Masaru Komatsu

Tenri Yorozu Hospital, Tenri, Nara, Japan

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Publications (25)22.1 Total impact

  • Article: Epidemiology of Escherichia coli, Klebsiella species, and Proteus mirabilis strains producing extended-spectrum β-lactamases from clinical samples in the Kinki Region of Japan.
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    ABSTRACT: In the present study, nonduplicate, clinical isolates of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli, Klebsiella spp, and Proteus mirabilis were collected during a 10-year period from 2000 to 2009 at several hospitals in the Kinki region, Japan. The detection rate of E coli markedly increased from 0.24% to 7.25%. The detection rate of Klebsiella pneumoniae increased from 0% to 2.44% and that of P mirabilis from 6.97% to 12.85%. The most frequently detected genotypes were the CTX-M9 group for E coli, the CTX-M2 group for K pneumoniae, and the CTX-M2 group for P mirabilis. E coli clone O25:H4-ST131 producing CTX-M-15, which is spreading worldwide, was first detected in 2007. The most common replicon type of E coli was the IncF type, particularly FIB, detected in 466 strains (69.7%). Of the K pneumoniae strains, 47 (55.3%) were of the IncN type; 77 P mirabilis strains (96.3%) were of the IncT type. In the future, the surveillance of various resistant bacteria, mainly ESBL-producing Enterobacteriaceae, should be expanded to prevent their spread.
    American Journal of Clinical Pathology 04/2012; 137(4):620-6. · 2.60 Impact Factor
  • Article: [Molecular analysis of the antimicrobial resistant bacteria].
    Noriyuki Abe, Masaru Komatsu
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    ABSTRACT: The antimicrobial susceptibility test is generally performed in clinical laboratories for detecting antimicrobial resistant bacteria. In contrast, the molecular tests include many investigative factors, they are not performed in many clinical laboratories routinely. If it is intimately related to the choice of the antimicrobial agents, it should be introduced as a routine clinical laboratory test. This test is also useful for conducting active surveillance and investigating the cause and occurrence of nosocomial infections.
    Nippon rinsho. Japanese journal of clinical medicine 02/2012; 70(2):283-8.
  • Article: [Surveillance of antimicrobial activity of Pseudomonas aeruginosa isolated in the Kinki district].
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    ABSTRACT: The antimicrobial activity of 18 antimicrobial agents were measured for the 500 Pseudomonas aeruginosa strains that had been isolated from various clinical specimens in 17 medical institutions in the Kinki district from April to July of 2008. The antimicrobial activity was excellent in the order of tobramycin (TOB), arbekacin (ABK), doripenem (DRPM), gentamicin (GM) and amikacin (AMK). Susceptible rate that was interpreted by Clinical and Laboratory Standards Institute (CLSI) was high in the order of AMK, TOB, tazobactam/piperacillin (TAZ/PIPC), DRPM, ABK. Also, the difference in susceptible rate was observed between departments, materials and institutions. Multidrug resistant strains were only 12 (2.4%) but strains that had resistance to 2 agents were 48 (9.6%), therefore, implementation of further surveillance should be continued.
    The Japanese journal of antibiotics 12/2011; 64(6):367-81.
  • Article: [Advantages and disadvantages of outsourcing hospital microbiological testings].
    Masaru Komatsu
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    ABSTRACT: In Japan, laws and ordinances were enforced to relax the regulation of the clinical laboratory setting in hospitals by revising the law of medical institutions in 2001. For this reason, outsourcing hospital microbiological testing, particularly by medium- or small-sized hospitals, was encouraged. The advantage of outsourcing microbiological testing is promotion of an efficient hospital management by cost saving. In contrast, the disadvantages are as follows: deterioration of specimen quality by extension of transportation time, delay in reporting by an independent laboratory compared with that by a hospital-based laboratory; this report is generally obtained within 1 or 2 days, difficulty and lack of communication between the laboratory staff and physician, and deterioration of the value of the microbiology report and the quality of the infection control system in a hospital. In addition to performing profit-related maintenance, independent laboratories should strive hard to maintain the same quality as that of a laboratory registered in a hospital. Furthermore, the new role of independent laboratories demands them to have a system allowing instant communication of information regarding the crisis control of infectious diseases to a hospital.
