An in vitro model of periodontopathic bacteria biofilm was established and the killing activity of various gargles including povidone-iodine gargle (PVP-I) determined with this model. Actinobacillus actinomycetemcomitan Y4 (ATCC 43718) biofilm was formed by culturing this strain on polycarbonate membrane (PCM). Similarly, mixed biofilms of A. actinomycetemcomitans Y4, Streptococcus oralis ATCC 10557, and Fusobacterium nucleatum ATCC 25586 were formed (co-aggregation) by culturing a mixture of these strains on PCM. Exposure of the A. actinomycetemcomitans biofilm formed by culturing for one day or three days to 0.23% PVP-I for 3 min reduced the count of viable cells by-3.59 and -3.39 (Δlog₁₀CFU/mL), respectively. The killing activity of PVP-I was stronger than those of 0.02% benzethonium chloride (BEC) and 0.002% chlorhexidine gluconate (CHG). Repeated exposure of this biofilm to 0.23% PVP-I (for 1 min, 3 times a day for 5 consecutive days) reduced the count of viable cells on the 5th day by -4.85 in the biofilm formed by one day culture and -3.55 in the biofilm formed by three day culture (Δlog₁₀CFU/mL).
Exposure of the mixed biofilm containing A. actinomycetemcomitans, S. oralis and F. nucleatum cultured for one day to 0.23% PVP-I for 3 min reduced the count of viable cells by <-3.00, -2.31, and <-1.50 (Δlog₁₀CFU/mL), respectively. The killing activity of PVP-I against the mixed biofilm was stronger than those of 0.02% BEC and 0.002% CHG. PVP-I is very effective against periodontopathic bacteria biofilms.

View full abstract

Pseudomonas aeruginosa strains that produce metallo-beta-lactamases (MBLs) have been detected in many hospitals in Japan, and are becoming a common cause of nosocomial infections. Since early 2002, our hospital has experienced hospital-acquired infections due to multidrug-resistant, MBL-producing P. aeruginosa strains. We surmised that such strains have been induced by the overuse and long-term administration of carbapenems, together with insufficient infection-control measures in the hospital. Our Infection Control Team instituted, as of January 2003, strict guidelines for ensuring the correct use of antimicrobial agents, including restrictions on the indications and duration of administration of carbapenems. At the same time, strict standard prevention procedures and measures to prevent contact infections were begun. The antimicrobial use density (AUD) value for carbapenems decreased significantly (p<0.01) from 22.6±3.9 before implementation of the guidelines (Jan. 2002-Dec. 2002) to 9.3 1.3 (Jan. 2003-Dec. 2003) and 5.5±0.9 (Jan. 2004-Dec. 2004) after implementation. Moreover, the incidence of P. aeruginosa isolates resistant to imipenem (IPM) decreased significantly (p<0.01) from 20.5% before implementation to 13.8% and then 5.7% after implementation, and the incidence of detection of multidrug-resistant P. aeruginosa decreased significantly (p<0.01) from 5.1% to 1.7% and then 0.7%. Thus, decreased use of carbapenems and restriction of duration of administration successfully reduced the manifestation of IPM-and multidrug-resistant P. aeruginosa. These results show the possibility of achieving control over nosocomial infections due to multidrug-resistant P. aeruginosa by rigorously implementing institutional guidelines, including correct use of antimicrobials. There is an urgent need for preparation of standard guidelines detailing countermeasures for multidrug-resistant P. aeruginosa, including correct management of the use of antimicrobials.

View full abstract

A nosocomial outbreak of vancomycin-resistant enterococcus (VRE) has occurred in a Yamanashi prefectural hospital in Japan. We investigated the outbreak to determine the risk factors for VRE infection and identify the routes of infection. A case was defined as a patient hospitalized from 1 January to 23 June 2004 with positive findings for VanB type VRE in any stool specimen. Stool specimens were collected from all inpatients and staff for VRE isolation. The strains of VRE were analyzed by pulsed-field gel electrophoresis (PFGE). Clinical and epidemiological information was collected by reviewing hospital records, staff interviews, and inspections. Twenty four cases (10 males, 14 female) were identified. All patients were asymptomatic. All strains isolated from the cases were identical with the PFGE pattern. The procedures for washing hands, changing diapers and cleaning the environment in the ward were inadequate to prevent transmission. A patient who touched the floors with his hands was strongly suspected to have acquired VRE from the floor contaminated with another VRE patient's stool. A case-control study was conducted among patients who were in the hospital from 1 April to 23 June 2004 to determine risk factors. The study revealed associations between antibiotic use within the past month and VRE infection (OR 8.91, 95% CI 1.1-72.8). We concluded that VRE was transmitted from infected patients to other patients through the hospital staff hands or clothing and the environment, including the floors. We recommended that the hospital separate the infected patients from the uninfected patients and improve procedures for washing hands, changing diapers and cleaning the ward, including the floors, if patients touch them directly. The hospital accepted these recommendations and the outbreak ended.

