The proportion of Staphylococcus aureus isolates that were methicillin resistant (MRSA) increased from 35.9% in 1992 to 64.4% in 2003 for hospitals in the National Nosocomial Infections Surveillance ...system. During the same period, there was a decrease in resistance rates for several non-β-lactam drugs among the MRSA isolates.
There have been increases in both the rate and the severity of
C. difficile
–associated disease. This report details the emergence of an epidemic strain, BI/NAP1, in eight health care facilities over ...the past five years. This strain is associated with increased resistance to fluoroquinolone as well as the presence of a novel toxin known as binary toxin CDT.
This report details the emergence of an epidemic strain, BI/NAP1, in eight health care facilities over the past five years. This strain is associated with increased resistance to fluoroquinolone as well as the presence of a novel toxin known as binary toxin CDT.
Clostridium difficile
is a gram-positive, anaerobic, spore-forming bacillus that can cause pseudomembranous colitis and other
C. difficile
–associated diseases. Studies during the 1970s showed that two toxins, A and B, were involved in the pathogenesis of
C. difficile
–associated disease.
1
–
5
Transmission occurs primarily in health care facilities, where exposure to antimicrobial drugs (the major risk factor for
C. difficile
–associated disease) and environmental contamination by
C. difficile
spores are more common.
6
Certain strains of
C. difficile
have a propensity to cause outbreaks, including multistate outbreaks in health care facilities.
7
Because these outbreak-associated strains are resistant to certain antimicrobial agents, . . .
Bacterial microcompartments (BMCs) are organelles that encapsulate functionally linked enzymes within a proteinaceous shell. The prototypical example is the carboxysome, which functions in carbon ...fixation in cyanobacteria and some chemoautotrophs. It is increasingly apparent that diverse heterotrophic bacteria contain BMCs that are involved in catabolic reactions, and many of the BMCs are predicted to have novel functions. However, most of these putative organelles have not been experimentally characterized. In this study, we sought to discover the function of a conserved BMC gene cluster encoded in the majority of the sequenced planctomycete genomes. This BMC is especially notable for its relatively simple genetic composition, its remote phylogenetic position relative to characterized BMCs, and its apparent exclusivity to the enigmatic Verrucomicrobia and Planctomycetes. Members of the phylum Planctomycetes are known for their morphological dissimilarity to the rest of the bacterial domain: internal membranes, reproduction by budding, and lack of peptidoglycan. As a result, they are ripe for many discoveries, but currently the tools for genetic studies are very limited. We expanded the genetic toolbox for the planctomycetes and generated directed gene knockouts of BMC-related genes in Planctomyces limnophilus. A metabolic activity screen revealed that BMC gene products are involved in the degradation of a number of plant and algal cell wall sugars. Among these sugars, we confirmed that BMCs are formed and required for growth on l-fucose and l-rhamnose. Our results shed light on the functional diversity of BMCs as well as their ecological role in the planctomycetes, which are commonly associated with algae.
In proximity to seismic operations, bowhead whales (Balaena mysticetus) decrease their calling rates. Here, we investigate the transition from normal calling behavior to decreased calling and ...identify two threshold levels of received sound from airgun pulses at which calling behavior changes. Data were collected in August-October 2007-2010, during the westward autumn migration in the Alaskan Beaufort Sea. Up to 40 directional acoustic recorders (DASARs) were deployed at five sites offshore of the Alaskan North Slope. Using triangulation, whale calls localized within 2 km of each DASAR were identified and tallied every 10 minutes each season, so that the detected call rate could be interpreted as the actual call production rate. Moreover, airgun pulses were identified on each DASAR, analyzed, and a cumulative sound exposure level was computed for each 10-min period each season (CSEL10-min). A Poisson regression model was used to examine the relationship between the received CSEL10-min from airguns and the number of detected bowhead calls. Calling rates increased as soon as airgun pulses were detectable, compared to calling rates in the absence of airgun pulses. After the initial increase, calling rates leveled off at a received CSEL10-min of ~94 dB re 1 μPa2-s (the lower threshold). In contrast, once CSEL10-min exceeded ~127 dB re 1 μPa2-s (the upper threshold), whale calling rates began decreasing, and when CSEL10-min values were above ~160 dB re 1 μPa2-s, the whales were virtually silent.
Nucleic acid amplification testing (NAAT) is increasingly being adopted for diagnosis of Clostridium difficile infection (CDI). Data from 3 states conducting population-based CDI surveillance showed ...increases ranging from 43% to 67% in CDI incidence attributable to changing from toxin enzyme immunoassays to NAAT. CDI surveillance requires adjustment for testing methods.
