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1.
Artigo em Inglês | MEDLINE | ID: mdl-31493529

RESUMO

OBJECTIVES: This study evaluated disc diffusion tests and agar screening for detection of mecA-mediated oxacillin resistance in Staphylococcus lugdunensis. METHODS: S. lugdunensis isolates (n = 179) from diverse sources in Hong Kong, 1998-2018 were investigated by disc diffusion tests (cefoxitin and oxacillin) and inoculation onto oxacillin (1 µg/ml and 2 µg/ml) and chromID MRSA agars. The results were compared with mecA PCR as the reference. Isolates with discordant results were further tested by MIC and penicillin binding protein 2a (PBP2a) assays. RESULTS: Cefoxitin and oxacillin zone diameters were not distributed in ways that allowed reliable division of the mecA-positive (n = 52) and mecA-negative (n = 127) isolates. On applying the 2019 Clinical Laboratory Standards Institute M100 breakpoints for cefoxitin disc results, there was 88% categorical agreement (CA) and 40% very major errors (VMEs). Screening using 2 µg/ml oxacillin agar reliably differentiated mecA-positive and mecA-negative isolates (100% CA) without any major error (ME) or VME results. The performance of screening using 1 µg/ml oxacillin agar or ChromID MRSA agar was variable (74%-89% CA, 0-38% MEs and 0-37% VMEs). The mecA-positive isolates (n = 21) that could not be detected by the cefoxitin disc test were further characterized. Cefoxitin MIC for all 21 isolates were ≤4 µg/ml. Twenty isolates had oxacillin MIC of 1-2 µg/ml and one had oxacillin MIC of 4 µg/ml. All had positive PBP2a results and were typed as clonal cluster (CC) 27/SCCmec V. CONCLUSIONS: Our findings highlight the need to evaluate phenotypic methods using mecA positive S. lugdunensis with different oxacillin resistance phenotypes.

2.
J Med Microbiol ; 68(9): 1367-1372, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31329093

RESUMO

Methicillin-resistant Staphylococcus lugdunensis (MRSL) is increasingly recognized in healthcare and community settings. To obtain a better understanding of the emergence of MRSL, this study characterized the structure and content of the SCCmec elements harboured by 36 MRSL isolates obtained from diverse sources in Hong Kong from 2008 to 2017. The isolates were investigated by whole-genome sequencing. SCCmec types and subtypes were assigned according to the guidelines from the International Working Group on the Classification of Staphylococcal Cassette Chromosome Elements. The sequence type (ST)-SCCmec combinations in the 36 MRSL isolates were as follows: ST3-SCCmec IV (n=2), ST3-SCCmec V (n=28), ST27-SCCmec V (n=5) and ST42-SCCmec V (n=1). The two SCCmec IV elements were highly similar to the SCCmec IV element harboured by the community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) strain, JCSC6668. The J3-mec complex-J2 regions in the SCCmec V elements were highly similar to the corresponding regions in the CA-MRSA strains PM1 (n=13) or WIS (n=21). Based on the J1 to J3 sequences, the SCCmec V elements can be categorized into nine different subtypes. Our findings highlight the diversified structures of SCCmec elements among MRSL strains and their close relationship with SCCmec elements harboured by CA-MRSA.


Assuntos
Cromossomos Bacterianos/genética , Infecções Comunitárias Adquiridas/microbiologia , Genes Bacterianos/genética , Staphylococcus aureus Resistente à Meticilina/genética , Infecções Estafilocócicas/microbiologia , Staphylococcus lugdunensis/genética , Antibacterianos/farmacologia , Infecções Comunitárias Adquiridas/epidemiologia , DNA Bacteriano/genética , Genoma Bacteriano/genética , Hong Kong/epidemiologia , Humanos , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/efeitos dos fármacos , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Testes de Sensibilidade Microbiana , Epidemiologia Molecular , Análise de Sequência de DNA , Infecções Estafilocócicas/epidemiologia , Estudantes de Medicina
3.
Gigascience ; 8(7)2019 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-31289833

