Serotype distribution and antimicrobial resistance of pediatric Streptococcus pneumoniae isolated from inpatients and outpatients at Beijing Children's Hospital

Abstract Background Understanding the epidemiology of Streptococcus pneumoniae (S. pneumoniae) isolates is important for pneumonia treatment and prevention. This research aimed to explore the epidemiological characteristics of S. pneumoniae isolated from pediatric inpatients and outpatients during the same period. Methods S. pneumoniae were isolated from unsterile samples of inpatients and outpatients younger than five years old between March 2013 and February 2014. The serotypes were determined using diagnostic pneumococcal antisera. The resistance of each strain to 13 antibiotics was tested using either the E-test or the disc diffusion method. The Sequence Types (STs) were analyzed via Multilocus Sequence Typing (MLST). Results The dominant serotypes obtained from inpatients were 19F (32.9 %), 19A (20.7 %), 23F (10.7 %), 6A (10.0 %), and 14 (8.6 %), while those from outpatients were 19F (13.6 %), 23F (12.9 %), 6A (10.0 %), 6B (10.0 %), and 19A (7.9 %). The coverage rates of 13-valent Pneumococcal Conjugate Vaccine (PCV) formulations were high in both groups. The nonsusceptibility to penicillin, cefuroxime, imipenem, erythromycin, and trimethoprim-sulfamethoxazole among the inpatient isolates was 7.1 %, 92.8 %, 65.7 %, 100 %, and 85.0 %, respectively, while that among the outpatient isolates was 0.7 %, 50.0 %, 38.6 %, 96.4 %, and 65.7 %, respectively. There were 45 and 81 STs detected from the pneumococci isolated from inpatients and outpatients, respectively. CC271 was common among both inpatients and outpatients (43.6 % and 14.3 %). Conclusions Pneumococcal vaccine-related serotypes are prevalent among both inpatients and outpatients, especially among inpatients, who exhibit more severe antibiotic resistance. Therefore, universal immunization with PCV13 would decrease the hospitalization rate due to S. pneumoniae and the antibiotic resistance rate of S. pneumoniae.

Antimicrobial resistance and genomic characteristics of Salmonella enterica serovar Derby isolates from clinical patients and food sources in Hangzhou / 中华微生物学和免疫学杂志

Objective:To analyze the antimicrobial resistance and genomic characteristics of Salmonella enterica serovar Derby strains isolated from human and food sources in Hangzhou. Methods:A total of 60 Salmonella enterica serovar Derby strains isolated in Hangzhou during the period from 2015 to 2020 were subjected to antimicrobial susceptibility testing, pulsed field gel electrophoresis (PFGE) typing and whole-genome sequencing. Multilocus sequence typing (MLST), core genome multilocus sequence typing (cgMLST) and the identification of antimicrobial resistance genes were performed using the sequencing data. Phylogenetic tree based on the single nucleotide polymorphism (SNP) sites in the 60 genomes from Hangzhou and 379 genomes from public databases was constructed. Results:No significant difference was observed in the drug resistance rates between the clinical strains and food strains in Hangzhou. The multidrug resistance (MDR) rate was 76.7% (46/60). All of the 60 Salmonella Derby strains were positive for the antimicrobial resistance genes aac(6′)- Iaa and fosA7. The 60 strains were subtyped into 46 molecular types by PFGE and 53 molecular types by cgMLST(HC2). Except for one strain belonging to ST3220, the other Salmonella Derby strains were ST40. The phylogenetic analysis showed that some strains isolated in Hangzhou were close to the strains in Southeast Asia, suggesting the possibility of cross-border transmission of ST40 strains, with the main food sources being pork and fish; other strains were close to those circulating in Beijing, Guangzhou, Hubei, Chongqing and other provinces, suggesting the possibility of cross-province transmission of the strains, with the main food sources being pork, beef and chicken. Conclusions:The epidemic of Salmonella Derby in Hangzhou was mainly caused by the spread of ST40 strains and MDR was common. Clinical infections might be closely related to the consumption of pork, beef, chicken and fish. There was the possibility of cross-border transmission of Salmonella Derby between Hangzhou and Southeast Asia and cross-province transmission in China.

