Tatsuya Tada

NDM-8 Metallo-β-Lactamase in a Multidrug-Resistant Escherichia coli Strain Isolated in Nepal

ABSTRACT A novel metallo-β-lactamase, NDM-8, was identified in a multidrug-resistant Escherichia coli isolate, IOMTU11 (NCGM37), obtained from the respiratory tract of a patient in Nepal. The amino acid sequence of NDM-8 has substitutions at positions 130 (Asp to Gly) and 154 (Met to Leu) compared with NDM-1. NDM-8 showed enzymatic activities against β-lactams similar to those of NDM-1.

Complete Genome Sequence of Highly Multidrug-Resistant Pseudomonas aeruginosa NCGM2.S1, a Representative Strain of a Cluster Endemic to Japan

We report the completely annotated genome sequence of Pseudomonas aeruginosa NCGM2.S1, a representative strain of a cluster endemic to Japan with a high level of resistance to carbapenem (MIC ≥ 128 μg/ml), amikacin (MIC ≥ 128 μg/ml), and fluoroquinolone (MIC ≥ 128 μg/ml).

Dissemination of 16S rRNA Methylase ArmA-Producing Acinetobacter baumannii and Emergence of OXA-72 Carbapenemase Coproducers in Japan

ABSTRACT Forty-nine clinical isolates of multidrug-resistant Acinetobacter baumannii were obtained from 12 hospitals in 7 prefectures throughout Japan. Molecular phylogenetic analysis revealed the clonal spread of A. baumannii sequence type 208 (ST208) and ST455 isolates harboring the armA gene and ST512 harboring the armA and blaOXA-72 genes. These findings show that A. baumannii isolates harboring armA are disseminated throughout Japan, and this is the first report to show that A. baumannii strains harboring blaOXA-72 and armA are emerging in hospitals in Japan.

Dissemination of multidrug-resistant Klebsiella pneumoniae clinical isolates with various combinations of carbapenemases (NDM-1 and OXA-72) and 16S rRNA methylases (ArmA, RmtC and RmtF) in Nepal

2008 0812M7303 Typhimurium 193 blaCTX-M-55 M 50 Thailand CHL, CIP, FFN, GEN, SUL, STR, TET 0811R10895 Typhimurium RDNC blaCTX-M-1 M 1 Unknown SUL,TET 0809W37247 Stanley blaCMY-2-like F 37 No AMC, CHL, FFN, SUL, STR, TET 0809F35063 Stanley blaCMY-2-like F 6 Unknown AMC, CHL, FFN, GEN, SUL, STR, TET 0808S63221 Typhimurium NT blaCMY-2-like M 20 Thailand AMC, CHL, FFN, SUL, STR, TET 0807F21428 Stanley blaCMY-2-like F 22 Thailand AMC, CHL, FFN, GEN, SUL, STR, TET 0806H16365 Stanley blaCMY-2-like M 2 Unknown AMC, CHL, FFN, GEN, SUL, STR, TET 0806R9615 Typhimurium U292 blaCTX-M-3 M 12 No None 0805R9530 Typhimurium NT blaCTX-M-14 M 47 Greece AMC, CHL, GEN, SUL, STR, TMP 2009 0911W58164 Heidelberg blaCTX-M-14 M 40 Egypt GEN, SUL, STR 0910W56953 subsp. enterica (I) blaCMY-2-like M 55 Thailand AMC, CHL, CIP, FFN, GEN, NAL, SUL, STR, TET 0910F48822 Isangi blaCMY-2-like, blaOXA-10 M <1 South Africa AMC, CHL, CIP, FFN, GEN, NAL, SUL, STR, TET, TMP

NDM-12, a Novel New Delhi Metallo-β-Lactamase Variant from a Carbapenem-Resistant Escherichia coli Clinical Isolate in Nepal

ABSTRACT A novel New Delhi metallo-β-lactamase variant, NDM-12, was identified in a carbapenem-resistant Escherichia coli clinical isolate obtained from a urine sample from a patient in Nepal. NDM-12 differed from NDM-1 by two amino acid substitutions (M154L and G222D). The enzymatic activities of NDM-12 against β-lactams were similar to those of NDM-1, although NDM-12 showed lower kcat/Km ratios for all β-lactams tested except doripenem. The blaNDM-12 gene was located in a plasmid of 160 kb.

Molecular epidemiology of multidrug-resistant Acinetobacter baumannii isolates in a university hospital in Nepal reveals the emergence of a novel epidemic clonal lineage.

