The persistent dilemma of microbial keratitis: Global burden, diagnosis, and antimicrobial resistance

Abstract

Microbial keratitis is a potentially blinding condition that must be treated emergently to preserve vision. Although long recognized as a significant cause of corneal blindness, our understanding of its true global scale, associated burden of disease, and etiological patterns remains somewhat limited. Current epidemiological data suggest that microbial keratitis may be epidemic in parts of the world-particularly within South, SouthEast , and East Asia-and may exceed 2 million cases per year worldwide. Etiological patterns vary between economically developed and developing countries, with bacterial predominance in the former and fungal predominance in the latter. The key to effective management lies in timely diagnosis; however, the current gold standard of stain and culture remains time consuming and often yields no clinically useful results. For this reason, there are attempts to develop highly sensitive and accurate molecular diagnostic tools to provide rapid diagnosis, inform treatment decision making, and minimize the threat of antimicrobial resistance. We provide an overview of these key areas and of avenues for further research toward the goal of more effectively addressing the problem of microbial keratitis on both an individual and public health level.

Characterization of Ocular Clinical Isolates of Pseudomonas aeruginosa from Non-Contact Lens Related Keratitis Patients from South India

“…P. aeruginosa adheres to the cell surface and releases toxins that result in recruitment of inflammatory cells leading to corneal scarring [2,3] that may lead to perforation of the cornea within 48-96 h of infection [4]. Contact lens wearers are at a higher risk of developing keratitis in developed Microorganisms 2020, 8, 260; doi:10.3390/microorganisms8020260 www.mdpi.com/journal/microorganisms countries, while ocular trauma and injury are the major risk factors in developing countries [5]. P. aeruginosa also causes acute or chronic infections in patients with cystic fibrosis, cancer or extensive burns [6].…”

<p>Treatment-Resistant Bacterial Keratitis: Challenges and Solutions</p>

“…The increase in microbial keratitis in developed countries has been linked to the widespread use of contact lenses. 7 The rate of microbial keratitis is much higher in developing countries, where access to health services is limited and risky occupations such as farming, and agriculture are more prevalent. Microbial keratitis has been reported at rates of 113 per 100,000 in Madurai 8 (Tamil Nadu, India) and 799 per 100,000 in Nepal.…”

“…Microbial keratitis has been reported at rates of 113 per 100,000 in Madurai 8 (Tamil Nadu, India) and 799 per 100,000 in Nepal. 9 A review by Ung et al 7 who conducted an etiological study including the three most extensive studies of each continent, points to a very important conclusion about the etiology of microbial keratitis. In all of the 15 studies representing North America, South America, Europe, the Middle East and Africa, Europe, and Oceania, most cases of microbial keratitis were bacterial in origin, whereas fungal cases outnumbered bacterial cases in four of the six studies representing South Asia and East Asia.…”

“…The most common pathogens associated with bacterial keratitis are Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae, and Pseudomonas aeruginosa. 2,7 However, these agents are not capable of causing infection in a healthy cornea. A healthy corneal epithelium is a protective barrier against bacterial infections, with the exception of a few bacterial species such as Neisseria, Corynebacterium, Haemophilus, and Listeria species.…”

Infectious Keratitis: The Great Enemy

“…This trend will continue beyond Visual Impairment and Blindness -What We Know and What We Have to Know 2 2020 [7] and will inevitably impact the eye care need in the near future. In the developed countries, infectious keratitis is usually associated with contact lens wear, but in developing countries, it is commonly caused by trauma during agricultural work [8][9][10][11][12][13][14][15][16][17]. Infectious keratitis is characterized by a corneal epithelial defect with underlying stromal inflammation caused by replicating microorganisms [14].…”