Clinical epidemiology and molecular analysis of extended-spectrum-ß-lactamase-producing Escherichia coli in Nepal: characteristics of sequence types 131 and 648.

Recently, CTX-M-type extended-spectrum-ß-lactamase (ESBL)-producing Escherichia coli strains have emerged worldwide. In particular, E. coli with O antigen type 25 (O25) and sequence type 131 (ST131), which is often associated with the CTX-M-15 ESBL, has been increasingly reported globally; however, epidemiology reports on ESBL-producing E. coli in Asia are limited. Patients with clinical isolates of ESBL-producing E. coli in the Tribhuvan University teaching hospital in Kathmandu, Nepal, were included in this study. Whole-genome sequencing of the isolates was conducted to analyze multilocus sequence types, phylotypes, virulence genotypes, O25b-ST131 clones, and distribution of acquired drug resistance genes. During the study period, 105 patients with ESBL-producing E. coli isolation were identified, and the majority (90%) of these isolates were CTX-M-15 positive. The most dominant ST was ST131 (n = 54; 51.4%), followed by ST648 (n = 15; 14.3%). All ST131 isolates were identified as O25b-ST131 clones, subclone H30-Rx. Three ST groups (ST131, ST648, and non-ST131/648) were compared in further analyses. ST648 isolates had a proportionally higher resistance to non-ß-lactam antibiotics and featured drug-resistant genes more frequently than ST131 or non-ST131/648 isolates. ST131 possessed the most virulence genes, followed by ST648. The clinical characteristics were similar among groups. More than 38% of ESBL-producing E. coli isolates were from the outpatient clinic, and pregnant patients comprised 24% of ESBL-producing E. coli cases. We revealed that the high resistance of ESBL-producing E. coli to multiple classes of antibiotics in Nepal is driven mainly by CTX-M-producing ST131 and ST648. Their immense prevalence in the communities is a matter of great concern.

Multidrug-resistant Acinetobactor baumannii isolated from a traveler returned from Brunei.

We report a case of multidrug-resistant (MDR) Acinetobactor baumannii isolates obtained from a traveler returned from Brunei. Whole-genome sequencing analysis revealed that the isolates harbored blaOxA-23 and armA. The minimum inhibitory concentrations of antibiotics against the strain were as follows: imipenem, 32 µg/ml; meropenem, 32 µg/ml; ciprofloxacin, 16 µg/ml; amikacin, ≧ 1024 µg/ml; arbekacin, ≧ 1024 µg/ml; aztreonam, 64 µg/ml; colistin, 4 µg/ml. A. baumannii harboring both blaOxA-23 and armA is rarely reported in Japan, and, to the best of our knowledge, this is the second report of A. baumannii harboring both resistant genes in Japan.

Evaluation of an automated rapid diagnostic test for detection of Clostridium difficile.

The Verigene Clostridium difficile Nucleic Acid Test (Verigene CDF Test) (Nanosphere, Northbrook, IL, USA) is a new multiplex qualitative polymerase chain reaction (PCR) test used to detect C. difficile toxin genes in fecal specimens. To evaluate the performance of the new method, we tested 69 fecal samples from patients with suspected C. difficile infection using the Verigene CDF test, an enzyme immunoassay (EIA) and PCR following anaerobic fecal culture. The sensitivity, specificity, and accuracy of the Verigene CDF test were 96.7% (29/30), 97.4% (38/39), and 97.1% (67/69) respectively, using PCR following fecal culture as a reference method. We also analyzed the potential clinical impact of the Verigene CDF test using chart reviews of the 69 patients with suspected C. difficile infection and found that 11 of the 69 patients were incorrectly diagnosed, and the Verigene CDF test would have led to them receiving more appropriate management including practice of treatment and contact precaution, although, of the 69 patients, there are two whose samples were incorrectly identified with the Verigene CDF test. The Verigene CDF test will have a positive impact on patient care.

Dissemination in Japan of multidrug-resistant Pseudomonas aeruginosa isolates producing IMP-type metallo-ß-lactamases and AAC(6')-Iae/AAC(6')-Ib.

