Enterotoxigenic Escherichia coli Multilocus Sequence Types in Guatemala and Mexico

The genetic backgrounds of 24 enterotoxigenic Escherichia coli (ETEC) strains from Mexico and Guatemala expressing heat-stable toxin (ST) and coli surface antigen 6 (CS6) were analyzed. US travelers to these countries and resident children in Guatemala were infected by ETEC strains of sequence type 398, expressing STp and carrying genetically identical CS6 sequences.     

杭州市2002-2008年甲型副伤寒沙门菌分子分型研究

目的研究2002-2008年杭州市甲型副伤寒疫情分离株的亲缘性,并探讨脉冲场凝胶电泳（PFGE）、多位点序列分型（MLST）在甲型副伤寒沙门菌分子分型中的应用。方法对404株甲型副伤寒沙门菌运用脉冲场凝胶电泳（PFGE）进行分子分型,并用K-B法测定菌株抗生素敏感性。挑选9株甲型副伤寒沙门菌进行多位点序列分型（MLST）以及稳定性试验。结果 404株甲型副伤寒沙门菌可分为6个PFGE型和4个耐药型,P1型和P2型属于同一个克隆系,该克隆系菌株占试验菌株数的99%,分离自临安市的310株菌均为P1型,分离自杭州市西湖区的主要菌型是P2型和P1型。9株甲型副伤寒沙门菌根据SucA位点的差异可分为2个MLST型。结论杭州市2002-2008年的甲型副伤寒疫情由同一克隆系的菌株主导。PFGE、MLST分型方法各有侧重,可互为补充。     

临床耐碳青霉烯类肺炎克雷伯菌分子流行病学特征研究

目的 分析近5年耐碳青霉烯类肺炎克雷伯菌的耐药特性及其携带碳青霉烯酶基因等分子流行病学特征,为有效控制院内感染提供依据。方法 收集2012年1月-2016年12月苏州大学附属第二医院临床标本中分离的耐碳青霉烯类肺炎克雷伯菌,用最低抑菌浓度(minimal inhibitory concentration, MIC)法、KB法分析菌株对抗菌药物的敏感性,用改良碳青霉烯灭活试验检测产碳青霉烯酶表型,并通过聚合酶链反应(polymerase chain reaction, PCR)筛选blaKPC、blaNDM、blaIMP、blaVIM和blaOXA48碳青霉烯酶基因,通过脉冲场凝胶电泳(pulsed-field gel electrophoresis, PFGE)和多位点序列分型(multiple locus sequence typing, MLST)检测细菌的同源性和相关遗传性。统计分析相关患者临床资料。结果 共分离到82株耐碳青霉烯类肺炎克雷伯菌,主要来源于呼吸道43株(52.44%),中段尿12株(14.63%),血液10株(12.20%),无菌体液8株(9.76%),分泌物8株(9.76%),导管1株(1.22%),对头孢菌素类和β-内酰胺类抗菌药物表现为高度耐药(85.4%~100%),碳青霉烯灭活试验阳性率为84.1%。PCR检测到71株细菌携带碳青霉烯酶基因,包括KPC阳性56株(78.87%)、NDM阳性10株(14.08%)、IMP阳性4株(5.64%)、VIM阳性1株(1.41%)。感染患者主要集中在重症监护室(ICU)病区(41株,50.00%)和神经外科(14株,17.07%)。2016年检出的32株中有23株(71.9%)PFGE呈高度同源性,且MLST分型均为ST11,其余7株为ST64型(21.9%),2株为ST23型(6.2%)。结论 本院肺炎克雷伯菌主要分布于ICU,以呼吸道标本检出率最高,对碳青霉烯类耐受主要由于产KPC酶,需进一步加强临床耐药细菌的监测,为临床合理使用抗菌药物和严格执行消毒隔离措施提供参考依据。     

Invasive Salmonella enterica Serotype Typhimurium Infections,Democratic Republic of the Congo, 2007–2011

Infection with Salmonella enterica serotype Typhimurium sequence type (ST) 313 is associated with high rates of drug resistance, bloodstream infections, and death. To determine whether ST313 is dominant in the Democratic Republic of the Congo, we studied 180 isolates collected during 2007–2011; 96% belonged to CRISPOL type CT28, which is associated with ST313.     

