Koji Morita

Kyorin University, Edo, Tōkyō, Japan

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Publications (21)31.39 Total impact

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    ABSTRACT: A novel gene, bla KHM-1, encoding a metallo-β-lactamase, KHM-1, was cloned from a clinical isolate of Citrobacter freundii resistant to most β-lactam antibiotics. Escherichia coli expressing bla KHM-1 was resistant to all broad-spectrum β-lactams except for monobactams and showed reduced susceptibility to carbapenems. Recombinant KHM-1 exhibited EDTA-inhibitable hydrolytic activity against most β-lactams, with an overall preference for cephalosporins. Copyright © 2008, American Society for Microbiology. All Rights Reserved.
    Antimicrobial Agents and Chemotherapy 10/2008; 52(11):4194-7. DOI:10.1128/AAC.01337-07 · 4.45 Impact Factor
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    ABSTRACT: Resistance of Mycobacterium tuberculosis to pyrazinamide (PZA) derives mainly from mutations in the pncA gene. We developed a reverse hybridization-based line probe assay with oligonucleotide probes designed to detect mutations in pncA. The detection of PZA resistance was evaluated in 258 clinical isolates of M. tuberculosis. The sensitivity and specificity of PZA resistance obtained by this new assay were both 100%, consistent with the results of conventional PZA susceptibility testing. This assay can be used with sputa from tuberculosis patients. It appears to be reliable and widely applicable and, given its simplicity and rapid performance, will be a valuable tool for diagnostic use.
    Journal of Clinical Microbiology 10/2007; 45(9):2802-7. DOI:10.1128/JCM.00352-07 · 4.23 Impact Factor
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    ABSTRACT: We developed a DNA sequencing-based method to detect mutations in the genome of drug-resistant Mycobacterium tuberculosis. Drug resistance in M. tuberculosis is caused by mutations in restricted regions of the genome. Eight genome regions associated with drug resistance, including rpoB for rifampin (RIF), katG and the mabA (fabG1)-inhA promoter for isoniazid (INH), embB for ethambutol (EMB), pncA for pyrazinamide (PZA), rpsL and rrs for streptomycin (STR), and gyrA for levofloxacin, were amplified simultaneously by PCR, and the DNA sequences were determined. It took 6.5 h to complete all procedures. Among the 138 clinical isolates tested, 55 were resistant to at least one drug. Thirty-four of 38 INH-resistant isolates (89.5%), 28 of 28 RIF-resistant isolates (100%), 15 of 18 EMB-resistant isolates (83.3%), 18 of 30 STR-resistant isolates (60%), and 17 of 17 PZA-resistant isolates (100%) had mutations related to specific drug resistance. Eighteen of these mutations had not been reported previously. These novel mutations include one in rpoB, eight in katG, one in the mabA-inhA regulatory region, two in embB, five in pncA, and one in rrs. Escherichia coli isolates expressing individually five of the eight katG mutations showed loss of catalase and INH oxidation activities, and isolates carrying any of the five pncA mutations showed no pyrazinamidase activity, indicating that these mutations are associated with INH and PZA resistance, respectively. Our sequencing-based method was also useful for testing sputa from tuberculosis patients and for screening of mutations in Mycobacterium bovis. In conclusion, our new method is useful for rapid detection of multiple-drug-resistant M. tuberculosis and for identifying novel mutations in drug-resistant M. tuberculosis.
    Journal of Clinical Microbiology 02/2007; 45(1):179-92. DOI:10.1128/JCM.00750-06 · 4.23 Impact Factor
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    ABSTRACT: Strains of the multidrug-resistant (MDR) Salmonella enterica serovar Typhimurium isolated in Japan were examined for high-level fluoroquinolone resistance. Since the first isolation in 2000 (described in reference 13), we have identified 12 human and 5 nonhuman isolates with high-level fluoroquinolone-resistance (ciprofloxacin MIC of 24 microg/ml or more). Most of these isolates shared some features including definitive phage type (DT 12/193), resistance type (ACSSuTNCp; resistant to ampicillin, chloramphenicol, streptomycin, sulfonamides, tetracycline, nalidixic acid, and ciprofloxacin), and genotype on pulsed-field gel electrophoresis that were different from those of the MDR S. enterica Typhimurium DT 104. Mutations in quinolone resistance-determining regions of gyrA and parC were also conserved in almost all of the isolates despite the absence of any apparent epidemiological relationships among cases. This suggests that a specific clonal group of the serovar Typhimurium with high levels of fluoroquinolone resistance is disseminating among animals and humans in Japan.