RESUMO

BACKGROUND: Optical mapping is an emerging technology that complements sequencing-based methods in genome analysis. It is widely used in improving genome assemblies and detecting structural variations by providing information over much longer (up to 1 Mb) reads. Current standards in optical mapping analysis involve assembling optical maps into contigs and aligning them to a reference, which is limited to pairwise comparison and becomes bias-prone when analyzing multiple samples. FINDINGS: We present a new method, OMMA, that extends optical mapping to the study of complex genomic features by simultaneously interrogating optical maps across many samples in a reference-independent manner. OMMA captures and characterizes complex genomic features, e.g., multiple haplotypes, copy number variations, and subtelomeric structures when applied to 154 human samples across the 26 populations sequenced in the 1000 Genomes Project. For small genomes such as pathogenic bacteria, OMMA accurately reconstructs the phylogenomic relationships and identifies functional elements across 21 Acinetobacter baumannii strains. CONCLUSIONS: With the increasing data throughput of optical mapping system, the use of this technology in comparative genome analysis across many samples will become feasible. OMMA is a timely solution that can address such computational need. The OMMA software is available at https://github.com/TF-Chan-Lab/OMTools.

4.
J Clin Microbiol ; 57(8)2019 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-31189582

RESUMO

An in-house-developed pncA sequencing assay for analysis of pyrazinamide (PZA) resistance was evaluated using 162 archived Mycobacterium tuberculosis complex (MTBC) isolates with phenotypic PZA susceptibility profiles that were well defined by analysis of Bactec MGIT 960 PZA kit and PZase activity data. Preliminary results showed 100% concordance between pncA sequencing and phenotypic PZA drug susceptibility test (DST) results among archived isolates. Also, 637 respiratory specimens were prospectively collected, and 158 were reported as MTBC positive by the Abbott Realtime MTB assay (96.3% sensitivity [95% confidence interval {CI}: 92.2% to 98.7%]; 100% specificity [95% CI: 99.2% to 100.0%]). Genotypic and phenotypic PZA resistance profiles of these 158 MTBC-positive specimens were analyzed by pncA sequencing and Bactec MGIT 960 PZA kit, respectively. For analysis of PZA resistance, pncA sequencing detected pncA mutations in 5/5 (100%) phenotypic PZA-resistant respiratory specimens within 4 working days. No pncA mutations were detected among PZA-susceptible specimens. Combining archived isolates with prospective specimens, 27 were identified as phenotypic PZA resistant with pncA mutation. Among these 27 samples, 6/27 (22.2%) phenotypic PZA-resistant strains carried novel pncA mutations without rpsA and panD mutations. These included 5 with mutations (a deletion [Del] at 383T [Del383T], Del 380 to 390, insertion of A [A Ins] at position 127, A Ins at position 407, and G Ins at position 508) in pncA structural genes and 1 with a mutation (T-12C) at the pncA promoter region. All six of these strains had no or reduced PZase activities, indicating that the novel mutations might confer PZA resistance. Additionally, 25/27 phenotypic PZA-resistant strains were confirmed multidrug-resistant tuberculosis (MDR-TB) strains. As PZA is commonly used in MDR-TB treatment regimens, direct pncA sequencing will rapidly detect PZA resistance and facilitate judicious use of PZA in treating PZA-susceptible MDR-TB.

