dark pink to red
Klebsiella, Enterobacter, Citrobacter
CHROMagar™ MH Orientation is a chromogenic Mueller Hinton agar. This product was developed with the aim to speed up the time to obtain results by combining the chromogenic differentiation of the species in the sample, and the antibiotic susceptibility test. This tool allows a same-day results in both fields, the identification and susceptibility, directly in the primary culture, contrary to the concomitant traditional protocol which takes 48 hours.
An evaluation was carried by AB Biodisk in 2008, comparing the performances of our CHROMagar™ MH Orientation with the traditional Mueller-Hinton formulation 1. This study, carried with over 20 classical antimicrobial agents, concluded that the use of our medium with E-test strips can provide same day results.
CHROMagar™ MH Orientation has been used principally in two applications, but it certainly may find usefulness in many other cases. The first application is on samples from ICU patients with Ventilated Associated Pneumonia (VAP), which is one of the most frequent ICU nosocomial infections with high morbidity and mortality. Shortening the period in which empirical therapy can be optimized results in better outcomes. As stated by the Spanish team, leader in this protocol 2, plating respiratory samples directly onto CHROMagar™ MH Orientation is “a rapid procedure for antimicrobial susceptibility testing (...) crucial for modifying therapeutic regimens”.
The second application is the common Urine Tract Infections (UTI) for which physicians usually prescribe an empiric therapy. Urine samples with typical infection counts of 103-105 cfu/mL can be spread directly on this plate. Pluri-microbial samples as well as monomicrobial-contaminated samples can be easily investigated by this method. In this case also as in the VAP, the same-day identification and susceptibility results can confirm the empirical therapy, or help in the decision to change it.
References: 1 Engelhardt A. et al, Rapid E-test® MIC Testing Using CHROMagar™ And Mueller Hinton Agar For Gram Positive And Gram Negative Aerobes - ECCMID 2008 2 E. Cercenado et al, Evaluation of direct E-test on lower respiratory tract samples using a chromogenic agar medium: a rapid procedure for antimicrobial susceptibility testing - ECCMID 2009