Measuring Equity in Readmission as a Distinct Assessment of Hospital Performance

Importance

Equity is an essential domain of health care quality. The Centers for Medicare & Medicaid Services (CMS) developed 2 Disparity Methods that together assess equity in clinical outcomes.

Objectives

To define a measure of equitable readmissions; identify hospitals with equitable readmissions by insurance (dual eligible vs non-dual eligible) or patient race (Black vs White); and compare hospitals with and without equitable readmissions by hospital characteristics and performance on accountability measures (quality, cost, and value).

Design, Setting, and Participants

Cross-sectional study of US hospitals eligible for the CMS Hospital-Wide Readmission measure using Medicare data from July 2018 through June 2019.

Main Outcomes and Measures

We created a definition of equitable readmissions using CMS Disparity Methods, which evaluate hospitals on 2 methods: outcomes for populations at risk for disparities (across-hospital method); and disparities in care within hospitals' patient populations (within-a-single-hospital method).

Exposures

Hospital patient demographics; hospital characteristics; and 3 measures of hospital performance-quality, cost, and value (quality relative to cost).

Results

Of 4638 hospitals, 74% served a sufficient number of dual-eligible patients, and 42% served a sufficient number of Black patients to apply CMS Disparity Methods by insurance and race. Of eligible hospitals, 17% had equitable readmission rates by insurance and 30% by race. Hospitals with equitable readmissions by insurance or race cared for a lower percentage of Black patients (insurance, 1.9% [IQR, 0.2%-8.8%] vs 3.3% [IQR, 0.7%-10.8%], P < .01; race, 7.6% [IQR, 3.2%-16.6%] vs 9.3% [IQR, 4.0%-19.0%], P = .01), and differed from nonequitable hospitals in multiple domains (teaching status, geography, size; P < .01). In examining equity by insurance, hospitals with low costs were more likely to have equitable readmissions (odds ratio, 1.57 [95% CI, 1.38-1.77), and there was no relationship between quality and value, and equity. In examining equity by race, hospitals with high overall quality were more likely to have equitable readmissions (odds ratio, 1.14 [95% CI, 1.03-1.26]), and there was no relationship between cost and value, and equity.

Conclusion and Relevance

A minority of hospitals achieved equitable readmissions. Notably, hospitals with equitable readmissions were characteristically different from those without. For example, hospitals with equitable readmissions served fewer Black patients, reinforcing the role of structural racism in hospital-level inequities. Implementation of an equitable readmission measure must consider unequal distribution of at-risk patients among hospitals.

Pediatric Mental Health Emergencies During 5 COVID-19 Waves in New York City

OBJECTIVES

To describe the proportion of pediatric mental health emergency department (MH-ED) visits across 5 COVID-19 waves in New York City (NYC) and to examine the relationship between MH-ED visits, COVID-19 prevalence, and societal restrictions.

METHODS

We conducted a time-series analysis of MH-ED visits among patients ages 5 to 17 years using the INSIGHT Clinical Research Network, a database from 5 medical centers in NYC from January 1, 2016, to June 12, 2022. We estimated seasonally adjusted changes in MH-ED visit rates during the COVID-19 pandemic, compared with predicted prepandemic levels, specific to each COVID-19 wave and stratified by mental health diagnoses and sociodemographic characteristics. We estimated associations between MH-ED visit rates, COVID-19 prevalence, and societal restrictions measured by the Stringency Index.

RESULTS

Of 686 500 ED visits in the cohort, 27 168 (4.0%) were MH-ED visits. The proportion of MH-ED visits was higher during each COVID-19 wave compared with predicted prepandemic trends. Increased MH-ED visits were seen for eating disorders across all waves; anxiety disorders in all except wave 3; depressive disorders and suicidality/self-harm in wave 2; and substance use disorders in waves 2, 4, and 5. MH-ED visits were increased from expected among female, adolescent, Asian race, high Child Opportunity Index patients. There was no association between MH-ED visits and NYC COVID-19 prevalence or NY State Stringency Index.

CONCLUSIONS

The proportion of pediatric MH-ED visits during the COVID-19 pandemic was higher during each wave compared with the predicted prepandemic period, with varied increases among diagnostic and sociodemographic subgroups. Enhanced pediatric mental health resources are essential to address these findings.

Chronic Medication Burden After Cardiac Surgery for Pediatric Medicaid Beneficiaries

BACKGROUND

Congenital heart defects are the most common and resource-intensive birth defects. As children with congenital heart defects increasingly survive beyond early childhood, it is imperative to understand longitudinal disease burden.

OBJECTIVES

The purpose of this study was to examine chronic outpatient prescription medication use and expenditures for New York State pediatric Medicaid enrollees, comparing children who undergo cardiac surgery (cardiac enrollees) and the general pediatric population.

