Background:Staphylococcus aureus (S. aureus) was a prevalent pathogenic bacterium among children. Due to the extensive use of antibiotics, the sensitivity of S. aureus to these drugs has gradually declined. Since the 1960s, methicillin-resistant Staphylococcus aureus (MRSA) has emerged and spread worldwide, becoming a primary cause of both healthcare-associated (HA) and community-acquired (CA) infections. This retrospective study aimed to highlight the significance of S. aureus among bacteria isolated from children in Beijing, China, and to elucidate its antimicrobial resistance patterns. Methods:Data on all S. aureus infections from 2013 to 2022 were collected from the microbiology department of Beijing Children's Hospital. Only the first isolate from the same kind of specimen was analyzed. Antimicrobial susceptibility tests were carried out by Vitek 2 automated system (bio Mérieux, France) or Kirby-Bauer disc diffusion method, according to the guidelines recommended by the Clinical and Laboratory Standards Institute (CLSI). Results:During the decade-long research period, a total of 47,062 bacterial isolates were isolated from 433,081 submitted specimens, with 6477 of these isolates identified as S. aureus. The majority of patients with S. aureus infections belonged to the age group of infants under one-year-old, accounting for 37.9% of cases. S. aureus isolates were predominantly found in the Pneumology Department, and the most common source of these isolates was lower respiratory tract specimens, comprising 34.3% of the total. The resistance rates of S. aureus to penicillin and erythromycin were notably high, at 89.5% and 73.8%, respectively. In contrast, the resistance rates to linezolid, vancomycin, rifampicin, and moxifloxacin were remarkably low, at 0.0%, 0.0%, 1.3%, and 3.9%, respectively. The detection rate of MRSA was 27.8%. MRSA isolates were predominantly found in the newborn group, ICU, and sterile body fluids. Conclusion:In our study, the most prevalent specimen type was derived from the lower respiratory tract, whereas the highest positive rate was observed in ear secretions. These findings underscored the pressing necessity for ongoing antimicrobial resistance (AMR) surveillance and the revision of treatment guidelines, particularly given the elevated detection of MRSA in ICU wards, sterile body fluids, and the neonatal age group. MRSA exhibited significant resistance to all β-lactam antibiotics, erythromycin, and ciprofloxacin. Therefore, future research endeavors should prioritize examining specific antimicrobial resistance populations and potential intervention strategies, as these were vital in mitigating the dissemination of antimicrobial-resistant isolates.

Introduction:Streptococcus pneumoniae (S. pneumoniae) is a major pathogen causing death in children. Few studies have evaluated the importance of S. pneumoniae in the identified bacteria in clinical work. This retrospective study aimed to reveal the rank of S. pneumoniae in determined bacteria isolated from children in Beijing, China, as well as the antimicrobial resistance of this pathogen.Methods:The number of specimen for bacterial culture and of bacterial species were cumulated and ranked based on the data of the two largest children's hospitals in Beijing from 2015 to 2021. The temporal change of S. pneumoniae culture, as well as the clinical data of S. pneumoniae isolates were collected and analyzed. The minimum inhibitory concentrations of antimicrobial agents were determined by BD Phoenix 100 automated system or Vitek 2 automated system for antimicrobial susceptibility testing. The breakpoints recommended by CLSI were adopted.Results:During the 7-year study period, a total of 45,631 bacterial isolates were cultured from 462,144 submitted specimens, in which S. pneumoniae was the third frequent agent following S. aureus and H. influenza, and accounting for 8.79% of the isolates (4011/45,631). In the 4011 S. pneumoniae isolates, 2239 and 997 ones were, respectively, isolated from sputum and bronchial lavage fluid. Most of S. pneumoniae strains were identified in winter (34.7%) and spring (26.1%), and were mainly isolated from patients under 5 years old (77.1%). Low susceptible rate (27.6%) of CSF isolates was determined to penicillin according to the parenteral meningitis breakpoints, while high susceptible rate (56.9%) of non-CSF isolates was obtained according to the parenteral non-meningitis breakpoints. The isolates showed low sensitivity to erythromycin and tetracycline (<5%). All isolates were susceptible to vancomycin and linezolid.Conclusion:The present results demonstrated that S. pneumoniae was one of the most commonly detected bacteria in current pediatric clinical tests, especially in young children under 5 years old, which emphasized the importance of prevention. Penicillin could still be the first empiric choice to treat non-meningitis pneumococcal infections, while erythromycin should not be involved in the treatment.

