OBJECTIVE To provide scientific and reasonable recommendations for the identification of Anaerobio-spirillum succiniciproducens in clinical microbiology laboratories by comparing the effectiveness of biochemical methods,matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF MS),and 16S rRNA gene sequencing.METHODS Methodological evaluation was conducted.A strain of A.succiniciprodu-cens was isolated on Mar.27,2023 from a patient with sepsis caused by a dog bite,who was admitted to Guang-dong Nongken Central Hospital,and analyzed for the morphological characteristics,culture methods,and colony features.The identification of the isolated strain was conducted by the automated microbial identification and anal-ysis system(VITEK 2 Compact 2,bioMerieux),MALDI-TOF MS including VITEK MS,MALDI Biotyper,Au-tof ms 1000,and EX-Accuspec,as well as 16S ribosomal RNA(rRNA)gene sequencing.The performance of each method was evaluated.RESULTSA.succiniciproducens was a strictly anaerobic gram-negative spiral bacteri-um,characterized by slow growth,flat and colorless transparent colonies,and negative oxidase and catalase activ-ity.When using VITEK 2 Compact ANC card,it was not successfully recognized;however,through the identifi-cation by VITEK MS,MALDI Biotyper,Autof ms 1000 and EX-Accuspec,it was all confirmed as A.succinicip-roducens.Additionally,16S rRNA gene sequencing technology also identified it as A.succiniciproducens.CONCLUSIONS Current automated biochemical identification systems are unable to accurately identify A.succi-niciproducens.MALDI-TOF MS and 16S rRNA gene sequencing techniques can reliably confirm A.succinicipro-ducens.Clinical microbiologists should select the appropriate identification method based on their available re-sources.

Objective:To identify and trace the origin of the Francisella tularensis subsp. novicida strain SJCS-979 isolated from the blood of a patient, so as to provide a reference for the traceability investigation of such infection events. Methods:Hot spring water samples that the patient had recently bathed in were collected to culture the causative agent, combined with the pathogenic characteristics and the patient′s activity before the bloodstream infection. The water samples were concentrated, acid-treated, and then the isolation of the causative agent was performed, following the method for Legionella detection in circulating cooling water. Suspected strains detected from the hot spring water were subjected to classical phenotypic identification, API ZYM and API NH strips tests, drug sensitivity testing, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identification, and the obtained data were compared with those of strain SJCS-979 isolated from the patient′s blood. A phylogenetic tree was constructed based on genomic analysis to determine the taxonomic status of strain SJCS-979 and related strains. Epidemiological data of Francisella tularensis subsp. novicida were collected and analyzed by integrating the global genetic and genomic data on GenBank database. Core single nucleotide polymorphism(SNP) comparisons were obtained using Snippy 3.2 software, and then an evolutionary tree was built to determine its population structure based on BAPS analysis. Results:Strain CC-2, isolated from the hot spring water, shared the same biochemical and drug sensitivity phenotype, and had a nearly consistent mass spectrometric profile with strain SJCS-979 isolated from the blood of a patient. Genomic phylogenetic tree analysis based on 120 core protein sequences showed that strains SJCS-979 and CC-2 fell on the same branch with known Francisella tularensis subsp. novicida strains. Bayesian genotyping showed that the global Francisella tularensis subsp. novicida strains with genomic data could be divided into six different sequence clusters. Strains SJCS-979 and CC-2 were located in the same taxonomic group with only 4 SNP differences, indicating that they might be the same clone. Conclusions:This study reports a case of bacteremia caused by Francisella tularensis subsp. novicida, and natural hot spring water may be the environmental source of this infection event.

OBJECTIVE To provide scientific and reasonable recommendations for the identification of Anaerobio-spirillum succiniciproducens in clinical microbiology laboratories by comparing the effectiveness of biochemical methods,matrix-assisted laser desorption ionization time-of-flight mass spectrometry(MALDI-TOF MS),and 16S rRNA gene sequencing.METHODS Methodological evaluation was conducted.A strain of A.succiniciprodu-cens was isolated on Mar.27,2023 from a patient with sepsis caused by a dog bite,who was admitted to Guang-dong Nongken Central Hospital,and analyzed for the morphological characteristics,culture methods,and colony features.The identification of the isolated strain was conducted by the automated microbial identification and anal-ysis system(VITEK 2 Compact 2,bioMerieux),MALDI-TOF MS including VITEK MS,MALDI Biotyper,Au-tof ms 1000,and EX-Accuspec,as well as 16S ribosomal RNA(rRNA)gene sequencing.The performance of each method was evaluated.RESULTSA.succiniciproducens was a strictly anaerobic gram-negative spiral bacteri-um,characterized by slow growth,flat and colorless transparent colonies,and negative oxidase and catalase activ-ity.When using VITEK 2 Compact ANC card,it was not successfully recognized;however,through the identifi-cation by VITEK MS,MALDI Biotyper,Autof ms 1000 and EX-Accuspec,it was all confirmed as A.succinicip-roducens.Additionally,16S rRNA gene sequencing technology also identified it as A.succiniciproducens.CONCLUSIONS Current automated biochemical identification systems are unable to accurately identify A.succi-niciproducens.MALDI-TOF MS and 16S rRNA gene sequencing techniques can reliably confirm A.succinicipro-ducens.Clinical microbiologists should select the appropriate identification method based on their available re-sources.

