Nontuberculous Mycobacterial Keratitis

Abstract

Addi"ional informa"ion is available a" "he end of "he chap"er h""p://dx.doi.org/10.5772/45964 . IntroductionMycobacterium species that are considered typical are the tuberculosis species such as M.tuberculosis, M.bovis, M.africarium and M.leprae. These species have only human or animal reservoirs and are not transmitted by water. In contrast, the species Non-Tuberculosis or atypical , naturally are ubiquitous in soil and water and have been found as normal flora of skin, sputum, and gastric contents. These bacteria are resistant to common, disinfectants, chlorine, formaldehyde and glutaraldehyde.NTM can cause infections on all adnexal and ocular tissues including the cornea, iris, lens, retina, choroid and optic nerve. Most NTM infections are caused by M.chelonae and M. fortuitum, that as we will discuss later, belong to the rapid growers group.In this chapter, we will focus on keratitis caused by atypical mycobacterium, since a great number of recent clinical reports of NTM ocular infections are of keratitis. In common general ophthalmology procedures like refractive surgery, for example laser in situ keratomileusis L"SIK , Laser epithelial keratomileusis L"SEK , photorefractive keratectomy PRK , and other specialized procedures such as penetrating keratoplasty PKP , a transgression to natural barriers occurs, this constitutes a risk factor for infection by these organisms. In addition, L"SIK is one of the most commonly performed procedures in ophthalmology practice.Several factors may contribute to the development of mycobacterial keratitis following L"-SIK, making it difficult to determine the true origin of the infection in most cases. This procedure is often performed utilizing aseptic, but non sterile techniques. Mycobacterium © 2013 Pérez-Balb"ena e" al.; licensee InTech. This is an open access ar"icle dis"rib""ed "nder "he "erms of "he Crea"ive Commons A""rib""ion License (h""p://crea"ivecommons.org/licenses/by/3.0), which permi"s "nres"ric"ed "se, dis"rib""ion, and reprod"c"ion in any medi"m, provided "he original work is properly ci"ed. chelonei, M. abscessus, M. fortuitum, M. szulgai, and M. mucogenicum have been reported as the result of improper asepsis."typical Mycobacteria corneal infections are rare, but devastating complications. "lthough rare, are a diagnostic and therapeutic challenge. Mycobacterium have been involved in several isolated cases as well as in outbreaks. [ -] . Microbiological and laboratory profileMycobacterium species that are considered typical are the tuberculosis specie M.tuberculosis. Many species enclosed in genus Mycobacteriaceae are true human pathogens as Mycobacterium tuberculosis complex, that include M tuberculosis, M bovis, non pathogenic M bovis "CG, M africanum, M caprae, M microti, and M pinnipedii are characterized by different phenotypes and mammalian host ranges, displays the most extreme genetic homogeneity with . to . % nucleotides variation only. Growth rate in this group is to weeks. M leprae is the only non cultivable in vitro specie and has some genet...