新生儿无乳链球菌感染的危险因素及药敏分析

目的分析新生儿感染无乳链球菌的危险因素及药物敏感性,为预防和治疗新生儿无乳链球菌感染提供依据。方法收集2013年1~12月1 200份临床送检的新生儿血液、胃液、脓液标本,以及相应母体泌尿生殖道标本进行细菌培养与药敏试验,并回顾性分析患儿疾病类型、母体感染状况、分娩方式、孕晚期用药情况、新生儿死亡情况等临床资料。结果共80例新生儿感染无乳链球菌,其中败血症、脐炎、早产、宫内感染、吸入性肺炎患儿分别占8.75%、10.00%、15.00%、22.50%、43.75%;其母体生殖道标本无乳链球菌阳性率达51.25%,且细菌药敏结果与患儿一致;患儿以自然分娩为主,共71例(88.75%),仅9例(11.25%)为剖宫产。80株无乳链球菌对万古霉素、利奈唑胺、青霉素和头孢曲松的敏感率均为100.00%,对红霉素、克林霉素、左氧氟沙星的耐药率较高,分别为77.50%、57.50%、33.75%。结论母体带菌与分娩方式可能是新生儿无乳链球菌感染的重要危险因素,产科医生应重视对围产期孕妇无乳链球菌的常规筛查,实验室应提高对无乳链球菌的检测能力并及时提供药敏检测结果,为临床合理用药提供重要依据。     

Enterococcal endocarditis: 107 cases from the international collaboration on endocarditis merged database

PURPOSE: To describe clinical features and outcomes of enterococcal left-sided native valve endocarditis and to compare it to endocarditis caused by other pathogens. SUBJECTS AND METHODS: Patients in the International Collaboration on Endocarditis-Merged Database were included if they had left-sided native valve endocarditis. Demographic characteristics, clinical features, and outcomes were analyzed. Multivariable analysis evaluated enterococcus as a predictor of mortality. RESULTS: Of 1285 patients with left-sided native valve endocarditis, 107 had enterococcal endocarditis. Enterococcal endocarditis was most frequently seen in elderly men, frequently involved the aortic valve, tended to produce heart failure rather than embolic events, and had relatively low short-term mortality. Compared to patients with non-enterococcal endocarditis, patients with enterococcal endocarditis had similar rates of nosocomial acquisition, heart failure, embolization, surgery, and mortality. Compared to patients with streptococcal endocarditis, patients with enterococcal endocarditis were more likely to be nosocomially acquired (9 of 59 [15%] vs 2 of 400 [1%]; P <.0001) and have heart failure (49 of 107 [46%] vs 234 of 666 [35%]; P = 0.03). Compared to patients with S. aureus endocarditis, patients with enterococcal endocarditis were less likely to embolize (28 of 107 [26%] vs 155 of 314 [49%]; P <.0001) and less likely to die (12 of 107 [11%] vs 83 of 313 [27%]; P = 0.001). Multivariable analysis of all patients with left-sided native valve endocarditis showed that enterococcal endocarditis was associated with lower mortality (odds ratio [OR] 0.49; 95% confidence interval [CI] 0.24 to 0.97). CONCLUSIONS: Enterococcal native valve endocarditis has a distinctive clinical picture with a good prognosis.     

Influence of the magnetic field on microorganisms in the oral cavity

Since the beginning of their lives, all living organisms are exposed to the influence of geomagnetic fields.

Objectives

: With respect to the positive effects that magnetic fields have on human tissues, especially the bactericidal effect, this investigation aimed to assess their influence on the reduction of oral microorganisms.

Material and Methods

: In order to obtain adequate specimens of dental plaque deposit, microbes such as Streptococcus parasanguinis, Staphylococcus epidermidis, Rhodococcus equi and Candida albicans were isolated from the human mouth. To establish the intensity of microbial growth on the basis of the modified optical density (OD) of agar turbidimetry assay, microbial count and spectrophotometry were applied. The study was carried out with two microbial concentrations (1 and 10 CFU/ml) after periods of incubation of 24 and 48 h and using micromagnets.

Results

: A positive effect of the magnetic field, resulting in the reduction of dental plaque microbes in vitro, was found. In the first 24 hours of exposure to the magnetic field, the number of all isolated microbes was significantly reduced. The most potent influence of magnets and the most intensified reduction after 24 hours were evident in Candida albicans colonies. The decrease in the influence of magnets on microbes in vitro was also detected.

Conclusions

: Magnets reduce the number of microbes and might be recommended as a supplement in therapy for reduced periodontal tissues. This is important because periodontal tissues that are in good conditions provide prolonged support to the oral tissues under partial and supradental denture.     

