not indicated. The offending drug may be stopped. However, the culprit drug may be reintroduced if the physician deems it necessary.

Black hairy tongue is an uncommon and transient adverse effect of linezolid. Diagnosis of this condition and identification of the cause requires a thorough history of all medications. The patients who may be at risk must be identified and educated regarding prevention. All patients on linezolid therapy should be instructed to maintain good oral hygiene.

Declaration of patient consent

The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient has given her consent for her images and other clinical information to be reported in the journal. The patient understands that her name and initials will not be published and due efforts will be made to conceal identity, but anonymity cannot be guaranteed.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.