5.
Lancet Infect Dis ; 19(7): 759-769, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31196809

RESUMO

BACKGROUND: Invasive pneumococcal disease remains an important health priority owing to increasing disease incidence caused by pneumococci expressing non-vaccine serotypes. We previously defined 621 Global Pneumococcal Sequence Clusters (GPSCs) by analysing 20 027 pneumococcal isolates collected worldwide and from previously published genomic data. In this study, we aimed to investigate the pneumococcal lineages behind the predominant serotypes, the mechanism of serotype replacement in disease, as well as the major pneumococcal lineages contributing to invasive pneumococcal disease in the post-vaccine era and their antibiotic resistant traits. METHODS: We whole-genome sequenced 3233 invasive pneumococcal disease isolates from laboratory-based surveillance programmes in Hong Kong (n=78), Israel (n=701), Malawi (n=226), South Africa (n=1351), The Gambia (n=203), and the USA (n=674). The genomes represented pneumococci from before and after pneumococcal conjugate vaccine (PCV) introductions and were from children younger than 3 years. We identified predominant serotypes by prevalence and their major contributing lineages in each country, and assessed any serotype replacement by comparing the incidence rate between the pre-PCV and PCV periods for Israel, South Africa, and the USA. We defined the status of a lineage as vaccine-type GPSC (≥50% 13-valent PCV [PCV13] serotypes) or non-vaccine-type GPSC (>50% non-PCV13 serotypes) on the basis of its initial serotype composition detected in the earliest vaccine period to measure their individual contribution toward serotype replacement in each country. Major pneumococcal lineages in the PCV period were identified by pooled incidence rate using a random effects model. FINDINGS: The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. The five most prevalent serotypes in the PCV13 period varied between countries, with only serotypes 5, 12F, 15B/C, 19A, 33F, and 35B/D common to two or more countries. These serotypes were associated with more than one lineage, except for serotype 5 (GPSC8). Serotype replacement was mainly mediated by expansion of non-vaccine serotypes within vaccine-type GPSCs and, to a lesser extent, by increases in non-vaccine-type GPSCs. A globally spreading lineage, GPSC3, expressing invasive serotypes 8 in South Africa and 33F in the USA and Israel, was the most common lineage causing non-vaccine serotype invasive pneumococcal disease in the PCV13 period. We observed that same prevalent non-vaccine serotypes could be associated with distinctive lineages in different countries, which exhibited dissimilar antibiotic resistance profiles. In non-vaccine serotype isolates, we detected significant increases in the prevalence of resistance to penicillin (52 [21%] of 249 vs 169 [29%] of 575, p=0·0016) and erythromycin (three [1%] of 249 vs 65 [11%] of 575, p=0·0031) in the PCV13 period compared with the pre-PCV period. INTERPRETATION: Globally spreading lineages expressing invasive serotypes have an important role in serotype replacement, and emerging non-vaccine serotypes associated with different pneumococcal lineages in different countries might be explained by local antibiotic-selective pressures. Continued genomic surveillance of the dynamics of the pneumococcal population with increased geographical representation in the post-vaccine period will generate further knowledge for optimising future vaccine design. FUNDING: Bill & Melinda Gates Foundation, Wellcome Sanger Institute, and the US Centers for Disease Control.

6.
Int J Med Microbiol ; 309(5): 270-273, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31113737

RESUMO

In 2017, we identified a Clostridium difficile strain HKCD4 that caused community-acquired fulminant colitis in a previously healthy child. Phylogenetically, it belonged to clade 2, sequence type 67 and was resistant to fluoroquinolone and tetracycline. The strain was pathogenicity locus and binary toxin positive. It has a mutation in the trehalose repressor treR leading to the L172I substitution that was previously reported in the epidemic ribotype 027 lineage. HKCD4 has a tcdB sequence that shared very high identities with 3 highly virulent reference strains. It has a CpG depleted genome that is characteristic of hypervirulent C. difficile. The emergence of ST67 lineage with molecular feature of hypervirulence in the community is concerning and emphasizes the need for full characterization of strains causing severe disease in patients without classical risk factors.


Assuntos
Clostridium difficile/genética , Clostridium difficile/patogenicidade , Colite/microbiologia , Infecção Hospitalar/microbiologia , Genoma Bacteriano , Proteínas de Bactérias/genética , Criança , Infecções por Clostridium/diagnóstico , Infecções por Clostridium/microbiologia , Colo/diagnóstico por imagem , Colo/microbiologia , Feminino , Genômica , Hong Kong , Humanos , Ribotipagem , Tomografia Computadorizada por Raios X , Virulência
7.
EBioMedicine ; 43: 338-346, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31003929

