Risk factors for fluoroquinolone resistance in Gram-negative bacilli causing healthcare-acquired urinary tract infections

Stimulating Transcription in Antibiotic-Tolerant Escherichia coli Sensitizes It to Fluoroquinolone and Nonfluoroquinolone Topoisomerase Inhibitors

Antibiotic tolerant bacteria and persistent cells that remain alive after a course of antibiotic treatment can foster the chronicity of infections and the development of antibiotic resistance. Elucidating how bacteria overcome antibiotic action and devising strategies to bolster a new drug's activity can allow us to preserve our antibiotic arsenal. Here, we investigate strategies to potentiate the activities of topoisomerase inhibitors against nongrowing Escherichia coli that are often recalcitrant to existing antibiotics. We focus on sensitizing bacteria to the fluoroquinolone (FQ) levofloxacin (Levo) and to the spiropyrimidinetrione zoliflodacin (Zoli)-the first antibiotic in its class of compounds in clinical development. We found that metabolic stimulation either alone or in combination with inhibiting the AcrAB-TolC efflux pump sensitized stationary-phase E. coli to Levo and Zoli. We demonstrate that the added metabolites increased proton motive force generation and ATP production in stationary-phase cultures without restarting growth. Instead, the stimulated bacteria increased transcription and translation, which rendered the populations more susceptible to topoisomerase inhibitors. Our findings illuminate potential vulnerabilities of antibiotic-tolerant bacteria that can be leveraged to sensitize them to new and existing classes of topoisomerase inhibitors. These approaches enable us to stay one step ahead of adaptive bacteria and safeguard the efficacy of our existing antibiotics.

Quinolone Consumption by Mothers Increases Their Children's Risk of Acquiring Quinolone-Resistant Bacteriuria

BACKGROUND

Quinolone resistance has been documented in the pediatric population, although their use is limited in children. This study investigated the effect of maternal quinolone use on gram-negative bacterial resistance to quinolones in their offspring.

METHODS

We conducted a population-based, unmatched case-control study during 2010-2017. Cases were all children aged 0.5-17 years with community acquired, gram-negative quinolone-resistant bacteriuria. Controls were similar children with quinolone-sensitive bacteriuria. Only the first positive urine cultures for each child were included. Data on quinolones dispensed to the mother, any antibiotics dispensed to the children, age, sex, ethnicity, and prior hospitalizations were collected. Children with previous quinolone use were excluded.

RESULTS

The study population consisted of 40 204 children. Quinolone resistance was detected in 2182 (5.3%) urine cultures. The median age was 5 years, with 93.7% females and 77.6% Jewish. A total of 26 937 (65%) of the children received any antibiotic and 1359 (3.2%) of the mothers received quinolones in the 6 months preceding bacteriuria. Independent risk factors were quinolone dispensed to the mothers (odds ratio [OR], 1.50 [95% confidence interval {CI}, 1.22-1.85]), Arab ethnicity (OR, 1.99 [95% CI, 1.81-2.19]), and antibiotic dispensed to the child (OR, 1.54 [95% CI, 1.38-1.71]). Compared with children aged 12-17 years, younger children had 1.33-1.43 increased odds for quinolone-resistant bacteriuria.

CONCLUSIONS

Quinolone prescription to mothers was linked to increased risk of community-acquired, quinolone-resistant bacteria in their offspring, by about 50%. This is another example of the deleterious ecological effects of antibiotic use and should be considered when prescribing antibiotics.

The Impact of Reported Beta-Lactam Allergy in Hospitalized Patients With Hematologic Malignancies Requiring Antibiotics

Background

Patients hospitalized with hematologic malignancy are particularly vulnerable to infection. The impact of reported beta-lactam (BL) allergy in this population remains unknown.

Methods

This was a retrospective cohort study of adult inpatients with hematologic malignancy admitted at 2 tertiary care hospitals from 2010 through 2015. The primary outcome was hospital length of stay (LOS) after administration of the first antibiotic. Secondary outcomes included readmission, mortality, complications, hospital charges, and antibiotic usage. Our goal was to define the impact of BL-only allergy (BLOA) label on clinical outcomes compared to those with no BL allergy (NBLA) in hematologic malignancy inpatients who required systemic antibiotics.

