Biomedical subjects

Yukako Shimojima

Publications and source records attributed to Yukako Shimojima.

6 recordsLinked to original sources

PubMed2006

[Isolation of thermostable direct hemolysin producing Vibrio parahaemolyticus from food using screening by PCR in food-borne outbreaks].

The producibility of thermostable direct hemolysin (TDH) is the most important pathogenic factor in Vibrio parahaemolyticus. TDH (+) V. parahaemolyticus is usually isolated from patients having V. parahaemolyticus food-borne disease. TDH (+) V. parahaemolyticus is, however, very difficult to isolate from food and environmental samples. In the 5 years from 2000 to 2004 in Tokyo, V. parahaemolyticus was isolated from food samples related to 67 of 227 V parahaemolyticus food-borne outbreaks. In these outbreaks, TDH (+) strains were also tried to isolate using PCR as the screening methods. TDH (+) V. parahaemolyticus strains were able to isolate from enrichment broth in which toxR and tdh genes become positive in PCR. TDH (+) strains of the same serotype with patients were able to be isolated from 23 food samples related to 11 outbreaks (16.4%); 3 outbreaks in 2000, 2 in 2001, 2 in 2002, 1 in 2003, and 3 in 2004. The serotypes of V. parahaemolyticus isolated from food were O3 : K6 (10 samples), O3 : K5 (6 samples), O1 : K25 (4 samples), O3 : K29 (2 samples), O4 : K 8 (1 sample), and O4 : K11 (1 sample). The isolation rate of the TDH (+) strain from enrichment broth differed with samples. In several samples TDH (+) strains were isolated easily only by examining 3 colonies, hence no TDH (+) strains were isolated in spite of the examination of 250 colonies. No correlation was seen between the number of V. parahaemolyticus and the isolation rate of TDH (+) strains in food samples. Screening using PCR is very effective method for isolating TDH (+) V. parahaemolyticus from food samples.

Disease Outbreaks↗

PubMed2006

Novel method for estimating viable Salmonella cell counts using real-time PCR.

A novel method for estimating viable Salmonella Enteritidis cell counts with 5'-nuclease real-time PCR was developed in this study. Our method was based on the increase kinetics of the target DNA region (invA) of the microorganism growing in a food/clinical sample in a culture medium during incubation. The index of increase in the target DNA region studied here was threshold cycle, CT. A test Salmonella strain was grown in buffered peptone water at the optimal temperature (39 degrees C). As Salmonella cells were grown, the value of CT decreased with time, generating a downward sigmoidal curve. The slope of the curve was constant at various initial cell concentrations. With higher initial cell concentration, the CT value evaluated from the slope at a given time was lower. With this relationship, a novel method for estimating the initial viable cell concentration of a sample was developed. Dead Salmonella cells or bacteria other than the target cell caused deviation in the CT curve. Incubation in a selective media suppressed the deviation caused by other bacterial cells. We think that this method could be applied to many other microorganisms cultivable in a suitable medium.

Colony Count, Microbial↗

PubMed2005

[Drug susceptibility and analysis using pulsed-field gel electrophoresis of Streptococcus pyogenes strains isolated from the patients with streptococcal toxic shock syndrome (STSS) in Japan].

Previously, we have performed T typing of Streptococcus pyogenes strains isolated from patients with streptococcal toxic shock syndrome (STSS) in Japan, and streptococcal pyrogenic exotoxin (SPE) typing for epidemiological examination. In this study, we conducted a drug sensitivity test using these strains, and investigated the results of gene analysis by pulse-field gel electrophoresis (PFGE) of S. pyogenes strains derived from patients with STSS, the patient's family, and patients other than those with STSS. To clarify the relationship between the host and bacterial factors, we investigated the association between clinical symptoms and T typing of the isolated strains/production of streptococcal pyrogenic exotoxin. There were no strains resistant to beta-lactams, and only 1 strain was resistant to multiple agents other than beta-lactams. The PFGE pattern of T1 type strains was classified into 2 ; the pattern was consistent between the strains derived from patients with STSS and those derived from the patient's family. The PFGE pattern of T3 type strains was classified into 5 (IV) ; Pattern I, which was most frequently observed, was detected in both the strains derived from patients with STSS/non-STSS. However, Patterns II and III were detected only in the strains derived from patients with non-STSS. Patterns IV and V were detected only in the strains derived from patients with STSS. When examining the association between clinical symptoms and bacterial factors, disseminated intravascular coagulation (DIC) was associated with T1-SPE B-producing strains, and pharyngitis was associated with T3-SPE A-producing strains. In the future, the relationship between the host and bacterial factors should be further investigated.

Anti-Bacterial Agents↗

PubMed2004

[Epidemiological study on Streptococcus pyogenes strains isolated from the patients with streptococcal toxic shock syndrome (STSS) in Japan in 1992-2001].

