The emerging NDM carbapenemases

Extraintestinal Pathogenic Escherichia coli: A Combination of Virulence with Antibiotic Resistance

Escherichia coli represents an incredible versatile and diverse enterobacterial species and can be subdivided into the following; (i) intestinal non-pathogenic, commensal isolates. (ii) Intestinal pathogenic isolates and (iii) extraintestinal pathogenic E. coli or ExPEC isolates. The presence to several putative virulence genes has been positively linked with the pathogenicity of ExPEC. E. coli remains one of the most frequent causes of nosocomial and community-acquired bacterial infections including urinary tract infections, enteric infections, and systemic infections in humans. ExPEC has emerged in 2000s as an important player in the resistance to antibiotics including the cephalosporins and fluoroquinolones. Most importantly among ExPEC is the increasing recognition of isolates producing “newer β-lactamases” that consists of plasmid-mediated AmpC β-lactamases (e.g., CMY), extended-spectrum β-lactamases (e.g., CTX-M), and carbapenemases (e.g., NDM). This review will highlight aspects of virulence associated with ExPEC, provide a brief overview of plasmid-mediated resistance to β-lactams including the characteristics of the successful international sequence types such as ST38, ST131, ST405, and ST648 among ExPEC.

Phenotypic, biochemical, and molecular techniques for detection of metallo-β-lactamase NDM in Acinetobacter baumannii

Seven NDM-positive Acinetobacter baumannii isolates of worldwide origin were studied to evaluate the best technique for their identification. Detection of carbapenemase producers based on the measurement of carbapenemase activity by UV spectrophotometry (as for A. baumannii strains producing other types of carbapenemase), or by the modified Hodge test, failed. Inhibition activity using EDTA was a sensitive technique but lacked specificity compared to molecular techniques, which remain the gold standard.

Nosocomial clustering of NDM-1-producing Klebsiella pneumoniae sequence type 340 strains in four patients at a South Korean tertiary care hospital

In November 2010, NDM-1-producing Klebsiella pneumoniae (NDMKP) was identified for the first time in South Korea from four patients with no history of traveling abroad who stayed for 21 to 205 days in a tertiary care hospital. All were sequence type (ST) 340 and had nearly identical XbaI pulsed-field gel electrophoresis (PFGE) patterns. The bla(NDM-1)-carrying plasmids were in the IncN group, with sizes ranging from 50 to 200 kb. These findings suggest that NDMKP had already been introduced into South Korea before this clustering was found.