[340, 341, 342]. Ocular involvement with syphilis and neurosyphilis are seen more frequently in AIDS patients [343]. The commonest ocular finding of syphilis in HIV patients is posterior segment involvement and include posterior uveitis, retinitis, optic neuritis or papilloedema secondary to neurosyphilis [344–348].

16.5.1.6  Treatment

Penicillin is the mainstay of treatment of syphilis [336]. The preparation, dose, and duration of treatment will vary with the stage of syphilis and the presence of associated limiting factors or complications such as concurrent HIV infection. For primary, secondary, or early latent syphilis, Penicillin G benzathine administered at a dose of 50,000 units/kg IM has been recommended. The adult dose of 2.4 million units should not be exceeded. For late latent syphilis, an adult dose of 50,000 units/kg IM weekly for three weeks may be used. For neurosyphilis, HIV-infected patients with abnormal CSF examination, syphilitic scleritis, posterior uveitis, or optic neuritis, treatment may consist of Penicillin G sodium 2.4 million units every 4 h IV for 10–14 days [349] or penicillin G procaine 2.4 million units/day IM plus probenecid 500 mg po every 6 h both for 10–14 days [349].

As newborns do not exhibit sensitivity to penicillin, no alternative antibiotic is used. The clinical stage of the disease and the presence of neurosyphilis should be considered. Close monitoring of the clinical status of syphilitic lesions during treatment might be required as worsening of chorioretinitis and stromal keratitis can occur during the course of therapy. The following treatment regimens have been recommended: Penicillin G sodium 50,000 units/kg every 8–12 h IV for 10–14 days or Penicillin G procaine 50,000 units/kg/day IM for 10–14 days or Penicillin G benzathine 50,000 units/ kg I.M in a single dose.

16.5.2  Tuberculosis

Mycobacterium tuberculosis is the most common infectious cause of death worldwide accounting for 10 million fatalities each year [350, 351]. Infected immigrants appear to be responsible for a recent increase in the number of cases in the United States [351]. The

human immunodeficiency virus (HIV) pandemic also appears to be responsible for aggravating this problem and may also be responsible for increasing microbial resistance to antibiotics [352, 353]. Tuberculosis can cause ocular complications, and if not diagnosed early and treated promptly, it can lead to severe visual loss. Because the disease is treatable, awareness and knowledge of its ocular complication should be of concern to ophthalmologists who are expected to encounter more of these cases.

Mycobacteria are nonmotile nonspore forming, pleomorphic, weakly gram positive rods 1–5 mm long, typically slender and slightly bent. Some appear beaded and some are clumped. In general, species pathogenic for humans are more acid fast, have greater nutritional requirements, grow more slowly, and are more sensitive to chemotherapeutic agents.

16.5.2.1  Ocular Manifestation

Involvement of the eye in tuberculosis is likely to occur either by direct invasion or due to hypersensitivity reaction [354, 355]. The organism can produce disease in any portion of the eye, and clinical manifestations are nonspecific. In primary tuberculosis, ocular involvement without systemic features can occur. Manifestations are limited to the ocular surface with corneal and conjunctival involvement in the form of phlyctenulosis, ulcers, masses, or interstitial keratitis.

However, in secondary tuberculosis, direct and hematogenous spread of the infection can occur, leading to systemic infection. Possible ocular manifestations in patients with pulmonary disease include anterior uveitis, vitritis, choroiditis, choroidal tubercles, retinal vasculitis with vascular occlusion, and papillitis [356, 357]. A clinical picture of endophthalmitis or panophthalmitis has been reported [358]. Multifocal choroiditis, although rare, is recognized and can support the diagnosis of miliary or disseminated disease [356, 359].

16.5.2.2  Diagnosis

Presumptive diagnosis of ocular disease can be made based on the finding of acid-fast bacilli during microscopic examination of a diagnostic specimen as a