The spread throughout Japan of antibiotic-resistance factors in multidrug-resistant (MDR) Pseudomonas aeruginosa isolates was investigated epidemiologically, using immunochromatographic assays specific for IMP-type metallo-ß-lactamases (IMPs) and aminoglycoside 6'-N-acetyltransferase [AAC(6')]-Iae and -Ib. Three hundred MDR P. aeruginosa isolates were obtained during each of two years, 2011 and 2012, from 190 hospitals in 39 prefectures in Japan. The percentage of P. aeruginosa isolates producing IMPs, AAC(6')-Iae or AAC(6')-Ib increased significantly from 170/300 (56.7%) in 2011 to 230/300 (76.7%) in 2012, with 134/170 (78.8%) in 2011 and 179/230 (77.8%) in 2012 producing both IMP and either AAC(6')-Iae or AAC(6')-Ib. The MICs of antibiotics, including cephalosporins and carbapenems, were markedly higher for isolates that did than did not produce these resistance factors. These results indicated that MDR P. aeruginosa producing IMPs, AAC(6')-Iae or AAC(6')-Ib have spread throughout Japan and that these antibiotic-resistance factors are useful markers for monitoring MDR P. aeruginosa in Japan.

Molecular and epidemiological characterization of IMP-type metallo-ß-lactamase-producing Enterobacter cloacae in a Large tertiary care hospital in Japan.

IMP-type metallo-ß-lactamase enzymes have been reported in different geographical areas and in various Gram-negative bacteria. However, the risk factors and epidemiology pertaining to IMP-type metallo-ß-lactamase-producing Enterobacter cloacae (IMP-producing E. cloacae) have not been systematically evaluated. We conducted a retrospective, matched case-control study of patients from whom IMP-producing E. cloacae isolates were obtained, in addition to performing thorough molecular analyses of the clinically obtained IMP-producing E. cloacae isolates. Unique cases with IMP-producing E. cloacae isolation were included. Patients with IMP-producing E. cloacae were matched to uninfected controls at a ratio of 1 to 3. Fifteen IMP-producing E. cloacae cases were identified, with five of the isolates being obtained from blood, and they were matched to 45 uninfected controls. All (100%) patients from whom IMP-producing E. cloacae isolates were obtained had indwelling devices at the time of isolation, compared with one (2.2%) uninfected control. Independent predictors for isolation of IMP-producing E. cloacae were identified as cephalosporin exposure and invasive procedures within 3 months. Although in-hospital mortality rates were similar between cases and controls (14.3% versus 13.3%), the in-hospital mortality of patients with IMP-producing E. cloacae-caused bacteremia was significantly higher (40%) than the rate in controls. IMP-producing E. cloacae isolates were frequently positive for other resistance determinants. The MICs of meropenem and imipenem were not elevated; 10 (67%) and 12 (80%) of the 15 IMP-producing E. cloacae isolates had a MIC of ≤ 1 µg/ml. A phylogenetic tree showed a close relationship among the IMP-producing E. cloacae samples. Indwelling devices, exposure to cephalosporin, and a history of invasive procedures were associated with isolation of IMP-producing E. cloacae. Screening for carbapenemase production is important in order to apply appropriate clinical management and infection control measures.

Evaluation of an automated rapid diagnostic assay for detection of Gram-negative bacteria and their drug-resistance genes in positive blood cultures.

We evaluated the performance of the Verigene Gram-Negative Blood Culture Nucleic Acid Test (BC-GN; Nanosphere, Northbrook, IL, USA), an automated multiplex assay for rapid identification of positive blood cultures caused by 9 Gram-negative bacteria (GNB) and for detection of 9 genes associated with ß-lactam resistance. The BC-GN assay can be performed directly from positive blood cultures with 5 minutes of hands-on and 2 hours of run time per sample. A total of 397 GNB positive blood cultures were analyzed using the BC-GN assay. Of the 397 samples, 295 were simulated samples prepared by inoculating GNB into blood culture bottles, and the remaining were clinical samples from 102 patients with positive blood cultures. Aliquots of the positive blood cultures were tested by the BC-GN assay. The results of bacterial identification between the BC-GN assay and standard laboratory methods were as follows: Acinetobacter spp. (39 isolates for the BC-GN assay/39 for the standard methods), Citrobacter spp. (7/7), Escherichia coli (87/87), Klebsiella oxytoca (13/13), and Proteus spp. (11/11); Enterobacter spp. (29/30); Klebsiella pneumoniae (62/72); Pseudomonas aeruginosa (124/125); and Serratia marcescens (18/21); respectively. From the 102 clinical samples, 104 bacterial species were identified with the BC-GN assay, whereas 110 were identified with the standard methods. The BC-GN assay also detected all ß-lactam resistance genes tested (233 genes), including 54 bla(CTX-M), 119 bla(IMP), 8 bla(KPC), 16 bla(NDM), 24 bla(OXA-23), 1 bla(OXA-24/40), 1 bla(OXA-48), 4 bla(OXA-58), and 6 blaVIM. The data shows that the BC-GN assay provides rapid detection of GNB and ß-lactam resistance genes in positive blood cultures and has the potential to contributing to optimal patient management by earlier detection of major antimicrobial resistance genes.

