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.

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.

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.

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.

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.

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.

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.

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.

Distribution of virulence genes and the molecular epidemiology of Streptococcus pyogenes clinical isolates by emm and multilocus sequence typing methods

@#Background: Streptococcus pyogenes has a variety of virulence factors and the predominant invasive strains differ according to specific emm types and geographical orientation. Although emm typing is commonly used as the gold standard method for the molecular characterisation, multilocus sequence typing (MLST) has become an important tool for comparing the genetic profiles globally. This study aimed to screen selected virulence genes from invasive and non-invasive clinical samples and to characterise the molecular epidemiology by emm typing and MLST methods. Materials and Methods: A total of 42 S. pyogenes isolates from invasive and non-invasive samples collected from two different tertiary hospitals were investigated for the distribution of virulence factors and their molecular epidemiology by emm and multilocus sequence typing methods. Detection of five virulence genes (speA, speB, speJ, ssa and sdaB) was performed using multiplex polymerase chain reaction (PCR) using the standard primers and established protocol. Phylogenetic tree branches were constructed from sequence analysis utilised by neighbour joining method generated from seven housekeeping genes using MEGA X software. Results: Multiplex PCR analysis revealed that sdaB/speF (78.6%) and speB (61.9%) were the predominant virulence genes. Regardless of the type of invasiveness, diverse distribution of emm types/subtypes was noted which comprised of 27 different emm types/subtypes. The predominant emm types/subtypes were emm63 and emm18 with each gene accounted for 11.8% whereas 12% for each gene was noted for emm28, emm97.4 and emm91. The MLST revealed that the main sequence type (ST) in invasive samples was ST402 (17.7%) while ST473 and ST318 (12% for each ST) were the major types in non-invasive samples. Out of 18 virulotypes, Virulotype A (five genes, 55.6%) and Virulotype B (two genes, 27.8%) were the major virulotypes found in this study. Phylogenetic analysis indicated the presence of seven different clusters of S. pyogenes. Interestingly, Cluster VI showed that selected emm/ST types such as emm71/ST318 (n=2), emm70.1/ST318 (n=1), emm44/ST31 (n=1) and emm18/ST442 (n=1) have clustered within a common group (Virulotype A) for both hospitals studied. Conclusion: The present study showed that group A streptococcci (GAS) are genetically diverse and possess virulence genes regardless of their invasiveness. Majority of the GAS exhibited no restricted pattern of virulotypes except for a few distinct clusters. Therefore, it can be concluded that virulotyping is partially useful for characterising a heterogeneous population of GAS in hospitals.

Diseminación clonal de KPC-2 en Klebsiella pneumoniae resistente a carbapenémicos / Clonal dissemination of KPC-2 in carbapenem resistant Klebsiella pneumoniae

Objetivo: Determinar los mecanismos de resistencia antibiótica y la epidemiología molecular de aislados clínicos de Klebsiella pneumoniae resistentes a carbapenémicos. Materiales y métodos: 30 aislados multirresistentes de K. pneumoniae fueron obtenidos a partir de: urocultivo, aspirado traqueal, secreción de herida, sonda vesical, hemocultivo, líquido peritoneal, punta de catéter, colección abdominal y secreción bronquial. Los aislados fueron colectados de noviembre de 2012 a abril de 2013. La identificación y susceptibilidad antibiótica fue determinada por el sistema automatizado VITEK 2. Para la amplificación de genes de resistencia se empleó PCR, la determinación de las Secuencias Tipo (ST) fue obtenida por tipificación multilocus de secuencias (MLST) y la relación clonal fue establecida por electroforesis en gel de campo pulsado (PFGE). Resultados: Todos los aislados mostraron fenotipos multirresistentes, excepto a colistina y tigeciclina. El 100% de los aislados fue productor de la carbapenemasa KPC-2. La determinación de la presencia de genes codificantes de β-lactamasas de Espectro Extendido mostró que el 67% de los aislados fue positivo para el gen blaCTX-M, el 100% fue positivo para el gen blaSHV y 93% fue positivo para el gen blaTEM. El análisis de la relación clonal de los 30 aislados agrupó a 20 en un mismo pulso tipo. El análisis por MLST demostró que la ST predominante fue ST258 presente en el 60% de la población, seguida de ST1199 presente en el 20% de la población analizada. Conclusiones: Los resultados obtenidos demuestran la importancia de implementar y combinar estudios epidemiológicos, clínicos y moleculares para comprender la distribución de la resistencia entre bacterias de interés clínico.

