Taking stock of infections and antibiotic resistance in the elderly and long-term care facilities: A survey of existing and upcoming challenges

The twin challenges of longevity and climate change in controlling antimicrobial resistance

Antimicrobial resistance (AMR) is one of the global health challenges of the 21st century that is faced with the twin threats of global climate change and greater longevity, which pose a synergistic risk to the management of AMR. Antimicrobial agents are in high demand due to the challenges faced by increasing life expectancy and the dynamic changes in disease ecology prompted by climate change. In light of global aging and climate change, the complexity and importance of addressing antibiotic resistance are further highlighted by this interplay of issues.

Epidemiological, Microbiological, and Clinical Characteristics of Multi-Resistant Pseudomonas aeruginosa Isolates in King Fahad Medical City, Riyadh, Saudi Arabia

Increasing rates of serious multi-drug resistant (MDR) Pseudomonas aeruginosa infections have been reported globally, including in Saudi Arabia. This retrospective study investigates the epidemiological, microbiological, and clinical characteristics of multi-resistant P. aeruginosa (n3579 clinical isolates) in King Fahad Medical City, Riyadh, Saudi Arabia (2019–2021). Information on antimicrobial susceptibility and medical history was collected from the hospital database. P. aeruginosa infections occurred in 55.6% of males and 44.4% of females, and P. aeruginosa was more prevalent in children than in adults. Our analysis showed that P. aeruginosa had the highest sensitivity to amikacin (92.6%) and greatest resistance to aztreonam (29.8%), imipenem (29.5%), ceftazidime (26.1%), meropenem (25.6%), and cefepime (24.3%). MDR and extensively drug resistant (XDR) strains were more prevalent in male than female patients. Female patients showed higher rates of infection with pan-drug resistant (PDR) strains. Respiratory samples contained the majority of resistant isolates. Septic shock and liver disease were strongly correlated with mortality in the ICU patient group after analysing the relative risk associated with mortality. Our study emphasises the threat of multi-resistant P. aeruginosa in Saudi Arabia (and potentially the Middle East) and highlights important sources and contexts of infection that inhibit its effective control and clinical management.

Antibacterial-associated acute kidney injury among older adults: A post-marketing surveillance study using the FDA adverse events reporting system

PURPOSE

Antibacterials induce a differential risk of acute kidney injury (AKI) in older adults. This study investigated the reporting risk of AKI associated with antibacterials using the individual case safety reports (ICSRs) submitted to the Food and Drug Administration Adverse Event Reporting System (FAERS) database.

METHODS

A case/non-case method was used to assess AKI risk associated with antibacterials between 1 January 2000 and 30 September 2021. Cases were ICSRs for antibacterials with AKI as preferred terms included in the Medical Dictionary of Regulatory Activities (MedDRA) system organ classes 'Renal and urinary disorders' disorders. The analyses were completed on a de-duplicated data set containing only the recent version of the ICSR. Signals were defined by a lower 95% confidence interval (CI) of reporting odds ratio (ROR) ≥ 2, proportional reporting ratio (PRR) ≥ 2, information component (IC) > 0, Empirical Bayes Geometric Mean (EBGM) > 1 and reports ≥4. Sensitivity analyses were conducted a priori to assess the robustness of signals.

RESULTS

A total of 3 680 621 reports on ADEs were retrieved from FAERS over the study period, of which 92 194 were antibacterial reports. Gentamicin, sulfamethoxazole, trimethoprim and vancomycin consistently gave strong signals of disproportionality on all four disproportionality measures and across the different sensitivity analyses: gentamicin (ROR = 2.95[2.51-3.46]), sulfamethoxazole (ROR = 2.97[2.68-3.29]), trimethoprim (ROR = 2.81[2.29-3.46]) and vancomycin (ROR = 3.35[3.08-3.64]).

CONCLUSION

Signals for gentamicin, sulfamethoxazole, trimethoprim and vancomycin were confirmed by using antibacterials as a comparator, adjusting for drug-related competition bias and event-related competition bias.

