Transiently silent acquired antimicrobial resistance: an emerging challenge in susceptibility testing.

Acquisition and expression of antimicrobial resistance (AMR) mechanisms in bacteria are often associated with a fitness cost. Thus, evolutionary adaptation and fitness cost compensation may support the advance of subpopulations with a silent resistance phenotype when the antibiotic selection pressure is absent. However, reports are emerging on the transient nature of silent acquired AMR, describing genetic alterations that can change the expression of these determinants to a clinically relevant level of resistance, and the association with breakthrough infections causing treatment failures. This phenomenon of transiently silent acquired AMR (tsaAMR) is likely to increase, considering the overall expansion of acquired AMR in bacterial pathogens. Moreover, the augmented use of genotypic methods in combination with conventional phenotypic antimicrobial susceptibility testing (AST) will increasingly enable the detection of genotype and phenotype discrepancy. This review defines tsaAMR as acquired antimicrobial resistance genes with a corresponding phenotype within the wild-type distribution or below the clinical breakpoint for susceptibility for which genetic alterations can mediate expression to a clinically relevant level of resistance. References to in vivo resistance development and therapeutic failures caused by selected resistant subpopulations of tsaAMR in Gram-positive and Gram-negative pathogens are given. We also describe the underlying molecular mechanisms, including alterations in the expression, reading frame or copy number of AMR determinants, and discuss the clinical relevance concerning challenges for conventional AST.

Enterococcal Membrane Vesicles as Vaccine Candidates.

Enterococcus faecium is a leading cause of nosocomial infections, particularly in immunocompromised patients. The rise of multidrug-resistant E. faecium, including Vancomycin-Resistant Enterococci (VRE), is a major concern. Vaccines are promising alternatives to antibiotics, but there is currently no vaccine available against enterococci. In a previous study, we identified six protein vaccine candidates associated with extracellular membrane vesicles (MVs) produced by nosocomial E. faecium. In this study, we immunized rabbits with two different VRE-derived MV preparations and characterized the resulting immune sera. Both anti-MV sera exhibited high immunoreactivity towards the homologous strain, three additional VRE strains, and eight different unrelated E. faecium strains representing different sequence types (STs). Additionally, we demonstrated that the two anti-MV sera were able to mediate opsonophagocytic killing of not only the homologous strain but also three unrelated heterologous VRE strains. Altogether, our results indicate that E. faecium MVs, regardless of the purification method for obtaining them, are promising vaccine candidates against multidrug-resistant E. faecium and suggest that these naturally occurring MVs can be used as a multi-antigen platform to elicit protective immune responses against enterococcal infections.

Alternative vanHAX promoters and increased vanA-plasmid copy number resurrect silenced glycopeptide resistance in Enterococcus faecium.

BACKGROUND: Vancomycin variable enterococci (VVE) are van-positive isolates with a susceptible phenotype that can convert to a resistant phenotype during vancomycin selection. OBJECTIVES: To describe a vancomycin-susceptible vanA-PCR positive ST203 VVE Enterococcus faecium isolate (VVESwe-S) from a liver transplantation patient in Sweden which reverted to resistant (VVESwe-R) during in vitro vancomycin exposure. METHODS: WGS analysis revealed the genetic differences between the isolates. Expression of the van-operon was investigated by qPCR. Fitness and stability of the revertant were investigated by growth measurements, competition and serial transfer. RESULTS: The VVESwe-R isolate gained high-level vancomycin (MIC >256 mg/L) and teicoplanin resistance (MIC = 8 mg/L). VVESwe-S has a 5'-truncated vanR activator sequence and the VVESwe-R has in addition acquired a 44 bp deletion upstream of vanHAX in a region containing alternative putative constitutive promoters. In VVESwe-R the vanHAX-operon is constitutively expressed at a level comparable to the non-induced prototype E. faecium BM4147 strain. The vanHAX operon of VVESwe is located on an Inc18-like plasmid, which has a 3-4-fold higher copy number in VVESwe-R compared with VVESwe-S. Resistance has a low fitness cost and the vancomycin MIC of VVESwe-R decreased during in vitro serial culture without selection. The reduction in MIC was associated with a decreased vanA-plasmid copy number. CONCLUSIONS: Our data support a mechanism by which vancomycin-susceptible VVE strains may revert to a resistant phenotype through the use of an alternative, constitutive, vanR-activator-independent promoter and a vanA-plasmid copy number increase.

