Sending instructions for Gram Negative Bacilli

1. Selection criteria

For Enterobacteriaceae:

  • Suspicion of CPE: K.pneumoniae or E. coli with decreased susceptibility (intermediate or resistant) to meropenem or another carbapenem (e.g.: ertapenem) by local susceptibility testing method.
    Other species of Enterobacteriaceae should not be sent except in case of suspicion of outbreaks (more than one sporadic case).
  • Suspicion of ESBL: strain cefotaxime,ceftriaxone and/or ceftazidime resistant.


For Pseudomonas and Acinetobacter spp:

  • Strains with decreased susceptibility to imipenem and/or meropenem (not ertapenem which intrinsically lacks significant  activity against these two organisms)
  • Strain resistant to all antibiotics


2. Sending of the strains

  • Fresh (<24h) and pure culture subcultured from a single colony on a non-chromogenic, non-selective media and antibiotics-free media (including disk diffusion plates which should be avoided). Preferred culture on blood agar plate with individual colonies visualized and avoid use of agar tube.


  • The completed isolate submission form and a copy of the susceptibility results performed locally must be attached to the strain, please correctly specify the address and the email address of the contact person from the referring laboratory.


  • Please join the following submission form to your strain(s)

Request of characterization of resistance mechanisms :download “CPE _submission form"

Request of molecular typing :download “Typing _submission form"


  • Strains can be sent at room temperature to the following address:


Laboratory of microbiology
National Reference Center of Gram Negative Bacilli Antibiotic Resistant
Pr. Te-Din Huang or Pr. Olivier Denis 
Avenue Dr Gaston Therasse ,1
BE-5530 Yvoir.

3. Unacceptable request

The NRC may reject the strain for analysis for the following reasons:

  • Absence or incomplete submission forms
  • Culture specimen without a copy of the susceptibility results or/and without identification reference
  • Damaged sample (broken tubes, crushed agar plates)
  • Contamination of the received culture specimen
  • Misidentification (discrepancy between the identification provided on the isolate form and the identification obtained on the strain received)
  • Duplicate bacterial isolate (same species, same susceptibility profil from several repeated sampling or several anatomical sites in the same patient)
  • Bacterial isolate susceptible to all carbapenems
  • Bacterial isolate confirmed CPE by commercial testing (antigen or molecular test) in your laboratory
  • Bacterial isolate belonging to a species/genus other than Enterobacteriaceae, Pseudomonas spp.,Acinetobacter spp.


4. Communication of results

The NRC is committed to meeting the following deadlines:

  • Within 3 working days after receipt of the strain for the temporary protocol containing the result of screening for carbapenemase production. The protocol is sent by email.
  • Within 8 working days after receipt of the strain for the definitive protocol with the complete final results. The definitive protocol is sent by post.

Rue Docteur Gaston Therasse 1, 5530 Yvoir (Belgique)