    Journal of Clinical Microbiology 11/2005; 43(10):5074-9. DOI:10.1128/JCM.43.10.5074-5079.2005 · 4.23 Impact Factor
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    ABSTRACT: A novel gene, dfrG, encoding a trimethoprim (TMP)-resistant dihydrofolate reductase (DHFR, designated S3DHFR) was cloned from a clinical isolate of methicillin-resistant Staphylococcus aureus. Escherichia coli expressing dfrG was highly resistant to TMP. Recombinant S3DHFR exhibited DHFR activity that was not inhibited by TMP.
    Antimicrobial Agents and Chemotherapy 10/2005; 49(9):3948-51. DOI:10.1128/AAC.49.9.3948-3951.2005 · 4.45 Impact Factor
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    ABSTRACT: We characterized multidrug-resistant Pseudomonas aeruginosa strains isolated from patients involved in an outbreak of catheter-associated urinary tract infections that occurred in a neurosurgery ward of a hospital in Sendai, Japan. Pulsed-field gel electrophoresis of SpeI-, XbaI-, or HpaI-digested genomic DNAs from the isolates revealed that clonal expansion of a P. aeruginosa strain designated IMCJ2.S1 had occurred in the ward. This strain possessed broad-spectrum resistance to aminoglycosides, beta-lactams, fluoroquinolones, tetracyclines, sulfonamides, and chlorhexidine. Strain IMCJ2.S1 showed a level of resistance to some kinds of disinfectants similar to that of a control strain of P. aeruginosa, ATCC 27853. IMCJ2.S1 contained a novel class 1 integron, In113, in the chromosome but not on a plasmid. In113 contains an array of three gene cassettes of bla(IMP-1), a novel aminoglycoside resistance gene, and the aadA1 gene. The aminoglycoside resistance gene, designated aac(6')-Iae, encoded a 183-amino-acid protein that shared 57.1% identity with AAC(6')-Iq. Recombinant AAC(6')-Iae protein showed aminoglycoside 6'-N-acetyltransferase activity by thin-layer chromatography. Escherichia coli expressing exogenous aac(6')-Iae showed resistance to amikacin, dibekacin, isepamicin, kanamycin, netilmicin, sisomicin, and tobramycin but not to arbekacin, gentamicins, or streptomycin. Alterations of gyrA and parC at the amino acid sequence level were detected in IMCJ2.S1, suggesting that such mutations confer the resistance to fluoroquinolones observed for this strain. These results indicate that P. aeruginosa IMCJ2.S1 has developed multidrug resistance by acquiring resistance determinants, including a novel member of the aac(6')-I family and mutations in drug resistance genes.
    Antimicrobial Agents and Chemotherapy 10/2005; 49(9):3734-42. DOI:10.1128/AAC.49.9.3734-3742.2005 · 4.45 Impact Factor
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    ABSTRACT: A shiga toxin-producing Escherichia coli (STEC) O26 strain resistant to cefotaxime (CTX) and cefpodoxime (but not ceftazidime) was isolated from the faecal sample of a 17-year-old outpatient with diarrhea. The double disk synergy test, twin test, polymerase chain reaction and sequence analysis confirmed that the strain produced CTX-M-3 type extended-spectrum beta-lactamase (ESBL). Conjugation experiment results suggested that the CTX resistance in this strain was determined by an approximately 85kbp plasmid that was readily transferable to a susceptible recipient E. coli strain. This is the first report from Japan of CTX-M-3type ESBL-producing STEC O26.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 04/2005; 79(3):161-8. DOI:10.11150/kansenshogakuzasshi1970.79.161
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    ABSTRACT: DNA fragments were amplified by PCR from all tested strains of Aeromonas hydrophila, A. caviae, and A. sobria with primers designed based on sequence alignment of all lipase, phospholipase C, and phospholipase A1 genes and the cytotonic enterotoxin gene, all of which have been reported to have the consensus region of the putative lipase substrate-binding domain. All strains showed lipase activity, and all amplified DNA fragments contained a nucleotide sequence corresponding to the substrate-binding domain. Thirty-five distinct nucleotide sequence patterns and 15 distinct deduced amino acid sequence patterns were found in the amplified DNA fragments from 59 A. hydrophila strains. The deduced amino acid sequences of the amplified DNA fragments from A. caviae and A. sobria strains had distinctive amino acids, suggesting a species-specific sequence in each organism. Furthermore, the amino acid sequence patterns appear to differ between clinical and environmental isolates among A. hydrophila strains. Some strains whose nucleotide sequences were identical to one another in the amplified region showed an identical DNA fingerprinting pattern by repetitive extragenic palindromic sequence-PCR genotyping. These results suggest that A. hydrophila, and also A. caviae and A. sobria strains, have a gene encoding a protein with lipase activity. Homologs of the gene appear to be widely distributed in Aeromonas strains, probably associating with the evolutionary genetic difference between clinical and environmental isolates of A. hydrophila. Additionally, the distinctive nucleotide sequences of the genes could be attributed to the genotype of each strain, suggesting that their analysis may be helpful in elucidating the genetic heterogeneity of Aeromonas.
