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A 31-year-old man with bilateral blurry vision and floaters
Digital Journal of Ophthalmology 2015
Volume 21, Number 2
May 7, 2015
DOI: 10.5693/djo.03.2014.08.003
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Azin Azabari, MD | Department of Ophthalmology, Stony Brook University
Kevin Kaplowitz, MD | Department of Ophthalmology, Stony Brook University
Patrick Sibony, MD | Department of Ophthalmology, Stony Brook University
Diagnosis and Discussion
Cat-scratch disease is usually a self-limited infection, most commonly caused by an intracellular Gram-negative rod, Bartonella henselae. The estimated incidence of the disease in the US is 9.3/100,000.(5) Although Bartonella infection was historically reported in children,(1) 45% of patients in the database were >18 years of age.(5) The bacteria is transmitted from a young cat through a bite, scratch, or previous break in the skin,(1) although fleas can transmit the disease directly.(6) A nonpruritic papule, usually <1 cm, develops at the inoculation site 3-5 days after exposure, accompanied by flulike illness.(1) Regional lymphadenopathy occurred in 100% of 1,200 cases within 1-2 weeks.(1) It is at this point that bacteremia can rarely lead to systemic complications, which have been reported to occur in every organ system,(7) including encephalitis in 0.2%.(1)

After regional lymphadenopathy, ocular Bartonella infection is the most common manifestation of the disease. Both the presenting and final visual acuity can vary greatly, from 20/20 to counting fingers.(8) The most common ocular presentation is unilateral Parinaud oculoglandular syndrome, consisting of preauricular lymphadenopathy and follicular conjunctivitis, which was reported in 48 of 1200 patients (4%).(1) The second most common ocular finding is chorioretinal infiltrates, reported in 16 of 37 (43%) and 29 of 35 cases (83%) of ocular Bartonella infection.(10,8) Neuroretinitis (optic disc edema accompanied by a stellate pattern of exudative maculopathy) sometimes with peripapillary or equatorial dot-blot hemorrhages, is a classic finding.(8) Although neuroretinitis only occurs in 1%-2% of cases of systemic Bartonella infection,(2,9) a frequently cited study reported neuroretinitis caused by Bartonella in 9 of 14 cases (64%).(11)

Solley et al reported unilateral optic disc edema in 16 of 35 (46%) of ocular Bartonella cases.(8) Chi et al reported bilateral disc edema in only 9 of 53 patients (17%).(12) In their unilateral cases, an afferent pupillary defect was common, occurring in 40 of 44 cases (91%).(12) Optic disc edema progressed to neuroretinitis in 28 of 62 cases (45%).(12) Neuoretinitis is thought to be segmental inflammation of superficial optic nerve head arterioles leading to exudative disc edema, which spreads into the outer plexiform layer. Purvin et al reported unilateral neuroretinitis in 65 of 69 cases (94%).(13) The exudates appear 1-3 weeks after the disc edema and take 2-3 months to resolve.(14)

Omerod noted up to 27 central retinal or choroidal white dots (bilateral in an estimated 75% of cases), usually clearing completely but sometimes leaving pigmented scars: retinal disease was associated with vitritis in 50% and nongranulomatous anterior uveitis in <15% of their cases.(15) Retinal biopsy can confirm that the lesions contain Bartonella colonies.(16) In a relatively large study (n = 35), Solley et al reviewed photographs to determine the depth of infiltrates: 30% occurred in the superficial retina; 49%, in deep retina; 14% were full-thickness; and 7% were in the choroid.(8)

Branch retinal artery occlusion has been reported as frequently as in 11% of 35 cases of ocular Bartonella.(8) There is a case report of a branch retinal venous occlusion(8) and combined central retinal artery and vein occlusion.(17) Less common ocular complications include optic nerve head vasoproliferative, granulomatous angiomas that are composed of superficial abnormal vascular networks in 5% of cases.(10,18). Peripapillary serous retinal detachments, thought to be caused by spreading of fluid from the disc edema, occurred in 20% of 35 cases.(8) The subretinal fluid usually resolves after 2 months.(19) Cases of macular holes and a choroidal detachment have also been reported.(20,21)

Bartonella henselae is difficult to culture. It can be identified with the Warthin-Starry stain, but it is uncommon and usually unnecessary to culture a lymph node.(1,20) Serum indirect fluorescent antibody (IFA) with a titer ?1:64 is 88% sensitive and 94% specific,(20) except in immunocompromised patients, where the sensitivity is <70%.(2) Seroconversion requires 2-3 weeks, and a fourfold rise in titers strongly suggests the diagnosis,(21) although this only occurs in 66% of cases.(22) Although enzyme-linked immunosorbent assay (ELISA) is available to distinguish between IgG and IgM and was initially reported to be 95% sensitive and 100% specific,(21) others report that ELISA is not accurate because of high false negatives.(2,3) The combination of a papule, regional adenopathy, and a positive IFA is 95% sensitive. (22) Tissue polymerase chain reaction can be used as a confirmatory test, because it was reported to be 100% specific and 76% sensitive.(23)

Ancillary testing beyond antibody testing may offer evidence in support of positive diagnosis. Optical coherence tomography can be used to demonstrate optic disc edema and peripapillary subretinal fluid.(19) The chorioretinal infiltrates are hypofluorescent early and hyperfluorescent late on fluorescein angiography but hypofluorescent throughout indocyanine green angiography.(18)

Recommended antibiotics include ciprofloxacin (azithromycin in children),(9) sulfamethoxazole with trimethoprim, and rifampin.(24) A randomized control trial to determine the efficacy of any treatment for ocular Bartonella has not yet been reported. Although investigators have reported using antibiotics for 2-4 weeks with or without steroids,(2) neither appear to improve the visual outcome.(12) One study showed that the final median visual acuity in both treated and nontreated groups was 20/20.(8) The only cases consistently reported to require treatment are immunocompromised patients, who are at higher risk for symptomatic bacteremia. Immunocompromised patients should be treated for at least 1-4 months.(7,25,26)

Final visual acuity depends on the extent of posterior segment involvement. Chi et al reported that of 53 cases with disc edema and a mean presenting visual acuity of 20/160, 36 (68%) had a final visual acuity of 20/40 or better, and 3 (6%) had final visual acuity of 20/200 or worse.(12) While the progression from disc edema to neuroretinitis(12) or a serous retinal detachment(14) does not appear to affect final visual acuity, the presence of a vascular occlusion involving the disc or macula limits the visual outcome.(14) Purvin et al reported that disc edema and macular edema led to a central visual field deficit in 88% of tested cases,(13) but these deficits may not persist after disease resolution.(27) Reed et al reported a case series where all 7 patients finished with final visual acuity of 20/20 to 20/30: subtle residual deficits were detected 2 years later in all 3 of those patients who were tested, including decreased contrast sensitivity, a 30% reduction in the visual evoked potential amplitude, and decreased color vision.(27)

The present case demonstrates the different stages of ocular manifestation of a patient with Bartonella. Unlike previously reported cases, where artery occlusion was noted simultaneous to the retinal infiltrates,(4,15,26) our case showed an unusually progressive course. In addition, initial Bartonella serology for both IgG and IgM were negative, but repeat convalescent titers were positive for both. In patients for whom there is a high clinical suspicion of cat-scratch disease, a convalescent titer should be obtained 2-3 weeks following a negative initial result.