Genetic variation characteristics of HA gene of influenza A virus (H3N2) in Guizhou province from 2017 to 2019 / 中国基层医药

Objective:To analyze the genetic variation characteristics of the HA gene of influenza A virus (H3N2) in Guizhou province from 2017 to 2019. Methods:Twenty strains of influenza A virus (H3N2) were randomly selected from 10 network laboratories in Guizhou province for RNA extraction. Reverse transcriptase-polymerase chain reaction and sequencing were performed. The products were analyzed using bioinformatics software.Results:The nucleotide homology of the HA gene of the 20 strains was 97.7%-100%, which was highly homologous to the vaccine strains A/Hong-Kong/4801/2014 recommended by WHO in 2017 and A/Singapore-INFIMH/16-0019/2016 recommended by WHO in 2018, but they were significantly different from the vaccine strain A/Kansas/14/2017 recommended by WHO in 2019. Genetic analysis showed that the 20 strains were divided into two branches, and the strains that were prevalent in 2019 were located in different branches, with marked genetic differences. Key site analysis showed mutations in antigenic determinants A, B, C, and E and mutations in the anterior and posterior walls of receptor binding sites. Key site analysis also showed that there was an increase in the number of glycosylation sites compared with the vaccine strains prevalent in the same year. Genetic distance, antigen sites, and glycosylation sites were slightly different between virus strains prevalent in 2017-2018 and virus strains prevalent in 2019. Conclusion:The HA gene of the influenza A virus subtype H3N2 in Guizhou province from 2017 to 2019 showed heterogeneity and gene mutation, especially in 2019. Therefore, close monitoring of the genetic evolution of the influenza A virus subtype H3N2 is necessary.

Genetic characteristics of multi-locus sequence typing of Brucella isolates in Guizhou Province from 2017 to 2021 / 中华地方病学杂志

Objective:To study the multi-locus sequence typing (MLST) gene characteristics of Brucella isolates in Guizhou Province. Methods:Brucella strains, which were isolated from 2017 to 2021 in Guizhou Province (preserved in the Bacterial and Viral Seed Bank of Guizhou Center for Disease Control and Prevention) were identified Brucella and species/types by BCSP31-PCR and AMOS-PCR methods, respectively. MLST method was used for genotyping, and Biometrics 8.0 software was used for cluster analysis of the typing results. Results:A total of 32 strains of Brucella were isolated in Guizhou Province and identified as Brucella melitensis ( B.melitensis) by BCSP31-PCR and AMOS-PCR methods. These strains were classified into 2 ST types (ST8 and ST39) by MLST method, with 28 strains of ST8 type(87.5%) and 4 strains of ST39 type (12.5%). The 28 strains of ST8 type were distributed in 7 cities (prefectures) of Guizhou Province, while the 4 strains of ST39 type were only found in Qianxinan Buyi and Miao Autonomous Prefecture. The cluster analysis results showed that ST8 and ST39 types strains were clustered in a group with the reference strain of B.melitensis, and there was only one nucleotide site difference between ST39 and ST8 types in the glk gene, indicating a close genetic relationship. Conclusions:B.melitensis is the main pathogen of the brucellosis epidemic in Guizhou Province in recent years. ST8 is the dominant MLST genotype in Guizhou Province.

Multi-locus sequence typing of human Brucella isolated in Sichuan Province from 2014 to 2020 / 中华地方病学杂志

Objective:To learn about the genotyping of human Brucella isolated from Sichuan Province. Methods:BCSP31-PCR and AMOS-PCR were used to identify the genus and biotype of the 66 strains isolated from confirmed human brucellosis cases in Sichuan Province from 2014 to 2020, respectively. The isolated strains were genotyped by multi-locus sequence typing (MLST)-9. The sequence type (ST) was compared trough the online MLST database. A minimum spanning tree (MST) was constructed to cluster the newly discovered and known ST using the BioNumerics software version 7.6.Results:The 66 strains isolated from human cases of brucellosis in Sichuan Province from 2014 to 2020 were Brucella, and 65 of them were Brucella melitensis while one strain was Brucella abortus. The MLST method identified three known STs (ST-8, ST-39 and ST-2) and one newly type (ST-101). Among them, ST-8 was the main ST in Sichuan Province (90.91%, 60/66), another 4 strains of Brucella melitensis were ST-39, and 1 strain of Brucella abortus was ST-2. The newly type ST-101 was isolated from Leshan City in 2019, belonging to the Brucella melitensis and closely related to the evolution of ST-8. Conclusion:Brucella melitensis is the main epidemic Brucella strain in Sichuan Province, ST-8 is predominant genotype, with a small amount of ST-39, ST-101 and ST-2.

