Understanding persistent bacterial lung infections: clinical implications informed by the biology of the microbiota and biofilms.

The infections found in chronic obstructive pulmonary disease, cystic fibrosis, and bronchiectasis share a number of clinical similarities, the most striking of which is bacterial persistence despite the use of antibiotics. These infections have been clinically described using culture-based methods usually performed on sputum samples, and treatment has been directed towards the bacteria found in this manner. Unfortunately the clinical response to antibiotics is frequently not predictable based on these cultures, and the role of these cultured organisms in disease progression has been debated. The past 20 years have seen a revolution in the techniques used to describe bacterial populations and their growth patterns. These techniques have revealed these persistent lung infections are vastly more complicated than described by traditional, and still widely relied upon, sputum cultures. A better understanding of the initiation and evolution of these infections, and better clinical tools to describe them, will dramatically alter the way patients are cared for. While clinical tests to more accurately describe these infections are not yet available, the better appreciation of these infections afforded by current science should enlighten practitioners as to the care of their patients with these diseases.

Determination of agmatine using isotope dilution UPLC-tandem mass spectrometry: application to the characterization of the arginine decarboxylase pathway in Pseudomonas aeruginosa.

A method has been developed for the direct determination of agmatine in bacterial culture supernatants using isotope dilution ultra performance liquid chromatography (UPLC)-tandem mass spectrometry (UPLC-MS/MS). Agmatine determination in bacterial supernatants is comprised of spiking culture or isolate supernatants with a fixed concentration of uniformly labeled (13)C5,(15)N4-agmatine (synthesized by decarboxylation of uniformly labeled (13)C6,(15)N4-arginine using arginine decarboxylase from Pseudomonas aeruginosa) as an internal standard, followed by derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBDF) to improve the reversed-phase chromatographic retention characteristics of agmatine, as well as the selectivity and sensitivity of UPLC-MS/MS detection of this amine in complex biologically derived mixtures. Intrasample precisions for measurement of agmatine in culture supernatants average 4.1% (relative standard deviation). Calibration curves are linear over the range 5 nM to 10 µM, and the detection limit is estimated at 1.5 nM. To demonstrate the utility of the method, agmatine levels in supernatants of overnight cultures of wild-type (UCBPP-PA14), as well as arginine decarboxylase and agmatine deiminase mutant strains of P. aeruginosa strain UCBPP-PA14 were measured. This method verified that the mutant strains are lacking the specific metabolic capabilities to produce and metabolize agmatine. In addition, measurement of agmatine in supernatants of a panel of clinical isolates from patients with cystic fibrosis revealed that three of the P. aeruginosa isolates hyper-secreted agmatine into the supernatant, hypothesized to be a result of a mutation in the aguA gene. Because agmatine has potential inflammatory activities in the lung, this phenotype may be a virulence factor for P. aeruginosa in the lung environment of cystic fibrosis patients.

Structure and function of OprD protein in Pseudomonas aeruginosa: from antibiotic resistance to novel therapies.

Pseudomonas aeruginosa (P. aeruginosa) is a common pathogen isolated from patients with nosocomial infections. Due to its intrinsic and acquired antimicrobial resistance, limited classes of antibiotics can be used for the treatment of infection with P. aeruginosa. Of these, the carbapenems are very important; however, the occurrence of carbapenem-resistant strains is gradually increasing over time. Deficiency of the outer membrane protein OprD confers P. aeruginosa a basal level of resistance to carbapenems, especially to imipenem. Functional studies have revealed that loops 2 and 3 in the OprD protein contain the entrance and/or binding sites for imipenem. Therefore, any mutation in loop 2 and/or loop 3 that causes conformational changes could result in carbapenem resistance. OprD is also a common channel for some amino acids and peptides, and competition with carbapenems through the channel may also occur. Furthermore, OprD is a highly regulated protein at transcriptional and post-transcriptional levels by some metals, small bioactive molecules, amino acids, and efflux pump regulators. Because of its hypermutability and highly regulated properties, OprD is thought to be the most prevalent mechanism for carbapenem resistance in P. aeruginosa. Developing new strategies to combat infection with carbapenem-resistant P. aeruginosa lacking OprD is an ongoing challenge.

Transition to adult dental care from a pediatric hospital dental home for patients with special health care needs.