Genomic Definition of Hypervirulent and Multidrug-Resistant Klebsiella pneumoniae Clonal Groups

Multidrug-resistant and highly virulent Klebsiella pneumoniae isolates are emerging, but the clonal groups (CGs) corresponding to these high-risk strains have remained imprecisely defined. We aimed to identify K. pneumoniae CGs on the basis of genome-wide sequence variation and to provide a simple bioinformatics tool to extract virulence and resistance gene data from genomic data. We sequenced 48 K. pneumoniae isolates, mostly of serotypes K1 and K2, and compared the genomes with 119 publicly available genomes. A total of 694 highly conserved genes were included in a core-genome multilocus sequence typing scheme, and cluster analysis of the data enabled precise definition of globally distributed hypervirulent and multidrug-resistant CGs. In addition, we created a freely accessible database, BIGSdb-Kp, to enable rapid extraction of medically and epidemiologically relevant information from genomic sequences of K. pneumoniae. Although drug-resistant and virulent K. pneumoniae populations were largely nonoverlapping, isolates with combined virulence and resistance features were detected.     

Molecular epidemiology and genetic diversity of pneumococcal carriage among children in Beni State, Bolivia

During 2007, a study of pneumococcal carriage in children was performed in two towns (Trinidad and Riberalta) in the Beni region of the Bolivian Amazon basin. Little has previously been reported regarding the epidemiology of pneumococcal carriage in Bolivia, and no multilocus sequence typing (MLST) of pneumococcal isolates from this region has previously been documented. A pneumococcal carriage rate of 34% was identified. Of 53 Streptococcus pneumoniae isolates that survived transportation for serotyping, antibiotic susceptibility testing and MLST, the commonest serotypes were 6A (9%), 34 (8%), 4 (6%), 9A (6%), 10A (6%), 19A (6%), 23F (6%) and 38 (6%); overall, 26 different serotypes were identified. Antibiotic susceptibility testing by Etest demonstrated high levels of susceptibility to penicillin (93%), erythromycin (98%), vancomycin (100%), chloramphenicol (100%), tetracycline (96%) and trimethoprim/sulfamethoxazole (co-trimoxazole) (85%). MLST identified that the majority (57%) of viable isolates belonged to previously unrecognised sequence types that are currently unique to Bolivia.     

乡村医疗机构与城市医院来源的艰难梭菌MLST分型对比研究

目的 初步了解农村社区艰难梭菌流行状况及分子生物学特征.方法 对河南省济源市某乡村医疗机构送检的7株艰难梭菌进行生化鉴定和分子生物学方法鉴定,并进行MLST分型分析,同时与北京某三甲医院的84株艰难梭菌进行对比,用eBURST软件聚类分析,寻找其中可能的关联.结果 源自河南济源市某乡村医院的7株菌均属艰难棱菌,PCR毒素基因鉴定结果显示,其中两株为A-B+菌株,其MLST分型结果是ST37;5株为A+B+菌株,其中4株对应ST35,1株对应ST3;两重来源的菌株中均是毒素基因A+B+菌株占优势;乡村医疗机构的7株艰难棱菌中未发现新的与David MLST数据库中不同的ST型别,未发现不同于北京城市医院的ST型别.结论 David方案适合种群结构和全球流行病学研究,且其数据库全球共享,便于数据交换;该次研究中未发现新的ST型别,所有菌株ST呈散在分布.     

