Structural Basis of Mycobacterium tuberculosis Transcription and Transcription Inhibition.

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis, which kills 1.8 million annually. Mtb RNA polymerase (RNAP) is the target of the first-line antituberculosis drug rifampin (Rif). We report crystal structures of Mtb RNAP, alone and in complex with Rif, at 3.8-4.4 Å resolution. The results identify an Mtb-specific structural module of Mtb RNAP and establish that Rif functions by a steric-occlusion mechanism that prevents extension of RNA. We also report non-Rif-related compounds-Nα-aroyl-N-aryl-phenylalaninamides (AAPs)-that potently and selectively inhibit Mtb RNAP and Mtb growth, and we report crystal structures of Mtb RNAP in complex with AAPs. AAPs bind to a different site on Mtb RNAP than Rif, exhibit no cross-resistance with Rif, function additively when co-administered with Rif, and suppress resistance emergence when co-administered with Rif.

Production of VP3-only virus-like particles of Adeno-associated virus 2 in E. coli cells.

Adeno-associated Virus (AAV) is a promising vector for gene therapy. However, few studies have focused on producing virus-like particles (VLPs) of AAV in cells, especially in E. coli. In this study, we describe a method to produce empty VP3-only VLPs of AAV2 in E. coli by co-expressing VP3 and assembly-activating protein (AAP) of AAV2. Although the yields of VLPs produced with our method were low, the VLPs were able to self-assemble in E. coli without the need of in vitro capsid assembly. The produced VLPs were characterized by immunological detection and transmission electron microscopy (TEM). In conclusion, this study demonstrated that capsid assembly of AAV2 is possible in E. coli, and E. coli may be a candidate system for production of VLPs of AAV.

Development and psychometric evaluation of the asthma Action plan questionnaire (AAPQ).

OBJECTIVE: To develop a practical and psychometrically sound tool to evaluate caregiver knowledge of their child's asthma action plan (AAP). METHODS: A pilot study was conducted in a sample of 40 caregivers of children with asthma to assess the content validity, item difficulty, and item discrimination of the Asthma Action Plan Questionnaire (AAPQ). The inter-rater and intra-rater agreement of the AAPQ's scoring rubric were also examined. Subsequently, a large-scale study was conducted in a sample of 80 caregivers of children with asthma and 40 caregivers of children without current asthma and no prior exposure to patients with asthma to evaluate the internal consistency, test-retest reliability, and known-groups validity of the AAPQ. RESULTS: The 7-item AAPQ demonstrated acceptable content validity (a scale-content validity index of 0.98) and internal consistency (Cronbach's alpha =.63 and mean inter-item correlation coefficient of.20) and very strong test-retest reliability over a two-to-four-week period (r = .88, p < .001). The AAPQ discriminated between caregivers of children with asthma and caregivers of children without asthma (M ± SD 8.3 ± 1.6 vs. 4.3 ± 1.7, p < .001, respectively). CONCLUSION: The AAPQ is a valid and reliable questionnaire that provides an assessment of caregivers' knowledge of their child's AAP and can guide educational interventions by healthcare providers.

TU-LESS procedure for acute abdomen in late pregnancy: a retrospective study.