Objective: To determine the mechanism of antibiotic resistance and molecular epidemiology of carbapenem resistant isolates of Klebsiella pneumoniae. Materials and Methods: 30 multidrug resistant isolates of K. pneumoniae were obtained from urine culture, tracheal aspirate, wound secretion, bladder catheter, blood culture, peritoneal fluid, catheter tip, abdominal collection, and bronchial secretion. K. pneumoniae isolates were collected between November 2012 and April 2013. Identification and susceptibility were determined by the VITEK 2 system. Resistance genes were identified by PCR, sequence type (ST) was established by multilocus sequence typing (MLST), and clonal relationship was defined by pulsed field gel electrophoresis (PFGE). Results: All isolates were multidrug resistant and susceptible to colistin and tigecycline. 100% of isolates produced KPC-2 carbapenemase. This study detected Extended Spectrum β-Lactamases enconding genes. 67% of isolates were positive for blaCTX-M, 100% were positive for blaSHV, and 93% of isolates were positive for blaTEM. Analysis of the clonal relationship clustered 20 isolates in the same clonal complex. Multilocus sequence typing showed the predominant sequence type ST 258 in 60% of population. ST 1199 were present in 20% of bacterial population. Conclusion: Molecular epidemiology, clinical research and molecular biology studies improve understanding of mechanisms of resistance distribution among bacteria of clinical interest.

Clinical and microbiological characteristics of cryptococcosis at an university hospital in China from 2013 to 2017

ABSTRACT Background: This study aims to explore the epidemiology, clinical profile and strain characteristics of cryptococcosis from 2013 to 2017 in a major teaching hospital in China. Methods: Trends in antifungal drug susceptibility of 217 consecutive non-repetitive cryptococcal isolates collected from patients of an university hospital in China were analyzed between 2013 and 2017. Of those, 98 isolates were conserved for identification by internal transcribed spacer (ITS) sequencing and matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system. Multilocus sequence typing (MLST) was used to designate molecular types. Clinical characteristics of the 98 patients with cryptococcosis during the period of 2013-2017 were retrospectively evaluated. Results: There was a trend for gradual increase in the MIC range of fluconazole was from 2013 to 2017. The conserved 98 clinical cryptococcal isolates included 97 C. neoformans and one C. gattii, and 90 (91.8%) isolates belonged to ST5 genotype VNI. Out of the 98 patients with cryptococcosis, 28 (28.6%) were HIV-infected and 32 (32.7%) had no underlying diseases. HIV-infected patients had higher mortality than HIV-uninfected patients (28.6% vs 14.3%, p = 0.147). Conclusions: Most of the patients with cryptococcosis were not HIV-infected in this study, while patients with HIV had a higher mortality. Reduced susceptibility to fluconazole was observed among C. neoformans isolates, most of them belonged to ST5 genotype VNI having an impact on the effective dose of fluconazole.

Multilocus sequence typing (MLST) of clinical and environmental isolates of Cryptococcus neoformans and Cryptococcus gattii in six departments of Colombia reveals high genetic diversity

Abstract INTRODUCTION: The average annual incidence of cryptococcosis in Colombia is 0.23 cases per 100,000 inhabitants in the general population, and 1.1 cases per 1000 in inhabitants with Acquired Immune Deficiency Syndrome (AIDS). In addition, the causal fungus has been isolated from the environment, with serotypes A-B and C in different regions. This study aims to determine the genetic association between clinical and environmental isolates of C. neoformans/C. gattii in Colombia. METHODS: Multilocus sequence typing (MLST) was used to identify possible clones, providing information about the epidemiology, ecology, and etiology of this pathogen in Colombia. RESULTS: A total of 110 strains, both clinical (n=61) and environmental (n=49), with 21 MLST sequence types (ST) of C. neoformans (n=14STs) and C. gattii (n=7STs) were identified. The STs which shared clinical and environmental isolate sources were grouped in different geographical categories; for C. neoformans, ST93 was identified in six departments, ST77 in five departments; and for C. gattii, ST25 was identified in three departments and ST79 in two. CONCLUSIONS: High genetic diversity was found in isolates of C. neoformans/gattii by MLST, suggesting the presence of environmental sources harboring strains which may be sources of infection for humans, especially in immunocompromised patients; these data contribute to the information available in the country on the distribution and molecular variability of C. neoformans and C. gattii isolates recovered in Colombia.

Molecular epidemiology of Listeria monocytogenes isolated from ready-to-eat food in 2017 in China / 中华预防医学杂志

To analyze the molecular characteristics of strains from ready-to eat food in China. A total of 239 strains isolated from ready-to-eat food in 2017, all strains underwent whole-genome sequencing (WGS) , and comparisons uncovered population structure derived from lineages, clonal complex, serogroups, antimicrobial susceptibility and virulence, which were inferred in silico from the WGS data. Core genome multilocus sequence typing was used to subtype isolates. All strains were categorized into three different lineages, lineage Ⅱ was the predominant types in food, and IIa was the main serogroups. CC8, CC101 and CC87 were the first three prevalent CCs among 23 detected CCs, accounting for 49.4%. Only 4.6% (11 isolates) of tested strains harbored antibiotic resistance genes, which were mostly trimethoprim genes (7 isolates, 2.9%). All strains were positive for LIPI-1, and only a part of strains harbored LIPI-3 and LIPI-4, accounting for 13.8% (33 isolates) and 14.2% (34 isolates), respectively. ST619 carried both LIPI-3 and LIPI-4. 51.5% (123 isolates) of strains carried SSI-1, and all CC121 strains harbored SSI-2. Different lineages, serogroups and CCs can be separated obviously through cgMLST analysis, and 24 sublineages were highly concordant with CCs. Ⅱa was the main serogroups in ready-to-eat food isolates in China; CC8, CC101 and CC87 were the prevalent CCs, and CC87 isolates was hypervirulent isolates, cgMLST method can be adopted for prospective foodborne disease surveillance and outbreaks detection.

