Comparative antimicrobial resistance and genomic diversity of Escherichia coli isolated from urinary tract infections in the community and in hospitals

Increased Severity of Escherichia Coli Peritonitis in Peritoneal Dialysis Patients Independent of Changes in in Vitro Antimicrobial Susceptibility Testing

Objective

Despite improvements in peritoneal dialysis (PD) technique, peritonitis continues to be one of the most frequent complications of PD. Nonresolving peritonitis remains a risk for severe anatomical peritoneal changes that may limit the viability of the membrane for dialysis purposes. We have observed remarkably poor outcome of peritonitis caused by Escherichia coli in the past 6 years. With its very low response rate to broad-spectrum antibiotics, the increased severity of E. coli peritonitis deteriorates peritoneal function and affects patient outcome.

Design

Retrospective study.

Setting

Two large PD units in two university hospitals.

Patients and Methods

The total number of patients reviewed was 456. The records of 49 E. coli peritonitis episodes were studied. The observation period started in 1980 and ended in March 2001. Sixteen males and 19 females were included. Severity was defined in terms of days of peritoneal inflammation, lack of response to a potentially useful antibiotic, requirement for catheter removal, and/or laparotomy. Study cases (study group) were those episodes appearing after 1996 (when the first severe cases appeared) and historic controls were episodes occurring before1996.

Results

In the study group, 18 peritonitis episodes developed in 15 patients. In the control group, 31 peritonitis episodes developed in 20 patients. There were no significant differences in clinical presentation; however, the outcome was significantly poorer for the later period. A severe outcome occurred in 50% of study versus 10% of control patients. In fact, 68% of the episodes registered before 1996 were cured in 3 days or less. Concurring with this trend, the numbers of surgical interventions and catheter removals were also higher in the study group. Strikingly, E. coli did not show changes in in vitro susceptibility testing to antibiotics, although the in vivo response was much worse.

Conclusions

We describe a change in the virulence of E. coli peritonitis episodes over the past 5 years leading to a high percentage of treatment failure, which does not depend on antibiotic sensitivity and seems to be dependent on changes in host response mechanisms.

Five-Year Antimicrobial Resistance Patterns of Urinary Escherichia coli at an Australian Tertiary Hospital: Time Series Analyses of Prevalence Data

This study describes the antimicrobial resistance temporal trends and seasonal variation of Escherichia coli (E. coli) urinary tract infections (UTIs) over five years, from 2009 to 2013, and compares prevalence of resistance in hospital- and community-acquired E. coli UTI. A cross sectional study of E. coli UTIs from patients attending a tertiary referral hospital in Canberra, Australia was undertaken. Time series analysis was performed to illustrate resistance trends. Only the first positive E. coli UTI per patient per year was included in the analysis. A total of 15,022 positive cultures from 8724 patients were identified. Results are based on 5333 first E. coli UTIs, from 4732 patients, of which 84.2% were community-acquired. Five-year hospital and community resistance rates were highest for ampicillin (41.9%) and trimethoprim (20.7%). Resistance was lowest for meropenem (0.0%), nitrofurantoin (2.7%), piperacillin-tazobactam (2.9%) and ciprofloxacin (6.5%). Resistance to amoxycillin-clavulanate, cefazolin, gentamicin and piperacillin-tazobactam were significantly higher in hospital- compared to community-acquired UTIs (9.3% versus 6.2%; 15.4% versus 9.7%; 5.2% versus 3.7% and 5.2% versus 2.5%, respectively). Trend analysis showed significant increases in resistance over five years for amoxycillin-clavulanate, trimethoprim, ciprofloxacin, nitrofurantoin, trimethoprim-sulphamethoxazole, cefazolin, ceftriaxone and gentamicin (P<0.05, for all) with seasonal pattern observed for trimethoprim resistance (augmented Dickey-Fuller statistic = 4.136; P = 0.006). An association between ciprofloxacin resistance, cefazolin resistance and ceftriaxone resistance with older age was noted. Given the relatively high resistance rates for ampicillin and trimethoprim, these antimicrobials should be reconsidered for empirical treatment of UTIs in this patient population. Our findings have important implications for UTI treatment based on setting of acquisition.