BACKGROUND: Acute abdominal conditions during pregnancy are significant risks to maternal and fetal health, necessitating timely diagnosis and intervention. The choice of surgical approach is a major concern for obstetricians. OBJECTIVE: To evaluate the safety and efficacy of the TU-LESS procedure for acute abdomen in late pregnancy. METHODS: We retrospectively analyzed 12 patients who underwent TU-LESS for acute abdominal conditions in the third trimester from 2020 to 2023. We reviewed medical records for clinical characteristics, surgical interventions, postoperative complications, and pregnancy outcomes. RESULTS: The study included patients with a median age of 27 (range 20-35) and a BMI of 24.33 kg/m2 (range 21.34-31.96). The median gestational age at surgery was 30 weeks (range, 28 + 3-32 + 4 weeks), with surgeries lasting an average of 60 min (range, 30-163 min). Blood loss was 2-20 mL, and the median hospital stay post-surgery was 6 days (range, 2-16 days). There were no significant complications. The median time to delivery after TU-LESS was 56 days (range, 26-66 days), resulting in 8 full-term deliveries, 2 preterm cesareans, and 2 preterm vaginal deliveries. All newborns were healthy, with no fetal losses or neonatal deaths. CONCLUSION: TU-LESS, performed by experienced obstetricians and gynecologists with proper preoperative preparation, is safe and effective for managing acute abdomen in late pregnancy, without the need to delay surgery due to gestational age.

The Association of Maternal Periodontal Diseases in the Postpartum Period with Preterm Low Birth Weight.

AIM: Preterm birth is the most adverse effect of pregnancy, commonly leading to low birth weight. Our study aimed to assess the relationship between maternal periodontal status and adverse pregnancy outcomes by immediate postpartum periodontal examination and diagnosis. MATERIALS AND METHODS: 125 mothers were divided into four groups based on gestational day (GD) and newborns' birth weight (BW); the mothers with GD ≥ 259 days and BW ≥ 2500 gm (Control), the mothers with GD <259 days and BW ≥ 2500 gm (PT group), the mothers with GD ≥ 259 days and BW <2500 gm (LBW group), and the mothers with GD <259 days and BW <2500 gm (PT-LBW group). The maternal periodontal assessment was carried out within 3 days after delivery. RESULTS: The bleeding on probing (BOP) of the PT-LBW group was significantly higher than the control (P = 0.027). The correlation test revealed a mild inverse relationship between BOP and BW (R = -0.23, P = 0.044). According to the new 2018 American Academy of Periodontology (AAP) periodontal classification, there was no significant difference between periodontal status within groups. CONCLUSION: The present study suggests that BOP, an early sign of gingival inflammation, is involved in adverse pregnancy outcomes. CLINICAL SIGNIFICANCE: This study is the first of its kind to use immediate postpartum periodontal examination and diagnosis by the new 2018 AAP periodontal classification. The findings demonstrate that signs of gingival inflammation may be associated with adverse pregnancy outcomes. How to cite this article: Yanaranci S, Laosrisin N, Sriprasertsuk A, et al. The Association of Maternal Periodontal Diseases in the Postpartum Period with Preterm Low Birth Weight. J Contemp Dent Pract 2024;25(2):99-106.

Disruption of the amino acid transporter CsAAP2 inhibits auxin-mediated root development in cucumber.

Amino acid transporters are the principal mediators of organic nitrogen distribution within plants and are essential for plant growth and development. Despite this importance, relatively few amino acid transporter genes have been explored and elucidated in cucumber (Cucumis sativus). Here, a total of 86 amino acid transporter genes were identified in the cucumber genome. We further identified Amino Acid Permease (AAP) subfamily members that exhibited distinct expression patterns in different tissues. We found that the CsAAP2 as a candidate gene encoding a functional amino acid transporter is highly expressed in cucumber root vascular cells. CsAAP2 knockout lines exhibited arrested development of root meristem, which then caused the delayed initiation of lateral root and the inhibition of root elongation. What is more, the shoot growth of aap2 mutants was strongly retarded due to defects in cucumber root development. Moreover, aap2 mutants exhibited higher concentrations of amino acids and lignin in roots. We found that the mutant roots had a stronger ability to acidize medium. Furthermore, in the aap2 mutants, polar auxin transport was disrupted in the root tip, leading to high auxin levels in roots. Interestingly, slightly alkaline media rescued their severely reduced root growth by stimulating auxin pathway.

A Metagenomic and Amplicon Sequencing Combined Approach Reveals the Best Primers to Study Marine Aerobic Anoxygenic Phototrophs.

