Antimicrobial Susceptibility Patterns and Resistance Trends of Staphylococcus aureus and Coagulase-Negative Staphylococci Strains Isolated from Ocular Infections.

Francesco Petrillo,Michele Rinaldi,Maria Teresa Della Rocca,Niccolò Castellino,Marilena Galdiero,Federica Maria Di Lella,Veronica Folliero,Danilo Pignataro,Teresio Avitabile,Giovanni Boccia,Guglielmo Parisi,Michele D’Amico,Gianluigi Franci,Michele Reibaldi,Biagio Santella,Maria Consiglia Trotta,Matteo Fallico

doi:10.3390/antibiotics10050527

Abstract

Ocular bacterial infections represent a serious problem that affecting people of all age and genders. These infections can lead to visual impairment and blindness if not properly treated. The current study evaluates the antimicrobial resistance profiles and the resistance trend of both Staphylococcus aureus (S. aureus) and coagulase-negative staphylococci (CoNS), the main pathogens involved in eye infections. A total of 322 isolates of S. aureus and CoNS, were collected from patients with bacterial conjunctivitis and keratitis at the “Luigi Vanvitelli” University Hospital of Campania in Naples, Italy, between 2017 and 2020. The isolated bacteria showed a high percentage of resistance to methicillin and other antibiotics commonly used for the treatment of ocular infections. Trends in antibiotic resistance were not encouraging, recording—especially among CoNS strains—an increase of more than 20% in resistance to methicillin and aminoglycosides during the study period. Instead, the resistance rates to tetracycline had a significant decrease in CoNS isolates while no changes in their susceptibility to fluoroquinolones and macrolides were observed. However, all isolates showed no resistance to trimethoprim/sulfamethoxazole and chloramphenicol. In this scenario, preventive identification of the infection causative agents and the evaluation of the antimicrobial susceptibility patterns are essential to set up an ocular infection effective drug treatment and also prevent antibiotic resistance.

Highlights

The ocular surface is invariably exposed to a wide range of microorganisms, the eye is generally impermeable to almost all potentially infectious external agents, relying on a large number of natural defense mechanisms, such as the presence of a commensal 4.0/).microbial flora—capable of preventing the engraftment of pathogenic microorganisms—and the tear film—containing agents such as lactoferrin, defensins and lysozyme, with high antimicrobial power [1]
322 non-repetitive Staphylococcus strains were isolated from patients with bacterial conjunctivitis and keratitis clinically diagnosed and laboratory confirmed at the “Luigi Vanvitelli” University Hospital of Campania in Naples, Italy
Given the high percentage of eye infections caused by S. aureus and coagulase-negative staphylococci (CoNS) and the increasing resistance to various antibacterial agents shown by these pathogenic microorganisms, the current analysis aims to evaluate the antibiotic susceptibility patterns, the resistance rates and the trend of these Gram-positive bacteria isolated from patients with eye infections

Summary

Introduction

The ocular surface is invariably exposed to a wide range of microorganisms, the eye is generally impermeable to almost all potentially infectious external agents, relying on a large number of natural defense mechanisms, such as the presence of a commensal 4.0/).microbial flora—capable of preventing the engraftment of pathogenic microorganisms—and the tear film—containing agents such as lactoferrin, defensins and lysozyme, with high antimicrobial power [1]. As reported in several studies, the most common bacteria involved in ocular infections are Staphylococcus aureus (S. aureus), Coagulase-negative staphylococci (CoNS), Streptococcus pneumoniae, Corynebacterium spp., Bacillus spp., Nocardia, Pseudomonas aeruginosa, Haemophilus influenzae and Enterobacteriaceae [8]. Among these bacteria, S. aureus and CoNS strains are very important for their high prevalence of infection, while S. aureus is among the most common cause of blepharitis, conjunctivitis, dacryocystitis, keratitis and endophthalmitis.

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