Defining relatedness in studies of transmission of antimicrobial-resistant organisms: variability in definitions across studies and impact of different approaches on study conclusions

OBJECTIVE

Comparison of studies evaluating patient-to-patient transmission of organisms is difficult, given the lack of standardized criteria. We used fluoroquinolone-resistant Escherichia coli (FQREC) as a model to characterize variability in definitions of relatedness across studies and to evaluate the resultant impact on study conclusions.

DESIGN

Narrative review and cohort study.

METHODS

The narrative review compared relatedness criteria across studies of FQREC. Additionally, an existing database was used to compare relatedness of isolates on the basis of molecular criteria alone versus molecular plus clinical criteria with different temporal cutoffs (hospitalization overlap of ≥1 day or allowance for nonoverlap of hospitalization dates of ≤7 days or ≤30 days).

RESULTS

Forty-six articles met narrative review inclusion criteria. Sixteen studies exclusively utilized molecular criteria to define relatedness. Thirty studies included molecular and clinical criteria. Of these, 6 included temporal data (ie, time period of isolate identification), 10 included patient location, and 14 included proximity and temporal criteria. For the database analysis, 353 patients were colonized with FQREC. There were 2 main clusters containing 48 and 17 related isolates within 49 pulsed-field gel electrophoresis types. Among the clusters, 18.4% of isolates were related by molecular criteria. Incorporating clinical criteria, fewer isolates were considered related: 5.7% of isolates using 30-day criteria, 3.1% using 7-day criteria, and 1.4% using 1-day overlap.

CONCLUSIONS

There is considerable variability in definitions of relatedness of FQREC. Utilizing molecular criteria alone to define relatedness overestimates transmission compared with definitions including clinical criteria. Standard definitions of relatedness in studies of antimicrobial-resistant organisms are needed.

Previous antimicrobial exposure is associated with drug-resistant urinary tract infections in children

OBJECTIVE

The aim of this study was to evaluate the impact of previous antimicrobial exposure on the development of antimicrobial resistance in children with their first urinary tract infection (UTI).

METHODS

We conducted a retrospective cohort study of children aged 6 months to 6 years and received their first diagnosis of UTI in a network of 27 outpatient pediatric practices between July 1, 2001, and May 31, 2006. We examined the relationship between antimicrobial resistance in UTI isolates and exposure to specific antimicrobial agents (amoxicillin, amoxicillin-clavulanate, cefdinir, trimethoprim-sulfamethoxazole, and azithromycin) in the previous 120 days. We developed multivariable logistic regression models for resistance to ampicillin, amoxicillin-clavulanate, trimethoprim-sulfamethoxazole, and first-generation and third-generation cephalosporins, adjusting for potential confounders such as age, number of siblings, recent hospitalizations, and child care exposure.

RESULTS

Of the 533 children who had a first UTI, 8%, 14%, and 21% were exposed to antimicrobial agents within 30, 60, and 120 days before the UTI, respectively. Amoxicillin exposure within 30 days (odds ratio [OR]: 3.6 [95% confidence interval (CI): 1.6-8.2]) and 31 to 60 days (OR: 2.8 [95% CI: 1.0-7.5]) before UTI both were associated with ampicillin resistance. Exposure to amoxicillin >60 days before the UTI was not associated with ampicillin resistance. Amoxicillin exposure within 30 days of UTI was also associated with amoxicillin-clavulanate resistance (OR: 3.9 [95% CI: 1.8-8.7]). No association between exposure to other antimicrobial agents and resistance to any of the antimicrobial agents was seen.

CONCLUSIONS

Recent antimicrobial exposure is associated with antimicrobial-resistant UTIs among pediatric outpatients, and the magnitude of this association decreases with time since exposure. Judicious antimicrobial prescribers should consider this association when selecting empiric antimicrobial agents for a new UTI and should use strategies to reduce unnecessary antimicrobial use to avoid development of resistant bacteria.