Pneumococcal carriage among children after four years of routine 10-valent pneumococcal conjugate vaccine use in Brazil: The emergence of multidrug resistant serotype 6C

BackgroundIn 2010, the 10-valent pneumococcal conjugate vaccine (PCV10) was introduced free of charge in Brazil as part of the public immunization program. Here we investigated the carriage prevalence, colonization risk factors, capsular types, and antimicrobial resistance among pneumococcal isolates obtained from children in Brazil four years after routine PCV10 use.MethodsBetween September and December 2014, we conducted a cross-sectional study among children < 6 years old who attended one public and two private clinics in Niterói, RJ, Brazil to evaluate pneumococcal nasopharyngeal carriage. Antimicrobial susceptibility and capsular types were determined for all isolates.ResultsOf 522 children, 118 (22.6%) were pneumococcal carriers. Being ≥ 2 years old, attending childcare center, presenting with any symptoms, having acute or chronic respiratory disease, and residing in a slum were associated with pneumococcal carriage. The most prevalent capsular types were 6C (14.5%), 15B/C (11.5%), 11A/D (9.2%), and 6A (7.6%). PCV10 serotypes represented 2.5%. All isolates were susceptible to levofloxacin, rifampicin, and vancomycin. Penicillin non-susceptible pneumococci (PNSP) comprised 39%, with penicillin and ceftriaxone MICs ranging from 0.12–8.0 μg/ml and 0.012–1.0 μg/ml, respectively. The 33 (28%) erythromycin-resistant isolates (MICs of 1.5 to >256 μg/ml) displayed the cMLS_B (72.7%) or M (27.3%) phenotypes, harboring the erm(B) and/or mef(A/E) genes. High non-susceptibility rates (>20%) to clindamycin, erythromycin, penicillin, and tetracycline were largely explained by the prevalence of multidrug resistant (MDR) serotype 6C isolates.ConclusionsEffects of universal childhood PCV10 use on carriage were evident, with the near elimination of PCV10 serotypes. The emergence of MDR serotype 6C isolates, however, is a concern. Ongoing surveillance to monitor serotype 6C increase in invasive diseases is warranted.     

Pathogenic potential to humans of bovine Escherichia coli O26, Scotland

Escherichia coli O26 and O157 have similar overall prevalences in cattle in Scotland, but in humans, Shiga toxin-producing E. coli O26 infections are fewer and clinically less severe than E. coli O157 infections. To investigate this discrepancy, we genotyped E. coli O26 isolates from cattle and humans in Scotland and continental Europe. The genetic background of some strains from Scotland was closely related to that of strains causing severe infections in Europe. Nonmetric multidimensional scaling found an association between hemolytic uremic syndrome (HUS) and multilocus sequence type 21 strains and confirmed the role of stx(2) in severe human disease. Although the prevalences of E. coli O26 and O157 on cattle farms in Scotland are equivalent, prevalence of more virulent strains is low, reducing human infection risk. However, new data on E. coli O26-associated HUS in humans highlight the need for surveillance of non-O157 enterohemorrhagic E. coli and for understanding stx(2) phage acquisition.     

International spread of major clones of methicillin resistant staphylococcus aureus: nosocomial endemicity of multi locus sequence type 239 in Saudi Arabia and Romania

Phenotypically identified methicillin resistant Staphylococcus aureus (MRSA) strains from several hospitals in Romania and Saudi Arabia (n = 103 and 68, respectively) were confirmed to be MRSA by mecA PCR and PBP-2' based latex agglutination. Subsequently, strains were differentiated at the sub-species level using pulsed field gel electrophoresis (PFGE) of SmaI DNA macro-restriction fragments. Comparison of the PFGE fingerprints identified major clusters of strains, persistently present in the various hospitals. Endemicity of certain strains was identified, amongst others one due to a particularly methicillin resistant type in the burn wound sector of the Romanian hospital. No PFGE-based overlap was found between the Saudi and Romanian strains. However, multi locus sequence typing (MLST), performed for 20% of all strains, revealed that genuine genetic similarity was obscured by the PFGE analysis. In both the Romanian and Saudi hospitals the renowned sequence type (ST) 239 was very over-represented. This was especially apparent in Saudi Arabia, where all strains except two shared the ST 239 genotype. This clonal type has previously been identified in a variety of other countries. Despite the MLST concordance, PFGE data indicate that ST 239 diversifies while maintaining its core genome intact. ST 80, another previously but less frequently identified clone, was introduced in 2000 in the Romanian institutes and persisted over the past 3 years as a frequent cause of infections in a surgical department. The successful MRSA types can acquire prominent positions in hospitals of previously low-endemicity MRSA status.