scholarly journals 1836. Genomic Epidemiology of Methicillin-Susceptible Staphylococcus aureus Colonization and Infection among US Army Trainees at Fort Benning, Georgia

2019 ◽  
Vol 6 (Supplement_2) ◽  
pp. S45-S45
Author(s):  
Eugene V Millar ◽  
Patrick McGann ◽  
Michael Ellis ◽  
David Tribble ◽  
Anthony Jones ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Disease Transmission ◽  
Clinical Care ◽  
Military Training ◽  
Anatomic Site ◽  
Us Army ◽  
Genomic Epidemiology ◽  
Strain Diversity ◽  
Mssa Strain ◽  
Fort Benning

Abstract Background Methicillin-susceptible Staphylococcus aureus (MSSA) is a common cause of skin and soft-tissue infection (SSTI). MSSA genomic epidemiology data are limited. We used whole-genome sequencing (WGS) to examine MSSA strain diversity among military trainees, a group known to be at high risk for S. aureus infection and carriage. Methods From July 2012 to December 2014, we conducted a prospective SSTI case–control study among US Army trainees at Fort Benning, GA. Thereafter, we identified MSSA SSTI clusters within select military training classes and performed WGS on clinical and colonizing isolates. We analyzed epidemiologic, clinical, genomic, and phylogenetic data in order to evaluate MSSA strain diversity and patterns of disease transmission. Results A total of 67 SSTI cases from 15 training classes were identified. The median (range) number of cases per class was 4 (3–10). Cases presented for care after a median of 39 (6–101) days of training. Of the 67 cases, 42 (63%) were colonized with MSSA at ≥1 anatomic site. A total of 78 MSSA colonizing isolates were identified at the time trainees presented for clinical care; colonizing isolates were found in the nares (37%), throat (31%), inguinal region (21%), and perianal region (12%). Multilocus sequence typing (MLST) assigned 128 (88%) isolates to 20 known types and 17 isolates to novel types. Among clinical isolates, 60 (90%) were assigned to known types. Sequence Type (ST) 8 was the most frequent type, accounting for 45% and 35% of clinical and colonizing isolates, respectively. The phylogenetic tree of isolates revealed seven major clusters, some of which were composed of a diversity of training classes, specimen types, and STs. These major clusters were further segregated into 15 sub-clusters where there was considerable diversity in intrahost variation. Conclusion Genomic characterization of MSSA infection and colonization isolates among congregate military trainees revealed a broad diversity of strains. There was a clear clonal origin and dissemination of MSSA isolates among close contacts within the ST-8 cluster but this transmission pattern was less apparent for MSSAs from other STs. Disclosures All Authors: No reported Disclosures.

Genomic Epidemiology of Invasive Methicillin-Resistant Staphylococcus aureus Infections Among Hospitalized Individuals in Ontario, Canada

2020 ◽  
Vol 222 (12) ◽  
pp. 2071-2081 ◽  
Author(s):  
Jennifer L Guthrie ◽  
Sarah Teatero ◽  
Sotaro Hirai ◽  
Alex Fortuna ◽  
Daniel Rosen ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Demographic Data ◽  
Public Health Practice ◽  
Acid Resistance ◽  
Fold Increase ◽  
High Genetic Diversity ◽  
Methicillin Resistant ◽  
Genomic Epidemiology ◽  
Healthcare Settings

Abstract Background Prevention and control of methicillin-resistant Staphylococcus aureus (MRSA) infections remain challenging. In-depth surveillance integrating patient and isolate data can provide evidence to better inform infection control and public health practice. Methods We analyzed MRSA cases diagnosed in 2010 (n = 212) and 2016 (n = 214) by hospitals in Ontario, Canada. Case-level clinical and demographic data were integrated with isolate characteristics, including antimicrobial resistance (AMR), classic genotyping, and whole-genome sequencing results. Results Community-associated MRSA (epidemiologically defined) increased significantly from 23.6% in 2010 to 43.0% in 2016 (P < .001). The MRSA population structure changed over time, with a 1.5× increase in clonal complex (CC)8 strains and a concomitant decrease in CC5. The clonal shift was reflected in AMR patterns, with a decrease in erythromycin (86.7% to 78.4%, P = .036) and clindamycin resistance (84.3% to 47.9%, P < .001) and a >2-fold increase in fusidic acid resistance (9.0% to 22.5%, P < .001). Isolates within both CC5 and CC8 were relatively genetically diverse. We identified 6 small genomic clusters—3 potentially related to transmission in healthcare settings. Conclusions Community-associated MRSA is increasing among hospitalized individuals in Ontario. Clonal shifting from CC5 to CC8 has impacted AMR. We identified a relatively high genetic diversity and limited genomic clustering within these dominant CCs.