Host gut resistome in Gulf War chronic multisymptom illness correlates with persistent inflammation

Chronic multisymptom illness (CMI) affects a subsection of elderly and war Veterans and is associated with systemic inflammation. Here, using a mouse model of CMI and a group of Gulf War (GW) Veterans' with CMI we show the presence of an altered host resistome. Results show that antibiotic resistance genes (ARGs) are significantly altered in the CMI group in both mice and GW Veterans when compared to control. Fecal samples from GW Veterans with persistent CMI show a significant increase of resistance to a wide class of antibiotics and exhibited an array of mobile genetic elements (MGEs) distinct from normal healthy controls. The altered resistome and gene signature is correlated with mouse serum IL-6 levels. Altered resistome in mice also is correlated strongly with intestinal inflammation, decreased synaptic plasticity, reversible with fecal microbiota transplant (FMT). The results reported might help in understanding the risks to treating hospital acquired infections in this population.

Antimicrobial-associated organ injury among the elderly: a systematic review and meta-analysis protocol

INTRODUCTION

Older adults (aged 65 years and above) constitute the fastest growing population cohort in the western world. There is increasing evidence that the burden of infections disproportionately affects this cohort of older adults and hence this vulnerable population is frequently exposed to antimicrobials. There is currently no systematic review summarising the evidence for risk of organ injury following antimicrobial exposure among older adults. This protocol will outline how we will conduct a systematic review and meta-analyses to examine the relationship between antimicrobial exposure and organ injury in older adults.

METHODS AND ANALYSIS

We will search for PsycINFO, PubMed and EMBASE databases for relevant articles using MeSH terms where applicable. After removing duplicates, articles will be screened for inclusion into or exclusion from the study by two reviewers. Title and abstract screening will be done first, followed by full-text screening. The Newcastle-Ottawa scale will be used to assess the risk of bias for cohort and case control studies, and the Cochrane collaboration's risk of bias tool will be used for randomised control trials. We will explore the potential sources of heterogeneity and bias using funnel and forest plots of the included studies.

ETHICS AND DISSEMINATION

During the conduct of the review, ethical principles will be observed to ensure integrity. Any potential conflicts of interests will be declared, all contributors acknowledged and no plagiarised material will be included in the review.The systematic review and meta-analysis will be submitted for publication in a peer-reviewed journal in geriatrics. The findings will also be presented at international conferences in geriatrics or pharmacoepidemiology. The results will be communicated to patient and public engagement networks supported by the NHS Research and Development.

PROSPERO REGISTRATION NUMBER

This protocol is registered in the PROSPERO database (registration number CRD42020152621).

Exploring temporal trends and risk factors for resistance in Escherichia coli-causing bacteraemia in England between 2013 and 2018: an ecological study

BACKGROUND

Escherichia coli are Gram-negative bacteria associated with an increasing burden of antimicrobial resistance (AMR) in England.

OBJECTIVES

To create a comprehensive epidemiological picture of E. coli bacteraemia resistance trends and risk factors in England by linking national microbiology data sources and performing a longitudinal analysis of rates.

METHODS

A retrospective observational study was conducted on all national records for antimicrobial susceptibility testing on E. coli bacteraemia in England from 1 January 2013 to 31 December 2018 from the UK Health Security Agency (UKHSA) and the BSAC Resistance Surveillance Programme (BSAC-RSP). Trends in AMR and MDR were estimated using iterative sequential regression. Logistic regression analyses were performed on UKHSA data to estimate the relationship between risk factors and AMR or MDR in E. coli bacteraemia isolates.

RESULTS

An increase in resistance rates was observed in community- and hospital-onset bacteraemia for third-generation cephalosporins, co-amoxiclav, gentamicin and ciprofloxacin. Among community-acquired cases, and after adjustment for other factors, patients aged >65 years were more likely to be infected by E. coli isolates resistant to at least one of 11 antibiotics than those aged 18-64 years (OR: 1.21, 95% CI: 1.18-1.25; P < 0.05). In hospital-onset cases, E. coli isolates from those aged 1-17 years were more likely to be resistant than those aged 18-64 years (OR: 1.33, 95% CI: 1.02-1.73; P < 0.05).

CONCLUSIONS

Antibiotic resistance rates in E. coli-causing bacteraemia increased between 2013 and 2018 in England for key antimicrobial agents. Findings of this study have implications for guiding future policies on a prescribing of antimicrobial agents, for specific patient populations in particular.