METHODS

This was a retrospective cohort study of all Medicaid enrollees age <18 years using the New York State Congenital Heart Surgery Collaborative for Longitudinal Outcomes and Utilization of Resources database (2006-2019). Primary outcomes were total chronic medications per person-year, enrollees per 100 person-years using ≥1 and ≥3 medications, and medication expenditures per person-year. We described and compared outcomes between cardiac enrollees and the general pediatric population. Among cardiac enrollees, multivariable regression examined associations between outcomes and clinical characteristics.

RESULTS

We included 5,459 unique children (32,131 person-years) who underwent cardiac surgery and 4.5 million children (22 million person-years) who did not. More than 4 in 10 children who underwent cardiac surgery used ≥1 chronic medication compared with approximately 1 in 10 children who did not have cardiac surgery. Medication expenditures were 10 times higher per person-year for cardiac compared with noncardiac enrollees. Among cardiac enrollees, disease severity was associated with chronic medication use; use was highest among infants; however, nearly one-half of adolescents used ≥1 chronic medication.

CONCLUSIONS

Children who undergo cardiac surgery experience high medication burden that persists throughout childhood. Understanding chronic medication use can inform clinicians (both pediatricians and subspecialists) and policymakers, and ultimately the value of care for this medically complex population.

Characterizing Racial Disparities in Emergency Department Pediatric Physical Restraint by Sex and Age

This cross-sectional study evaluates racial disparities in physical restraint use in US emergency departments.

Psychotropic Medication Use in United States Pediatric Emergency Department Visits

OBJECTIVE AND BACKGROUND

Little is known about pediatric psychotropic medication use in the emergency department (ED), despite a rise in mental and behavioral health visits. This study describes psychotropic medication use in a nationally representative sample of pediatric mental and behavioral health ED visits over a 14-year period.

METHODS

We conducted a cross-sectional analysis of pediatric (6-17 years) mental and behavioral health ED visits using the National Hospital Ambulatory Medical Care Survey, 2006-2019. We describe administration of psychotropic medications by medication type, diagnosis, and over time. Using multivariable survey-weighted logistic regression, we examine associations between medication administration and sociodemographics.

RESULTS

A psychotropic medication was administered in 11.4% of the estimated 11,792,860 pediatric mental and behavioral health ED visits in our sample. Benzodiazepines were administered most frequently (4.9% of visits). Visits with anxiety disorders had the highest frequency of psychotropic medication use (26.7%). Visits by Black non-Hispanic patients had a 60% decreased odds of medication administration compared to visits for White non-Hispanic patients. Visits with public compared to private insurance had a 3.5 times increased odds of psychotropic polypharmacy. The proportion of visits in which a psychotropic medication was administered did not change statistically over time.

CONCLUSIONS

A psychotropic medication was administered in 1 in 10 pediatric mental and behavioral health ED visits. Use differed by sociodemographics but did not change over time. As more youth seek mental and behavioral health care in the ED, we must better understand appropriate medication use to ensure quality and equitable care.

Structural Racism in Behavioral Health Presentation and Management

Nia is a first-grade student with a history of trauma who was brought in by ambulance to the pediatric emergency department for "out of control behavior" at school. This is the first of multiple presentations to the emergency department for psychiatric evaluation, stabilization, and management throughout her elementary and middle school years. Several of the visits resulted in admission to the inpatient pediatric service, where she "boarded" while awaiting transfer to an inpatient psychiatric facility. At times, clinical teams used involuntary emergency medications and physical restraints, as well as hospital security presence at the bedside, to control Nia's behavior. Nia is Black and her story is a case study of how structural racism manifests for an individual child. Her story highlights the impact of adultification bias and the propensity to mislabel Black youth with diagnoses characterized by fixed patterns of negative behaviors, as opposed to recognizing normative reactions to trauma or other adverse childhood experiences-in Nia's case, poverty, domestic violence, and Child Protective Services involvement. In telling Nia's story, we (1) define racism and discuss the interplay of structural, institutional, and interpersonal racism in the health care, education, and judicial systems; (2) highlight the impact of adultification bias on Black youth; (3) delineate racial disparities in behavioral health diagnosis and management, school discipline and exclusion, and health care's contributions to the school-to-prison pipeline; and finally (4) propose action steps to mitigate the impact of racism on pediatric mental health and health care.

Follow-up After Pediatric Mental Health Emergency Visits

OBJECTIVES

To examine how outpatient mental health (MH) follow-up after a pediatric MH emergency department (ED) discharge varies by patient characteristics and to evaluate the association between timely follow-up and return encounters.