AIMS: This study describes patients with complex Special Health Care Needs (SHCN) transitioning from a pediatric hospital clinic dental home to adult care and evaluates effectiveness of transition practices. METHODS AND RESULTS: Demographics, medical/behavioral complexity, and documentation of transition processes were collected for patients graduated from the service in 2018/2019. An invitation to complete a survey assessing transition was sent to patients/guardians ≥ 14 months after the final visit. Seventy-nine patients graduated and 94% required accommodation for SHCN: 47% medical, 42% medical + behavioral, and 5% behavioral only. Of 63 eligible patients/guardians, 29 completed surveys. While 90% of surveyed patients had established some/all adult medical care, only 41% completed a dental visit, and less than 28% established a dental home. Medical/behavioral complexity, payer, and time since graduation did not impact having a visit. CONCLUSIONS: This study found ineffectiveness of departmental protocol for transition to adult dental homes for patients with SHCN. Developing an optimal transition process is complex and will require collaboration of all stakeholders. Introducing transition in early teen years, tracking progress at subsequent visits, assessing patient readiness, summarizing history for receiving providers, and verifying transition are elements of medical transition programs that should be included in dental transitions.

Discovery of an operon that participates in agmatine metabolism and regulates biofilm formation in Pseudomonas aeruginosa.

Agmatine is the decarboxylation product of arginine and a number of bacteria have devoted enzymatic pathways for its metabolism. Pseudomonas aeruginosa harbours the aguBA operon that metabolizes agmatine to putrescine, which can be subsequently converted into other polyamines or shunted into the TCA cycle for energy production. We discovered an alternate agmatine operon in the P. aeruginosa strain PA14 named agu2ABCA' that contains two genes for agmatine deiminases (agu2A and agu2A'). This operon was found to be present in 25% of clinical P. aeruginosa isolates. Agu2A' contains a twin-arginine translocation signal at its N-terminus and site-directed mutagenesis and cell fractionation experiments confirmed this protein is secreted to the periplasm. Analysis of the agu2ABCA' promoter demonstrates that agmatine induces expression of the operon during the stationary phase of growth and during biofilm growth and agu2ABCA' provides only weak complementation of aguBA, which is induced during log phase. Biofilm assays of mutants of all three agmatine deiminase genes in PA14 revealed that deletion of agu2ABCA', specifically its secreted product Agu2A', reduces biofilm production of PA14 following addition of exogenous agmatine. Together, these findings reveal a novel role for the agu2ABCA' operon in the biofilm development of P. aeruginosa.

Inpatient dental consultations at a pediatric hospital: A single center 1-year review.

AIMS: Inpatient dental consultations done at a pediatric hospital in 2017 were analyzed to determine consult reasons, requesting departments, and patient characteristics. Findings were compared to a 2007 study from the hospital. METHODS AND RESULTS: Data were collected from medical records. Descriptive statistics and logistic regressions were calculated. In 2017, 300 consults were performed for 211 patients (1.8% of inpatients). hematology-oncology requested the most consults (63%). Evaluation prior to cancer treatment, cardiac surgery, or organ transplantation was the most common reason for consult requests (52%). Fifty-eight percent patients had a dental home; older patients were more likely to have a dental home (P < .001). Patients with a dental home were less likely to have caries (P = .047). Many patients with a dental home had caries (33% in 2007 and 29% in 2017); more patients without a dental home had caries (46% in 2007 and 38% in 2017). CONCLUSIONS: This study both supports the dental home concept and reveals that many children with a dental home have treatment needs. This indicates that medical providers should not equate having a dental home with having dental health and emphasizes the value of an in-hospital dental service to support the management of critically ill children.

Pseudomonas aeruginosa: host defence in lung diseases.