Risk of antimicrobial-associated organ injury among the older adults: a systematic review and meta-analysis

Background

Older adults (aged 65 years and above) constitute the fastest growing population cohort in the western world. There is increasing evidence that the burden of infections disproportionately affects older adults, and hence this vulnerable population is frequently exposed to antimicrobials. There is currently no systematic review summarising the evidence for organ injury risk among older adults following antimicrobial exposure. This systematic review and meta-analysis examined the relationship between antimicrobial exposure and organ injury in older adults.

Methodology

We searched for original research articles in PubMed, Embase.com, Web of Science core collection, Web of Science BIOSIS citation index, Scopus, Cochrane Central Register of Controlled Trials, ProQuest, and PsycINFO databases, using key words in titles and abstracts, and using MeSH terms. We searched for all available articles up to 31 May 2021. After removing duplicates, articles were screened for inclusion into or exclusion from the study by two reviewers. The Newcastle-Ottawa scale was used to assess the risk of bias for cohort and case-control studies. We explored the heterogeneity of the included studies using the Q test and I² test and the publication bias using the funnel plot and Egger’s test. The meta-analyses were performed using the OpenMetaAnalyst software.

Results

The overall absolute risks of acute kidney injury among older adults prescribed aminoglycosides, glycopeptides, and macrolides were 15.1% (95% CI: 12.8–17.3), 19.1% (95% CI: 15.4–22.7), and 0.3% (95% CI: 0.3–0.3), respectively. Only 3 studies reported antimicrobial associated drug-induced liver injury. Studies reporting on the association of organ injury and antimicrobial exposure by age or duration of treatment were too few to meta-analyse. The funnel plot and Egger’s tests did not indicate evidence of publication bias.

Conclusion

Older adults have a significantly higher risk of sustaining acute kidney injury when compared to the general adult population. Older adults prescribed aminoglycosides have a similar risk of acute kidney injury to the general adult population.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-021-02512-3.

Efficacy and safety of ceftobiprole in patients aged 65 years or older: a post hoc analysis of three Phase III studies

Aim: To evaluate the efficacy and safety of ceftobiprole in patients aged ≥65 years. Materials & methods: We conducted a post hoc analysis of three randomized, double-blind, Phase III studies in patients with acute bacterial skin and skin structure infections, community-acquired pneumonia and hospital-acquired pneumonia. Results: Findings for patients aged ≥65 years (n = 633) were consistent with those for the overall study populations, although a trend toward improved outcomes was reported in some subgroups, for example, patients aged ≥75 years with community-acquired pneumonia were more likely to achieve an early clinical response with ceftobiprole than comparator (treatment difference 16.3% [95% CI:1.8-30.8]). The safety profile was similar between treatment groups in all studies. Conclusion: This analysis further supports the efficacy and safety of ceftobiprole in older patients with acute bacterial skin and skin structure infections or pneumonia. Clinicaltrials.gov trial identifiers: NCT03137173, NCT00326287, NCT00210964, NCT00229008.

CuO(1-x)ZnO x nanocomposite with broad spectrum antibacterial activity: application in medical devices and acrylic paints

Inappropriate and disproportionate use of antibiotics have led to a rapid increase in antibacterial resistance. Therefore, alternative antibacterial strategies and solutions are sought to overcome any form of resistance to effectively treat and/or prevent the spread of infections. In this study, we report an eco-friendly and scalable approach to produce highly antibacterial CuO_(1-x)ZnO _x nanocomposite and its inclusion in medical devices and acrylic paint. Nanocomposite has nanoporous structure composed of primary nanocrystallites of Zn⁺² ion doped CuO (∼15 nm) phase and pure ZnO (∼10 nm) phase. Nanocomposite exhibit strong antibacterial activity against broad spectrum of bacteria relevant to the biomedical and food industries. At 100 ppm concentration and 2 h contact period, over 5 log reduction was observed against Escherichia coli, Listeria monocytogenes, Methicillin-resistant Staphylococcus aureus and Salmonella enterica Serovar Typhimurium. Nanocomposite incorporated in medical gauze, topical formulation, and acrylic paint exhibit over 4 log reduction against S. aureus. Bactericidal activity is governed by synergetic combination of electrostatic interaction of nanocomposite with bacterial cell envelope and simultaneous generation of reactive oxygen species. Results described here would be of great benefit in developing medical devices, coatings, and paints to eradicate the growth of a wide range of bacterial pathogens.

