Bacteriophage treatment of disseminated cutaneous Mycobacterium chelonae infection

Abstract

Mycobacterium chelonae is a rare cause of chronic disseminated cutaneous infections in immunocompromised patients. Multidrug-resistant M. chelonae infections present a challenge for treatment, and prolonged antimicrobial courses lead to significant toxicities and further antimicrobial resistance. We report a case of refractory cutaneous disseminated M. chelonae infection in a patient with seronegative arthritis on immunotherapy with tofacitinib that was treated with combination antimicrobial, surgical, and single bacteriophage therapy with excellent clinical response. The patient developed neutralizing antibodies against the bacteriophage but continues to have stable improvement of disease with negative biopsies and no evidence of bacterial resistance to the phage.

Fig. 1. Clinical course of M. chelonae infection.

A Left upper extremity with multiple large erythematous, fluctuant to nodular lesions ultimately diagnosed as disseminated cutaneous Mycobacterium chelonae infection. B Images of the left upper extremity lesions prior to (Dec 2020) and following (August 2021) addition of bacteriophage therapy. C PET/CT prior to (March 2021) and following (August 2021) addition of bacteriophage therapy.

Fig. 2. Treatment of M. chelonae infection.

Timeline of antimicrobial and bacteriophage administration for M. chelonae infection from January 2020 to December 2021.

Fig. 3. Bacteriophages for therapy of M. chelonae.

A Ten-fold serial dilutions of each phage (left) were spotted onto top agar overlays of M. smegmatis mc²155 and M. chelonae GD153. Phages: 1, BPs∆33HTH_HRM10; 2, BPs∆33HTH_HRM^GD03; 3, Muddy; 4, Muddy_HRM^GD04; 5, Itos; 6, Adephagia∆41∆43; 7, ZoeJ∆45; 8, Fionnbharth∆45∆47; 9, Elmo_HRM^mc2155; 10, Isca_cpm; 11, Fred313cpm_∆33; 12, CrimD∆41-43; 13- BPs∆33HTH_HRM10_REM1; 14, Faith1∆38-40; 15, Faith1∆38-40_HRM^GD69; 16, MissWhite; 17, MissWhite-D29_Hybrid1, 18, Maco6; 19, TM4; 20, Wildcat; 21, D29; and 22, D29_HRM^GD40. B As for panel A but using M. abscessus lytically induced prophages plated on M. chelonae GD153 and control strain M. abscessus GD40. Phages: 1, phiGD20-1; 2, phiGD22-1; 3, phiGD23-1; 4, phiGD21-1; 5, phiGD34-2; 6, phiGD89-1; 7, phiGD57-1; 8, phiGD17-1; 9, phiGD24-3. C Killing of M. chelonae GD153 by Muddy following infection in liquid culture (moi, 10); -Muddy, no phage control. D Efficient killing of M. chelonae GD153 over ranges of bacterial and phage concentrations. All rows contain 10-fold serial dilutions of bacterial culture. Top row (–), no phage control; rows 2-9, 10-fold serial diltions, with 10¹⁰ PFU in row 2. E ELISA responses for anti-Muddy IgG antibodies in sera from 3 days, 17 days or 16 weeks after phage treatment initiation. Negative controls (ctrl) for uncoated wells are also shown. n = 2 technical replicates are shown. Data points are the average of two independent sets of serum dilutions and measurements, with error bars ± one standard deviation. F Half-maximal IgG titers derived from ELISA curve fits in panel D. Duplicate measurements are shown as points; bar height is the mean titer with error bars±one standard deviation. Source data for panels E and F are provided as a Source Data file. G To test for antibody neutralization, Muddy was incubated with either plasma (p) or serum (s) from 2 days, 3 days, 17 days or 16 weeks after the start of phage administration for 2 h (top) or 24 h (bottom) and then 10-fold serial dilutions were spotted onto top agar overlays of M. smegmatis mc²155. Plates were incubated at 37 °C for 48 h.