How the novel influenza H7N9 virus crossed species barrier from avian to human is intriguing. Extrapolation from previous studies on H5N1 can be misleading as illustrated by crystallographic studies on the H7 hemagglutinin with G226L substitution; crystal structure of the neuraminidase N9 showed that R294K substitution interferes with binding to sialic acid or antiviral drugs and reduces viral fitness.
The majority of emerging infectious disease agents affecting human are RNA viruses that originate from animals. Globalization and climate changes continue to reshape the geographical distribution of humans, animals, vectors, and microbes, and allow their mixing to occur at an unprecedentedly high frequency. These have led to interspecies transmission of numerous emerging pathogens in the past decades, such as avian (H5N1 and H7N9) and pandemic (H1N1) influenza viruses, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) coronaviruses. The increasing demand for food, sex, and drugs associated with the rising, mobile and ageing populations and the economic growth in the rapidly developing geographical regions involved in the Belt and Road Initiative may lead to outbreaks of zoonoses, sexually transmitted diseases, antimicrobial resistance, and infections associated with contaminated pharmaceutical products. These outbreaks often occur in the setting of marked lagging in hygiene, public health and regulatory measures and are accompanied by microbial genome adaptation to the changing microbiomes in human, animal and the ecosystem. The outbreak of SARS in 2003 has sparked an explosion of novel coronavirus discovery by virological surveillance in animals and human. The number of coronaviruses has increased from 10 before 2003 to over 40 with complete genomes within the past 14 years. Except for HCoV-HKU1 and HCoV-NL63 which are found in human, the majority of these newly discovered coronaviruses are found in bats and birds. In addition to enhancing our understanding in the phylogeny and evolution of coronaviruses, animal surveillance for novel viruses has strategic importance in the control of emerging infectious diseases through genomic analysis, study of pathogenesis, and development of rapid diagnostic tests, antimicrobials, vaccines and infection control strategies.
DOI : 10.4103/1995-7645.243069 Anahtar Kelimeler :
Belt and Road Initiative, Emerging infectious diseases, Zoonoses, Interspecies transmission
ISSN: 2352-4146 Cilt: 11 Sayı: 13 Sayfa: 13 - 13
Viruses are important pathogens causing respiratory tract infections both in the community and health‐care facility settings. They are extremely common causes of morbidity in the competent hosts and some are associated with significant mortality in the compromised individuals. With wider application of molecular techniques, novel viruses are being described and old viruses are found to have new significance in different epidemiological and clinical settings. Some of these emerging pathogens may have the potential to cause pandemics or global spread of a severe disease, as exemplified by severe acute respiratory syndrome and avian influenza. Antiviral therapy of viral respiratory infections is often unnecessary in the competent hosts because most of them are self‐limiting and effective agents are not always available. In the immunocompromised individuals or for infections caused by highly pathogenic viruses, such as avian influenza viruses (AIV), antiviral treatment is highly desirable, despite the fact that many of the agents may not have undergone stringent clinical trials. In immunocompetent hosts, antiviral therapy can be stopped early because adaptive immune response can usually be mounted within 5–14 days. However, the duration of antiviral therapy in immunosuppressed hosts depends on clinical and radiological resolution, the degree and duration of immunosuppression, and therefore maintenance therapy is sometimes needed after the initial response. Immunotherapy and immunoprophylaxis appear to be promising directions for future research. Appropriate and targeted immunomodulation may play an important adjunctive role in some of these infections by limiting the extent of end‐organ damage and multi‐organ failure in some fulminant infections.
DOI : 10.1111/j.1440-1843.2008.01404.x
Summary A 59-yr-old male alcoholic with bilateral nephrocalcinosis and upper urinary tract stones presented with fever, acute abdominal signs and ascites. Laparotomy revealed the presence of 1.5 litres of ascitic fluid and confirmed right-sided acute pyelonephritis. Culture of urine from the renal pelvis obtained during surgery was positive for Mycoplasma hominis. Initial therapy with cefuroxime failed and doxycycline was later initiated when culture was positive for Mycoplasma hominis, with definite clinical improvement. This is an unusual case of acute pyelonephritis with peritoneal signs and ascites due to Mycoplasma hominis in an elderly male who had no recent history of urinary tract instrumentation.
