Case Report: Metagenomic Next-Generation Sequencing Confirmed a Case of Spine Infection with Brucella melitensis in Non-Endemic Area.

Brucellosis is a zoonotic disease caused by Brucella spp., with the highest prevalence found in the northern cities of China. In this case report, we present an occurrence of spinal infection caused by B. melitensis in a 67-year-old man residing in a non-endemic area of southern China. The patient initially presented with chest and back pain, which was not accurately diagnosed and treated at a local hospital. Subsequently, due to worsening pain, he was admitted to our hospital. To determine the cause of the infection, we performed CT-guided aspiration biopsy and collected biopsy tissue for metagenomic next-generation sequencing (mNGS) on the second day of hospitalization. Imaging investigations revealed involvement of the thoracic vertebrae, specifically thoracic 4-7 with the main focus on 5-6, accompanied by stenosis of the intervertebral space. The mNGS results indicated that the spine infection was caused by B. melitensis. The patient's history as a shepherd and a positive Rose Bengal plate test (RBPT) further supported the diagnosis of brucella spondylitis. In order to alleviate pain and restore spinal function, the patient underwent posterior internal fixation of the thoracic spine. Treatment was initiated with cefoperazone/sulbactam, followed by doxycycline. Subsequently, the patient was switched to a combination therapy of rifampicin and doxycycline for a duration of six weeks. The patient responded well to treatment, and his condition remained stable. In conclusion, brucellosis is a common disease that can be easily misdiagnosed. This case report highlights the potential value of mNGS in early and rapid diagnosis. We believe that mNGS can serve as an effective tool to improve the diagnosis of spine infections caused by this pathogen.

Clinical Features, Strain Distribution, Antifungal Resistance and Prognosis of Patients with Non-albicans Candidemia: A Retrospective Observational Study.

PURPOSE: Candida albicans (C. albicans) candidemia has been well reported in previous studies, while research on non-albicans Candida (NAC) bloodstream infections remains poorly explored. Therefore, the present study aimed to investigate the clinical characteristics and outcomes of patients with NAC candidemia. PATIENTS AND METHODS: We recruited inpatients with candidemia from January 2013 to June 2020 in a tertiary hospital for this retrospective observational study. RESULTS: A total of 301 patients with candidemia were recruited in the current study, including 161 (53.5%) patients with NAC candidemia. The main pathogens in NAC candidemia were Candida tropicalis (C. tropicalis) (23.9%), Candida parapsilosis (15.6%) and Candida glabrata (10.3%). Patients with NAC candidemia had more medical admissions (P=0.034), a higher percentage of hematological malignancies (P=0.007), a higher frequency of antifungal exposure (P=0.012), and more indwelling peripherally inserted central catheters (P=0.002) than those with C. albicans candidemia. In a multivariable analysis, prior antifungal exposure was independently related to NAC candidemia (adjusted odds ratio [aOR], 0.312; 95% confidence interval [CI], 0.113-0.859). Additionally, NAC was obviously resistant to azoles, especially C. tropicalis had a high cross-resistance to azoles. However, no significant differences were noted in the mortality rates at 14 days, 28 days and 60 days between these two groups. CONCLUSION: NAC is dominant in candidemia, and prior antifungal exposure is an independent risk factor. Of note, although the outcomes of NAC and C. albicans candidemia are similar, drug resistance to specific azoles as well as cross-resistance frequently occurs in patients with NAC candidemia, and this drug resistance deserves attention in clinical practice and further in-depth investigation.

Neddylation Alleviates Methicillin-Resistant Staphylococcus aureus Infection by Inducing Macrophage Reactive Oxygen Species Production.

Neddylation, a posttranslational modification in which NEDD8 is covalently attached to target proteins, has emerged as an endogenous regulator of innate immunity. However, the role of neddylation in methicillin-resistant Staphylococcus aureus (MRSA) infection remains unknown. In this study, we found that neddylation was activated after MRSA infection in vivo and in vitro. Inhibition of neddylation with MLN4924 promoted injury of liver and kidneys in C57BL/6 mice with MRSA bloodstream infection and increased mortality. Blockade of neddylation, either pharmacologically (MLN4924, DI591) or through the use of Uba3 small interfering RNA, inhibited Cullin3 neddylation and promoted Nrf2 accumulation, thus reducing reactive oxygen species (ROS) induction and bacterial killing ability in mouse peritoneal macrophages. In summary, our findings suggest that activation of neddylation in macrophages plays a critical protective role against MRSA infection by increasing ROS production, partially by signaling through the NEDD8-Cullin3-Nrf2-ROS axis. Furthermore, our results may provide a new non-antibiotic treatment strategy for MRSA infection through targeting of neddylation.