Lung infections caused by the opportunistic pathogen Pseudomonas aeruginosa can present as a spectrum of clinical entities from a rapidly fatal pneumonia in a neutropenic patient to a multi-decade bronchitis in patients with cystic fibrosis. P. aeruginosa is ubiquitous in our environment, and one of the most versatile pathogens studied, capable of infecting a number of diverse life forms and surviving harsh environmental factors. It is also able to quickly adapt to new environments, including the lung, where it orchestrates virulence factors to acquire necessary nutrients, and if necessary, turn them off to prevent immune recognition. Despite these capabilities, P. aeruginosa rarely infects healthy human lungs. This is secondary to a highly evolved host defence mechanism that efficiently removes inhaled or aspirated pseudomonads. Many arms of the respiratory host defence have been elucidated using P. aeruginosa as a model pathogen. Human infections with P. aeruginosa have demonstrated the importance of the mechanical barrier functions including mucus clearance, and the innate immune system, including the critical role of the neutrophilic response. As more models of persistent or biofilm P. aeruginosa infections are developed, the role of the adaptive immune response will likely become more evident. Understanding the pathogenesis of P. aeruginosa, and the respiratory host defence response to it has, and will continue to, lead to novel therapeutic strategies to help patients.

Body mass index of children with severe early childhood caries.

PURPOSE: The purpose of this retrospective case study was to describe the body mass index (BMI) of children with severe early childhood caries (5-ECC) receiving dental rehabilitation under general anesthesia. METHODS: Demographics, BMI percentile, decoyed, missing, or filled teeth (dmft), and the number of pulp-involved teeth were analyzed for 293 healthy 2- to 5-year-olds (mean = 47.2 months). Weight groups were assigned using current Centers for Disease Control (CDC) BMI-for-age and gender definitions. Descriptive statistics were calculated and multivariate analysis used to evaluate BMI's association with oral health measures. BMI distribution of the subjects was compared graphically and with the use of confidence intervals to a reference population with similar demographics. RESULTS: The distribution of subjects' BMI percentiles was: underweight=11l%; normal weight=67%; at risk for overweight=9%; and overweight=11%. The mean dmft was 11.8; BMI percentile did not correlate with dmft or the number of pulp-involved teeth. Significantly, more children in the sample were underweight than in the reference population (11% vs. 5%). CONCLUSION: In this sample of S-ECC children, the BMI percentile was not correlated with dmft or the number of pulp-involved teeth, even After adjusting for confounding factors. Thirty-two percent had unhealthy weights, as currently defined by the Centers for Disease Control and Prevention.

Agmatine accumulation by Pseudomonas aeruginosa clinical isolates confers antibiotic tolerance and dampens host inflammation.

PURPOSE: In the cystic fibrosis (CF) airways, Pseudomonas aeruginosa undergoes diverse physiological changes in response to inflammation, antibiotic pressure, oxidative stress and a dynamic bioavailable nutrient pool. These include loss-of-function mutations that result in reduced virulence, altered metabolism and other phenotypes that are thought to confer a selective advantage for long-term persistence. Recently, clinical isolates of P. aeruginosa that hyperproduce agmatine (decarboxylated arginine) were cultured from individuals with CF. Sputum concentrations of this metabolite were also shown to correlate with disease severity. This raised the question of whether agmatine accumulation might also confer a selective advantage for P. aeruginosa during chronic colonization of the lung. METHODOLOGY AND RESULTS: We screened a library of P. aeruginosa CF clinical isolates and found that ~5 % of subjects harboured isolates with an agmatine hyperproducing phenotype. Agmatine accumulation was a direct result of mutations in aguA, encoding the arginine deiminase that catalyses the conversion of agmatine into various polyamines. We also found that agmatine hyperproducing isolates (aguA-) had increased tolerance to the cationic antibiotics gentamicin, tobramycin and colistin relative to their chromosomally complemented strains (aguA+). Finally, we revealed that agmatine diminishes IL-8 production by airway epithelial cells in response to bacterial infection, with a consequent decrease in neutrophil recruitment to the murine airways in an acute pneumonia model. CONCLUSION: These data highlight a potential new role for bacterial-derived agmatine that may have important consequences for the long-term persistence of P. aeruginosa in the CF airways.

Parental attitudes regarding behavior guidance of dental patients with autism.