RESUMO

BACKGROUND: Pneumococcal conjugate vaccines have reduced the incidence of invasive pneumococcal disease, caused by vaccine serotypes, but non-vaccine-serotypes remain a concern. We used whole genome sequencing to study pneumococcal serotype, antibiotic resistance and invasiveness, in the context of genetic background. METHODS: Our dataset of 13,454 genomes, combined with four published genomic datasets, represented Africa (40%), Asia (25%), Europe (19%), North America (12%), and South America (5%). These 20,027 pneumococcal genomes were clustered into lineages using PopPUNK, and named Global Pneumococcal Sequence Clusters (GPSCs). From our dataset, we additionally derived serotype and sequence type, and predicted antibiotic sensitivity. We then measured invasiveness using odds ratios that relating prevalence in invasive pneumococcal disease to carriage. FINDINGS: The combined collections (n = 20,027) were clustered into 621 GPSCs. Thirty-five GPSCs observed in our dataset were represented by >100 isolates, and subsequently classed as dominant-GPSCs. In 22/35 (63%) of dominant-GPSCs both non-vaccine serotypes and vaccine serotypes were observed in the years up until, and including, the first year of pneumococcal conjugate vaccine introduction. Penicillin and multidrug resistance were higher (p < .05) in a subset dominant-GPSCs (14/35, 9/35 respectively), and resistance to an increasing number of antibiotic classes was associated with increased recombination (R2 = 0.27 p < .0001). In 28/35 dominant-GPSCs, the country of isolation was a significant predictor (p < .05) of its antibiogram (mean misclassification error 0.28, SD ±â€¯0.13). We detected increased invasiveness of six genetic backgrounds, when compared to other genetic backgrounds expressing the same serotype. Up to 1.6-fold changes in invasiveness odds ratio were observed. INTERPRETATION: We define GPSCs that can be assigned to any pneumococcal genomic dataset, to aid international comparisons. Existing non-vaccine-serotypes in most GPSCs preclude the removal of these lineages by pneumococcal conjugate vaccines; leaving potential for serotype replacement. A subset of GPSCs have increased resistance, and/or serotype-independent invasiveness.


Assuntos
Farmacorresistência Bacteriana , Genoma Bacteriano , Genômica , Infecções Pneumocócicas/microbiologia , Streptococcus pneumoniae/classificação , Streptococcus pneumoniae/genética , Antibacterianos/farmacologia , Antibacterianos/uso terapêutico , Biodiversidade , Evolução Molecular , Feminino , Genômica/métodos , Genótipo , Saúde Global , Humanos , Masculino , Infecções Pneumocócicas/tratamento farmacológico , Infecções Pneumocócicas/epidemiologia , Infecções Pneumocócicas/prevenção & controle , Vacinas Pneumocócicas , Polimorfismo de Nucleotídeo Único , Sorogrupo , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/imunologia
8.
J Orthop Surg (Hong Kong) ; 27(1): 2309499019825587, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-30798715

RESUMO

Infection is one of the commonest causes for megaprosthesis failure. The current treatment includes antibiotics but no surgery, debridement, prosthesis removal and joint fusion, prosthesis revision or amputation. Success in controlling infection may be less than 50% in implant revision. The overall risk of amputation is more than 20%. We believe that repeated debridement with antibiotic-laden cement wrap (ALCW) may be a reliable alternative for managing the megaprosthesis infection. The purposes of this article are to identify whether ALCW is an effective way of eradicating the megaprosthesis infection, the associated complications and the functional outcome after management by ALCW. METHODS: This was a retrospective study of patients with megaprosthesis infection. From January 2014 to June 2016, there were five patients with tumour megaprosthesis infection who had undergone the ALCW procedure. Ages ranged from 17 to 59 years of age. Male to female ratio was 4:1. The patients studied had humeral (1), proximal femoral (1), distal femoral (1) and proximal tibial (2) prostheses. All patients had follow-ups more than 1 year (21-52 months) after treatment. RESULTS: All patients recovered from their implant infection and the implants were retained in all patients. There was no sign of infection in the most recent follow-up. One patient died of osteosarcoma recurrence. One patient had a large block of cement causing plastic insert dislodgement in the shoulder joint 1 year after surgery. Another patient with a dislocated hip cup had revision carried out in the final debridement. The most recent Musculoskeletal Tumor society (MSTS) scores ranged from 21 to 30. All patients were satisfied with their treatment. CONCLUSIONS: In this preliminary report of a small number of patients, ALCW has achieved 100% infection control. ALCW may be an easy and effective alternative for managing the megasprosthesis infection. The complications associated can be avoidable. The functional outcome is excellent.