Phase 1 Pharmacokinetic Trial of 2 Intravaginal Rings Containing Different Dose Strengths of Vicriviroc (MK-4176) and MK-2048.

BACKGROUND: Vaginal rings (VRs) are a promising approach for sustained delivery of antiretroviral (ARV) medication to prevent human immunodeficiency virus (HIV) infection in women. Combination ARV VRs could increase efficacy. METHODS: MTN-028, a phase 1 trial in 19 HIV-uninfected women, evaluated 2 VRs containing vicriviroc (VCV) and MK-2048. Participants were randomized 2:1 to a low-dose (VCV, 91 mg; MK-2048, 10 mg) or original-dose (VCV, 182 mg; MK-2048, 30 mg) ring used for 28 days. Safety was assessed by documenting adverse events (AEs). Drug concentrations were evaluated in plasma, cervicovaginal fluid (CVF), and cervical tissue samples. RESULTS: All AEs reported were grade 1 or 2, with no statistically significant differences in related genitourinary AEs or grade ≥2 AEs observed between arms (P = >.99). VCV/MK-2048 concentrations rose rapidly, with higher plasma area under the concentration-time curve (AUC) in the original-dose arm (geometric mean ratio, 3.29 for VCV and 1.49 for MK-2048) and similar AUCs across arms for CVF samples. Cervical tissue concentrations were higher in the original-dose arm (geometric mean ratio, 7.94 for VCV and 6.45 for MK-2048), with greater drug released based on residual drug levels. Plasma and CVF concentrations for both drugs fell rapidly after ring removal. CONCLUSIONS: In this first study evaluating 2 doses of a combination VCV/MK-2048 VR, both rings were found to be safe and well tolerated. VCV and MK-2048 were detectable in plasma, CVF, and cervical tissue samples, and drug release and plasma drug exposure were higher for the original-dose than for the low-dose ring.

Intracellular Tenofovir-Diphosphate and Emtricitabine-Triphosphate in Dried Blood Spots following Directly Observed Therapy.

Studies of daily emtricitabine-tenofovir disoproxil fumarate (FTC-TDF) for HIV preexposure prophylaxis (PrEP) in men who have sex with men (MSM) modeled intracellular tenofovir-diphosphate (TFV-DP) in dried blood spots (DBS) to assess adherence and corresponding PrEP outcomes. We conducted a prospective, randomized, crossover pharmacokinetic study of TFV-DP in DBS during 33%, 67%, or 100% of daily dosing under directly observed therapy (DOT). Participants were assigned to two 12-week dosing regimens, separated by a 12-week washout. Forty-eight adults (25 women) from Denver and San Francisco were included. TFV-DP exhibited a median half-life of 17 days, reaching steady state in 8 weeks. TFV-DP was dose proportional with mean (SD) steady-state concentrations of 530 (159), 997 (267), and 1,605 (405) fmol/punch for the 33%, 67%, and 100% arms, respectively. Prior work in MSM demonstrated clinically meaningful TFV-DP thresholds of 350, 700, and 1,250 fmol/punch, which were estimated 25th percentiles for 2, 4, and 7 doses/week. In the present study, corresponding TFV-DP was within 3% of the prior estimates, and subgroups by site, race, and sex were within 14% of prior estimates, although males had 17.6% (95% confidence intervals [CIs], 6.5, 27.4%) lower TFV-DP than females. The thresholds of 350, 700, and 1,250 fmol/punch were achieved by 75% of men taking ≥1.2, 3.2, and 6 doses/week and 75% of women taking ≥0.6, 2.0, and 5.3 doses/week, indicating that lower dosing reached these thresholds for both sexes. In conclusion, TFV-DP arising from DOT was similar to previous estimates and is useful for interpreting PrEP adherence and study outcomes. (This study has been registered at ClinicalTrials.gov under identifier NCT02022657.).

