Association between urinary community-acquired fluoroquinolone-resistant Escherichia coli and neighbourhood antibiotic consumption: a population-based case-control study

BACKGROUND

It is unknown whether increased use of antibiotics in a community increases the risk of acquiring antibiotic resistance by individuals living in that community, regardless of prior individual antibiotic consumption and other risk factors for antibiotic resistance.

METHODS

We used a hierarchical multivariate logistic regression approach to evaluate the association between neighbourhood fluoroquinolone consumption and individual risk of colonisation or infection of the urinary tract with fluoroquinolone-resistant Escherichia coli. We did a population-based case-control study of adults (aged ≥22 years) living in 1733 predefined geographical statistical areas (neighbourhoods) in Israel. A multilevel study design was used to analyse data derived from electronic medical records of patients enrolled in the Clalit state-mandated health service.

FINDINGS

300 105 events with E coli growth and 1 899 168 cultures with no growth were identified from medical records and included in the analysis. 45 427 (16·8%) of 270 190 women and 8835 (29·5%) of 29 915 men had fluoroquinolone-resistant E coli events. We found an independent association between residence in a neighbourhood with higher antibiotic consumption and an increased risk of bacteriuria caused by fluoroquinolone-resistant E coli. Odds ratios (ORs) for the quintiles with higher neighbourhood consumption (compared with the lowest quintile) were 1·15 (95% CI 1·06-1·24), 1·31 (1·20-1·43), 1·41 (1·29-1·54), and 1·51 (1·38-1·65) for women, and 1·17 (1·02-1·35), 1·24 (1·06-1·45), 1·35 (1·15-1·59), and 1·50 (1·26-1·77) for men. Results remained significant when the analysis was restricted to patients who had not consumed fluoroquinolones themselves.

INTERPRETATION

These data suggest that increased use of antibiotics in specific geographical areas is associated with an increased personal risk of acquiring antibiotic-resistant bacteria, independent of personal history of antibiotic consumption and other known risk factors for antimicrobial resistance.

FUNDING

None.

Effect of outpatient antibiotics for urinary tract infections on antimicrobial resistance among commensal Enterobacteriaceae: a multinational prospective cohort study

OBJECTIVES

We quantified the impact of antibiotics prescribed in primary care for urinary tract infections (UTIs) on intestinal colonization by ciprofloxacin-resistant (CIP-RE) and extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-PE), while accounting for household clustering.

METHODS

Prospective cohort study from January 2011 to August 2013 at primary care sites in Belgium, Poland and Switzerland. We recruited outpatients requiring antibiotics for suspected UTIs or asymptomatic bacteriuria (exposed patients), outpatients not requiring antibiotics (non-exposed patients), and one to three household contacts for each patient. Faecal samples were tested for CIP-RE, ESBL-PE, nitrofurantoin-resistant Enterobacteriaceae (NIT-RE) and any Enterobacteriaceae at baseline (S1), end of antibiotics (S2) and 28 days after S2 (S3).

RESULTS

We included 300 households (205 exposed, 95 non-exposed) with 716 participants. Most exposed patients received nitrofurans (86; 42%) or fluoroquinolones (76; 37%). CIP-RE were identified in 16% (328/2033) of samples from 202 (28%) participants. Fluoroquinolone treatment caused transient suppression of Enterobacteriaceae (S2) and subsequent two-fold increase in CIP-RE prevalence at S3 (adjusted prevalence ratio (aPR) 2.0, 95% CI 1.2-3.4), with corresponding number-needed-to-harm of 12. Nitrofurans had no impact on CIP-RE (aPR 1.0, 95% CI 0.5-1.8) or NIT-RE. ESBL-PE were identified in 5% (107/2058) of samples from 71 (10%) participants, with colonization not associated with antibiotic exposure. Household exposure to CIP-RE or ESBL-PE was associated with increased individual risk of colonization: aPR 1.8 (95% CI 1.3-2.5) and 3.4 (95% CI 1.3-9.0), respectively.

CONCLUSIONS

These findings support avoidance of fluoroquinolones for first-line UTI therapy in primary care, and suggest potential for interventions that interrupt household circulation of resistant Enterobacteriaceae.

Scientific evidence and research in antimicrobial stewardship

Evaluating the impact of antibiotic stewardship programs is challenging. There is evidence that they are effective in terms of reducing the consumption and cost of antibiotics, although establishing their impact on antimicrobial resistance (beyond restrictive policies in outbreaks caused by specific antimicrobial resistant organisms) and clinical outcomes is more difficult. Proper definitions of exposure and outcome variables, the use of advanced and appropriate statistical analyses and well-designed quasi-experimental studies would more accurately support the conclusions. Cluster randomized trials should be used whenever possible and appropriate, although the limitations of this approach should also be acknowledged. These issues are reviewed in this paper. We conclude that there are good research opportunities in the field of antibiotic stewardship.