Multilocus sequence typing, clinical characteristic, and drug resistance of Salmonella typhimurium in 93 children / 中华实用儿科临床杂志

Objective:To investigate the multilocus sequence typing (MLST), clinical manifestations, and drug resistance of Salmonella typhimurium in children, thus providing references for the diagnosis, treatment, and prevention of pediatric Salmonella typhimurium infection.Methods:The clinical data of patients with Salmonella typhimurium serotypes confirmed by stool or blood culture between November 2017 and October 2020 were retrospectively collected from Fujian Maternity and Child Health Hospital.MSLT and drug susceptibility test were performed on Salmonella typhimurium isolated from the samples. Kruskal- Wallis test, Chi- square test, and Fisher′ s exact probability method were employed for data analyses. Results:Salmonella typhimurium was cultured from clinical samples of 96 children, of which, 93 samples were effective, including 92 stool samples and 1 blood sample from 53 boys(56.99%) and 40 girls(43.01%). The median age of disease onset occurred at 12.0 (8.5-22.0) months, with peak months of onset ranging from July to October.According to MLST classification, 93 children were divided into ST34 classification( n=58), ST19 classification( n=22) and other classification( n=13). Respiratory symptoms were significant different among MLST classification, and ST34 type Salmonella typhimurium enteritis was more commonly accompanied by respiratory symptoms ( χ2=17.657, P<0.001; Cramer V=0.421, P<0.001). There were significant differences in the drug sensitivity to Ampicillin ( χ2=8.774, P=0.033), Piperacillin tazobactam ( χ2=6.713, P=0.022), Ciprofloxacin ( χ2=20.780, P<0.001), Sulfamethoxazole ( χ2=15.364, P=0.001), Ampicillin sulbactam ( χ2=17.626, P=0.001) and Levofloxacin ( χ2=25.648, P<0.001) among 3 groups.No significant difference was found in the sensitivity to Ceftriaxone ( χ2=1.027, P=0.621), Ceftazidime ( χ2=7.637, P=0.059), Cefepime ( χ2=6.099, P=0.116) and Cefoperazone/Sulbactam ( χ2=2.405, P=0.649). All MLST types were sensitive to Imipenem and Meropenem. Conclusions:Salmonella typhimurium infection mainly affects infants, with the peak months of onset ranging from July to October.MLST34 is the main serotype, accompanied respiratory symptoms.Antibiotics should be selected according to drug sensitivity, and third-generation cephalosporins can be selected empirically without drug susceptibility test results.

Inhibitory and clearance effect of azithromycin combined with levofloxacin on biofilm of different ST types of Klebsiella pneumoniae / 中国临床药理学与治疗学

AIM: Given the biofilm formation abili- ty of different ST-type Klebsiella pneumoniae, our study was aimed at exploring the inhibitory and clearance of azithromycin combined with levofloxacin on the biofilm of Klebsiella pneumoniae of different ST-types and providing a new strategy for the prevention of biofilm formation in the treatment of post-infectious Klebsiella pneumoniae. METHODS: 9 strains of Klebsiella pneumoniae from all susceptibility groups, 19 strains of Klebsiella pneumoniae producing extended-spectrum β - lactamases (ESBLs), and 37 strains of Carbapenem-resistant Klebsiella pneumoniae (CRKP) were randomly collected from the samples of patients hospitalized in the First Affiliated Hospital of Wannan Medical College from August 2019 to November 2021. The isolates were identified using VITEK MS IVD KB V3.2 and VITEK 2-Compact 60. Multilocus sequence typing (MLST) was performed to analyze the homology of each strain; crystal violet staining was used for semi -quantitative detection of biofilm to compare the differences in biofilm formation ability between different ST-type Klebsiella pneumoniae. Different ST-type strains were selected, and the partial inhibitory concentration index (FICI) was calculated by micro broth dilution method to judge the combination effect and select the optimal combination concentration; crystalline violet staining method was used to investigate the inhibition and clearance effect of azithromycin combined with levofloxacin on the biofilm of different ST-type Klebsiella pneumoniae; laser scanning confocal fluorescence microscopy was used to observe the structural changes of the biofilm of Klebsiella pneumoniae before and after the effect of the antibacterial drugs. RESULTS: MLST typing results showed that the sensitive group of Klebsiella pneumoniae strains had 8 sequences such as ST86, ST727, etc., the ESBLs group strains belonged to 14 sequence types such as ST15, ST37, ST11, etc., of which ST15 accounted for 26.32% (5 / 19). The CRKP group strains belonged to 9 sequence types such as ST11, ST15, ST656, etc., of which ST11 accounted for 48.65% (18/37), ST15 accounted for 27.03% (10/37); ST15 (ESBLs), ST11 (CRKP), ST15 (CRKP) type Klebsiella pneumoniae biofilms all reached maturity on the 5th day, the ST15 (ESBLs) group had a stronger ability to produce material to be membranous than the ST15 (CRKP) group. The ST11 (CRKP) group had a stronger ability to produce material to be membranous than the ST15 (CRKP) group (Pazithromycin>levofloxacin, and the highest clearance rate was 44.79%. CONCLUSION: There are differences in biofilm formation ability between different ST-type Klebsiella pneumoniae, and azithromycin combined with levofloxacin has a better inhibitory effect on different ST-type Klebsiella pneumoniae biofilm, conbined application can be used in the treatment of biofilm infections early stage.