Evolution of tigecycline- and colistin-resistant CRKP (carbapenem-resistant Klebsiella pneumoniae) in vivo and its persistence in the GI tract.

Emergence of carbapenem-resistant Klebsiella pneumoniae (CRKP) strains that also exhibit resistance to tigecycline and colistin have become a major clinical concern, as these two agents are the last-resort antibiotics used for treatment of CRKP infections. A leukemia patient infected with CRKP was subjected to follow-up analysis of variation in phenotypic and genotypic characteristics of CRKP strains isolated from various specimens at different stages of treatment over a period of 3 years. Our data showed that (1) carbapenem treatment led to the emergence of CRKP in the gastrointestinal (GI) tract of the patient, which subsequently caused infections at other body sites as well as septicemia; (2) treatment with tigecycline led to the emergence of tigecycline-resistant CRKP, possibly through induction of the expression of a variant tet(A) gene located in a conjugative plasmid; (3) colistin treatment was effective in clearing CRKP from the bloodstream but led to the emergence of mcr-1-positive Enterobacteriaceae strains as well as colistin-resistant CRKP in the GI tract due to inactivation of the mgrB gene; and (4) tigecycline- and colistin-resistant CRKP could persist in the human GI tract for a prolonged period even without antibiotic selection pressure. In conclusion, clinical CRKP strains carrying a conjugative plasmid that harbors the blaKPC-2 and tet(A) variant genes readily evolve into tigecycline- and colistin-resistant CRKP upon treatment with these two antibiotics and persist in the human GI tract.

Detection of plasmid-mediated IMP-1 metallo-beta-lactamase and quinolone resistance determinants in an ertapenem-resistant Enterobacter cloacae isolate.

OBJECTIVE: To investigate the mechanism of carbapenem resistance and the occurrence of plasmid-mediated quinolone resistance determinants qnr and aac(6')-Ib-cr in a clinical isolate of Enterobacter cloacae. METHODS: An ertapenem-resistant E. cloacae ZY106, which was isolated from liquor puris of a female gastric cancer patient in a Chinese hospital, was investigated. Antibiotic susceptibilities were determined by agar dilution method. Conjugation experiments, isoelectric focusing, polymerase chain reaction (PCR), and DNA sequence analyses of plasmid-mediated carbapenemases and quinolone resistance determinants were preformed to confirm the genotype. Outer membrane proteins (OMPs) were examined by urea-sodium dodecyl sulfate-polyacrylamide gel electrophoresis (Urea-SDS-PAGE). RESULTS: Minimum inhibitory concentrations (MICs) of imipenem, meropenem, and ertapenem for ZY106 were 2, 4, and 16 microg/ml, respectively. Conjugation studies with Escherichia coli resulted in the transfer of significantly reduced carbapenem susceptibility. ZY106 produced IMP-1 metallo-beta-lactamase and CTX-M-3 extended-spectrum beta-lactamase, and E. coli transconjugant produced IMP-1. Plasmid-mediated quinolone resistance determinant qnrS1 was detected in ZY106. Transfer of the qnrS1-encoding-plasmid into E. coli by conjugation resulted in intermediate resistance to ciprofloxacin in E. coli transconjugant. Urea-SDS-PAGE analysis of OMPs showed that ZY106 lacked an OMP of approximately 38 kDa. CONCLUSION: It is the first IMP-1-producing Enterobacteriaceae in China and the first report of a clinical isolate that harbors both blaIMP and qnrS genes as well. The blaIMP-1, blaCTX-M-3, and qnrS1 are encoded at three different plasmids. IMP-1 combined with the loss of an OMP possibly resulted in ertapenem resistance and reduced imipenem and meropenem susceptibility in E. cloacae.