Rhinovirus has been neglected in the past because it was generally perceived as a respiratory virus only capable of causing mild common cold. Contemporary epidemiological studies using molecular assays have shown that rhinovirus is frequently detected in adult and pediatric patients with upper or lower respiratory tract infections. Severe pulmonary and extrapulmonary complications are increasingly recognized. Contrary to popular belief, some rhinoviruses can actually replicate well at 37 °C and infect the lower airway in humans. The increasing availability of multiplex PCR panels allows rapid detection of rhinovirus and provides the opportunity for timely treatment and early recognition of outbreaks. Recent advances in the understanding of host factors for viral attachment and replication, and the host immunological response in both asthmatic and non-asthmatic individuals, have provided important insights into rhinovirus infection which are crucial in the development of antiviral treatment. The identification of novel drugs has been accelerated by repurposing clinically-approved drugs. As humoral antibodies induced by past exposure and vaccine antigen of a particular serotype cannot provide full coverage for all rhinovirus serotypes, novel vaccination strategies are required for inducing protective response against all rhinoviruses.
MBEToolbox is an extensible MATLAB-based software package for analysis of DNA and protein sequences. MBEToolbox version 2.0 includes enhanced functions for phylogenetic analyses by the maximum likelihood method. For example, it is capable of estimating the synonymous and nonsynonymous substitution rates using a novel or several known codon substitution models. MBEToolbox 2.0 introduces new functions for estimating site-specific evolutionary rates by using a maximum likelihood method or an empirical Bayesian method. It also incorporates several different methods for recombination detection. Multi-platform versions of the software are freely available at http://www.bioinformatics.org/mbetoolbox/.
We report the 1st case of methicillin-resistant Staphylococcus aureus (MRSA) septic arthritis after acupuncture, with articular cartilage destruction and chronic osteomyelitis. The patient responded to arthrotomy, synovectomy, and 6 months of antibiotics. The emergence of community-associated MRSA infections would further aggravate the problem. Strict adherence to proper infection control guidelines is mandatory.
DOI : 10.1016/j.diagmicrobio.2008.08.023 Anahtar Kelimeler :
MRSA, Septic arthritis, Acupuncture, Infection control
ISSN: 0732-8893 Sayı: 1 Cilt: 63 Sayfa: 92-95
: This study was performed to study the clinical presentations,treatment, and outcome of six cases of nocardial infection in the systemic lupus erythematosus (SLE) population living in Hong Kong and compare these cases with those reported in the English literature. Methods: Records of 215 SLEpatients who attended our lupus and rheumatology clinics were reviewed, and cases of nocardial infection were retrieved and studied in detail. A Medline search from 1966 to 1995 was performed to identify other reported cases. The microbiology, diagnosis, and treatment strategies of nocardiosis were assessed. Results: Six cases of nocardiosis were found in our lupus series, giving a prevalence of 2.8%. Another 26 cases of nocardial infection in SLE were reported in the literature. All except one were caused by Nocardia asteroides. The lung was the commonest site of involvement (81 %), followed by the central nervous system (CNS) (13%). The mortality was high (35%), especially when the CNS was involved (75%). Sulphonamides were the mainstay of treatment, and adjunctive surgical procedures may be needed for suppurative complications. Conclusions: Nocardiosis has been increasingly recognized in SLE.Although still uncommon, it is an important opportunistic infection because it is curable and mortality is usually caused by delay in diagnosis and treatment. A high index of suspicion, an aggressive approach to diagnosis, and early empirical therapy are essential principles of management.
Although exact statistics are lacking, body modifications for cosmetic purposes are performed in many countries. The commonest forms include tattooing, body piercing, and breast and facial augmentation using implants or injectable fillers. Liposuction and, to a lesser extent, mesotherapy are also practiced in many countries. Infective complications of these procedures include local infections, transmission of bloodborne pathogens (viral hepatitis and human immunodeficiency virus), and distant infections such as infective endocarditis. Presence of foreign bodies, long healing time of piercing wounds, and poor compliance with infection control practices of some practitioners all predispose the recipients to infections. Apart from the endogenous microbial flora of the skin and mucosae, atypical mycobacteria, especially the rapid growers, have emerged as some of the most important pathogens in such settings. Outbreaks of infection are commonly reported. We hereby review the current knowledge of the topic with specific focus on infections associated with tattooing, body piercing, breast augmentation, mesotherapy, liposuction, and tissue filler injections. Greater awareness among consumers and health-care professionals, as well as more stringent regulations by the health authorities, is essential to minimize the health risks arising from these procedures.
