Molecular characteristic of mcr-1 producing Escherichia coli in a Chinese university hospital.

BACKGROUND: Colistin has been considered as a last-line treatment option in severe infections caused by multidrug-resistant (MDR) gram-negative pathogens. However, the emergence of the mobile colistin resistance gene (mcr-1) has challenged this viewpoint. The aim of this study is to explore the prevalence of mcr-1 in Escherichia coli (E. coli) in a Chinese teaching hospital, and investigate their molecular characteristics. METHODS: A total of 700 E. coli isolates were used to screen mcr-1 by PCR and sequencing in a Chinese university hospital from August 2014 to August 2015. Susceptibility test of mcr-1-producing isolates was determined by Vitek -2 Compact system. 26 virulence factors (VFs), phylogenetic groups, Multi-locus sequence typing (MLST), and DNA Fingerprinting (ERIC-PCR) of strains were investigated by PCR. RESULTS: Four (0.6%) mcr-1 producing E. coli isolates were found in this study. The results of antibiotic susceptibility test showed that all four isolates were resistant to colistin, ciprofloxacin, levofloxacin, cefazolin, and trimethoprim/sulfamethoxazole, and were susceptible to amikacin, ertapenem and imipenem. In addition, all 4 isolates exhibited high-level resistance to aztreonam, cefotaxime and gentamicin. The numbers of VFs contained in mcr-1 positive isolates were no more than 4 in our study. MLST result demonstrated that these isolates were assigned to two sequence types: ST156 and ST167. The result of phylogenetic analysis showed that four mcr-1-positive isolates belong to two phylogenetic groups: A and B1 group. ERIC-PCR showed that four mcr-1 positive strains were categorized into three different genotypes. CONCLUSIONS: Our study demonstrated a low prevalence of mcr-1 in E. coli clinical isolates in a Chinese teaching hospital, and we have gained insights into the molecular characteristics of these mcr-1-positive strains. Increasing the surveillance of these infections, as well as taking effective infection control measures are urgently needed to take to control the transmission of mcr-1 gene.

High prevalence of metallo-ß-lactamase among carbapenem-resistant Klebsiella pneumoniae in a teaching hospital in China.

The aim of this study was to characterize the carbapenemases in carbapenem-resistant Klebsiella pneumoniae (CR-KP) from a Chinese teaching hospital. A total of 40 CR-KPs were screened for the presence of carbapenemases. Minimum inhibitory concentrations were determined by agar dilution. The modified Hodge test was used for the detection of carbapenemase production. Carbapenemase, extended-spectrum ß-lactamase, and AmpC genes were detected using polymerase chain reaction (PCR) and sequencing. A conjugation test was performed using a broth culture mating method, transferred plasmids were typed by PCR-based replicon typing, and clonal relatedness was investigated by enterobacterial repetitive intergenic consensus sequences PCR (ERIC-PCR) and multilocus sequence typing (MLST). The results revealed that modified Hodge test was positive for 28 CR-KPs, and CR-KPs exhibited high resistance rates against various antibiotics, except colistin (5.0%) and tigecycline (22.5%). ERIC and MLST profiles showed no clonal outbreak. PCR demonstrated a high prevalence rate (55.0%, 22/40) of metallo-ß-lactamases (MBLs) in CR-KPs. IMP-4, IMP-8, NDM-1, and KPC-2 were identified in 14 (35.0%), 7 (17.5%), 2 (5.0%), and 7 (17.5%) isolates, respectively. Notably, 2 CR-KPs coproduced 2 carbapenemases simultaneously (IMP-8/NDM-1 and IMP-4/KPC-2). In vitro transfer of carbapenem resistance was successful for 11 MBL-producing CR-KPs. The extended spectrum ß-lactamase genes were detected in 30 (75.0%) of these CR-KPs. To the best of our knowledge, this is the first report focusing on carbapenem resistance in K. pneumoniae due to metalloenzymes in China. Screening and surveillance of MBLs in Enterobacteriaceae is urgently needed in this region to control and prevent the spread of these resistance determinants.

The UDP glucose: flavonoid-3-O-glucosyltransferase (UFGT) gene regulates anthocyanin biosynthesis in litchi (Litchi chinesis Sonn.) during fruit coloration.

We analyzed a litchi cultivar that included three phenotypes for pericarp color, ranging from green, indicating the absence of anthocyanins, to yellow, and red. Anthocyanins, chlorophylls, carotenoids, and flavonoids were measured in the three stages. Fruit coloration of red-skinned litchi was mainly due to higher flavonols, and anthocyanin pigments, lower chlorophyll (higher chlorophyll degradation). Expression of four genes of the anthocyanin pathway coding for phenylalanine ammonialyase, chalcone synthase, flavanone-3-hydroxylase, and the UDP-glucose: flavonoid-3-O-glucosyltransferase (UFGT), was analyzed by RT-PCR at three developmental stages from before the onset of ripening to full maturity. Gene expression patterns were compared to anthocyanin metabolites. The contents of anthocyanins and flavonols in the pericarps were consistent with the higher mRNA levels of UFGT, while, transcription of the other gene was not expected to follow the anthocyanin content. We suggest that UFGT might play an important role in anthocyanin biosynthesis in the pericarp of litchi. Thus, UFGT expression strongly influences fruit coloration in litchi.

Fecal carriage of carbapenem-resistant Enterobacteriaceae in a Chinese university hospital.

BACKGROUND: Carbapenem-resistant Enterobacteriaceae (CRE) is widespread in China. To date, no study available has specifically determined the prevalence and risk factors of inpatients with CRE intestinal colonization in this region. METHODS: Stool samples were screened for the presence of CRE in a Chinese university hospital. A case-control study was performed to identify risk factors associated with CRE fecal colonization. Case patients were those who had CRE colonization. Control subjects had no microbiologic evidence of CRE colonization. Clinical data were obtained from the medical record. RESULTS: The prevalence of CRE was 6.6% (20/303 patients), of which 8 had carbapenemase-producing isolates. KPC-2, IMP-4, and NDM-1 were detected from these isolates. Hospital readmissions (odds ratio [OR], 58.067; 95% confidence interval [95% CI]: 5.517-611.134; P = .001), sickbed changes (OR, 45.904; 95% CI: 8.484-248.376; P < .001), invasive procedures (OR, 8.322; 95% CI: 1.996-34.690; P = .004), and vancomycin (OR, 11.552; 95% CI: 1.155-115.574; P = .037) were independently associated with CRE colonization. CONCLUSION: This study demonstrated that asymptomatic intestinal carriage of CRE was relatively common in one region of China. Our study suggested that the implementation of effective infection control measures is urgently required to control the transmission of CRE in health care facilities in this country.