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Aztreonam-induced filamentation in Pseudomonas aeruginosa

Cite this dataset

Smith, Nicholas (2024). Aztreonam-induced filamentation in Pseudomonas aeruginosa [Dataset]. Dryad. https://doi.org/10.5061/dryad.1ns1rn907

Abstract

Objectives: The proliferation of metallo-beta-lactamase-producing Pseudomonas aeruginosa represents a significant public health threat. P. aeruginosa can undergo significant phenotypic changes that can drastically impair antibiotic efficacy. This study’s objectives were (1) to quantify the time course of killing of VIM-2-producing P. aeruginosa in response to aztreonam-based therapies, and (2) to document the capacity of P. aeruginosa to undergo morphological transformations that facilitate persistence.

Methods: A well-characterized, clinical VIM-2-producing P. aeruginosa was studied in the Hollow Fiber Infection Model (HFIM) over 9 days (7 days of active antibiotic therapy, 2 days treatment withdrawal) at a 107.5 CFU/mL starting inoculum. HFIM treatment arms included: growth control, aztreonam, ceftazidime/avibactam, aztreonam/‌ceftazidime/‌avibactam, polymyxin B, and aztreonam/‌ceftazidime/‌avibactam/‌polymyxin B. In addition, real-time imaging studies were conducted under static conditions to determine the time course of the reversion of persister cells. 

Results: A pronounced discrepancy was observed between OD620 and bacterial counts obtained from plating methods (hereafter referred to as ‘OD-count discrepancy’). For aztreonam monotherapy, observed counts were 0 CFU/mL by 120 h. Despite this, there was a significant OD-count discrepancy as compared to the pre-treatment 0h. Between therapy withdrawal at 168h and 216h, all arms with suppressed counts had re-grown to the system carrying capacity. Real-time imaging of the P. aeruginosa filaments after drug removal showed rapid reversion from a long, filamentous phenotype to many individual rods within 2 h.

Conclusion: Managing MBL-producing P. aeruginosa will require a multi-faceted approach, focused on maximizing killing and minimizing proliferation of resistant and persistent subpopulations, which will involve eliminating drug-induced phenotypic transformers.

README: Aztreonam-induced filamentation in Pseudomonas aeruginosa


Author: Nicholas M. Smith, PharmD, PhD
Contact: nmsmith2@buffalo.edu
Last Update: 2023-07-20

These videos were generated through timelapse microscopy of a clinical VIM-2-producing P. aeruginosa under selective pressure by aztreonam and after drug removal.

Description of the data file and structure

2020_20_31_782_Exponential Growth_MHB.wmv
2020_20_31_782_Filamentation_AZT_67.wmv
2020_20_31_782_Reversion_6hr.wmv
2020_20_31_782_Reversion_18hr.wmv
2020_20_31_782_Reversion_24hr.wmv
2020_20_31_782_Reversion_48hr.wmv

2020_20_31_782_Exponential Growth_MHB.wmv
-This timelapse video is of P. aeruginosa in exponential growing phase without drug pressure

2020_20_31_782_Filamentation_AZT_67.wmv
-This timelapse video is of P. aeruginosa in expoenntial growing phase under drug pressure (aztreonam 66mg/L, static conditions), which shows bacterial filamentation

2020_20_31_782_Reversion_6hr.wmv

  • This time-lapse video is of P. aeruginosa after gently washing drug off of cells after 6 hours of drug exposure. Filaments are shown to revert back to rod shapes then divide normally

2020_20_31_782_Reversion_18hr.wmv

  • This time-lapse video is of P. aeruginosa after gently washing drug off of cells after 18 hours of drug exposure. Filaments are shown to revert back to rod shapes then divide normally

2020_20_31_782_Reversion_24hr.wmv

  • This time-lapse video is of P. aeruginosa after gently washing drug off of cells after 24 hours of drug exposure. Filaments are shown to revert back to rod shapes then divide normally

2020_20_31_782_Reversion_48hr.wmv

  • This time-lapse video is of P. aeruginosa after gently washing drug off of cells after 48 hours of drug exposure. Filaments are shown to revert back to rod shapes then divide normally

Fig1_SEM_10k.7z
SEM Images for Figure 1 are also provided in full resolution with scale bars

Funding

National Institute of Allergy and Infectious Diseases, Award: R01AI165997

National Institute of Allergy and Infectious Diseases, Award: R01AI148560