Studies based on protein-coding genes are essential to describe the diversity within bacterial functional groups. In the case of aerobic anoxygenic phototrophic (AAP) bacteria, the pufM gene has been established as the genetic marker for this particular functional group, although available primers are known to have amplification biases. We review here the existing primers for pufM gene amplification, design new ones, and evaluate their phylogenetic coverage. We then use samples from contrasting marine environments to evaluate their performance. By comparing the taxonomic composition of communities retrieved with metagenomics and with different amplicon approaches, we show that the commonly used PCR primers are biased towards the Gammaproteobacteria phylum and some Alphaproteobacteria clades. The metagenomic approach, as well as the use of other combinations of the existing and newly designed primers, show that these groups are in fact less abundant than previously observed, and that a great proportion of pufM sequences are affiliated to uncultured representatives, particularly in the open ocean. Altogether, the framework developed here becomes a better alternative for future studies based on the pufM gene and, additionally, serves as a reference for primer evaluation of other functional genes.

Prevalence of different stages of periodontal diseases among a sample of young adult obese Egyptian patients: a hospital based Cross-sectional study over 1 year.

BACKGROUND: This cross-sectional study aimed to determine the prevalence of different stages of periodontal diseases based on the recent classification in a sample of young adult obese Egyptian dental outpatients. METHODS: This study included 314 patients seeking dental treatment at the Diagnostic Center of the Dental hospital, Faculty of Dentistry, Cairo University. Validated oral health questionnaire for adults regarding their age, gender, level of education and oral health routines as well as oral health impact profile questionnaire for chronic periodontitis (OHIP-CP) were filled by all patients. Obesity parameters were also assessed through person's weight in kilograms, height in centimeters and waist circumference to determine the obesity stage. Diagnosis was made based on measurements of clinical periodontal parameters including a full mouth plaque index (PI), bleeding on probing (BoP), pocket depth (PD), clinical attachment level (CAL) and gingival recession depth (RD). Radiographic examination was performed using periapical radiographs. Ordinal logistic regression analysis was used to determine significant predictors of periodontal diseases and discriminant analysis was performed to predict periodontal disease classification.  RESULTS: The age range in the study sample was 19-39 years old. The prevalence of different stages of periodontal diseases was 100%. Gingivitis was the most prevalent periodontal disease (63.7%) followed by Periodontitis Stage III (22.6%) then Stage II (11.1%). Stage I showed the least prevalence (2.5%). An increase in BMI was statistically associated with an increase in PD, CAL, RD, PI and vice versa (P-value < 0.05). The total OHIP-CP was 15.99 ± 3.06 for all participants. CONCLUSIONS: There was a statistically significant association between periodontal diseases and obesity in young adults, as well as a statistically significant direct correlation between BMI and periodontal parameters. Self-assessment of oral health and obesity were significant predictors of periodontal disease. CLINICAL TRIAL REGISTRATION ID: NCT04618068.

Research on Multi-Sensor Fusion Indoor Fire Perception Algorithm Based on Improved TCN.

Indoor fires cause huge casualties and economic losses worldwide. Thus, it is critical to quickly and accurately perceive the fire. In this work, an indoor fire perception algorithm based on multi-sensor fusion was proposed. Firstly, the sensor data features were fully extracted by improved temporal convolutional network (TCN). Then, the dimension of the extracted features was reduced by adaptive average pooling (AAP). Finally, the fire classification was realized by the support vector machine (SVM) classifier. Experimental results demonstrated that the proposed algorithm can improve accuracy of fire classification by more than 2.5% and detection speed by more than 15%, compared with TCN, back propagation (BP) neural network and long short-term memory (LSTM). In conclusion, the proposed algorithm can perceive the fire quickly and accurately, which is of great significance to improve the performance of the current fire prediction systems.

AFM Identifies a Protein Complex Involved in Pathogen Adhesion Which Ruptures at Three Nanonewtons.