To investigate clinical and microbiological features of streptococcal toxic shock syndrome (STSS), clinical, epidemiological, and bacteriological data obtained from 250 patients between 1992 and 2001 were analyzed. Among these 250 cases, 16 cases were excluded from the study because the causative microorganism were not Streptococcus pyogenes. 234 strains of S. pyogenes obtained from the aforementioned 234 cases were tested for T-type by a serological method, and for streptococcal pyrogenic exotoxin (SPE) by in vitro productivity of the toxin as well as molecular genetic methods. The number of patients was 141 (56.4%) for males, and 107 (42.8%) for females. The highest frequency of STSS was observed in those patients in their sixties in both sexes. The overall mortality rate was 43.2%. The mortality rate for male was 36.9%, and 52.3% for female. Bacteriological studies revealed that most common T types were T1 and T3. These strains consisted 54.3% of the strains collected. Among strains of T1 type, 98.8% possessed genes of spe A, and 46.1% were shown to produce SPE A in vitro. Among strains of T3 type, 82.9% possessed spe A gene, and all of these strains were shown to produce the toxin in vitro. It is concluded that certain strains of S. pyogenes, such as those with T1, or T3 type, and those with spe A gene or in vitro production of SPE A, are the most frequent cause of STSS. Although infections caused by such bacteria are quite common, STSS rarely occurs in most such patients. Additional factors, such as host factors, may play a crucial role in the pathogenesis of STSS.

Adolescent↗

PubMed2004

[Two nosocomial outbreaks of sepsis caused by Serratia marcescens, which occurred in July 1999 and January 2002--Tokyo].

Two nosocomial outbreaks of sepsis caused by Serratia marcescens, which occurred in Tokyo were the following cases. CASE A: In July 1999, 10 inpatients admitted to the third floor ward of the General Hospital A, developed sudden onset of high fever, coagulation disorders (disseminated intravascular coagulation), and acute renal failure, of which 5 died. Twenty-one strains of Serratia marcescens were isolated from the inpatient's blood and urine, nurse fingers and environmental samples from floor and cooling tower. Serratia infection was strongly suspected as the cause of sepsis. These cases were defined as "inpatients who developed fever 38 degrees C or more during July 26 to 29 and from whom S. marcescens was isolated by blood culture". Ten isolates were detected from the blood. In order to investigate the background of S. marcescens isolation in the hospital and to compare molecular and biochemical characteristics of S. marcescens, cultures were attempted from samples of other inpatients and staffs and hospital environment. Those were classified into 9 groups by various different typings: biotyping with Api Rapid 20; susceptibility typing of antimicrobial agents tested; pulsed-field gel electrophoresis (PFGE) typing of SpeI- or Xba I-restricted chromosome. All 10 isolates causing sepsis were found to be in the same group. CASE B: In January 2002, 24 inpatients, admitted to Neurosurgical Hospital B, developed sudden onset of high fever, of which 7 died. S. marcescens was isolated from a towel, environmental samples and inpatients. These cases were defined as "inpatients who developed fever of 38.5 degrees C and S. marcescens isolated by blood culture". Twelve strains were isolated from the blood samples in 12 cases. In order to investigate the background of S. marcescens isolation in the hospital, cultures were attempted from other inpatient's urine and environmental samples from medical tape, Tshake and a towel. These isolates were classified into 3 groups by the previous typings; biotyping with Api Rapid 20; susceptibility typing of antimicrobial agents tested; and PFGE typing. All 12 isolates in 12 cases were found to be in the same group. These cases of 2 nosocomial outbreaks of sepsis were defined as "in-patient who developed high fever and S. marcescens isolated by blood culture". However in both cases transmission routes of Serratia infection remain unknown by field investigation.

Adult↗

PubMed2003

[Usefulness of arbitrarily primed polymerase chain reaction (AP-PCR) method for DNA fingerprinting analysis of Mycobacterium tuberculosis (MTB); comparison between DNA restriction fragment-length polymorphism (RFLP) method and AP-PCR method].

We have been analyzing cases suspected as outbreak of Mycobacterium tuberculosis in Tokyo using RFLP method. This time we analyzed 27 strains of MTB from 5 cases in two hospitals, a family, member of social activity and stuff of a corporation using both RFLP and AP-PCR methods. At 4 cases, over 80% of strains were same pattern in each cases with RFLP and AP-PCR and were identified as a patient to patients transmission of MTB. At one case, in a hospital, each strains were completely different patterns at both methods, which showed it was not a outbreak case. Results of RFLP and AP-PCR were completely same, which indicates AP-PCR is also useful and rapid method for epidemiological analysis of MTB infection as well as RFLP.

Contact Tracing↗