Population-Level Immune-Mediated Adaptation in HIV-1 Polymerase during the North American Epidemic.

UNLABELLED: Human leukocyte antigen (HLA) class I-associated polymorphisms in HIV-1 that persist upon transmission to HLA-mismatched hosts may spread in the population as the epidemic progresses. Transmission of HIV-1 sequences containing such adaptations may undermine cellular immune responses to the incoming virus in future hosts. Building upon previous work, we investigated the extent of HLA-associated polymorphism accumulation in HIV-1 polymerase (Pol) through comparative analysis of linked HIV-1/HLA class I genotypes sampled during historic (1979 to 1989; n = 338) and modern (2001 to 2011; n = 278) eras from across North America (Vancouver, BC, Canada; Boston, MA; New York, NY; and San Francisco, CA). Phylogenies inferred from historic and modern HIV-1 Pol sequences were star-like in shape, with an inferred most recent common ancestor (epidemic founder virus) sequence nearly identical to the modern North American subtype B consensus sequence. Nevertheless, modern HIV-1 Pol sequences exhibited roughly 2-fold-higher patristic (tip-to-tip) genetic distances than historic sequences, with HLA pressures likely driving ongoing diversification. Moreover, the frequencies of published HLA-associated polymorphisms in individuals lacking the selecting HLA class I allele was on average ∼2.5-fold higher in the modern than in the historic era, supporting their spread in circulation, though some remained stable in frequency during this time. Notably, polymorphisms restricted by protective HLA alleles appear to be spreading to a greater relative extent than others, though these increases are generally of modest absolute magnitude. However, despite evidence of polymorphism spread, North American hosts generally remain at relatively low risk of acquiring an HIV-1 polymerase sequence substantially preadapted to their HLA profiles, even in the present era. IMPORTANCE: HLA class I-restricted cytotoxic T-lymphocyte (CTL) escape mutations in HIV-1 that persist upon transmission may accumulate in circulation over time, potentially undermining host antiviral immunity to the transmitted viral strain. We studied >600 experimentally collected HIV-1 polymerase sequences linked to host HLA information dating back to 1979, along with phylogenetically reconstructed HIV-1 sequences dating back to the virus' introduction into North America. Overall, our results support the gradual spread of many-though not all-HIV-1 polymerase immune escape mutations in circulation over time. This is consistent with recent observations from other global regions, though the extent of polymorphism accumulation in North America appears to be lower than in populations with high seroprevalence, older epidemics, and/or limited HLA diversity. Importantly, the risk of acquiring an HIV-1 polymerase sequence at transmission that is substantially preadapted to one's HLA profile remains relatively low in North America, even in the present era.

Genotypic and functional impact of HIV-1 adaptation to its host population during the North American epidemic.

HLA-restricted immune escape mutations that persist following HIV transmission could gradually spread through the viral population, thereby compromising host antiviral immunity as the epidemic progresses. To assess the extent and phenotypic impact of this phenomenon in an immunogenetically diverse population, we genotypically and functionally compared linked HLA and HIV (Gag/Nef) sequences from 358 historic (1979-1989) and 382 modern (2000-2011) specimens from four key cities in the North American epidemic (New York, Boston, San Francisco, Vancouver). Inferred HIV phylogenies were star-like, with approximately two-fold greater mean pairwise distances in modern versus historic sequences. The reconstructed epidemic ancestral (founder) HIV sequence was essentially identical to the North American subtype B consensus. Consistent with gradual diversification of a "consensus-like" founder virus, the median "background" frequencies of individual HLA-associated polymorphisms in HIV (in individuals lacking the restricting HLA[s]) were ∼ 2-fold higher in modern versus historic HIV sequences, though these remained notably low overall (e.g. in Gag, medians were 3.7% in the 2000s versus 2.0% in the 1980s). HIV polymorphisms exhibiting the greatest relative spread were those restricted by protective HLAs. Despite these increases, when HIV sequences were analyzed as a whole, their total average burden of polymorphisms that were "pre-adapted" to the average host HLA profile was only ∼ 2% greater in modern versus historic eras. Furthermore, HLA-associated polymorphisms identified in historic HIV sequences were consistent with those detectable today, with none identified that could explain the few HIV codons where the inferred epidemic ancestor differed from the modern consensus. Results are therefore consistent with slow HIV adaptation to HLA, but at a rate unlikely to yield imminent negative implications for cellular immunity, at least in North America. Intriguingly, temporal changes in protein activity of patient-derived Nef (though not Gag) sequences were observed, suggesting functional implications of population-level HIV evolution on certain viral proteins.