    Rinsho byori. The Japanese journal of clinical pathology 10/2011; 59(10):944-6.
  • Article: [Surveillance of nalidixic acid-resistant and extended-spectrum beta-lactamase-producing Salmonella spp. isolated from human feces].
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    ABSTRACT: Nalidixic acid (NA)-resistant and extended-spectrum beta-lactamase (ESBL)-producing Salmonella sp. isolates from human specimens are associated with clinical failure or delayed response in subjects treated with fluoroquinolone or third-generation cephalosporins. We studied drug susceptibility in 604 Salmonella enterica isolates from human feces in 2007. Of these, 39 (6.5%) were resistat to NA. Of these, 46% were resistant to two or more drugs and 2% susceptible to NA were resistant to multiple drugs (p < 0.001). Three ESBL-producing Salmonella sp. isolated were of the CTX-M family gene type. One strain of plasmid-mediated AmpC beta-lactamase belonged to the CMY-2 family gene type. Our results thus showed that NA-resistant isolates were resistant to antimicrobial agents and confirmed the presence of a small number of isolates producing ESBL and AmpC beta-lactamase.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 07/2011; 85(4):355-9.
  • Article: Laboratory surveillance for prospective plasmid-mediated AmpC beta-lactamases in the Kinki region of Japan.
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    ABSTRACT: Extended-spectrum beta-lactamases, plasmid-mediated AmpC beta-lactamases (PABLs), and plasmid-mediated metallo-beta-lactamases confer resistance to many beta-lactams. In Japan, although several reports exist on the prevalence of extended-spectrum beta-lactamases and metallo-beta-lactamases, the prevalence and characteristics of PABLs remain unknown. To investigate the production of PABLs, a total of 22,869 strains of 4 enterobacterial species, Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca, and Proteus mirabilis, were collected during six 6-month periods from 17 clinical laboratories in the Kinki region of Japan. PABLs were detected in 29 (0.13%) of 22,869 isolates by the 3-dimensional test, PCR analysis, and DNA sequencing analysis. PABL-positive isolates were detected among isolates from 13 laboratories. Seventeen of 13,995 (0.12%) E. coli isolates, 8 of 5,970 (0.13%) K. pneumoniae isolates, 3 of 1,722 (0.17%) K. oxytoca isolates, and 1 of 1,182 (0.08%) P. mirabilis isolates were positive for PABLs. Of these 29 PABL-positive strains, 20 (69.0%), 6 (20.7%), 2 (6.9%), and 1 (3.4%) carried the genes for CMY-2, DHA-1, CMY-8, and MOX-1 PABLs, respectively. Pattern analysis of randomly amplified polymorphic DNA and pulsed-field gel electrophoretic analysis revealed that the prevalence of CMY-2-producing E. coli strains was not due to epidemic strains and that 3 DHA-1-producing K. pneumoniae strains were identical, suggesting their clonal relatedness. In conclusion, the DHA-1 PABLs were predominantly present in K. pneumoniae strains, but CMY-2 PABLs were predominantly present in E. coli strains. The present findings will provide significant information to assist in preventing the emergence and further spread of PABL-producing bacteria.
    Journal of clinical microbiology 09/2010; 48(9):3267-73. · 4.16 Impact Factor
  • Article: Monte Carlo simulation for evaluation of the efficacy of carbapenems and new quinolones against ESBL-producing Escherichia coli.