Investigation of a suspected outbreak of carbapenem-resistant Klebsiella pneumonia infection / 上海预防医学

ObjectiveTo investigate a suspected outbreak of healthcare-associated infection （HAI） caused by carbapenem-resistant Klebsiella pneumonia （CRKP） in a secondary grade-A hospital， analyze the infection source and transmission route， and put forward corresponding preventive and control measures. MethodsEpidemiological investigation was conducted on 5 patients with CRKP infection in department of neurosurgery during December 23‒30， 2021. Specimens were collected with the environmental microbiology monitoring procedure. CRKP isolated from the environmental samples were analyzed by multilocus sequence typing （MLST） method. Comprehensive measures were taken to control the CRKP infection. ResultsThe 5 infected patients were located in 3 rooms， and all were diagnosed as HAI. The antimicrobial susceptibility testing results from the specimens of 3 CRKP infected patients were the same. Through environmental microbiology monitoring， CRKP strains were detected from the faucet handle and sink specimens in 3 rooms. The results of MLST analysis showed that the faucet handle and sink specimens in room 2 and 3 were ST11 type. The environmental specimen in room 1 was ST23 type. The suspected outbreak was effectively controlled after comprehensive interventions. ConclusionHAI suspected outbreak might be caused by the environmental contamination from the pathogens of CRKP-infected patients as well as the contaminated hands of medical staff and accompanying family members. Strengthening the publicity， education and management of medical staff and accompanying staff， early identification of infection outbreaks， and timely comprehensive control measures are the keys to controlling multidrug-resistant nosocomial infection outbreaks.

Genetic and evolutionary characteristics of clindamycin-resistant Staphylococcus aureus in Yangzhou / 公共卫生与预防医学

Objective To investigate the drug resistance phenotype, drug resistance genes and molecular characteristics of clinical isolates of Staphylococcus aureus in Yangzhou from 2016 to 2020. Methods A total of 71 strains of clindamycin resistant Staphylococcus aureus were collected. Molecular typing of the strains was performed using multilocus sequence typing (MLST) and SNP. Antimicrobial minimal inhibitory concentrations were detected by the method of microdilution broth. Different resistance genes were detected. Results A total of 71 strains of clindamycin resistant Staphylococcus aureus were collected in this study, of which 42 strains (59.15%) were inherently resistant and 29 strains (40.85%) were induced resistant ; 44 strains (61.97%) were found to be methicillin resistant Staphylococcus aureus (MRSA). Among the 71 strains , 18 ST types were found , and the detection rates of mecA and ermB in ST59 strain were higher than those in other ST types. Among the clustered strains, CC59 was inherently resistant. Conclusion The clinically isolated Staphylococcus aureus in Yangzhou has severe drug resistance, especially the resistance to clindamycin. CC59 clone group carries many drug resistance genes, and all of them are MRSA . This study provides reliable data for clinical selection of appropriate drugs and further investigation of the prevalence of clindamycin-resistant strains.

Antimicrobial resistance in and multilocus sequence typing of Campylobacter jejuni in meat and meat products / 预防医学

Objective@#To investigate the antimicrobial resistance in and multilocus sequence typing (MLST) of Campylobacter jejuni in meat and meat products in Liaoning Province, so as to provide insights into the management of C. jejuni infection. @*Methods@#Nine C. jejuni isolates from meat and meat products in 2020 were subjected to whole genome sequencing, and the minimum inhibitory concentration was measured with the agar dilution method. MLST of C. jejuni isolates was performed with the microbial resistance mechanism traceability reference database and analysis system.@*Results@#Six drug-resistant C. jejuni isolates were detected, and there were four multidrug-resistant isolates. There were six C. jejuni isolates resistant to tetracycline, five isolates resistant to nalidixic acid, four isolates resistant to ciprofloxacin, two isolates resistant to florfenicol, one isolate resistant to gentamicin and one isolate resistant to streptomycin. Nine C. jejuni isolates showed sensitive to azithromycin, chloramphenicol and clindamycin. MLST identified six ST types in nine C. jejuni isolates, with ST45 and ST2274 as the predominant type, and detected one isolate with unclassified ST type. Phylogenetic analysis showed that KW028 and KW029 of ST45 type were closely related and had high homology, and KW040 and KW042 of ST2274 type were closely related with high homology, while KW007 of ST6701 type was closely related to KW040 and KW042 of ST2274 type, with only one pgm housekeeper gene in difference. @*Conclusions@#High resistance to tetracycline, nalidixic acid and ciprofloxacin was detected in nine C. jejuni isolates from meat and meat products, and ST45 and ST2274 were predominant ST types of C. jejuni.