Purpose:Bloodstream infections (BSIs) was an essential cause of morbidity and mortality in children. Empiric broad-spectrum treatment of BSIs may be costly and unable to effectively eliminate the correct pathogenic microbes, resulting in downstream antimicrobial resistance. The purpose was to provide evidence for diagnosis and treatment of bloodstream infections in pediatrics, by revealing the pathogen distribution and antibiotic resistance pattern of BSIs.Methods:In this 5-year study, a total of 2544 pathogenic bacteria stains, isolated from 2368 patients with BSI, were retrospectively analyzed, to define the species distribution and the antimicrobial resistance pattern in Beijing.Results:The most frequently isolated pathogenic bacteria were K. pneumoniae (12.1%), S. aureus (11.5%), E. coli (11.2%), and E. faecium (11.2%). Hematological malignancies were the most common disease among patients with underlying conditions. Methicillin resistance was detected in 30.0% of S. aureus and 81.7% of coagulase-negative Staphylococcus (CoNS), respectively. The detection rates of carbapenem-resistant-E. coli (CRECO) and carbapenem-resistant-K. pneumoniae (CRKPN) were 10.8% and 50.8%, respectively. In terms of 122 isolates of S. pneumonia, 5 isolates (4.1%) were penicillin-resistant Streptococcus pneumoniae (PRSP); meanwhile, 50 isolates (41.0%) were penicillin-intermediate Streptococcus pneumoniae (PISP). Among the non-fermentative gram-negative bacilli isolates, 22.8% and 26.9% of the P. aeruginosa, were resistant to imipenem and meropenem. Furthermore, the resistance rates of A. baumannii to imipenem and meropenem both were 54.5%.Conclusion:In the study, we demonstrated the characteristics of bloodstream infections and antimicrobial susceptibility pattern of pediatrics in Beijing. Gram positive bacteria were the main pathogens of BSIs. CoNS strains presented even higher resistance to multiple antibiotics, including methicillin, than S. aureus. K. pneumoniae and E. coli represent the most common isolated gram-negative bacteria and exhibited high resistance to a variety of antimicrobial agents. Therefore, it was of critical importance to implement appropriate antimicrobial medication according to pathogen distribution and drug susceptibility test.

Background This study was aimed to investigate the clinical and molecular epidemiology of Staphylococcus aureus ( S. aureus ) isolated from Chinese children and determine the possible relationship among the accessory gene regulator ( agr ) groups and genotypes, as well as among the virulence genes and disease types. Methods S. aureus strains were isolated from Beijing Children’s Hospital between October 2017 and October 2019. The isolates and 19 virulence genes were characterized using multi-locus sequence typing, staphylococcal protein A ( spa ), staphylococcal cassette chromosome mec , and agr typing. Results A total of 191 non-repetitive S. aureus clinical isolates were divided into 33 sequence types (STs), 18 clonal complexes (CCs), and 59 spa types. ST59 (39.8%), t437 (37.7%), and agr I (84.8%) were the predominant types. CC59, CC25, CC22, CC951, CC8, and CC398 belonged to agr I. CC5 and CC15 were assigned to agr II, and CC30 was characterized as agr III. CC121 was classified under agr IV. The eta , etb , and bbp genes were more prevalent in agr IV ( P < 0.001 for each), while tst was more prevalent in agr group III compared to the other groups ( P < 0.001). Nearly all isolates that harbored lukS/F-PV belonged to agr I ( P = 0.005). However, the correlation between disease types and agr groups was not significant ( P > 0.05). Conclusions An association among the agr groups and genotypes, as well as specific toxin genes, was observed among the S. aureus strains isolated from Chinese children. However, a statistical correlation was not found among the agr groups and disease types.

目的 了解首都医科大学附属北京儿童医院临床分离流感嗜血杆菌相关临床资料及对抗菌药物的耐药率,为临床合理使用抗菌药物提供依据.方法 收集2015年1月1日—2019年12月31日该院儿童患者临床分离的3026株非重复流感嗜血杆菌,采用纸片扩散法进行药敏试验,应用WHONET 5.6软件对药敏结果进行分析.结果 流感嗜血杆菌感染多见于婴幼儿,以呼吸道感染为主,多见于冬春季.分离的流感嗜血杆菌中1760株(58.2％)产β内酰胺酶,92株(3.0％)为β内酰胺酶阴性氨苄西林耐药菌株.流感嗜血杆菌对甲氧苄啶-磺胺甲唑的耐药率最高,为66.1％,其次为氨苄西林(61.2％)、头孢克洛(43.8％)、头孢呋辛(35.5％)和阿莫西林-克拉维酸(19.6％),对阿奇霉素和头孢唑肟的不敏感率分别为35.8％和5.1％,未检出对头孢曲松和美罗培南不敏感菌株.结论 儿童患者分离的流感嗜血杆菌β内酰胺酶阳性率很高,是对氨苄西林耐药的主要机制,氨苄西林已不能作为临床治疗流感嗜血杆菌感染的一线用药.流感嗜血杆菌对抗菌药物的耐药率逐年升高,临床应根据药敏结果合理选用抗菌药物,减缓耐药菌株的产生.