The ongoing challenge of vancomycin-resistant Enterococcus faecium and Enterococcus faecalis in Europe: an epidemiological analysis of bloodstream infections

Vancomycin-resistant enterococci infections are of great public health significance due to limited therapeutic options. We investigated epidemiological trends and risk factors of vancomycin resistance in enterococci isolates from patients with bloodstream infections in the EU/EEA from 2012 to 2018. Routine vancomycin susceptibility data of clinical E. faecium (n = 67,022) and E. faecalis (n = 103,112) blood isolates from the European Antimicrobial Resistance Surveillance Network were analysed using descriptive statistics and multivariable regression analyses. In Europe, proportions of vancomycin-resistant E. faecium (VREFm) increased from 8.1% (95%CI 6.7-9.7%) in 2012 to 19.0% (95%CI 16.8-21.5%) in 2018. Rising VREFm proportions were observed across all European regions, both genders and all age groups except children and adolescents (1-19 years). Adults (20-59 years) and elderly (≥60 years) had an increased likelihood of VREFm compared to children and adolescents (1-19 years) (OR: 1.99 [95%CI 1.42-2.79, p < 0.001] and OR: 1.56 [95%CI 1.09-2.23, p = 0.014], respectively). Inpatients hospital units, including internal medicine and ICUs, were associated with an increased likelihood of VREFm (OR: 2.29 (95%CI 1.58-3.32, p < 0.001) compared to the emergency department which reflects patients with community origin of E. faecium infections. The mean proportion of vancomycin-resistant E. faecalis in Europe was found to be low (1.1% [95%CI 0.9-1.4%]). Local and regional authorities should intensify efforts directed at diagnostic and antimicrobial stewardship for vancomycin and all last resort drugs for the management of VREFm, particularly for hospitalized elderly patients.

The epidemiology of carbapenem-non-susceptible Acinetobacter species in Europe: analysis of EARS-Net data from 2013 to 2017

BACKGROUND

Due to limited therapeutic options and their association with high mortality and morbidity, carbapenem-non-susceptible Acinetobacter spp. (CNA) are of significant public health importance. This study aimed to describe current epidemiological trends of CNA proportions in Europe and to identify factors that are associated with carbapenem non-susceptibility of isolates from patients with invasive Acinetobacter spp. infections.

METHODS

Data from routine carbapenem susceptibility testing of 18,412 invasive clinical Acinetobacter spp. isolates from 30 European countries in 2013-2017 were analysed using descriptive statistical analyses and uni- and multivariable regression analyses. These data were obtained from the European Antimicrobial Resistance Surveillance Network (EARS-Net).

RESULTS

The population-weighted mean proportion of carbapenem-non-susceptible Acinetobacter spp. in Europe is 35.6% (95% confidence interval [CI] 29.7-42.0%). With CNA proportions of 75.5% (95% CI 71.2-79.4%) and 71.5% (95% CI 66.7-75.9%) the burden of CNA is particularly high in Southern and Eastern European regions. In contrast, Northern and Western European regions recorded CNA proportions of 2.8% (95% CI 1.2-6.0%) and 6.3% (95% CI 4.5-8.9%), respectively. Population-weighted mean CNA proportions are especially high in Acinetobacter spp. isolates from intensive care units (54.0% [95% CI 47.6-60.3%]). Male gender, age above 20 years and ICU admission were identified as independent factors associated with an increased likelihood of CNA.

CONCLUSION

The burden of carbapenem-non-susceptible Acinetobacter spp. is particularly high in Southern and Eastern Europe. There is a risk that resistance could spread to other parts of Europe. Therefore, increased efforts in infection control and antibiotic stewardship, particularly in Intensive Care Units, are necessary to combat the spread of CNA in Europe.

Clinical predictors of descending necrotizing mediastinitis after deep neck infections

OBJECTIVES/HYPOTHESIS

To identify the clinical predictors of descending necrotizing mediastinitis (DNM) secondary to deep neck infections (DNIs) before treatment.

STUDY DESIGN

Retrospective case series.

METHODS

We reviewed 73 patients with DNIs who had been treated with external drainage at our institute between April 2009 and March 2019. We divided these patients into either a DNI group without mediastinitis (n = 55) or a DNM group secondary to DNI (n = 18). We collected clinical data and compared them between the groups, conducting univariate and multiple logistic regression analysis to identify the predictors of DNM.