Antimicrobial drug use and resistance in Europe

Routine surveillance data indicate a relation between use and resistance and support interventions designed to reduce antimicrobial consumption at a national level in Europe.

Our study confronts the use of antimicrobial agents in ambulatory care with the resistance trends of 2 major pathogens, Streptococcus pneumoniae and Escherichia coli, in 21 European countries in 2000–2005 and explores whether the notion that antimicrobial drug use determines resistance can be supported by surveillance data at national aggregation levels. The data obtained from the European Surveillance of Antimicrobial Consumption and the European Antimicrobial Resistance Surveillance System suggest that variation of consumption coincides with the occurrence of resistance at the country level. Linear regression analysis showed that the association between antimicrobial drug use and resistance was specific and robust for 2 of 3 compound pathogen combinations, stable over time, but not sensitive enough to explain all of the observed variations. Ecologic studies based on routine surveillance data indicate a relation between use and resistance and support interventions designed to reduce antimicrobial drug consumption at a national level in Europe.

Antimicrobial resistance of Escherichia coli strains causing community-acquired urinary tract infections among insured and uninsured populations in a large urban center

We assessed the susceptibility of Escherichia coli strains causing communityacquired urinary tract infection (UTI) in a large urban center in Brazil, comparing two different populations (patients with health insurance vs. uninsured). 581 nonduplicate strains of E. coli were isolated. The prevalence of antimicrobial resistance was greater than 20% for ampicillin (51%), trimethoprim-sulfamethoxazole (43%), tetracycline (41%) and chloramphenicol (22%). Overall, 12% of the E. coli isolates were resistant to ciprofloxacin. Resistance prevalences to most antimicrobials were similar in the two study populations. Our data provide much needed information on the prevalence of antimicrobial resistance among E. coli causing communityacquired UTI in Brazil. Antimicrobial resistance among strains of E. coli causing community-acquired UTIs was relatively high, particularly resistance to ciprofloxacin.

[Microbial description of bacteriuria in long-term care facilities: a prospective study in the French Teaching Hospital of Strasbourg]

OBJECTIVE

The authors had for aim to assess, the incidence of symptomatic bacteriuria and the level of antibiotic resistance in bacteria identified in long-term care facilities (LTC).

DESIGN

Symptomatic bacteriuria cases were prospectively collected, during 9 months in the two LTC of the Strasbourg French Teaching Hospital (196 beds).

RESULTS

One hundred and eleven bacteriuria cases were included. They concerned 67 of the 274 residents (cumulative incidence: 2.07/1,000 patients-day). A gram-negative bacillus was identified in 85% of the symptomatic bacteriuria cases, and Escherichia coli in 40%. Sixty percent of the identified bacterial strain was resistant to amoxicillin (Amx-R) and 42% to the clavulanic acid combination (AmC-R). Third generation cephalosporins (3GC) were effective in 90% of Urinary tract infections (UTIs) and fluoroquinolones in 65% (Fq). Four bacterias with broad beta-lactamase spectrum were identified (0.04%) including 3 Enterobacter aerogenes. No yeast infection was diagnosed. E. coli strains were 65% Amx-R and 50% AmC-R. Concerning the Fq-R strains (15%), 50% were cotrimoxazole resistant (Stx-R) and 70% Amx-R; 3GC remained effective (82%).

CONCLUSION

In LTC, multi-drug resistance bacteria are rare and 3GCs seem to be the best first line treatment. Nevertheless, Fq-R is increasing (15 vs 8%), and attention must be paid to the antibiotic therapy used.

Susceptibility of Escherichia coli to the amoxycillin-clavulanate combination: which recommendations should be used to provide relevant information to clinicians?

This study compared MIC distributions of amoxycillin-clavulanate obtained with NCCLS and French (Comite de l'Antibiogramme de la Societe Francaise de Microbiologie; CA-SFM) methodologies for Escherichia coli isolates from urine that were non-susceptible to amoxycillin-clavulanate by the disk diffusion method. With the NCCLS and CA-SFM methods, 74% and 13%, respectively, of these isolates were susceptible to amoxycillin-clavulanate. Therefore, the apparent relatively poor efficacy of amoxycillin-clavulanate against E. coli in French hospitals probably reflects a methodological difference rather than a localised resistance problem. This implies that amoxycillin-clavulanate could be used as an alternative to fluoroquinolones for treatment of E. coli urinary tract infections. Susceptibility tests for amoxycillin-clavulanate should be standardised worldwide.

