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Environmental Effects Triggering Antibiotic Resistance in Bacteria
BROOKE SMITH, Maria King, Texas A&M University
Abstract Number: 120
Working Group: Bioaerosols
Abstract
Antibiotic resistance is a threat globally to public health, safety and agriculture. Recent research has found that bioaerosols change physically, chemically and biologically in different environmental conditions. The goal of this research was to explore how gram-negative and gram-positive bacteria react to different environmental conditions, including temperature, relative humidity, airflow and duration of aerosolization. Fresh vegetative Escherichia coli (E. coli) cells and Bacillus globigii (B. globigii) spores were aerosolized at different durations and collected using a 100 L/min wetted wall cyclone (WWC) bioaerosol collector and a 300 L/min low-cutpoint WWC collector. The response of each bioaerosol to environmental conditions was analyzed by susceptibility and genetic testing. The Kirby Bauer susceptibility test indicated the strongest resistance response to cephalothin, gentamicin, and ciprofloxacin, which are cell wall or DNA replication inhibitors respectively. Significantly more resistance was detected in E. coli aerosolized for 5 min versus 45 min, however, similar resistance was detected in the 5 minute and 30 min aerosolizations which indicated that aerosolization over 30 min causes increased amount of stress that the bacteria cannot alleviate. Interestingly, no resistance was detected in bacteria aerosolized for 10 min, potentially due to a transient response of the cells to compensate for the osmotic and other stresses during aerosolization. However, high susceptibility was maintained in all durations to imipenem and cefoperazone, both cell wall synthesis inhibitors, albeit with a contrasting mechanism to other beta lactams. The culturability of archived spores increased significantly compared to E. coli aerosols. Fresh E. coli collected with the low-cutpoint sampler exhibited a dormant duration of viability but recovered after 2 days at room temperature. The knowledge gained from this study may help in designing environmental conditions to attenuate the development of ARGs and antibiotic resistance in bioaerosols.