9.
Eur J Clin Microbiol Infect Dis ; 38(3): 563-573, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30680562

RESUMO

We describe a nosocomial outbreak of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) ST59-SCCmec type V in a neonatal intensive care unit (NICU) in Hong Kong. In-depth epidemiological analysis was performed by whole-genome sequencing (WGS) of the CA-MRSA isolates collected from patients and environment during weekly surveillance and healthcare workers from the later phase of the outbreak. Case-control analysis was performed to analyze potential risk factors for the outbreak. The outbreak occurred from September 2017 to February 2018 involving 15 neonates and one healthcare worker. WGS analysis revealed complicated transmission dynamics between patients, healthcare worker, and environment, from an unrecognized source introduced into the NICU within 6 months before the outbreak. In addition to enforcement of directly observed hand hygiene, environmental disinfection, cohort nursing of colonized and infected patients, together with contact tracing for secondary patients, medical, nursing, and supporting staff were segregated where one team would care for CA-MRSA-confirmed/CA-MRSA-exposed patients and the other for newly admitted patients in the NICU only. Case-control analysis revealed use of cephalosporins [odds ratio 49.84 (3.10-801.46), p = 0.006] and length of hospitalization [odds ratio 1.02 (1.00-1.04), p = 0.013] as significant risk factors for nosocomial acquisition of CA-MRSA in NICU using multivariate analysis. WGS facilitates the understanding of transmission dynamics of an outbreak, providing insights for outbreak prevention.


Assuntos
Infecção Hospitalar/epidemiologia , Surtos de Doenças , Controle de Infecções/métodos , Unidades de Terapia Intensiva Neonatal , Staphylococcus aureus Resistente à Meticilina/isolamento & purificação , Infecções Estafilocócicas/epidemiologia , Técnicas de Tipagem Bacteriana , Estudos de Casos e Controles , Infecção Hospitalar/microbiologia , Infecção Hospitalar/transmissão , Surtos de Doenças/prevenção & controle , Microbiologia Ambiental , Feminino , Pessoal de Saúde , Hong Kong/epidemiologia , Humanos , Recém-Nascido , Masculino , Staphylococcus aureus Resistente à Meticilina/classificação , Staphylococcus aureus Resistente à Meticilina/genética , Fatores de Risco , Infecções Estafilocócicas/microbiologia , Infecções Estafilocócicas/transmissão , Sequenciamento Completo do Genoma
11.
Front Microbiol ; 9: 2272, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30294321

RESUMO

The emergence of New Delhi metallo-ß-lactamase (NDM) in common enterobacterial species is a major concern for healthcare. Early reports have revealed that the spread of NDM involved diverse and heterogeneous plasmids. Recently, the involvement of a rare, IncX3 subtype plasmid has been increasingly recognized. Here, we studied the prevalence of IncX plasmid subtypes in 198 carbapenem-resistant Enterobacteriaceae, originating from a territory-wide active surveillance in Hong Kong in 2016. The complete sequences and biological features of the bla NDM-carrying plasmids were investigated. A total of 62 NDM-type, 21 OXA-48 type, 14 IMP-type, 8 KPC-type, 4 IMI-type producers, and 89 non-carbapenemase-producers were tested for presence of IncX subtypes. IncX3 (n = 60) was the most common subtype, followed by IncX4 (n = 6) and IncX1 (n = 2). The prevalence of IncX3 subtype in isolates producing NDM, other carbapenemase types and non-carbapenemase producers were 75.8, 21.3, and 3.4%, respectively (P < 0.001). An IncX3 plasmid (size ∼50 kb) was confirmed to carry bla NDM in 47 isolates of different enterobacterial species. Thirteen IncX3 plasmids originating from six healthcare regions in Hong Kong were completely sequenced. The results showed that the IncX3 plasmids carrying bla NDM share a high degree of sequence identity with a previously reported plasmid, pNDM-HN380 (GenBank accession JX104760), over the backbone and genetic load regions. A blast search further revealed the occurrence of identical or nearly identical IncX3 plasmids carrying bla NDM in other part of China, Korea, Myanmar, India, Oman, Kuwait, Italy, and Canada. Two IncX3 carrying bla NDM were investigated further. Conjugation experiments demonstrated that the IncX3 plasmids could be efficiently transferred to multiple enterobacterial species at frequencies that are comparable or higher than the epidemic IncFII plasmid carrying bla CTX-M (pHK01). In addition, efficient transfer of the NDM plasmids occurred over a range of temperatures. In conclusion, this study demonstrated the important role played by IncX3 in the dissemination of NDM and the occurrence of pNDM-HN380-like plasmids in geographically widespread areas. The high mobility of IncX3 plasmid across different enterobacterial species highlights the ability of this plasmid replicon to be an important vehicle in worldwide dissemination of NDM.