scholarly journals Heterogeneous ceramide distributions alter spatially resolved growth of Staphylococcus aureus on human stratum corneum

2018 ◽  
Vol 15 (141) ◽  
pp. 20170848 ◽  
Author(s):  
Joseph M. Cleary ◽  
Zachary W. Lipsky ◽  
Minyoung Kim ◽  
Cláudia N. H. Marques ◽  
Guy K. German
Keyword(s):  
Staphylococcus Aureus ◽  
Stratum Corneum ◽  
Bacterial Growth ◽  
Disease Transmission ◽  
Bacterial Species ◽  
Causal Link ◽  
Bacterial Populations ◽  
Human Stratum Corneum ◽  
Spatially Resolved ◽  
Skin Cleansing

Contemporary studies have revealed dramatic changes in the diversity of bacterial microbiota between healthy and diseased skin. However, the prevailing use of swabs to extract the microorganisms has meant that only population ‘snapshots’ are obtained, and all spatially resolved information of bacterial growth is lost. Here we report on the temporospatial growth of Staphylococcus aureus on the surface of the human stratum corneum (SC); the outermost layer of skin. This bacterial species dominates bacterial populations on skin with atopic dermatitis (AD). We first establish that the distribution of ceramides naturally present in the SC is heterogeneous, and correlates with the tissue's structural topography. This distribution subsequently impacts the growth of bacterial biofilms. In the SC retaining healthy ceramide concentrations, biofilms exhibit no spatial preference for growth. By contrast, a depletion of ceramides consistent with reductions known to occur with AD enables S. aureus to use the patterned network of topographical canyons as a conduit for growth. The ability of ceramides to govern bacterial growth is confirmed using a topographical skin canyon analogue coated with the ceramide subcomponent d -sphingosine. Our work appears to explain the causal link between ceramide depletion and increased S. aureus populations that is observed in AD. It may also provide insight into disease transmission as well as improving pre-operative skin cleansing techniques.

scholarly journals Complete Genome Sequence of GD1696, a Low-Virulence Strain of Human-Associated ST398 Methicillin-Susceptible Staphylococcus aureus

2019 ◽  
Vol 8 (28) ◽  
Author(s):  
Jo-Ann McClure ◽  
Steven M. Shideler ◽  
Kunyan Zhang
Keyword(s):  
Staphylococcus Aureus ◽  
Genome Sequence ◽  
Complete Genome Sequence ◽  
Complete Genome ◽  
Sequence Type ◽  
Content Type ◽  
Mssa Strain ◽  
Chromosomal Sequence

The emerging livestock-associated Staphylococcus aureus multilocus sequence type 398 (ST398) appears to have augmented virulence in humans. However, it is unclear if all ST398 strains are equally virulent. Here, we present the chromosomal sequence of a low-virulence ST398 methicillin-susceptible S. aureus (MSSA) strain, GD1696, to investigate ST398 sublineage virulence.

scholarly journals 282Epidemiology of Skin and Soft-Tissue Infections in US Army Trainees at Fort Benning

2014 ◽  
Vol 1 (suppl_1) ◽  
pp. S118-S118
Author(s):  
Michael Ellis ◽  
Carey Schlett ◽  
Tianyuan Cui ◽  
Eugene Millar ◽  
Katrina Crawford ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Soft Tissue Infections ◽  
Us Army ◽  
Fort Benning

Transcranial Doppler Peak Systolic Velocities Overestimate The Risk Of Stroke In Sickle Cell Anemia

Blood ◽  
2013 ◽  
Vol 122 (21) ◽  
pp. 2240-2240 ◽  
Author(s):  
Titilope Ishola ◽  
Charles T. Quinn
Keyword(s):  
Clinical Practice ◽  
Sickle Cell ◽  
Sickle Cell Anemia ◽  
Transcranial Doppler ◽  
Clinical Care ◽  
Pearson Correlation ◽  
Systematic Bias ◽  
Anatomic Site ◽  
The Right

