Detailed analysis of low temperature inactivation of respiratory syncytial virus.

Our previous findings indicated that many respiratory syncytial virus (RSV) isolates are unstable at 4 °C compared to 20 °C. Some of the strains completely lose infectivity after 24 h at 4 °C. This study analyzed the inactivation process at 4 °C using a representative strain, RSV/Sendai/851/13. After 24 h of storage at 4 °C, the virus was completely inactivated but retained its ability to attach to and to be taken into host cells. It suggested a reduced fusion ability between the viral and cellular membranes. During storage at 4 °C, the RSV fusion (F) protein underwent a conformational change and was no longer recognized by pre-fusion form-specific antibodies. When the RSV/Sendai/851/13 strain was passaged at 4 °C, a variant with an amino acid substitution, I148T, in the F protein fusion peptide was selected. Also, an amino acid change in G protein demonstrating stability at low temperatures was obtained. These results show that the inactivation of RSV at 4 °C is due to the loss of membrane fusion activity in the F protein, which cannot maintain its pre-fusion state at 4 °C.

Epidemiologic, clinical, and genetic characteristics of influenza C virus infections among outpatients and inpatients in Sendai, Japan from 2006 to 2020.

BACKGROUND: Influenza C virus is a pathogen that causes acute respiratory illness in children. The clinical information about this virus is limited because of the small number of isolated viruses compared to influenza A or B viruses. METHODS: A total of 60 influenza C viruses were isolated by clinical tests using cell culture methods conducted in one hospital and one clinic during the 15 years from 2006 to 2020. These 60 cases were retrospectively analyzed by comparing outpatients and inpatients. Moreover, isolated viruses were analyzed for genomic changes during the study period. RESULTS: All were younger than 7 years, and 73% of inpatients (19 out of 26) were under 2 years of age. A significant difference was found in the frequency of pneumonia, accounting for 45% and 4% of inpatients and outpatients, respectively. Most of the viruses isolated from 2006 to 2012 belonged to the S/A sublineage of the C/Sao Paulo lineage, but three sublineage viruses, including the S/A sublineage with K190N mutation, S/V sublineage, and C/Kanagawa lineage, have cocirculated since 2014. Moreover, S/A sublineage viruses were undergoing reassortment since 2014, suggesting significant changes in the virus, both antigenically and genetically. Of the 10 strains from patients with pneumonia, 7 were in the S/A sublineage, which had circulated from 2006 to 2012. CONCLUSION: Infants under 2 years of age were more likely to be hospitalized with pneumonia. The genomic changes that occurred in 2014 were suggested to affect the ability of the virus to spread.

Variation in Thermal Stability among Respiratory Syncytial Virus Clinical Isolates under Non-Freezing Conditions.

Virus isolates are not only useful for diagnosing infections, e.g., respiratory syncytial virus (RSV), but can also facilitate many aspects of practical viral studies such as analyses of antigenicity and the action mechanisms of antivirals, among others. We have been isolating RSV from clinical specimens from patients with respiratory symptoms every year since our first isolation of RSV in 1964, and isolation rates have varied considerably over the years. As collected clinical specimens are conventionally stored in a refrigerator from collection to inoculation into cells, we hypothesized that certain storage conditions or associated factors might account for these differences. Hence, we evaluated the thermal stability of a total of 64 viruses isolated from 1998 to 2018 upon storage at 4 °C and 20 °C for a defined duration. Interestingly, and contrary to our current understanding, 22 strains (34%) showed a greater loss of viability upon short-term storage at 4 °C than at 20 °C. Thirty-seven strains (57%) showed an almost equal loss, and only five strains (8%) were more stable at 4 °C than at 20 °C. This finding warrants reconsideration of the temperature for the temporary storage of clinical samples for RSV isolation.

Sternal wound care to prevent infections in adult cardiac surgery patients.

Sternal wound infection post-cardiac surgery is a serious complication that can lead to increased length of stay, substantial financial impact, and increased mortality. The occurrence of sternal wound infections has been reported from 0.4% to 4% of postoperative cardiac surgeries. It is imperative that every heart surgery program implements the best practice to prevent the detrimental effects of sternal wound infections. In an effort to improve the cardiothoracic (CT) surgery program in a community hospital, a decision was made to create a specialty floor including specialized nurses to care for open-heart surgery patients. In October 2010, a group of these nurses formed a working committee to explore ways to improve the overall care of our CT surgery patients. A vision and purpose for this committee were identified: (1) update and improve practice for CT surgery patients utilizing evidence-based standards, (2) successfully disseminate this information to all staff caring for the CT surgery patients, and (3) evaluate the impact of any practice changes on patient outcomes. An initial focus for the committee was to standardize sternal wound care among all staff members on the cardiovascular floors, cardiac care unit, and progressive care unit.