Escherichia coli : résistance aux quinolones et aux β-lactamines des souches cliniques isolées en Franche-Comté

AIM OF THE STUDY

Numerous European studies have reported an increase of resistance to quinolones among E. coli. We conducted a regional study to update our knowledge on this evolution.

MATERIALS AND METHODS

We evaluated the resistance phenotype and genotype of 115 clinical strains of E. coli. We collected data on individual treatment with fluoroquinolones, and the evolution of the use of these antimicrobial agents.

RESULTS

Resistance to nalidixic acid and ciprofloxacin was 13.0 and 6.9, respectively. The frequency of resistance increased from 1999 to 2001, from 7.5% to 13.0% for nalidixic acid and from 5.4% to 6.9% for fluoroquinolones. Resistance to quinolones was significantly associated to beta-lactams resistance and was slightly higher for nosocomial isolates compared to community-acquired isolates. Previous treatment with fluoroquinolones was the major risk factor associated to E. coli resistance. From 1997 to 2001, fluoroquinolones use has increased in our hospital and particularly in the community. Analysis of molecular epidemiology shows a large clonal diversity among E. coli isolates.

CONCLUSION

This study confirms the evolution through resistance to quinolones of E. coli isolates. This observation is not due to dissemination of resistant clonal strains and the selective pressure exerted by fluoroquinolones influences this evolution. Therapeutic alternatives, surveillance, and restriction of fluoroquinolones use are needed to control this spread of resistance.

Impact of Changing Patterns of Antimicrobial Resistance in Uropathogens: Emerging Treatment and Strategies

Urinary tract infection (UTI) is common, especially in women, and the microbiology of UTI is predictable. Over the past decade, numerous reports have documented increasing resistance among uropathogens to first-line agents for the treatment of UTI, especially trimethoprim/sulfamethoxazole (TMP/SMX). It is recommended that TMP/SMX should not be administered as empiric therapy for UTI in communities where resistance rates exceed 20%. However, reliable data regarding the true prevalence of resistance in a community are often lacking. Preliminary work has suggested that recent antimicrobial use is an important risk factor for infection with a TMP/SMX-resistant isolate. A better understanding of the epidemiology of resistance is needed to aid therapeutic decisions and devise interventions to reduce or slow emerging resistance.

Comparison of PCR-based methods for typing Escherichia coli

OBJECTIVE

To establish a library typing system appropriate for studying cross-transmission of Escherichia coli.

METHODS

Eighteen epidemiologically unrelated isolates were genotyped by means of pulsed-field gel electrophoresis (PFGE), random amplified polymorphic DNA (RAPD), repetitive (rep) PCR, and fluorescent amplified fragment length polymorphism (AFLP). Fingerprints were analyzed either by Pearson correlation or, in the case of AFLP, by Dice coefficients employing the novel 'uncertain band' software tool from GelCompar II. During a nine-month period, 112 isolates taken from 93 patients hospitalized in five intensive care units were analyzed by use of the two most discriminative PCR typing methods.

RESULTS

Genotyping by RAPD and rep-PCR revealed insufficient discrimination. Among 18 epidemiologically unrelated strains with 17 different PFGE patterns, IS3 rep-PCR and AFLP distinguished 10 and 18 types, respectively. Comparison of the different methods for analysis of AFLP fingerprints showed that the Dice coefficients, which ignore 'uncertain bands', offered the best concordance with visual interpretation. Consecutive isolates originating from the same patient differed in less than three fragments.

CONCLUSIONS

AFLP analysis showed the highest discriminative capacity for PCR typing of E. coli isolates. Analysis of fingerprints employing the Dice coefficients proved the most efficient method for an automated software-based retrieval of visually indistinguishable genotypes in an AFLP fingerprint database.

