To evaluate the activity of tuberculosis, 34 consecutive samples were examined using interferon-γ release assays (IGRA) and Mycobacterium culture examination. The results of culture IGRA was +/+ in 14 patients, +/ intermediate in 5 patients, +/− in 2 patients (both receiving anticancer treatment), −/+ in 3 patients (M. avium, MAC, and M. intracellulare were identified), −/− in 8 patients, intermediate in one patient, and indeterminate in one patient. Since many samples were indeterminate, the following experiments were performed. The value M showed the same results after the concentration of monocytes, decreased with longer incubation after challenging, and decreased after challenging with a double amount of antigen. The activity of tuberculosis should be determined comprehensively by the optical absorbance of ESAT-6, CFP-10, negative control, and positive control. IGRA is recommended as a adjunctive method.

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  The biofilm-forming capabilities and antimicrobial resistance of metallo-β-lactamase-producing Pseudomonas aeruginosa isolates were investigated and a molecular epidemiology study conducted using pulsed-field gel electrophoresis (PFGE). A total of 123 metallo-β-lactamase-producing P. aeruginosa isolates, including 79 isolates from urine, 10 isolates from sputum, 10 isolates from feces, 5 isolates from pus, 2 isolates from blood and 17 isolates from other sites, were collected from patients (one isolate per patient) admitted to three hospitals from 2001 through 2006. Of the 123 isolates, 106 (86.2%) isolates were resistant to imipenem, ciprofloxacin and amikacin, indicating multiple-drug-resistant P. aeruginosa (MDRP). The in vitro microtiter plate assay was used to quantify biofilm formation into three groups: strong (OD₅₇₀≧1) in 29 (23.6%), medium (OD₅₇₀≧0.5 to <1) in 47 (38.2%), and weak (OD₅₇₀≧0 to <0.5) in 47 (38.2%). The biofilm-forming capabilities of metallo-β-lactamase-producing P. aeruginosa isolates (mean±SE 0.71±0.04 [n=123]) were significantly greater than those of non-producing isolates (mean±SE 0.28±0.04 [n=122]). Of the 76 isolates with strong and medium biofilm formation, 71 (93.4%) isolates were MDRP and 57 isolates (75.0%) were urine isolates. PFGE analysis showed that no identical isolates were found among the 123 metallo-β-lactamase-producing P. aeruginosa isolates, but 12 paired isolates were found at a similarity level of 85%. Of the 12 pairs, one pair was found on the same day, and other pairs were found within 4-day to 3-month intervals. The persistent biofilms formed by metallo-β-lactamase-producing P. aeruginosa isolates could cause serious problems in hospital acquired infections. The development of strategies to prevent the spread of this organism in the hospital setting is needed.

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  Various antibacterial medical textiles are used in hospitals for the prevention of nosocomial infection, but antibacterial medical textiles with improved antibacterial effects and safety are desirable. We have developed fabrics made of carboxymethylcellulose-cethylpyridinium/zinc (CMC-CP/Zn). CMC-CP/Zn incorporates inorganic zinc and cethylpyridinium chloride used as a mouth wash into carboxymethylcellulose. Antibacterial effects of the CMC-CP/Zn fabric were compared with CMC-CP and CMC-Zn fabrics against the standard strains of Staphylococcus aureus ATCC25923, Staphylococcus epidermidis ATCC12228, Enterococcus faecalis ATCC33186, Escherichia coli ATCC25922, Serratia marcescens ATCC8100, and Pseudomonas aeruginosa ATCC33348. The antibacterial effects of CMC-CP/Zn fabric against the standard strains of S. aureus, S. epidermidis, and E. faecalis showed that the number of inoculated bacteria decreased to less than 1.3 log (cfu/fabric) of viable bacteria after exposure for 1 min, and the excellent antibacterial effects were comparable to CMC-CP fabric. The antibacterial effects of CMC-CP/Zn fabric in short exposure times against E. coli, S. marcescens, and P. aeruginosa were lower than those observed against the gram-positive bacteria, but the number of inoculated bacteria decreased to less than 1.3 log (cfu/fabric) of viable bacteria after exposure for 10-30 min. The antibacterial effects of CMC-CP/Zn fabric against clinical isolates of gram-positive and negative bacteria, 7 types of bacteria and 53 strains (including drug-resistant strains) were equal to those against the standard strains.

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  The effects of four types of safety-engineered devices (SEDs) on needlestick injury (NI) rates were evaluated during a six-year period (2002-2007) at a 520-bed teaching hospital. The devices were winged steel needles (WSNs), IV catheters (IVCs), lancets (LANs), and implantable port access needles (IPNs). A total of 471 NIs were reported, of which more than 60% were caused by hollow bore needles. Device-specific NI rates were significantly lower for SEDs than non-SEDs in the use of WSNs (11.0 vs 25.1 per 100,000 devices delivered, p<0.01) and IVCs (1.0 vs 6.6 per 100,000 devices delivered, p<0.01). Use of SEDs was also associated with significantly lower risks of NIs in the use of WSN (RR=0.44, 95%CI=0.31±0.61) and IVC (RR=0.16, 95%CI=0.05±0.50). There were strong (r=−0.94, p<0.01) and moderate (r=−0.53, p=0.15) negative correlations between yearly SED use rates and NI rates in the use of WSNs and IVCs, respectively. Safety-engineered LANs and IPNs had been used for less than 1 year, and although NI rates for SEDs were lower than non-SEDs (LAN=0.0 vs 0.8 per 100,000 devices delivered, p=0.42; IPN=0.0 vs 41.2 per 100,000 devices delivered, p=0.19), the differences were not significant. In addition to introducing SEDs, promoting their use to replace non-SEDs is effective in reducing NI rates.

