Emergence and Spread of Multidrug Resistance in Ocular Bacterial Pathogens: A Current Update

Abstract

The tremendous increase of multidrug-resistant bacterial pathogens has posed a serious threat in the management of infectious diseases. The human eye is known to commensally host the normal flora, including the opportunistic pathogens. The researchers have isolated and characterized numerous microbes belonging to different genera from healthy eye, including Pseudomonas, Propionibacterium, Acinetobacter, Corynebacterium, Brevundimonas, Staphylococcus, Sphyngomonas, Streptococcus, and many others. The human eye is virtually impermeable to microbes, despite being exposed to an array of microorganisms. Ocular infections usually occur through invasion of microbes that may come either from bloodstream or by breaching the ocular barriers. Both gram-negative and gram-positive bacteria are known to be responsible for ocular infections, with the major causative gram-positive bacteria being S. pneumoniae, coagulase-negative staphylococci, S. aureus, and S. pyogenes, with N. gonorrhoeae, Moraxella spp., P. aeruginosa, K. pneumoniae, E. coli, and Proteus spp. also being commonly isolated. Apart from the unchecked use of antibiotics and the dissemination of multidrug-resistant bacteria, development of biofilms on ocular surfaces are also a major concern for antimicrobial resistance. In biofilms, the antibiotics are less likely to penetrate, due to reduced rates of diffusions making some of the cells in biofilms more resistant, and eventually increasing the effective antibiotic dose by many folds in comparison to planktonic mode cells. In this chapter, a survey on the emergence and spread of MDR ocular bacterial pathogens has been made.