Parvimonas micra as a causative organism of spondylodiscitis: a report of two cases and a literature review.

Spondylodiscitis caused by Parvimonas micra, a rarely reported infection, might be under-detected using conventional methods. This report of the detection and treatment of two cases of spondylodiscitis due to P. micra and review of the literature indicates that the use of gene sequencing methods might improve the accuracy of diagnosing this infection.

Smad7-deficient mice show growth retardation with reduced viability.

Smad7 is an inhibitory molecule induced by members of the transforming growth factor-ß (TGF-ß) family, including TGF-ß, activin, nodal and bone morphogenetic proteins (BMPs). To elucidate the in vivo functions of Smad7, we generated conditional Smad7-knockout mice in which the Mad homology 2 (MH2) domain and the poly (A) signal sequence were flanked with loxP sites (floxed). The Smad7-floxed mice exhibited no obvious phenotype. Smad7 total-null mice on a C57BL/6 background died within a few days of birth, whereas mice with an ICR background developed to adulthood but were significantly smaller than wild-type mice. Unexpectedly, phospho-Smad2 and phospho-Smad3 were decreased in Smad7-deficient mouse embryonic fibroblast (MEF) cells, whereas phospho-Smad1/5/8 was similarly expressed in wild-type and Smad7-deficient MEF cells. Moreover, expression levels of TGF-ß type I receptor (ALK5) were higher in Smad7-deficient MEF cells than in wild-type MEF cells. Plasminogen activator inhibitor-1 (PAI-1) and inhibitor of differentiation-1 (Id-1) mRNA were similarly expressed in wild-type and Smad7-deficient MEF cells. Some differences were observed in mitogen-activated protein kinase (MAPK)-signalling between wild-type and Smad7-deficient MEF cells. We demonstrated that Smad7 plays an important role in normal mouse growth and provide a useful tool for analysing Smad7 functions in vivo.

The ALK-5 inhibitor A-83-01 inhibits Smad signaling and epithelial-to-mesenchymal transition by transforming growth factor-beta.

Transforming growth factor (TGF)-beta signaling facilitates tumor growth and metastasis in advanced cancer. Use of inhibitors of TGF-beta signaling may thus be a novel strategy for the treatment of patients with such cancer. In this study, we synthesized and characterized a small molecule inhibitor, A-83-01, which is structurally similar to previously reported ALK-5 inhibitors developed by Sawyer et al. (2003) and blocks signaling of type I serine/threonine kinase receptors for cytokines of the TGF-beta superfamily (known as activin receptor-like kinases; ALKs). Using a TGF-beta-responsive reporter construct in mammalian cells, we found that A-83-01 inhibited the transcriptional activity induced by TGF-beta type I receptor ALK-5 and that by activin type IB receptor ALK-4 and nodal type I receptor ALK-7, the kinase domains of which are structurally highly related to those of ALK-5. A-83-01 was found to be more potent in the inhibition of ALK5 than a previously described ALK-5 inhibitor, SB-431542, and also to prevent phosphorylation of Smad2/3 and the growth inhibition induced by TGF-beta. In contrast, A-83-01 had little or no effect on bone morphogenetic protein type I receptors, p38 mitogen-activated protein kinase, or extracellular regulated kinase. Consistent with these findings, A-83-01 inhibited the epithelial-to-mesenchymal transition induced by TGF-beta, suggesting that A-83-01 and related molecules may be useful for preventing the progression of advanced cancers.