12.
Sci Rep ; 8(1): 15248, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-30323356

RESUMO

Antibiotic resistance is an emerging public health issue. Plasmids are one of the popular carriers to disseminate resistance genes among pathogens. However, the response of plasmid-carrying bacteria to antibiotic treatment and how these bacteria evolve to increase their resistance remain elusive. In this study, we conjugated plasmid pNDM-HK to E. coli J53 recipient cells and selected survivors using different concentrations of the broad spectrum antibiotic meropenem. After selection, transconjugants conferred varying minimum inhibitory concentrations with respect to carbapenems. We sequenced and compared the transcriptomes of transconjugants that exhibited distinct carbapenem susceptibilities, and found that the loss of outer membrane proteins led to antibiotic resistance. Moreover, we identified a novel mutation, G63S, in transcription factor OmpR which moderates the expression of outer membrane proteins. The loss of porins was due to incapability of phosphorylation, which is essential for porin transcription and carbapenem resistance. We also characterized other genes that are regulated by ompR in this mutant, which contributed to bacterial antibiotic resistance. Overall, our studies suggest antibiotic pressure after conjugation might be an alternative pathway to promote antimicrobial resistance.

14.
Hum Vaccin Immunother ; : 1-4, 2018 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-30261157

RESUMO

This study used several datasets of reported and serotyped invasive pneumococcal disease (IPD) cases to estimate vaccine and non-vaccine type incidence in Hong Kong children. Incidence was analyzed by four time periods to indicate pre-PCV (period 1, 1995-2004), private market only (period 2, 2006-2009), and following early (period 3, 2010-2014, mixed use of 7-, 10- and 13-valent vaccines) and more than five years (period 4, 2015-2017, 13-valent vaccine only) of routine implementation (since September 2009). IPD incidence decreased by 85% and 35% in aged < 2 years and aged 2 to < 5 years, respectively, from period 1 to period 4. This was due to a 97% reduction in the serotypes covered by 7-valent vaccine. In period 4, 59% of the disease was caused by serotype 3 and was largely attributed to an ermB positive, novel ST6011 clone. The finding corroborates an increasing body of evidence that the efficacy of the 13-valent vaccine against infection by this serotype is low.

15.
Tuberculosis (Edinb) ; 112: 120-125, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30205964

RESUMO

OBJECTIVE: To perform a prospective evaluation on the diagnostic performance of an in-house developed, duplex nested IS6110 real-time Polymerase-Chain-Reaction (PCR) assay (IS6110-qPCR assay) for rapid pulmonary TB diagnosis. METHODS: A total of 503 sputum specimens were prospectively collected from July 2016 to November 2016. Diagnostic accuracy and optimal cut-off Cycle-threshold (Ct) value for IS6110-qPCR assay was determined by Receiver Operating Characteristic (ROC) curve. Using the optimal cut-off Ct, diagnostic performance of IS6110-qPCR assay was assessed with reference to both bacteriological and clinical information. Meanwhile, limit of detection (LOD) was calculated using Mycobacterium tuberculosis H37Rv as reference strain. RESULT: ROC curve analysis of IS6110-qPCR assay showed a high Area Under the Curve (AUC) value (0.948) with optimal Ct value at 24.140. Prospective analysis of IS6110-qPCR assay with cut-off Ct = 24.140 showed a high overall sensitivity and specificity of 97.2% and 99.7%, respectively. No cross reactivity was observed among all non-tuberculous mycobacteria specimens in this study. LOD analysis on MTB-spiked sputum showed an average detection limit of 5.0 CFU/mL at Ct = 23.18 (±SD, 0.57). CONCLUSION: IS6110-qPCR assay is a highly accurate and cost-effective assay developed for primary screening of suspected TB cases, which is particularly suitable for regions with limited resources but high TB burden.

