A comprehensive approach to ending an outbreak of rare blaOXA-72 gene-positive carbapenem-resistant Acinetobacter baumannii at a Community Hospital,Kansas City,MO, 2018

We identified a cluster of extensively drug-resistant, carbapenemase gene-positive, carbapenem-resistant Acinetobacter baumannii (CP-CRAB) at a teaching hospital in Kansas City. Extensively drug-resistant CRAB was identified from eight patients and 3% of environmental cultures. We used patient cohorting and targeted environmental disinfection to stop transmission. After implementation of these measures, no additional cases were identified.     

我国艰难梭菌流行特征和研究进展

艰难梭菌被认为是抗生素和医疗机构相关性腹泻的主要病原,被美国疾病预防控制中心列为抗生素相关的紧迫公共卫生威胁之一。 近10年来,我国艰难梭菌感染的发生率显著上升,艰难梭菌的研究也日益深入,本研究旨在结合已有报道和研究成果,对我国艰难梭菌的流行特征进行总结,并展望领域内的热点问题,以期对未来研究提供参考。     

Epidemiological investigation of an outbreak of pandemic influenza A (H1N1) 2009 in a boarding school: Serological analysis of 1570 cases

BackgroundA large number of 2009 pandemic influenza A (H1N1) infections were localized in school populations.ObjectivesTo describe the epidemiology, clinical features and risk factors associated with an outbreak that occurred at a vocational boarding school in Guangzhou, P.R. China.Study designData were collected prospectively and retrospectively through the use of on-site doctors and a post-outbreak survey and blood collection. The survey was used to confirm symptoms, and to investigate a series of flu-related factors such as dormitory conditions, health habits, vaccine history and population contact history. Blood samples were taken for serological analysis. Pandemic H1N1 infection was initially confirmed by a real-time RT-PCR assay. Following the identification of the outbreak by the Guangzhou CDC on September 4, cases were diagnosed symptomatically and retrospectively by serological analysis using the hemagglutination inhibition assay and a neutralization assay.ResultsThe infection rate was 32% (505/1570) and the attack rate was 22.2% (349/1570). The asymptomatic infection rate was 9.9% (156/1570). Sharing a classroom (OR = 2.17, 95% CI: 1.62–2.91) and dormitory space (OR = 2.32, 95% CI: 1.84–2.93) was associated with higher rates of infection. Opening windows for ventilation was the only control measure that significantly protected against infection.ConclusionSocial isolation and quarantine should be used to prevent the spread of infection. Ventilation and a control of air flow between classrooms and dorms should be implemented as possible. School closures may be effective if implemented early.     

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.     

Resequencing microarray method for molecular diagnosis of human arboviral diseases

BackgroundResequencing DNA microarray (RMA) technology uses probes designed to identify a panel of viral sequences. It can be used for detecting emerging viruses by revealing the nucleotide polymorphisms within the target of interest.Objectives/study designAs a new tool for molecular diagnosis of arbovirus infection, high density PathogenID v2.0 RMA (PID2-RMA) was assessed for the detection and genetic analysis of dengue, West Nile, and Chikungunya viruses in spiked blood samples or sera from individuals infected with dengue virus. Viral RNAs extracted from biological samples were retrotranscribed into cDNA and amplified using the Phi 29 polymerase-based method. This amplified cDNA was used for hybridization on PID2-RMA.ResultsA good specificity of RMA-based detection was demonstrated using a panel of arboviruses including Dengue, West Nile and Chikungunya viruses. This technology was also efficient for the detection and genetic analysis of the different serotypes of dengue virus in sera of infected patients. Furthermore, the mixing of dengue, West Nile and Chikungunya prototype viruses within a single sample of human blood did not interfere with the sensitivity of PID2-RMA.ConclusionsOur data show that high density PID2-RMA was suitable for the identification of medically important arboviruses. It appears to be particularly adapted to the genetic analysis of dengue, West Nile, and Chikungunya viruses in urgent clinical situations where the rapid identification and characterization of the pathogen is essential.     

Magnetic-silica based nucleic acid extraction for Human Immunodeficiency Virus Type-1 drug-resistance testing in low viremic patients

Human Immunodeficiency Virus Type-1 (HIV-1) drug-resistance testing is challenging for viral loads below 1,000 copies/mL, but, according to HIV-1 guidelines, it should be considered for improving patient management and treatment options. High-recovery and high-purity extraction methods can enhance standard performances of HIV-1 genotyping assays based on direct full-population sequencing.Aim of the present study was to evaluate performances of the NucliSENS easyMAG (NeM) (BioMerieux, Marcy l’Etoile, F) semi-automated nucleic acid extraction system combined with the direct full-population sequencing ViroSeq HIV-1 genotyping (Abbott, IL, US), for detecting drug resistance in samples with HIV-1 RNA < 1,000 copies/mL (n = 62). Data were compared with those from the ViroSeq manual extraction in 86 samples with HIV-1 RNA < 1,000 copies/mL and studied on HIV-1 reference standards.HIV-1 genotyping was successful in 98% of samples extracted with NeM (61/62) and in 84% of those extracted with ViroSeq (72/86) (X² = 8.508, p = 0.004). HIV-1 RNA levels in samples successfully processed with NeM were significantly lower than those in manually processed ones (mean ± SD, respectively, 285 ± 222 copies/mL vs. 403 ± 269 copies/mL) (p = 0.004). For HIV-1 RNA levels <300 and 500 copies/mL, performances of HIV-1 genotyping with NeM were significantly high (97% and 98%, vs. 68% and 78% for manual extraction). As assessed on HIV-1 RNA reference standards, the detection rate at 200 copies/mL for HIV-1 genotyping with NeM extraction was 100%.In conclusion, these data support that HIV-1 direct full-population sequencing combined with NeM is associated with a significantly high success rate, thus improving the management of HIV-1 drug resistance in low viremic patients.