Table 1 Bacterial strains and eukaryotic cell lines used in this study

C. diphtheriae

DSM43988

non-toxigenic, isolated from throat culture

DSMZ, Braunschweig, Germany

DSM43989

tox⁺, unknown source

DSMZ, Braunschweig, Germany

DSM44123

non-toxigenic isolate, type-strain, unknown source

DSMZ, Braunschweig, Germany

ISS3319

C. diphtheriae var. mitis, non-toxigenic, isolated from patients affected by pharyngitis/tonsilitis

[1]

ISS4060

C. diphtheriae var. gravis, non-toxigenic, isolated from patients affected by pharyngitis/tonsilitis

[1]

ISS4746

C. diphtheriae var. gravis, non-toxigenic, isolated from patients affected by pharyngitis/tonsilitis

[21]

ISS4749

C. diphtheriae var. gravis, non-toxigenic, isolated from patients affected by pharyngitis/tonsilitis

[21]

NCTC13129

C. diphtheriae var. gravis, non-toxigenic, isolated from pharyngeal membrane, patient with clinical diphtheria

[2]

E. coli

DH5αMCR

endA1 supE44 thi-1 λ^- recA1 gyrA96 relA1 deoR Δ(lacZYA-argF) U196 ϕ80ΔlacZ ΔM15mcrA Δ(mmr hsdRMSmcrBC)

[9]

Salmonella enterica serovar Typhimurium ( S . Typhimurium)

NCTC12023

wild type identical to ATCC14028

NCTC, Colindale, UK

Cell lines

Detroit562

human hypopharyngeal carcinoma cells

[20]