Inhalation of airborne antibiotic resistance genes (ARGs) can lead to antimicrobial resistance and potential health risk. In modern society, increasing individuals stay more indoors, however, studies regarding the exposure to airborne ARGs in indoor environments and the associated risks remain limited. Here, we compared the variance of aerosol-associated ARGs, bacterial microbiomes, and their daily intake (DI) burden in dormitory, office, and outdoor environments in a university in Tianjin. The results indicated that compared to outdoor aerosols, indoors exhibited significantly higher absolute abundance of both ARG subtypes and mobile genetic elements (MGEs) (1–7 orders of magnitude), 16S rRNA genes (2–3 orders), and total culturable bacteria (1–3 orders). Furthermore, we observed that significantly different airborne bacterial communities are the major drivers contributing to the variance of aerosol-associated ARGs in indoor and outdoor aerosols. Notably, the high abundances of total bacteria, potential pathogenic genera, and ARGs (particularly those harbored by pathogens) in indoor and outdoor aerosols, especially in indoors, may pose an increased exposure risk via inhalation. The successful isolation of human pathogens such as Elizabethkingia anopheles, Klebsiella pneumonia, and Delftia lacustris resistant to the “last-resort” antibiotics carbapenems and polymyxin B from indoor aerosols further indicated an increased exposure risk in indoors. Together, this study highlights the potential risks associated with ARGs and their inhalation to human health in indoor environments.

The mosquito vectors of the genera Aedes and Anopheles present resistance to several commercial insecticides, which are also toxic to non-predator targets. On the other hand, essential oils are a promising source of insecticides. Thus, in this work, the essential oil from the leaves of Piper purusanum was characterized by gas chromatography–based approaches and evaluated as biodefensive against malaria and dengue vectors. The main compounds of P. purusanum essential oil were β-caryophyllene (57.05%), α-humulene (14.50%), and germacrene D (8.20%). The essential oil inhibited egg hatching (7.6 ± 1.5 to 95.6 ± 4.5%), caused larval death (LC₅₀ from 49.84 to 51.60 ppm), and inhibited the action of acetylcholinesterase (IC₅₀ of 2.29 µg/mL), which can be related to the mechanisms of action. On the other hand, the biological activities of β-caryophyllene, α-humulene, and germacrene D were higher than that of essential oil. In addition, these sesquiterpenes and essential oil did not show a lethal effect on Toxorhynchites splendens, Anisops bouvieri, Gambusia affinis, and Diplonychus indicus (LC₅₀ from 2098.80 to 7707.13 ppm), although D. indicus is more sensitive (SI/PSF from 48.56 to 252.02 ppm) to essential oil, representing a natural alternative against these relevant vectors.

In mosquito control programs, insecticides of botanical origin have the potential to eliminate eggs, larvae, and adults. So, the larvicidal, ovicidal, and oviposition-deterrent activities of petroleum ether and ethyl acetate extracts of the leaves of Eugenia jambolana, Solidago canadensis, Euodia ridleyi, and Spilanthes mauritiana were assayed against the three vector mosquito species, namely Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus. The larval bioassay was conducted following the World Health Organization method. The maximum larval mortality was found with ethyl acetate extract of S. mauritiana against the larvae of A. stephensi, A. aegypti, and C. quinquefasciatus with LC₅₀values of 11.51, 28.1, 14.10 ppm, respectively. The mean percent hatchability of the ovicidal activity was observed at 48-h post-treatment. The percent hatchability was found to be inversely proportional to the concentration of the extract and directly proportional to the number of eggs. The flower head extract of S. mauritiana gave 100 % mortality followed by E. ridleyi, S. canadensis, and E. jambolana against the eggs of the three mosquito vectors. For oviposition-deterrent effect, out of the five concentrations tested (20, 40, 60, 80, and 100 ppm), the concentration of 100 ppm showed a significant egg laying-deterrent capacity. The oviposition activity index value of E. jambolana, E. ridleyi, S. canadensis, and S. mauritiana against A. aegypti, A. stephensi, C. quinquefasciatus at 100 ppm were −0.71, −0.71, −0.90, −0.93, −0.85, −0.91, −1, −1, −0.71, −0.85, −1, and −1, respectively. These results suggest that the leaf/flower extracts of certain local plants have the potential to be developed as possible eco-friendly means for the control of mosquitoes.