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  To compare surgical site infection (SSI), the risk-adjusted index is the standardized infection ratio (SIR). A statistical test for SIR is proposed using software provided by the Centers for Disease Control and Prevention (CDC). Comparison of observed SSI number (SSI_O) and expected SSI number (SSI_E) uses the Risk Index Category for adjustment. In the formula SIR=SSI_O/SSI_E, SSI_E is obtained as the total sum of SSI probabilities for the respective category stratification. The test ratio approximates to the normal distribution by z-transformation. If SSI_E≧5, the z-test is indicated. If SSI_E<5, either the binomial test or the Poisson test is recommended using, for example, Epi Info^TM 6 provided by CDC. Multiple tests repeated for the category stratifications may lead to the Type I error, which the test on SIR would offset.

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  The causes of a pseudo-outbreak of Mycobacterium chelonae were investigated at a hospital. A total of 20 M. chelonae isolates obtained from the sputa of out patients between 1 December, 2007 and 31 January, 2008 and two isolates from environmental sources were analyzed by pulsed-field gel electrophoresis (PFGE) and enterobacterial repetitive intergenic consensus PCR (ERIC-PCR) to identify the outbreak strain. M. chelonae strains from 20 patients and drinking water from the water reservoir were indistinguishable according to the PFGE and ERIC-PCR patterns. Therefore, the pseudo-outbreak of M. chelonae was associated with the water reservoir system.

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  Strains of vancomycin resistant Enterococcus (VRE) were detected in a patient with acute pancreatitis and a patient with pancreatic cancer in May and June 2006. Analysis of VRE isolates by pulsed-field gel electrophoresis detected the same gene pattern, suggesting spread within a ward. To prevent further spread of VRE, the infection control team including link nurses and ward staff provided re-education of precautions against infection to staff, full-time attending nurses, and the provision of a standstill-type trash box for infection waste. As a result, further incidents of VRE infection have not occurred. The present cases suggest that VRE infection can be treated with antimicrobial agents excluding vancomycin.

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  Infection control team (ICT) activity was established by introduction of a therapeutic drug monitoring (TDM) system and a use evaluation system to promote the appropriate use of anti-methicillin resistant Staphylococcus aureus (MRSA) drugs. As a result, the frequency of TDM for anti-MRSA drugs was significantly increased, to 55.7% in 2007. The total amount of anti-MRSA drugs used decreased with time, with a decrease of 29.8% in 2007 from 2005. In addition, the decrease in vancomycin use was large, with significant decrease of 53.2% in 2007 from 2005. These findings suggest that ICT action for the appropriate use of anti-MRSA drugs resulted in high frequency of TDM for anti-MRSA drugs, and effective decrease of anti-MRSA drug use in our hospital.

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  The effect of portable hand rub-gel was examined among nurses. The portable hand rub-gel introduction group and the non-introduction group were set up. The investigation used the crossing method changed after four complete weeks. Change of the amount used was entered into the index. Moreover, the effect of any difference in the amount of hand rub-gel used was estimated from investigation of the action pattern to perform skin disinfection. Furthermore, the amount of rub-gel used and the relationship of hand irritation was considered. As a result, the direction of introducing portable hand rub-gel increased the amount of rub-gel used. Enlightement of rub-gel use were identified. However, the results do not precisely indicate at what time skin disinfection is required. Possibly no unified model of skin disinfection can be proposed. For hand roughness evaluation, the skin replica method, the skin tape stripping method, and the questionnaire survey were carried out. There was no correlation between the number of times of skin disinfection, and dry hand area. The increase in the gel amount used did not correlate with hand irritation increase.

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  A patient with suspected Creutzfeldt-Jakob disease (CJD) was admitted to undergo surgery for a femoral neck fracture. This procedure encountered several important issues relating to infection prevention. Our decision to admit the patient for surgery was largely influenced by an agreement signed with a medical device manufacturer about the decontamination process for borrowed surgical devices. Prior to surgery, a manual including information on sterilization and disinfection in CJD surgery was prepared at very short notice to deal with selection of the minimal amount of required steel devices used over a 2-day period, handling of such equipment following surgery, and environmental factors in the operating room. According to the 2002 Ministry of Health, Labor and Welfare Manual, the optimal handling of devices used in CJD patients requires cleaning using chemical solutions such as dodecyl sodium sulfate or formic acid, but small hospitals do not have facilities for sterilization using such special chemicals. Taking into account metal corrosion, we decided to incinerate the devices purchased for surgery. Also, borrowed devices were returned after soaking in sodium hypochlorite solution for 120 min and sterilization in an autoclave (132°C, 1 h). High costs were incurred because device handling took 5 times longer than usual, large quantities of disinfectants were used, and some devices required disposal. The 2008 prion disease prevention guidelines indicate handling methods for surgical devices used for procedures with a higher risk of CJD infection to reduce the risk for secondary CJD infection. In the field of orthopedics, certain procedures associated with spinal surgery are considered high risk, and we plan to further investigate surgery on CJD patients.

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