**4. Clinical features**

cell wall*,* long straight or curved rods with irregular Gram staining [Figure 1], and specific red-magenta staining characteristic with Ziehl-Neelsen or Kinyoun cold techniques.[Figure 2] They are aerobic and capable of growing in 5 -10% CO2 atmosphere and in blood agar media.[Figure 3] In addition, these microorganisms are arylsulfatase positive, catalase posi‐

tive and niacin negative. [Figure 4]

150 Common Eye Infections

27oC and 5% CO2 atmosphere.

**Figure 1.** Gram positive and irregular stain and forms of *Mycobacterium chelonae*

**Figure 2.** Red-magenta rods of *M. chelonae* in a corneal smear of patient with keratitis.

**Figure 3.** Colonies of *M. chelonae* in agar blood with Brain Heart Infusion (BHI) agar base after 7 days of incubation at

Nontuberculous Mycobacteria can cause infections of all adnexal and ocular tissues. Most atypical Mycobacteria infections are caused by *M. chelonae*, and *M. fortuitum*.

Dacryocystitis and Canaliculitis: Present as epiphora and erythematous swelling in the me‐ dial canthal area, purulent material can be expressed with massage of the lacrimal sac.

Orbital Infections: Present with a gradual development of periorbital edema, without a sig‐ nificant proptosis and a superficial skin lesion may be present. The visual acuity will de‐ pend on the involvement of the optic nerve. [18,19]

Conjuntivitis and Scleritis: Present as conjunctival or as scleral injection and tenderness ac‐ companied with chronic redness, irritation, discharge and pain. Sometimes, marked scleral thinning may develop. Scleral abscesses manifest late in the course of the disease as subcon‐ junctival nodules. [20,21]

Endoftalmitis: Present with severe pain, decreased vision, and redness and discharge, may exist hypopyon, and variable amounts of granulomatous keratitic precipitates. Moderate vit‐ reous inflammation is present in most cases.

Keratitis: The greatest number of recent clinical reports of nontuberculous Mycobacteria oc‐ ular infections are of keratitis, as seen in our hospital (Asociación Para Evitar La Ceguera en México "Dr. Luis Sánchez Bulnes" I.A.P. [APEC]). Keratitis most commonly follows trauma or surgery and has been associated with penetrating keratoplasty and refractive surgery.

Nontuberculous Mycobacteria keratitis is characterized by a delayed onset of symptoms that range typically from 1 to 3 weeks following the exposing event. There is decreased vi‐ sion and an indolent course and some cases various degrees of pain, ranging from indolent to severe.

Presenting symptoms can include any of the following: pain, redness, photophobia, de‐ creased vision, foreign body sensation and/or mild irritation. Presenting clinical signs in‐ clude infiltrates in the corneal interface that can either be multiple white granular opacities <0.5mm in diameter with well defined borders or radiating projections, or a single white round lesion (0.1-2 mm in diameter) which may progress to satellite lesions. These infiltrates spread subsequently into the corneal stroma posteriorly and anteriorly and can result in per‐ foration though the flap to surface. [Table 2].A hypopyon is often found in untreated or poorly treated cases. [25,26]

Lazar and colleagues first described the presence of a "cracked windshield" appearance to the cornea around the edge of the central area of ulceration and infiltrate, seen transiently early in the course of the infection. [25,27,28] This sign consist of radiating lines from the central infiltrate in the middle third of the corneal stroma. It is important to mention that NTM keratitis has also been noted in the abscence of epithelial defect with deep stromal ker‐ atitis. The corneal infiltrate may show irregular margins.


**Table 2.** Signs and symptoms of keratitis caused by mycobacterias
