Antiviral Resistance in Human Cytomegalovirus Due to UL54 Mutations Without UL97 Mutations / 대한임상미생물학회지

Background@#The concurrent detection of human cytomegalovirus (CMV) with UL97 and UL54 mutations is crucial for prescribing adequate antiviral treatment when drug-resistant CMV infection is suspected. We investigated the frequency of resistance-conferring mutations among patients with persistent or recurrent CMV infection and further reviewed the subgroup with UL54 mutations without UL97 mutations. @*Methods@#Patients with persistent or recurrent CMV infection after 4 weeks of treatment with ganciclovir or foscarnet were consecutively enrolled between November 2012 and May 2019.The direct sequencing of UL97 and UL54 was performed to detect resistance mutations in CMV. @*Results@#A total of 101 sequencing datasets were obtained from 65 enrolled patients.CMV UL97 and UL54 mutations were detected in 15.4% (10/65) and 9% (6/65) of patients, respectively. The CMV retrieved from two patients (3%) had mutations in both genes. Four patients with CMV UL54 mutations alone had a history of haploidentical peripheral blood stem cell transplantation, and foscarnet was administered for over 4 weeks to these patients; 21.5% of patients had suspected resistant CMV infection with either UL97 or UL54 mutations. @*Conclusion@#In this study, CMV UL54 mutations but not UL97 mutations were found in patients subjected to prolonged foscarnet administration for CMV disease.

Epidemiologic Linkage of COVID-19Outbreaks at Two University-affiliated Hospitals in the Seoul Metropolitan Area in March 2020

Background@#Coronavirus disease 2019 (COVID-19) outbreaks emerged at two universityaffiliated hospitals in Seoul (hospital A) and Uijeongbu City (hospital S) in the metropolitan Seoul area in March 2020. The aim of this study was to investigate epidemiological links between the outbreaks using whole genome sequencing (WGS) of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). @*Methods@#Fifteen patients were enrolled in the study, including four non-outbreak (A1–A4) and three outbreak cases (A5–A7) in hospital A and eight cases (S1–S8) in hospital S. Patients' hospital stays, COVID-19 symptoms, and transfer history were reviewed. RNA samples were submitted for WGS and genome-wide single nucleotide variants and phylogenetic relationships were analyzed. @*Results@#The index patient (A5) in hospital A was transferred from hospital S on 26 March.Patients A6 and A7 were the family caregiver and sister, respectively, of the patient who shared a room with A5 for 4 days. Prior to transfer, A5 was at the next bed to S8 in the emergency room on 25 March. Patient S6, a professional caregiver, took care of the patient in the room next to S8's room for 5 days until 22 March and then S5 for another 3 days.WGS revealed that SARS-CoV-2 in A2, A3, and A4 belong to clades V/B.2, S/A, and G/B.1, respectively, whereas that of A5–A7 and S1-S5 are of the V/B.2.1 clade and closely clustered. In particular, SARS-CoV-2 in patients A5 and S5 showed perfect identity. @*Conclusion@#WGS is a useful tool to understand epidemiology of SARS-CoV-2. It is the first study to elucidate the role of patient transfer and caregivers as links of nosocomial outbreaks of COVID-19 in multiple hospitals.

Emergence of optrA-Mediated Linezolid-Nonsusceptible Enterococcus faecalis in a Tertiary Care Hospital

This study investigated resistance mechanisms and epidemiology of emerging linezolid-nonsusceptible Enterococcus faecalis (LNSEF) in a tertiary care hospital. LNSEF isolated from clinical samples were collected from November 2017 to June 2019. The isolates were investigated for linezolid resistance and the associated molecular mechanisms, including mutations of 23S rRNA domain V and acquisition of the cfr or optrA resistance gene. We used pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing for the molecular typing of the isolates. Among 4,318 E. faecalis isolates, 10 (0.23%) were linezolid-nonsusceptible. All LNSEF isolates were optrA-positive and cfr-negative. Of these isolates, five were sequence type (ST) 476, two ST585, one ST16, one ST16-like, and one ST480. Six LNSEF isolates obtained in the first year clustered to three types in the PFGE analysis: two ST476 isolates of type A, two ST585 isolates of type B, and two ST16 or ST16-like isolates of type C. Seven cases were of community-onset and three were hospital acquired, but total of eight were healthcare-associated including five community-onset. None of the patients had a history of linezolid treatment, and in one patient, we detected linezolid-susceptible E. faecalis one month before LNSEF detection. In conclusion, heterogenous clones of optrA-positive LNSEF emerged in the hospital mainly via community-onset.

A Case of Chronic Strongyloidiasis with Recurrent Hyperinfection

Strongyloides stercoralis is an intestinal nematode that often causes chronic diarrhea and may develop severe complicated form of hyperinfection or disseminated infection in immunocompromised patients. Here, we report a case of recurrent strongyloidiasis presenting with pulmonary and meningeal involvement. A 55-year-old male diagnosed with pancreatic cancer 4 months ago was admitted due to chronic diarrhea, abdominal pain, and weight loss for 2–3 months. He had been treated with albendazole for chronic recurrent strongyloidiasis 13 years ago and again 2 years ago. He developed sepsis of Klebsiella pneumoniae and Escherichia coli on Days 3 and 7, respectively, and then meningitis of E. coli on Day 42. Strongyloidiasis was diagnosed by detection of abundant filariform larvae in sputum specimens on Day 15. He was treated for disseminated strongyloidiasis with albendazole and ivermectin for five weeks until clearance of larvae was confirmed in sputum and stool specimens. Laboratory diagnosis is important to guide appropriate treatment and to prevent chronic and recurrent strongyloidiasis.