Association between susceptibility to photodynamic oxidation and the genetic background of Staphylococcus aureus

Multidrug resistant strains of Staphylococcus aureus are a major cause of skin and soft tissue infections requiring the development of novel and alternative therapeutic options. Photodynamic oxidation is the cornerstone of antimicrobial photodynamic therapy (aPDT) involving the combined use of light and a photosensitizer, which, in the presence of oxygen, originates cytotoxic species capable of oxidizing biological molecules and leads to inactivation of target cells. We have previously shown that susceptibility to aPDT differs significantly across S. aureus isolates and could be associated with several genetic elements. However, the effect of the photodynamic process regarding the S. aureus genetic background has never been reported. We have compared the genetic backgrounds of the strains (SCCmec types, spa types and main clonal complexes) with respect to their susceptibility to protoporphyrin IX-mediated photodynamic inactivation. SCCmec typing revealed no differences in response to photoinactivation. However, detection of spa types and clonal complexes clustered the studied population of MRSA strains according to their response to photodynamic oxidation. Clonal complex 1 (CC1) accounted for elevated resistance and CC30 (ST36) for susceptibility to photoinactivation. Moreover, spa typing identified isolates resistant (t032) and susceptible to photodynamic oxidation (t051, t015). The very tight association between clonal lineages and response to photodynamic inactivation indicates the important role of genetic background for aPDT efficacy. These results make a case for the development of a diagnostic tool with the predictive value of aPDT efficacy according to an identified genetic background of S. aureus isolates. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10096-013-1987-5) contains supplementary material, which is available to authorized user

Transient silencing of antibiotic resistance by mutation represents a significant potential source of unanticipated therapeutic failure

Sporadic literature reports describe isolates of pathogenic bacteria that harbor an antibiotic resistance determinant but remain susceptible to the corresponding antibiotic as a consequence of a genetic defect. Such strains represent a source from which antibiotic resistance may reemerge to cause treatment failure in patients. Here, we report a systematic investigation into the prevalence and nature of this phenomenon, which we term silencing of antibiotic resistance by mutation (SARM). Instances of SARM were detected among 1,470 Staphylococcus aureus isolates through side-by-side comparison of antibiotic resistance genotype (as determined by whole-genome sequencing) versus phenotype (as assessed through susceptibility testing). Of the isolates analyzed, 152 (10.3%) harbored a silenced resistance gene, including 46 (3.1%) that exhibited SARM to currently deployed antistaphylococcal drugs. SARM resulted from diverse mutational events but most commonly through frameshift mutation of resistance determinants as a result of point deletion in poly(A) tracts. The majority (∼90%) of SARM strains reverted to antibiotic resistance at frequencies of ≥10−9; thus, while appearing antibiotic sensitive in the clinical microbiology laboratory, most S. aureus isolates exhibiting SARM will revert to antibiotic resistance at frequencies achievable in patients. In view of its prevalence in a major pathogen, SARM represents a significant potential threat to the therapeutic efficacy of antibiotics

Reaching for the 'first 95': a cross-country analysis of HIV self-testing in nine countries in sub-Saharan Africa

OBJECTIVES: HIV self-testing (HIVST) offers a promising approach to increase HIV diagnosis and advance progress towards the UNAIDS 95-95-95 targets. We aimed to understand patterns of HIVST awareness and utilization in nine sub-Saharan African (SSA) countries, with the goal of identifying populations to target in disseminating this technology. DESIGN: A cross-sectional study. METHODS: We pooled individual-level population-based data from nine Demographic and Health Surveys (DHS) in SSA conducted 2015-2019 (Burundi, Cameroon, Guinea, Malawi, Senegal, Sierra Leone, South Africa, Zambia, Zimbabwe). Primary outcomes were HIVST awareness and utilization. We used logistic regression with survey fixed effects to explore the relationship between sociodemographic characteristics and these outcomes. Models were adjusted for sex, age, rural/urban residence, education, wealth, and marital status. We accounted for complex survey design. RESULTS: The study sample included 177 572 people (66.0% women, mean age 29 ± 10 years), of whom 86.6% [95% confidence interval (95% CI) 86.4-86.7] were unaware of HIVST, 11.7% (95% CI 11.6-11.9) were aware of but never used HIVST, and 1.7% (95% CI 1.6-1.8) had used HIVST. In adjusted models, women were less likely to be aware of HIVST [odds ratio (OR) 0.75, 95% CI 0.71-0.79], but more likely to have used HIVST (OR 1.17, 95% CI 1.03-1.32) compared with men. Rural residents, those who were least educated, and poorest were less likely to have heard of or used HIVST. CONCLUSION: HIVST awareness and uptake were low. Rural, less educated, and lower income populations were least likely to have heard of or used HIVST. Efforts to scale-up HIVST in these settings should aim to reach these less advantaged groups

Ventricular Tachyarrhythmia Detection by Implantable Loop Recording in Patients with Heart Failure and Preserved Ejection Fraction:The VIP-HF study