Bacterial colonization dynamics associated with respiratory syncytial virus during early childhood

Respiratory syncytial virus (RSV) is an important cause of early life acute respiratory infections. Potentially pathogenic respiratory bacteria, including Streptococcus pneumoniae, Moraxella catarrhalis, and Haemophilus influenzae are frequently detected during RSV infections and associated with increased illness severity. However, the temporal dynamics of bacterial colonization associated with RSV infection remain unclear. We used weekly nasal swab data from a prospective longitudinal birth cohort in Brisbane, Australia, to investigate bacterial colonization patterns within children aged less than 2 years in the 4‐week period before and after an RSV infection. During 54 RSV infection episodes recorded in 47 children, both S. pneumoniae and M. catarrhalis were detected frequently (in 33 [61.1%] and 26 [48.1%] RSV infections, respectively). In most cases, S. pneumoniae and M. catarrhalis colonization preceded the viral infection, with the nasal load of each increasing during RSV infection. Generally, the dominant serotype of S. pneumoniae remained consistent in the 1 to 2 weeks immediately before and after RSV infection. Little evidence was found to indicate that prior colonization with either bacteria predisposed participants to developing RSV infection during the annual seasonal epidemic. Possible coacquisition events, where the bacteria species was first detected with RSV and not in the preceding 4 weeks, were observed in approximately 20% of RSV/S. pneumoniae and RSV/M. catarrhalis codetections. Taken together our results indicate that RSV generally triggered an outgrowth, rather than a new acquisition, of S. pneumoniae and M. catarrhalis from the resident microbial community.     

Bloodstream infection by multidrug‐resistant Streptococcus oralis in a leukemic patient with febrile neutropenia after hematopoietic stem cell transplantation

We reported the case of a patient with leukemia who developed febrile neutropenia after hematopoietic stem cell transplantation. Blood culture results revealed the presence of Streptococcus oralis, while antimicrobial susceptibility testing showed the resistance to penicillin and cephem. Furthermore, isolates were not susceptible to either meropenem or daptomycin but not to vancomycin. S oralis is known to belong to Streptococcus mitis group and be a causative agent of bacteremia in the neutropenic patients, but multidrug resistance of S oralis is rare. Our findings suggest that we might pay attention to the emergence of the microorganisms acquiring multidrug resistance in neutropenic patients.     

A C-terminal truncated mutation of licC attenuates the virulence of Streptococcus pneumoniae

LicC has been identified as a virulence factor of Streptococcus pneumoniae. However, its role in virulence is still not fully understood because deletion of licC is lethal for the bacterium. In this study, a mutant with 78-bp truncation at the C-terminus of licC was obtained from a signature-tagged mutagenesis (STM) library. The mutant was viable with a large reduction in enzymatic activity as CTP:phosphocholine cytidylyltransferase detected in vitro using a firefly luciferase assay. The mutation attenuated the adhesion and invasion of S. pneumoniae ST556 (serotype 19F) to epithelial cells by 72% and 80%, respectively, and increased the phagocytosis by macrophages for 16.5%, compared to the parental strain. When the mutation was introduced into the encapsulated D39 strain (serotype 2), it led to attenuated virulence in mouse models either by intranasal colonization or by intraperitoneal infection. In addition, the phosphocholine (PCho) on cell surface was decreased, and the choline binding proteins (CBPs) were impaired, which may explain the attenuated virulence of the mutant. These observations indicate that C-terminus of licC is accounted for the main activity of LicC in PCho metabolism and is essential for the virulence of S. pneumoniae, which provides a novel target for drug design against pneumococcal infection.     

晚期妊娠孕妇B群链球菌定植状况及妊娠结局分析

目的探讨妊娠晚期孕妇B群链球菌（GBS）定植情况、抗菌药物敏感性及妊娠结局。方法纳入2016年1月至2018年12月在东部战区总医院和南京医科大学第一附属医院妇产科定期产检的孕妇，于孕35~37周采用标准方法采集阴道及直肠拭子进行GBS培养，并对阳性标本分离的菌株进行药物敏感性试验。按培养结果分为GBS阳性组和GBS阴性组，阳性组按照产程中是否使用了抗菌药物治疗分为用药组与未用药组，比较不同组别妊娠结局的差异。结果共13 000名孕妇入组，GBS总体定植率为3.65%（475/13 000）。GBS在阴道中定植率为2.33%（303/13 000），在直肠中定植率为1.75%（227/13 000）。通过对直肠标本的采集检测，GBS阳性检出率增加了56.77%（172/303）。GBS每月的定植率有明显波动，3月份和10月份最高（均 P < 0.05）。475份GBS阳性标本对头孢曲松、万古霉素和利奈唑胺的敏感率为100%，对氨苄西林和青霉素的敏感率分别为97.26%和93.47%，而对左氧氟沙星、克林霉素、红霉素、四环素的耐药率较高，分别为30.11%、48.00%、52.21%和88.63%。GBS阳性组胎膜早破、产后出血、产褥期感染、新生儿肺炎、败血症发生率较GBS阴性组明显增高（均 P < 0.01）。产程中预防性使用抗菌药物的GBS阳性孕妇产褥期感染、新生儿感染及新生儿重症监护室入住率明显低于未使用抗菌药物的孕妇（ P < 0.05或 P < 0.01）。 结论妊娠晚期孕妇GBS定植率较低，无明显的季节性，通过补充直肠检测能提高GBS检出率。头孢曲松、氨苄西林和青霉素是目前预防和治疗GBS相关疾病的首选药物。GBS感染会明显增加母婴并发症的发生可能，产程中抗菌药物治疗可以改善母婴的结局。