METHODS

We conducted a retrospective study of 28 551 children aged 6 to 17 years with MH ED discharges from January 2018 to June 2019, using the IBM Watson MarketScan Medicaid database. Odds of nonemergent outpatient follow-up, adjusted for sociodemographic and clinical characteristics, were estimated using logistic regression. Cox proportional hazard models were used to evaluate the association between timely follow-up and risk of return MH acute care encounters (ED visits and hospitalizations).

RESULTS

Following MH ED discharge, 31.2% and 55.8% of children had an outpatient MH visit within 7 and 30 days, respectively. The return rate was 26.5% within 6 months. Compared with children with no past-year outpatient MH visits, those with ≥14 past-year MH visits had 9.53 odds of accessing follow-up care within 30 days (95% confidence interval [CI], 8.75-10.38). Timely follow-up within 30 days was associated with a 26% decreased risk of return within 5 days of the index ED discharge (hazard ratio, 0.74; 95% CI, 0.63-0.91), followed by an increased risk of return thereafter.

CONCLUSIONS

Connection to outpatient care within 7 and 30 days of a MH ED discharge remains poor, and children without prior MH outpatient care are at highest risk for poor access to care. Interventions to link to outpatient MH care should prioritize follow-up within 5 days of an MH ED discharge.

Pediatric mental health visits with prolonged length of stay in community emergency departments during COVID-19

Objectives

To characterize trends in pediatric mental health visit counts, including visits for prolonged length of stay (LOS), in a sample of emergency departments (EDs) from 29 states during COVID-19.

Methods

We performed a secondary analysis of the Clinical Emergency Data Registry from January 2020 through December 2021. We reported trends in pediatric mental health visit counts overall and for those with prolonged ED LOS. We reported incident rate ratios (IRRs) for monthly counts compared to January 2020. Among visits with LOS >24 hours, we reported on the most common diagnostic categories.

Results

There were 107 EDs from 29 states with available complete data in 2020 and 2021. Pediatric mental health visit counts resulting in a LOS greater than 6, 12, and 24 hours were higher for much of 2021. At their peak, there were 604 visits with LOS >12 hours (IRR, 2.14; 95% confidence interval [CI], 1.86-2.47) and 262 visits (IRR, 2.46; 95% CI, 1.97-3.09) with LOS >24 hours in April 2021. Pediatric mental health visits with LOS >12 hours and >24 hours made up 20.9% and 7.3% of pediatric mental health visits overall, respectively. For visits with ED LOS >24 hours, the most common diagnostic categories were suicide or self-injury, depressive disorders, and mental health syndrome.

Conclusions

In this sample of 107 EDs in 29 states, visit counts with prolonged LOS >24 hours more than doubled in some months since the arrival of COVID-19. These findings are indicative of an increasingly strained emergency and mental health system.

Indications for Hospitalization in Children with SARS-CoV-2 Infection during the Omicron Wave in New York City

The emergence of the Omicron variant was accompanied by an acute increase in COVID-19 cases and hospitalizations in New York City. An increased incidence of COVID-19-associated croup in children during the Omicron wave has been recognized, suggesting that there may be other changes in clinical symptoms and severity. To better understand clinical outcomes and health care utilization in children infected with SARS-CoV-2 during the Omicron wave, we performed a cross-sectional study in pediatric patients aged ≤18 years who were tested for SARS-CoV-2 in pediatric emergency departments within a large medical system in New York City from 2 December 2021 to 23 January 2022. We described the clinical characteristics and outcomes of pediatric patients who presented to the pediatric emergency department and were hospitalized with SARS-CoV-2 infection during the Omicron wave in New York City. There were 2515 children tested in the ED for SARS-CoV-2 of whom 794 (31.6%) tested positive. Fifty-eight children were hospitalized for a COVID-19-related indication, representing 7.3% of all COVID-19-positive children and 72% of hospitalized COVID-19-positive children. Most (64%) children hospitalized for a COVID-19-related indication were less than 5 years old. Indications for hospitalization included respiratory symptoms, clinical monitoring of patients with comorbid conditions, and exacerbations of underlying disease. Eleven (19%) hospitalized children were admitted to the ICU and six (10%) required mechanical ventilation. Children infected with COVID-19 during the Omicron wave, particularly those less than 5 years old, were at risk for hospitalization. A majority of hospitalizations were directly related to COVID-19 infection although clinical indications varied with less than a half being admitted for respiratory diseases including croup. Our findings underscore the need for an effective COVID-19 vaccine in those less than 5 years old, continued monitoring for changes in clinical outcomes and health care utilization in children as more SARS-CoV-2 variants emerge, and understanding that children are often admitted for non-respiratory diseases with COVID-19.