Clinical and epidemiological features analysis of pneumocystis jirovecii pneumonia in kidney transplant recipients / 器官移植

Objective To investigate clinical and epidemiological features of pneumocystis jirovecii pneumonia (PJP) in kidney transplant recipients. Methods Clinical data of 68 kidney transplant recipients admitted from July, 2021 to December, 2021 were collected. All patients were divided into the PJP group (n=11), common pulmonary infection group (n=24) and non-pneumonia group (n=33) according to the status of pulmonary infection. The incidence and treatment of PJP after kidney transplantation were analyzed. Basic characteristics and laboratory parameters of the recipients were compared among all groups. The genotyping and transmission map of PJP patients were evaluated. Results Among 64 kidney transplant recipients, 11 cases were definitely diagnosed with PJP. The most common clinical manifestations included elevated body temperature, and dry cough complicated with progressive dyspnea. Chest CT scan showed diffuse interstitial inflammation and ground glass-like lesions of bilateral lungs in all patients. After diagnosis, all patients were orally given with compound sulfamethoxazole for 3-4 weeks. Two patients received non-invasive ventilator-assisted ventilation due to severe lung infection and dyspnea, and the remaining patients were given with nasal cannula oxygenation. One patient experienced elevated serum creatinine level upon discharge, and developed renal allograft failure. The remaining 10 recipients with PJP obtained normal renal allograft function, and no recipient died. Compared with the non-pneumonia group, the rejection rate was higher, the length of hospital stay was longer, the lymphocyte count was less, the lymphocyte proportion was lower, the levels of C-reactive protein, serum creatinine and lactate dehydrogenase were higher, and the levels of serum albumin was lower and CD4+T cell count was less in the PJP group (all P < 0.05). Compared with common pulmonary infection group, the lymphocyte count was less, the lymphocyte proportion was lower, the CD4+T cell count was less and 1, 3-β-D- glucan (BDG) level was higher in the PJP group (all P < 0.05). No new genotype was detected in 10 of the 12 testing samples. It was considered that PJP mainly depended on two transmission chains and two independent transmission individuals. Conclusions Kidney transplant recipients are prone to pneumocystis jirovecii (PJ) infection due to impaired cellular immune function. The most common clinical manifestations consist of elevated body temperature and dry cough complicated with progressive dyspnea, accompanied by headache and fatigue in partial patients. Chest CT scan shows diffuse interstitial inflammation and ground glass-like lesion of bilateral lungs. PJ may be transmitted through respiratory tract. Small-scale PJP might occur in the follow-up outpatient of kidney transplant recipients. Preventive measures should be delivered in a timely manner.

Molecular characteristics of Streptococcus suis type 2 from humans in Zhejiang Province / 中华传染病杂志

Objective:To determine the molecular characteristics of Streptococcus suis type 2 (SS2) in Zhejiang Province. Methods:Twenty-nine SS2 sporadic human isolates in Zhejiang Province from Januery 2005 to July 2021 were genotyped by pulsed-field gel electrophoresis (PFGE), multilocus sequence typing (MLST), and minimum core genome (MCG) sequence typing.Results:Among 29 strains, 10 PFGE patterns and three main clusters were obtained by PFGE. Twenty-one (72.41%) of the strains were divided into two main branch groups and the remaining eight (27.59%) showed genetic diversity with the similarity ranging from 49.7% to 94.7%. Three sequence types were obtained from 29 strains by MLST, including ST7 (86.21%(25/29)), ST1 (10.34%(3/29)) and ST25 (3.45%(1/29)). In addition, three genotypes were obtained from 29 strains by MCG, including genotype E (41.38%(12/29)), genotype group 1 (55.17%(16/29)) and genotype group 4 (3.45%(1/29)).Conclusions:Two large clonal groups of highly pathogenic strains of SS2 have been prevalent in Zhejiang Province. A few strains display genetic diversity, indicating genetic variation may exist during transmission.

Clinical characteristics and gene analysis of one case of glycogen storage disease type Ⅱ / 中国基层医药

Objective:To investigate the key points of diagnosis and treatment of glycogen storage disease type Ⅱ(GSD Ⅱ).Methods:The clinical data of one child patient with GSD Ⅱ who received treatment in Hainan Children's Hospital on May 7, 2017 were retrospectively analyzed.Results:The child presented with atypical clinical manifestations, including pneumonia first, accompanied by muscle weakness and elevated muscle enzymes. Whole-genome sequencing showed that there were two heterozygous mutations in the acid alpha-glucosidase (GAA) gene, c.871C > T and c.1447G > A. The child was diagnosed with GSD Ⅱ.Conclusion:GSD Ⅱ has atypical clinical manifestations. It is easily misdiagnosed. Early whole-genome sequencing is helpful for the diagnosis of GSD Ⅱ.

