Risk factors for fluoroquinolone resistance in Enterococcus urinary tract infections in hospitalized patients

Fluoroquinolone resistance in Escherichia coli isolates after exposure to non-fluoroquinolone antibiotics: a retrospective case-control study

OBJECTIVES

To investigate whether prior exposure to non-fluoroquinolone antibiotics increases the risk of fluoroquinolone resistance in Escherichia coli.

METHODS

This was a secondary analysis of data collected retrospectively in a case-control study linking microbiological test results (isolated bacteria and their susceptibility) of urine samples routinely collected from primary, secondary and tertiary care patients in Belgium with information on prior antibiotic use at the patient level up to 1 year previously.

RESULTS

In urine samples from 6125 patients, 7204 E. coli isolates were retrieved [1949 fluoroquinolone-resistant isolates (cases) and 5255 fluoroquinolone-susceptible isolates (controls)]. After adjusting for potential confounders (including fluoroquinolone use) and correcting for multiple testing there were lower odds of fluoroquinolone resistance in E. coli isolates after exposure to cefazolin (OR = 0.65; 95% CI = 0.52-0.81; P = 0.00014) and higher odds after exposure to trimethoprim/sulfamethoxazole (OR = 1.56; 95% CI = 1.23-1.97; P =0.00020) or nitrofurantoin (OR = 1.50; 95% CI = 1.23-1.84; P =0.000083). A sensitivity analysis excluding samples with antibiotic use during the 6 months prior to the sampling date confirmed the higher odds of fluoroquinolone resistance after exposure to trimethoprim/sulfamethoxazole and nitrofurantoin.

CONCLUSIONS

Assuming no residual confounding or other biases, this study suggests that exposure to non-fluoroquinolone antibiotics, i.e. trimethoprim/sulfamethoxazole and nitrofurantoin, might be causally related to fluoroquinolone resistance in E. coli isolates from urinary samples. Future prospective research is needed to confirm non-fluoroquinolone antibiotics as potential drivers of fluoroquinolone resistance.

Predictors of fluoroquinolone-resistant bacteria in the rectal vault of men undergoing prostate biopsy

IMPORTANCE

Fluoroquinolone (FQ)-resistant rectal vault flora is associated with infectious complications in men undergoing transrectal ultrasound-guided prostate needle biopsy (TRUS-PNB).

OBJECTIVE

To determine the patient factors that predict FQ-resistant rectal cultures in men who are undergoing transrectal ultrasound-guided prostate needle biopsy.

METHODS

An IRB approved retrospective review of 6183 consecutive men who had undergone a rectal swab culture in preparation for TRUS-PNB between January 2013 and December 2014 was performed. Multivariable logistic regression was used to determine the clinical and demographic factors associated with FQ-resistant Enterobacteriaceae in the rectal vault.

RESULTS

Of the 6179 rectal swabs analyzed, 4842 (78%) were FQ-sensitive, and 1337 (22%) were FQ-resistant. On univariable analysis, increasing age, prior TRUS-PNB, higher number of biopsy cores obtained, diabetes mellitus, antimicrobial use within the past 6 months and non-Caucasian race were predictors of FQ-resistance (all p < 0.05). Men with FQ-resistant cultures were more likely to have benign pathology on TRUS-PNB (p = 0.004). On multivariable analysis, increasing patient age (OR = 1.01/year [1.00-1.02]), use of antimicrobials in the last 6 months (OR = 2.85[2.18-3.72]), African American (OR = 1.99 [1.66-2.37]), Asian (OR = 3.39 [2.63-4.37]), and Hispanic (OR = 2.10 [1.72-2.55]) races were independently associated with FQ-resistant rectal cultures. The overall infectious rate was 1.1% (56/5214) and the sepsis rate was 0.46% (24/5214). The infection rate in the FQ-resistant group was 3.9% (43/1107) compared to FQ-sensitive group 0.3% (13/4107), p < 0.001.

CONCLUSION

In this cohort, increasing age, recent antimicrobial-use, and non-Caucasian race were independent predictors of FQ-resistance in the rectal vault. As FQ-resistance is associated with infectious complications from transrectal ultrasound-guided prostate needle biopsy, understanding risk factors may assist infection control efforts.

Risk factors associated with fluoroquinolone-resistant enterococcal urinary tract infections in a tertiary care university hospital in north India

Background & objectives:

Fluoroquinolone resistance in both Gram-positive and Gram-negative bacteria has increased with the widespread use of fluoroquinolones. Fluoroquinolone resistance in Gram-negative bacilli has been widely studied, though staphylococci and enterococci are also notably resistant. Enterococci being the second most common cause of healthcare-associated urinary tract infections (UTIs) fluoroquinolones are often the drug of choice. This study was undertaken to assess the risk factors associated with fluoroquinolone-resistant enterococcal UTI in a tertiary level health facility in north India.