[Genesis of methicillin-resistant Staphylococcus aureus and selective antibacterial injection pressure].

We reported previously that cefazolin was related to an increase in methicillin-resistant Staphylococcus aureus (MRSA) between 1998 and 2000 at Yamagata University Hospital. The incidence of MRSA decreased, however, between 2001 and 2003. We examined the relationship between the use of antibacterial injection and MRSA incidence. MRSA increased in surgical and medical wards between 1998 and 2000, but decreased mainly in surgical wards between 2001 and 2003. We statistically analyed the number of inpatients detected with MRSA (MRSA patients) and the use of antibiotics per month. MRSA patients positively correlated with cephems and carbapenems, the highest positive correlation with cefazolin at a correlation coefficient (R) of 0.45 (p<0.001). In multiple linear regression analysis, cefazolin and carbapenems were chosen as independent variables of a regression equation predicting MRSA patients, during the MRSA decrease and in surgical wards. We thought, it was because carbapenems increased with cefazolin that only cefazolin was chosen as an independent variable during the MRSA increase. We found that the antibiotics as independent variables were associated with about 50% of MRSA by the multiple regression model contribution ratio. Cefazolin was used most for presurgical prophylaxis in surgical wards, and about 20% of surgical wards in medical wards. Carbapenems were use almost equally in surgical and medical wards, but the correlation with MRSA in medical wards was 0.21 (p<0.1) and in surgical wards 0.38 (p<0.005), showing a significant correlation with carbapenems in surgical wards. In conclusion, cefazolin and carbapenems were related to the incidence of MRSA, and carbapenems showed a significant correlation in the presence of cefazolin. This strongly suggests that MRSA is significantly generated when inpatients are given carbapenems after administration of cefazolin.

[Evaluation of great gene variations in methicillin-resistant Staphylococcus aureus--controlled study in 363 strains from 192 patients].

BACKGROUND: We tested a hypothesis that major gene variations of methicillin-resistant Staphylococcus aureus (MRSA) are detectable in a single patient. METHODS: We isolated 363 strains of MRSA in 192 patients diagnosed as having MRSA infection in Yamagata University Hospital. By an established pulsed-field gel electrophoresis method, all strains were analysed by Sma I macrorestriction patterns of genomic DNA. RESULTS: A total of 54 different electrophoresis was observed, (8 major types each of which has 5-8 subtypes). Two or more strains could be isolated in 68 patients. Out of these patients 2-4 different gene variations were detected in a single patient. CONCLUSIONS: Our results suggest that gene variations can be detectable in a single patient and that caution should be paid for diagnosis of MRSA cross infection.

[Relationship between methicillin resistant Staphylococcus aureus from inpatients and parenteral antibiotics].

We examined the relationship between clinical isolates from inpatients, mainly methicillin resistance Staphylococcus aureus (MRSA), and usage of parenteral antibiotics in Yamagata University Hospital and comparison of the relationship of the previous decade and the present. The first period was from 1988 to 1990 in a row, and the second period was from 1998 to 2000 in a row. In the first period, third generation cephems were used much and usage of antibiotics was shifted from latamoxef to flomoxef. Isolations of MRSA were decreased. In the second period, the third generation cephems decreased, cefazolin and the forth generation cephems increased. And also decrease in usage of penicillins was observed. Isolations of MRSA were increased. For further examination of these relation, we studied by statistical analysis the number of MRSA patients and usage of antibiotics per month in the second period. MRSA patients showed positive correlation with cephems and carbapenems, negative correlation with penicillins. In major antibiotics MRSA patients showed positive correlation with cefazolin, negative correlation with piperacillin. In multiple linear regression analysis, MRSA patients calculated multiple regression model including cefazolin. In conclusion, it was suggested that cefazolin related with MRSA. It has been estimated that cefazolin were administered before the appearance of MRSA. It is a possibility that cefazolin related with the appearance or fixation of MRSA.