Multilocus sequence typing of Streptococcus pyogenes isolated from children in Shenzhen / 中华实用儿科临床杂志

Objective:To explore the epidemiological characteristics of Streptococcus pyogenes, namely β-hemolytic Group A Streptococcus (GAS) in children in Shenzhen. Methods:Multilocus sequence typing (MLST) data on the epidemic clonal population of GAS infection in children in Shenzhen Children′s Hospital from January 2016 to December 2018 were retrospectively analyzed.In the present study, 32 GAS strains belonging to 7 different emm types were from 32 children′s with impetigo, cellulitis, scarlet fever, sepsis, pneumonia, obstructive sleep apnea hypopnea syndrome, bronchitis, allergy with rhinitis, buttock abscess, allergic purpura or pharyngeal tonsillitis, which were isolated from 23 throat swabs, 5 sputum samples, 3 pus and 1 blood.Using polymerase chain reaction technology, 7 pairs of allelic housekeeping genes ( gki, gtr, murI, mutS, recP, xpt and yqiL) of 32 GAS isolates were analyzed, and the target gene products were subjected to sequencing.Then the obtained gene sequences of each allele were submitted to the MLST database to obtain the allele profile.Finally, the allele profiles were introduced in the MLST database again to confirm the sequence typing (ST). Results:The GAS clone groups of emm 1.00 and its subtypes, emm 4.00, emm 12.00 and its subtypes, emm 22.00, emm 28.00, emm 75.00, and emm 89.00 belonged to the sequence typing ST28, ST39, ST36, ST46, ST52, ST49, and ST921, respectively. Conclusions:From 2016 to 2018, the MLST clone populations of GAS isolates causing infections in children in Shenzhen are classified as ST28, ST39, ST36, ST46, ST52, ST49 and ST921.

Association of clustered regularly interspaced short palindromic repeats with genotyping and drug-resistance genes of group B Streptococcus / 中华围产医学杂志

Objective:To investigate the distribution of clustered regularly interspaced short palindromic repeats (CRISPR) in group B Streptococcus (GBS) in the genital tract of women during the third trimester and in infants with invasive infection and its relationship with multilocus sequence typing (MLST) and drug-resistance genes. Methods:This study retrospectively collected 84 GBS strains isolated from pregnant women with GBS colonization and infants with invasive GBS infection who were admitted to Children's Hospital Affiliated to Shanxi Medical University from January 2017 to January 2022. CRISPR, MLST, and drug-resistance phenotype and genes were detected and analyzed using χ 2 test or Fisher exact probability method. MEGA11 was used to construct a dendrogram. Results:There were ten sequence typing in the 84 GBS strains and ST10 was the dominant one (46.4%). GBS was sensitive to penicillin, and its resistance rates to erythromycin (75.0%) and clindamycin (73.8%) were high. Among the 17 invasive GBS strains, ST10 had 100% resistance to erythromycin, clindamycin, and levofloxacin. CRISPR1 gene was amplified in 62 strains (73.8%). CRISPR1-positive strains had a significantly higher proportion of ST10 [56.5%(35/62) vs 18.2%(4/22), χ 2=9.56, P=0.002] and ermB, gyrA, parC [54.8%(34/62) vs 22.7%(5/22), 67.7%(42/62) vs 36.4%(8/22), 71.0%(44/62) vs 36.4%(8/22); χ 2=6.73, 6.64, and 8.25, all P<0.05], and a lower proportion of ermA [6.5%(4/62) vs 31.8%(7/22), χ 2=7.09, P=0.008] than CRISPR1-negative strains. Conclusions:ST10 is the main GBS genotype among the colonized microbiota the genital tract of pregnant women and in infants with invasive GBS infection, which is also a dominant type in CRISPR1-positive strains. GBS is sensitive to penicillin and CRISPR1 gene is linked to the spread of some drug-resistance genes.

Comparison of macrolide resistance, molecular characteristics and MAST types of Bordetella pertussis collected from Xi’an and Shanghai / 西安交通大学学报(医学版)

【Objective】 To compare the macrolide resistance, molecular characteristics and multilocus antigen sequence typing (MAST) of Bordetella pertussis (Bp) collected from Xi’an and Shanghai so as to provide reference for prevention of pertussis and optimize vaccination strategies. 【Methods】 Erythromycin, azithromycin and clarithromycin susceptibility of clinical isolates collected from Xi’an and Shanghai during 2018 and 2019 were determined by E-test. PCR was used to detect the drug-resistant genes and mutation sites. MAST was employed to do molecular typing for the strains. The differences in macrolide resistance and MAST types between Xi’an and Shanghai were compared. 【Results】 Totally 34 strains from Xi’an and 26 strains from Shanghai were isolated. There were differences between Xi’an and Shanghai in the macrolide resistance (χ2=13.650, P<0.001). The composition ratio of MAST types of pertussis strains was also different between Xi’an and Shanghai (χ2=18.642, P<0.001) in that the prn1/ptxP1/ptxA1/fim3-1/fim2-1 strains dominated in Xi’an, while the prn1/ptxP1/ptxA1/fim3-1/fim2-1 and prn2/ptxP3/ptxA1/fim3-1/fim2-1 were almost half and half in Shanghai. A2047G site mutation was detected in all the macrolide-resistant strains, but not in all sensitive strains. Methylase genes ermA and ermB were detected in some macrolide-resistant strains. No other macrolide-resistant genes were found in resistant strains and no mutation or drug resistance gene was found in all the susceptible strains. 【Conclusion】 Differences existed between Xi’an and Shanghai in the macrolide resistance and MAST types of Bordetella pertussis strains. Further monitoring of Bordetella pertussis in China is required to better understand the resistance and evolution of the pathogen.