    Applied and Environmental Microbiology 02/2004; 70(1):145-51. DOI:10.1128/AEM.70.1.145-151.2004 · 3.95 Impact Factor
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    ABSTRACT: Drug resistance trends were investigated for 271 Vibrio cholerae O1 (V.c O1) and 401 V. cholerae non-O1 (V.c non-O1) strains isolated from mainly imported diarrheal cases during 1981-2001 in Japan. The results of drug resistance test using 8 drugs (CP, TC, SM, KM, ABPC, ST, NA, and NFLX) showed that 34.7% of the V. c O1 strains and 15.7% of V.c non-O1 strains were multi-drug or mono-drug resistant. The incidence of drug resistant strains has increased since 1991, and it has been remarkable in V.c O1 strains that increased from 1.2% in 1981-1985 to 70.8% in 1996-2001. The drug resistance patterns of the resistant strains classified into 6 types in V.c O1 and 21 types in V.c non-O1. The prevalent patterns recognized were SM (75.5%), CP.TC.SM.ST (10.6%) and CP.SM.ST (8.5%) in V.c O1, and SM (25.4%) and ABPC (25.4%) in V.c non-O1. Ten V.c O1 strains (3.7%) and 10 V.c non-O1 strains (2.5%) were multi-drug resistant including TC. Among those, 13 strains were isolated from travelers who returned to Japan from Thailand. One V.c O1 strain (0.4%) and 6 V.c non-O1 strains (1.5%) were NA high-resistant and fluoroquinolones low-sensitive. Among those, 4 strains were isolated from travelers who returned to Japan from India.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 05/2003; 77(4):195-202. DOI:10.11150/kansenshogakuzasshi1970.77.195
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    ABSTRACT: We investigated the effectiveness of fosfomycin combined with other antibiotics, such as piperacillin, cefepime, ceftazidime, imipenem, meropenem, aztreonam, gentamicin, or levofloxacin, against 30 Pseudomonas aeruginosa strains, including multidrug-resistant strains, isolated from clinical specimens, using the efficacy time index (ETI) assay. The assay refers to the result of pharmacokinetics obtained from adult men volunteers, and yields an ETI to evaluate the effect of a combination of antimicrobial agents. With the ETI, based on serum concentration 3 h after the administration of two antimicrobial agents, the effectiveness of antimicrobial combinations was evaluated as follows: poor, ETI < 0.5; fair, 0.5 < or = ETI < 1; good, 1 < or = ETI < 8; and excellent, ETI > or = 8. The combination of fosfomycin and cefepime (efficacy rate [excellent plus good], 76.7%) and fosfomycin/aztreonam (efficacy rate, 76.7%) appeared to be the most effective, followed by fosfomycin/meropenem (efficacy rate, 76.6%), fosfomycin/imipenem (efficacy rate, 73.3%), fosfomycin/ceftazidime (efficacy rate, 70%), fosfomycin/gentamicin (efficacy rate, 70%), fosfomycin/piperacillin (efficacy rate, 66.7%), and fosfomycin/levofloxacin (efficacy rate, 66.7%). Fosfomycin/cefepime, fosfomycin/aztreonam, and fosfomycin/meropenem may be clinically useful in selected patients, particularly for P. aeruginosa. The ETI assay provided information on the minimum inhibitory concentration (MIC) of many pairs of combined antimicrobial agents simultaneously. The ETI assay may be a useful technique with which to investigate the effect of combinations of antimicrobial agents against P. aeruginosa, including multidrug-resistant strains.