Results

In our cohort (n = 4671), 38.3% had leukemia, 4.9% had Hodgkin lymphoma, 36.1% had non-Hodgkin lymphoma, and 20.7% had multiple myeloma. Among patients, 35.1% reported antibiotic allergy, and 14.1% (n = 660) had BLOA (including 9.3% with penicillin-only allergy and 3.3% cephalosporin-only allergy). Patients with BLOA had longer median LOS compared to patients with NBLA (11.3 vs 7.6 days, P < .001), which remained significant after multivariable adjustment. Patients with BLOA also had significantly worse outcomes in terms of mortality rate at 30 days (7.6% vs 5.3%, P = .017) and 180 days (15.8% vs 12.2%, P = .013), 30-day readmission rate, Clostridium difficile rate, hospital charges ($223 046 vs $173 256, P < .001), antibiotic classes used, and antibiotic duration.

Conclusions

In hospitalized patients with hematologic malignancy, patients with reported BL allergy had worse clinical outcomes and higher healthcare cost than those without BL allergy label.

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.

Prevalence and Factors Associated With Multidrug-Resistant Gram-Negative Organisms in Patients With Spinal Cord Injury

OBJECTIVE

Infections caused by multidrug-resistant gram-negative organisms (MDRGNOs) have been increasing every year. The objective of this study was to describe the prevalence of MDRGNOs and factors associated with MDRGNOs in patients with spinal cord injury or disorder (SCI/D).

DESIGN

Retrospective cohort study.

METHODS

Department of Veterans Affairs (VA) electronic health record data from 142 VA facilities were evaluated for 19,642 patients with SCI/D. Multivariable cluster-adjusted models were fit to identify factors associated with MDRGNO.

RESULTS

Gram-negative (GN) cultures occurred in 44% of patients with SCI/D receiving care at VA facilities, and 11,527 (41.3%) GN cultures had an MDRGNO. The most frequent GN organisms (GNOs) were Escherichia coli (28.5%), Klebsiella pneumoniae (17.0%), and Pseudomonas aeruginosa (16.0%). Two-thirds of GN cultures were from the outpatient setting, where MDRGNO prevalence was 37.6%. Significant geographic variation in the prevalence of MDRGNOs was identified (South, 44.7%; Northeast, 44.3%; West, 36.8%; Midwest, 34.4%). Other factors associated with an MDRGNO were older age, injury characteristics, comorbidities, specimen type, healthcare setting, and healthcare exposure. Black (odds ratio [OR], 1.58; 95% confidence interval [CI], 1.39–1.78) and Hispanic race (OR, 1.58; 95% CI, 1.28–1.95), polymicrobial culture (OR, 2.67; 95% CI, 2.46–2.90), and antibiotic use in the previous 90 days (OR, 1.62; 95% CI, 1.50–1.76) were also associated with having an MDRGNO.

CONCLUSIONS

MDRGNOs were common in community and healthcare settings among veterans with SCI/D, with significant geographic variation. Health care and antibiotic exposures were significant factors associated with MDRGNOs. Priority should be given to controlling the spread of MDRGNOs in this special population, including a focus on judicious use of antibiotics.

Infect Control Hosp Epidemiol 2017;38:1464–1471

An update on the management of urinary tract infections in the era of antimicrobial resistance

