Sterility Assessment of Some Face Masks for Public Use During COVID-19 Pandemic in Lagos, Nigeria

Abstract

Globally, the use of face masks is one of the non-pharmaceutical interventions recommended as a method of preventing spread of SARS-CoV-2. Lagos State was an epicenter of COVID-19 and as such, the State Government made the use of facemasks mandatory while in the public and social gatherings. Due to the alarming rate of spread of COVID-19 pandemic, shortage of masks and respirators has been observed and reported globally. This has led to production and use of different types of facemasks including locally made facemasks of different fabrics. A total of 400 consisting of 200 made of local fabrics, 100 imported face/surgical masks and 100 N95 respirators were selected from different sources in Lagos State between May 2020 and November 2020. Samples were immersed aseptically into conical flask containing 100ml Nutrient broth and incubated 18-24hrs. The broth culture was sub-cultured onto Sabouroid Dextrose Agar in duplicates. One of the SDA was incubated at room temperature and the other at 37°C. Blood, Chocolate and MacConkey agar plates were also inoculated and incubated at 37°C for 18-24 hrs. Isolates were identified using phenotypic identification methods. Of the total 400 samples, 346 (86.5%) had no bacterial or fungal growth while 44 (11.0%) had one bacterial isolate and 10 (2.5%) had mixed growth of bacterial isolates. Of the 200 locally-made face masks, 39 (19.5%) had one bacterial isolate and 9 (4.5%) had two bacterial isolates and 5 (2.5%) had fungal isolates while out of the 100 imported surgical masks, only 4 (4.0%) had one bacterial isolate and one (1.0%) had mixed growth of bacterial isolates. One (1.0%) of the imported N95 respirator had only one bacterial isolate <i>(Lactobacilli spp)</i>. Generally, the isolated bacteria were <i>Staphylococcus aureus, Coagulase negative Staphylococcus, Escherichia coli, Klebsiella species and Lactobacilli species while fungal isolates were Candida albicans and Aspergillus fumigatus</i>. The locally-made face masks were contaminated with both bacterial and fungal isolates. Face masks with no bacterial or fungal growth had a p-value of 0.02 and it is statistically significant in terms of the face masks tested in this study. Face masks with one bacterial isolate had a p value of 0.35 and those mixed growth of two different bacterial and fungal isolates had a p value of 0.36 which indicated a non-statistically significant results of the face mask tested in these categories. Locally made face masks were more contaminated with single or mixed bacterial and fungal agents. Cautionary use of the masks is recommended.