A biochemical test (NitroSpeed-Carba NP test) was developed to identify carbapenemase production in Enterobacterales and to discriminate between the different types of clinically-significant carbapenemases (Ambler class A, B and D). It is based on two main features, namely the hydrolysis by all ß-lactamases including carbapenemases of the nitrocefin substrate, and the capacity of ertapenem to prevent this hydrolysis for all ß-lactamases except carbapenemases. Specific carbapenemase inhibitors of class A (avibactam, vaborbactam), class B (dipicolinic acid) and class D (avibactam) were used to inhibit the nitrocefin hydrolysis and to allow the identification of the carbapenemase types with a turn-around-time of ca. 30 min. The test was evaluated with a collection of 248 clinical enterobacterial isolates including 148 carbapenemase producers and 100 non-carbapenemase producers. Its overall sensitivity and specificity were 100% and 97.1%, respectively, including detection of all types of OXA-48-like carbapenemases. For the detection of the carbapenemase type including strains that produce double carbapenemases, the sensitivity was 100%, 97% and 100% for the detection of class A, B, and D, respectively. This easy-to-implement test may contribute to optimize the choice of the ß-lactam/ß-lactamase inhibitor combinations for treating infection due to carbapenemase producers.

The global spread of extended-spectrum-β-lactamase (ESBL) is a matter of great concern given high morbidity and mortality associated with invasive infections.…

Objectives: To evaluate the biochemical Rapid ESBL NP ® (Liofilchem, Italy) for the rapid detection of extended-spectrum ß-lactamases (ESBL) in Enterobacterales.Methods: A total of 100 clinical Gram-negative strains (40 ESBL producers with or without cephalosporinase, 43 carbapenemase producers with or without additional ESBL, eight AmpCtype producers, six penicillinase producers and three non-β-lactamase producers) were tested using this colorimetric technique. Results:The overall sensitivity and specificity of the test were found to be 93.9% and 98.5%, respectively. This test is rapid (turn-around-time of 40-45 min), easy to perform, and reliable for identification of ESBL producers. Conclusion:The Rapid ESBL NP ® test allows differentiation between ESBL producers on one hand, and non ESBL-producers or isolates expressing combined mechanisms of resistance on the other hand.

No abstract

Sir, Antimicrobial resistance is a serious and growing threat for global public health. In the European Union, Iceland and Norway, infections caused by antibiotic-resistant organisms are estimated to be responsible of 25,000 deaths per year [1]. A Swiss expert group on infectious diseases and hospital hygiene (Swissnoso) estimates that approximately 70,000 nosocomial infections occurs yearly, among which, nearly 2.9% end fatally for the patients [2]. In addition, attributable mortality to multidrug-resistant bacteria, mostly Gramnegatives, has been recently reported from Switzerland [3]. The most clinically-significant and emerging resistant determinants are: (1) the extended-spectrum β-lactamases (ESBL) that confer resistance to all β-lactams except cephamycins and carbapenems, (2) the carbapenemases that confer resistance to virtually all β-lactams, and (3) the 16S rRNA methylases that confer resistance to all aminoglycosides by methylation of the aminoglycosides target, namely the 16S ribosomal RNA. We report here the colonization/infection of a patient hospitalized in India with six unrelated multidrug-resistant Gram-negative isolates who was transferred to Switzerland.