Emergence of vancomycin-resistant enterococci from vancomycin-susceptible enterococci in hospitalized patients under antimicrobial therapy.

OBJECTIVES: Enterococci are opportunistic pathogens with plastic genomes that evolve, acquire, and transmit antimicrobial-resistant determinants such as vancomycin resistance clusters. While vancomycin-resistant enterococci (VRE) have emerged as successful nosocomial pathogens, the mechanism by which vancomycin-susceptible enterococci (VSE) transform to VRE in hospitalized patients remains understudied. METHODS: Genomes of Enterococcus faecium from two critically ill hospitalized patients subjected to multiple antibiotic therapies, including broad-spectrum antibiotics, were investigated. To identify mechanisms of resistance evolution, genomes of vancomycin-susceptible and -resistant isolates were compared. RESULTS: While VSE isolates were initially identified, VRE strains emerged post-vancomycin therapy. Comparative genomics revealed horizontal transmission of mobile genetic elements containing the Tn1549 transposon, which harbours the vanB-type vancomycin resistance gene cluster. This suggests that broad-spectrum antibiotic stress promoted the transfer of resistance-conferring elements, presumably from another gut inhabitant. CONCLUSION: This is one of the first studies investigating VSE and VRE isolates from the same patient. The mechanism of transmission and the within-patient evolution of vancomycin resistance via mobile genetic elements under antibiotic stress is illustrated. Our findings serve as a foundation for future studies building on this knowledge which can further elucidate the dynamics of antibiotic stress, resistance determinant transmission, and interactions within the gut microbiota.

Adaptive cell wall thickening in Enterococcus faecalis is associated with decreased vancomycin susceptibility.

OBJECTIVES: Enterococcus faecalis can adopt both a commensal and a nosocomial lifestyle, resisting numerous antibiotics. In this study, we aim to investigate the relationship between the cell wall (CW) thickness and decreased susceptibility to vancomycin (VD) in van-gene negative clinical isolates of E. faecalis (nMIC 8 = 2, nMIC 4 = 3, ST30, ST40, and ST59). METHODS: The CW thickness was assessed in VD strains and compared with vancomycin susceptible isolates of the same sequence type (ST) (Vancomycin susceptible [VS]; nMIC 2 = 5). The VD and VS strains were subjected to serial passage (evolved [ev]) with and without vancomycin selection. Subsequent measurements of CW thickness and vancomycin MICs were performed. RESULTS: The VD strains exhibited increased CW thickness when compared with ST-related VS strains (ΔCW thickness VD vs. VS ST30 25 nm, ST59 15 nm, and ST40 1 nm). Serial passages without vancomycin selection led to a decrease in CW thickness and vancomycin MIC in VD strains (ΔCW thickness VD vs. evVD ST30 22 nm, ST59 3 nm, and ST40 2 nm). Serial passages with vancomycin selection caused an increase in CW thickness and vancomycin MIC in ST-related VS strains (ΔCW thickness VS vs. evVS ST30 22 nm, ST59 16 nm, and ST40 1 nm). DISCUSSION: Adaptive changes in CW thickness were observed in response to vancomycin exposure. Increased CW thickness correlated with decreased vancomycin susceptibility, whereas decreased CW thickness correlated with increased vancomycin susceptibility. Core single nucleotide polymorphisms in the evolved mutants were mostly found in genes encoding proteins associated with the cytoplasm or the cytoplasmic membrane. The potential relevance of these adaptive changes is underlined by the observed phenotypes in clinical isolates. Our findings emphasize the importance of monitoring adaptive changes, as vancomycin-resistant enterococci infections are a growing concern.