Staphylococci bind to the blood protein von Willebrand Factor (vWF), thereby causing endovascular infections. Whether and how this interaction occurs with the medically important pathogen Staphylococcus epidermidis is unknown. Using single-molecule experiments, we demonstrate that the S. epidermidis protein Aap binds vWF via an ultrastrong force, ∼3 nN, the strongest noncovalent biological bond ever reported, and we show that this interaction is activated by tensile loading, suggesting a catch-bond behavior. Aap-vWF binding involves exclusively the A1 domain of vWF but requires both the A and B domains of Aap, as revealed by inhibition assays using specific monoclonal antibodies. Collectively, our results point to a mechanism where force-induced unfolding of the B repeats activates the A domain of Aap, shifting it from a weak- to a strong-binding state, which then engages into an ultrastrong interaction with vWF A1. This shear-dependent function of Aap offers promise for innovative antistaphylococcal therapies.

Effects of Auricularia auricula Polysaccharides on Gut Microbiota Composition in Type 2 Diabetic Mice.

In previous studies, Auriculariaauricula polysaccharides (AAP) has been found to improve type 2 diabetes mellitus, but its mechanism remains unclear. In this study, we sought to demonstrate that AAP achieves remission by altering the gut microbiota in mice with type 2 diabetes. We successfully constructed a type 2 diabetes mellitus (T2DM) model induced by a high-fat diet (HFD) combined with streptozotocin (STZ), following which fasting blood glucose (FBG) levels and oral glucose tolerance test (OTGG) were observed to decrease significantly after 5 weeks of AAP intervention. Furthermore, AAP enhanced the activities of total superoxide dismutase (T-SOD), catalase (CAT), and glutathione peroxidase (GSH-Px), and reduced the content of malondialdehyde (MDA) to alleviate the oxidative stress injury. AAP-M (200 mg/kg/d) displayed the best improvement effect. Moreover, 16S rRNA results showed that AAP decreased the abundance of Firmicutes and increased that of Bacteroidetes. The abundance of beneficial genera such as Faecalibaculum, Dubosiella, Alloprevotella, and those belonging to the family Lachnospiraceae was increased due to the intake of AAP. AAP could reduced the abundance of Desulfovibrio, Enterorhabdus, and Helicobacter. In all, these results suggest that AAP can improve the disorders of glucose and lipid metabolism by regulating the structure of the gut microbiota.

[Attachment Representations and Burnout of Social Workers]. / Zu Bindungsrepräsentationen und Burnout bei sozialpädagogischen Fachpersonen.

This paper examines the distribution of attachment representations among social work professionals using the Adult Attachment Projective Picture System (AAP; George, West, Pettem, 1997). In this sample, the influence of attachment on the occurrence of burnout syndrome is investigated, as this is considered as a trigger for further mental and physical illnesses. For this purpose, 79 social pedagogical professionals from the German-speaking part of Switzerland were examined over four time points using the Burnout Screening Scales - BOSS. The following distribution of attachment representations was found using the AAP: 25.3 % secure, 38.0 % insecure dismissing, 27.8 % insecure preoccupied, and 8.9 % unresolved trauma. This distribution differs significantly from other samples of non-clinical adults and psychotherapists. Interestingly, no general associations emerged between insecure attachment representations and burnout. A significant positive correlation was shown between "unresolved trauma" and the suspected diagnosis of "burnout occupation". The so far few but contradictory empirical findings on attachment representations among professionals require further research activities as well as an intensive sensitization with regard to attachment theory in basic and further training courses and a further establishment of self-awareness and supervision components in all psychosocial fields of work.

High-grade astrocytoma with piloid features (HGAP): the Charité experience with a new central nervous system tumor entity.