16.
Infect Control Hosp Epidemiol ; 39(10): 1170-1177, 2018 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-30156177

RESUMO

BACKGROUND: A liver transplant recipient developed hospital-acquired symptomatic hepatitis C virus (HCV) genotype 6a infection 14 months post transplant. OBJECTIVE: Standard outbreak investigation. METHODS: Patient chart review, interviews of patients and staff, observational study of patient care practices, environmental surveillance, blood collection simulation experiments, and phylogenetic study of HCV strains using partial envelope gene sequences (E1-E2) of HCV genotype 6a strains from the suspected source patient, the environment, and the index patient were performed. RESULTS: Investigations and data review revealed no further cases of HCV genotype 6a infection in the transplant unit. However, a suspected source with a high HCV load was identified. HCV genotype 6a was found in a contaminated reusable blood-collection tube holder with barely visible blood and was identified as the only shared item posing risk of transmission to the index case patient. Also, 14 episodes of sequential blood collection from the source patient and the index case patient were noted on the computerized time log of the laboratory barcoding system during their 13 days of cohospitalization in the liver transplant ward. Disinfection of the tube holders was not performed after use between patients. Blood collection simulation experiments showed that HCV and technetium isotope contaminating the tip of the sleeve capping the sleeved-needle can reflux back from the vacuum-specimen tube side to the patient side. CONCLUSIONS: A reusable blood-collection tube holder without disinfection between patients can cause a nosocomial HCV infection. Single-use disposable tube holders should be used according to the recommendations by Occupational Safety and Health Administration and World Health Organization.

17.
Proc Natl Acad Sci U S A ; 115(31): 8003-8008, 2018 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-30012613

RESUMO

Emerging antibiotic resistance among bacterial pathogens has necessitated the development of alternative approaches to combat drug-resistance-associated infection. The abolition of Staphylococcus aureus virulence by targeting multiple-virulence gene products represents a promising strategy for exploration. A multiplex promoter reporter platform using gfp-luxABCDE dual-reporter plasmids with selected promoters from S. aureus-virulence-associated genes was used to identify compounds that modulate the expression of virulence factors. One small-molecule compound, M21, was identified from a chemical library to reverse virulent S. aureus into its nonvirulent state. M21 is a noncompetitive inhibitor of ClpP and alters α-toxin expression in a ClpP-dependent manner. A mouse model of infection indicated that M21 could attenuate S. aureus virulence. This nonantibiotic compound has been shown to suppress the expression of multiple unrelated virulence factors in S. aureus, suggesting that targeting a master regulator of virulence is an effective way to control virulence. Our results illustrate the power of chemical genetics in the modulation of virulence gene expression in pathogenic bacteria.


Assuntos
Antibacterianos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Endopeptidase Clp/antagonistas & inibidores , Regiões Promotoras Genéticas , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/metabolismo , Staphylococcus aureus/patogenicidade , Animais , Antibacterianos/química , Proteínas de Bactérias/metabolismo , Modelos Animais de Doenças , Endopeptidase Clp/metabolismo , Camundongos , Infecções Estafilocócicas/genética , Infecções Estafilocócicas/metabolismo , Infecções Estafilocócicas/patologia , Staphylococcus aureus/genética
18.
J Clin Microbiol ; 56(7)2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29720431

RESUMO

A newly recognized pneumococcal serotype, 35D, which differs from the 35B polysaccharide in structure and serology by not binding to factor serum 35a, was recently reported. The genetic basis for this distinctive serology is due to the presence of an inactivating mutation in wciG, which encodes an O-acetyltransferase responsible for O-acetylation of a galactofuranose. Here, we assessed the genomic data of a worldwide pneumococcal collection to identify serotype 35D isolates and understand their geographical distribution, genetic background, and invasiveness potential. Of 21,980 pneumococcal isolates, 444 were originally typed as serotype 35B by PneumoCaT. Analysis of the wciG gene revealed 23 isolates from carriage (n = 4) and disease (n = 19) with partial or complete loss-of-function mutations, including mutations resulting in premature stop codons (n = 22) and an in-frame mutation (n = 1). These were selected for further analysis. The putative 35D isolates were geographically widespread, and 65.2% (15/23) of them was recovered after the introduction of pneumococcal conjugate vaccine 13 (PCV13). Compared with serotype 35B isolates, putative serotype 35D isolates have higher invasive disease potentials based on odds ratios (OR) (11.58; 95% confidence interval[CI], 1.42 to 94.19 versus 0.61; 95% CI, 0.40 to 0.92) and a higher prevalence of macrolide resistance mediated by mefA (26.1% versus 7.6%; P = 0.009). Using the Quellung reaction, 50% (10/20) of viable isolates were identified as serotype 35D, 25% (5/20) as serotype 35B, and 25% (5/20) as a mixture of 35B/35D. The discrepancy between phenotype and genotype requires further investigation. These findings illustrated a global distribution of an invasive serotype, 35D, among young children post-PCV13 introduction and underlined the invasive potential conferred by the loss of O-acetylation in the pneumococcal capsule.