PURPOSES: The purposes of this study were to evaluate: (1) parents' ability to predict dental treatment cooperation by their autistic child; (2) behavior guidance techniques (BGTs) used during treatment; and (3) parental attitudes regarding basic and advanced BGTs. METHODS: Data were collected from 85 parent/autistic child pairs and their dentists using surveys and treatment records. RESULTS: Parents most accurately predicted if their child would permit an examination in the dental chair (> or = 88%) and would cooperate for radiographs (> or = 84%). BGTs utilized most often (> 50%) were positive verbal reinforcement (PVR), tell-show-do (TSD), mouthprops, and rewards. In general, basic BGTs were more acceptable (> 81%) than advanced BGTs (>54%). The most acceptable techniques (>90%) in order were: PVR, TSD, distraction, rewards, general anesthesia, hand-holding by parent, and mouth-props. When parents evaluated only BGTs used for their child, all BGTs, including a stabilization device, were highly acceptable (> 91%), except for staff restraint (74%). CONCLUSIONS: Parents were accurate in predicting cooperation for some procedures. The most acceptable and efficacious BGTs in order were: PVR, TSD, distraction, rewards, and hand-holding by parent. Parental perceptions of BGTs were influenced by whether or not they had been used for their child.

Characteristics of publicly insured children with high dental expenses.

BACKGROUND: Dental coverage is provided for all children with Medicaid in Washington State. The goal of this study was to illuminate the characteristics of a sample of Medicaid-enrolled children with high dental expenses. METHODS: Dental care utilization data for a 33-month period were obtained from Washington State's Medicaid database. For children, 0 to 6 years, these data were linked with a parent survey addressing oral health behaviors, knowledge, family history of caries, snacking patterns, and access to dental care. Children with dental expenses of $1,000 or more were classified as the "high-expense" group. Risk factors for the high-expense group were evaluated using multiple logistic regression. RESULTS: 345 children had at least one dental procedure including preventive and diagnostic care. Among these, 30 children (9 percent) incurred 64 percent of total dental expenses for the entire group. Parent perception of lack of dental coverage was associated with incurring high dental expenses. Children of Asian or Pacific Islander heritage were at disproportionately high risk compared to White children. Age of child and family history of caries were also associated with increased risk for high expenses. CONCLUSIONS: Not all low-income children on Medicaid are at high risk for caries. A combination of factors, including family history of caries and parent's perception of lack of dental insurance coverage, can potentially increase a child's likelihood for high-expense dental treatment. This study highlighted a small group of children with disproportionately high dental expenses. For some, earlier knowledge of coverage may have resulted in more timely access to preventive and diagnostic care, reducing the subsequent need for expensive restorative treatment.

Combining procedures under general anesthesia.

PURPOSE: The purpose of this study was to analyze cases in which dentistry was combined with other procedures during a single outpatient general anesthetic (GA) in a children's hospital. Financial and time savings were evaluated for a subgroup of combined care patients. METHODS: Records of 120 patients who received combined dental and one other procedure under GA were reviewed. All were treated as outpatients, and dental procedures were more than just radiographs. Descriptive statistics were calculated for: (1) patient characteristics; (2) procedures; (3) times for procedures; (4) anesthesia; (5) recovery; and (6) total time in hospital. Records of 18 patients with combined dentistry and extraction of third molars were compared to 36 patients receiving the same procedures during separate GAs to evaluate time and costs for combined vs separate procedures. RESULTS: Patients ranged from 2 to 21 years, and 98% had special health care needs. Oral surgery (41%) and otolaryngology (23%) were most frequently combined with dentistry. Estimated mean savings for patients receiving dentistry and third molar extractions in combination were 312 minutes and $2,177. CONCLUSIONS: Combining care offers an economical vehicle for providing medical and dental care to patients needing multiple procedures. Awareness of the efficiency of combined care may lead to more combinations of procedures when possible.

Cooperation predictors for dental patients with autism.

PURPOSE: This study evaluated potential predictors of cooperation during dental appointments for children with autism. METHODS: Data were collected from 108 parent/child pairs and their dentists. Questions included: (1) medical/dental history; (2)functional language; (3) personal hygiene skills; (4) academic setting; and (5) achievements. Behavior was scored using the Frankl scale. RESULTS: Subjects were 80 males and 28 females 2.7 to 19 years old with a mean age of 9.8 years. Frankl scores were 65% uncooperative (definitely negative or negative) and 35% cooperative (positive or definitely positive). Multiple factors predicted uncooperative behavior: (1) appointment type (P=.03); (2) concurrent medical diagnoses (P=.04); (3) nonverbal/minimal or echololic language (P=.005); (4) inability to understand language appropriate for age (P=.02); (5) inability to follow multistep instructions (P=.04); (6) parents providing most/all tooth-brushing (P=.004); (7) partially or not toilet trained at 4+ years (P=.02); (8) inability to sit for a haircut (P=.01); (9) attending special education (P<.001); and (10) inability to read at 6+ years (P<.001). CONCLUSIONS: Five questions readily answered by a caregiver may indicate a child's cooperative potential. Preappointment inquiry about toilet training, toothbrushing, haircuts, academic achievement and language can give the dentist insight into the child's ability to respond positively to behavior guidance techniques based on communication.