Equitable and Timely Care of Febrile Neonates: A Cross-Sectional Study

OBJECTIVES

In pediatric emergency departments (EDs), racial/ethnic minorities are less likely to receive needed and timely care; however, clinical protocols have the potential to mitigate disparities. Neonatal fever management is protocolized in many EDs, but the timeliness to antibiotic administration is likely variable. We investigated the timeliness of antibiotic administration for febrile neonates and whether timeliness was associated with patients' race/ethnicity.

METHODS

Retrospective cross-sectional study of febrile neonates evaluated in one pediatric ED that uses an evidence-based guideline for the management of neonatal fever between March 2010 and December 2015. Primary outcome was time from ED arrival to antibiotic administration. Analysis of variance tests compared mean time with antibiotic administration across race/ethnicity. Multivariable linear regression investigated racial/ethnic differences in time to antibiotic administration after adjusting for patient demographics, timing of visit, the number of physicians involved, and ED census.

RESULTS

We evaluated 317 febrile neonates. Of the 269 patients with racial/ethnic data (84.9%), 54% were white non-Hispanic, 13% were black non-Hispanic, and 23% were Hispanic. The mean time to antibiotic administration was 204 minutes (range = 51-601 minutes). There was no significant association between patient race/ethnicity and time to first antibiotic administration. Emergency department census was significantly associated with timeliness.

CONCLUSIONS

There was a 10-hour range in the time to antibiotic administration for febrile neonates; however, variability in timeliness did not differ by race or ethnicity. This study demonstrates the need to further examine the role of protocols in mitigating disparities as well as factors that influence timeliness in antibiotic administration to febrile neonates.

Racial and Ethnic Disparities in Physical Restraint Use for Pediatric Patients in the Emergency Department

This cross-sectional study explores the use of physical restraint on youth at risk of harming themselves or others in the emergency department, stratified by race and ethnicity.

Racial disparities in the SOFA score among patients hospitalized with COVID-19

BACKGROUND

Sequential Organ Failure Assessment (SOFA) score predicts probability of in-hospital mortality. Many crisis standards of care suggest the use of SOFA scores to allocate medical resources during the COVID-19 pandemic.

RESEARCH QUESTION

Are SOFA scores elevated among Non-Hispanic Black and Hispanic patients hospitalized with COVID-19, compared to Non-Hispanic White patients?

STUDY DESIGN AND METHODS

Retrospective cohort study conducted in Yale New Haven Health System, including 5 hospitals with total of 2681 beds. Study population drawn from consecutive patients aged ≥18 admitted with COVID-19 from March 29th to August 1st, 2020. Patients excluded from the analysis if not their first admission with COVID-19, if they did not have SOFA score recorded within 24 hours of admission, if race and ethnicity data were not Non-Hispanic Black, Non-Hispanic White, or Hispanic, or if they had other missing data. The primary outcome was SOFA score, with peak score within 24 hours of admission dichotomized as <6 or ≥6.

RESULTS

Of 2982 patients admitted with COVID-19, 2320 met inclusion criteria and were analyzed, of whom 1058 (45.6%) were Non-Hispanic White, 645 (27.8%) were Hispanic, and 617 (26.6%) were Non-Hispanic Black. Median age was 65.0 and 1226 (52.8%) were female. In univariate logistic screen and in full multivariate model, Non-Hispanic Black patients but not Hispanic patients had greater odds of an elevated SOFA score ≥6 when compared to Non-Hispanic White patients (OR 1.49, 95%CI 1.11-1.99).

INTERPRETATION

Given current unequal patterns in social determinants of health, US crisis standards of care utilizing the SOFA score to allocate medical resources would be more likely to deny these resources to Non-Hispanic Black patients.

The potential impact of triage protocols on racial disparities in clinical outcomes among COVID-positive patients in a large academic healthcare system

BACKGROUND

The COVID-19 pandemic has had a devastating impact in the United States, particularly for Black populations, and has heavily burdened the healthcare system. Hospitals have created protocols to allocate limited resources, but there is concern that these protocols will exacerbate disparities. The sequential organ failure assessment (SOFA) score is a tool often used in triage protocols. In these protocols, patients with higher SOFA scores are denied resources based on the assumption that they have worse clinical outcomes. The purpose of this study was to assess whether using SOFA score as a triage tool among COVID-positive patients would exacerbate racial disparities in clinical outcomes.

METHODS

We analyzed data from a retrospective cohort of hospitalized COVID-positive patients in the Yale-New Haven Health System. We examined associations between race/ethnicity and peak overall/24-hour SOFA score, in-hospital mortality, and ICU admission. Other predictors of interest were age, sex, primary language, and insurance status. We used one-way ANOVA and chi-square tests to assess differences in SOFA score across racial/ethnic groups and linear and logistic regression to assess differences in clinical outcomes by sociodemographic characteristics.

