Giant splenic cyst complicated by infection due to Salmonella enterica serovar Livingstone in a previously healthy adolescent male: a case report.

BACKGROUND: Splenic cyst complicated by non-typhoid Salmonella infection is rare in healthy individuals in the era of antibiotics. Salmonella enterica subsp. enterica serovar Livingstone causing infection of giant splenic cyst has not been previously reported. CASE PRESENTATION: We report a case of giant splenic cyst (maximum diameter, 21 cm) complicated with Salmonella Livingstone infection, which resulted in splenic abscess, in a 16-year-old previously healthy adolescent male. The splenic abscess was successfully treated with ultrasonography-guided percutaneous drainage and antimicrobial therapy. CONCLUSION: Infection of splenic cyst may be caused by S. Livingstone in immunocompetent individuals. This case may help clinicians to raise awareness towards splenic abscess and highlights the importance of drainage and antimicrobial agents to avoid splenectomy.

Genome-Based Taxonomy of Brevundimonas with Reporting Brevundimonas huaxiensis sp. nov.

Brevundimonas is a genus of Gram-negative bacteria widely distributed in nature and is also an opportunistic pathogen causing health care-associated infections. Brevundimonas strain 090558T was recovered from a blood culture of a cancer patient and was subjected to genome sequencing and analysis. The average nucleotide identity and in silico DNA-DNA hybridization values between 090558T and type strains of Brevundimonas species were 78.76% to 93.94% and 19.8% to 53.9%, respectively, below the cutoff to define bacterial species. Detailed phenotypic tests were performed, suggesting that 090558T can be differentiated from other Brevundimonas species by its ability to assimilate sodium acetate but not to utilize glucose, trypsin, or ß-glucosidase. Strain 090558T (GDMCC 1.1871T or KCTC 82165T) therefore represents a novel Brevundimonas species, for which the name Brevundimonas huaxiensis sp. nov. is proposed. All Brevundimonas genomes available in GenBank (accessed on 25 January 2021) were retrieved, discarding those labeled "excluded from RefSeq" by GenBank, and included 82 genomes for precise species curation. In addition to the 21 Brevundimonas species with genomes of type strains available, we identified 29 Brevundimonas taxa that either belong to the 12 Brevundimonas species without available genomes of type strains or represent novel species. We found that more than half (57.3%) of the 82 Brevundimonas genomes need to be corrected for species assignation, including species mislabeling of a type strain. Our analysis highlights the complexity of Brevundimonas taxonomy. We also found that only some Brevundimonas species are associated with human infections, and more studies are warranted to understand their pathogenicity and epidemiology. IMPORTANCEBrevundimonas is a genus of the family Caulobacteraceae and comprises 33 species. Brevundimonas can cause various infections but remains poorly studied. In this study, we reported a novel Brevundimonas species, Brevundimonas huaxiensis, based on genome and phenotype studies of strain 090558T recovered from human blood. We then examined the species assignations of all Brevundimonas genomes (n = 82) in GenBank and found that in addition to the known Brevundimonas species with genome sequences of type strains available, there are 29 Brevundimonas taxa based on genome analysis, which need to be further studied using phenotype-based methods to establish their species status. Our study significantly updates the taxonomy of Brevundimonas and enhances our understanding of this genus of clinical relevance. The findings also encourage future studies on the characterization of novel Brevundimonas species.

Pseudomonas defluvii sp. nov., isolated from hospital sewage.

A novel Gram-negative, obligate aerobic, mobile, rod-shaped and non-spore-forming bacterial strain, WCHP16T, was isolated from the wastewater treatment plant at West China Hospital in Chengdu, PR China. It was characterized using a polyphasic approach. Analysis of its 16S rRNA gene sequence showed that strain WCHP16T belonged to the genus Pseudomonas with the highest similarity to Pseudomonas qingdaonensis JJ3T (99.34 %), Pseudomonas shirazica VM14T (99.0 %), Pseudomonas plecoglossicida NBRC 103162T (99.0 %) and Pseudomonas asiatica RYU5T (99.0 %). Phylogenomic analysis based on 107 core gene sequences demonstrated that WCHP16T was a member of the Pseudomonas putida group but was distant from all closely related species. Whole-genome comparisons, using average nucleotide identity based on blast (ANIb) and in silico DNA-DNA hybridization (isDDH), confirmed low genome relatedness to all the known Pseudomonas species (below the recommended thresholds of 95 % [ANIb] and 70 % [isDDH] for species delineation). Phenotypic characterization tests showed that the utilization of phenylacetic acid and capric acid, but not d-arabitol, and inability to produce fluorescent (King B medium) in combination could distinguish this strain from other related species of the genus Pseudomonas. Therefore, based on genetic and phenotypic evidence, it is clear that strain WCHP16T represents a novel species, for which the name Pseudomonas defluvii sp. nov. is proposed. The type strain is WCHP16T (GDMCC1.1215T=CCTCC AB 2017103T=KCTC 52991T).