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.

Multilocus Sequence Typing Analysis of Invasive and Non-Invasive Group B Streptococcus of Hospital Origin in Malaysia

@#The aim of this study was to study the genotype of a hospital collection of Group B Streptococcus (GBS) from invasive and non-invasive sites. Fifty-one pre-characterised human of GBS were re-identified and further analysed by multilocus sequence typing (MLST) in relation to previously published serotypes. Fifteen sequence types (ST) were found with ST1 being the most predominant. ST1 was also associated with majority of the invasive isolates. The genotypic distribution patterns of GBS in this study were largely in agreement with previous reports from other countries indicating the tendency of certain genotypes to prevail in human infection settings.

Molecular epidemiology of Listeria monocytogenes isolated from ready-to-eat food in 2017 in China / 中华预防医学杂志

Objective@#To analyze the molecular characteristics of Listeria monocytogenes strains from ready-to eat food in China.@*Methods@#A total of 239 Listeria monocytogenes strains isolated from ready-to-eat food in 2017, all strains underwent whole-genome sequencing (WGS) , and comparisons uncovered population structure derived from lineages, clonal complex, serogroups, antimicrobial susceptibility and virulence, which were inferred in silico from the WGS data. Core genome multilocus sequence typing was used to subtype isolates.@*Results@#All strains were categorized into three different lineages, lineage Ⅱ was the predominant types in food, and IIa was the main serogroups. CC8, CC101 and CC87 were the first three prevalent CCs among 23 detected CCs, accounting for 49.4%. Only 4.6% (11 isolates) of tested strains harbored antibiotic resistance genes, which were mostly trimethoprim genes (7 isolates, 2.9%). All strains were positive for LIPI-1, and only a part of strains harbored LIPI-3 and LIPI-4, accounting for 13.8% (33 isolates) and 14.2% (34 isolates), respectively. ST619 carried both LIPI-3 and LIPI-4. 51.5% (123 isolates) of strains carried SSI-1, and all CC121 strains harbored SSI-2. Different lineages, serogroups and CCs can be separated obviously through cgMLST analysis, and 24 sublineages were highly concordant with CCs.@*Conclusion@#Ⅱa was the main serogroups in ready-to-eat food isolates in China; CC8, CC101 and CC87 were the prevalent CCs, and CC87 isolates was hypervirulent isolates, cgMLST method can be adopted for prospective foodborne disease surveillance and outbreaks detection.

Performance verification of a time-of-flight mass spectrometry based cardiovascular drug-related polygene detection system / 中华检验医学杂志

Objective@#Toestablish and verify the method of genetic polymorphisms using time-of-flight mass spectrometry as a polygene testing platform.@*Methods@#998 cases of DNA samples and 20 cases of whole blood samples were collected from Fuwai hospital of Chinese academy of medical sciencesduring September 2017 to October 2018, including 512 cases of males and 506 cases of females.280 patients aged 18-30, 442 patients aged 31-64, and 296 patients aged ≥65.11 cardiovascular drugsrelatedgenes in 998 DNA samples were detected by time-of-flight mass spectrometry to evaluate the compliance rate compared with identifiedresults. 20whole blood samples were selected to detect 11 genes using both time-of-flight mass spectrometry and Sanger sequencing. The results were compared twice, and accuracy was evaluated according to Sanger sequencing as the gold standard. Ten cases of genomic DNA with wild-type loci were selected for specific evaluation by time-of-flight mass spectrometry. Samples containing all heterozygous genotypes were measured after gradient dilution to evaluate the detection sensitivity of the new method. Samples containing all 49 genotypes (two genotypes were not found because they are rare in Chinese population) were used in order to do the inter-assay and intra-assay precision evaluation. An anti-interference study was performed by selecting wild and homozygous mutant samples of represented heterozygous peak shape.@*Results@#The results showed that the compliancerate of the single retrospective sample was over 99.5%. The resultsof time-of-flight mass spectrometry and Sanger sequencing was the same. The minimum detection limit of DNA was 0.4 ng, the inter-assay and intra-assay precision were 100%, and the degradation ability of the UNG enzyme was 105 copies/μl in aerosol.The reaction system has a strong anti-interference ability to the genome and intermediate aerosol, and no cross-contamination between different matrices of the chip.@*Conclusions@#The time-of-flight mass spectrometry as a polygene detection system shows agood detection performance and can be applied to clinical detection. In addition, this paper established a performance verification research scheme based on the time-of-flight mass spectrometry platform polygene detection system.