Severe fever with thrombocytopenia syndrome (SFTS) is an acute febrile illness characterized by fever, leukopenia, thrombocytopenia, and gastrointestinal symptoms such as diarrhea, nausea, and vomiting resulting from infection with the SFTS virus (SFTSV). The SFTSV is transmitted to humans by tick bites, primarily from Haemaphysalis longicornis, Amblyomma testudinarium, Ixodes nipponensis, and Rhipicephalus microplus. Human-to-human transmission has also been reported. Since the first report of an SFTS patient in China, the number of patients has also been increasing. The mortality rate of patients with SFTS remains high because the disease can quickly lead to death through multiple organ failure. In particular, an average fatality rate of approximately 20% has been reported for SFTS patients, and no treatment strategy has been established. Therefore, effective antiviral agents and vaccines are required. Here, we aim to review the epidemiology, clinical manifestations, laboratory diagnosis, and various specific treatments (i.e., antiviral agents, steroids, intravenous immunoglobulin, and plasma exchange) that have been tested to help to cope with the disease.

Scrub typhus is a mite-borne bacterial infection of humans caused by Orientia tsutsugamushi that causes a generalized vasculitis that may involve the tissues of any organ system. The aim of this study was to identify factors associated to severe complications from scrub typhus.

Eschar is an important finding for the diagnosis of scrub typhus. The IFA test for possible scrub typhus was performed. The presence or absence of eschar was thoroughly examined. Among the 176 scrub typhus cases confirmed by IFA, 162 (92.0%) cases had eschar; 128 patients (79.5%) had eschars on the front of the body. Eschars were primarily detected in males within 30 cm below the umbilicus (19 patients, 35.8%). Distributions on the lower extremities and the front chest above the umbilicus were 22.6% (12 patients) and 20.8% (11 patients), respectively. A different pattern was seen in females. The most prevalent area was the front chest above the umbilicus, which accounted for 40.7% (44 patients) of all the detected eschars. Our study is the first report of a schematic diagram that shows the differences between the males and females with respect to eschar location in scrub typhus patients.

Methicillin-resistant Staphylococcus aureus (MRSA), originally restricted to hospitals, has emerged as a significant pathogen in the community. Although MRSA accounts for over 60% of S . aureus in tertiary hospitals in Korea, little is known about the epidemiology of community-associated MRSA (CA-MRSA). From January to July 2005, a hospital laboratory-based survey was conducted in seven community-based or tertiary hospitals. The medical records and Health Insurance Review Agency databases were reviewed and MRSA isolated from patients without apparent risk factors was defined as CA-MRSA. Susceptibilities to 12 antibiotics were tested by the disc diffusion method. SCC mec typing, Panton–Valentine leucocidin (PVL) gene detection and multilocus sequence typing (MLST) were performed according to published protocols. Of 3251 S . aureus , 1900 (58.4%) were MRSA. CA-MRSA accounted for 112 (5.9%) of the MRSA. Of the 112 CA-MRSA isolates, 27 and 33 were found to be pathogens and colonizers, respectively. Fifty-two isolates from the patients with chronic otitis media were classified as ‘undetermined’. Most of the 27 CA-MRSA patients had skin and soft tissue infections or acute ear infections. None of the patients died during the study period. Among 72 isolates tested, 64% were multidrug-resistant. SCC mec type IVa was the most common type among the colonizers and pathogens. On MLST analysis, ST72 was predominant, but ST5 and ST239 were prevalent in the ‘undetermined’ group. None possessed the PVL gene. Despite MRSA-endemic hospital settings, CA-MRSA infections are not common in Korea. A new clone of CA-MRSA, ST72-SCC mec type IVa without the PVL gene, is the most common form.

Tariq M, et al. Infect Chemother. 2022 Feb;54:e8. https://doi.org/10.3947/ic.2021.0148

Orientia tsutsugamushi is the causative agent of scrub typhus. For the diagnosis of scrub typhus, we investigated the performances of conventional PCR (C-PCR), nested PCR (N-PCR), and real-time quantitative PCR (Q-PCR) targeting the O. tsutsugamushi -specific 47-kDa gene. To compare the detection sensitivities of the three techniques, we used two template systems that used plasmid DNA (plasmid detection sensitivity), including a partial region of the 47-kDa gene, and genomic DNA (genomic detection sensitivity) from a buffy coat sample of a single patient. The plasmid detection sensitivities of C-PCR, N-PCR, and Q-PCR were 5 × 10 ⁴ copies/μl, 5 copies/μl, and 50 copies/μl, respectively. The results of C-PCR, N-PCR, and Q-PCR performed with undiluted genomic DNA were negative, positive, and positive, respectively. The genomic detection sensitivities of N-PCR and Q-PCR were 64-fold and 16-fold (crossing point [Cp], 37.7; 426 copies/μl), respectively. For relative quantification of O. tsutsugamushi bacteria per volume of whole blood, we performed real-time DNA PCR analysis of the human GAPDH gene, along with the O. tsutsugamushi 47-kDa gene. At a 16-fold dilution, the copy number and genomic equivalent (GE) of GAPDH were 1.1 × 10 ⁵ copies/μl (Cp, 22.64) and 5.5 × 10 ⁴ GEs/μl, respectively. Therefore, the relative concentration of O. tsutsugamushi at a 16-fold dilution was 0.0078 organism/one white blood cell (WBC) and 117 organisms/μl of whole blood, because the WBC count of the patient was 1.5 × 10 ⁴ cells/μl of whole blood. The sensitivities of C-PCR, N-PCR, and Q-PCR performed with blood samples taken from patients within 4 weeks of onset of fever were 7.3% (95% confidence interval [CI], 1.6 to 19.9), 85.4% (95% CI, 70.8 to 94.4), and 82.9% (95% CI, 67.9 to 92.8), respectively. All evaluated assays were 100% specific for O. tsutsugamushi . In conclusion, given its combined sensitivity, specificity, and speed, Q-PCR is the preferred assay for the diagnosis of scrub typhus.