Aims: The primary aim of the VIP-HF study was to examine the incidence of sustained ventricular tachyarrhythmias (VTs) in heart failure (HF) with mid-range (HFmrEF) or preserved ejection fraction (HFpEF). Secondary aims were to examine the incidence of non-sustained VTs, bradyarrhythmias, HF hospitalizations and mortality. Methods and results: This was an investigator-initiated, prospective, multicentre, observational study of patients with HF and left ventricular ejection fraction (LVEF) >40%. Patients underwent extensive phenotyping, after which an implantable loop recorder was implanted. We enrolled 113 of the planned 250 patients [mean age 73 ± 8 years, 51% women, New York Heart Association class II/III 54%/46%, median N-terminal pro B-type natriuretic peptide 1367 (710–2452) pg/mL and mean LVEF 54 ± 6%; 75% had LVEF >50%]. Eighteen percent had non-sustained VTs and 37% had atrial fibrillation on Holter monitoring. During a median follow-up of 657 (219–748) days, the primary endpoint of sustained VT was observed in one patient. The incidence of the primary endpoint was 0.6 (95% confidence interval 0.2–3.5) per 100 person-years. The incidence of the secondary endpoint of non-sustained VT was 11.5 (7.1–18.7) per 100 person-years. Five patients developed bradyarrhythmias [3.2 (1.4–7.5) per 100 person-years], three were implanted with a pacemaker. In total, 23 patients (20%) were hospitalized for HF [16.3 (10.9–24.4) per 100 person-years]. Fourteen patients (12%) died [8.7 (5.2–14.7) per 100 person-years]; 10 due to cardiovascular causes, and four sudden deaths, one with implantable loop recorder-confirmed bradyarrhythmias as terminal event, three others undetermined. Conclusion: Despite the lower than expected number of included patients, the incidence of sustained VTs in HFmrEF/HFpEF was low. Clinically relevant bradyarrhythmias were more often observed than expected

The value of echocardiographic measurement of epicardial adipose tissue in heart failure patients

AIMS: Epicardial adipose tissue (EAT) is increasingly recognized as an important factor in the pathophysiology of heart failure (HF). Cardiac magnetic resonance (CMR) imaging is the gold‐standard imaging modality to evaluate EAT size, but in contrast to echocardiography, CMR is costly and not widely available. We investigated EAT thickness on echocardiography in relation to EAT volume on CMR, and we assessed the agreement between observers for measuring echocardiographic EAT. METHODS AND RESULTS: Patients with HF and left ventricular ejection fraction >40% were enrolled. All patients underwent CMR imaging and transthoracic‐echocardiography. EAT volume was quantified on CMR short‐axis cine‐stacks. Echocardiographic EAT thickness was measured on parasternal long‐axis and short‐axis views. Linear regression analyses were used to assess the association between EAT volume on CMR and EAT thickness on echocardiography. Intraclass correlation coefficient (ICC) was used to assess the interobserver agreement as well as the intraobserver agreement. EAT on CMR and echocardiography was evaluated in 117 patients (mean age 71 ± 10 years, 49% women and mean left ventricular ejection fraction 54 ± 7%). Mean EAT volume on CMR was 202 ± 64 mL and ranged from 80 to 373 mL. Mean EAT thickness on echocardiography was 3.8 ± 1.5 mm and ranged from 1.7 to 10.2 mm. EAT volume on CMR and EAT thickness on echocardiography were significantly correlated (junior‐observer: r = 0.62, P < 0.001, senior‐observer: r = 0.33, P < 0.001), and up to one‐third of the variance in EAT volume was explained by EAT thickness (R (2) = 0.38, P < 0.001). The interobserver agreement between junior and senior observers for measuring echocardiographic EAT was modest [ICC, 0.65 (95% confidence interval (CI) 0.47–0.77], whereas the intraobserver agreement was good (ICC 0.98, 95% CI 0.84–0.99). CONCLUSIONS: There was a modest correlation between EAT volume on CMR and EAT thickness on echocardiography. Limited agreement between junior and senior observers for measuring echocardiographic EAT was observed. EAT thickness on echocardiography is limited in estimating EAT volume

The clinical and prognostic value of late Gadolinium enhancement imaging in heart failure with mid-range and preserved ejection fraction

