Longitudinal Assessment of Antimicrobial Susceptibility among Gram-Negative and Gram-Positive Organisms Collected from Italy as Part of the Tigecycline Evaluation and Surveillance Trial between 2004 and 2011

Abstract

The Tigecycline Evaluation and Surveillance Trial (T.E.S.T.) was initiated in 2004 to longitudinally monitor the activity of the broad-spectrum glycylcycline antimicrobial tigecycline, and a suite of comparator agents, against an array of clinically important bacterial pathogens worldwide. In this report, we examine the activity of tigecycline and comparators against a collection of 13,245 clinical isolates, both Gram-positive (n = 4,078 and Gram-negative (n = 9,167), collected from 27 centres in Italy between 2004 and 2011. Susceptibility was established according to Clinical Laboratory Standards Institute guidelines. Tigecycline and linezolid exhibited very good activity against Gram-positive pathogens, with MIC90s ranging from 0.06 to 0.25 mg/L and 1–4 mg/L, respectively; vancomycin and the carbapenems also showed good activity against select Gram-positive pathogens. Tigecycline was the most active agent against Gram-negative pathogens (except P. aeruginosa), with MIC90s ranging from 0.25–2 mg/L (16 mg/L for P. aeruginosa). Amikacin and the carbapenems also possessed good activity against many Gram-negative pathogens here. ESBL-positive E. coli increased in prevalence from 2004 to 2011, while ESBL-positive Klebsiella spp., vancomycin-resistant enterococci and MRSA decreased in prevalence. Linezolid, tigecycline and vancomycin susceptibility were very stable over the course of this study, while susceptibility to ampicillin, piperacillin-tazobactam, ceftriaxone and levofloxacin varied over time according to pathogen; minocycline and cefepime susceptibility among several pathogens decreased during this study.

Assessment of the Activity of Tigecycline against Gram-Positive and Gram-Negative Organisms Collected from Italy between 2012 and 2014, as Part of the Tigecycline Evaluation and Surveillance Trial (T.E.S.T.)

“…Our report shows comparable rates of ESBL-producing K. pneumoniae between 2012 and 2014 to that reported in the earlier study by Stefani et al (22% and 24% respectively) [7]. However, the number of ESBL-producing E. coli isolates has increased between the two studies, from 25% (2004–2011), to 31% (2012–2014) [7].…”

“…This report on T.E.S.T. data from Italy between 2012 and 2014 is an update of the previous publication by Stefani et al which presented data from the 2004 to 2011 time period [7]. Comparisons between the two studies are limited because the current report uses the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria for determining susceptibility and resistance and the previous publication used the Clinical and Laboratory Standards Institute (CLSI) interpretive criteria [8,11].…”

“…centers between 2012 and 2014. We also discuss the 2012 to 2014 data in comparison to the 2004 to 2011 data published in the earlier paper by Stefani et al [7]. …”

“…is a global surveillance study which has been ongoing since 2004 and monitors the in vitro antibacterial activity of tigecycline and comparator agents against a range of clinically important Gram-positive and Gram-negative organisms. This paper serves as an update of the one by Stefani et al, which covered the period 2004 to 2011 [7]. Here, we report on antimicrobial resistance among isolates of Gram-positive and Gram-negative organisms and their resistant phenotypes collected from Italian T.E.S.T.…”

“…However, the number of ESBL-producing E. coli isolates has increased between the two studies, from 25% (2004–2011), to 31% (2012–2014) [7]. Tigecycline and meropenem were the most active agents against E. coli and its resistant phenotype (≥98% susceptible); this result is comparable with that by Stefani et al [7]. A surveillance study by Jones et al monitored antimicrobial resistance in 21 European countries, including Italy, in 2011.…”