Penicillin tolerance amongst non-toxigenic Corynebacterium diphtheriae isolated from cases of pharyngitis

Abstract

Twenty-four strains of non-toxigenic Corynebacterium diphtheriae biotype gravis from the throats of patients with pharyngitis/tonsillitis were assayed for susceptibility to penicillin and erythromycin using determination of MIC, MBC and time-kill curves. There were no differences between the MICs of penicillin for susceptible and tolerant strains. All but one strain had penicillin MBCs > or = 2 mg/L. Seventy-one per cent (17/24) of the strains were tolerant to penicillin. In contrast, all strains were susceptible to erythromycin (MIC < or = 0.016 mg/L). These aspects should be considered when choosing the therapy for treating non-toxigenic C. diphtheriae pharyngitis/tonsillitis.

Molecular epidemiology and characteristics of Corynebacterium diphtheriae and Corynebacterium ulcerans strains isolated in Italy during the 1990s

“…The treatment failure could be related to the fact that the MBCs of penicillin for these non-toxigenic strains are high, often above the penicillin serum level of about 2-4 mg ml À1 (Chamber & Neu, 1995), and that the majority of C. diphtheriae isolates are tolerant to this antibiotic. Seventy one percent of sore throat isolates of non-toxigenic C. diphtheriae biotype gravis were recently reported to be tolerant to penicillin (von Hunolstein et al, 2002). It is therefore important to be aware that where C. diphtheriae is the only pathogen to be isolated from cases of pharyngitis/ tonsillitis, this organism could be the cause of that infection and that penicillin is not the most appropriate antibiotic.…”

Antimicrobial resistance among Brazilian Corynebacterium diphtheriae strains

“…However, resistance to penicillin G, oxacillin, erythromycin, and other drugs including rifampicin, tetracycline, and clindamycin used in therapy of C. diphtheriae infections have been reported (Formiga et al 1971, Rockhill et al 1982, Gruner et al 1992, Maple et al 1994, Patey et al 1995, Gladin et al 1999, Von Hunolstein et al 2002. Resistance to ß-lactams should also be considered in systemic infections, since failure to eliminate C. diphtheriae in cases of endocarditis treated with penicillin have been reported.…”

“…The procedures for susceptibility testing and the range of interpretative categories of susceptibility for each antimicrobial agent were similar to those recommended previously (Martínez-Martínez et al 1995, Funke et al 1996, Von Hunolstein et al 2002. Antimicrobial susceptibility assays were determined by using Mueller Hinton base supplemented with 5% sheep blood and inoculums of ~10 CFU\ml.…”

“…The presence of diphtheria bacilli resistant to drugs frequently used in the treatment of infections from different sources was noticed in some European countries (Von Hunolstein et al 2002). Likewise, Brazilian C. diphtheriae strains exhibited resistance to different drugs used in antimicrobial therapy.…”

Antimicrobial Efficacy of Curcumin Formulations by Photodynamic Therapy

“…The standard treatment of infectious PTs consists in the administration of antibiotics, including penicillin. However, some bacteria are resistant to antibiotics, as penicillin, due to their frequent use [4]. Microbial genetic mutations can modify the drug metabolism through protein binding and cell permeability [5].…”