Microbiota assessment in optical shops: an ignored concern to public health

The presence of microorganisms in ophthalmic instruments and surfaces can lead to the exposure of patients to several infections. However, there is no information regarding fungal and bacteria contamination in optical shops. This study aims to characterize fungi and bacteria contamination in air and surfaces from 10 optical shops covering also ophthalmic instruments. Air samples were collected through an impaction method onto malt extract agar (MEA) supplemented with chloramphenicol (0.05%) used for fungi and Tryptic Soy Agar (TSA) supplemented with nystatin (0.2%) used for bacteria. Outdoor samples were also performed to be used as reference. Surface and equipment’s swab samples were also collected side-by-side. All the collected samples were incubated at 27ºC for 5 to 7 days (fungi) or at 30º for 7 days (bacteria). Regarding fungal distribution, thirteen different species/genera were found in the air, being the most common Alternaria sp. (62.0%). Eight different species/genera were identified in the surfaces, ranging from 2 to 5x104 CFU/m2, being the most common A. versicolor complex and Penicillium sp. (40.0%). The trial frames were the most contaminated equipment, since 50.0% of the collected samples were with countless colonies. The airborne bacterial population indicated higher concentrations in the contactology office (average: 133 CFU/m3) than in the client’s waiting rooms (average: 126 CFU/m3). The surface samples indicated bacterial concentrations ranging from 2x104 to 1x106 CFU/m2, pointing out the automatic refractometer as the surface with higher bacterial load.

Gamma radiation effects on microbial inactivation of two medicinal plants

The consumption of natural products has become a public health problem, since these medicinal teas are prepared using natural plants without an effective hygienic and sanitary control. The aim of this study was to assess the effects of gamma radiation, on the microbial burden of two medicinal plants: Melissa officinalis and Lippia citriodora. Dried samples of the two plants were irradiated at a Co-60 experimental equipment. The applied gamma radiation doses were 1, 3, and 5 kGy at a dose rate of 1.34 kGy/h. Non-irradiated samples followed all the experiments. Bacterial and fungal counts were assessed before and after irradiation by membrane filtration method. Challenging tests with Escherichia coli were performed in order to evaluate the disinfection efficiency of gamma radiation treatment. Characterization of M. officinalis and L. citriadora microbiota indicated an average bioburden value of 102CFU/g. The inactivation studies of the bacterial mesophilic population of both dried plants pointed out to a one log reduction of microbial load after irradiation at 5 kGy. Regarding the fungal population, the initial load of 30 CFU/g was only reduced by 0.5 log by an irradiation dose of 5 kGy. The dynamics with radiation doses of plants microbial population’s phenotypes indicated the prevalence of gram-positive rods for M. officinalis before and after irradiation, and the increase of the frequency of gram-negative rods with irradiation for L. citriadora. Among fungal population of both plants, Mucor, Neoscytalidium, Aspergillus and Alternaria were the most isolated genera. The results obtained in the challenging tests with E. coli on plants pointed out to an inactivation efficiency of 99.5% and 99.9% to a dose of 2 kGy, for M.officinalis and L. citriadora, respectively. The gamma radiation treatment can be a significant tool for the microbial control in medicinal plants.