View full abstract

Cases of invasive aspergillosis are reported to increase during construction work in a hospital. Our hospital underwent reconstruction beginning in December 2002, so we investigated good surveillance methods for the prevention of invasive aspergillosis. The first trial surveyed the positive rate in the serum aspergillus antigen test among samples. Positive rate had been less than 4% from the first half of 1999 to the first half of 2002, but increased to 7.6% in the second half of 2002 and 14.3% in the first half of 2003. However, the positive rate among immunocompromised patients apparently did not increase. The sensitivity of test increased in September 2002, as the method was changed from agglutinin assay to ELISA. Therefore, the change of assay was thought to be the reason for the increase. The second trial excluded multiple samples from the same patient to investigate the positive rate among patients. The positive rate increased to 6.3% in early half of 2005 from 3.5% in the first half of 2004 and 3.2% in the second half of 2004. We found the number of positive patients increased in the wards, in particular in the division of hematology. The increase in positive patients coincided with the transfer of clean rooms to a new ward. Therefore, we suspected this operation to be the cause. Fortunately, no patients with invasive aspergillosis were found, but positive findings were limited to terminal malignancy patients in the wards. Thereafter, we established guidelines and a new manual for prevention of invasive aspergillosis. Surveillance based on the serum antigen test is one of the best methods for prevention.

View full abstract

The preparation of injection mixtures, mainly for intravenous hyperalimentation (IVH), is increasing in medical institutions. The importance of infection control in preparation of injection mixtures under sterile conditions, such as in a clean bench for IVH and a safety cabinet for anticancer drugs, has been emphasized. We conducted a questionnaire survey on the status of the preparation of injection mixtures in medical institutions. The questionnaire included whether the institution has clean benches and/or safety cabinets, which medical staff prepare injection mixtures, clothing during injection mixture preparation, and whether and what kind of filters are used for the preparation of injection mixtures and administration of IVH. Answers were obtained from 118 institutions.
Clean benches were installed in 94.1%, and safety cabinets in 71.2%, of the institutions. Most of them were installed in the pharmaceutical department. However, the preparation of IVH, anticancer, and other injection mixtures was often performed in under-equipped conditions by nurses. More than 70% of the pharmacists wore dust-free garments, gloves, masks, and caps, but far fewer of the other medical staff members wore such garments. The rate of the application of inline filters to IVH was 79.7%, and the rate of the application of membrane filters to injection mixture preparation was 49.4%.
Infection control requires the promotion of the utilization of equipments installed in pharmaceutical departments and preparation of injection mixtures by pharmacists.

View full abstract

The details of needlestick and sharp instrument injuries were collected from April 1996 to November 2004 using the report format of EPINet (Japanese Version), and software developed by our hospital. The recorded data were correlated to investigate the percentage and the number of cases, classified by monthly occurrence, occupation, year, place, cause, and equipment. The relationships between the risk of needlestick and sharp instrument injuries with these factors were assessed. The annual number of occurrences decreased year by year. In particular, pincushion injuries from a needle with a disposable injector decreased, resulting from the introduction of the equipment for blood-gas analysis with a safety device. The sickroom was the most common location of needlestick and sharp instrument injuries. The needle of the disposable injector was the most dangerous type of equipment, followed by winged steel needles.“At recapping” was the procedure most involved in needlestick and sharp instrument injuries, followed by “Until It Discards”. However, the annual changes showed that the percentage of “At recapping” decreased, and the percentage of “Until it Discards” increased. After the establishment of the prohibition of recapping, the used needle could not be disposed of immediately in the sickroom where the needle is used frequently, because there were no drop-off containers nearby. In the future, steps should be taken to handle the used needles. The statistics of needlestick and sharp instrument injuries prove that the long-term accident prevention measures taken are effective, but also showed that the HBs antibody level of the injured medical staff tended to be low, so preventive measures should be established urgently.

View full abstract

The use of cephems had grown at our hospital to account for nearly half of all antimicrobial agents prescribed. Quotas for cephems were set and assigned to each ward, and staff information sheets were distributed to all sections after discussion at the committee for prevention of nosocomial infection. As a result, both total use of antimicrobial agents and proportionate use of cephems decreased, whereas proportionate use of penicillin increased. The incidences decreased of S. marcescensisolates resistant to flomoxef and ceftazidime, and P. aeruginosa isolates with resistance to ceftazidime and imipenem. Data sharing by distribution of staff information sheets is important for promoting appropriate use of antimicrobial agents and reducing the incidence of bacterial drug resistance.

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract

[in Japanese]

View full abstract