Leprosy in a low-incidence setting : Case report relevant to metagenomic next generation sequencing applications.

Leprosy is a disease caused by Mycobacterium leprae that results in disability. In 2000 the World Health Organization announced that leprosy had been eradicated. In nonendemic areas diagnosing leprosy is becoming a challenge for inexperienced clinicians. This case involves a male patient suffering from chronic numbness, hand deformity and recurrent erythema. Skin biopsy revealed granuloma and acid-fast staining of short-rod bacteria. Peripheral venous blood was subjected to metagenomic next generation sequencing and bioinformatics analysis, which revealed 3 unique sequence reads of M. leprae. Paraffin-embedded tissue and fresh samples scraped from skin lesions were subjected to in-house PCR targeting 16S rRNA, hsp65, rpoB, rpoT, ribF-rpsO, and mmaA. Sanger sequencing of amplicons from fresh samples and paraffin-embedded tissue verified the presence of M. leprae. For inexperienced clinicians in nonendemic areas nucleic acid amplification tests, such as in-house PCR, are helpful for diagnosing leprosy but sequence reads from metagenomic next generation sequencing may also provide evidence when interpreted cautiously.

[Pathogen Diagnosis of a Febrile HIV Case by the Metagenomic Next-generation Sequencing].

This study is aimed to explore the value of metagenomic next-generation sequencing (mNGS) in diagnosing pathogen in fever patients. It is often a challenge to identify the pathogen that caused the infection in the HIV patients with fever. How could the mNGS be helpful for pathogen diagnosis is unclear. Here we reported a case of human immunodeficiency virus (HIV) patient with 2-month period of fever. After routine clinical laboratory tests including the conventional smear, culture, serological tests and pathological examinations, the causal pathogen still remained undiagnosed. Then the lymph node biopsy tissue was subjected to broad-range polymerase chain reaction (PCR) and the peripheral blood was subjected to mNGS. At the same time, peripheral blood culture was carried out with an extension of culture time to acquire the pathogen. Results from both broad-range PCR and mNGS revealed the pathogen was Talaromyces marneffei. The isolate recovered from the peripheral blood culture was subjected to the whole-genome sequencing. Whole genome sequencing revealed that the antimicrobial resistance gene FLU1 existed in this pathogen's genome, but mNGS did not detect the FLU1 gene. Phylogenetic analysis based on whole genome sequence revealed that this isolate was far from other clones published in NCBI database. Here we reported a case of Talaromyces marneffei infection diagnosed by mNGS, showing that mNGS is helpful in etiological diagnosis for HIV patients with unexplained fever. However, application of mNGS in antimicrobial resistant genes detection and pathogen tracing need to be well-studied in the future.

First identification of an IMI-1 carbapenemase-producing colistin-resistant Enterobacter cloacae in China.

BACKGROUND: Carbapenem resistance among the Enterobacteriaceae is a serious healthcare challenge. bla IMI is a carbapenemase gene mediating resistance to carbapenems but has not been commonly found. A bla IMI-carrying Enterobacter cloacae, which was also resistant to colistin, is reported here. FINDINGS: E. cloacae strain WCHECl-1060 was recovered from a blood sample of a leukemia patient, who was not previously exposed to colistin. Strain WCHECl-1060 belongs to a new sequence type, ST410, and was resistant to carbapenems and colistin but was susceptible to third-generation cephalosporins. A new allelic variant of bla IMI-1, which has two silent mutations compared to the original bla IMI-1 variant, was found in strain WCHECl-1060. Conjugation and transformation experiments failed to transfer bla IMI-1, suggesting a likely chromosome origin. CONCLUSIONS: To our knowledge, this is the first report of an IMI-1 carbapenemase-producing colistin-resistant E. cloacae in China. Microbiological laboratories should be aware of the unusual carbapenem-resistant but third-generation cephalosporin-susceptible profiles of these IMI-producing isolates. The trend of colistin resistance among the Enterobacteriaceae should be also monitored.