Novel high-throughput screening method using quantitative PCR to determine the antimicrobial susceptibility of Orientia tsutsugamushi clinical isolates

A case of pulmonary tuberculosis patient complicated with hemorrhagic fever with renal syndrome and scrub typhus in Yunnan, China: a case report

BACKGROUND

Hemorrhagic fever with renal syndrome (HFRS) caused by Orthohantavirus (OHV) and scrub typhus (ST) caused by Orientia tsutsugamushi (OT) are two infectious diseases prevalent in southwest China. Rodents are the natural host and the main source of the two diseases. OT infection to humans is usually resulted from bite of an infective chigger mite on rodents, and OHV is transmitted through contact or inhalation of aerosols and secretions from infected rodent. The use of antibiotics and hormones is crucial for infectious diseases, although the clinical manifestations are not obvious and a definitive diagnosis becomes more difficult in the presence of these drugs. Clinically, fever is the first symptom of these two diseases, and most of them are accompanied by common symptoms such as chills and headaches. The clinical symptoms of these two diseases are very similar and therefore it is not easy to make a differential diagnosis.

CASE PRESENTATION

In this case, a 44-year-old male famer with pulmonary tuberculosis and a history of working in coal transportation was admitted to the hospital because of respiratory symptoms accompanied by fever, headache, and skin rashes on his body. Biochemical and urinalysis revealed the hepatic and renal injury. The subsequent molecular testing confirmed he suffered from HFRS and scrub typhus simultaneously that the serological and clinical diagnosis could not identify the cause of infection before. Such case has not been reported in Yunnan Province before.

CONCLUSION

The clinical diagnosis should be combined with serological and nucleic acid testing approaches for differential diagnosis in areas where HFRS and ST are endemic.

Rapid Methods for Antimicrobial Resistance Diagnostics

Antimicrobial resistance (AMR) is one of the most challenging threats in public health; thus, there is a growing demand for methods and technologies that enable rapid antimicrobial susceptibility testing (AST). The conventional methods and technologies addressing AMR diagnostics and AST employed in clinical microbiology are tedious, with high turnaround times (TAT), and are usually expensive. As a result, empirical antimicrobial therapies are prescribed leading to AMR spread, which in turn causes higher mortality rates and increased healthcare costs. This review describes the developments in current cutting-edge methods and technologies, organized by key enabling research domains, towards fighting the looming AMR menace by employing recent advances in AMR diagnostic tools. First, we summarize the conventional methods addressing AMR detection, surveillance, and AST. Thereafter, we examine more recent non-conventional methods and the advancements in each field, including whole genome sequencing (WGS), matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) spectrometry, Fourier transform infrared (FTIR) spectroscopy, and microfluidics technology. Following, we provide examples of commercially available diagnostic platforms for AST. Finally, perspectives on the implementation of emerging concepts towards developing paradigm-changing technologies and methodologies for AMR diagnostics are discussed.

Scrub Typhus and the Misconception of Doxycycline Resistance

Scrub typhus, a neglected infectious disease caused by the obligate intracellular bacterium Orientia tsutsugamushi, is a major cause of fever across the Asia Pacific region with more than a billion people at risk. Treatment with antibiotics such as doxycycline or chloramphenicol is effective for the majority of patients. In the 1990s, reports from northern Thailand raised a troubling observation; some scrub typhus patients responded poorly to doxycycline, which investigators attributed to doxycycline resistance. Despite the controversial nature of these reports, independent verification was neglected, with subsequent studies speculating on the role of doxycycline resistance in contributing to failure of treatment or prophylaxis. In this review, we have outlined the evidence for drug-resistant Orientia tsutsugamushi, assessed the evidence for doxycycline resistance, and highlight more recent findings unsupportive of doxycycline resistance. We conclude that doxycycline resistance is a misconception, with treatment outcome likely to be determined by other bacterial, host, and pharmacological factors.

History of Tsutsugamushi Disease in Korea

Tsutsugamushi disease or scrub typhus in Korea was first officially reported in foreign soldiers in 1951 and in indigenous persons in 1986. However, the history is further prolonged. The book Dong Ui Bo Gam, published in 1613, described “Soo Dok” (water poisoning), which is similar to tsutsugamushi disease. Further, the term was mentioned in the book Hyang Yak Gu Geup Bang, first published in 1232–1251. During the Japanese colonial rule (1910-1945), Trombicula akamushi was identified in Suwon, Korea, in 1917. Although cases of tsutsugamushi disease in Korea with a murine typhus-like illness and OXK-positivity were reported in 1935, such atypical presentation was not recognized as tsutsugamushi disease. During the Korean War, in 1951, tsutsugamushi disease developed in two British soldiers stationed in the Imjin River, who presented typical features and positive OXK reactions. Indigenous cases have re-emerged since 1986. Thereafter, there were many studies on various aspects of tsutsugamushi disease: epidemiology, vector, small mammals, clinical features and complications, diagnosis, and treatment. Persistence of Orientia tsutsugamushi and its possible recrudescence with pneumonia were reported in 2012 and 2014, respectively.