Objective:To identify and trace the origin of the Francisella tularensis subsp. novicida strain SJCS-979 isolated from the blood of a patient, so as to provide a reference for the traceability investigation of such infection events. Methods:Hot spring water samples that the patient had recently bathed in were collected to culture the causative agent, combined with the pathogenic characteristics and the patient′s activity before the bloodstream infection. The water samples were concentrated, acid-treated, and then the isolation of the causative agent was performed, following the method for Legionella detection in circulating cooling water. Suspected strains detected from the hot spring water were subjected to classical phenotypic identification, API ZYM and API NH strips tests, drug sensitivity testing, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) identification, and the obtained data were compared with those of strain SJCS-979 isolated from the patient′s blood. A phylogenetic tree was constructed based on genomic analysis to determine the taxonomic status of strain SJCS-979 and related strains. Epidemiological data of Francisella tularensis subsp. novicida were collected and analyzed by integrating the global genetic and genomic data on GenBank database. Core single nucleotide polymorphism(SNP) comparisons were obtained using Snippy 3.2 software, and then an evolutionary tree was built to determine its population structure based on BAPS analysis. Results:Strain CC-2, isolated from the hot spring water, shared the same biochemical and drug sensitivity phenotype, and had a nearly consistent mass spectrometric profile with strain SJCS-979 isolated from the blood of a patient. Genomic phylogenetic tree analysis based on 120 core protein sequences showed that strains SJCS-979 and CC-2 fell on the same branch with known Francisella tularensis subsp. novicida strains. Bayesian genotyping showed that the global Francisella tularensis subsp. novicida strains with genomic data could be divided into six different sequence clusters. Strains SJCS-979 and CC-2 were located in the same taxonomic group with only 4 SNP differences, indicating that they might be the same clone. Conclusions:This study reports a case of bacteremia caused by Francisella tularensis subsp. novicida, and natural hot spring water may be the environmental source of this infection event.

Objective:To analyze the morphology and molecular biology and clarify the taxonomic status of one Cupriavidus species strain SZY C1 isolated from clinical wound specimens. Methods:Strain SZY C1 was subjected to physiological and biochemical identification, 16S rRNA gene sequencing, and whole genome sequencing. Its genomic features and virulence genes were analyzed using bioinformatics software.Results:Strain SZY C1 was a gram-negative, non-fermenting bacterium wihout flagella and the ability to form spores. After culturing on Columbia blood agar plates for 24 h, it formed grayish-white colonies that were round, raised, opaque, and had neatly defined margins. Based on 16S rRNA gene sequence analysis, strain SZY C1 belonged to the genus Cupriavidus with the highest 98.52% similarity to Cupriavidus metallicuns. The genome size of strain SZY C1 was determined to be 5 515 517 bp, with a G+ C content of 67.87%. Whole genome sequencing showed that strain SZY C1 had the closest phylogenetic relationship with Cupriavidus agavae, with an average nucleotide identity value of 84.76% and a digital DNA-DNA hybridization value of 29.1%, which were lower than the identification threshold for prokaryotic species. The strain SZY C1 carried multiple virulence genes, drug resistance genes, and heavy metal resistance genes. Conclusions:Based on phenotypic and genomic analyses, the strain SZY C1 is a potential new species of the Cupriavidus genus.