化脓性脑膜炎是儿童常见的中枢神经系统感染疾病,发病率高、病情重,进展迅速,临床上严重威胁患儿的生命,早期诊断和正确的抗感染尤其重要.脑脊液细菌培养和药敏是诊断中枢神经系统感染的金标准,为临床合理使用抗菌药物,改善患儿的症状和预后提供重要依据.为了解北京儿童医院门诊及住院患儿中枢神经系统感染的病情及耐药情况,对2016-2018年脑脊液培养阳性结果进行回顾性分析,报道如下.

Background: Hypervirulent variants of Klebsiella pnuemoniae (hvKp) are emerging globally causing life-threatening infectious diseases; however, comprehensive studies on pediatric hvKp strains and related infections are still lacking. Methods: Clinical data were collected from medical records. Genotype (multilocus sequence typing), capsular serotype, virulence gene profile and carbapenemase of the isolates were determined by PCR and DNA sequencing. Broth microdilution method was adopted to test the antimicrobial susceptibility. Hypermucoviscosity phenotype and the virulence of the strains were evaluated by string test and Galleria mellonella larvae killing assay. Results: Among 319 K. pneumoniae strains, 26 (8.2%) hvKp were identified, the detection rates in 2017, 2018 and 2019 were 1.8%, 5.2% and 11.3%. The majority of hvKp infections were found in school-age children and adolescents (57.7%). Pneumonia was the most common diagnosis (38.5%). Single fatal case was hvKp caused liver abscess complicated with bacteremia. hvKp were dominated by ST23 (30.8%) and ST11 (30.8%). Eight carbapenem-resistant hvKp (CR-hvKp) were found, which all belonged to ST11. Virulence gene profile revealed that ST11 hvKp might carry incomplete pLVPK-like plasmids, but they exhibited comparable in vivo virulence to the other hvKp. Conclusions: The infections caused by hvKp are not frequent among pediatric populations, but the detection rate of hvKp in pediatric populations is increasing rapidly in recent years. The emerging and dissemination of ST11 CR-hvKp should be monitored continuously.

目的 了解某医院住院患儿侵袭性肺炎链球菌感染的临床特征以及菌株的血清型和耐药性,以期指导临床合理用药,寻找防治侵袭性肺炎链球菌感染的有效方法.方法 回顾性分析2014年1月—2018年12月该院明确诊断为侵袭性肺炎链球菌感染患儿的临床资料,肺炎链球菌的药敏结果、血清型,以及疫苗对其血清型覆盖情况.结果 74例侵袭性肺炎链球菌感染患儿主要为幼儿期患儿(55.4％),感染部位主要以单部位血液为主(44.6％).74株肺炎链球菌,其中22株分离自脑脊液标本,分为13种血清型,常见的血清型为19F、19A、14和23F.青霉素不敏感肺炎链球菌(PNSP)检出率为56.7％(42株),未发现对利奈唑胺、万古霉素、莫西沙星和左氧氟沙星耐药的肺炎链球菌.不同血清型菌株的耐药率有明显差异,血清型19F和19A对青霉素、头孢噻肟、头孢吡肟和美罗培南的耐药率高于其他血清型.肺炎链球菌疫苗对肺炎链球菌的覆盖率:PCV7为63.5％,PCV13为97.3％.结论 该医院住院患儿侵袭性肺炎链球菌感染多见于婴幼儿,分离的肺炎链球菌血清型以19F、19A、14、23A为主,PCV13对这些血清型覆盖率高,可通过接种疫苗减少侵袭性肺炎链球菌感染的发生.流行率高的血清型往往表现出更高的耐药性,应根据药敏试验结果合理选用抗菌药物.