Methods:

A total of 365 patients with UTI caused by enterococci were studied over a period of two years. Patients with ciprofloxacin-resistant and susceptible UTI were considered as cases and controls, respectively. Resistance profile of the isolates against common antibiotics was studied by minimum inhibitory concentration (MIC) determination. Mechanisms for fluoroquinolone resistance was studied by efflux pump inhibitor activity and multiplex PCR targeting the qnr genes.

Results:

A total of 204 (55.89%) cases and 161 (44.1%) controls were identified. The fluoroquinolone-resistant isolates were significantly resistant to ampicillin, high strength aminoglycosides and vancomycin. The majority (78%) of the resistant isolates showed efflux pump activity. Treatment in indoor locations, presence of urinary catheters and pregnancy along with recent exposure to antibiotics especially fluoroquinolones, third generation cephalosporins and piperacillin-tazobactam were identified as independent risk factors.

Interpretation & conclusions:

Our results showed that fluoroquinolone resistance in enterococcal UTI was largely associated with indoor usage of antibiotics and use of indwelling devices. Knowledge of risk factors is important to curb this emergence of resistance.

Ciprofloxacin Resistance in Enterococcus faecalis Strains Isolated From Male Patients With Complicated Urinary Tract Infection

PURPOSE

Urinary tract infection (UTI) is one of the most prevalent bacterial infections, and fluoroquinolone therapy is a well-known standard regimen for UTI. The prevalence and risk factor analysis of fluoroquinolone resistance in enterococcal UTIs are not well documented. The aim of this study was to evaluate the antimicrobial susceptibility and risk factors for ciprofloxacin resistance in Enterococcus faecalis strains isolated from patients with complicated UTI.

MATERIALS AND METHODS

We evaluated 81 E. faecalis strains isolated from 81 male patients at a single teaching hospital over 3 years. The Vitek 2 automatic system was used for antimicrobial susceptibility analysis.

RESULTS

Antimicrobial resistance rates were rare for ampicillin/sulbactam, imipenem, and vancomycin in E. faecalis. Forty-six percent of the E. faecalis strains were resistant to levofloxacin, 47% were resistant to ciprofloxacin, and 58% were resistant to norfloxacin. E. faecalis strains were highly resistant to erythromycin (92%) and ftetracycline (96%). The risk factor analysis revealed that age intervals, the underlying diseases, catheterization, and the number of admissions did not increase the risk of ciprofloxacin resistance, whereas patients with hospital-acquired infection (odds ratio [OR], 18.15; 95% confidence interval [CI], 3.46 to 95.13; p=0.001), patients who were treated in a urological department (OR, 6.15; 95% CI, 1.5 to 25.41; p=0.012), and patients who were transferred from health care centers (OR, 7.393; 95% CI, 1.32 to 41.22; p=0.023) had an increased risk of ciprofloxacin resistance compared with the matched controls.

CONCLUSIONS

Ciprofloxacin is no longer a recommended therapy for E. faecalis from complicated UTI in men with risk factors. We suggest that ampicillin/sulbactam can be recommended as alternatives for treating ciprofloxacin-resistant E. faecalis strains associated with UTI in Korea.

Global fluoroquinolone resistance epidemiology and implictions for clinical use

This paper on the fluoroquinolone resistance epidemiology stratifies the data according to the different prescription patterns by either primary or tertiary caregivers and by indication. Global surveillance studies demonstrate that fluoroquinolone resistance rates increased in the past years in almost all bacterial species except S. pneumoniae and H. influenzae, causing community-acquired respiratory tract infections. However, 10 to 30% of these isolates harbored first-step mutations conferring low level fluoroquinolone resistance. Fluoroquinolone resistance increased in Enterobacteriaceae causing community acquired or healthcare associated urinary tract infections and intraabdominal infections, exceeding 50% in some parts of the world, particularly in Asia. One to two-thirds of Enterobacteriaceae producing extended spectrum β-lactamases were fluoroquinolone resistant too. Furthermore, fluoroquinolones select for methicillin resistance in Staphylococci. Neisseria gonorrhoeae acquired fluoroquinolone resistance rapidly; actual resistance rates are highly variable and can be as high as almost 100%, particularly in Asia, whereas resistance rates in Europe and North America range from <10% in rural areas to >30% in established sexual networks. In general, the continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some guidelines, for example, treatment of urinary tract, intra-abdominal, skin and skin structure infections, and traveller's diarrhea, or even precludes the use in indications like sexually transmitted diseases and enteric fever.