Objective:To analyze the biological characteristics, phylogeny and the taxonomic status of strain 7712 (=CGMCC 1.17031=NBRC 113783=KCTC 15766) isolated from a clinical blood sample.Methods:Strain 7712 was identified by the cultural properties, cellular and colonial morphology, physiological and biochemical reactions, matrix-assisted laser desorption ionization time-of-flight mass spectrometry system, and genome correlation index analysis. The genomic phylogenetic tree was construct to analyze the taxonomic position. The virulence factors and resistance genes of strain 7712 and related strains were then compared by the online virulence factor database and online comprehensive antibiotic research database respectively.Results:Strain 7712 was urease negative, gram-negative nonfermenters, which was identified as Ochrobactrum anthropi by VITEK GN card. The 16S rRNA gene analysis showed that the strain was closely related to the members of genera Ochrobactrum and Brucella. The phylogenetic tree showed that strain 7712 was clustered together with Ochrobactrum teleogrylli LCB8 T and Ochrobactrum haematophilum CCUG 38531 T, along with genus Brucella and other Ochrobactrum species. The genome relatedness indexes analysis showed that the average nucleotide identity between strain 7712 and Ochrobactrum teleogrylli LCB8 T was 98.16%, which was higher than the threshold for prokaryotic species. Genetic prediction showed that strain 7712 carried several virulence-related genes and resistance-related genes, of which the existence of OCH gene might be responsible to the resistance to cephalosporin. Conclusions:A case of human infection caused by Ochrobactrum teleogrylli is identified, which would help promote the understanding of biodiversity of genus Ochrobactrum.

AIM:This study aims to investigate the utility of the Christie-Atkinson-Munch-Peterson(CAMP)test in identifying Streptococcus agalactiae and to assess the sensitivity of positive CAMP test results for this identification.We also identified and analyzed Streptococcus agalactiae isolates that exhibited negative CAMP test results and conducted a preliminary study on the possible mechanisms behind these occurrences.METHODS:Streptococcus agalactiae isolates were collected from the University Town Branch of Guangdong Provincial Hospital of Traditional Chinese Medicine be-tween January 2018 and January 2023.Isolates identified as Streptococcus agalactiae using an automated rapid microbial mass spectrometry detection system underwent the CAMP test.CAMP-negative strains were screened,and the presence of the cfb gene was assessed.We also conducted a statistical analysis of the clinical sources of the samples and the drug sensi-tivity test results for Streptococcus agalactiae.RESULTS:Among 112 Streptococcus agalactiae strains,two CAMP-nega-tive strains were identified,which were confirmed as Streptococcus agalactiae through 16S rDNA sequencing and showed negative detection of the cfb gene.The clinical sample sources for the 112 strains were as follows:midstream urine(34.82%),semen(34.82%),cervical swab(8.04%),secretion(4.46%),urethral swab(4.46%),venous blood(3.57%),pus(3.57%),sputum(1.79%),wound swab(1.79%),and unknown sources(1.79%).All Streptococcus agalactiae strains in our laboratory were found to be 100%sensitive to penicillin,linezolid,ampicillin,and vancomycin,while the resistance rate to levofloxacin was 24.44%.CONCLUSION:The positive results of the CAMP test demonstrate its potential for identifying Streptococcus agalactiae.The negative CAMP test results observed in the two strains could be at-tributed to the deletion of the cfb gene.The majority of Streptococcus agalactiae detected in clinical laboratory work were sourced from midstream urine and semen,indicating a potential association with urinary tract infections.However,the correlation with male reproductive diseases remains uncertain.

AIM:This study aims to investigate the utility of the Christie-Atkinson-Munch-Peterson(CAMP)test in identifying Streptococcus agalactiae and to assess the sensitivity of positive CAMP test results for this identification.We also identified and analyzed Streptococcus agalactiae isolates that exhibited negative CAMP test results and conducted a preliminary study on the possible mechanisms behind these occurrences.METHODS:Streptococcus agalactiae isolates were collected from the University Town Branch of Guangdong Provincial Hospital of Traditional Chinese Medicine be-tween January 2018 and January 2023.Isolates identified as Streptococcus agalactiae using an automated rapid microbial mass spectrometry detection system underwent the CAMP test.CAMP-negative strains were screened,and the presence of the cfb gene was assessed.We also conducted a statistical analysis of the clinical sources of the samples and the drug sensi-tivity test results for Streptococcus agalactiae.RESULTS:Among 112 Streptococcus agalactiae strains,two CAMP-nega-tive strains were identified,which were confirmed as Streptococcus agalactiae through 16S rDNA sequencing and showed negative detection of the cfb gene.The clinical sample sources for the 112 strains were as follows:midstream urine(34.82%),semen(34.82%),cervical swab(8.04%),secretion(4.46%),urethral swab(4.46%),venous blood(3.57%),pus(3.57%),sputum(1.79%),wound swab(1.79%),and unknown sources(1.79%).All Streptococcus agalactiae strains in our laboratory were found to be 100%sensitive to penicillin,linezolid,ampicillin,and vancomycin,while the resistance rate to levofloxacin was 24.44%.CONCLUSION:The positive results of the CAMP test demonstrate its potential for identifying Streptococcus agalactiae.The negative CAMP test results observed in the two strains could be at-tributed to the deletion of the cfb gene.The majority of Streptococcus agalactiae detected in clinical laboratory work were sourced from midstream urine and semen,indicating a potential association with urinary tract infections.However,the correlation with male reproductive diseases remains uncertain.