RESULTS

We identified age, C-reactive protein (CRP), neutrophil percentage, lymphocyte percentage, neutrophil to lymphocyte ratio (NLR), presence of comorbidities, presence of gas, and abscess extension below the hyoid bone as statistically significant by univariate analysis. Moreover, multiple logistic regression analysis showed that age ≥55 years, NLR ≥13, and CRP ≥30 mg/dL were statistically significant.

CONCLUSIONS

We identified age ≥55, NLR ≥13, and CRP ≥30 before DNI treatment as clinical predictors of a DNM complication.

LEVEL OF EVIDENCE

4 Laryngoscope, 130:E567-E572, 2020.

Population-level mathematical modeling of antimicrobial resistance: a systematic review

BACKGROUND

Mathematical transmission models are increasingly used to guide public health interventions for infectious diseases, particularly in the context of emerging pathogens; however, the contribution of modeling to the growing issue of antimicrobial resistance (AMR) remains unclear. Here, we systematically evaluate publications on population-level transmission models of AMR over a recent period (2006-2016) to gauge the state of research and identify gaps warranting further work.

METHODS

We performed a systematic literature search of relevant databases to identify transmission studies of AMR in viral, bacterial, and parasitic disease systems. We analyzed the temporal, geographic, and subject matter trends, described the predominant medical and behavioral interventions studied, and identified central findings relating to key pathogens.

RESULTS

We identified 273 modeling studies; the majority of which (> 70%) focused on 5 infectious diseases (human immunodeficiency virus (HIV), influenza virus, Plasmodium falciparum (malaria), Mycobacterium tuberculosis (TB), and methicillin-resistant Staphylococcus aureus (MRSA)). AMR studies of influenza and nosocomial pathogens were mainly set in industrialized nations, while HIV, TB, and malaria studies were heavily skewed towards developing countries. The majority of articles focused on AMR exclusively in humans (89%), either in community (58%) or healthcare (27%) settings. Model systems were largely compartmental (76%) and deterministic (66%). Only 43% of models were calibrated against epidemiological data, and few were validated against out-of-sample datasets (14%). The interventions considered were primarily the impact of different drug regimens, hygiene and infection control measures, screening, and diagnostics, while few studies addressed de novo resistance, vaccination strategies, economic, or behavioral changes to reduce antibiotic use in humans and animals.

CONCLUSIONS

The AMR modeling literature concentrates on disease systems where resistance has been long-established, while few studies pro-actively address recent rise in resistance in new pathogens or explore upstream strategies to reduce overall antibiotic consumption. Notable gaps include research on emerging resistance in Enterobacteriaceae and Neisseria gonorrhoeae; AMR transmission at the animal-human interface, particularly in agricultural and veterinary settings; transmission between hospitals and the community; the role of environmental factors in AMR transmission; and the potential of vaccines to combat AMR.

Comparative characteristic of antimicrobial resistance in geriatric hospital: a retrospective cohort study

BACKGROUND AND AIMS

To examine antimicrobial resistance of commonly isolated pathogens in elderly hospitalized patients.

METHODS

Data regarding all clinically significant isolates from blood and urine cultures of patients admitted to a multilevel geriatric hospital during March 2015 to April 2016 were collected. Antimicrobial susceptibility testing was performed according to Clinical and Laboratory Standard Institute guidelines.

RESULTS

Escherichia coli, Proteus mirabilis, and Klebsiella pneumoniae were the most common isolates, with proportions of extended spectrum beta-lactamase positivity of 60, 40, and 61% respectively. Adjusted logistic regression models indicated that resistance of Escherichia coli to ceftriaxone [odds ratio (OR) 2.8, 95% confidence interval (CI) 1.5-5.1], ceftazidime (OR 2.8, 95% CI 1.5-5.1), ciprofloxacin (OR 2.2, 95% CI 1.2-4.0), amoxicillin/clavulanic acid (OR 2.3, 95% CI 1.2-4.3), and trimethoprim/sulfamethoxazole (OR 2.4, 95% CI 1.4-4.3) was significantly higher in skilled nursing wards than in acute geriatric wards. Resistance of Proteus mirabilis to ceftriaxone (OR 3.1, 95% CI 1.5-6.4) and Klebsiella pneumoniae to ciprofloxacin (OR 3.2, 95% CI 1.3-7.9) was significantly higher in skilled nursing wards than in acute wards.

