Tigecycline-Induced Tooth Discoloration in Children Younger than 8 Years

Tetracycline may cause tooth discoloration when used in young children during tooth development. Whether tigecycline, a tetracycline derivative, has either a similar adverse event or not remains unclear. We assessed the discoloration of the permanent teeth of patients <8 years old after tigecycline exposure. These patients were identified through a retrospective chart review in a Chinese children’s hospital. Those who had at least one erupted permanent tooth after tigecycline exposure were interviewed, examined, and photographed by an experienced pediatric dentist and independently assessed by another senior dentist to detect tetracycline-like tooth discoloration. We identified 101 patients who were exposed to tigecycline, 12 of whom were included. The mean dose of tigecycline was 2.3 mg/kg/day (standard deviation, 0.6), and the median duration was 12.5 days (interquartile range [IQR], 8.0 to 19.3). The median age of exposure was 5.2 years (IQR, 4.5 to 7.4), and the median age of dental examination was 9.1 years (IQR, 9.0 to 10.3). Two patients (16.7%) developed yellow discoloration: a girl having yellow discoloration with white-to-yellow opacities in the upper lateral incisors and lower incisors, and a boy with a suspicious buccal yellow discoloration and enamel dysplasia in the second molars. The incidence and extent of tigecycline-associated dental adverse events remain unclear due to the small sample size and inadequate follow-up period.

In Vitro Susceptibility Testing of Omadacycline against Nontuberculous Mycobacteria (NTM)

Nontuberculous mycobacteria (NTM) infections are increasing globally. Mycobacterium avium complex (MAC) and M. abscessus complex are the most frequently encountered NTM and oral treatment options are extremely limited for these pathogens, especially for the M. abscessus complex. In this study, the in vitro potency of omadacycline, a new tetracycline derivative, was tested against 111 isolates of NTM. MIC testing was performed as recommended by the Clinical and Laboratory Standards Institute against 70 isolates of rapidly growing mycobacteria (RGM) of which >90% were tetracycline resistant. These included M. abscessus subsp. abscessus (20), M. abscessus subsp. massiliense (3), M. chelonae (15), M. immunogenum (7), the M. fortuitum group including six doxycycline resistant isolates (12), and the M. mucogenicum group including four doxycycline resistant isolates (10). Forty-one isolates of slowly growing mycobacteria (SGM) species including 16 isolates of MAC were also tested. Omadacycline was active against all RGM species with an MIC50 range of 0.004-0.25 and 0.06-1 μg/ml for 80% and 100% inhibition, respectively. For M. abscessus subsp. abscessus, MIC50 values were 0.06 and 0.12 μg/ml with 80% and 100% inhibition respectively. There was considerable trailing of the omadacycline endpoint with the RGM. MICs for tigecycline exhibited no trailing and were generally within 1-2 dilutions of the 100% inhibition omadacycline MIC values. While there was no trailing observed in SGM, omadacycline MICs were higher (MIC range 8->16 μg/ml, N = 41) as previously noted with tigecycline. This study supports further research of omadacycline including clinical trials for the treatment of RGM infections, especially M. abscessus.

In Vitro Activities of Omadacycline against Rapidly Growing Mycobacteria

ABSTRACT The in vitro activity of omadacycline, a new tetracycline derivative, was evaluated against isolates of Mycobacterium abscessus, Mycobacterium chelonae, and Mycobacterium fortuitum using a broth microtiter dilution assay. Omadacycline had MIC90 values of 2 μg/ml, 0.25 μg/ml, and 0.5 μg/ml, respectively. The in vitro activity of omadacycline against rapidly growing mycobacteria indicates that it may have the potential to improve therapy for infections caused by these organisms.