We isolated 66 methicillin-resistant Staphylococcus aureus (MRSA) strains from the blood culture specimens of patients admitted to our hospital between 2015 to 2019. The strains were divided into staphylococcal cassette chromosome mec (SCCmec) type I, type IIa, or type IV by PCR-based open reading frame typing (POT). We defined SCCmec type I (n=2) and type IIa (n=25) as hospital-acquired MRSA (HA-MRSA), and type IV (n=39) as community-acquired MRSA (CA-MRSA), and analyzed the differences between HA-MRSA and CA-MRSA in terms of the patient backgrounds, laboratory data, and antimicrobial susceptibility. Analysis of the yearly changes in the MRSA isolation rates showed an annual increase in the rate of CA-MRSA isolation. There were no significant differences in the patient backgrounds or laboratory data between HA-MRSA and CA-MRSA. Antimicrobial susceptibility testing revealed that the HA-MRSA strains were significantly more resistant to the antibiotics tested than CA-MRSA (p< 0.01). We performed a receiver-operating characteristic (ROC) curve analysis based on the minimum inhibitory concentrations (MICs) of each antibiotic for accurate discrimination between HA-MRSA and CA-MRSA. The area under the curve (AUC) for imipenem/cilastatin (IPM) was the highest (AUC=0.946), and that for the combination of clindamycin (CLDM) plus IPM was 0.996, significantly higher than that for IPM alone (p=0.036). These results indicate that while it was difficult to distinguish between HA-MRSA and CA-MRSA by the patient background factors and laboratory data, antimicrobial susceptibility testing was useful for discriminating between HA-MRSA and CA-MRSA.

A modified serological assay was conducted for investigating the epidemiology of Yersinia pseudotuberculosis infection. This assay was based on agglutination of heat-treated Y. pseudotuberculosis O antigens of serotypes O: 1-O: 7, O: 10 and O: 15. The diagnostic titer was set at ≥1: 160 dilution. A total of 253 serum samples collected from 128 subjects, most of whom were pediatric patients, were examined by the modified method. Forty subjects (31.3%) were seropositive for a single O antigen. The serotype O: 2 was the most common serotype, found in 17 subjects (42.5%). The seropositivity rate did not differ between the suspected Kawasaki disease group (43.5%) and suspected Y. pseudotuberculosis infection group (33.0%). Positivity for the serotype O: 10 was only observed in the former group, and that for serotypes O: 3 and O: 6 only in the latter group. As for clinical symptoms, the frequencies of erythema, skin peeling, and strawberry tongue were significantly higher in the seropositive group than in the seronegative group (p< 0.05). The concordance rate of the results of antibody measurement between the modified method used in this study and the previously used method using live bacterial antigens was 92.2%. In culture-positive cases, both methods yielded positive results. Since serum absorption by Salmonella serogroup O: 4 or O: 9 cells, known as cross reaction with Y. pseudotuberculosis serotype O: 2 or O: 4, respectively, showed a false-negative result in six culture-positive subjects, the absorption process was excluded from the modified method.

We conducted a drug use investigation of an adsorbed 13-valent pneumococcal conjugate vaccine (hereafter, PCV13) in a group of elderly aged ≥65 years, to examine the actual state of use of PCV13 and its safety for 28 days after the inoculation.

A total of 684 subjects (females 56.3%) with an average age (SD) of 76.9 (7.3) years were included in the safety analysis. Almost all of the subjects had received intramuscular inoculation in the upper arm, while four subjects had received subcutaneous inoculation. None of the subjects had received multiple doses of PCV13. Of the 684 subjects, 80 (11.7%) had 123 adverse reactions (ARs). The most frequently reported ARs (incidence ≥3%) were vaccination-site swelling (n = 35, 5.1%), vaccination-site erythema (n = 34, 5.0%), and vaccination-site pain (n = 34, 5.0%). Most of the ARs (90.0%) were mild. Of the 127 subjects with altered immunocompetence, 19 (15.0%) had 40 ARs. Of the 37 subjects who had concurrently received the influenza vaccine, 3 (8.1%) experienced 7 ARs. Of the 267 subjects with a history of PPSV23 vaccination, 28 (10.5%) developed 43 ARs. No risk factors for any of the ARs were found in this study.

We concluded that the PCV13 vaccine was appropriate for use in the elderly and the survey revealed no additional clinically important concerns about the safety of the vaccine in daily practice.

The reported major adverse reactions to COVID-19 vaccination are fever, headache, and malaise, but the possibility of other adverse effects should be considered. We encountered a patient who developed facial nerve paralysis with aseptic meningitis after COVID-19 vaccination. The patient was clinically diagnosed as having Ramsay Hunt syndrome, but there is the possibility that the vaccination contributed to re-activation of the varicella-zoster virus. Immediate treatment should be undertaken for facial nerve paralysis as well as critical anaphylactic shock, and careful observations should be made for the possibility of delayed adverse reactions, such as facial paralysis, to COVID-19 vaccination.

Human granulocytic anaplasmosis is a febrile illness caused by Anaplasma phagocytophilum, an intracellular bacterium transmitted by ticks that is mainly prevalent in the United States and Europe. Five cases have been reported from Japan. A 63-year-old man was admitted to our hospital with a 5-day history of high fever. The patient frequently worked in mountainous areas and reported having felt an insect bite or thorn stick in his right leg some days earlier. Laboratory investigations showed increased serum levels of C-reactive protein, total bilirubin and the hepatobiliary enzymes. The patient was immediately started on treatment and received minocycline 200 mg/day for 8 days and ceftriaxone sodium 2 g/day for 6 days for a suspected diagnosis of rickettsiosis and acute cholangitis, and recovered by eight days. Eventually, on the basis of the results of serum tests for antibodies to tick-borne pathogens, which revealed increase in antibody titers to A. phagocytophilum in paired sera, the patient was diagnosed as having anaplasmosis. Different from the 5 previously reported cases from Japan, this patient was a habitual drinker and cholangitis was suspected as a complication of anaplasmosis in him. Herein, we report an unusual presentation and severe disease complications of human granulocytic anaplasmosis in a habitual drinker.