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    ABSTRACT: Extended-spectrum beta-lactamase (ESBL)-producing bacteria are known to be resistant to penicillins, cephalosporins, and monobactams because of their substrate specificity, and these bacteria are sensitive only to a narrow range of antimicrobial agents. The present study was undertaken to evaluate the efficacy of carbapenems and the new quinolones against ESBL-producing Escherichia coli, using a Monte Carlo simulation based on the pharmacokinetic/pharmacodynamic (PK/PD) theory. The time above MIC (TAM, %) served as the PK/PD parameter for carbapenems, with the target level set at 40%. The AUC/MIC served as the PK/PD parameter for the new quinolones, with the target level set at more than 125. In the analysis of drug sensitivity, the MIC50 of all carbapenems other than imipenem was low (0.03 microg/ml), while the MIC50 of the new quinolones was higher (1-2 microg/ml). The probability of achieving the PK/PD target with carba penems after two doses at the usual dose level, as determined by the Monte Carlo simulation, was high for each of the carbapenems tested (99.0% for biapenem, 99.60% for meropenem, and 95.03% for doripenem), except for imipenem. Among the new quinolones, the highest probability of achieving the PK/PD target was obtained with pazufloxacin (42.90%). Thus, the results of the present study have revealed that carbapenems are effective at the regular dose and can be used as the first-choice antibiotics for ESBL-producing E. coli because the resistance ratios for carbapenems are low compared to those of the new quinolones.
    Journal of Infection and Chemotherapy 03/2009; 15(1):13-7. · 1.80 Impact Factor
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    Article: [In-vitro susceptibilites to levofloxacin and various antibacterial agents of 18,639 clinical isolates obtained from 77 centers in 2004].
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    ABSTRACT: A total of 18,639 clinical isolates in 19 species collected from 77 centers during 2004 in Japan were tested for their susceptibility to fluoroquinolones (FQs) and other selected antibiotics. The common respiratory pathogens, Streptococcus pyogenes, Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae showed a high susceptible rate against FQs. The isolation rate of beta lactamase non-producing ampicillin-resistant H. influenzae was approximately three times as large as those of western countries. Most strains of Enterobacteriaceae were also susceptible to FQs. The resistance rate of Escherichia coli against FQs has however been rapidly increasing so far as we surveyed since 1994. The FQs-resistant rate in methicillin-resistant Staphylococcus aureus (MRSA) showed approximately 90% except for 36%. of sitafloxacin while FQs-resistant rate in methicillin-susceptible S. aureus (MSSA) was around 5%. The FQs-resistant rate of methicillin-resistant coagulase negative Staphylococci (MRCNS) was also higher than that of methicillin-susceptible coagulase negative Staphylococci (MSCNS), however, it was lower than that of MRSA. In Pseudomonas aeruginosa clinical isolates, 32-34% from UTI and 15-19% of from RTI was resistant to FQs. Acinetobacter spp. showed a high susceptibility to FQs. Although FQs-resistant Neisseria gonorrhoeae have not been increased in western countries, it is remarkably high in Japan. In this survey, isolates of approximately 85% was resistant to FQs.
    The Japanese journal of antibiotics 01/2007; 59(6):428-51.
  • Article: [Extended-spectrum-beta-lactamase-producing Proteus mirabilis: laboratory-based surveillance in cooperation with 12 clinical laboratories in the Kinki Region of Japan].
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    ABSTRACT: We studied 247 strains of Proteus mirabilis collected during the 6 months from November 2003 to April 2004 from 12 clinical laboratories in the Kinki region of Japan for the production of extended-spectrum beta-lactamase (ESBL). Eighteen strains (7.3%) showed MICs for cefpodoxime of > or = 2 microg/mL and 13 strains (5.2%) were positive for the double-disk synergy test. Susceptibility depended on genotype. MICs for cefepime, cefozopran, and cefpirome were high (> or = 8 microg/mL), and that for ceftazidime was low (0.12-0.5 microg/mL). Meropenem showed the lowest MIC (< or = 0.03-0.25 microg/mL) of the calbapenems, while other calbapenems showed somewhat higher values (0.5-2 microg/mL). The MIC of tazobactam/piperacillin was also relatively low (< or = 0.25-1 microg/mL). Analysis of the ESBL genotype by the polymerase chain reaction showed that 12 of 13 strains were CTX-M2 types. CTX-M9 was detected in a single laboratory. The clinical background showed 5 strains in urine samples. Twelve of 13 strains were detected in patients with minimal devices use. No symptoms were found in most cases of established syndrome. Analysis of PCR fingerprint profiles of random amplified polymorphic DNA patterns showed that 6 of 7 strains from hospital 1 showed the same pattern, and 5 of 5 strains from hospital 13 showed the same pattern, suggesting the nosocomial spread of P. mirabilis in each hospital.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 05/2006; 80(3):231-7.