RESULTS

Our final sample included 2,554 patients. Black patients had higher SOFA scores compared to patients of other races. However, Black patients did not have significantly greater in-hospital mortality or ICU admission compared to patients of other races.

CONCLUSION

While Black patients in this sample of hospitalized COVID-positive patients had higher SOFA scores compared to patients of other races, this did not translate to higher in-hospital mortality or ICU admission. Results demonstrate that if SOFA score had been used to allocate care, Black COVID patients would have been denied care despite having similar clinical outcomes to white patients. Therefore, using SOFA score to allocate resources has the potential to exacerbate racial inequities by disproportionately denying care to Black patients and should not be used to determine access to care. Healthcare systems must develop and use COVID-19 triage protocols that prioritize equity.

Prolonged Emergency Department Length of Stay for US Pediatric Mental Health Visits (2005-2015)

BACKGROUND AND OBJECTIVES

Children seeking care in the emergency department (ED) for mental health conditions are at risk for prolonged length of stay (LOS). A more contemporary description of trends and visit characteristics associated with prolonged ED LOS at the national level is lacking in the literature. Our objectives were to (1) compare LOS trends for pediatric mental health versus non-mental health ED visits and (2) explore patient-level characteristics associated with prolonged LOS for mental health ED visits.

METHODS

We conducted an observational analysis of ED visits among children 6 to 17 years of age using the National Hospital Ambulatory Medical Care Survey (2005-2015). We assessed trends in rates of prolonged LOS and the association between prolonged LOS and demographic and clinical characteristics (race and ethnicity, payer type, and presence of a concurrent physical health diagnosis) using descriptive statistics and survey-weighted logistic regression.

RESULTS

From 2005 to 2015, rates of prolonged LOS for pediatric mental health ED visits increased over time from 16.3% to 24.6% (LOS >6 hours) and 5.3% to 12.7% (LOS >12 hours), in contrast to non-mental health visits for which LOS remained stable. For mental health visits, Hispanic ethnicity was associated with an almost threefold odds of LOS >12 hours (odds ratio 2.74; 95% confidence interval 1.69-4.44); there was no difference in LOS by payer type.

CONCLUSIONS

The substantial rise in prolonged LOS for mental health ED visits and disparity for Hispanic children suggest worsening and inequitable access to definitive pediatric mental health care. Policy makers and health systems should work to provide equitable and timely access to pediatric mental health care.

Health Equity Rounds: An Interdisciplinary Case Conference to Address Implicit Bias and Structural Racism for Faculty and Trainees

INTRODUCTION

The medical community recognizes the importance of confronting structural racism and implicit bias to address health inequities. Several curricula aimed at teaching trainees about these issues are described in the literature. However, few curricula exist that engage faculty members as learners rather than teachers of these topics or target interdisciplinary audiences.

METHODS

We developed a longitudinal case conference curriculum called Health Equity Rounds (HER) to discuss and address the impact of structural racism and implicit bias on patient care. The curriculum engaged participants across training levels and disciplines on these topics utilizing case-based discussion, evidence-based exercises, and two relevant conceptual frameworks. It was delivered quarterly as part of a departmental case conference series. We evaluated HER's feasibility and acceptability by tracking conference attendance and administering postconference surveys. We analyzed quantitative survey data using descriptive statistics and qualitatively reviewed free-text comments.

RESULTS

We delivered seven 1-hour HER conferences at our institution from June 2016 to June 2018. A mean of 66 participants attended each HER. Most survey respondents (88% or more) indicated that HER promoted personal reflection on implicit bias, and 75% or more indicated that HER would impact their clinical practice.

DISCUSSION

HER provided a unique forum for practitioners across training levels to address structural racism and implicit bias. Our aim in dissemination is to provide meaningful tools for others to adapt at their own institutions, recognizing that HER should serve as a component of larger, multifaceted efforts to decrease structural racism and implicit bias in health care.

Molecular characterisation of Haemophilus influenzae type a and untypeable strains isolated simultaneously from cerebrospinal fluid and blood: novel use of quantitative real-time PCR based on the cap copy number to determine virulence

