Proteus mirabilis Keratitis: Risk Factors, Clinical Features, Treatment Outcomes, and Microbiological Characteristics

Bacterial contamination of multi-use tear drops, gels, and ointments

PURPOSE

This study aimed to investigate the bacterial contamination of multi-use tear drops, gels, and ointments that patients use at home.

METHOD

A total of 271 multi-use containers used by 168 patients were examined. Conjunctival culture samples were obtained from patients who used tear drops, gels, and ointments that were found to be contaminated.

RESULTS

Bacterial contamination was detected in 33 (12.2 %) out of the 271 containers. The contamination rate was 7.9 % in tear drops, 11.7 % in gels, and 32 % in ointments. A statistically significant difference was found between the drops, gels, and ointment groups (P = 0.04). Bacterial contamination was detected in 25 (18.9 %) out of 132 collapsible tubes and 8 (5.8 %) out of 139 plastic bottles (P = 0.01). Important bacteria, including Pseudomonas stutzeri, Pseudomonas aeruginosa, Bacillus licheniformis, Paenibacillus pabuli, Proteus mirabilis, Pantoea agglomerans, Morganella morganii, Serratia marcescens, and Serratia liquefaciens, were detected. Mucorales spp. fungus was seen in a gel. Staphylococcus epidermidis, methicillin-resistant Staphylococcus aureus, and M. morganii were found in the conjunctival microbiota of three patients.

CONCLUSION

The overall contamination rate of ocular lubricants was low (12.2%); however, a significant difference was found between the drops, gels, and ointments. The contamination rate was higher in gels and ointments than that in drops. The contamination rate was found to be increased in the collapsible tube. The use of ocular lubricants is safe; however, patients must be cautious when using multi-use tear drops, gels, and ointments to avoid contamination. Whenever possible, bottles should be preferred instead of collapsible tubes.

Could the Urease of the Gut Bacterium Proteus mirabilis Play a Role in the Altered Gut-Brain Talk Associated with Parkinson's Disease?

Intestinal dysbiosis seems to play a role in neurodegenerative pathologies. Parkinson's disease (PD) patients have an altered gut microbiota. Moreover, mice treated orally with the gut microbe Proteus mirabilis developed Parkinson's-like symptoms. Here, the possible involvement of P. mirabilis urease (PMU) and its B subunit (PmUreβ) in the pathogenesis of PD was assessed. Purified proteins were given to mice intraperitoneally (20 μg/animal/day) for one week. Behavioral tests were conducted, and brain homogenates of the treated animals were subjected to immunoassays. After treatment with PMU, the levels of TNF-α and IL-1β were measured in Caco2 cells and cellular permeability was assayed in Hek 293. The proteins were incubated in vitro with α-synuclein and examined via transmission electron microscopy. Our results showed that PMU treatment induced depressive-like behavior in mice. No motor deficits were observed. The brain homogenates had an increased content of caspase-9, while the levels of α-synuclein and tyrosine hydroxylase decreased. PMU increased the pro-inflammatory cytokines and altered the cellular permeability in cultured cells. The urease, but not the PmUreβ, altered the morphology of α-synuclein aggregates in vitro, forming fragmented aggregates. We concluded that PMU promotes pro-inflammatory effects in cultured cells. In vivo, PMU induces neuroinflammation and a depressive-like phenotype compatible with the first stages of PD development.

Ocular Bacterial Infections: A Ten-Year Survey and Review of Causative Organisms Based on the Oklahoma Experience

Ocular infections can be medical emergencies that result in permanent visual impairment or blindness and loss of quality of life. Bacteria are a major cause of ocular infections. Effective treatment of ocular infections requires knowledge of which bacteria are the likely cause of the infection. This survey of ocular bacterial isolates and review of ocular pathogens is based on a survey of a collection of isolates banked over a ten-year span at the Dean McGee Eye Institute in Oklahoma. These findings illustrate the diversity of bacteria isolated from the eye, ranging from common species to rare and unique species. At all sampled sites, staphylococci were the predominant bacteria isolated. Pseudomonads were the most common Gram-negative bacterial isolate, except in vitreous, where Serratia was the most common Gram-negative bacterial isolate. Here, we discuss the range of ocular infections that these species have been documented to cause and treatment options for these infections. Although a highly diverse spectrum of species has been isolated from the eye, the majority of infections are caused by Gram-positive species, and in most infections, empiric treatments are effective.

Paradox of complex diversity: Challenges in the diagnosis and management of bacterial keratitis

Bacterial keratitis continues to be one of the leading causes of corneal blindness in the developed as well as the developing world, despite swift progress since the dawn of the "anti-biotic era". Although, we are expeditiously developing our understanding about the different causative organisms and associated pathology leading to keratitis, extensive gaps in knowledge continue to dampen the efforts for early and accurate diagnosis, and management in these patients, resulting in poor clinical outcomes. The ability of the causative bacteria to subdue the therapeutic challenge stems from their large genome encoding complex regulatory networks, variety of unique virulence factors, and rapid secretion of tissue damaging proteases and toxins. In this review article, we have provided an overview of the established classical diagnostic techniques and therapeutics for keratitis caused by various bacteria. We have extensively reported our recent in-roads through novel tools for accurate diagnosis of mono- and poly-bacterial corneal infections. Furthermore, we outlined the recent progress by our group and others in understanding the sub-cellular genomic changes that lead to antibiotic resistance in these organisms. Finally, we discussed in detail, the novel therapies and drug delivery systems in development for the efficacious management of bacterial keratitis.