目的 了解2019年首都医科大学附属北京儿童医院临床分离细菌分布及其对抗菌药物的耐药性.方法 收集2019年1月1日—12月31日该院临床分离的4 854株非重复细菌,采用纸片扩散法、仪器法、部分抗菌药物补充E试验法进行药敏试验,应用WHONET 5.6软件对药敏结果进行分析.结果 4 854株非重复细菌中,革兰阳性细菌占48.3%,革兰阴性细菌占51.7%.金黄色葡萄球菌占16.8%,其次为流感嗜血杆菌、克雷伯菌属、肺炎链球菌.标本主要来自呼吸道(39.4%)、血液(22.1%)和尿液(10.8%).金黄色葡萄球菌、表皮葡萄球菌和其他凝固酶阴性葡萄球菌中甲氧西林耐药株(MRSA、MRSE和其他MRCNS)分别占各自菌种的26.7%、83.1%和80.5%,检出3株表皮葡萄球菌和1株松鼠葡萄球菌对利奈唑胺耐药.肠球菌属中检出2株利奈唑胺耐药粪肠球菌和2株利奈唑胺中介屎肠球菌.脑脊液中分离出13株肺炎链球菌,其中青霉素耐药肺炎链球菌(PRSP) 8株,占61.5% ;非脑脊液标本分离出350株肺炎链球菌,其中PRSP和青霉素中介肺炎链球菌(PISP)分别占2.6%和25.7%.克雷伯菌属(肺炎克雷伯菌和产酸克雷伯菌)、大肠埃希菌和奇异变形杆菌中产ESBL菌株的检出率分别为70.0%、69.9%和26.1%.肠杆菌、鲍曼不动杆菌、铜绿假单胞菌中碳青霉烯类耐药株(CRE、CRAB、CRPAE)分别占27.1%、71.0%和21.0%.535株流感嗜血杆菌对氨苄西林耐药率为71.2%,β内酰胺酶阳性率为69.2%.结论 临床分离的常见细菌对不同抗菌药物的耐药率不同,应重视细菌耐药监测,合理使用抗菌药物.

Background Staphylococcus aureus ( S. aureus ) accessory gene regulator ( agr ) system plays a critical role in staphylococcal pathogenesis. Our study aimed to investigate the relationship between agr group, the genetic background, virulence genes and disease types distribution of S. aureus isolated from different clinical sources among Chinese children.Methods S. aureus strains were isolated from Beijing Children’s hospital from October 2017 to October 2019. Isolates were typed by multilocus sequence typing (MLST), staphylococcal protein A ( spa ), agr, and staphylococcal cassette chromosome mec (SCC mec ) typing (for methicillin-resistant S. aureus [MRSA] isolates). Furthermore, all isolates were tested for the presence of 19 selected virulence genes.Results A total of 191 non-repetitive S. aureus clinical isolates were collected and the agr type I was the most prevalent (84.8%). S. aureus isolates were divided into 33 sequence types (STs), 20 clonal complexes (CCs) and 59 spa types, ST59 (39.8%) and t437 (37.7%) were the predominant types. CC59, CC25, CC22, CC951, CC8, and CC398 isolates possessed agr group I; CC15 isolates harbored agr group II; CC30 strains were characterized as agr group III, and CC121 harbored agr group IV. Of the 19 virulence genes, the tst gene was more prevalent among agr group III compared to other groups ( p = 0.006); eta and etb genes were more prevalent among agr group IV than other groups ( p = 0.003 and 0.001, respectively); nearly all strains that harbored the lukS/F-PV gene (98.3%) belonged to agr group I ( p = 0.004); the frequencies of bbp and ebpS genes belonged to agr group I were statistically lower than that of other groups ( p < 0.001). Among 161 diagnoses, the frequency of strains from cellulitis patient harbored agr group III was higher than that of other groups ( p = 0.046), and one strain isolated from staphylococcal scalded skin syndrome (SSSS) patient, which was identified as agr type IV ( p = 0.021).Conclusions The results indicated that the S. aureus agr type was linked to the genetic background. Besides, a possible relationship between the agr group, several virulence determinants, and specific disease types was observed.

目的 了解首都医科大学附属北京儿童医院住院患儿肺炎链球菌分离株的血清型分布和耐药性,以指导临床合理用药.方法 采用荚膜肿胀试验对首次分离的肺炎链球菌进行血清型分型,用纸片法和BD Phoenix 100全自动微生物仪进行药敏试验.结果 2013年3月-2019年2月共收集非重复肺炎链球菌834株,主要分离自3岁以下患儿(612株,73.4％).患儿以肺部感染为主(739例,88.6％).834株肺炎链球菌中分离自脑脊液菌株19株;侵袭性菌株和非侵袭性菌株分别为90株和744株.共检出43种血清型,常见的血清型为19F、19A、23F、14、6A、6B.青霉素敏感株(PSSP) 354株(42.4％),青霉素不敏感株(PNSP) 480株(57.6％);未发现利奈唑胺和万古霉素耐药株.肺炎链球菌对莫西沙星、左氧氟沙星和氯霉素的敏感率高(＞95％);但对红霉素、克林霉素和四环素的耐药率高(＞94％).侵袭性菌株和非侵袭性菌株对抗菌药物的耐药率差异无统计学意义.血清型为19F和19A的菌株对多种抗菌药物的耐药率明显高于其他血清型菌株.PNSP对多种抗菌药物的耐药率高于PSSP.结论 该院住院患儿感染肺炎链球菌血清型以19F、19A、23F、14、6A、6B为主,对莫西沙星、左氧氟沙星和氯霉素的耐药率低,对红霉素、克林霉素和四环素的耐药率高.血清型19F和19A的菌株对抗菌药物的耐药率高于其他血清型菌株.应加强细菌耐药性监测,根据患儿感染细菌的血清型和药敏试验结果合理选用抗菌药物.