    Journal of Infection and Chemotherapy 04/2002; 8(1):37-42. DOI:10.1007/s101560200004 · 1.38 Impact Factor
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    ABSTRACT: Drug resistance trends were investigated for 1,318 enterotoxigenic Escherichia coli (ETEC) isolated from overseas traveler's diarrheal cases in Tokyo during 1988-1999. A total of 1.6% (21 strains) were nalidixic-acid resistant and fluoroquinolones (NFLX, OFLX, CPFX, LVFX, TFLX, SPFX; FQ) low-sensitive (or low-level-resistant). None of the strains were high-level-resistant to FQ. The FQ low-sensitive strains were isolated in 1996 for the first time, and increased from 3.4% in 1996 to 15.8% in 1999. Countries visited by travelers with the FQ low-sensitive ETEC were India (16 cases), Nepal (3 cases), Cambodia (1 case), and Egypt (1 case). Drug resistance-patterns of the FQ low-sensitive strains, including other drugs (CP, TC, SM, KM, ABPC, ST, NA, and FOM) tested, varied among the 6 types. Among those, multidrug resistant strains accounted for 57.1% (12 strains). The enterotoxin producing types of strains were LT (4 strains), ST (10 strains), and both (7 strains). The serotypes of the strains were classified into 16 types. The quinolone resistance determining regions (QRDRs) of the gyrA genes of the FQ low-sensitive strains were sequenced. The mutations of a Ser to a Leu at position 83 (Ser-83-->Leu) was found in 19 strains, and Asp-87-->Tyr was found in 2 strains.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 09/2001; 75(9):785-91. DOI:10.11150/kansenshogakuzasshi1970.75.785
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    ABSTRACT: A total of 118 nalidixic-acid (NA)-resistant Salmonella strains consisting of 68 domestic strains and 50 imported strains isolated during 1988-1998 in Tokyo were examined regarding their annual incidence, serovars, drug-resistance patterns, and minimum inhibitory concentrations(MIC) to fluoroquinolones (NFLX, OFLX, ENX, and CPFX). NA-resistant strains accounted for 1.3% of all Salmonella (5,302 strains) isolated from domestic cases, and 2.5% of all Salmonella (1,981 strains) isolated from imported cases. The incidence of NA-resistant strains has increased since 1995, and it has been remarkable in imported cases. The results of the serotyping showed that the NA-resistant strains were classified into 25 serovars, excluding untypable strains. Among those, S. Enteritidis (21 strains), S. Blockley (13 strains), S. Litchifield (13 strains), S. Typhimurium (13 strains), S. Hadar (9 strains), and S. Virchow (8 strains) were predominant. Drug-resistance patterns of NA-resistant strains, including other drugs (CP, TC, SM, KM, ABPC, ST, FOM, and NFLX) tested varied among the 26 types. Among those, multidrug-resistant strains accounted for 61.9% (73 strains), and one strain among them was high-resistant to NFLX. MIC distribution of NA-resistant strains to fluoroquinolones showed that the ranges of all drugs were 4-128 times higher than NA-sensitive strains used for controls.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 05/2000; 74(4):345-52. DOI:10.11150/kansenshogakuzasshi1970.74.345
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    ABSTRACT: One hundred fifty-one O serotypable Escherichia coli strains which were assumed diarrheogenic E. coli among 2,240 strains of E. coli isolated from the in- and outpatients stools with or without gastrointestinal symptoms at Kyorin University Hospital from February 1994 to September 1996 were examined for the relationship between the possession of eight pathogenic factor-related genes and gastrointestinal symptoms of the patients using the polymerase chain reaction (PCR) for these strains. The rate of possession of pathogenic factor-related genes in the E. coli examined was 20.5% (31 strains) and gastrointestinal symptoms were found in all the patients with these strains except one. In the patients without gastrointestinal symptoms, E. coli isolates that possesses these genes was detected in only one case during 61 cases. The respective genes detected were eaeA and astA in each 14 strains, VT1 in 6, VT2 in 5, ST1b in 4, aggR in 3 and LT in 2, ST1a and invE gene was not detected. In particular, the O157 strains were found in 55.6% (5/9 strains) for these genes, and individual strains had VT1, VT2, eaeA and astA genes simultaneously. In contrast, none of these related genes was found in 9 strains of enteroinvasive serotype but enteropathogenic E. coli-related genes were found in 3 strains. The rate of possession of the genes related to enterotoxigenic E. coli, O159 which was most frequently isolated was low as 2.3% (1/43 strains, astA gene) and there were strains showing low correlation to the state of possession of the genes with the O serotype. Since the prevalence of the gastrointestinal symptoms is clearly high for the case which possesses the strain of which the pathogenic factor-related gene was detected, it was suggested that detection of pathogenic factor-related genes in E. coli isolates from feces using the PCR could be an effective means to decide whether the bacteria concerned was a causal bacteria or not in clinical practice.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 05/2000; 74(4):372-7. DOI:10.11150/kansenshogakuzasshi1970.74.372
