End-of-season outbreaks of nosocomial influenza caused by waning vaccine immunity.

The waning of vaccine protection may be responsible for outbreaks toward the end of the influenza season. Three of five outbreaks occurred at the beginning of April following an interval of >100 days from the date of vaccination; the reported index case was a nurse or office worker, and >50% of those affected were healthcare workers. The results are consistent with intra-seasonal waning of vaccine immunity that resulted in outbreaks at the end of season.

Prevalence and characteristics of methicillin-resistant Staphylococcus aureus colonization among healthcare professionals in a university hospital in Japan.

BACKGROUND: Asymptomatic carriers of methicillin-resistant Staphylococcus aureus (MRSA) are important sources of nosocomial transmission. MRSA may be transmitted from hospitalized patients to healthcare professionals and vice versa. METHODS: The prevalence of MRSA colonization among forty-five healthcare professionals in a Japanese hospital was determined by performing surveillance cultures to identify unrecognized carriers of MRSA. All MRSA isolates were evaluated using multilocus sequence typing (MLST) to identify the transmission routes. RESULTS: The proportion of MRSA colonization was significantly higher in healthcare professionals (11.1%) than in community residents (0.72%; P < 0.0001) or admission case (2.5%; P = 0.018). MLST analysis revealed that both the ST8 and ST764 strains were identified in residents, patients, and healthcare professionals. MRSA colonization was more frequently observed among physicians (4/13; 31%) than nurses (1/32; 3%) (P = 0.020). CONCLUSION: Multilocus sequence typing results suggest that ST8 and ST764 are involved in the occurrence of nosocomial MRSA infections. These findings emphasize the necessity for the effective education of physicians to prevent MRSA transmissions.

Transmission of methicillin-resistant Staphylococcus aureus in an acute care hospital in Japan.

BACKGROUND: Asymptomatic carriers of methicillin-resistant Staphylococcus aureus (MRSA) are important sources of nosocomial transmission. However, the route of transmission of MRSA is not completely understood. The purpose of this study was to calculate MRSA transmission rates in a hospital with a high MRSA infection/colonization density and inadequate hand hygiene compliance. METHODS: The prevalence of MRSA colonization among 157 patients at the time of admission to and discharge from a medical school hospital in Japan was determined by performing surveillance cultures. All MRSA isolates were evaluated using multilocus sequence typing (MLST) to identify the transmission routes. RESULTS: Methicillin-resistant S. aureus was prevalent in 1.9% of our study population. MRSA was acquired during hospitalization at a rate of 4.0/1000 patient-days. At discharge, 5.1% of the patients exhibited MRSA colonization; this was significantly higher than the prevalence noted upon admission (P < 0.001). MLST documented three possible nosocomial transmission events. MRSA colonization was detected using surveillance cultures prior to being identified by conventional, clinically oriented examinations. CONCLUSIONS: Multilocus sequence typing results suggested that patients who were colonized with MRSA acquired it during hospitalization. These results reinforce the importance of infection control for preventing nosocomial MRSA transmission in hospitalized patients.

Booster influenza vaccination confers additional immune responses in an elderly, rural community-dwelling population.

This study aimed to examine the effects of a booster vaccination in elderly people using 2 doses of trivalent inactivated influenza vaccine during the 2012-2013 influenza epidemic. Seroprotection rates against the A(H1N1)pdm09 strain in younger elderly people (aged 61-75 years) and the A(H3N2) and B strains in both younger elderly people (aged 61-75 years) as well as very elderly people (aged 76-102 years) did not decrease at 22 weeks after vaccination. This approach confers long-lasting antibody responses and may be useful in clinical practice.

Prevalence and characteristics of methicillin-resistant Staphylococcus aureus in community residents of Japan.

BACKGROUND: To implement effective precautions to avoid methicillin-resistant Staphylococcus aureus (MRSA) nosocomial infections, it is important to clarify when, how, and from whom MRSA was transmitted to the patients. However, MRSA strains obtained from outpatient population were not analyzed, and the transmission routes of MRSA in the community are not completely understood. The purpose of this study was to clarify whether MRSA is spreading in community settings or whether MRSA transmission still occurs only in healthcare institutions. METHODS: Surveillance cultures of 1274 residents living in a community were performed in two different areas, Kochi and Osaka prefectures of Japan. All isolated MRSA strains were evaluated using multilocus sequence typing (MLST) to clarify the transmission routes of MRSA. The results were compared with those of inpatients. Moreover, written questionnaires and medical records were analyzed. RESULTS: Analysis of surveillance cultures from residents living in the community in Japan revealed an MRSA colonization rate of 0.94%. The proportion of MRSA to S. aureus colonization was 2.6% in the 310 residents, which was significantly lower than in the 393 hospitalized patients (63.1%; P < .0001). MRSA strains in residents are different from the endemic strains in the hospitalized patients. Previous hospital admission is a risk factor for MRSA infection of the endemic strain in hospital. CONCLUSIONS: Methicillin-resistant Staphylococcus aureus colonization in community setting is rare in Japan. MLST results suggest that some MRSA strains are moving to the community through previous hospital admissions; however, MRSA is not spreading in community settings.

Continued direct observation and feedback of hand hygiene adherence can result in long-term improvement.

BACKGROUND: Hospital-wide multifaceted approaches can improve hand hygiene compliance in health care workers. However, the true effects of monitoring and feedback interventions are not clear. METHODS: Hand hygiene compliance was evaluated by applying direct observation techniques over 5 years (2005-2009) in a tertiary care general hospital in Japan. The observed results were periodically reported as feedback to the health care workers. RESULTS: The overall hand hygiene compliance rate increased from 50.8% in 2005 to 61.0% in 2006 (P = .004) and was sustained at approximately 60% through the completion of the study. The compliance rate for the indication before entering the room increased from 2005 to 2009 (P = .005). The compliance rates for 4 before patient contact indications increased from 2005 to 2009 (P = .002). The combined compliance rate for the 6 indications with the lowest compliance rates in 2005 increased from 2005 to 2009 (P = .001). CONCLUSIONS: Direct observation and feedback methods are effective strategies that resulted in a long-lasting improvement in hand hygiene compliance that was sustained over 5 years through the completion of the study. Focusing on the procedures with high baseline noncompliance rates can be an effective way to improve the overall compliance.

Prevaccination antibody titers can estimate the immune response to influenza vaccine in a rural community-dwelling elderly population.

Influenza and its complications are related to increased morbidity and mortality in elderly persons. Influenza vaccination is an important strategy to minimize the excess morbidity and mortality caused by influenza infection. Influenza epidemics start in November and continue to March in the next year, but it is not clear if the immunization-induced antibody titer lasts throughout the influenza season. One hundred eighty-two rural community-dwelling elderly persons older than 61 years were immunized with one dose of influenza vaccine in the 2005-2006 influenza season, and the antibody response after vaccination was investigated. Both the antibody titers and seroprotection rates were significantly higher four weeks after the vaccination but decreased markedly at 22 weeks after the vaccination. Analysis of the factors affecting the antibody response showed that those who have a low antibody titer before vaccination ('seronegative') do not acquire enough antibody with one dose of influenza vaccine. Neither age nor vaccination in the previous year was related to the antibody response after vaccination. These findings suggest that future clinical trials should be performed to determine if a second booster vaccination maintains the titer.