This study investigated the genetic structure of the cap region of an isolate of Haemophilus influenzae serotype a (Hia) from the cerebrospinal fluid (CSF) of a child with meningitis. In addition, the genetic structure of the cap region of a non-serotypeable H. influenzae isolate, obtained simultaneously from the blood of the same patient, was determined. According to restriction fragment length polymorphism analysis, the CSF and blood isolates were identical, with the exception of a single band shift of c. 35 kb. PCR analyses suggested that the CSF isolate possessed the IS1016-bexA gene and cap region II, whereas the blood isolate only had the IS1016 element. Furthermore, Southern analysis of DNA from both isolates showed that the CSF isolate carried the cap gene(s), while the blood isolate did not. Using a novel quantitative real-time PCR approach for determining the cap copy number, it was demonstrated that the CSF isolate had two intact tandem repeats of the cap gene containing three copies of IS1016, whereas the blood isolate had only one copy of IS1016. This study provided evidence that H. influenzae serotypes other than serotype b can cause serious disease, and that the virulence of these non-serotype b strains relates primarily to the cap gene copy number and the structure of the cap locus. Therefore, the quantitative real-time PCR assay described in this study should be useful for the rapid and definitive identification of strains of H. influenzae type a that represent a risk for serious disease.

Inducible macrolide resistance in Corynebacterium jeikeium

Corynebacterium jeikeium is an opportunistic pathogen primarily of immunocompromised (neutropenic) patients. Broad-spectrum resistance to antimicrobial agents is a common feature of C. jeikeium clinical isolates. We studied the profiles of susceptibility of 20 clinical strains of C. jeikeium to a range of antimicrobial agents. The strains were separated into two groups depending on the susceptibility to erythromycin (ERY), with one group (17 strains) representing resistant organisms (MIC > 128 microg/ml) and the second group (3 strains) representing susceptible organisms (MIC < or = 0.25 microg/ml). The ERY resistance crossed to other members of the macrolide-lincosamide-streptogramin B (MLSb) group. Furthermore, this resistance was inducible with MLSb agents but not non-MLSb agents. Expression of ERY resistance was linked to the presence of an allele of the class X erm genes, erm(X)cj, with >93% identity to other erm genes of this class. Our evidence indicates that erm(X)cj is integrated within the chromosome, which contrasts with previous reports for the plasmid-associated erm(X) genes found in C. diphtheriae and C. xerosis. In 40% of C. jeikeium strains, erm(X)cj is present within the transposon, Tn5432. However, in the remaining strains, the components of Tn5432 (i.e., the erm and transposase genes) have separated within the chromosome. The rearrangement of Tn5432 leads to the possibility that the other drug resistance genes have become included in a new composite transposon bound by the IS1249 elements.

Effect of drug concentration on emergence of macrolide resistance in Mycobacterium avium

The emergence of antibiotic resistance in mycobacteria involves the selection of mutant variants within a susceptible bacterial population. However, it is unclear whether antimycobacterial drugs act just as selective agents or can influence the rate of appearance of resistant mutants. The present study was initiated to address this issue by monitoring the effects of antimicrobial agents on the appearance and growth of clarithromycin (CLR)-resistant (CLR(r)) bacilli in broth cultures of Mycobacterium avium. Preexposure of M. avium to CLR had a significant dose effect on the emergence of resistance, with concentrations of 4 to 8 microg/ml resulting in a maximal (approximately 10(4)-fold) increase in the number of CLR(r) bacilli after a 4-day incubation. In addition, a dose effect was found with azithromycin. The use of combinations of CLR with either ethambutol (EMB) or rifabutin (RFB) resulted in fewer resistant bacilli compared to the use of CLR alone. The lowest active concentration of EMB (4 microg/ml) was equivalent to the EMB MIC (4 to 8 microg/ml) for the parental CLR(s) strain and the emergent CLR(r) variants, and thus, the antiresistance effect was probably the result of the bacteriostatic effect of EMB on CLR(r) bacilli. However, RFB was an order of magnitude more active (0.05 microg/ml) at reducing resistance than suggested by the MIC of this agent (0.5 to 1 microg/ml). These results indicate that the emergence of resistance was not simply the selection of a preexisting subpopulation of resistant bacilli. Further analysis suggested that early events in the emergence of resistance involved organisms (progenitors) that acquired a resistance phenotype. In addition, the progenitors appeared to be in a transient state, able to develop into a stable resistant lineage in the presence of CLR, or able to revert to the wild type in nonselective conditions.

Setting up a CLIA-certified laboratory in a student health services clinic

Performing some laboratory tests on site at a student health service clinic may increase efficiency and cut costs for patients. However, with the passage of the Clinical Laboratory Improvement Amendments (CLIA) of 1988, many laboratories in physician offices and clinics have shut down because of increased regulatory requirements. The personnel in one SHS laboratory found that the guidelines proposed by CLIA help assure quality care and are not prohibitive. In this article, the process of applying for and receiving a CLIA certificate in the student health clinic setting is explored.

