The infection control team (ICT) investigated the healthcare-associated outbreak of acute gastroenteritis due to norovirus that occurred in our hospital from February 1, 2009. Infection precautions (standard precautions and contact precautions) were inadequate to prevent this outbreak and several healthcare staff seemed to be inadequately sterilized against norovirus before the detection of this outbreak. A case-control study was conducted among patients in the A ward of the hospital to determine the risk factors. The study revealed statistical significance regarding wheelchair-dedicated bathroom usage (multivariable logistic regression analyses: OR 5.302, 95% CI 1.376-20.433, p=0.015). The usage of wheelchairs was suggested to be associated with norovirus infections. We concluded that staff should adhere to infection precautions when they deal with patients, dispose of waste, and fully sterilize the contaminated environment vigorously. We recommended that the hospital should separate infected patients from uninfected patients, particularly in terms of the usage of bathrooms and wheelchairs, and sterilize bathrooms and wheelchairs after every use by patients.
An acid or heat preprocessing step or a selective isolation agar is required for the Legionella culture test, since the test sample may contain various other bacteria. However, miscellaneous bacterial growth is sometimes not possible to control even with such precautions. Many Legionella-test manuals indicate that isolated Legionella colonies are characterized by different-sized grayish-white moist look with the slight acidic odor peculiar to Legionella. However, in the actual test, Legionella colonies are often difficult to distinguish from other bacteria in presence of many similar-looking colonies. Therefore, we suggest a colony-observation method which is more precise and simple. The characteristic outward structures (cut-glass like or mosaic like appearance) of Legionella spp. were observed under a stereo microscope with oblique illumination over the growing culture on the isolation agar. Legionella spp. could be distinguished from other bacteria and efficiently obtained using this observational method. In addition, bacteria count was easy and extremely accurate with this method. In this study, 13 serogroups of L. pneumophila and 17 types of other Legionella spp. were detected efficiently by this method from environmental samples. Since the same features were observed in the L. pneumophila serogroup 1, which was detected most frequently in Legionella pneumonia patients, this observational method is one of the most effective test methods for regular monitoring of environmental water or investigations of infection or contamination sources.
The glycopeptide antibiotics vancomycin (VCM) and teicoplanin (TEIC), and the aminoglycoside antibiotic arbekacin (ABK) are considered to be effective for the treatment of methicillin-resistant Staphylococcus aureus (MRSA). Since these anti-MRSA drugs have narrow therapeutic indexes, therapeutic drug monitoring (TDM) is helpful for the optimal management of anti-MRSA chemotherapy based on pharmacokinetics-pharmacodynamics (PK-PD) theory. Thus, we began PK-PD theory-based interventions with TDM on anti-MRSA drug use from 2005 in our hospital. We analyzed dosing methods and outcomes of 157 patients treated with anti-MRSA drugs in 2004 (without intervention), and in 2005 and 2006 (with intervention). After the beginning of the pharmaceutical interventions, the proportion of patients receiving TDM-based treatment (TDM patients) was increased (2% in 2004 and 55% in 2006), and was associated with reduced mean dosing periods of VCM, increased execution rate of loading dose of TEIC, and prolonged dosing interval without changes in the daily dose of ABK. Among the patients treated with anti-MRSA drugs, the clinical effectiveness in TDM patients was 93.0%, which was higher than 68.4% in non-TDM patients. These results suggest that pharmaceutical intervention based on PK-PD theory with TDM could promote optimization of the dosing regimen of anti-MRSA drugs, leading to more effective anti-MRSA chemotherapy.
The rate of carbapenem-resistant Pseudomonas aeruginosa has risen in our hospital. We thought that the increase in the amount used of carbapenems was tied to the rise in carbapenem-resistant P. aeruginosa. Therefore, we introduced a notification policy of specific antimicrobial usage in January 2006. The notification policy has been compulsory since August 2006. We investigated the change in the amount used of specific antimicrobial agents and the amount used of carbapenems, and monitored the rate of carbapenem-resistant P. aeruginosa among inpatients. After the notification policy became compulsory, 99.6% of new uses were submitted for notification. The amount used of a specific antimicrobial agent decreased by 62.7% from 2005 to August 2006-July 2007. Antimicrobial use density of carbapenems decreased by 59.1%, from 23.4 in 2005 to 9.6 in August 2006-July 2007. In order to assess the rate of resistant P. aeruginosa among inpatients, the rate of resistant samples was collected after the first five days of hospitalization. The rate of imipenem-resistant P. aeruginosa decreased from 28% in 2005 to 13% in 2008 (p<0.05). The rate of meropenem-resistant P. aeruginosa decreased from 21% in 2005 to 9% in 2008 (p<0.05). Introduction of the compulsory notification policy of specific antimicrobial usage reduced the rate of carbapenem-resistant P. aeruginosa among inpatients.