  • Article: [Successful treatment of invasive sinus aspergillosis with micafungin and itraconazole].
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    ABSTRACT: We report a case of invasive sinus aspergillosis that extended to the orbital cavity and cavernous sinus and was improved by treatment with micafungin and itraconazole. A 83-year-old woman was referred to our hospital because of headache and impaired of eye movement on the right side. Physical examination revealed impaired function of cranial nerves, II, II, IV, and VI on the right side. MRI showed evidence of inflammation of the right sphenoid sinus and ethmoidal sinus and an enhancing mass in the right cavernous sinus and orbit. Because a culture of a specimen from the right sphenoid sinus extracted during endoscopic sinus surgery, yielede Aspergillus fumigatus, a diagnosed of invasive sinus aspergillosis complicated by cavernous sinus symdrome and orbital apex symdrome was made. It was difficult to completely remove the mass in the sinuses surgically and drug therapy with micafungin was started and then itraconazole was added. The clinical manifestations and the impaired function of cranial nerves II, III, IV, and VI improved, and MRI showed regression of the mass in the sinuses temporary in response to drug therapy. Invasive sinus aspergillosis often progresses rapidly in the absence of surgery. Our case is valuable, because invasive sinus aspergillosis was improved by drug therapy alone, and combined treatment with micafungin and itraconazole was effective.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 04/2006; 80(2):115-8.
  • Article: [Autopsy case of pulmonary aspergillosis soon after convalescence from pulmonary tuberculosis].
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    ABSTRACT: A 70-year-old man with liver cirrhosis and previous gastrectomy admitted for fever, coughing, and bloody sputum soon after convalescing from pulmonary tuberculosis had a peripheral white blood cell count of 9,900/microL, C-reactive protein of 14.1mg/dL, serum albumin of 2.0g/dL, and serum positive for antiaspergillus and beta-D glucan antibodies. Chest radiography showed thickening of the walls of the large residual cavities with previous tuberculosis lesions and infiltrates around them. On day 2 of hospitalization, Aspergillus fumigatus without other bacillus was detected in sputum culture taken on admission. Despite immediate treatment with intravenous micafungin and oral itraconazole and improved brief initial improvement, his general condition abruptly deteriorated into frequent massive hemoptysis and he developed of shock, respiratory failure, and severe malnutrition, dying 30 days later. Autopsy findings showed pulmonary aspergillosis in and around the large cavities and on the other side of the lungs. Pulmonary aspergillosis without hematological malignanciy and immunosuppression can thus be abruptly severe and fatal due to malnourishment stemming from pre-existing conditions such as chronic hepatitis despite prompt, ordinarily adequate medical treatment.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 01/2006; 79(12):957-63.
  • Article: [Nationwide surveillance of parenteral antibiotics containing meropenem activities against clinically isolated strains in 2004].