Detection of rifampin resistance in Mycobacterium tuberculosis by use of a rapid, simple, and specific RNA/RNA mismatch assay

An adaption of an RNA/RNA duplex, base pair-mismatch assay is capable of detecting rifampin resistance in Mycobacterium tuberculosis. The specificity and sensitivity of the mismatch assay in detecting rifampin resistance were 100% and 96%, respectively, when tested against 46 rifampin-resistant and rifampin-susceptible strains of M. tuberculosis. By use of a range of mycobacterial and nonmycobacterial prokaryote pathogens, the mismatch assay was shown to be specific for M. tuberculosis and Mycobacterium bovis. The assay is cost-effective compared with DNA sequencing and other molecular methods and is simple to perform and interpret. Furthermore, the assay can return a result within 24 h after receipt of an isolated organism and potentially can be used directly with smear-positive specimens.

Effect of ethambutol on emergence of clarithromycin-resistant Mycobacterium avium complex in the beige mouse model

An animal model was developed for studying macrolide-resistant Mycobacterium avium complex (MAC) and to measure the effect of ethambutol on resistance. MAC-infected beige mice were given clarithromycin daily; the frequency of clarithromycin-resistant MAC after 8 and 12 weeks was 10(-3) and 10(-2), respectively. Combined ethambutol plus clarithromycin did not increase anti-MAC activity, but clarithromycin-resistant MAC was less frequent (P < .05). The frequency of clarithromycin-resistant MAC in mice receiving the combination was significantly higher than that in untreated mice. These results are consistent with two human trials, which showed that adding ethambutol reduced the frequency of clarithromycin-resistant MAC. Results of the present study suggest that with an initially high level of MAC infection, the addition of ethambutol may only delay resistance. This mouse test system will be useful for investigating the influence of the level of MAC infection and the effect of other drugs on the frequency of resistant MAC.

Rapid detection of mutations associated with macrolide resistance in Mycobacterium avium complex

Macrolide resistance in Mycobacterium avium can be detected with an adaption of a commercially available RNA/RNA duplex mismatch assay (Ambion, Austin, Tex.). The sensitivity and specificity values for the assay were 100% when evaluated against 41 macrolide-resistant and -susceptible strains of M. avium. Resistant subpopulations of approximately 20% could be readily detected. The assay is simple to perform and interpret, inexpensive, and rapid (< 24-h turnaround).

Genetic basis of macrolide resistance in Mycobacterium avium isolated from patients with disseminated disease

Clarithromycin (CLM) and azithromycin (AZM) are important agents in the treatment of disseminated Mycobacterium avium complex disease; however, monotherapy with these macrolides often leads to clinically significant resistance. The underlying resistance mechanism was investigated by comparing 23S rRNA gene sequences in the domain V region of 10 CLM-susceptible strains included in this study. The only differences in the domain V sequences associated with CLM resistance were at position 2274 of the complete M. avium 23S rRNA gene (GenBank accession no. X74494). All the CLM-susceptible strains had an A residue at this site, whereas seven of the eight CLM-resistant strains had either a C, G, or T. Four of these seven CLM-resistant strains emerged during monotherapy with CLM and two emerged during AZM monotherapy, showing that resistance selected by either macrolide was associated with mutation of the 23S rRNA gene. Thermodynamic analysis of secondary rRNA structure suggests that the observed mutations cause an alteration in free energy associated with rRNA folding, which may result in a localized conformation change in assembled ribosomes. Such a shift may be important in the resistance of ribosomes to the effects of macrolides. This study therefore establishes a link between mutations within the 23S rRNA gene and clinically significant macrolide resistance in M. avium and also identifies a possible molecular mechanism of resistance at the level of the ribosome.

Internal controls as performance monitors and quantitative standards in the detection by polymerase chain reaction of herpes simplex virus and cytomegalovirus in clinical specimens

Internal controls (IC) were produced and characterized for an HSV and a CMV PCR assay which serve both as test performance monitors and as quantitative standards. In each of the PCR assays the IC and native targets were amplified with equal efficiency and were detected with the same sensitivity, i.e. < 10 target copies. An algorithm was developed for the use of IC as a quantitative standard which entailed coamplifying a test specimen with four two-fold dilutions of the respective IC target (63-500 copies), followed by regression analysis of the relative yield of amplification products. This approach allowed the determination of both the initial virus genome copy number and the variability of the results, which provided a confidence index for the PCR assay. The relative yields of PCR products were determined by Southern blot and probe hybridization and by densitometry of digitized ethidium bromide-stained gels. Both methods produced estimations of the initial target copy numbers within +/- 40% of the expected value. Such a comprehensive analysis of an internal control for a PCR assay provides a rigorous control of test performance and permits reliable quantitative interpretation of a PCR assay result.