Urinary tract infections (UTIs) caused by antibiotic-resistant Gram-negative bacteria are a growing concern due to limited therapeutic options. Gram-negative bacteria, specifically Enterobacteriaceae, are common causes of both community-acquired and hospital acquired UTIs. These organisms can acquire genes that encode for multiple antibiotic resistance mechanisms, including extended-spectrum-lactamases (ESBLs), AmpC- β -lactamase, and carbapenemases. The assessment of suspected UTI includes identification of characteristic symptoms or signs, urinalysis, dipstick or microscopic tests, and urine culture if indicated. UTIs are categorized according to location (upper versus lower urinary tract) and severity (uncomplicated versus complicated). Increasing rates of antibiotic resistance necessitate judicious use of antibiotics through the application of antimicrobial stewardship principles. Knowledge of the common causative pathogens of UTIs including local susceptibility patterns are essential in determining appropriate empiric therapy. The recommended first-line empiric therapies for acute uncomplicated bacterial cystitis in otherwise healthy adult nonpregnant females is a 5-day course of nitrofurantion or a 3-g single dose of fosfomycin tromethamine. Second-line options include fluoroquinolones and β-lactams, such as amoxicillin-clavulanate. Current treatment options for UTIs due to AmpC- β -lactamase-producing organisms include fosfomycin, nitrofurantion, fluoroquinolones, cefepime, piperacillin-tazobactam and carbapenems. In addition, treatment options for UTIs due to ESBLs-producing Enterobacteriaceae include nitrofurantion, fosfomycin, fluoroquinolones, cefoxitin, piperacillin-tazobactam, carbapenems, ceftazidime-avibactam, ceftolozane-tazobactam, and aminoglycosides. Based on identification and susceptibility results, alternatives to carbapenems may be used to treat mild-moderate UTIs caused by ESBL-producing Enterobacteriaceae. Ceftazidime-avibactam, colistin, polymixin B, fosfomycin, aztreonam, aminoglycosides, and tigecycline are treatment options for UTIs caused by carbapenem-resistant Enterobacteriaceae (CRE). Treatment options for UTIs caused by multidrug resistant (MDR)-Pseudomonas spp. include fluoroquinolones, ceftazidime, cefepime, piperacillin-tazobactam, carbapenems, aminoglycosides, colistin, ceftazidime-avibactam, and ceftolozane-tazobactam. The use of fluoroquinolones for empiric treatment of UTIs should be restricted due to increased rates of resistance. Aminoglycosides, colistin, and tigecycline are considered alternatives in the setting of MDR Gram-negative infections in patients with limited therapeutic options.

Risk factors for resistance to ciprofloxacin in community-acquired urinary tract infections due to Escherichia coli in an elderly population

BACKGROUND

Antimicrobial resistance to ciprofloxacin is rising worldwide, especially in bacteria causing urinary tract infections (UTIs). Prudent use of current antibiotic drugs is therefore necessary.

OBJECTIVES

We analysed (modifiable) risk factors for ciprofloxacin-resistant Escherichia coli.

METHODS

Urinary cultures of UTIs caused by E. coli were collected from participants in the Rotterdam Study, a prospective cohort study in an elderly population, and analysed for susceptibility to ciprofloxacin. Multivariate logistic regression was performed to investigate several possible risk factors for resistance.

RESULTS

Ciprofloxacin resistance in 1080 E. coli isolates was 10.2%. Multivariate analysis showed that higher age (OR 1.03; 95% CI 1.00-1.05) and use of two (OR 5.89; 95% CI 3.45-10.03) and three or more (OR 3.38; 95% CI 1.92-5.97) prescriptions of fluoroquinolones were associated with ciprofloxacin resistance, while no association between fluoroquinolone use more than 1 year before culture and ciprofloxacin resistance could be demonstrated. Furthermore, a high intake of pork (OR 3.68; 95% CI 1.36-9.99) and chicken (OR 2.72; 95% CI 1.08-6.85) and concomitant prescription of calcium supplements (OR 2.51; 95% CI 1.20-5.22) and proton pump inhibitors (OR 2.04; 95% CI 1.18-3.51) were associated with ciprofloxacin resistance.

CONCLUSIONS

Ciprofloxacin resistance in community-acquired UTI was associated with a high intake of pork and chicken and with concomitant prescription of calcium supplements and proton pump inhibitors. Modification of antibiotic use in animals as well as temporarily stopping the prescription of concomitant calcium and proton pump inhibitors need further evaluation as strategies to prevent ciprofloxacin resistance.

Susceptibility pattern of uropathogens to ciprofloxacin at the Ghana police hospital

INTRODUCTION

Reports of increasing resistance of uropathogens to antimicrobials is of global concern. Culture and drug susceptibility tests remain a vital guide to effective therapy. The aim of this study was to determine the susceptibility pattern of isolated uropathogens to ciprofloxacin at the Ghana Police Hospital.