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    ABSTRACT: A total of 341 Shigella sonnei strains consisting of 94 domestic strains and 247 imported strains isolated during 1990-1997 in Tokyo, were examined regarding their colicine-type, drug-resistance and ornithine-utilization. The colicine typing results showed that the domestic strains were classified into 7 types, and the imported strains were classified into 13 types. Among the colicine-types identified, 8-type, 0-type, 6-type and 12-type were predominant in the domestic strains, whereas 6-type, 0-type, 8-type, 9A-type and 12-type were predominant in the imported strains. The drug-resistance test using 9 drugs (CP, TC, SM, KM, ABPC, ST, NA, FOM and NFLX) showed that 89.4% of the domestic strains and 85.4% of the imported strains were resistant to some of the drugs except FOM and NFLX. Drugs with a high resistant rate were SM, TC and ST for both groups. Drug-resistance patterns of the resistant strains varied in 22 types. Among those, a triple drug-resistance type with TC.SM.ST was found in the most frequent pattern in both groups. The results of the ornithine-utilization test revealed that 28.7% of the domestic strains and 8.1% of the imported strains were negative. The ornithine-negative strains in the same source had a similar plasmid-profile, but generally there was no correlation between the different sources.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 06/1999; 73(5):414-20. DOI:10.11150/kansenshogakuzasshi1970.73.414
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    ABSTRACT: Strains of Burkholderia cepacia isolated in our hospital from November 1995 to September 1996 were classified with randomly amplified polymorphic DNA-PCR (RAPD-PCR) and conventional biochemical tests (ID test.NF-18, API20NE, and Neg Combo 4J kit), and intrahospital isolates of B. cepacia were analysed. During the period 28 strains from inpatients and 2 from medical apparatus were isolated. Twenty four of 28 (85.7%) were from sputum. In 1996 from January to February, 20 strains were detected from 8 inpatients, and two strains were from the nebulizers at the Trauma and Critical Care Center (TCC). With typing of B. cepacia by conventional methods no epidemiological relations among isolates were found. However, DNA patterns of original isolates from the nebulizers at TCC by RAPD-PCR were identical with those of isolates in sputa from patients in other wards who had stayed at TCC, indicating that TCC was an initial source of transmission and the strain was transmitted with the patients to the wards. These results suggest that RAPD-PCR method might be a useful tool to analyse an epidemiological survey for intrahospital transmission of isolate.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 08/1998; 72(7):688-93. DOI:10.11150/kansenshogakuzasshi1970.72.688
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    ABSTRACT: Five Shigella strains isolated from stool cultures of imported diarrheal cases in Japan, did not react to any antisera of the established Shigella serovars. These strains had the typical biochemical characteristics of Shigella dysenteriae, and were biochemically identical. All strains were positive in the Sereny test and other tests for invasivness; these indicate that they can cause shigellosis in humans. The results of antigenic analysis revealed that they did not belong to any of the recognized or provisional serovars, and were serologically indistinguishable. They had the same drug-resistance pattern (CP.TC.SM.ABPC.ST) and plasmid-profile. Strain 96-204 is designated as the test strain for this new serovar.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 06/1998; 72(5):499-503. DOI:10.11150/kansenshogakuzasshi1970.72.499
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    ABSTRACT: In 1996, we examined five domestic and eight imported cases of sporadic diarrhea caused by Vibrio cholerae non-O1 in Tokyo. The domestic cases occurred during the summer, from June to September, while the imported cases were seen throughout the year. The major clinical symptoms of the patients were watery diarrhea (100%) with an average frequency of 5.5 times/day, abdominal pain (77%), vomiting (31%) and fever (15%). A total of 13 strains isolated from these 13 cases had the typical biochemical characteristics of Vibrio cholerae, and were classified into 11 kinds of serovars (O2, O5, O8, O9, O12, O14, O27, O51, O88, O97, and O161). All strains produced hemolysin, and two strains produced NAG-ST, while no strain produced cholera toxin.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 01/1998; 71(12):1204-9. DOI:10.11150/kansenshogakuzasshi1970.71.1204