T cell function in children with acute lymphoblastic leukaemia

Modern intensive chemotherapy has dramatically improved the prognosis of acute lymphoblastic leukaemia (ALL) in children. However, once remission has been established, quality of life and even survival may be threatened by exacerbation of viral infections in the prolonged period of continuation therapy necessary to prevent relapse. Often the viruses involved in the most severe infections are from the herpesvirus and paramyxovirus groups, suggesting that patients suffer from a defect in the cellular immunity thought essential to control such cell-associated infections. This may result from a T cell defect and, in this study, T cell responsiveness of patients under therapy for leukaemia has been investigated. In vitro proliferative responses of peripheral blood leucocytes (PBL) to the T cell mitogen phytohaemagglutinin (PHA) were impaired in children with ALL before treatment and in the induction of remission. Impairment was attributable to reduced T cell numbers, the presence of inhibitors in the patient's serum and direct damage to lymphocytes. On achieving remission, proliferative responses to PHA of both CD4+ and CD8+ T cell subsets quickly returned to normal levels with the switch to continuation chemotherapy. Proliferative responses to Herpes simplex virus antigens were also apparently normal in the majority of patients tested in remission. Further investigations, however, have suggested a persisting defect in CD8+ lymphocyte function. Gamma interferon secretion by PHA-stimulated PBLs was severely reduced for children with ALL in remission when compared with control children of similar age. Further, cytotoxic T lymphocyte responses to allogeneic cells could only be induced in PBL isolated from two of 13 children in remission from ALL whilst all control children of similar age and adults produced anti-allogeneic responses.

Induction of oncofetal antigen-specific suppressor pathways, involving Thy-1+ cells, during the early stages of tumor progression

The early stages of tumor progression were modelled by intraperitoneally injecting BALB/c mice daily with exponentially increasing numbers of mitomycin C-treated, syngeneic MPC-11 tumor cells. At various stages of this regime, mesenteric lymph node (MLN) and spleen cells were assessed for regulatory activity on the induction of cytotoxic T lymphocytes (CTL) in vitro. Cells present in both MLN and spleens of mice whose daily tumor dose had reached 102,400 MPC-11 cells impaired the generation of CTL specific for MPC-11 and specific for oncofetal antigen(s) shared between MPC-11 and Day 14-15 syngeneic fetal liver cells. Depletion of Thy-1+ cells from the regulatory cell populations removed the suppressive activity. The regulatory cells did not affect the induction of CTL specific for H-2b antigens in the context of H-2d (i.e., BALB/c) class I MHC.

Effect of opsonization on oxidative metabolism of plaice (Pleuronectes platessa L.) neutrophils

The effect of serum opsonization on Vibrio alginolyticus (heat-killed)-stimulated chemiluminescence (CL) by plaice kidney- and peritoneal exudate-derived neutrophils was investigated. Peritoneal neutrophils only recognized heat-labile and kidney neutrophils only heat-stable opsonic activity in normal serum. Specific antibody did not show opsonic activity nor any synergism with the normal serum opsonins for either neutrophil population. Evidence was found for the production, by plaice neutrophils, of H2O2, O2-, OH. and two or more, as yet unidentified, reactive oxygen species (ROS).

Migration of fish leucocytes in vitro: the effect of factors which may be involved in mediating inflammation

Plaice (Pleuronectes platessa L.) neutrophils were isolated from the kidney on a discontinuous Percoll gradient and from the peritoneal cavity at the peak of a glycogen-elicited inflammatory response. The migratory ability of neutrophils was assessed using a 48-well microchemotaxis chamber, with an incubation of 1.5 h at 12 degrees C. The two neutrophil populations showed different responses to N-formylmethionyl-leucyl-phenylalanine (FMLP). Whereas kidney neutrophils only showed a significant enhancement of migration at 10(-7) M, inflammatory neutrophils exhibited a bimodal response, with one peak of migratory activity at 10(-9) M and a second at greater than 10(-6) M. Kidney neutrophils showed a consistent response with various concentrations of a 24 h culture supernatant of Vibrio alginolyticus. In every case increased migration was observed with 5-, 10- and 100-fold dilutions, with the latter two conditions producing a significant enhancement (p less than 0.01 and p less than 0.05 respectively). The undiluted and 2-fold diluted supernatant caused a decreased cell migration compared with control values. The supernatant from kidney neutrophils cultured with serum-opsonized, heat-killed V. alginolyticus produced greater migratory activity than neutrophils or the treated bacteria incubated alone (the controls). In each case, the enhanced activity of the supernatant was detectable by 1 h of incubation. By 4 h, the activity of the neutrophil/bacteria supernatant was significantly higher than that of the controls (p less than 0.01), but by 24 h had fallen to control levels. There was no evidence for a chemotactic response with FMLP, the bacterial supernatant or the neutrophil-derived factor and the responses were therefore assumed to be chemokinetic.