PURPOSE: High-grade astrocytoma with piloid features (HGAP) is a recently described brain tumor entity defined by a specific DNA methylation profile. HGAP has been proposed to be integrated in the upcoming World Health Organization classification of central nervous system tumors expected in 2021. In this series, we present the first single-center experience with this new entity. METHODS: During 2017 and 2020, six HGAP were identified. Clinical course, surgical procedure, histopathology, genome-wide DNA methylation analysis, imaging, and adjuvant therapy were collected. RESULTS: Tumors were localized in the brain stem (n = 1), cerebellar peduncle (n = 1), diencephalon (n = 1), mesencephalon (n = 1), cerebrum (n = 1) and the thoracic spinal cord (n = 2). The lesions typically presented as T1w hypo- to isointense and T2w hyperintense with inhomogeneous contrast enhancement on MRI. All patients underwent initial surgical intervention. Three patients received adjuvant radiochemotherapy, and one patient adjuvant radiotherapy alone. Four patients died of disease, with an overall survival of 1.8, 9.1, 14.8 and 18.1 months. One patient was alive at the time of last follow-up, 14.6 months after surgery, and one patient was lost to follow-up. Apart from one tumor, the lesions did not present with high grade histology, however patients showed poor clinical outcomes. CONCLUSIONS: Here, we provide detailed clinical, neuroradiological, histological, and molecular pathological information which might aid in clinical decision making until larger case series are published. With the exception of one case, the tumors did not present with high-grade histology but patients still showed short intervals between diagnosis and tumor progression or death even after extensive multimodal therapy.

The NRP 8th Edition: Innovation in Education.

The American Academy of Pediatrics/American Heart Association Neonatal Resuscitation Program® (NRP®) 8th-Edition materials were released in June 2021 and must be in use by January 1, 2022. Ongoing international review and consensus of resuscitation science since 2015 has yielded no major changes in practice. However, the NRP Steering Committee revised several practices in the interest of patient safety and educational efficiency. The NRP 8th Edition offers NRP Essentials and NRP Advanced levels of learning and 2 recommended Provider Course formats. In most hospitals, NRP Essentials and NRP Advanced will be taught using instructor-led Provider Courses. Resuscitation Quality Improvement® (RQI® for NRP®), a self-directed learning program that uses low-dose, high-frequency quarterly learning and skills sessions, may be used in hospitals that already use RQI for life support education.

Improving Self-Efficacy of Student Asthma Management in Elementary and Preschool Staff.

Asthma is a leading cause of chronic illness among school-aged children and adolescents. Current trends have led to school faculty and staff becoming increasingly responsible for managing student asthma, often without optimal training or resources. The purpose of this project was to establish whether facilitated access to personalized student asthma action plans (AAPs), education, proper use, and school nurse support improved reported self-efficacy regarding student asthma exacerbation prevention and management in elementary and preschool faculty and staff. Thirty-five participants from an urban, underserved Connecticut school were surveyed to determine perceived self-efficacy regarding student asthma exacerbation prevention and management. AAPs were then placed with students' asthma inhalers, and all participants were instructed on their use. Three months later, participants were resurveyed. A statistically significant difference after both the initial education and 3-month survey was identified. Providing elementary and preschool faculty and staff with facilitated access to student action plans and education on their use can improve perceived self-efficacy regarding student asthma exacerbation prevention and management.

Evolutionary significance of amino acid permease transporters in 17 plants from Chlorophyta to Angiospermae.

