Mycobacterium chelonae Endogenous Endophthalmitis in a Person Addicted to Intravenous Drugs Presenting as an Intraretinal Peripapillary Granuloma With Tractional Retinal Detachment

Abstract

Purpose:

To report a case of Mycobacterium chelonae endogenous endophthalmitis in a 28-year-old man with recent intravenous drug use that presented as an intraretinal peripapillary granuloma extending from the optic nerve head with an associated macular tractional retinal detachment.

Methods:

Case report.

Results:

Anterior chamber tap yielded aqueous cultures positive for M chelonae. A diagnostic and therapeutic vitrectomy was performed after inpatient hospitalization for 3 weeks to relieve a progressively worsening tractional retinal detachment.

Conclusions:

Atypical causes of endophthalmitis, including nontuberculous mycobacterium, in the population of individuals addicted to intravenous drugs may present with intraretinal peripapillary granuloma associated with a macular tractional retinal detachment. Surgical debulking to relieve anteroposterior traction is an effective treatment option to improve long-term visual outcomes.

Introduction

Endogenous endophthalmitis has been observed in individuals with systemic infection in the setting of intravenous drug use (IVDU). ¹ While endogenous endophthalmitis is often fungal in origin or related to gram-positive bacteria, including Staphylococcus, other less commonly observed organisms, such as nontuberculous mycobacterium (NTMB), have been rarely reported as causative agents. ^2,3 Clinicians should be aware of the broad spectrum of ocular findings that may potentially be associated with NTMB endogenous endophthalmitis, particularly in individuals with a history of IVDU.

Methods

Case Report

A 28-year-old White male presented to an outside hospital with 1 month of blurry vision, 1 week of acutely worsening vision, and 2 days of severe, right-sided ocular pain. When the blurry vision worsened 1 week prior, the patient was seen in an outside emergency department and given topical moxifloxacin for bacterial conjunctivitis. The patient presented to our institution because of worsening ocular pain. On initial ophthalmologic examination, the right eye was noted to have light perception vision, a relative afferent pupillary defect, intraocular pressure of 12 mm Hg by applanation, 3+ conjunctival injection, and 4+ anterior chamber cells with fibrin (by Standardization of Uveitis Nomenclature) ⁴ with posterior synechiae. On fundus examination, there was 3+ vitreous haze (by National Institutes of Health Grading Scale) ⁵ and a white circular granuloma overlying the optic nerve and extending into the vitreous cavity observed in the posterior vitreous. The patient admitted to recent intravenous heroin and cocaine use, and as such, endogenous endophthalmitis was the suspected diagnosis.

The patient underwent aqueous tap for microbiological assessment and then initial treatment with intravitreal vancomycin (1 mg/0.1 mL), amikacin (0.4 mg/0.1 mL), and amphotericin B (50 mcg/0.05 mL) after obtainment of informed consent. Amikacin was used in place of ceftazidime for broad-spectrum antimicrobial coverage because of a history of anaphylaxis after penicillin administration. The patient was noted to have significantly elevated transaminases on presentation and, based on further testing including serologies and viral load, he was diagnosed with hepatitis C. Liver ultrasonography was unremarkable. Blood cultures revealed methicillin-resistant Staphylococcus aureus bacteremia. Magnetic resonance imaging of the orbits with and without contrast was significant for a 4-mm enhancing nodule in the right posterior globe and right uveoscleral enhancement. B-scan ultrasonography revealed mild vitritis and a hyperechoic spherical mass in the vitreous cavity overlying the macula with underlying macular tractional retinal detachment (TRD).

He was admitted for intravenous vancomycin (1.5-g loading dose followed by 1 g every 8 hours for goal trough level of 15-20 μg/mL) and amphotericin B (300 mg in 575 mL of 5% dextrose every 24 hours) for broad-spectrum coverage of suspected endogenous endophthalmitis. Aqueous cultures subsequently grew 3 colonies of Mycobacterium chelonae. At that time, the patient was administered a second intravitreal injection of amikacin (0.4 mg/0.1 mL), and intravenous amphotericin B was discontinued. Pertinent serologic testing were negative for Toxocara canis, HIV, syphilis (rapid plasma reagin), cryptococcal rapid antigen, and mycobacterial blood cultures. Toxoplasma gondii serologies were positive for immunoglobulin G but negative for immunoglobulin M, suggesting a prior infection.

