# Evaluating and Managing the Microbial Contamination of Eye Drops: A Two-Phase Hospital-Based Study
## 4 Discussion
These sites (tip and cap) offer a broad surface exposed to commensal and environmental microorganisms that can transmigrate into the content of the eye drops and even come into direct contact with the ocular surface, eyelids, and eyelashes during medication administration, potentially leading to infection and the risk of ocular injury [18; 19; 20; 21; 23; 57; 58; 59; 60; 61; 62; 63]. Studies have shown that the rate of the eye dropper tip's direct contact with the ocular surface during drug administration ranges between 18% and 76% in different age groups, predominantly elderly [29; 30; 31; 32; 59; 64; 65; 66; 67; 68; 69; 70; 71; 72]. This investigation found that isolated microorganisms belonged to commensal and environmental flora. The human flora is usually nonharmful and even plays a protective role on the ocular surface [18; 40; 46; 48; 53; 73]. However, the proliferation of this flora, initially harmless, on the tip and the cap can represent a risk to the patient. The risk of ocular injury due to infection is high in individuals undergoing ocular surgery, wearing contact lenses long term, or using topical or systemic corticosteroids or immunosuppressive medications, in addition to those with lid deformities [9; 12; 14; 40; 47; 48; 50; 54]. The most frequently isolated bacteria documented as causative agents for ocular injury include _S. aureus_, _S. epidermidis_, and another _Staphylococcus_ spp., followed by _P. aeruginosa_[7; 7; 75]. Similarly, GPB were detected in this study on 90% of the tested dropper tips and caps. Other cultured microorganisms known to cause ocular diseases [76; 77; 78; 79; 80; 81; 82; 83; 84; 85; 86; 87] include _Corynebacterium_ spp., _Kcuria_ spp., _Bacillus_ spp., including _B. cereus_, _Lysinibucillus_ spp., _Roseomonas mucosa_, _Aerococcus viridans_, _Dolosigranulum pigrum_, _Pseudomonas oryzaehiabitans_, _Moraxella osmosis_, _Acinetobacter lwoffii_, _Stenotrophomonas maltophilia_, _Candida parapsilosis_, and _Microoccus luteus_. In the present investigation, _Candida_ spp. were detected in the residual content, on the dropper tip, and on the cap of only 1 eye drop bottle returned by a patient out of 110 collected bottles in phase 1. The literature review showed that numerous studies reported the microbial contamination of eye drop content with _Candida_ spp. [8]. These findings highlight the need for an effective antimicrobial technology incorporated into the dropper tip and cap. Therefore, the microbial contamination of eye drops is a complex multifactorial issue that may benefit from a bundle of complementary interventions [8]. These interventions encompass education and awareness for healthcare professionals and patients, clear instructions for use and the implications of hazardous behaviors given to patients, stringent preventive hygiene measures, and the use of a protective antimicrobial tip and cap [8]. The subsequent phase of the study examined the effectiveness of the integrated Pylote technology into the eye drop tip and cap. Pylote antimicrobial technology is a patented breakthrough innovation [88; 89] that can be integrated into numerous porous and non-porous surfaces without changing the manufacturing process [90]. The technology consists of mineral oxide microspheres that are non-metal, non-ionic, and non-nanoparticle-based. Pylote SAS technology is non-release, non-leaching, and friendly to humans. The mineral microspheres are high-purity ceramic particles, including zinc or magnesium oxides, manufactured via a one-step proprietary cleantech process called Pyrolyse PulveriseeTM[91]. ZnO and MgO are authorized additives for parenteral pharmaceutical containers according to the _European Pharmacopoeia_, _United States Pharmacopoeia_, and _Japanese Pharmacopoeia_[91]. The mechanism of action is not photo-activation and depends on microsphere surface defects called oxygen vacancies [92]. The mineral microspheres are electron donors that generate, when in contact with water or oxygen, reactive oxygen species (ROS), mainly hydroxyl radicals [93].