Objective:To investigate the distribution of fungal species and their sensitivity to antifungal drugs in children with invasive fungal infections.Methods:All the fungal strains primarily isolated from the sterile parts of children in Beijing Children′s Hospital, Capital Medical University from January 2010 to December 2016 were analyzed.The sensitivity of strains to 5-Fluorocytosine, Fluconazole, Amphotericin B, Itraconazole and Voriconazole was tested using ATB-FUNGUS 3 yeast drug sensitivity test strip in accordance with the standards of Clinical and Laboratory Standards Institute M27-A2.Statistical analysis of data was performed using WHONET 5.6 software.Results:Among 236 fungi isolated from aseptic samples, 64.0% (151 strains) were from blood, 22.9%(54 strains) from cerebrospinal fluid, 3.8%(9 strains) from bone marrow, 3.8%(9 strains) from ascites, 3.4%(8 strains) from pleural effusion and 2.1%(5 strains) from tissues.The top 3 dominant species detected in the 236 strains of fungi were Candida spp.(175 strains, 74.2%), Cryptococcus neoformans (31 strains, 13.1%), and Saccharomyces spp.(9 strains, 3.8%). Among the Candida spp., the main isolates were Candida albicans (107 strains, 61.1%), Candida parapsilosis (33 isolates, 18.9%), and Candida tropicalis (13 isolates, 7.4%). Rare fungi of Penicillium marneffei, Exophiala spp.and Rhizopys spp.were also detected. Candida spp.was 100% sensitive to Amphotericin B. Cryptococcus neoformans was 100% sensitive to Fluconazole, Voliconazole and Amphotericin B. Conclusions:The most common strain isolated from pediatric patients with invasive fungal infections is Candida spp., especially Candida albicans. Cryptococcus neoformans causes central nervous system and systemic disseminated infections that can′t be ignored.Amphotericin B has higher antibacterial activity against Candida spp.and Cryptococcus neoformans.Separation of species of invasive fungal infections and monitoring of drug resistance in children should be strengthened to effectively control invasive fungal infections and facilitate rational use of antifungal drugs.

Staphylococcus aureus (S. aureus) with accessory gene regulator (agr) dysfunction occurs in health care settings. This study evaluated the prevalence and the molecular and drug resistance characteristics of S. aureus with dysfunctional agr in a pediatric population in Beijing, China. A total of 269 nonduplicate S. aureus clinical isolates were isolated from Beijing Children’s Hospital, including 211 methicillin-resistant S. aureus (MRSA) from September 2010–2017 and 58 methicillin-sensitive S. aureus (MSSA) from February 2016–2017. Only 8 MRSA and 2 MSSA isolates were identified as agr dysfunction, and the overall prevalence rate was 3.7%. For MRSA isolates, ST59-SCCmec IV and ST239-SCCmec III were the most common clones, and the prevalence rate of agr dysfunction in ST239-SCCmec III isolates (17.39%) was significantly higher than in ST59-SCCmec IV (1.69%) and other genotype strains (P = 0.006). Among the agr dysfunctional isolates, only one MRSA ST59 isolate and one MSSA ST22 isolate harbored pvl. No significant difference was detected between agr dysfunction and agr functional isolates regarding the biofilm formation ability (P = 0.4972); however, 9/10 agr dysfunctional isolates could effectuate strong biofilm formation and multidrug resistance. Among MRSA, the non-susceptibility rates to ciprofloxacin, gentamicin, and trimethoprim-sulfamethoxazole were significantly higher in agr dysfunctional isolates than in isolates with functional agr (P < 0.05). Two isolates belonging to ST239 had no mutations in agr locus, but a synonymous mutation was found in agrA in another ST239 isolate. The inactivating mutations were detected in other seven agr dysfunctional isolates. The variants were characterized by non-synonymous changes (n = 5) and frameshift mutations (insertions, n = 2), which mainly occurred in agrC and agrA. The results showed that agr dysfunctional S. aureus was not common in Chinese children, and ST59-SCCmec IV was associated with lower prevalence of agr dysfunction as compared to ST239-SCCmec III isolates. The agr dysfunctional isolates were healthcare-associated, multidrug resistant and form strong biofilm, which suggested that agr dysfunction might offer potential advantages for S. aureus to survive in a medical environment.