METHODS

A total of 705 mid-stream urine samples were collected from patients suspected of having urinary tract infection, and visited the Ghana Police Hospital's laboratory from December 2013 to March 2014. Samples were cultured and isolates identified by standard methods, after which isolates susceptibility to ciprofloxacin was determined.

RESULTS

Prevalence of urinary tract infection among patients' whose samples were analyzed was 15.9%. Predominant uropathogens isolated were E. coli (46.4%), Coliform (41.1%) and Coliform spp. with Candida (6.2%). Other isolates were Pseudomonas spp. (2.7%), Salmonella spp. (1.8%), Candida spp. (0.9%) and Klebsiella spp (0.9%). The overall resistance among the top three isolated uropathogens to ciprofloxacin was 35.9%. Resistance pattern demonstrated by respective isolates to ciprofloxacin were: E. coli (38.5%), Coliform (54.3%), and Coliform spp. with Candida (15%). The other isolates showed 100% sensitivity.

CONCLUSION

This study revealed a relatively high ciprofloxacin resistance among isolated uropathogens, hence, the need for prudent prescribing and use of ciprofloxacin in urinary tract infection management.

Risk factors for ambulatory urinary tract infections caused by high-MIC fluoroquinolone-susceptible Escherichia coli in women: results from a large case-control study

OBJECTIVES

The prevalence of high-MIC fluoroquinolone-susceptible Escherichia coli (FQSEC) has been increasing. These isolates are one step closer to full fluoroquinolone (FQ) resistance and may lead to delayed response to FQ therapy. Our study aimed to investigate the epidemiology of high-MIC FQSEC in ambulatory urinary tract infections (UTIs).

PATIENTS AND METHODS

A case-control study was conducted at outpatient services within the University of Pennsylvania Health System, Philadelphia. All female subjects with non-recurrent UTI caused by FQSEC (levofloxacin MIC < 4 mg/L) were enrolled. Cases were subjects with high-MIC FQSEC UTI (levofloxacin MIC >0.12 but < 4 mg/L) and controls were subjects with low-MIC FQSEC UTI (levofloxacin MIC ≤0.12 mg/L). Data on microbiology results and baseline characteristics were extracted from electronic medical records.

RESULTS

During the 3 year study period (May 2008-April 2011), 11 287 episodes of E. coli bacteriuria were identified. The prevalence of FQSEC, FQ-intermediate susceptible E. coli and FQ-resistant E. coli was 75.0%, 0.4% and 24.6%, respectively. A total of 2001 female subjects with FQSEC UTI were enrolled into our study (165 cases and 1836 controls). Independent risk factors for high-MIC FQ susceptibility included Asian race (OR = 2.92; 95% CI = 1.29-6.58; P = 0.02), underlying renal disease (OR = 2.18; 95% CI = 1.15-4.14; P = 0.02) and previous nitrofurantoin exposure (OR = 8.86; 95% CI = 1.95-40.29; P = 0.005).

CONCLUSIONS

Asian race, underlying renal disease and previous exposure to nitrofurantoin were identified as independent risk factors for high-MIC FQSEC. There may be some factors that are more common in Asians, which may result in the selection of high-MIC FQSEC. Further studies are necessary to explore these findings.

Epidemiological interpretation of studies examining the effect of antibiotic usage on resistance

Bacterial resistance to antibiotics is a growing clinical problem and public health threat. Antibiotic use is a known risk factor for the emergence of antibiotic resistance, but demonstrating the causal link between antibiotic use and resistance is challenging. This review describes different study designs for assessing the association between antibiotic use and resistance and discusses strengths and limitations of each. Approaches to measuring antibiotic use and antibiotic resistance are presented. Important methodological issues such as confounding, establishing temporality, and control group selection are examined.

Prevalence and risk factor analysis of resistant Escherichia coli urinary tract infections in the emergency department

BACKGROUND

Escherichia coli (E. coli) is a frequent uropathogen in urinary tract infections (UTI). Widespread resistance to sulfamethoxazole-trimethoprim (SMX-TMP) and increasing resistance to fluoroquinolones amongst these isolates has been recognized. There are limited data demonstrating risk factors for resistance to both SMX-TMP and fluoroquinolones.