ZBP1 causes inflammation by inducing RIPK3-mediated necroptosis and RIPK1 kinase activity-independent apoptosis.

Z-DNA binding protein 1 (ZBP1) has important functions in anti-viral immunity and in the regulation of inflammatory responses. ZBP1 induces necroptosis by directly engaging and activating RIPK3, however, the mechanisms by which ZBP1 induces inflammation and in particular the role of RIPK1 and the contribution of cell death-independent signaling remain elusive. Here we show that ZBP1 causes skin inflammation by inducing RIPK3-mediated necroptosis and RIPK1-caspase-8-mediated apoptosis in keratinocytes. ZBP1 induced TNFR1-independent skin inflammation in mice with epidermis-specific ablation of FADD by triggering keratinocyte necroptosis. Moreover, transgenic expression of C-terminally truncated constitutively active ZBP1 (ZBP1ca) in mouse epidermis caused skin inflammation that was only partially inhibited by abrogation of RIPK3-MLKL-dependent necroptosis and fully prevented by combined deficiency in MLKL and caspase-8. Importantly, ZBP1ca induced caspase-8-mediated skin inflammation by RHIM-dependent but kinase activity-independent RIPK1 signaling. Furthermore, ZBP1ca-induced inflammatory cytokine production in the skin was completely prevented by combined inhibition of apoptosis and necroptosis arguing against a cell death-independent pro-inflammatory function of ZBP1. Collectively, these results showed that ZBP1 induces inflammation by activating necroptosis and RIPK1 kinase activity-independent apoptosis.

Interactions between commensal Enterococcus faecium and Enterococcus lactis and clinical isolates of Enterococcus faecium.

Enterococcus faecium (Efm) is a versatile pathogen, responsible for multidrug-resistant infections, especially in hospitalized immunocompromised patients. Its population structure has been characterized by diverse clades (A1, A2, and B (reclassified as E. lactis (Ela)), adapted to different environments, and distinguished by their resistomes and virulomes. These features only partially explain the predominance of clade A1 strains in nosocomial infections. We investigated in vitro interaction of 50 clinical isolates (clade A1 Efm) against 75 commensal faecal isolates from healthy humans (25 clade A2 Efm and 50 Ela). Only 36% of the commensal isolates inhibited clinical isolates, while 76% of the clinical isolates inhibited commensal isolates. The most apparent overall differences in inhibition patterns were presented between clades. The inhibitory activity was mainly mediated by secreted, proteinaceous, heat-stable compounds, likely indicating an involvement of bacteriocins. A custom-made database targeting 76 Bacillota bacteriocins was used to reveal bacteriocins in the genomes. Our systematic screening of the interactions between nosocomial and commensal Efm and Ela on a large scale suggests that, in a clinical setting, nosocomial strains not only have an advantage over commensal strains due to their possession of AMR genes, virulence factors, and resilience but also inhibit the growth of commensal strains.

Prevalence and biopsychosocial indicators of fatigue in cancer patients.