Aims & Objectives: We aimed to evaluate the clonal and drug-resistance dynamics of (Methicillin-resistant Staphylococcus aureus) MRSA in Chinese children from 2010 to 2016. Methods Totally 170 MRSA isolates were recovered from Beijing Children’s hospital from 2010 to 2016. The genotypic characteristics of all strains were determined. Antimicrobial susceptibility testing was performed by agar dilution method except sulphamethoxazole/trimethoprim (E-test method). Panton-Valentine leukocidin (pvl) gene was detected by PCR assay. Results Eighty-four isolates were classified as Community-associated Methicillin-resistant Staphylococcus aureus (CA-MRSA). ST59-SCCmecIV-t437-agrI was the most prevalent both in CA-MRSA (47.6%) and healthcare-associated MRSA (HA-MRSA) (46.5%). ST239-SCCmecIII-t030-agrI accounted for 14.0% of total HA-MRSA isolates, which had not been determined in 2016. The prevalence of pvl was similar among CA- and HA- MRSA (p=0.0805). There were no changes in antibiotic resistance in CA-MRSA from 2010 to 2016. HA-MRSA demonstrated an overall trend of decreased resistant to tetracycline, gentamicin, ciprofloxacin, rifampin, and an increased resistant to chloramphenicol during the studied period, which were basically consistent with the difference of antibiotic resistance patterns between ST59-SCCmecIV and ST239-SCCmecIII isolates. The percentage of isolates with minimal inhibitory concentration (MIC) ≥1 mg/L increased from 45.0% in 2010–2013 to 87.1% in 2016, and meanwhile, the percentage of isolates with MIC=0.5 mg/L decreased from 55.0% (55/100) to 12.9 (p<0.0001). Conclusions ST59-SCCmecIV had spread to hospital and replaced the traditional hospital associated ST239-SCCmecIII clone, which were accompanied by changes in drug resistance. Furthermore, vancomycin MIC creep indicated that the rational use of antibiotics should be taken seriously.

Objective To investigate the distribution and antimicrobial resistance profile of the common pathogens isolated during the period from 2009 to 2015.Methods All the bacterial strains isolated from pediatric inpatients in Beijing Children's Hospital during the period from 2009 to 2015 were analyzed. Antimicrobial susceptibility was determined by disk diffusion method and Phoenix 100 Automated Microbiology System. Results were analyzed according to the guidelines of CLSI (2014) using WHONET 5.6 software.Results The total strains were 26630. The most common gram-positive isolates were Streptococcus pneumoniae,Staphylococcusaureusand coagulase-negative Staphylococcus (CNS), while the most frequently isolated gram-negative microorganisms were Klebsiella spp.,Pseudomonas aeruginosa and Escherichia coli. The prevalence of S. pneumoniae was up to 25.7 % (4101/15973) in all respiratory tract specimens. About 50.2 % of the S. pneumoniae isolates were not susceptible to penicillin. The prevalence of methicillin-resistant strains was 20.6 % in S. aureus (MRSA) and 87.8 % in coagulase negative Staphylococcus (MRCNS) on average. The prevalence of MRSA increased from 11.1 % in 2009 to 29.8 % in 2015. No S. pneumoniae or staphylococcal strains were found resistant to vancomycin or linezolid. The Enterococcus strains were still highly susceptible to vancomycin and linezolid. Overall 0.3 % of the Enterococcus faecium isolates were resistant to vancomycin. The extended-spectrum beta-lactamases (ESBLs) producing strains accounted for 71.4 % -78.1 % of E. coli and 65.1 % - 76.9 % of K. pneumoniae isolates. The carbapenem-resistant E. coli and K. pneumoniae were reported for the first time in 2010, but in 2014, the strains resistant to carbapenems had increased to more than 7 % in E. coli, and higher than 20 % in K. pneumoniae. In 2015, up to 27.7 % and 25.7 % of P. aeruginosa isolates were resistant to imipenem and meropenem, respectively, and 59.9 % of the A. baumannii isolates were resistant to imipenem and meropenem. Beta-lactamase was positive in 46.3 % of the H. influenzae isolates. Conclusions MRSA and the carbapenem-resistant strains of E. coli,K. pneumoniae and A. baumannii are still on the rise in pediatric inpatients, which poses a serious threat to clinical practice and implies the importance of strengthening infection control.