OBJECTIVE

This study was conducted to assess for the prevalence of community resistance amongst E. coli isolates to SMX-TMP and levofloxacin in ambulatory patients discharged from the emergency department (ED).

METHODS

Adults presenting for evaluation and discharged from the ED with a diagnosis of an E. coli UTI were retrospectively reviewed. Utilizing demographic and clinical data the prevalence of E. coli resistance and risk factors associated with SMX-TMP- and fluoroquinolone-resistant infection were determined.

RESULTS

Among the 222 patients, the mean rates of E. coli susceptibility to levofloxacin and SMX-TMP were 82.4% and 72.5%, respectively. Significant risk factors for resistance to SMX-TMP included prior antibiotic use (p=0.04) and prior diagnosis of UTI (p= 0.01). Significant risk factors for resistance to levofloxacin included: male gender, age, presence of hypertension, diabetes, chronic respiratory disease, nursing home resident, previous antibiotic use, previous diagnosis of UTI, existence of renal or genitourinary abnormalities, and prior surgical procedures (p <0.05 for all comparisons). The number of hospital days prior to initial ED evaluation (p<0.001) was determined to be a predictive factor in hospital and ED readmission.

CONCLUSIONS

These results suggest that conventional approaches to monitoring for patterns of susceptibility may be inadequate. It is imperative that practitioners develop novel approaches to identifying patients with risk factors for resistance. Identification of risk factors from this evaluation should prompt providers to scrutinize the use of these agents in the setting of patients presenting with an uncomplicated UTI in the ED.

Fluoroquinolone resistance among gram-negative urinary tract pathogens: global smart program results, 2009-2010

OBJECTIVES

To determine the rates of fluoroquinolone resistant (FQR) in gram-negative bacilli urinary tract infections (UTIs) in a global population.

METHODS

The Study for Monitoring Antimicrobial Resistance Trends (SMART) collected 1,116 FQR gram-negative urinary pathogens from hospitalized patients in 33 countries during 2009-2010. Amikacin, ertapenem, and imipenem were the most active agents tested against FQR UTI pathogens, including extended-spectrum beta-lactamase producers.

RESULTS

FQR rates vary widely country to country with a range of 6% to 75%. Regional FQR rates were 23.5% in North America, 29.4% in Europe, 33.2% in Asia, 38.7% in Latin America, and 25.5% in the South Pacific.

CONCLUSIONS

These observations suggest that fluoroquinolones may no longer be effective as first-line therapy for gram-negative UTI in hospitalized patients.

Incidence of antibiotic-resistant Escherichia coli bacteriuria according to age and location of onset: a population-based study from Olmsted County, Minnesota

OBJECTIVE

To better understand the epidemiology of drug-resistant Escherichia coli across health care and community settings.

PATIENTS AND METHODS

We conducted a population-based cohort study of the incidence of antibiotic-resistant E coli bacteriuria among different patient groups. All urine cultures with monomicrobial growth of E coli obtained from Olmsted County, Minnesota, residents from January 1, 2005, through December 31, 2009, were identified. The initial isolate per patient per year was included. Analyses were stratified by patient age and location of infection onset (ie, nosocomial, health care associated, and community associated).

RESULTS

We evaluated 5619 E coli isolates and the associated patients. During the study period, the incidence of drug-resistant bacteriuria did not change among children but increased significantly among adults of all ages, most markedly among elderly patients older than 80 years. In elderly patients, the incidence of bacteriuria with isolates resistant to fluoroquinolones increased from 464 to 1116 per 100,000 person-years (P<.001), and the incidence of bacteriuria with isolates resistant to fluoroquinolones plus trimethoprim-sulfamethoxazole increased from 274 to 512 per 100,000 person-years (P<.05). When analyzed by location of infection onset, incidence of bacteriuria with isolates resistant to trimethoprim-sulfamethoxazole, fluoroquinolones, trimethoprim-sulfamethoxazole plus fluoroquinolones, extended-spectrum cephalosporins, and more than 3 drug classes increased significantly among community-associated but not among nosocomial or health care-associated cases.