Multilevel competing risk models to evaluate the risk of nosocomial infection

Introduction

Risk factor analyses for nosocomial infections (NIs) are complex. First, due to competing events for NI, the association between risk factors of NI as measured using hazard rates may not coincide with the association using cumulative probability (risk). Second, patients from the same intensive care unit (ICU) who share the same environmental exposure are likely to be more similar with regard to risk factors predisposing to a NI than patients from different ICUs. We aimed to develop an analytical approach to account for both features and to use it to evaluate associations between patient- and ICU-level characteristics with both rates of NI and competing risks and with the cumulative probability of infection.

Methods

We considered a multicenter database of 159 intensive care units containing 109,216 admissions (813,739 admission-days) from the Spanish HELICS-ENVIN ICU network. We analyzed the data using two models: an etiologic model (rate based) and a predictive model (risk based). In both models, random effects (shared frailties) were introduced to assess heterogeneity. Death and discharge without NI are treated as competing events for NI.

Results

There was a large heterogeneity across ICUs in NI hazard rates, which remained after accounting for multilevel risk factors, meaning that there are remaining unobserved ICU-specific factors that influence NI occurrence. Heterogeneity across ICUs in terms of cumulative probability of NI was even more pronounced. Several risk factors had markedly different associations in the rate-based and risk-based models. For some, the associations differed in magnitude. For example, high Acute Physiology and Chronic Health Evaluation II (APACHE II) scores were associated with modest increases in the rate of nosocomial bacteremia, but large increases in the risk. Others differed in sign, for example respiratory vs cardiovascular diagnostic categories were associated with a reduced rate of nosocomial bacteremia, but an increased risk.

Conclusions

A combination of competing risks and multilevel models is required to understand direct and indirect risk factors for NI and distinguish patient-level from ICU-level factors.

Factors associated with late antiretroviral therapy initiation in Cameroon: a representative multilevel analysis

OBJECTIVES

Many people living with HIV/AIDS in resource-limited settings begin antiretroviral therapy (ART) at low CD4 counts. Here, we investigated the simultaneous effect of individual-, facility- and regional-level factors on late ART initiation.

METHODS

We conducted a survey in a nationally representative sample of 55 HIV treatment facilities in Cameroon. Medical records of 4935 patients >15 years of age who initiated ART in the month of October during the period 2007-10 were reviewed to gather individual characteristics. Late ART initiation was defined as CD4 count ≤ 100 cells/mm(3). Facility- and regional-level characteristics were also collected. Two-level regression logistic models were used to identify factors associated with late ART initiation.

RESULTS

Late ART initiation was associated with being a male younger than 45 years versus female younger than 45 years [adjusted OR (AOR) = 1.5, 95% CI: 1.3-1.7] and initiating ART in the period 2007-09 versus 2010 (AOR = 1.2, 95% CI: 1.0-1.4). Late initiation was more likely in central than in district hospitals (AOR = 1.3, 95% CI: 1.1-1.6) and in hospitals without a mother-to-child transmission programme (AOR = 1.9, 95% CI: 1.3-2.8). Living in a region with a higher comprehensive knowledge of HIV/AIDS was associated with not initiating ART late (AOR = 0.8, 95% CI: 0.6-1.0).

CONCLUSIONS

This study shows that risk factors associated with late ART initiation operate at multiple levels and that multilevel interventions are therefore necessary to promote earlier HIV testing and treatment.

Trimethoprim and ciprofloxacin resistance and prescribing in urinary tract infection associated with Escherichia coli: a multilevel model

OBJECTIVES

Individual and group level factors associated with the probability of antimicrobial resistance of uropathogenic Escherichia coli were analysed in a multilevel model.

METHODS

Adult patients consulting with a suspected urinary tract infection (UTI) in 22 general practices over a 9 month period supplied a urine sample for laboratory analysis. Cases were patients with a UTI associated with a resistant E. coli. Previous antimicrobial exposure and other patient characteristics were recorded from the medical files.

RESULTS

Six hundred and thirty-three patients with an E. coli UTI and a full record for all variables were included. Of the E. coli isolates, 36% were resistant to trimethoprim and 12% to ciprofloxacin. A multilevel logistic regression model was fitted. The odds that E. coli was resistant increased with increasing number of prescriptions over the previous year for trimethoprim from 1.4 (0.8-2.2) for one previous prescription to 4.7 (1.9-12.4) for two and 6.4 (2.0-25.4) for three or more. For ciprofloxacin the ORs were 2.7 (1.2-5.6) for one and 6.5 (2.9-14.8) for two or more. The probability that uropathogenic E. coli was resistant showed important variation between practices and a difference of 17% for trimethoprim and 33% for ciprofloxacin was observed for an imaginary patient moving from a practice with low to a practice with high probability. This difference could not be explained by practice prescribing or practice resistance levels.

CONCLUSIONS

Previous antimicrobial use and the practice visited affect the risk that a patient with a UTI will be diagnosed with an E. coli resistant to this agent, which was particularly important for ciprofloxacin.