Advancements in comparative genomics have generated significant interest in defining applications for health care-associated pathogens. Clinical microbiology, however, relies on increasingly ...automated platforms to quickly identify pathogens, resistance mechanisms, and therapy options within Clinical Laboratory Improvement Amendments (CLIA)- and FDA-approved frameworks. Additionally, and most notably, health care-associated pathogens, especially those that are resistant to antibiotics, represent a diverse spectrum of genera harboring complex genetic targets, including antibiotic, biocide, and virulence determinants that can be highly transmissible and, at least for antibiotic resistance, serve as potential targets for containment efforts. U.S. public health investments have focused on rapidly detecting outbreaks and emerging resistance in health care-associated pathogens using reference, culture-based, and molecular methods that are distributed, for example, across national laboratory network infrastructures. Herein we describe the public health applications of genomic science that are built from the top-down for broad surveillance, as well as the bottom-up, starting with identification of infections and infectious clusters. For health care-associated, including antimicrobial-resistant, pathogens, we propose a combination of top-down and bottom-up genomic approaches leveraged across the public health spectrum, from local infection control, to regional and national containment efforts, to national surveillance for understanding emerging strain ecology and fitness of health care pathogens.
Direct amination of heteroarenes and arenes has been achieved in a one‐pot CH zincation/copper‐catalyzed electrophilic amination procedure. This amination method provides an efficient and rapid ...approach to access a diverse range of heteroaromatic and aromatic amines including those previously inaccessible using CH amination methods. The mild reaction conditions and good functional‐group compatibility demonstrate its great potential for the synthesis of important and complex amines.
Direct amination of heteroarenes and arenes has been achieved in a one‐pot zincation/Cu(OAc)2‐catalyzed amination sequence using O‐acylhydroxylamines. The method provides a rapid and efficient approach to a range of aromatic and heteroaromatic amines, including those which were previously inaccessible by using CH amination methods. tmp=2,2,6,6‐tetramethylpiperidide.
Toxins A and B are the primary virulence factors of
Clostridium difficile. Since 2002, an epidemic of
C difficile-associated disease with increased morbidity and mortality has been present in Quebec ...province, Canada. We characterised the dominant strain of this epidemic to determine whether it produces higher amounts of toxins A and B than those produced by non-epidemic strains.
We obtained isolates from 124 patients from Centre Hospitalier Universitaire de Sherbrooke in Quebec. Additional isolates from the USA, Canada, and the UK were included to increase the genetic diversity of the toxinotypes tested. Isolate characterisation included toxinotyping, pulsed-field gel electrophoresis (PFGE), PCR ribotyping, detection of a binary toxin gene, and detection of deletions in a putative negative regulator for toxins A and B (
tcdC). By use of an enzyme-linked immunoassay, we measured the in-vitro production of toxins A and B by epidemic strain and non-dominant strain isolates.
The epidemic strain was characterised as toxinotype III, North American PFGE type 1, and PCR-ribotype 027 (NAP1/027). This strain carried the binary toxin gene
cdtB and an 18-bp deletion in
tcdC. We isolated this strain from 72 patients with
C difficile-associated disease (58 67% of 86 with health-care-associated disease; 14 37% of 38 with community-acquired disease). Peak median (IQR) toxin A and toxin B concentrations produced in vitro by NAP1/027 were 16 and 23 times higher, respectively, than those measured in isolates representing 12 different PFGE types, known as toxinotype 0 (toxin A, median 848 μg/L IQR 504–1022
vs 54 μg/L 23–203; toxin B, 180 μg/L 137–210
vs 8 μg/L 5–25; p<0·0001 for both toxins).
The severity of
C difficile-associated disease caused by NAP1/027 could result from hyperproduction of toxins A and B. Dissemination of this strain in North America and Europe could lead to important changes in the epidemiology of
C difficile-associated disease.
Background. The incidence of Clostridium difficile– associated disease (CDAD) is increasing. There are few data on the short-term and long-term attributable costs of CDAD. The objective of this study ...was to determine the acute and 180-day attributable inpatient costs of CDAD. Methods. We performed a retrospective cohort study of all patients without operating room costs who were admitted for ⩾ 48 h to Barnes-Jewish Hospital, a tertiary care hospital in St. Louis, Missouri, 1 January 2003– 31 December 2003 (n=24,691). Attributable costs of CDAD were determined by multivariable linear regression and propensity-score matched-pairs analyses (n=684) for the hospitalization in which CDAD occurred and per patient over a 180-day period, including the initial hospitalization. Results. CDAD was associated with $2454 (95% confidence interval, $2380– $2950; increase in cost, 41%) attributable costs per CDAD episode by linear regression and with $3240 attributable costs (P< .001; increase in cost, 33%) by propensity-score matched-pairs analysis. CDAD was associated with $5042 (95% confidence interval, $3797– $6481; increase in cost, 53%) attributable inpatient costs over 180 days by linear regression and with $7179 attributable costs for inpatient care (P< .001; 48% increase in costs) by propensity-score matched-pairs analysis. Conclusions. CDAD was associated with a significant increase in costs for inpatient care and increased costs at 180 days after the initial hospitalization when the CDAD episode occurred.
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