Diagnosis is mainly done by:
Blood test and blood culture
Sputum culture – lungs and bronchi
Chest Xray – In the cases of Pneumonia, tuberculosis and other infections.
1. culture-based methods;
2. nucleic acid amplification technology (NAAT)-based assays.
Culture based method for CRE screening:
Culture based methods have been widely used for CRE screening, several different cultural approaches have been described
NAAT for molecular screening:
Molecular based methods (NAAT) for CRE screening usually detect the presence of one or more genes. For these characteristics these assays are able to identify only previously known resistance determinants.
NAAT-based assays validated for carbapenemase genes detection from rectal swabs can also be used as a confirmatory test for suspected colonies identified by culture-based methods, although not all commercial assays have an on-label indication for this.
The three types of NAAT based assays for the Surveillance of CRE is as follows:
In house molecular methods
Commercial molecular assays
Rapid/easy to use commercial molecular assays:
In house molecular methods can reveal best level of sensitivity and specificity . Moreover, these assays are less expensive if compared to molecular commercial method. Also it has important disadvantages are low level of automation, standardization and validation, and suboptimal inter-laboratory reproducibility.
Commercial molecular assays:
they are highly sensitive, specific and standardized, with TAT of few hours; the level of automation of these methods can vary from poor (need of sample preparation step, including extraction or lysis, and/or multiple hands-on steps), to good, but for all these assays laboratory experience and equipment are required.
Rapid/easy to use commercial molecular assays (REU-CMA) :
They might provide the same high standard of quality of results with shorter hands-on time and TAT (less than 1 h) and no requirement for batching