DOI : 10.1016/j.jfma.2012.10.016 Anahtar Kelimeler :
body modification, body piercing, breast implants, mesotherapy, tattooing
ISSN: 0929-6646 Cilt: 111 Sayı: 12 Sayfa: 667 - 681
Summary Background Antivirals (eg, oseltamivir) are important for mitigating influenza epidemics. In 2007, an oseltamivir-resistant influenza seasonal A H1N1 strain emerged and spread to global fixation within 1 year. This event showed that antiviral-resistant (AVR) strains can be intrinsically more transmissible than their contemporaneous antiviral-sensitive (AVS) counterpart. Surveillance of AVR fitness is therefore essential. Our objective was to develop a simple method for estimating AVR fitness from surveillance data. Methods We defined the fitness of AVR strains as their reproductive number relative to their co-circulating AVS counterparts. We developed a simple method for real-time estimation of AVR fitness from surveillance data. This method requires only information on generation time without other specific details regarding transmission dynamics. We first used simulations to validate this method by showing that it yields unbiased and robust fitness estimates in most epidemic scenarios. We then applied this method to two retrospective case studies and one hypothetical case study. Findings We estimated that the oseltamivir-resistant A H1N1 strain that emerged in 2007 was 4% (95% credible interval [CrI] 3–5) more transmissible than its oseltamivir-sensitive predecessor and the oseltamivir-resistant pandemic A H1N1 strain that emerged and circulated in Japan during 2013–14 was 24% (95% CrI 17–30) less transmissible than its oseltamivir-sensitive counterpart. We show that in the event of large-scale antiviral interventions during a pandemic with co-circulation of AVS and AVR strains, our method can be used to inform optimal use of antivirals by monitoring intrinsic AVR fitness and drug pressure on the AVS strain. Interpretation We developed a simple method that can be easily integrated into contemporary influenza surveillance systems to provide reliable estimates of AVR fitness in real time. Funding Research Fund for the Control of Infectious Disease (09080792) and a commissioned grant from the Health and Medical Research Fund from the Government of the Hong Kong Special Administrative Region, Harvard Center for Communicable Disease Dynamics from the National Institute of General Medical Sciences (grant number U54 GM088558), Area of Excellence Scheme of the Hong Kong University Grants Committee (grant number AoE/M-12/06).
The drastic increase in the number of coronaviruses discovered and coronavirus genomes being sequenced have given us an unprecedented opportunity to perform genomics and bioinformatics analysis on this family of viruses. Coronaviruses possess the largest genomes (26.4 to 31.7 kb) among all known RNA viruses, with G + C contents varying from 32% to 43%. Variable numbers of small ORFs are present between the various conserved genes (ORF1ab, spike, envelope, membrane and nucleocapsid) and downstream to nucleocapsid gene in different coronavirus lineages. Phylogenetically, three genera, Alphacoronavirus, Betacoronavirus and Gammacoronavirus, with Betacoronavirus consisting of subgroups A, B, C and D, exist. A fourth genus, Deltacoronavirus, which includes bulbul coronavirus HKU11, thrush coronavirus HKU12 and munia coronavirus HKU13, is emerging. Molecular clock analysis using various gene loci revealed that the time of most recent common ancestor of human/civet SARS related coronavirus to be 1999-2002, with estimated substitution rate of 4´10-4 to 2´10-2 substitutions per site per year. Recombination in coronaviruses was most notable between different strains of murine hepatitis virus (MHV), between different strains of infectious bronchitis virus, between MHV and bovine coronavirus, between feline coronavirus (FCoV) type I and canine coronavirus generating FCoV type II, and between the three genotypes of human coronavirus HKU1 (HCoV-HKU1). Codon usage bias in coronaviruses were observed, with HCoV-HKU1 showing the most extreme bias, and cytosine deamination and selection of CpG suppressed clones are the two major independent biological forces that shape such codon usage bias in coronaviruses.
Summary Although in silico analysis have suggested that the antibiotic resistance genes in actinomycetes appear to be the origins of some antibiotic resistance genes, we have shown that recent horizontal transfer of antibiotic resistance genes from actinomycetes to other medically important bacteria have not taken place. Although it has been speculated in Benveniste and Davies’ attractive hypothesis that antibiotic resistance genes of actinomycetes are origins of antibiotic resistance genes in pathogenic bacteria because the actinomycetes require mechanisms such as metabolic enzymes (encoded by the antibiotic resistance genes) to degrade the antibiotics they produce or to transport the antibiotics outside the bacterial cells, this hypothesis has never been proven. Both the phylogenetic tree constructed using 16S rRNA gene sequences and that constructed using concatenated amino acid sequences of 15 housekeeping genes extracted from 90 bacterial genomes showed that the actinomycetes is more ancestral to most other bacteria, including the pathogenic Gram-negative bacteria, Gram-positive bacteria, and Chlamydia species. Furthermore, the tetracycline resistance gene of Bifidobacterium longum is more ancestral to those of other pathogenic bacteria and the actinomycetes, which is in line with the ancestral position of B. longum. These suggest that the evolution of antibiotic resistance genes of antibiotic-producing bacteria in general parallels the evolution of the corresponding bacteria. The ancestral position of the antibiotic resistance genes in actinomycetes is probably unrelated to the fact that they produce antibiotics, but simply because actinomycetes are more ancestral than pathogenic bacteria.