Objective:To identify and characterize one Spiroplasma strain (designated as DGKH1) isolated from the blood of a patient with sepsis. Methods:The traditional bacterial culture, staining, morphological observation, physiological and biochemical identification, 16S rRNA gene sequencing, phylogenetic analysis, genome sequencing, and the genome-related index analysis were performed to accurately determine the taxonomic status of the strain DGKH1. Antibiotic susceptibility testing was performed using a specific kit for culturing and testing Ureaplasma urealyticum/ Metamycoplasma hominis. Results:The strain DGKH1 could weakly grow on Columbia blood agar, chocolate agar, and Haemophilus chocolate 2 agar. However, it did not grow in liquid culture medium containing tetracycline (4 μg/ml), doxycycline (1 μg/ml), minocycline (1 μg/ml), josamycin (2 μg/ml), roxithromycin (1 μg/ml), clarithromycin (1 μg/ml), or telithromycin (1 μg/ml). DGKH1 resembling Metamycoplasma hominis formed "fried egg-like colonies" on Mycoplasma solid culture medium. DGKH1 could not be stained by Gram staining. When observed under transmission electron microscopy (TEM) using phosphate buffer as the matrix, the bacteria were spiral-shaped. Results of 16S rRNA gene sequence alignment showed that DGKH1 was highly similar (99.85%) to Spiroplasma eriocheiris CCTCC M 207170 T. However, the urea decomposition test was positive, which was different from all of the known Spiroplasma species. The phylogenetic analysis based on whole genome showed that DGKH1 was clustered in a small branch along with Spiroplasma eriocheiris CCTCC M 207170 T. However, the average nucleotide identity (ANI) and digital DNA-DNA hybridization (dDDH) values between the two strains were 94.14% and 56.00%, respectively, both below the threshold for prokaryotic species identification. Conclusions:DGKH1 represented a potential new species of genus Spiroplasma, closely related to Spiroplasma eriocheiris. Some microbiological characteristics of DGKH1 were similar to Mycoplasmas. However, the natural host and epidemiological data of DGKH1 need to be further studied.

Objective:To analyze the molecular epidemiological characteristics of Campylobacter fetus subsp. testudinum ( Cft). Methods:Fifteen strains of Cft collected in our laboratory from 2010 to 2022 were subjected to whole-genome sequencing. Their epidemiological characteristics were analyzed based on the global genome data of Cft on GenBank database. MLST-GrapeTree software was used to obtain the genetic structure of Cft strains. A phylogenetic tree was constructed using core-genome single nucleotide polymorphism (cgSNP) analysis, and the sequence clusters were identified using rhierBAPS. Virulence genes and drug resistance genes of Cft strains were annotated using CARD, ResFinder and VFDB database. Their susceptibility to antibiotics was tested using E-test method and the results were analyzed using the CLSI-M45 sensitivity standard for Campylobacter jejuni/ Campylobacter coli. Results:Based on average nucleotide identity (ANI) analysis, the genome data of 41 Cft strains including 24 isolated from human, 13 from animals and four of unknown sources were collected from GenBank database. Among the 24 human-derived strains, 20 were linked to Asian descent and only one was linked to Caucasian descent (spouse of Asian descent), showing statistically significant differences in human ethnicity. All of the 13 animal-derived strains were originated from reptilian sources, including six from turtles, four from snakes and three from lizards. MLST revealed that ST46 was the predominant ST in China, while ST15 was the major sequence type in the United States. Grapetree analysis also demonstrated that the genetic diversity in China was greater than that in the United States. The phylogenetic tree constructed based on cgSNP and BAPS identified six distinct sequence clusters. The Chinese isolates were scattered in diverse sequence clusters and closely related to animal-derived strains, while the American isolates mainly belonged to ST15. The genes encoding virulence factors such as flagella, glycosylation systems and adhesins were carried by all of the 41 Cft strains (100.00%). The invasion-related virulence genes, such as the genes encoding the IV type secretion system ( virB4, virB9, virD4) and the resistance-related tetO efflux pump gene were specifically identified in the emerging ST74 clones. In vitro drug susceptibility testing of 15 Chinese isolates revealed 46.67% of the Cft strains were resistant to ciprofloxacin and 100.00% were sensitive to erythromycin. Conclusions:The global sequence clusters of Cft isolates showed a great genetic diversity. Most of the people with Cft infection had basic immune diseases and might have eaten or had contact with reptiles. Notably, the Chinese domestic infection of ST46 and the emerging ST74 should arouse our more attention.