INTRODUCTION: Symptoms of cancer-related fatigue (CRF) can have a significant impact on patients' quality of life and treatment adherence. We aimed to investigate the relationship between CRF and multiple psychosocial and somatic indicators within a large mixed cancer sample. METHODS: In this cross-sectional study, N = 1787 outpatients with cancer were assessed for CRF, pain, anxiety, and depression using validated screening instruments. We further obtained clinical parameters (Hb, CRP, creatinine, leukocytes, ASAT, and ALAT), sociodemographic data (age, gender, income, education level, marital status, parenthood, and living area), and lifestyle factors. Multivariate linear regression models were applied to estimate the impact of each indicator on CRF. RESULTS: Overall, 90.6% of patients experienced some CRF, with 14.8% experiencing severe CRF. No gender difference was found in the prevalence of CRF. Patients with higher levels of pain, depressive symptoms, and lower Hb levels had significantly higher levels of CRF (ps <0.001). Lower levels of CRF were observed in patients who had children (p = 0.03), had less education (p < 0.001), and were physically active for more than 2 h per week before their oncological diagnosis (p = 0.014). The latter was only a significant indicator in the male subsample. CONCLUSION: The present results demonstrate a high prevalence of CRF and highlight that not only somatic and psychosocial factors, but also lifestyle factors prior to diagnosis appear to be associated with the etiology and persistence of CRF. To effectively treat CRF, a biopsychosocial, personalized approach is recommended.

Reversible vancomycin susceptibility within emerging ST1421 Enterococcus faecium strains is associated with rearranged vanA-gene clusters and increased vanA plasmid copy number.

Vancomycin variable enterococci (VVE) are van-positive enterococci with a vancomycin-susceptible phenotype (VVE-S) that can convert to a resistant phenotype (VVE-R) and be selected for during vancomycin exposure. VVE-R outbreaks have been reported in Canada and Scandinavian countries. The aim of this study was to examine the presence of VVE in whole genome sequenced (WGS) Australian bacteremia Enterococcus faecium (Efm) isolates collected through the Australian Group on Antimicrobial resistance (AGAR) network. Eight potential VVEAus isolates, all identified as Efm ST1421, were selected based on the presence of vanA and a vancomycin-susceptible phenotype. During vancomycin selection, two potential VVE-S harboring intact vanHAX genes, but lacking the prototypic vanRS and vanZ genes, reverted to a resistant phenotype (VVEAus-R). Spontaneous VVEAus-R reversion occurred at a frequency of 4-6 × 10-8 resistant colonies per parent cell in vitro after 48 h and led to high-level vancomycin and teicoplanin resistance. The S to R reversion was associated with a 44-bp deletion in the vanHAX promoter region and an increased vanA plasmid copy number. The deletion in the vanHAX promoter region enables an alternative constitutive promoter for the expression of vanHAX. Acquisition of vancomycin resistance was associated with a low fitness cost compared with the corresponding VVEAus-S isolate. The relative proportion of VVEAus-R vs. VVEAus-S decreased over time in serial passages without vancomycin selection. Efm ST1421 is one of the predominant VanA-Efm multilocus sequence types found across most regions of Australia, and has also been associated with a major prolonged VVE outbreak in Danish hospitals.

Acceptability and Preference for 3-Month Versus 1-Month Vaginal Rings for HIV-1 Risk Reduction Among Participants in a Phase 1 Trial.

Background: The monthly dapivirine vaginal ring provides partial protection against HIV, and a longer duration ring may reduce user burden and improve adherence. We examined acceptability and preference for 3-month versus 1-month rings for HIV-1 risk reduction in a phase 1 clinical trial. Materials and Methods: In Microbicide Trials Network-036/International Partnership for Microbicides 047, 49 HIV-negative participants aged 18-45 were randomized to one of two 3-month rings or the 1-month ring. Acceptability ratings were collected at enrollment, week 4, and study exit (week 13). At exit, ring preference was assessed quantitatively among all participants and a randomly selected subset of 24 participants completed in-depth interviews. Quantitative and qualitative findings were integrated to explore factors influencing acceptability and preference. Results: Acceptability of each ring was initially moderate and increased during the trial. Ratings were lower in the 3-month ring arms than the 1-month arm at each time point, including baseline. Most participants (34/47; 72%) preferred a 3-month ring at exit; however, this proportion was significantly lower within some subgroups characterized by site, education, race/ethnicity, and experiences with ring use. Qualitative interviews revealed reservations about hygiene and safety of the 3-month ring, including discomfort with use during menses, but these were usually outweighed by its increased convenience. Conclusions: Both ring durations were highly acceptable at study exit. Although most participants preferred a 3-month ring, preference was more divided in certain subgroups, highlighting the benefit of offering different duration options. Providing additional support to address concerns about hygiene and safety may improve acceptability of a 3-month vaginal ring.