Heart failure (HF) with mid-range or preserved ejection fraction (HFmrEF; HFpEF) is a heterogeneous disorder that could benefit from strategies to identify subpopulations at increased risk. We tested the hypothesis that HFmrEF and HFpEF patients with myocardial scars detected with late gadolinium enhancement (LGE) are at increased risk for all-cause mortality. Symptomatic HF patients with left ventricular ejection fraction (LVEF) > 40%, who underwent cardiac magnetic resonance (CMR) imaging were included. The presence of myocardial LGE lesions was visually assessed. T1 mapping was performed to calculate extracellular volume (ECV). Multivariable logistic regression analyses were used to determine associations between clinical characteristics and LGE. Cox regression analyses were used to assess the association between LGE and all-cause mortality. A total of 110 consecutive patients were included (mean age 71 +/- 10 years, 49% women, median N-terminal brain natriuretic peptide (NT-proBNP) 1259 pg/ml). LGE lesions were detected in 37 (34%) patients. Previous myocardial infarction and increased LV mass index were strong and independent predictors for the presence of LGE (odds ratio 6.32, 95% confidence interval (CI) 2.07-19.31, p = 0.001 and 1.68 (1.03-2.73), p = 0.04, respectively). ECV was increased in patients with LGE lesions compared to those without (28.6 vs. 26.6%, p = 0.04). The presence of LGE lesions was associated with a fivefold increase in the incidence of all-cause mortality (hazards ratio 5.3, CI 1.5-18.1, p = 0.009), independent of age, sex, New York Heart Association (NYHA) functional class, NT-proBNP, LGE mass and LVEF. Myocardial scarring on CMR is associated with increased mortality in HF patients with LVEF > 40% and may aid in selecting a subpopulation at increased risk

Prevalence and Incidence of Atrial Fibrillation in Heart Failure with Mildly Reduced or Preserved Ejection Fraction:(Additive) Value of Implantable Loop Recorders

BACKGROUND: Atrial fibrillation (AF) is common in heart failure with mildly reduced or preserved ejection fraction (HFmrEF/HFpEF) and has a negative impact on outcome. Reliable data on prevalence, incidence, and detection of AF from contemporary, prospective HFmrEF/HFpEF studies are scarce.METHODS: This was a prespecified sub-analysis from a prospective, multicenter study. Patients with HFmrEF/HFpEF underwent 12-lead electrocardiography (ECG), 24 h Holter monitoring, and received an implantable loop recorder (ILR) at the study start. During the 2 year follow-up, rhythm monitoring was performed via ILR, yearly ECG, and two yearly 24 h Holter monitors.RESULTS: A total of 113 patients were included (mean age 73 ± 8 years, 75% HFpEF). At baseline, 70 patients (62%) had a diagnosis of AF: 21 paroxysmal, 18 persistent, and 31 permanent AF. At study start, 45 patients were in AF. Of the 43 patients without a history of AF, 19 developed incident AF during a median follow-up of 23 [15-25] months (44%; incidence rate 27.1 (95% confidence interval 16.3-42.4) per 100 person-years). Thus, after the 2-year follow-up, 89 patients (79%) had a diagnosis of AF. In 11/19 incident AF cases (i.e., 58%), AF was solely detected on the ILR. Yearly 12-lead ECG detected six incident AF cases and four of these cases were also detected on two yearly 24 h Holter monitors. Two incident AF cases were detected on an unplanned ECG/Holter.CONCLUSIONS: Atrial fibrillation is extremely common in heart failure with HFmrEF/HFpEF and may inform on symptom evaluation and treatment options. AF screening with an ILR had a much higher diagnostic yield than conventional modalities.</p

Staphylococcus saprophyticus from clinical and environmental origins have distinct biofilm composition

Biofilm formation has been shown to be critical to the success of uropathogens. Although Staphylococcus saprophyticus is a common cause of urinary tract infections, its biofilm production capacity, composition, genetic basis, and origin are poorly understood. We investigated biofilm formation in a large and diverse collection of S. saprophyticus (n = 422). Biofilm matrix composition was assessed in representative strains (n = 63) belonging to two main S. saprophyticus lineages (G and S) recovered from human infection, colonization, and food-related environment using biofilm detachment approach. To identify factors that could be associated with biofilm formation and structure variation, we used a pangenome-wide association study approach. Almost all the isolates (91%; n = 384/422) produced biofilm. Among the 63 representative strains, we identified eight biofilm matrix phenotypes, but the most common were composed of protein or protein-extracellular DNA (eDNA)-polysaccharides (38%, 24/63 each). Biofilms containing protein-eDNA-polysaccharides were linked to lineage G and environmental isolates, whereas protein-based biofilms were produced by lineage S and infection isolates (p < 0.05). Putative biofilm-associated genes, namely, aas, atl, ebpS, uafA, sasF, sasD, sdrH, splE, sdrE, sdrC, sraP, and ica genes, were found with different frequencies (3-100%), but there was no correlation between their presence and biofilm production or matrix types. Notably, icaC_1 was ubiquitous in the collection, while icaR was lineage G-associated, and only four strains carried a complete ica gene cluster (icaADBCR) except one that was without icaR. We provided evidence, using a comparative genomic approach, that the complete icaADBCR cluster was acquired multiple times by S. saprophyticus and originated from other coagulase-negative staphylococci. Overall, the composition of S. saprophyticus biofilms was distinct in environmental and clinical isolates, suggesting that modulation of biofilm structure could be a key step in the pathogenicity of these bacteria. Moreover, biofilm production in S. saprophyticus is ica-independent, and the complete icaADBCR was acquired from other staphylococci