OBJECTIVE:To characterize carbapenem (CPM)-non-susceptible Klebsiella pneumoniae (K. pneumoniae) and carbape-nemase produced by these strains isolated from Beijing Children's Hospital based on a five-year surveillance.METHODS:The Minimal Inhibition Concentration values for 15 antibiotics were assessed using the Phonix100 compact system. PCR amplification and DNA sequencing were used to detect genes encoding carbapenemases. WHONET 5.6 was finally used for resistance analysis.RESULTS:In total, 179 strains of CPM-non-susceptible K. pneumoniae were isolated from January, 2010 to December, 2014. The rates of non-susceptible to imipenem and meropenem were 95.0% and 95.6%, respectively. In the 179 strains, 95 (53.1%) strains carried the blaIMP gene, and IMP-4 and IMP-8 were detected in 92 (96.8%) and 3 (3.2%) IMP-producing isolates, respectively. 65 (36.3%) strains carried the blaNDM-1 gene. 6 (3.4%) strains carried the blaKPC gene, and KPC-2 were detected in 6 KPC-producing isolates. In addition, New Delhi-Metallo-1 (NDM-1) producing isolates increased from 7.1% to 63.0% in five years and IMP-4 producing isolates decreased from 75.0% to 28.3%.CONCLUSION:High frequencies of multiple resistances to antibiotics were observed in the CPM-non-susceptible K. pneumoniae strains isolated from Beijing Children's Hospital. The production of IMP-4 and NDM-1 metallo-β-lactamases appears to be an important mechanism for CPM-non- susceptible in K. pneumoniae.

Objective To analyze the distribution and antibiotic resistance profile of Haemophilus influenzae strains isolated from children for better antibiotic use.Methods The clinical and laboratory data concerning 350 strains ofH.influenzae were collected and analyzed retrospectively from 2014 to 2015 in our hospital,including pathogen source,production of beta lactamases and antimicrobial susceptibility.Antimicrobial susceptibility testing was carried out by using disk diffusion method.The results were interpreted according to the breakpoints of the Clinical and Laboratory Standards Association (CLSI) in 2014,and analyzed using WHONET 5.6 software.Results H.influenzae infection was more common in infants and young children.The prevalence of beta lactamase was 53.1％ in H.influenzae isolates.The H.influenzae isolates showed the highest resistance rate to trimethoprimsulfamethoxazole (76.9％),but relatively high susceptible rate to ciprofloxacin (99.1％),ceftizoxime (98.9％),chloramphenicol (95.4％),tetracycline (88.3％),amoxicillin-clavulanic acid (87.7％),cefuroxime (74.9％),azithromycin (65.4％),cefaclor (56.6％) and ampicillin (46.0％).All these H.influenzae strains were susceptible to ceftriaxone and meropenem.Conclusions Beta-lactamases are highly prevalent in the H.influenzae strains isolated from children,which is the main mechanism underlying ampicillin resistance in H.influenzae.Ampicillin is therefore not appropriate for first-line treatment ofH.influenzae infections.The H.influenzae strains are highly resistant to trimethoprim-sulfamethoxazole.In addition to beta-lactams,ciprofloxacin is the most active agent against H.influenzae strains,followed by chloramphenicol.