CONCLUSION

In this population-based study, the incidence of antibiotic-resistant E coli bacteriuria nearly doubled during the 5-year study period among elderly patients and those with community-associated isolates. These patient groups should be targets of interventions to slow the emergence and spread of antibiotic-resistant E coli.

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.

A clinical prediction rule for fluoroquinolone resistance in healthcare-acquired gram-negative urinary tract infection

Data from a case-control study were used to derive and internally validate a prediction rule for identifying fluoroquinolone resistance in healthcare-acquired gram-negative urinary tract infection. This prediction rule has an excellent sensitivity and specificity (C-statistic, 0.816). External validation is necessary before implementing this rule to optimize empirical antibiotic use in clinical practice.

Urinary tract infections in the elderly population

BACKGROUND

Urinary tract infections (UTIs) are a common problem in the elderly population. The spectrum of disease varies from a relatively benign cystitis to potentially life-threatening pyelonephritis.

OBJECTIVE

This review covers the management of asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, antibiotic resistance, catheter-associated bacteriuria/symptomatic UTIs, and antibiotic prophylaxis for recurrent infections in elderly men and women.

METHODS

Literature was obtained from English-language searches of MEDLINE (1966-April 2011), Cochrane Library, BIOSIS (1993-April 2011), and EMBASE (1970-April 2011). Further publications were identified from citations of resulting articles. Search terms included, but were not limited to, urinary tract infections, asymptomatic bacteriuria, acute uncomplicated cystitis, acute uncomplicated pyelonephritis, antibiotic resistance, catheter associated urinary tract infections, recurrent urinary tract infections, and elderly.

RESULTS

The prevalence of UTIs in elderly women depends on the location in which these women are living. For elderly women living in the community, UTIs compromise the second most common infection, whereas in residents of long-term care facilities (LTCFs) and hospitalized subjects, it is the number one cause of infection. The spectrum of patient presentation varies from classic signs and symptoms in the independent elderly population to atypical presentations, including increased lethargy, delirium, blunted fever response, and anorexia. Although there are few guidelines specifically directed toward the management of UTIs in the elderly population, therapy generally mirrors the recommendations for the younger adult age groups. When choosing a treatment regimen, special attention must be given to the severity of illness, living conditions, existing comorbidities, presence of external devices, local antibiotic resistance patterns, and the ability of the patient to comply with therapy.

CONCLUSIONS

Improved guidelines for the diagnosis and management of UTIs in the elderly population are needed. Better techniques to evaluate and prevent catheter-associated bacteriuria and UTIs await improved diagnostic modalities and catheter technologies. Alternative methods for prophylaxis of patients who suffer from recurrent infections must be found while minimizing the risk of developing or propagating antibiotic resistance.

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

Past studies exploring risk factors for fluoroquinolone (FQ) resistance in urinary tract infections (UTIs) focused only on UTIs caused by Gram-negative pathogens. The epidemiology of FQ resistance in enterococcal UTIs has not been studied. We conducted a case-control study at two medical centres within the University of Pennsylvania Health System in order to identify risk factors for FQ resistance in enterococcal UTIs. Subjects with positive urine cultures for enterococci and meeting CDC criteria for healthcare-acquired UTI were eligible. Cases were subjects with FQ-resistant enterococcal UTI. Controls were subjects with FQ-susceptible enterococcal UTI and were frequency matched to cases by month of isolation. A total of 136 cases and 139 controls were included from 1 January 2003 to 31 March 2005. Independent risk factors [adjusted OR (95% CI)] for FQ resistance included cardiovascular diseases [2·24 (1·05-4·79), P=0·037], hospitalization within the past 2 weeks [2·08 (1·05-4·11), P=0·035], hospitalization on a medicine service [2·15 (1·08-4·30), P<0·030], recent exposure to β-lactamase inhibitors (BLIs) [14·98 (2·92-76·99), P<0·001], extended spectrum cephalosporins [9·82 (3·37-28·60), P<0·001], FQs [5·36 (2·20-13·05), P<0·001] and clindamycin [13·90 (1·21-10·49), P=0·035]. Use of BLIs, extended spectrum cephalosporins, FQs and clindamycin was associated with FQ resistance in enterococcal uropathogens. Efforts to curb FQ resistance should focus on optimizing use of these agents.