Drug resistance and virulence characteristics of of Staphylococcus aureus isolated from skin sites of suppurative infections in Inner Mongolia / 中华皮肤科杂志

Objective:To analyze drug resistance, virulence and molecular epidemiological characteristics of Staphylococcus aureus ( S. aureus) isolated from skin sites of suppurative infections, and to provide an experimental basis for clinical anti-infective therapies. Methods:Swab samples from suppurative skin lesions and nasal secretions were collected from inpatients in Department of Dermatology, the Affiliated Hospital of Inner Mongolia Medical University from May 2020 to December 2020, and subjected to bacterial isolation and culture. Suspected S. aureus colonies were identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Drug sensitivity test was conducted by using the broth microdilution method. Virulence genes of S. aureus were amplified by PCR, and real-time fluorescence-based quantitative PCR was performed to determine the relative expression of 4 virulence genes including tsst-1, pvl, hla and clfA in S. aureus strains from different sources. S. aureus strains were genotyped by multilocus sequence typing. Drug resistance rates and detection rates of virulence genes were compared by using chi-square test or Fisher′s exact test, and measurement data among groups were compared by using t test or Mann-Whitney U test. Results:A total of 85 strains of S. aureus were isolated from 210 inpatients, including 54 isolates from skin sites of suppurative infections (case group) and 31 isolates from the nasal cavity (control group) . Drug sensitivity test showed that 14 strains of methicillin-resistant S. aureus (MRSA) were identified among 85 strains of S. aureus. The resistance rate to penicillin was the highest (90.59%, 77/85) in the 85 S. aureus strains; the resistance rates to clindamycin and erythromycin were 60.00% (51/85) and 61.18% (52/85) respectively; no strains showed resistance to rifampicin, vancomycin or linezolid. PCR showed that the detection rate of the pvl gene was 33.33% (18/54) in the case group, which was significantly higher than that in the control group (12.90%, 4/31; χ2= 4.28, P= 0.038) . Real-time fluorescence-based quantitative PCR showed that the relative expression level of the clfA gene was significantly higher in the control group (3.87[2.30, 5.94]) than in the case group (1.63[0.95, 2.62], P= 0.007) . A total of 17 ST types were identified among the 85 strains of S. aureus, and the dominant types were ST398-methicillin-susceptible S. aureus (20/71) and ST22-MRSA (9/14) . The detection rate of the virulence gene pvl was significantly higher in the ST22-MRSA strain (14/14) than in the non-ST22 MRSA strains (0, P < 0.001) . Conclusions:S. aureus strains isolated from the skin sites of suppurative infections were highly resistant to penicillin, clindamycin and erythromycin, so these antibiotics should not be used as the first-choice empiric treatment. The occurrence of cutaneous S. aureus infections may be associated with the virulence gene pvl, and the nasal colonization of S. aureus may be associated with the clfA gene.

Shoot rot of Zizania latifolia and the first record of its pathogen Pantoea ananatis in China / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

The aquatic grass Zizania latifolia grows symbiotically with the fungus Ustilago esculenta producing swollen structures called Jiaobai, widely cultivated in China. A new disease of Z. latifolia was found in Zhejiang Province, China. Initial lesions appeared on the leaf sheaths or sometimes on the leaves near the leaf sheaths. The lesions extended along the axis of the leaf shoots and formed long brown to dark brown streaks from the leaf sheath to the leaf, causing sheath rot and death of entire leaves on young plants. The pathogen was isolated and identified as the bacterium Pantoea ananatis, based on 16S ribosomal RNA (rRNA) gene sequencing, multilocus sequence analysis (atpD (β-subunit of ATP synthase F1), gyrB (DNA gyrase subunit B), infB (translation initiation factor 2), and rpoB (β‍-subunit of RNA polymerase) genes), and pathogenicity tests. Ultrastructural observations using scanning electron microscopy revealed that the bacterial cells colonized the vascular tissues in leaf sheaths, forming biofilms on the inner surface of vessel walls, and extended between vessel elements via the perforated plates. To achieve efficient detection and diagnosis of P. ananatis, species-specific primer pairs were designed and validated by testing closely related and unrelated species and diseased tissues of Z. latifolia. This is the first report of bacterial sheath rot disease of Z. latifolia caused by P. ananatis in China.