Epidemiological analysis of the spread of pathogens from a urological ward using genotypic, phenotypic and clinical parameters

Surveillance studies using molecular typing methods help clinicians assess the rate of potential spread of pathogens. The rate of cross transmission of uropathogens among patients on a urological ward was investigated. Urine samples were collected from 144 patients with urinary catheters and a significant bacteriuria. In a subgroup of 54 of these patients, cultures from a rectal swab were also made. Typing by PFGE, RAPD or bacteriocins showed that 41% of uropathogens were related and represented by 38 typing patterns. Endogenous infection was present in 30% and exogenous infection in 38% of isolates. Altogether, there was a high rate of clonal relationship amongst uropathogens in our urological ward and we conclude that hygienic means and measures are far from being optimal.

Prevalence and predictors of trimethoprim-sulfamethoxazole resistance among uropathogenic Escherichia coli isolates in Michigan

Resistance among uropathogenic Escherichia coli to trimethoprim-sulfamethoxazole (TMP-SMX) has increased. Risk factors for resistance and the impact on clinical failure have been poorly described. We performed a retrospective cohort study of women with acute uncomplicated cystitis seen at a university health center and at primary care clinics in southeastern Michigan from 1992 to 1999. The prevalence of TMP-SMX resistance increased from 8.1% to 15.8% (P=.01). Women who had taken TMP-SMX recently were >16 times as likely as women who had not taken antibiotics recently to be infected with an isolate resistant to this agent; those who had taken any other antibiotic were more than twice as likely to be infected with a resistant isolate. Women infected with a TMP-SMX-resistant isolate who were treated with TMP-SMX were >17 times as likely to have treatment failure. Recent antibiotic use is a risk factor for infection with a TMP-SMX-resistant isolate; patients who are infected with a TMP-SMX-resistant isolate and who are treated with this agent are at a higher risk for clinical failure.

Empirical therapy for uncomplicated urinary tract infections in an era of increasing antimicrobial resistance: a decision and cost analysis

Infectious Diseases Society of America guidelines state that uncomplicated urinary tract infections (UTIs) should be treated empirically with trimethoprim-sulfamethoxazole (TMP-SMZ), unless the community resistance among uropathogens exceeds 10%-20%, in which case a fluoroquinolone (FQ) should be used. However, the data to support this threshold are limited. We performed a cost-minimization and sensitivity analysis to determine what level of TMP-SMZ resistance in a community should trigger FQ use. The mean cost of empirical treatment with TMP-SMZ was US$92 when the proportion of resistant Escherichia coli was 0%, $106 when it was 20%, and $120 when it was 40%. The mean cost of empirical FQ treatment was $107 at current levels of FQ resistance. When >22% of E. coli in a community are TMP-SMZ-resistant, empirical FQ therapy becomes less costly than TMP-SMZ therapy. Treatment guidelines for empirical treatment of UTIs may need modification, and the threshold trigger for empirical FQ use should be raised to >20% TMP-SMZ resistance.

Bacteremia due to quinolone-resistant Escherichia coli in a teaching hospital in South Korea

Quinolone-resistant Escherichia coli (QREC) strains are being isolated with increasing frequency. From 1993 to 1998, 40 cases of QREC bacteremia were observed in a teaching hospital; 25 episodes (63.5%) were community-acquired. The incidence of QREC bacteremia increased steadily, from 6.7% to 24.6% during 5 years, and correlated with the significantly increased use of fluoroquinolones (P = .003, r = 0.98). When the 40 QREC bacteremic patients were compared with 80 patients with bacteremia due to quinolone-susceptible E. coli, prior fluoroquinolone use was the only independent risk factor for QREC bacteremia (P = .001). A high APACHE II score was the only independent risk factor for death. The rate of multidrug resistance of QREC was much higher (60%) than that of quinolone-susceptible isolates (13.8%). Pulsed-field gel electrophoresis patterns of these isolates were diverse. Therefore, the isolates revealed little evidence of clonal spread and may have emerged in direct response to the selective pressure exerted by prior fluoroquinolone use.