The emergence of multidrug-resistant (MDR) Acinetobacter baumannii has become a serious medical problem worldwide. To clarify the genetic and epidemiological properties of MDR A. baumannii strains isolated from a medical setting in Nepal, 246 Acinetobacter spp. isolates obtained from different patients were screened for MDR A. baumannii by antimicrobial disk susceptibility testing. Whole genomes of the MDR A. baumannii isolates were sequenced by MiSeq™ (Illumina), and the complete genome of one isolate (IOMTU433) was sequenced by PacBio RS II. Phylogenetic trees were constructed from single nucleotide polymorphism concatemers. Multilocus sequence types were deduced and drug resistance genes were identified. Of the 246 Acinetobacter spp. isolates, 122 (49.6%) were MDR A. baumannii, with the majority being resistant to aminoglycosides, carbapenems and fluoroquinolones but not to colistin and tigecycline. These isolates harboured the 16S rRNA methylase gene armA as well as bla(NDM-1), bla(OXA-23) or bla(OXA-58). MDR A. baumannii isolates belonging to clonal complex 1 (CC1) and CC2 as well as a novel clonal complex (CC149) have spread throughout a medical setting in Nepal. The MDR isolates harboured genes encoding carbapenemases (OXA and NDM-1) and a 16S rRNA methylase (ArmA).

IMP-43 and IMP-44 Metallo-β-Lactamases with Increased Carbapenemase Activities in Multidrug-Resistant Pseudomonas aeruginosa

ABSTRACT Two novel IMP-type metallo-β-lactamase variants, IMP-43 and IMP-44, were identified in multidrug-resistant Pseudomonas aeruginosa isolates obtained in medical settings in Japan. Analysis of their predicted amino acid sequences revealed that IMP-43 had an amino acid substitution (Val67Phe) compared with IMP-7 and that IMP-44 had two substitutions (Val67Phe and Phe87Ser) compared with IMP-11. The amino acid residue at position 67 is located at the end of a loop close to the active site, consisting of residues 60 to 66 in IMP-1, and the amino acid residue at position 87 forms a hydrophobic patch close to the active site with other amino acids. An Escherichia coli strain expressing blaIMP-43 was more resistant to doripenem and meropenem but not to imipenem than one expressing blaIMP-7. An E. coli strain expressing blaIMP-44 was more resistant to doripenem, imipenem and meropenem than one expressing blaIMP-11. IMP-43 had more efficient catalytic activities against all three carbapenems than IMP-7, indicating that the Val67Phe substitution contributed to increased catalytic activities against carbapenems. IMP-44 had more efficient catalytic activities against all carbapenems tested than IMP-11, as well as increased activities compared with IMP-43, indicating that both the Val67Phe and Phe87Ser substitutions contributed to increased catalytic activities against carbapenems.

Biochemical Analysis of Metallo-β-Lactamase NDM-3 from a Multidrug-Resistant Escherichia coli Strain Isolated in Japan

ABSTRACT New Delhi metallo-β-lactamase-3 (NDM-3) was identified in a multidrug-resistant Escherichia coli isolate, NCGM77, obtained from the feces of a patient in Japan. The enzymatic activities of NDM-3 against β-lactams were similar to those of NDM-1, although NDM-3 showed slightly lower kcat/Km ratios for all the β-lactams tested except for doripenem. The genetic context for blaNDM-3 was tnpA-blaNDM-3-bleMBL-trpF-dsbC-tnpA-sulI-qacEdeltaI-aadA2-dfrA1, which was present on an approximately 250-kb plasmid.

Broad Detection of Diverse H5 and H7 Hemagglutinin Genes of Avian Influenza Viruses by Real-Time Reverse Transcription-PCR Using Primer and Probe Sets Containing Mixed Bases

ABSTRACT Real-time reverse transcription-PCR (RT-PCR) was developed for broad detection of diverse H5 and H7 genes in Eurasian and American lineages of avian influenza viruses by using primer and probe sets containing mixed bases. Optimal use of the mixed bases enabled us to minimize sequence mismatches and to broaden the gene detection spectrum without decreasing sensitivity.

Novel 6′-N-Aminoglycoside Acetyltransferase AAC(6′)-Iaj from a Clinical Isolate of Pseudomonas aeruginosa

ABSTRACT Pseudomonas aeruginosa NCGM1588 has a novel chromosomal class 1 integron, In151, which includes the aac(6′)-Iaj gene. The encoded protein, AAC(6′)-Iaj, was found to consist of 184 amino acids, with 70% identity to AAC(6′)-Ia. Escherichia coli transformed with a plasmid containing the aac(6′)-Iaj gene acquired resistance to all aminoglycosides tested except gentamicin. Of note, aac(6′)-Iaj contributed to the resistance to arbekacin. Thin-layer chromatography revealed that AAC(6′)-Iaj acetylated all aminoglycosides tested except gentamicin. These findings indicated that AAC(6′)-Iaj is a functional acetyltransferase that modifies the amino groups at the 6′ positions of aminoglycosides and contributes to aminoglycoside resistance of P. aeruginosa NCGM1588, including arbekacin.