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    ABSTRACT: The antibacterial activity of meropenem (MEPM) and other parenteral antibiotics against clinical isolates of 907 strains of Gram-positive bacteria, 1790 strains of Gram-negative bacteria, and 192 strains of anaerobic bacteria obtained from 30 medical institutions during 2004 was measured. The results were as follows; 1. MIC90 of MEPM for almost all of enterobacteriaceae and Haemophilus influenzae were 4-fold to 32-fold lower than those of other carbapenems. MEPM was more active than other carbapenem antibiotics against Gram-negative bacteria, especially against enterobacteriaceae and H. influenzae. MEPM were active against most of the species tested in Gram-positive and anaerobic bacteria, except for multi-drug resistant strains including methicillin-resistant Staphylococcus aureus. 2. As for Pseudomonas aeruginosa, imipenem (IPM) showed high cross-resistant rate againt meropenem-resistant P. aeruginosa (87.9%). MEPM showed low cross-resistant rate both againt IPM-resistant P. aeruginosa (49.2%) and ciprofloxacin-resistant P. aeruginosa (38.0%). 3. The proportion of extended-spectrum beta-lactamase (ESBL) strains was 3.1% (4 strains) in Escherichia coli, 8.0% (2 strains) in Citrobacter koseri, 2.5% (3 strains) in Klebsiella pneumoniae, 2.5% (2 strains) in Enterobacter cloacae, 0.9% (1 strains) in Serratia marcescens, and 2.2% (2 strains) in Proteus mirabilis. The proportion of metallo-beta-lactamase strains was 1.6% (5 strains) in P. aeruginosa. 4. Of all species tested, Peptostreptococcus spp. was the only species, which MIC90 of MEPM was more than 4-fold higher than that in our previous study using clinical isolates during 2002 (0.25 microg/ml --> 1 microg/ml). Therefore, there is almost no siginificant decrease in susceptibility of clinical isolates to meropenem. In conclusion, the results from this surveillance study suggest that MEPM retains its potent and broad antibacterial activity and therefore is a clinically useful carbapenem at present, 9 years after available for commercial use.
    The Japanese journal of antibiotics 12/2005; 58(6):655-89.
  • Article: [In vitro activity of antimicrobial agents against clinical isolates of Pseudomonas aeruginosa].
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    ABSTRACT: Two hundred and seven clinical isolates of Pseudomonas aeruginosa were collected at Tenri Hospital between April 2003 and March 2004. We determined the minimum inhibitory concentration (MIC) of 16 antimicrobial agents, including prulifloxacin, pazufloxacin and biapenem which were recently published in Japan, against these isolates according to the guidelines of the Clinical and Laboratory Standards Institute. For the fluoroquinolones, the rank order of activity was prulifloxacin (MIC50, 0.5 microg/ml)>ciprofloxacin (1 microg/ml)> pazufloxacin (2 microg/ml)=levofloxacin (2 microg/ml)>gatifloxacin (4 microg/ml). For the carbapenems, the rank order of activity was meropenem (MIC50, 1 microg/ml)=biapenem (1 microg/ml)>imipenem (2 microg/m)>panipenem (8 microg/ml). For the cephalosporins and monobactam, the overall rank order of activity was cefozopran (MIC50, 4 microg/ml)= ceftazidime (4 microg/ml)>cefepime (8 microg/ml)=piperacillin/tazobactam (8 microg/ml)>aztreonam (16 microg/ml)= cefoperazone/sulbactam (16 microg/ml)=cefpirome (16 microg/ml). The rates of susceptibility to antimicrobial agents as per the criteria of the Japanese Society of Antimicrobial Chemotherapy were especially high for cefozopran (63%), biapenem and meropenem (61%), and pazufloxacin (53%) and ciprofloxacin (53%). These findings suggest that prulifloxacin, pazufloxacin and biapenem, which are newly introduced, are clinically effective in the treatment of infection caused with P. aeruginosa.
    The Japanese journal of antibiotics 11/2005; 58(5):445-51.
  • Article: [Surveillance of antimicrobial resistance of Streptococcus pneumoniae isolates from the Kinki Region of Japan during 2003/2004. The Surveillance Program of Bacterial Resistance in the Kinki Region of Japan; SBRK].