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    ABSTRACT: The hemolysin of Aeromonas sobria is one of the important virulence factors in this organism. Rapid detection and identification test for A. sobria is important for early and specific diagnosis of this infectious disease. We evaluated the polymerase chain reaction (PCR) for the rapid detection of A. sobria. Two pairs of synthetic oligonucleotide primers (ASA1-s and a; AerAAS-s and a) were used in PCR technique to detect the different hemolysin genes (ASA1 and aerAAS) in A. sobria. The PCR identified 91% of ASA1-positive and 23.4% of aerAAS-positive strains in beta-hemolytic A. sobria. Other species of Aeromonas, Plesiomonas shigelloides, Vibrio cholerae O1 and V. parahaemolyticus tested were negative in the PCR with two pairs of primers. The PCR technique for detection of two hemolysin genes suggested the possibility of application of this method for detection of A. sobria in A. sobria-associated infections.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 01/1997; 70(12):1266-70. DOI:10.11150/kansenshogakuzasshi1970.70.1266
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    ABSTRACT: A total of 182 isolates of motile Aeromonas from patients with diarrhea and environmental sources was investigated for hemolytic activity to rabbit erythrocyte and cytotoxicity to HeLa 229 cell. Furthermore, the relation between O serogroup and virulence factors, which were lethal to mouse and autoagglutination, were investigated. There were many strains possessing both the hemolytic and cytotoxic activities in A. hydrophila from overseas traveller's diarrhea, suggesting that these activities were associated with intestinal pathogenecity. Although there was a clear correlation between hemolytic and cytotoxic activities in A. hydrophila from overseas traveller's diarrhea, the correlation was not found in A. hydrophila from domestic cases of diarrhea and A. sobria from overseas traveller's diarrhea. Especially, some A. hydrophila isolates from domestic case of diarrhea produced only hemolysin. These results indicated that there was a difference in specificity between the toxins accounted for hemolytic and cytotoxic activities, and more than two different toxins were developed. O serogroups 11, 34, 14, 16, and 35 in that order were the most frequent serogroups. About half of O11 and O34 strains possessed lethal activity to mouse. Autoagglutination phenomenon did not seem to be associated with the lethal activity. In O11 strains, high cytotoxic titer was more frequently found in lethal activity positive-strains than in the activity negative-strains, suggesting that cytotoxicity contributed preferentially to lethal activity to mouse. But such a correlation was not found in O34 strains, so other virulence factors than hemolysin and cytotoxin may be associated with the lethal activity.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 03/1992; 66(2):127-34. DOI:10.11150/kansenshogakuzasshi1970.66.127
  • Koji Morita · Noboru Watanabe · Masato Kanamori
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    ABSTRACT: A total of 174 Aeromonas isolates consisting of 100 strains from patients with diarrhea being mainly overseas travellers nd healthy subjects, and 74 strains from environmental sources including foods, fish, fresh water, sea water and river soil collected in the area of Tokyo Metropolis and Kanagawa Prefecture was examined for the antimicrobial resistance, presence of plasmids and hemolytic activity. Almost all the isolates (99.4%) were resistant to aminobenzyl penicillin. The isolation frequency of chloramphenicol- or tetracycline-resistant strain was low. Most environmental isolates of A. hydrophila were resistant to multiple antimicrobial agents. Thirty-seven percent of environmental isolates and 39% of human fecal ones carried plasmids. In environmental isolates, seven A. hydrophila and three A. sobria strains carried 63- to 150-kilobase pair (kb) conjugative R plasmids. Two A. hydrophila strains from both the healthy subject and domestic case with diarrhea carried 58- to 90-kb conjugative R plasmids, respectively. None of the isolates from the feces of overseas traveller's diarrhea carried the plasmid. Irrespective of the sources. A. hydrophila showed the highest hemolytic activity among three Aeromonas species. Eighty percent or more of A. hydrophila isolates were of hemolysin positive. The hemolytic titer of A. hydrophila strains from human feces was higher than that of the strains from environmental sources.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 07/1990; 64(6):715-24. DOI:10.11150/kansenshogakuzasshi1970.64.715

Publication Stats

329 Citations
31.39 Total Impact Points

Institutions

  • 2004–2008
    • Kyorin University
      • • School of Health Sciences
      • • Department of Microbiology
      Edo, Tōkyō, Japan
  • 2003
    • Tokyo Metropolitan Institute of Public Health
      Edo, Tōkyō, Japan