Background: This study aimed to investigate the clinical and molecular epidemiology and biofilm formation of Staphylococcus aureus (SA) isolated from pediatricians in China. Methods: SA strains were isolated from Beijing Children's hospital from February 2016 to January 2017. Isolates were typed by multilocus sequence typing (MLST), spa and SCCmec typing (for Methicillin-resistant SA [MRSA] only). Antimicrobial susceptibility testing was performed by agar dilution method except sulphamethoxazole/trimethoprim (E-test method). Biofilm formation and biofilm associated genes were detected. Results: Totally 104 children (41 females and 63 males; median age, 5.2 months) were enrolled in this study, in which 60 patients suffered from MRSA infection. Among the 104 cases, 54.8% were categorized as community associated SA (CA-SA) infections. The children under 3 years were more likely to occur CA-SA infections compared with older ones (P = 0.0131). ST59-SCCmec IV-t437 (61.7%) was the most prevalent genotype of MRSA, and ST22-t309 (18.2%), ST5-t002 (9.1%), ST6-t701 (9.1%), ST188-t189 (9.1%) were the top four genotypes of methicillin-sensitive SA (MSSA). All the present isolates were susceptible to linezolid, vancomycin, trimethoprim-sulfamethoxazole, mupirocin, tigecyclin, fusidic acid. No erythromycin-susceptible isolate was determined, and only a few isolates (3.8%) were identified as susceptible to penicillin. Multi-drug resistant isolates were reponsible for 83.8% of the ST59-SCCmec IV-t437 isolates. The isolates with strong biofilm formation were found in 85% of MRSA and 53.2% of MSSA, and in 88.7% of ST59-SCCmec IV-t437 isolates. Biofilm formation ability varied not only between MRSA and MSSA (P = 0.0053), but also greatly among different genotypes (P < 0.0001). The prevalence of the biofilm associated genes among ST59-SCCmec IV-t437 clone was: icaA (100.0%), icaD (97.3%), fnbpA (100.0%), fnbpB (0), clfA (100%), clfB (100%), cna (2.7%), bbp (0), ebpS (88.5%), sdrC (78.4%), sdrD (5.4%), and sdrE (94.5%). Conclusions: These results indicated strong homology of the MRSA stains isolated from Chinese children, which was caused by spread of multiresistant ST59-SCCmec IV-t437 clone with strong biofilm formation ability. The MSSA strains, in contrast, were very heterogeneity, half of which could produce biofilm strongly.

[Objective] To explore the pathogenic bacteria infection of the congenital heart disease (CHD) children undergoing operation in intensive care unit of Beijing Children's Hospital from 2010-2015,provide evidence for clinical rational use of antibiotics.[Methods] The postoperative specimens of CHD patients were collected,the pathogenic bacteria from positive samples were analyzed,and the bacterial susceptibility test was carried out by MIC or K-B method in clinical isolates.The results were determined according to the criteria established by the American Association for clinical laboratory standards(CLSI).[Results] There were 309 cases of nosocomial infection in CHD patients,including 94 cases of latent heart disease with cyanosis,183 cases of cyanotic heart disease,32 cases of non cyanotic congenital heart disease.The difference in the Gram-negative bacilli infection rate was statistically significant among above three groups (x2=21.755,P＜0.05).Totally 533 strains of pathogenic bacteria were isolated from the samples of CHD patients,there were 463 strains of Gram-negative bacilli,which first three were Pseudomonas aeruginosa,klebsiella pneumonia acinetobacter Baumannii,and 43 strains of Gram-positive coccus and 27 strains of fungus.Pseudomonas aeruginosa showed higher antibacterial activity to amikacin,cefepime and piperacillin/tazobactam,and the resistance to imipenem reached 40.9％.The drug resistant rate of acinetobacter Baumannii was higher than that of the enteric bacilli,and 31 strains of multidrug-resistant bacteria were detected.Gram-negative bacilli showed high resistance rate to ampicillin and 1 and 2 generation cephalosporin.The proportion of strains of extended-spectrum β-lactamase (ESBL) producing Escherichia coli and klebsiella pneumoniae were higher than 80％.Staphylococcus had high resistance to penicillin,erythromycin and clindamycin,and the resistance rate of Staphylococcus aureus to penicillin was 100％.3 strains of methicillin-resistant Staphylococcus aureus (MRSA) and 13 trains of methicillin-resistant coagulase-negative staphylococci (MRCNS) were detected.[Conclusion] The nosocomial infection in CHD children is mainly lower respiratory tract infection,while the drug resistance and multidrug-resistant bacteria are increasing.It is necessary to take effective measures to prevent and control nosocomial infection,strengthen the drug sensitivity monitoring,and guide clinical rational use of antibiotics.

目的 研究儿童患者中分离的卡他莫拉菌临床分布及耐药性,指导临床合理用药.方法 对2013-2014年北京儿童医院临床送检标本分离出的189株卡他莫拉菌的分布、产酶情况和药敏结果进行回顾性分析.采用纸片扩散法作药敏试验,头孢硝噻吩纸片法测定β内酰胺酶.依照2013年CLSI M45-A2标准判断结果.结果 卡他莫拉菌多分离于婴幼儿患者,常混合其他细菌.β内酰胺酶阳性率为95.7％,对阿莫西林-克拉维酸、甲氧苄啶-磺胺甲(噁)唑、四环素耐药率分别为0、2.1％和4.2％.对红霉素和阿奇霉素耐药严重,耐药率达到了82.5％和83.1％.结论 儿童患者携带的卡他莫拉菌β内酰胺酶阳性率很高,其高产酶特点使青霉素类药物不能作为临床一线用药.卡他莫拉菌对大环内酯类耐药性较高,应引起临床重视,并加强对其耐药监测.