19.
Nat Commun ; 9(1): 439, 2018 01 30.
Artigo em Inglês | MEDLINE | ID: mdl-29382822

RESUMO

Drug-resistant superbugs pose a huge threat to human health. Infections by Enterobacteriaceae producing metallo-ß-lactamases (MBLs), e.g., New Delhi metallo-ß-lactamase 1 (NDM-1) are very difficult to treat. Development of effective MBL inhibitors to revive the efficacy of existing antibiotics is highly desirable. However, such inhibitors are not clinically available till now. Here we show that an anti-Helicobacter pylori drug, colloidal bismuth subcitrate (CBS), and related Bi(III) compounds irreversibly inhibit different types of MBLs via the mechanism, with one Bi(III) displacing two Zn(II) ions as revealed by X-ray crystallography, leading to the release of Zn(II) cofactors. CBS restores meropenem (MER) efficacy against MBL-positive bacteria in vitro, and in mice infection model, importantly, also slows down the development of higher-level resistance in NDM-1-positive bacteria. This study demonstrates a high potential of Bi(III) compounds as the first broad-spectrum B1 MBL inhibitors to treat MBL-positive bacterial infection in conjunction with existing carbapenems.


Assuntos
Anti-Infecciosos/farmacologia , Compostos Organometálicos/farmacologia , Inibidores de beta-Lactamases/farmacologia , beta-Lactamases/metabolismo , Animais , Anti-Infecciosos/química , Bismuto/química , Bismuto/metabolismo , Bismuto/farmacologia , Carbapenêmicos/farmacologia , Domínio Catalítico , Cristalografia por Raios X , Cães , Avaliação Pré-Clínica de Medicamentos/métodos , Evolução Molecular , Feminino , Células Madin Darby de Rim Canino/efeitos dos fármacos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana , Compostos Organometálicos/química , Peritonite/tratamento farmacológico , Peritonite/microbiologia , Zinco/metabolismo , Resistência beta-Lactâmica/efeitos dos fármacos , beta-Lactamases/química
20.
Infect Control Hosp Epidemiol ; 39(5): 571-577, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29485019

RESUMO

OBJECTIVEMultidrug-resistant organisms (MDROs) are increasingly reported in residential care homes for the elderly (RCHEs). We assessed whether implementation of directly observed hand hygiene (DOHH) by hand hygiene ambassadors can reduce environmental contamination with MDROs.METHODSFrom July to August 2017, a cluster-randomized controlled study was conducted at 10 RCHEs (5 intervention versus 5 nonintervention controls), where DOHH was performed at two-hourly intervals during daytime, before meals and medication rounds by a one trained nurse in each intervention RCHE. Environmental contamination by MRDOs, such as methicillin-resistant Staphylococcus aureus (MRSA), carbapenem-resistant Acinetobacter species (CRA), and extended-spectrum ß-lactamse (ESBL)-producing Enterobacteriaceae, was evaluated using specimens collected from communal areas at baseline, then twice weekly. The volume of alcohol-based hand rub (ABHR) consumed per resident per week was measured.RESULTSThe overall environmental contamination of communal areas was culture-positive for MRSA in 33 of 100 specimens (33%), CRA in 26 of 100 specimens (26%), and ESBL-producing Enterobacteriaceae in 3 of 100 specimens (3%) in intervention and nonintervention RCHEs at baseline. Serial monitoring of environmental specimens revealed a significant reduction in MRSA (79 of 600 [13.2%] vs 197 of 600 [32.8%]; P<.001) and CRA (56 of 600 [9.3%] vs 94 of 600 [15.7%]; P=.001) contamination in the intervention arm compared with the nonintervention arm during the study period. The volume of ABHR consumed per resident per week was 3 times higher in the intervention arm compared with the baseline (59.3±12.9 mL vs 19.7±12.6 mL; P<.001) and was significantly higher than the nonintervention arm (59.3±12.9 mL vs 23.3±17.2 mL; P=.006).CONCLUSIONSThe direct observation of hand hygiene of residents could reduce environmental contamination by MDROs in RCHEs.Infect Control Hosp Epidemiol 2018;39:571-577.

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