A diagnostic and therapeutic pars plana vitrectomy was performed 3 weeks into his hospitalization because of worsening TRD despite intravitreal antibiotic administration (Figure 1A). TRD was also observed on subsequent B-scan ultrasonography (Figure 1B). During the vitrectomy, a central, white vitreous and retinal lesion associated with a subretinal component, TRD, and subretinal hemorrhage involving the macula were observed. The surgeon (D.S.G.) relieved vitreous traction and debulked the central lesion, which was highly vascular, and intravitreal amikacin (0.4 mg/0.1 mL) was administered. Results from intraocular cultures of the diagnostic vitrectomy were negative, and polymerase chain reaction testing of the vitreous was negative for bacterial or fungal DNA, including NTMB.

Figure 1.

Multimodal retinal imaging in the right eye of a 28-year old man with Mycobacterium chelonae endophthalmitis that was treated initially with intravitreal vancomycin, amikacin, and amphotericin B and complicated by macular tractional retinal detachment. (A) Ultra-widefield fundus photograph on patient presentation demonstrating a posterior pole granuloma and macular retinal detachment. (B) B-scan ultrasonography horizontal axial image showing epiretinal and intraretinal granuloma overlying the optic nerve with tractional retinal detachment involving the posterior pole. (C) Following pars plana vitrectomy and release of anteroposterior traction, there was resolution of the macular retinal detachment and collapse of the peripapillary granuloma. (D) The macula was thin but attached, with a large area of peripapillary thickening on follow-up optical coherence tomography imaging.

Given the patient’s positive aqueous culture for M chelonae on presentation and the patient’s worsening TRD during hospitalization in the setting of an enlarging intraretinal granuloma, the patient’s initial presentation was thought to be due to M chelonae endogenous endophthalmitis. The patient was discharged from the hospital on oral moxifloxacin (400 mg daily).

He was lost to follow-up until 6 months after vitrectomy, when on examination the macula appeared attached, there was nearly complete resolution of subretinal fluid, vision had improved to counting fingers at 1 foot (30 cm), and there were no signs of recurrent inflammation (Figure 1, C and D).

Results

Granulomas extending into the vitreous cavity are rare and have been described with atypical pathogens or diseases associated with granuloma formation, including Bartonella henselae, T canis, Sporothrix schenckii, and sarcoidosis. ^{6 -9} In this case, we report the atypical presentation of M chelonae, an NTMB, as a cause of both endogenous endophthalmitis and intraretinal granuloma.

Although ocular granuloma formation due to tuberculous infection has been reported, the phenomenon is relatively rare. ¹⁰ Interestingly, NTMB-associated infection has been shown to cause insidious seeding of the spine even years after a patient's last IVDU, which suggests the possibility of a latent infection and transient bacteremia that can occur at a later time. ¹¹ It is very likely in a young, immunocompetent patient with no other comorbidities that the infection was due to a recent history of IVDU, potentially due to poor hygienic practices.

In our patient, serologies were subsequently weakly positive (1:32, not considered significant) for T canis. Ocular toxocariasis is a common cause of intraretinal granuloma formation in young children worldwide; however, it is not commonly observed in those with a history of IVDU. ⁷ This emphasizes the point that clinicians should think broadly regarding potential infectious agents in individuals with a history of IVDU who present with signs and symptoms consistent with endophthalmitis. As in this case, endophthalmitis due to NTMB is often treated with intravitreal amikacin; however, initial broad-spectrum antibiotics are warranted until culture results become available.

Prior cases of M chelonae endophthalmitis have rarely occurred after cataract surgery, and in one case, visual acuity was restored with an antibiotic regimen including amikacin, gatifloxacin, imipenem, and clarithromycin. ^{12 -14} However, in cases of retinal traction, as in our case, surgery is often necessary to relieve the traction or to obtain vitreous samples for diagnosis when needed. ¹⁵ Outpatient follow-up in the ophthalmology clinic should be emphasized in this patient population, as nearly half of the patients hospitalized with endogenous endophthalmitis may fail to return after hospitalization. ¹⁶

Our case report demonstrates the rare clinical finding of ocular granuloma formation with concomitant TRD in the setting of M chelonae infection, and we have shown the treatment effect of granuloma debulking and relief of retinal traction on long-term visual outcomes in this uncommon condition.

Conclusions

In this case, we described the presentation of an atypical organism causing endogenous endophthalmitis and highlighted that clinicians should maintain a wide differential diagnosis when considering potential underlying etiologies, particularly in those with a prolonged or recent history of IVDU.