Utilization of a hospital for treatment of pediatric dental emergencies.

PURPOSE: The purpose of this study was to investigate dental emergencies treated at a hospital clinic and emergency department (ED) to: (1) analyze emergency types; (2) determine reasons for seeking hospital care; and (3) examine trends compared to previous studies from this institution. METHODS: Records of 2,683 emergencies from 1995 to 2003 were reviewed. Demographics, reason for seeking care, and treatment details were analyzed overall by emergency type and for subgroups of patients with severe early childhood caries (S-ECC) and patients referred from other EDs. RESULTS: Emergencies were: 51% trauma, 40% caries, and 9% "other" emergencies unrelated to trauma or caries. Common patient characteristics were: (1) young age; (2) non-Caucasian ethnicity; (3) Medicaid as payer; (4) no dentist; and (5) proximity to the hospital. Caries emergencies increased significantly over the study period (P = .008), and 22% had S-ECC. Patients referred from other EDs were: 11% of trauma patients who commonly required sutures and/or extractions; and 3% of caries patients, 82% with extraoral swelling. CONCLUSIONS: Characteristics of patients seeking hospital care for dental emergencies were: (1) young age; (2) non-Caucasian ethnicity; (3) Medicaid as payer; (4) no dentist; and (5) proximity to CHRMC. Use differed by ethnic groups: Caucasians presented mostly for trauma; African Americans presented equally for caries and trauma; and Hispanics and Asians presented primarily for caries. Access to care, caries, and severe early childhood caries remain significant problems despite multiple programs targeting children's' oral health in Washington State.

Reasons for repeat dental treatment under general anesthesia for the healthy child.

PURPOSE: This study investigated reasons a healthy child may need repeat dental treatment under general anesthesia (GA). METHODS: Experimental subjects were 23 healthy children who received dental treatment under GA twice; controls were 23 healthy children requiring a single dental treatment session under GA. Records review determined demographics, intraoperative information, diagnosis, and treatment provided. Parents of 11 subjects and 9 controls competed a questionnaire and were interviewed. RESULTS: Many factors differed between subject and control children. Common characteristics of children requiring repeat care under GA (subjects) were: (1) 100% percent caries involvement of maxillary central incisors at time of initial treatment; (2) majority of central incisors were nonrestorable; (3) still using nursing bottle at the time of GA; (4) child responsible for brushing own teeth; (5) poor cooperation in the medical and dental setting; (6) difficult personality as described by parent; (7) dysfunctional social situation; and (8) lack of follow-up dental care. Stainless steel crowns were the most successful restoration placed. CONCLUSIONS: A number of predictors were found to help identify high-risk children. Best outcomes following dental rehabilitation under GA may result from aggressive treatment of caries, active follow-up, and education of parents.

Parent satisfaction with emergency dental treatment at a children's hospital.

PURPOSE: This study evaluated parental satisfaction with emergency dental treatment. METHODS: One hundred twenty-two parents of children requiring emergency extraction of 1 or more primary teeth completed a survey designed to test the effect of provider, treatment, and demographic variables on parental satisfaction. RESULTS: Most parents (>80%) indicated satisfaction with the treatment provided. Parents were most satisfied with treatment during clinic hours, treatment provided by an attending pediatric dentist, and treatment provided by male dentists. Satisfaction was correlated with the clarity of the provider explanation. Explanations by male dentists were perceived most positively. Parents of children receiving molar extraction(s) were more satisfied than parents of children with incisor extraction(s). Satisfaction did not correlate with ethnicity of the parent or patient, parent education level, funding sources, or use of an immobilization device. Parents preferred sedation for behavior management of the emergency patient. CONCLUSIONS: To address the expectations and concerns of parents, dental professionals need to be attentive to the quality of dentist-parent communication and parental expectations during emergency services.