Resistance surveillance studies: a multifaceted problem--the fluoroquinolone example

INTRODUCTION

This review summarizes data on the fluoroquinolone resistance epidemiology published in the previous 5 years.

MATERIALS AND METHODS

The data reviewed are stratified according to the different prescription patterns by either primary- or tertiary-care givers and by indication. Global surveillance studies demonstrate that fluoroquinolone- resistance rates increased in the past several years in almost all bacterial species except Staphylococcus pneumoniae and Haemophilus influenzae causing community-acquired respiratory tract infections (CARTIs), as well as Enterobacteriaceae causing community-acquired urinary tract infections. Geographically and quantitatively varying fluoroquinolone resistance rates were recorded among Gram-positive and Gram-negative pathogens causing healthcare-associated respiratory tract infections. One- to two-thirds of Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) were fluoroquinolone resistant too, thus, limiting the fluoroquinolone use in the treatment of community- as well as healthcare-acquired urinary tract and intra-abdominal infections. The remaining ESBL-producing or plasmid-mediated quinolone resistance mechanisms harboring Enterobacteriaceae were low-level quinolone resistant. Furthermore, 10-30 % of H. influenzae and S. pneumoniae causing CARTIs harbored first-step quinolone resistance determining region (QRDR) mutations. These mutants pass susceptibility testing unnoticed and are primed to acquire high-level fluoroquinolone resistance rapidly, thus, putting the patient at risk. The continued increase in fluoroquinolone resistance affects patient management and necessitates changes in some current guidelines for the treatment of intra-abdominal infections or even precludes the use of fluoroquinolones in certain indications like gonorrhea and pelvic inflammatory diseases in those geographic areas in which fluoroquinolone resistance rates and/or ESBL production is high. Fluoroquinolone resistance has been selected among the commensal flora colonizing the gut, nose, oropharynx, and skin, so that horizontal gene transfer between the commensal flora and the offending pathogen as well as inter- and intraspecies recombinations contribute to the emergence and spread of fluoroquinolone resistance among pathogenic streptococci. Although interspecies recombinations are not yet the major cause for the emergence of fluoroquinolone resistance, its existence indicates that a large reservoir of fluoroquinolone resistance exists. Thus, a scenario resembling that of a worldwide spread of β-lactam resistance in pneumococci is conceivable. However, many resistance surveillance studies suffer from inaccuracies like the sampling of a selected patient population, restricted geographical sampling, and undefined requirements of the user, so that the results are biased. The number of national centers is most often limited with one to two participating laboratories, so that such studies are point prevalence but not surveillance studies. Selected samples are analyzed predominantly as either hospitalized patients or patients at risk or those in whom therapy failed are sampled; however, fluoroquinolones are most frequently prescribed by the general practitioner. Selected sampling results in a significant over-estimation of fluoroquinolone resistance in outpatients. Furthermore, the requirements of the users are often not met; the prescribing physician, the microbiologist, the infection control specialist, public health and regulatory authorities, and the pharmaceutical industry have diverse interests, which, however, are not addressed by different designs of a surveillance study. Tools should be developed to provide customer-specific datasets.

CONCLUSION

Consequently, most surveillance studies suffer from well recognized but uncorrected biases or inaccuracies. Nevertheless, they provide important information that allows the identification of trends in pathogen incidence and antimicrobial resistance.

Mechanisms of and risk factors for fluoroquinolone resistance in clinical Enterococcus faecalis isolates from patients with urinary tract infections

We examined Enterococcus faecalis strains clinically isolated from 100 patients with urinary tract infections (UTIs) for their susceptibility to levofloxacin (LVX) by measuring the MIC and investigated amino acid mutations by direct DNA sequencing, which were then correlated with LVX resistance. Next, we studied risk factors for LVX resistance, such as age, gender, and previous fluoroquinolone use, and investigated the statistical correlation of these risk factors with each amino acid mutation and LVX resistance. Of the 100 isolates tested, 14 isolates showed LVX resistance and all of these isolates had amino acid mutations. We demonstrated that 2 out of 4 mutations (Ser83-to-Ile in gyrA and Ser80-to-Ile in parC) had a significant correlation with LVX resistance. There was a significant relationship between isolates with 2 or 3 amino acid mutations and LVX resistance. In addition, we found a significant correlation between the previous use of fluoroquinolones and LVX resistance or the presence of mutations and also demonstrated that previous use of other types of antibiotics was significantly related to the presence of mutations by multivariate analysis. In conclusion, we found significant correlation between amino acid mutations in E. faecalis, LVX resistance, and risk factors such as previous use of fluoroquinolones.