Common breast cancer-predisposition alleles are associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers.

Germline mutations in BRCA1 and BRCA2 confer high risks of breast cancer. However, evidence suggests that these risks are modified by other genetic or environmental factors that cluster in families. A recent genome-wide association study has shown that common alleles at single nucleotide polymorphisms (SNPs) in FGFR2 (rs2981582), TNRC9 (rs3803662), and MAP3K1 (rs889312) are associated with increased breast cancer risks in the general population. To investigate whether these loci are also associated with breast cancer risk in BRCA1 and BRCA2 mutation carriers, we genotyped these SNPs in a sample of 10,358 mutation carriers from 23 studies. The minor alleles of SNP rs2981582 and rs889312 were each associated with increased breast cancer risk in BRCA2 mutation carriers (per-allele hazard ratio [HR] = 1.32, 95% CI: 1.20-1.45, p(trend) = 1.7 x 10(-8) and HR = 1.12, 95% CI: 1.02-1.24, p(trend) = 0.02) but not in BRCA1 carriers. rs3803662 was associated with increased breast cancer risk in both BRCA1 and BRCA2 mutation carriers (per-allele HR = 1.13, 95% CI: 1.06-1.20, p(trend) = 5 x 10(-5) in BRCA1 and BRCA2 combined). These loci appear to interact multiplicatively on breast cancer risk in BRCA2 mutation carriers. The differences in the effects of the FGFR2 and MAP3K1 SNPs between BRCA1 and BRCA2 carriers point to differences in the biology of BRCA1 and BRCA2 breast cancer tumors and confirm the distinct nature of breast cancer in BRCA1 mutation carriers.

RAD51 135G-->C modifies breast cancer risk among BRCA2 mutation carriers: results from a combined analysis of 19 studies.

RAD51 is an important component of double-stranded DNA-repair mechanisms that interacts with both BRCA1 and BRCA2. A single-nucleotide polymorphism (SNP) in the 5' untranslated region (UTR) of RAD51, 135G-->C, has been suggested as a possible modifier of breast cancer risk in BRCA1 and BRCA2 mutation carriers. We pooled genotype data for 8,512 female mutation carriers from 19 studies for the RAD51 135G-->C SNP. We found evidence of an increased breast cancer risk in CC homozygotes (hazard ratio [HR] 1.92 [95% confidence interval {CI} 1.25-2.94) but not in heterozygotes (HR 0.95 [95% CI 0.83-1.07]; P=.002, by heterogeneity test with 2 degrees of freedom [df]). When BRCA1 and BRCA2 mutation carriers were analyzed separately, the increased risk was statistically significant only among BRCA2 mutation carriers, in whom we observed HRs of 1.17 (95% CI 0.91-1.51) among heterozygotes and 3.18 (95% CI 1.39-7.27) among rare homozygotes (P=.0007, by heterogeneity test with 2 df). In addition, we determined that the 135G-->C variant affects RAD51 splicing within the 5' UTR. Thus, 135G-->C may modify the risk of breast cancer in BRCA2 mutation carriers by altering the expression of RAD51. RAD51 is the first gene to be reliably identified as a modifier of risk among BRCA1/2 mutation carriers.

Staphylococcus aureus modulation of innate immune responses through Toll-like (TLR), (NOD)-like (NLR) and C-type lectin (CLR) receptors.