BACKGROUND: Nitrogen is an indispensable nutrient for plant growth. It is used and transported in the form of amino acids in living organisms. Transporting amino acids to various parts of plants requires relevant transport proteins, such as amino acid permeases (AAPs), which were our focus in this study. RESULTS: We found that 5 AAP genes were present in Chlorophyte species and more AAP genes were predicted in Bryophyta and Lycophytes. Two main groups were defined and group I comprised 5 clades. Our phylogenetic analysis indicated that the origin of clades 2, 3, and 4 is Gymnospermae and that these clades are closely related. The members of clade 1 included Chlorophyta to Gymnospermae. Group II, as a new branch consisting of non-seed plants, is first proposed in our research. Our results also indicated that the AAP family was already present in Chlorophyta and then expanded accompanying the development of vasculature. Concurrently, the AAP family experienced multiple duplication events that promoted the generation of new functions and differentiation of sub-functions. CONCLUSIONS: Our findings suggest that the AAP gene originated in Chlorophyta, and some non-seed AAP genes clustered in one group. A second group, which contained plants of all evolutionary stages, indicated the evolution of AAPs. These new findings can be used to guide future research.

Residues on Adeno-associated Virus Capsid Lumen Dictate Interactions and Compatibility with the Assembly-Activating Protein.

The adeno-associated virus (AAV) serves as a broadly used vector system for in vivo gene delivery. The process of AAV capsid assembly remains poorly understood. The viral cofactor assembly-activating protein (AAP) is required for maximum AAV production and has multiple roles in capsid assembly, namely, trafficking of the structural proteins (VP) to the nuclear site of assembly, promoting the stability of VP against multiple degradation pathways, and facilitating stable interactions between VP monomers. The N-terminal 60 amino acids of AAP (AAPN) are essential for these functions. Presumably, AAP must physically interact with VP to execute its multiple functions, but the molecular nature of the AAP-VP interaction is not well understood. Here, we query how structurally related AAVs functionally engage AAP from AAV serotype 2 (AAP2) toward virion assembly. These studies led to the identification of key residues on the lumenal capsid surface that are important for AAP-VP and for VP-VP interactions. Replacing a cluster of glutamic acid residues with a glutamine-rich motif on the conserved VP beta-barrel structure of variants incompatible with AAP2 creates a gain-of-function mutant compatible with AAP2. Conversely, mutating positively charged residues within the hydrophobic region of AAP2 and conserved core domains within AAPN creates a gain-of-function AAP2 mutant that rescues assembly of the incompatible variant. Our results suggest a model for capsid assembly where surface charge/neutrality dictates an interaction between AAPN and the lumenal VP surface to nucleate capsid assembly.IMPORTANCE Efforts to engineer the AAV capsid to gain desirable properties for gene therapy (e.g., tropism, reduced immunogenicity, and higher potency) require that capsid modifications do not affect particle assembly. The relationship between VP and the cofactor that facilitates its assembly, AAP, is central to both assembly preservation and vector production. Understanding the requirements for this compatibility can inform manufacturing strategies to maximize production and reduce costs. Additionally, library-based approaches that simultaneously examine a large number of capsid variants would benefit from a universally functional AAP, which could hedge against overlooking variants with potentially valuable phenotypes that were lost during vector library production due to incompatibility with the cognate AAP. Studying interactions between the structural and nonstructural components of AAV enhances our fundamental knowledge of capsid assembly mechanisms and the protein-protein interactions required for productive assembly of the icosahedral capsid.

The histomolecular criteria established for adult anaplastic pilocytic astrocytoma are not applicable to the pediatric population.

