Upper gastrointestinal endoscopes are essential for the optical diagnosis of gastric cancer and duodenal ulcer, as well as for the evaluation of treatment response. The tip of the gastrointestinal endoscope is approximately 10 mm in diameter, and has a narrow accessory channel (2.8 mm diameter) to allow the insertion of various types of accessory. To prevent cross infection, gastrointestinal endoscopes must be cleaned and disinfected properly. To evaluate the cleanliness and contamination, microorganism and protein detection methods have been adopted. However, special reagents and equipments are required to detect the protein. Moreover, microorganism detection takes about 24 hours to culture microorganisms. Consequently, evaluation of the cleanliness and contamination of gastrointestinal endoscopes has been difficult. A bioluminescence ATP+AMP high sensitive assay kit is commercially available, and the kit is used as a cleanliness monitoring and control tool. This procedure consists of using a wipe to sample the surface of the objects, which is then placed in a small equipment and mixed with reagent. The method measures the amount of luminescence obtained. We evaluated contamination and cleanliness of upper gastrointestinal endoscope channels before and after cleaning with long stem swabs (40 cm in length with 2.8 mm diameter cotton bud). In addition, we selected one of the 15 upper gastrointestinal endoscopes and evaluated the contamination and cleanliness by measuring ATP+AMP every day for 11 months. We have defined the institutional criteria for the allowable value of ATP+AMP after manual cleaning as 100 RLU. In addition, detection of a value over 100 RLU requires that the upper gastrointestinal endoscope must be cleaned and disinfected again.
Measles has been successfully eliminated as a widespread disease in Japan, so healthcare workers, laboratory personnel and epidemiological investigators should take special care to avoid becoming infectious carriers. We conducted a questionnaire investigation on measles immunization status and infection history among all staff working for our institute, and measles antibody levels were measured by the gelatin particle agglutination (PA) test with informed consent. Among all 44 staff except 3 individuals on leave, 42 staff underwent the test, of whom 36 showed positive measles antibody with preventive level of infection (256 times or more). Among 4 staff with immunization records of 2 doses, 3 staff showed positive measles antibody with adequate levels for a health care worker. Another staff member had negative (under 16 times) measles antibody level, so received the measles-rubella vaccine after recommendation. Totals of 15 of 17 staff with immunization record of 1 dose and 18 of 21 staff with no immunization record also showed adequate positive measles antibody level. Among the 5 staff with inadequate positive measles antibody level (16, 32, 64, 128 times) for a health care worker, 2 had immunization record of 1 dose and one staff a record of infection. All staff members were conscious of their official responsibility and most measles antibody levels were adequate for a health care worker. However, some staff showed negative or inadequate measles antibody level in spite of immunization record. Assessment of the immunization background and measurement of the measles antibody level will support efficient vaccine recommendation for measles prevention in local institutes of public health.
We established a surveillance system for vascular-access associated infections (VAIs) in 2008. This study evaluated the epidemiology of VAIs in our surveillance system to identify risk factors of VAIs using data submitted from 29 participating hospitals between 2008 and 2013. A total of 350 VAIs were observed of which 75, 33, 12, 205 and 25 were associated with arteriovenous (AV) shunt, AV graft, superficialization of the brachial artery, non-cuffed catheter and cuffed catheter, respectively. Incidences of VAIs per 1,000 dialysis sessions were 0.08, 0.76, 0.26, 12.16 and 1.15, respectively, and comparable to those reported in the United States. Patients with catheters were more likely to develop bloodstream infections, and the majority of pathogens were Stapylococcus aureus including methicillin-resistant strains. Non-cuffed catheter was the major risk factor for VAIs. Other risk factors identified in patients with catheters included diabetes and catheter indwelling at the femoral site. We observed a decreasing trend of VAI incidence over time, which we think was the result of quality improvement in each hospital. Future directions include implementation of infection prevention strategy based on these results, as well as investigation of additional risk factors.