Early recognition of pathogens by the innate immune system is crucial for bacterial clearance. Many pattern recognition receptors (PRRs) such as Toll-like (TLRs) and (NOD)-like (NLRs) receptors have been implicated in initial sensing of bacterial components. The intracellular signaling cascades triggered by these receptors result in transcriptional upregulation of inflammatory pathways. Although this step is crucial for bacterial elimination, it is also associated with the potential for substantial immunopathology, which underscores the need for tight control of inflammatory responses. The leading human bacterial pathogen Staphylococcus aureus expresses over 100 virulence factors that exert numerous effects upon host cells. In this manner, the pathogen seeks to avoid host recognition or perturb PRR-induced innate immune responses to allow optimal survival in the host. These immune system interactions may result in enhanced bacterial proliferation but also provoke systemic cytokine responses associated with sepsis. This review summarizes recent findings on the various mechanisms applied by S. aureus to modulate or interfere with inflammatory responses through PRRs. Detailed understanding of these complex interactions can provide new insights toward future immune-stimulatory therapeutics against infection or immunomodulatory therapeutics to suppress or correct dysregulated inflammation.

Enterococcus faecium TIR-Domain Genes Are Part of a Gene Cluster Which Promotes Bacterial Survival in Blood.

Enterococcus faecium has undergone a transition to a multidrug-resistant nosocomial pathogen. The population structure of E. faecium is characterized by a sharp distinction of clades, where the hospital-adapted lineage is primarily responsible for bacteremia. So far, factors that were identified in hospital-adapted strains and that promoted pathogenesis of nosocomial E. faecium mainly play a role in adherence and biofilm production, while less is known about factors contributing to survival in blood. This study identified a gene cluster, which includes genes encoding bacterial Toll/interleukin-1 receptor- (TIR-) domain-containing proteins (TirEs). The cluster was found to be unique to nosocomial strains and to be located on a putative mobile genetic element of phage origin. The three genes within the cluster appeared to be expressed as an operon. Expression was detected in bacterial culture media and in the presence of human blood. TirEs are released into the bacterial supernatant, and TirE2 is associated with membrane vesicles. Furthermore, the tirE-gene cluster promotes bacterial proliferation in human blood, indicating that TirE may contribute to the pathogenesis of bacteremia.

AURKA F31I polymorphism and breast cancer risk in BRCA1 and BRCA2 mutation carriers: a consortium of investigators of modifiers of BRCA1/2 study.

The AURKA oncogene is associated with abnormal chromosome segregation and aneuploidy and predisposition to cancer. Amplification of AURKA has been detected at higher frequency in tumors from BRCA1 and BRCA2 mutation carriers than in sporadic breast tumors, suggesting that overexpression of AURKA and inactivation of BRCA1 and BRCA2 cooperate during tumor development and progression. The F31I polymorphism in AURKA has been associated with breast cancer risk in the homozygous state in prior studies. We evaluated whether the AURKA F31I polymorphism modifies breast cancer risk in BRCA1 and BRCA2 mutation carriers from the Consortium of Investigators of Modifiers of BRCA1/2. Consortium of Investigators of Modifiers of BRCA1/2 was established to provide sufficient statistical power through increased numbers of mutation carriers to identify polymorphisms that act as modifiers of cancer risk and can refine breast cancer risk estimates in BRCA1 and BRCA2 mutation carriers. A total of 4,935 BRCA1 and 2,241 BRCA2 mutation carriers and 11 individuals carrying both BRCA1 and BRCA2 mutations was genotyped for F31I. Overall, homozygosity for the 31I allele was not significantly associated with breast cancer risk in BRCA1 and BRCA2 carriers combined [hazard ratio (HR), 0.91; 95% confidence interval (95% CI), 0.77-1.06]. Similarly, no significant association was seen in BRCA1 (HR, 0.90; 95% CI, 0.75-1.08) or BRCA2 carriers (HR, 0.93; 95% CI, 0.67-1.29) or when assessing the modifying effects of either bilateral prophylactic oophorectomy or menopausal status of BRCA1 and BRCA2 carriers. In summary, the F31I polymorphism in AURKA is not associated with a modified risk of breast cancer in BRCA1 and BRCA2 carriers.