Pilocytic astrocytoma (PA) is the most common pediatric glioma, arising from a single driver MAPK pathway alteration. Classified as a grade I tumor according to the 2016 WHO classification, prognosis is excellent with a 10-year survival rate > 95% after surgery. However, rare cases present with anaplastic features, including an unexpected high mitotic/proliferative index, thus posing a diagnostic and therapeutic challenge. Based on small histomolecular series and case reports, such tumors arising at the time of diagnosis or recurrence have been designated by many names including pilocytic astrocytoma with anaplastic features (PAAF). Recent DNA methylation-profiling studies performed mainly on adult cases have revealed that PAAF exhibit a specific methylation signature, thus constituting a distinct methylation class from typical PA [methylation class anaplastic astrocytoma with piloid features-(MC-AAP)]. However, the diagnostic and prognostic significance of MC-AAP remains to be determined in children. We performed an integrative work on the largest pediatric cohort of PAAF, defined according to strict criteria: morphology compatible with the diagnosis of PA, with or without necrosis, ≥ 4 mitoses for 2.3 mm2, and MAPK pathway alteration. We subjected 31 tumors to clinical, imaging, morphological and molecular analyses, including DNA methylation profiling. We identified only one tumor belonging to the MC-AAP (3%), the others exhibiting a methylation profile typical for PA (77%), IDH-wild-type glioblastoma (7%), and diffuse leptomeningeal glioneuronal tumor (3%), while three cases (10%) did not match to a known DNA methylation class. No significant outcome differences were observed between PAAF with necrosis versus no necrosis (p = 0.07), or with 4-6 mitoses versus 7 or more mitoses (p = 0.857). Our findings argue that the diagnostic histomolecular criteria established for anaplasia in adult PA are not of diagnostic or prognostic value in a pediatric setting. Further extensive and comprehensive integrative studies are necessary to accurately define this exceptional entity in children.

Short and Long Term Exposure to Ambient Air Pollution and Impact on Health in India: A Systematic Review.

Health effects attributable to short-term and long-term ambient air pollution (AAP) exposure in Indian population are less understood. This study evaluates the effect of short time and long-term exposure to AAP on respiratory morbidity, mortality and premature mortality for the exposed population. A total of 59 studies are reviewed to examine the effects of short-term exposure (n = 23); long-term exposure (n = 18) and premature mortality (n = 18). Short-term exposures to ambient pollutants have strong associations between COPD, respiratory illnesses and higher rates of hospital admission or visit. The long-term effects of AAP, associated with deficit lung function, asthma, heart attack, cardiovascular mortality and premature mortality have received much attention. Particulate matter (PM2.5 and PM10) is primarily responsible for respiratory health problems. Out of 18 literature reviewed on premature mortality, most (12 of 18) studies have statistically significant associations between AAP exposure and increased premature mortality risk.

Biofilm-associated accumulation-associated protein (Aap): A contributing factor to the predominant growth of Staphylococcus epidermidis in platelet concentrates.

BACKGROUND AND OBJECTIVES: Staphylococcus epidermidis is a predominant contaminant of platelet concentrates (PCs), outcompeting other skin flora bacteria such as Staphylococcus capitis. The accumulation-associated protein (Aap), encoded by the aap gene, is involved in formation of bacterial aggregates (biofilms) in S. epidermidis and is absent in S. capitis. In this study, the role of S. epidermidis aap in enhancing biofilm formation and conferring an advantageous growth in PCs was investigated. MATERIALS AND METHODS: Biofilm formation assays of S. epidermidis 1457, S. epidermidis 1457∆aap, S. capitis 517 and S. capitis 517 carrying S. epidermidis aap (S. capitis 517/pRBaap) were performed in glucose-supplemented trypticase soy broth (TSBg) and PCs. Additionally, competition assays with paired cultures (1:1 ratio) of S. epidermidis and S. capitis strains were seeded in PCs, followed by determination of viable counts of each organism at the end of PC storage. RESULTS: Staphylococcus epidermidis aap had no effect on biofilm formation in TSBg. By contrast in PCs, S. epidermidis 1457 showed higher biofilm formation than S. epidermidis 1457∆aap (P < 0·05). Biofilm formation was also enhanced in S. capitis 517/pRBaap compared to S. capitis 517 (P = 0·054). Competition assays showed that S. epidermidis 1457 outcompeted S. capitis 517, and importantly, S. capitis 517/pRBaap outcompeted S. capitis 517 and S. epidermidis 1457∆aap. CONCLUSION: This study demonstrated that S. epidermidis aap plays a role in biofilm formation in PCs conferring an advantageous proliferation to skin flora bacteria in this milieu. The molecular mechanisms of action of Aap merit further investigation.