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Objectives: To characterize blaIMP-4-carrying plasmids originating from inpatients in Hong Kong.Methods: Sixteen blaIMP-4-carrying plasmids identified among Enterobacteriaceae (nine Escherichia coli, four Klebsiella pneumoniae, two Citrobacter freundii and one Enterobacter cloacae) recovered from 15 patients were characterized. The isolates, collected during January 2010 to December 2013, were retrospectively investigated by plasmid sequencing, molecular and fitness studies.Results: The blaIMP-4-carrying plasmids belonged to the IncN ST7 lineage (∼50 kb). Twelve of the 16 plasmids were epidemiologically linked to seven different regions in China. Alignment of the complete plasmid sequences showed identical plasmid backbones and two highly similar resistance regions, each carrying one of two resistance genes (blaIMP-4 and qnrS1). The blaIMP-4 was detected in a class 1 integron (containing blaIMP-4 and intron Kl.pn.13) that is part of an IS6100-IS26 transposon-like structure. The nine E. coli carrying the epidemic plasmid belonged to multiple multilocus STs (six ST542, one ST131, one ST657 and one ST3177). Fitness assays performed on E. coli J53 recipients showed that the presence of the epidemic plasmid did not have a significant biological cost.Conclusions: This study identified a blaIMP-4-carrying IncN ST7 plasmid disseminated among multiple enterobacterial species originating from patients with epidemiological links to different regions in China. [ABSTRACT FROM AUTHOR]

Recent EUCAST advice asserts that, with low breakpoints, susceptibility results for cephalosporins and carbapenems can be reported ‘as found’, even for strains with extended-spectrum β-lactamases (ESBLs) and carbapenemases. The CLSI has similar advice, but with higher ceftazidime and cefepime breakpoints than those of EUCAST. Pharmacodynamic and animal data are used to support these views, along with some analysis of clinical case series. We contend that such advice is misguided on three counts. First, whilst there are cases on record where cephalosporins and carbapenems have proved effective against infections due to low-MIC ESBL producers and low-MIC carbapenemase producers, respectively, there are similar numbers of cases where such therapy has failed. Second, routine susceptibility testing is less precise than in research analyses, meaning that ESBL and carbapenemase producers with ‘real’ MICs of 1–8 mg/L will oscillate between susceptibility categories according to who tests them and how. Third, although EUCAST continues to advocate ESBL and carbapenemase detection for epidemiological purposes, the likely consequence of not seeking these enzymes for treatment purposes is that some laboratories will not seek them at all, leading to a loss of critical infection control information. In short, it is prudent to continue to seek ESBLs and carbapenemases directly and, where they are found, generally to avoid substrate drugs as therapy. [ABSTRACT FROM PUBLISHER]

The article discusses the clinical case of a one-year-old infant who was diagnosed with carbapenem-resistant Enterobacteriaceae (CRE). The patient was found to have New Delhi metallo-Β-lactamase (NDM)-1-producing Enterobacteriaceae. The authors concluded that the infant seemed to have acquired the blaNDM-1 gene during hospitalization in Hunan Province, India.

The article examines the prevalence of Escherichia coli producing extended-spectrum Β-lactamases (ESBL) in Hong Kong, China, based on the database of microbiology from a healthcare region from 2000 to 2010. The database was extracted and analyzed using linear regression in order to assess changes in the burden of Escherichia coli bacteremia. Variables such as hospital admissions and patient-days are also considered in this assessment.

The article discusses a study to determine the effect of implementing the new Clinical and Laboratory Standards Institute (CLSI) imipenem susceptibility breakpoints for Enterobacteriaceae in Hong Kong, China. It was noted that applying the new CLSI criteria drastically changed the susceptibility rates for some isolate groups. The reduction in imipenem susceptibility rate was dramatic for Proteus spp., Enterobacter spp., Providencia spp. and Morganella spp.

The article discusses a study which examined the presence of the O25-sequence type 131 clonal group among Escherichia coli isolates from a prospective cohort of female outpatients with cystitis in Hong Kong, China. 28.8% of patients had a history of urinary tract infection. Information on the phylogenetic group distribution of the isolates is provided. Results of the study showed that O25b-ST131 isolates were accounted for 45.7% of ciprofloxacin-resistant patients.