A food-borne disease outbreak due to norovirus contamination of the hospital food preparation system occurred in our hospital in December, 2006. Out of 105 affected individuals in total, there were 75 primary cases including 70 confirmed and 5 suspected cases, and 30 secondary cases including 8 confirmed and 22 suspected cases. Eleven of the 30 cases of secondary infection including the suspected cases were in-patients, and 19 cases were staff including students. Eleven of the 19 affected staff were nursing staff (2 confirmed cases and 9 suspected cases). The number of nursing staff in contact with the vomit and diarrhea from the patients or the contaminated environment and linen was 61 of 360 who answered our questionnaire survey. Of these 61 affected nursing staff, one confirmed case and one suspected case were diagnosed as food-borne disease, but no relationship was found between contact with vomit and diarrhea or the use of personal protective equipment, and the onset of disease. Such exposure risk was not observed in this outbreak although the exposure risk associated with the processing of the vomit is assumed to be high due to the inhalation of droplets and particles.
Surveillance of dominant bacterial species isolated in our hospital from March 2005 to July 2007 was examined and the resistance rate was determined. PISP and RSP were isolated at high frequencies of 62.0-85.7%. MRSA and BLNAR Haemophilus influenzae were subsequently isolated at frequencies of 30.2-58.6% and 4.9%-35.5%, respectively. The frequencies of other resistant bacteria were under 5%. ESBL-producing Escherichia coli was isolated at a frequency of 4.4%. Half of the ESBL-producing strains were isolated from outpatients, and 6.8% of the strains were present at the time of hospital admission. The findings of this surveillance indicate that it is necessary to pay careful attention to the trends of resistant bacteria such as PRSP, MRSA, BLNAR, and ESBL-producing strains. S. aureus and S. pneumoniae infections require prevention and treatment as MRSA and PRSP, respectively, until the findings of antimicrobial susceptibility tests are known.
Activities to improve the compliance for hand hygiene using an alcohol-based hand rub were evaluated by measuring the amount used of scrub disinfectant, liquid soap, and alcohol-based hand rub, and the number of hospitalized patients in whom MRSA was newly detected. As a result, the consumption of alcohol-based hand rub in hospital wards and outpatient section has increased annually, and the consumption in 2007 increased significantly compared to that in 2005 (hospital wards 45.2%, outpatient section 64.5%). The number of hospitalized patients in whom MRSA was newly detected was 10.3 cases/10,000 patient days in 2005, 9.8 cases/10,000 patient days in 2006, and 8.8 cases/10,000 patient days in 2007, and tended to decrease annually. These findings suggested that our approach will contribute to improvement in the compliance of hand hygiene with alcohol-based hand rub in the hospital wards and outpatient section, and were effective in reducing the number of new MRSA infections.
A nationwide hospital survey was undertaken to describe infection control system and urinary catheter care practice in Japan. Questionnaires were mailed to all large hospitals (≧400 beds) and one of four small to medium hospitals (100-399 beds) selected by systematic sampling between October and November, 2007. A chief nurse at the internal medicine unit and surgical unit at each hospital was requested to fill out the anonymous questionnaire, asking for the characteristics of the hospital, urinary catheter care, and educational needs for catheter care. Weighting was used for analysis. Of the selected hospitals in the directory, 1650 hospitals had valid addresses. The overall response rate was 40%. In regard to the infection control system, 82% of the respondents had infection control teams, and 36% had full-time or full-time equivalent infection control practitioners. The prevalence of catheter use was approximately 15%, and 59% used preconnected closed drainage systems. In regard to the violation of catheter care guidelines, 51% of the respondents reported practicing bladder washouts, and 29% reported disconnecting the catheter and drainage tube while bathing the patient. Violations of standard precautions were also reported, such as not changing gloves between patients (34%) and sharing urinals among patients (51%). The current study suggests the needs for strengthening infection control systems and improving continuing education to implement correct catheter care and standard precautions.