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    ABSTRACT: Three hundred seventy five isolates of Streptococcus pneumoniae were collected from 14 medical institutions in the Kinki region of Japan between November 2003 and February 2004. We determined the minimum inhibitory concentration (MIC) of penicillin G (PCG) and 25 of other antimicrobial agents against these isolates according to the National Committee for Clinical Laboratory Standards (NCCLS). Overall, 71.5% of all isolates were resistant to PCG (intermediate and resistant categories were 51.7% and 19.8%, respectively). For the carbapenems and penem, the rank order of activity was PAPM (MIC90, 0.12 microg/ml) > IPM (0.25 microg/ml) > MEPM (0.5 microg/ml) = FRPM (0.5 microg/ml). For the cephems, the overall rank order of activity was CPR (MIC90, 0.5 microg/ml) = CDTR (0.5 microg/ml) > CTRX (1 microg/ml) = CTX (1 microg/ml) = CZOP (1 microg/ml) = CFPN (1 microg/ml). Rank order activity for six of fluoroquinolones was TFLX = MFLX (MIC90, 0.25 microg/ml) > GFLX (0.5 microg/ ml) = SPFX (0.5 microg/ml) > LVFX (1 microg/ml) > PZFX (4 microg/ml). The rate of resistance to fluoroquinolones per the NCCLS criteria were very low, ranging from 0.7% to 2.6%. Rate of resistance to other antimicrobiotics were CAM, 77.0%; CLDM, 41.7%; TEL, 0%; VCM, 0%; ST, 32.7%, and CP, 21.4%.
    The Japanese journal of antibiotics 07/2005; 58(3):221-30.
  • Article: [Three sisters of pulmonary Mycobacterium avium complex disease].
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    ABSTRACT: We reported three sisters of pulmonary Mycobacterium avium complex (MAC) disease. The oldest sister was complaining of bloody sputum, and cultures were positive for M. avium. By monotherapy with clarithromycin, symptom and imaging findings had shown no progression for six years. The second sister was complaining of productive cough, and cultures were positive for M. intracellulare. Her symptom and imaging findings had shown no progression for seven years without any treatment. The third sister had rheumatoid arthritis and diabetes mellitus, and cultures were positive for M. intracellulare. Although she received chemotherapy with rifampicin, clarithromycin, ethambutol, and kanamycin, symptom and imaging findings had progressed gradually. She died of respiratory failure four years later. Autopsy findings revealed no disseminated MAC disease. The results which three cases showed different isolate patterns and clinical courses suggest the importance of underlying anti-mycobacterial immunological impairment and defects of local host defense rather than virulence of infected strains as the pathogenesis of pulmonary MAC disease.
    Kansenshogaku zasshi. The Journal of the Japanese Association for Infectious Diseases 06/2005; 79(5):341-7.
  • Article: [Sepsis and blood culture management].
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    ABSTRACT: At Tenri Hospital in Nara prefecture of Japan, the blood culture system is managed by a medical technologist with a microbiology specialty, and the other medical technologists manage the blood culture system when the primary technologist who specializes in microbiology is not working in 24 hours. For positive cultures, the Gram staining morphology of the organism is reported direct by to the clinician by telephone within 24 hours after culture bottles are submitted to the laboratory. We, the medical technologist, discuss with the clinician the focus of infection, use of antibiotics, effects of antimicrobial therapy, and clinical background of the patient. In some cases, we examine the MICs of specific bacteria isolated from patients and calculate the pharmacokinetic (PK)/pharmacodynamic (PD) parameters(e.g., time above the MIC, area under the curve/MIC and peak concentration/MIC). We then recommend to the clinician the most suitable dosage regimen. For patients with a serious infection or renal failure requiring a special dosing regimen, we perform therapeutic-drug monitoring with various antimicrobial agents. Information for rapid diagnosis of bacteremia and suitable dosing regimens for antimicrobial agents should be provided to the clinician with the following considerations: (1)findings should be reported within 24 hours of receiving a specimen, (2)the report should include a therapeutic regimen that considers the MIC of the target bacteria, and (3)the MIC interpretive criteria that correspond to the dosage regimen should be adopted.