Abstract Background Children with sickle cell anemia (SCA) have a high risk of stroke that can be estimated by transcranial Doppler ultrasonography (TCD). The gold standard TCD measurement to determine the risk of primary stroke is the time-averaged mean of the maximum velocity (TAMMV) in specific intracranial arteries. Peak systolic velocity (PSV), a different TCD measurement, has been proposed as an alternative method for risk stratification, especially for imaging TCD (TCDi) techniques (Jones et al. 2005). Although PSV has been little studied for this purpose, some centers use PSV in addition to TAMMV for the classification of risk of stroke by TCD for clinical care. A systematic bias in the classification of risk of stroke by PSV (higher or lower compared to TAMMV) would substantially affect medical resources and patient outcomes. Objective Describe the test performance characteristics of PSV compared to TAMMV for the classification of risk of stroke in children with SCA and determine the suitability of PSV for classification of TCDs in clinical practice. Methods We studied all patients in our center with homozygous HbSS, sickle-β0-thalassemia, or sickle-Hb D disease (all genotypes referred to here as SCA) who were ≥2 years of age and had a clinical TCD (all by TCDi technique) between 1998-2013. For each patient, the single most recent TCD performed >30 days from a transfusion was used, except for patients receiving chronic transfusions for whom the TCD before the initiation of chronic transfusions was used. Patients were included only once in this analysis. The highest TAMMV and PSV were recorded for the distal internal carotid artery (DICA), bifurcation and middle cerebral artery on the right and left sides of the brain. The TAMMV in each vessel was classified using modified STOP velocity criteria for TCDi: <155, normal; 155-184, conditional; ≥185 abnormal. The PSV in each vessel was classified using criteria proposed by Jones et al.: <200, normal; 200-249, conditional; ≥250 abnormal. Two overall TCD classifications, using either TAMMV or PSV, were made according to standard STOP methods by considering the worst (most abnormal) classification of any vessel as the overall classification. The primary outcome was the multi-level agreement between overall TCD classification based on TAMMV and PSV as measured by the kappa statistic. Kappa was also calculated for individual vessels to determine if agreement differed by anatomic site. Coefficients of determination (r2) were calculated using Pearson correlation. Results We studied 120 patients with SCA [mean age 12.0 years ± 6.0 (S.D.); 51.1% male]. Fifty-nine (49%) had at least one prior transfusion that was given a mean of 588 (median 387) days before the TCD (none ≤40 days). The distribution of overall TCD classification by simultaneous TAMMV and PSV is shown in the Figure (Panel A). The distribution of classifications by TAMMV, compared to PSV, better approximates the expected distribution in a screening population. Classifications by PSV were skewed higher, giving more conditional and abnormal results, when compared to classification by TAMMV (P<0.0001). Kappa was 0.488 (P<0.001) for overall TCD classification, indicating only moderate agreement between the TAMMV and PSV methods. Agreement between TAMMV and PSV classification was highest (“substantial”) in the right and left DICA (k: 0.657–0.717, P<0.001). Agreement was only moderate in all other vessels (k: 0.428–0.539, P<0.001). Compared to TAMMV, use of PSV resulted in misclassification of 28% of overall TCD interpretations (Figure, Panel B); 32 studies (27%) were up-coded (27 normal to conditional; 5 conditional to abnormal). Only 1 study was down-coded (abnormal to conditional). Considering TAMMV and PSV as continuous variables, TAMMV accounted for 84.2-90.2% (r2) of the variation in PSV across different vessels; so, approximately 10-15% of the variability in PSV is not explained by TAMMV. Conclusions The use of PSV (rather than TAMMV) to classify TCDs overestimates the risk of stroke for almost one-third of children with SCA. This systematic bias will unnecessarily increase anxiety, the frequency of follow-up testing, and use of chronic transfusions for primary stroke prophylaxis. PSV should not be used for primary classification of TCDs in clinical practice. Jones A et al. Can peak systolic velocities be used for prediction of stroke in sickle cell anemia? Pediatr Radiol. 2005;35:66-72. Disclosures: No relevant conflicts of interest to declare.

