Teruo Kirikae

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.

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.

Emergence of 16S rRNA methylase-producing Acinetobacter baumannii and Pseudomonas aeruginosa isolates in hospitals in Vietnam.

Background16S rRNA methylase-producing Gram-negative bacteria are highly resistant to all clinically important aminoglycosides. We analyzed clinical strains of 16S rRNA methylase-producing Acinetobactor baumannii and Pseudomonas aeruginosa obtained from clinical isolates in medical settings in Vietnam.MethodsFrom 2008 to 2011, 101 clinical strains of A. baumannii and 15 of P. aeruginosa were isolated from patients in intensive care units (ICUs) in two medical settings in Vietnam. Antimicrobial susceptibilities were determined using the microdilution method and epidemiological analysis was performed by pulsed-field gel electrophoresis and MLST. Genes encoding the 16S rRNA methylases, OXAs and CTX-Ms were analyzed by PCR and sequence analysis.Results16S rRNA methylase-producing Gram-negative pathogens were detected in two hospitals in Vietnam. Of the 101 clinical isolates of A. baumannii and the 15 of P. aeruginosa isolated from two ICUs in these hospitals, 72 (71.3%) were highly resistant to amikacin, arbekacin and gentamicin, with MICs greater than 1,024xa0mg/L. The 16S rRNA methylases ArmA and RmtB were produced by 61 and 9 isolates of A. baumannii, respectively, and RmtB was produced by 2 isolates of P. aeruginosa. Moreover, 52 of the A. baumannii isolates producing 16S rRNA methylases harbored both blaOXA-23-like and blaOXA-51-like genes. Most A. baumannii isolates producing 16S rRNA methylase obtained in hospital A in Hanoi were ST91 and ST231, whereas most from hospital B in Ho Chi Minh City were ST136, ST195, and ST254.The two P. aeruginosa isolates harboring rmtB showed different patterns on PFGE, one each corresponding to ST217 and ST313.ConclusionsGram-negative bacteria producing the 16S rRNA methylases ArmA and RmtB are emerging in medical settings in Vietnam. A. baumannii isolates in northern and southern regions of Vietnam may be of different lineages.

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

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.

NDM-1 Metallo-β-Lactamase and ArmA 16S rRNA methylase producing Providencia rettgeri clinical isolates in Nepal

BackgroundDrug-resistant Providencia rettgeri producing metallo-β-lactamase and 16S rRNA methylase has been reported in several countries. We analyzed P. rettgeri clinical isolates with resistance to carbapenems and aminoglycosides in a hospital in Nepal.MethodsFive clinical isolates of multidrug-resistant P. rettgeri were obtained in a hospital in Nepal. Antimicrobial susceptibilities were determined using the microdilution method and entire genomes were sequenced to determine drug-resistant genes. Epidemiological analysis was performed by pulsed-field gel electrophoresis.ResultsFour of the 5 isolates were resistant to carbapenems (imipenem and meropenem), with MICs ≥16xa0mg/L, with the remaining isolate showing intermediate resistance to imipenem, with an MIC of 2xa0mg/L and susceptibility to meropenem with an MIC ≤1xa0mg/L. All 5 isolates had blaVEB-1. Of the 4 carbapenem-resistant strains, 3 had blaNDM-1 and 1 had blaOXA-72. All isolates were highly resistant to aminoglycosides (MICs ≥1,024xa0mg/L) and harbored armA. As the result of pulsed-field gel electrophoresis pattern analysis in the 5 P. rettgeri isolates, 4 had identical PFGE patterns and the fifth showed 95.7% similarity.ConclusionsThis is the first report describing multidrug-resistant P. rettgeri strains harboring blaNDM-1 or blaOXA-72 and armA isolated from patients in Nepal.

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.

Emergence of a colistin-resistant Escherichia coli clinical isolate harboring mcr-1 in Japan

The mcr-1 is a gene encoding a phosphoethanolamine transferase, which confers resistance to colistin by transferring phosphoethanolamine to lipid A. We describe here the emergence of a colistin-resistant Escherichia coli clinical isolate harboring plasmid-mediated mcr-1 in Japan. The isolate belonged to ST5702 and is suspected to come from livestock and transmitted to human. This is the first report of a clinical isolate harboring mcr-1 in Japan.

Development of an immunochromatographic assay for rapid detection of AAC(6′)-Ib-producing Pseudomonas aeruginosa

To detect aminoglycoside 6-N-acetyltransferase-Ib [AAC(6)-Ib]-producing, Pseudomonas aeruginosa isolates which are a frequent cause of nosocomial infections in Japan, an immunochromatographic assay was developed using two kinds of monoclonal antibodies (mAbs) recognizing AAC(6)-Ib. The results of the assessment were fully consistent with those of aac(6)-Ib PCR analyses.