CONCLUSIONS AND DISCUSSION

Antimicrobial resistance was found to be high in a multilevel geriatric hospital, especially in skilled nursing wards. These findings call for rethinking of the empirical antimicrobial therapy and of the efforts for prevention of nosocomial infection.

Comparing appropriateness of antibiotics for nursing home residents by setting of prescription initiation: a cross-sectional analysis

Background

The pervasive, often inappropriate, use of antibiotics in healthcare settings has been identified as a major public health threat due to the resultant widespread emergence of antibiotic resistant bacteria. In nursing homes (NH), as many as two-thirds of residents receive antibiotics each year and up to 75% of these are estimated to be inappropriate. The objective of this study was to characterize antibiotic therapy for NH residents and compare appropriateness based on setting of prescription initiation.

Methods

This was a retrospective, cross-sectional multi-center study that occurred in five NHs in southern Wisconsin between January 2013 and September 2014. All NH residents with an antibiotic prescribing events for suspected lower respiratory tract infections (LRTI), skin and soft tissue infections (SSTI), and urinary tract infections (UTI), initiated in-facility, from an emergency department (ED), or an outpatient clinic were included in this sample. We assessed appropriateness of antibiotic prescribing using the Loeb criteria based on documentation available in the NH medical record or transfer documents. We compared appropriateness by setting and infection type using the Chi-square test and estimated associations of demographic and clinical variables with inappropriate antibiotic prescribing using logistic regression.

Results

Among 735 antibiotic starts, 640 (87.1%) were initiated in the NH as opposed to 61 (8.3%) in the outpatient clinic and 34 (4.6%) in the ED. Inappropriate antibiotic prescribing for urinary tract infections differed significantly by setting: NHs (55.9%), ED (73.3%), and outpatient clinic (80.8%), P = .023. Regardless of infection type, patients who had an antibiotic initiated in an outpatient clinic had 2.98 (95% CI: 1.64–5.44, P < .001) times increased odds of inappropriate use.

Conclusions

Antibiotics initiated out-of-facility for NH residents constitute a small but not trivial percent of all prescriptions and inappropriate use was high in these settings. Further research is needed to characterize antibiotic prescribing patterns for patients managed in these settings as this likely represents an important, yet under recognized, area of consideration in attempts to improve antibiotic stewardship in NHs.

Infection Trends in US Nursing Homes, 2006-2013

OBJECTIVES

The objectives of this study were to estimate trends in the prevalence of infections in nursing home (NH) residents using 2006-2013 Minimum Data Set (MDS) data, estimate the number of all infections in 2013, and evaluate differences in trends between MDS versions 2.0 and 3.0.

DESIGN

Retrospective study.

SETTING

NHs in the United States.

PARTICIPANTS

All NH residents with a quarterly or annual MDS assessment in 2006-2013 (n = 30,366,807 assessments).

MEASUREMENTS

MDS 2.0 and 3.0 quarterly and annual assessment data (2006-2013) from over 15,000 NHs were used to estimate the 7-day prevalence of multidrug-resistant organism (MDRO) infection, pneumonia, septicemia, viral hepatitis, and wound infection and 30-day prevalence of urinary tract infection (UTI). Admission assessments were excluded. Annual infection counts were estimated using 2013 data. Changes in the prevalence of reported infections over time and differences in trends between MDS 2.0 and 3.0 were examined using tests of linear trends.

RESULTS

In 2013, there were an estimated 1.13 to 2.68 million infections in NH residents. UTI and pneumonia were the most commonly reported infections in every quarter, ranging from 5.6% to 8.1% and 1.4% to 2.5%, respectively. Prevalence of all infections increased in 2006-2010 (P values < .01). In 2011-2013, prevalence of UTI, MDRO, and wound infections decreased and viral hepatitis increased (P values < .0001). Between MDS 2.0 and 3.0, the prevalence of UTI, MDRO, and wound infections decreased and the prevalence of viral hepatitis increased (P values < .0001).

CONCLUSION

Infections are a major and persistent problem in NHs. Although MDS data are useful for identifying trends in infection prevalence, revisions in definitions need to be accounted for when evaluating trends over time. Additional research is needed to identify factors that contribute to changes in infection prevalence.