The arginine decarboxylase pathways of host and pathogen interact to impact inflammatory pathways in the lung.

The arginine decarboxylase pathway, which converts arginine to agmatine, is present in both humans and most bacterial pathogens. In humans agmatine is a neurotransmitter with affinities towards α2-adrenoreceptors, serotonin receptors, and may inhibit nitric oxide synthase. In bacteria agmatine serves as a precursor to polyamine synthesis and was recently shown to enhance biofilm development in some strains of the respiratory pathogen Pseudomonas aeruginosa. We determined agmatine is at the center of a competing metabolism in the human lung during airways infections and is influenced by the metabolic phenotypes of the infecting pathogens. Ultra performance liquid chromatography with mass spectrometry detection was used to measure agmatine in human sputum samples from patients with cystic fibrosis, spent supernatant from clinical sputum isolates, and from bronchoalvelolar lavage fluid from mice infected with P. aeruginosa agmatine mutants. Agmatine in human sputum peaks during illness, decreased with treatment and is positively correlated with inflammatory cytokines. Analysis of the agmatine metabolic phenotype in clinical sputum isolates revealed most deplete agmatine when grown in its presence; however a minority appeared to generate large amounts of agmatine presumably driving sputum agmatine to high levels. Agmatine exposure to inflammatory cells and in mice demonstrated its role as a direct immune activator with effects on TNF-α production, likely through NF-κB activation. P. aeruginosa mutants for agmatine detection and metabolism were constructed and show the real-time evolution of host-derived agmatine in the airways during acute lung infection. These experiments also demonstrated pathogen agmatine production can upregulate the inflammatory response. As some clinical isolates have adapted to hypersecrete agmatine, these combined data would suggest agmatine is a novel target for immune modulation in the host-pathogen dynamic.

A one-year survey of inpatient dental consultations at a children's hospital.

This study describes dental consultations for pediatric inpatients. Records of inpatient dental consultations in 2007 were analyzed to determine consultation reasons, diagnoses, treatment, and demographics. Consultations from Hematology-Oncology (Hem-Onc) and Transplant Oncology (T-Onc) were further analyzed. One hundred and fifty-five consultations were performed for 133 subjects. Hem-Onc (37%) and T-Onc (17%) were the most frequent consultations. Requests were most frequently for baseline evaluation (33%) and oral pain/discomfort (10%). Frequent dental diagnoses were soft tissue conditions (29%) and caries (23%). A dental home preexisted for 48% of subjects and in 44% of consultations with caries and 53% without caries. Caries was present in 30% of consultations where Medicaid was sole payer versus 18% with non-Medicaid payers. Subjects from the Oncology department had more baseline evaluations, frequently had soft tissue diagnoses, and more often received preventive counseling and treatment under general anesthesia. In conclusion, dentists play an important role in optimal management of certain hospital inpatients.

Sonic tooth brushing reduces gingival overgrowth in renal transplant recipients.

Cyclosporine (CSA) is a commonly used immunosuppressive medication in pediatric transplantation. Drug-induced gingival overgrowth (DIGO) is a frequent side effect associated with CSA use and can impair the patient's ability to achieve good oral hygiene. This study tested the hypothesis that sonic tooth brushing and oral hygiene instruction can reduce the occurrence or severity of DIGO in CSA-treated pediatric renal transplant recipients. Twenty-three pediatric renal transplant patients with DIGO were randomly allocated to treatment or control groups. The treatment group received oral hygiene instruction and use of a sonic toothbrush, while the control group continued their usual home care with manual brushes. Dental impressions and photographs of all subjects were taken at baseline and every 3 months for a year. The casts and photographs were evaluated by a dental panel to compare the DIGO levels from baseline until the end of the study. After 12 months the control group had significantly more severe DIGO than did the sonic tooth brushing and oral hygiene instruction group (OR=4.5, 95%CI=1.2-16.0, P=0.03). Of the risk factors considered, only male gender was significantly associated with worse outcome (OR=6.1, 95%CI=2.3-16.1, P=0.03). The use of a powered toothbrush, together with oral hygiene instruction, may be an important component of health maintenance for pediatric transplant patients on CSA.