    Rinsho byori. The Japanese journal of clinical pathology 05/2005; 53(4):329-34.
  • Article: [Susceptibility of ESBL-producing Escherichia coli and Klebsiella pneumoniae to various antibacterial agents].
    Tatsuya Nakamura, Masaru Komatsu
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    ABSTRACT: With the increasing use of broad-spectrum antibacterial agents, the increase in various drug-resistant bacterial strains has become a concern in recent years. Especially, the development of drug-resistance by Enterobacteriaceae which significantly affects therapy and prognosis in sepsis and lower gastrointestinal post-operative infection. The extended spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae strains isolated in the Surveillance Program of Bacterial Resistance in Kinki region of Japan (SBRK) were supplied between November 2000 and March 2003. The susceptibilities of them to 16 kinds of antimicrobial agents were investigated. The number of them was 48 strains consisting of 36 Escherichia coli strains (75%) and 12 Klebsiella pneumoniae strains (25%). Our focus was on carbapenem and the new quinolone antibacterial agents. Among the 16 major antibacterial agents examined, carbapenem had low MIC50/90 values. Meropenem had a MIC50/90 of 0.03/0.06microg/ml, followed by biapenem (0.12/0.5), imipenem (0.25/0.5) and panipenem (0.25/0.5). Among cephem, ceftazidime had the lowest MIC50 at 4 microg/ml. All four of the cephem agents had a MIC90 of greater than 128microg/ml. Among beta-lactamase inhibitors, tazobactam/piperacillin had the lowest MIC50 at 4 microg/ml, and sulbactam/cefoperazone had a MIC50 of 32 microg/ml. Among the new quinolones, prulifloxacin had the lowest MIC50 at 1 microg/ml, and the other drugs had a MIC50 of 2 microg/ml. The resistance rate of ciprofloxacin was 61.1% in E. coli and 16.6% in K. pneumoniae. Comparison of drug-sensitivity to cephem by ESBL-gene type revealed that cefpirome, cefepime and cefozopran had higher MIC50/90 values against the CTX-M group with a MIC50 of greater than 128microg/ml. Ceftazidime and aztreonam had higher MIC50/90 values against the TEM/SHV group than those against the CTX-M group. In the CTX-M group, the MIC50 was 4 and 16microg/ml, respectively.
    The Japanese journal of antibiotics 03/2005; 58(1):1-10.
  • Article: In vitro activity of beta-lactams and quinolones against AmpC beta-lactamase-producing Escherichia coli.
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    ABSTRACT: We studied the antimicrobial susceptibility of AmpC beta-lactamase-producing Escherichia coli isolates collected at ten medical institutions in the Kinki area of Japan during a 6-month period (November 2002 through April 2003). Of 2845 E. coli isolates tested, 29 (1.0%) showed a minimum inhibitory concentration (MIC) for cefazolin of more than 8 microg/ml and were three-dimensional extract test positive. In standard inoculum susceptibility tests against these 29 strains, the MIC90s for the four carbapenems tested ranged from 0.06 microg/ml to 0.5 microg/ml, and these compounds were more active than the other beta-lactams, with meropenem being the most active. The MIC90s for beta-lactams, except carbapenems, ranged from 4 microg/ml to 32 microg/ml, with cefepime being the most active. In high inoculum susceptibility tests against these strains, the MIC90s for the four carbapenems and cefepime were 8 microg/ml or less, and these compounds were more active than other beta-lactams. The MIC90s for beta-lactams, except carbapenems and cefepime, were 32 microg/ml or more. The MIC90s for the five quinolones tested ranged from 4 microg/ml to 16 microg/ml, and the order of increasing susceptibility was ciprofloxacin > levofloxacin, gatifloxacin and pazufloxacin > prulifloxacin.
