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Tantalo LC, Lieberman NAP, Pérez-Mañá C, Suñer C, Vall Mayans M, Ubals M, González-Beiras C, Rodríguez-Gascón A, Canut A, González-Candelas F, Mueller J, Tapia K, Greninger AL, Giacani L, Mitjà O. Antimicrobial susceptibility of Treponema pallidum subspecies pallidum: an in-vitro study. THE LANCET. MICROBE 2023; 4:e994-e1004. [PMID: 37827185 PMCID: PMC10686905 DOI: 10.1016/s2666-5247(23)00219-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 07/08/2023] [Accepted: 07/13/2023] [Indexed: 10/14/2023]
Abstract
BACKGROUND The increasing incidence of syphilis and the limitations of first-line treatment with penicillin, particularly in neurosyphilis, neonatal syphilis, and pregnancy, highlight the need to expand the therapeutic repertoire for effective management of this disease. We assessed the in-vitro efficacy of 18 antibiotics from several classes on Treponema pallidum subspecies pallidum (T pallidum), the syphilis bacteria. METHODS Using the in-vitro culture system for T pallidum, we exposed the pathogen to a concentration range of each tested antibiotic. After a 7-day incubation, the treponemal burden was evaluated by quantitative PCR targeting the T pallidum tp0574 gene. The primary outcome was the minimum inhibitory concentration (MIC) at which the quantitative PCR values were not significantly higher than the inoculum wells. We also investigated the susceptibility of macrolide-resistant strains to high concentrations of azithromycin, and the possibility of developing resistance to linezolid, a proposed candidate for syphilis treatment. FINDINGS Amoxicillin, ceftriaxone, several oral cephalosporins, tedizolid, and dalbavancin exhibited anti-treponemal activity at concentrations achievable in human plasma following regular dosing regimens. The experiments revealed a MIC for amoxicillin at 0·02 mg/L, ceftriaxone at 0·0025 mg/L, cephalexin at 0·25 mg/L, cefetamet and cefixime at 0·0313 mg/L, cefuroxime at 0·0156 mg/L, tedizolid at 0·0625 mg/L, spectinomycin at 0·1 mg/L, and dalbavancin at 0·125 mg/L. The MIC for zoliflodacin and balofloxacin was 2 mg/L. Ertapenem, isoniazid, pyrazinamide, and metronidazole had either a poor or no effect. Azithromycin concentrations up to 2 mg/L (64 times the MIC) were ineffective against strains carrying mutations associated to macrolide resistance. Exposure to subtherapeutic doses of linezolid for 10 weeks did not induce phenotypic or genotypic resistance. INTERPRETATION Cephalosporins and oxazolidinones are potential candidates for expanding the current therapeutic repertoire for syphilis. Our findings warrant testing efficacy in animal models and, if successful, clinical assessment of efficacy. FUNDING European Research Council.
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Affiliation(s)
- Lauren C Tantalo
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, WA, USA
| | - Nicole A P Lieberman
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA
| | - Clara Pérez-Mañá
- Clinical Pharmacology Unit, Hospital Universitari Germans Trias i Pujol, Institut de Recerca Germans Trias i Pujol, Badalona, Spain; Department of Pharmacology, Therapeutics and Toxicology, Universitat Autònoma de Barcelona, Barcelona, Spain
| | - Clara Suñer
- Sexually Transmitted Infections and Skin Neglected Tropical Diseases Section, Fight Infectious Diseases Foundation, Hospital Germans Trias i Pujol, Barcelona, Spain; Universitat de Vic-Universitat Central de Catalunya, Vic, Spain
| | - Marti Vall Mayans
- Sexually Transmitted Infections and Skin Neglected Tropical Diseases Section, Fight Infectious Diseases Foundation, Hospital Germans Trias i Pujol, Barcelona, Spain
| | - Maria Ubals
- Sexually Transmitted Infections and Skin Neglected Tropical Diseases Section, Fight Infectious Diseases Foundation, Hospital Germans Trias i Pujol, Barcelona, Spain
| | - Camila González-Beiras
- Sexually Transmitted Infections and Skin Neglected Tropical Diseases Section, Fight Infectious Diseases Foundation, Hospital Germans Trias i Pujol, Barcelona, Spain
| | - Alicia Rodríguez-Gascón
- Pharmacokinetic, Nanotechnology, and Gene Therapy Group (PharmaNanoGene), Faculty of Pharmacy, University of the Basque Country UPV/EHU, Vitoria-Gasteiz, Spain; Bioaraba, Microbiology, Infectious Disease, Antimicrobial Agents, and Gene Therapy Group, Vitoria-Gasteiz, Spain
| | - Andrés Canut
- Bioaraba, Microbiology, Infectious Disease, Antimicrobial Agents, and Gene Therapy Group, Vitoria-Gasteiz, Spain; Microbiology Service, Araba University Hospital, Osakidetza Basque Health Service, Vitoria-Gasteiz, Spain
| | - Fernando González-Candelas
- Joint Research Unit Infection and Public Health, FISABIO-Universitat de València, València, Spain; Institute for Integrative Systems Biology, Universitat de València-CSIC, Paterna, Spain; CIBER Epidemiology and Public Health, Madrid, Spain
| | - John Mueller
- Innoviva Specialty Therapeutics, Waltham, MA, USA
| | - Kenneth Tapia
- Department of Medicine, Division of Allergy and Infectious Diseases, and Department of Global Health, University of Washington, Seattle, WA, USA
| | - Alexander L Greninger
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, USA; Vaccine and Infectious Disease Division, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Lorenzo Giacani
- Department of Medicine, Division of Allergy and Infectious Diseases, University of Washington, Seattle, WA, USA; Department of Medicine, Division of Allergy and Infectious Diseases, and Department of Global Health, University of Washington, Seattle, WA, USA.
| | - Oriol Mitjà
- Sexually Transmitted Infections and Skin Neglected Tropical Diseases Section, Fight Infectious Diseases Foundation, Hospital Germans Trias i Pujol, Barcelona, Spain; Universitat de Vic-Universitat Central de Catalunya, Vic, Spain; School of Medicine and Health Sciences, University of Papua New Guinea, Port Moresby, Papua New Guinea
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