Portación nasal, antibiotipo y genotipo de cepas de Staphylococcus aureus aisladas en estudiantes de Medicina y de Enfermería Campus San Felipe, Universidad de Valparaíso, Chile, durante el año 2017 / Nasal carriage, antibiotype and genotype of isolated Staphylococcus aureus from Medicine and Nursing students of Campus San Felipe, University of Valparaiso, Chile, during 2017

INTRODUCCIÓN. Staphylococcus aureus es parte de la microbiota nasal en 20-30% de la población general, colonización que constituye un reservorio para su transmisión, lo que es preocupante en cepas resistentes a meticilina (SARM). OBJETIVO: Determinar la prevalencia de S. aureus en estudiantes de Medicina y Enfermería del Campus San Felipe y caracterizar sus aislamientos. MATERIAL Y MÉTODOS: El 2017 se midió la portación nasal a 225 estudiantes, a las cepas aisladas se le analizó su antibiotipo por difusión en agar, la relación clonal por electroforesis de campo pulsado y MLST. En SARM se determinó el cassette SCCmec y gen de la leucocidina de Panton-Valentine. RESULTADOS: 61 estudiantes portaron S. aureus (27,1%) incluyendo dos cepas SARM (0,9%). Staphylococcus aureus mostró resistencia a penicilina (75%), eritromicina (14%) y clindamicina (10%), cloranfenicol (1,6%) y levofloxacina, oxacilina, cefoxitina (3,3%). Se diferenciaron diecinueve pulsotipos y el secuenciotipo coincidió con complejos clonales descritos a nivel mundial en portadores de S. aureus: CC30, CC8, CC97, CC15, CC22 y CC1. Las dos cepas SARM correspondieron con los clones chileno/cordobés y USA100NY/J, ambas del CC5. CONCLUSIÓN: La portación nasal de S. aureus y SARM en los estudiantes coincidió con la portación en la población general y las cepas sensibles a meticilina mostraron diversidad clonal y alta susceptibilidad antimicrobiana, exceptuando a penicilina.

BACKGROUND: Staphylococcus aureus is part of the nasal microbiota in 20-30% of the population. This colonization is also a reservoir for its dissemination, which is worrying in the case of strains with resistance to methicillin (MRSA). AIM: To determine S. aureus nasal carriage in nursing and medical students of San Felipe Campus and characterize theirs isolates. METHODS: During 2017, nasal swabs were taken from 225 students and seeded in salt manitol agar. Antibiotypes were determined by agar diffusion and the genetic clonality was assessed by PFGE and MLST in isolated S. aureus. SCCmec cassette and Panton-Valentine leukocidin gene (pvl) presence were determined in the MRSA isolates. RESULTS: 61 students carried S. aureus (27.1%) including two MRSA strains (0.9%). S. aureus showed resistance to penicillin (75%), erythromycin (14%) and clindamycin (10%), chloramphenicol (1.6%) and levofloxacin, oxacillin, cefoxitin (3.3%). Nineteen PFGE-types were differentiated, and their sequence-types coincided with main clonal complexes described in S. aureus carriers from different places worldwide: CC30, CC8, CC97, CC15, CC22 and CC1. MRSA strains belonged to CC5 and they corresponded to the Chilean/Cordobes and USA100NY/J clones. CONCLUSION: Nasal carriage of S. aureus and MRSA in students, coincided with the general population and sensitive-methicillin strains showed clonal diversity and high antimicrobial susceptibility except for penicillin.

Genetic diversity and molecular epidemiology of Bordetella pertussis isolates / 中华微生物学和免疫学杂志

Objective:To investigate the genetic diversity and molecular epidemiology of Bordetella pertussis in Shaanxi province, and analyze the possible reasons of resurgence in this region. Methods:We characterized clinical isolates collected during 2012-2017 using multilocus antigen sequence typing (MAST) and multilocus variable-number tandem repeat analysis (MLVA).Results:The circulating strains and vaccine strains were different in molecular characteristics. The majority (95%) of the isolates were typed as prn1/ ptxP1/ ptxA1/ fim3-1/ fim2-1. In addition, eight MLVA types (MTs) and eight PFGE profiles were identified, respectively. MT195, MT55 and MT104 were dominant and MT195 continually increased annually. Conclusions:The genetic characteristics of the current strains in Shaanxi province were different from those of the vaccine strain. The evolution through genetic variation might be one of the reasons for the recurrence of pertussis in this region.