Reliability of a commercially available chemical product sold in Japan that claims to inactivate viruses by releasing chlorine dioxide gas was investigated. The viral fluid of influenza A/Aichi/2/68 strain virus propagated in the allantoic fluid of fertilized chicken eggs was atomized by a nebulizer in a 1.8 cubic meter-space closed environment, with the temperature and relative humidity set at about 23℃ and 30%, respectively, which resemble room conditions during the winter season. The concentration of the gas was manually adjusted at about 0.03–0.04 ppm by opening and closing the bottle cap. After a specified time, 80 L of air was sampled and filtered through a gelatin filter to trap the aerosol which contained the virus, and the amount of the active virus was titrated by plaque assay. The amount of active viruses was similar in both the gas-exposed air and the control air, indicating that the gas had no inactivating properties under these conditions. Validating the bactericidal and virucidal abilities under various conditions is essential before applying such a material to actual infection control.
Sodium hypochlorite is used as hospital disinfectant, but quality assurance is not usually performed. We measured the chlorine concentration in diluted hypochlorite solutions made from the original solutions (including 6% sodium hypochlorite) by a simple colorimetric method and compared the findings with the calculated concentration. Twenty samples from 19 wards were used and the factors affecting the concentrations were examined. The samples ranged in chlorine concentration from zero to 800 ppm, and 17 measurements were lower than the calculated values. Two samples were diluted by the incorrect methods, and the original solution used in one ward had chlorine concentration lower than 6%. The chlorine concentration may be affected by the incorrect method for dilution and incorrect storage conditions. Therefore, we recommend standard methods to store and dilute the hypochlorite solutions throughout the hospital. The colorimetric method is simple and inexpensive to measure chlorine concentration, and can be easily applied to disinfectant validation and stewardship.
Healthcare Associated Infection (HAI) by tuberculosis is still a serious problem in Japan. In our hospital, 3 patients were newly diagnosed with pulmonary tuberculosis after admission in 2009, and many resources were needed for the surveillance of exposed individuals. For the early detection of tuberculosis, we have continued routine Acid-Fast Bacillus (AFB) smear examinations in elderly (older than 60 years old) inpatients when sputum cultures are ordered since September 2010. A total of 2646 additional routine AFB smears were examined without orders from the physicians in charge from September 2010 to December 2014. Five specimens (0.19%) were revealed as AFB positive. After intervention, the total number of exposed individuals for the surveillance of tuberculosis were reduced by 56, from 152 to 96, but the numbers of such individuals per patient with tuberculosis were not significantly different. The saving in cost for the survey per individual was about 868 yen, rather lower than the cost of surveillance per individual of about 2933 yen. Early detection is vital to prevent HAI by tuberculosis based on screening examinations. This study shows that routine AFB testing both on admission and during hospital stay may be useful for the early detection of tuberculosis and saving of costs for contact surveys. In addition, we suggest that maintenance of the support system of diagnosis and education about tuberculosis for physicians should be included in future infection measures.
The present study used antimicrobial consumption surveillance to assess the resistance rate transition of Pseudomonas aeruginosa in facilities cooperating in infection prevention medical fees using the antimicrobial use density (AUD) and days of therapy (DOT) as parameters, and compared the surveillance results in 2014 to 2012. In our hospital, the change in DOT of first-generation cephalosporins, third-generation cephalosporins, fourth-generation cephalosporins, carbapenems, aminoglycosides, glycopeptides was greater than that of AUD. In stroke center, the change in DOT of penicillins, antipseudomonal penicillins, carbapenems was greater than that of AUD. The surveillance comparing the AUD transition with DOT transition revealed the influence of antimicrobial dose and duration on the change of AUD was more accurately evaluated by surveillance using the AUD transition with DOT transition. In both facilities, the antimicrobial dose and duration were not associated with change in the resistance rate of P. aeruginosa. The present results suggest that the effects of change in antimicrobial dose and duration transition on the change in resistance rate of P. aeruginosa are limited.