An outbreak of a Multiresistant Methicillin-Susceptible Staphylococcus aureus (MR-MSSA) strain in a Burn Centre: The importance of routine molecular typing

Burns ◽  
2011 ◽  
Vol 37 (5) ◽  
pp. 808-813 ◽  
Author(s):  
S.A. Boers ◽  
I. van Ess ◽  
S.M. Euser ◽  
R. Jansen ◽  
F.R.H. Tempelman ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Molecular Typing ◽  
Mssa Strain

scholarly journals Effects of Amoxicillin, Gentamicin, and Moxifloxacin on the Hemolytic Activity of Staphylococcus aureus In Vitro and In Vivo

2001 ◽  
Vol 45 (1) ◽  
pp. 196-202 ◽  
Author(s):  
Dieter Worlitzsch ◽  
Hayal Kaygin ◽  
Andrea Steinhuber ◽  
Axel Dalhoff ◽  
Konrad Botzenhart ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
Neutrophil Elastase ◽  
Human Neutrophil Elastase ◽  
Mssa Strain ◽  
Subinhibitory Concentrations ◽  
High Level ◽  
Strain Dependent ◽  
Negative Mutant

ABSTRACT In Staphylococcus aureus infection hemolysis caused by the extracellular protein α-toxin encoded by hla is thought to contribute significantly to its multifactorial virulence. In vitro, subinhibitory concentrations of β-lactam antibiotics and fluoroquinolones increase the levels of hla and α-toxin expression, whereas aminoglycosides decrease the levels ofhla and α-toxin expression. In the present study we investigated the effects of subinhibitory concentrations of amoxicillin, gentamicin, and moxifloxacin on hla and α-toxin expression and total hemolysis of S. aureusstrain 8325-4, a high-level α-toxin producer, and its α-toxin-negative mutant, DU 1090, in vitro and in a rat model of chronic S. aureus infection. The levels of expression ofhla and α-toxin and total hemolysis did not differ significantly when amoxicillin, gentamicin, or moxifloxacin was added to cultures of S. aureus strain 8325-4. In vivo, strain 8325-4 induced a significantly increased level of hemolysis in infected pouches compared to that in uninfected control pouches, but the hemolysis was reduced to control levels by treatment with doses of amoxicillin, gentamicin, or moxifloxacin that reduced bacterial numbers by 2 orders of magnitude. Additionally, the effects of subinhibitory concentrations of the three antibiotics on total hemolysis of four methicillin-resistant S. aureus and three methicillin-sensitive S. aureus (MSSA) clinical isolates were assessed in vitro. A significant increase in total hemolysis was observed for only one MSSA strain when it was treated with amoxicillin but not when it was treated with moxifloxacin or gentamicin. When purified α-toxin was incubated with purified human neutrophil elastase, α-toxin was cleaved nearly completely. The results suggest that the penicillin-induced increases in S. aureusα-toxin expression are strain dependent, that reduction of bacterial numbers in vivo counteracts this phenomenon effectively, and finally, that in localized S. aureus infections α-toxin activity is controlled by neutrophil elastase.

scholarly journals Evaluation of Methicillin-Resistant Staphylococcus aureus Skin and Soft-Tissue Infection Prevention Strategies at a Military Training Center

2013 ◽  
Vol 34 (8) ◽  
pp. 841-843 ◽  
Author(s):  
Stephanie M. Morrison ◽  
Carl R. Blaesing ◽  
Eugene V. Millar ◽  
Uzo Chukwuma ◽  
Carey D. Schlett ◽  
...  
Keyword(s):  
Staphylococcus Aureus ◽  
High Risk ◽  
Soft Tissue ◽  
Infection Prevention ◽  
Methicillin Resistant Staphylococcus Aureus ◽  
Military Training ◽  
Soft Tissue Infections ◽  
Training Center ◽  
Prevention Strategies ◽  
Methicillin Resistant

Military trainees are at high risk for skin and soft-tissue infections (SSTIs), especially those caused by methicillin-resistant Staphylococcus aureus (MRSA). A multicomponent hygiene-based SSTI prevention strategy was implemented at a military training center. After implementation, we observed 30% and 64% reductions in overall and MRSA-associated SSTI rates, respectively.

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