https://orcid.org/0000-0003-1957-2925
Figures & data
Figure 1. World map showing the distribution of trachoma and Buruli ulcer (BU). Countries colored in red have reported cases of Buruli ulcer in the year 2018. Countries colored in blue have reported trachoma cases in the year 2019 and are still considered to require intervention programs to eliminate trachoma. The purple color represents the overlap of required trachoma elimination and reported BU cases.
Figure 2. Effect of temperature pulses of 37 °C (A) or 42 °C (B) or permanent exposure to 30°C (C) on the metabolic activity of M. ulcerans. Cultures of the three freshly isolated [Citation49] Cameroonian M. ulcerans strains S1012 (black bars), S1013 (empty bars), and S1047 (grey bars) were grown in Difco Middlebrook 7H9 medium (BD), supplemented with 10% (vol/vol) Middlebrook OADC enrichment medium (BD) and 0.2% (vol/vol) glycerol at 30 °C in triplicate in microtiter plates. The bacterial cultures were treated for 5 days with one temperature pulse of 20 min, one hour or three hours per day. After 2 days of recovery at 30 °C, a resazurin microtiter assay adapted for the extremely slow-growing M. ulcerans [Citation50] was used to determine the metabolic activity of the bacteria. After the addition of 10% (vol/vol) of a resazurin solution (0.125 mg/mL, Sigma) to the cultures and incubation for another 3 days at 30 °C, end-point fluorescence reading (Ex540nm/Em588nm) was performed. Values represent means of fluorescent units ± SD.
![Figure 2. Effect of temperature pulses of 37 °C (A) or 42 °C (B) or permanent exposure to 30°C (C) on the metabolic activity of M. ulcerans. Cultures of the three freshly isolated [Citation49] Cameroonian M. ulcerans strains S1012 (black bars), S1013 (empty bars), and S1047 (grey bars) were grown in Difco Middlebrook 7H9 medium (BD), supplemented with 10% (vol/vol) Middlebrook OADC enrichment medium (BD) and 0.2% (vol/vol) glycerol at 30 °C in triplicate in microtiter plates. The bacterial cultures were treated for 5 days with one temperature pulse of 20 min, one hour or three hours per day. After 2 days of recovery at 30 °C, a resazurin microtiter assay adapted for the extremely slow-growing M. ulcerans [Citation50] was used to determine the metabolic activity of the bacteria. After the addition of 10% (vol/vol) of a resazurin solution (0.125 mg/mL, Sigma) to the cultures and incubation for another 3 days at 30 °C, end-point fluorescence reading (Ex540nm/Em588nm) was performed. Values represent means of fluorescent units ± SD.](/cms/asset/1da920fe-c19d-4d5f-bf7c-ab89feec91e6/ihyt_a_1751312_f0002_b.jpg)
Figure 3. Effects of five daily temperature pulses of 20 min or 3 h at 42 °C on the viability of M. ulcerans (shown by the mean number of colony-forming units, (CFUs) ± SD for the three tested strains). Liquid cultures of the three freshly isolated Cameroonian M. ulcerans strains S1012, S1013, and S1047 grown at 30 °C in Difco Middlebrook 7H9 medium (BD), supplemented with 10% (vol/vol) Middlebrook OADC enrichment medium (BD) and 0.2% (vol/vol) glycerol were exposed to temperature pulses at 42 °C on five consecutive days, then serially diluted and plated on Difco Middlebrook 7H10 agar plates (BD), supplemented with 10% (vol/vol) Middlebrook OADC enrichment medium (BD) and 0.2% (vol/vol) glycerol. The number of CFUs was determined after four months of incubation of the extremely slow growing bacilli at 30 °C. In addition, CFU counts of cultures incubated for 5 days at 37 °C or 42 °C were compared with a control remaining at 30 °C.
Figure 4. Developmental cycle of Chlamydia including the extracellular, infectious elementary body (EB), the intracellular replicating reticulate body (RB) and the persistent aberrant body (AB) induced by stress conditions. wIRA treatment at different timepoints of the developmental cycle has shown reductive effects on chlamydial infectivity.