    Journal of Infection and Chemotherapy 03/2005; 11(1):9-13. · 1.80 Impact Factor
  • Article: Metallo-beta-lactamase-producing gram-negative bacilli: laboratory-based surveillance in cooperation with 13 clinical laboratories in the Kinki region of Japan.
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    ABSTRACT: A total of 19,753 strains of gram-negative rods collected during two 6-month periods (October 2000 to March 2001 and November 2001 to April 2002) from 13 clinical laboratories in the Kinki region of Japan were investigated for the production of metallo-beta-lactamases (MBLs). MBLs were detected in 96 (0.5%) of the 19,753 isolates by the broth microdilution method, the 2-mercaptopropionic acid inhibition test, and PCR and DNA sequencing analyses. MBL-positive isolates were detected in 9 of 13 laboratories, with the rate of detection ranging between 0 and 2.6% for each laboratory. Forty-four of 1,429 (3.1%) Serratia marcescens, 22 of 6,198 (0.4%) Pseudomonas aeruginosa, 21 of 1,108 (1.9%) Acinetobacter spp., 4 of 544 (0.7%) Citrobacter freundii, 3 of 127 (2.4%) Providencia rettgeri, 1 of 434 (0.2%) Morganella morganii, and 1 of 1,483 (0.1%) Enterobacter cloacae isolates were positive for MBLs. Of these 96 MBL-positive strains, 87 (90.6%), 7 (7.3%), and 2 (2.1%) isolates carried the genes for IMP-1-group MBLs, IMP-2-group MBLs, and VIM-2-group MBLs, respectively. The class 1 integrase gene, intI1, was detected in all MBL-positive strains, and the aac (6')-Ib gene was detected in 37 (38.5%) isolates. Strains with identical PCR fingerprint profiles in a random amplified polymorphic DNA pattern analysis were isolated successively from five separate hospitals, suggesting the nosocomial spread of the organism in each hospital. In conclusion, many species of MBL-positive gram-negative rods are distributed widely in different hospitals in the Kinki region of Japan. The present findings should be considered during the development of policies and strategies to prevent the emergence and further spread of MBL-producing bacteria.
    Journal of Clinical Microbiology 12/2004; 42(11):5256-63. · 4.15 Impact Factor
  • Article: [Application of the MIC breakpoints based on pharmacokinetics and pharmacodynamics parameter in the clinical laboratory].
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    ABSTRACT: The effectiveness of time-dependent antibiotics such as beta-lactams is related to the time above the MIC (TAM, %). We constructed a program to calculate the TAMs of beta-lactams using the pharmacokinetic parameters of the Japanese dosing regimen of a phase I study of the Japanese Society for Antimicrobial Chemotherapy (JSAC), and compared them with the MIC breakpoints published by the National Committee for Clinical Laboratory Standards (NCCLS) and JSAC. If the effective TAM was assumed to be more than 40% of the dosing interval, the pharmacokinetic/pharmacodynamic (PK/PD) breakpoints calculated by our program were in agreement with the JSAC breakpoints for pneumonia within 1 dilution MIC. When comparing with the NCCLS breakpoints for Enterobacteriaceae or Staphylococcus, the PK/PD breakpoints dosing three times per day of ampicillin (1 g, intravenous dose; i.v.), piperacillin (2 g, i.v.), cefotaxime (1 g, i.v.) and cefmetazole (1 g, i.v.) were calculated to be less than 2-fold dilution MIC, and those of amoxicillin (0.25 g, oral dose; p.o.) and cefaclor (0.5 g, p.o.) were calculated to be less than 3- to 4-fold dilution of MIC. Our program could calculate TAMs and PK/PD breakpoints by inputting the two factors of MIC and dosing interval. If this information is routinely reported to physicians from clinical laboratories, an appropriate dosing schedule could be proposed for various infectious cases.
    The Japanese journal of antibiotics 01/2004; 56(6):697-704.