Epidemiology and frequency of resistance among pathogens causing urinary tract infections in 1,510 hospitalized patients: a report from the SENTRY Antimicrobial Surveillance Program (North America)

Bayesian estimation of the prevalence of antimicrobial resistance: a mathematical modelling study

BACKGROUND

Estimates of the prevalence of antimicrobial resistance (AMR) underpin effective antimicrobial stewardship, infection prevention and control, and optimal deployment of antimicrobial agents. Typically, the prevalence of AMR is determined from real-world antimicrobial susceptibility data that are time delimited, sparse, and often biased, potentially resulting in harmful and wasteful decision-making. Frequentist methods are resource intensive because they rely on large datasets.

OBJECTIVES

To determine whether a Bayesian approach could present a more reliable and more resource-efficient way to estimate population prevalence of AMR than traditional frequentist methods.

METHODS

Retrospectively collected, open-source, real-world pseudonymized healthcare data were used to develop a Bayesian approach for estimating the prevalence of AMR by combination with prior AMR information from a contextualized review of literature. Iterative random sampling and cross-validation were used to assess the predictive accuracy and potential resource efficiency of the Bayesian approach compared with a standard frequentist approach.

RESULTS

Bayesian estimation of AMR prevalence made fewer extreme estimation errors than a frequentist estimation approach [n = 74 (6.4%) versus n = 136 (11.8%)] and required fewer observed antimicrobial susceptibility results per pathogen on average [mean = 28.8 (SD = 22.1) versus mean = 34.4 (SD = 30.1)] to avoid any extreme estimation errors in 50 iterations of the cross-validation. The Bayesian approach was maximally effective and efficient for drug-pathogen combinations where the actual prevalence of resistance was not close to 0% or 100%.

CONCLUSIONS

Bayesian estimation of the prevalence of AMR could provide a simple, resource-efficient approach to better inform population infection management where uncertainty about AMR prevalence is high.

Rise of the beta-lactams: a retrospective, comparative cohort of oral beta-lactam antibiotics as step-down therapy for hospitalized adults with acute pyelonephritis

Objective

The aim of this study was to determine if oral beta-lactam therapy is non-inferior to alternative therapy at discharge following inpatient treatment with an IV cephalosporin for acute pyelonephritis.

Design

Institutional Review Board (IRB)-approved, multicenter, retrospective, non-inferiority cohort (15% non-inferiority margin).

Setting

Six hospitals within two healthcare systems.

Patients

Hospitalized patients admitted to the medical floor with acute pyelonephritis without urologic abnormalities who received cefazolin or ceftriaxone followed by step-down therapy.

Methods

Patients were discharged with either an oral beta-lactam or an oral alternative agent (ie, fluoroquinolone or trimethoprim-sulfamethoxazole) to complete therapy. The primary objective was treatment failure defined as a composite of hospital readmission or an ED visit for a urinary cause within 30 days of discharge of the index hospitalization. Data were extracted manually from the electronic medical record.

Results

A total of 211 patients were included; 122 received an oral beta-lactam and 89 received an oral alternative agent at discharge. There was no difference in 30-day treatment failure between the two groups (4.9% vs 5.6% for oral beta-lactams vs oral alternatives, respectively. Absolute difference = 0.7%; 95% CI -5.4% to 6.8%; P = .82). The median length of hospital stay, number of patients treated with intravenous ceftriaxone, duration of IV therapy, and median duration of oral therapy were no different between groups.

Conclusions

In non-ICU patients admitted for pyelonephritis without urologic abnormalities, oral beta-lactams were non-inferior to oral alternatives for step-down therapy. In finding non-inferiority between the regimens, we show the feasibility of administering oral beta-lactams to complete therapy for acute pyelonephritis.

Exploring the Dynamic Role of Bacterial Etiology in Complicated Urinary Tract Infections

Background and Objectives. Numerous studies have been conducted to explore the epidemiological characteristics of urinary tract infections (UTI) and sepsis. However, there is still a lack of relevant bacteriological features and prognostic information regarding urosepsis based on bacteriological etiology. The current study aims to evaluate the bacterial etiology of complicated UTI (cUTI) and bacterial resistance to antibiotics and whether they present an intrinsic risk of developing urosepsis. Materials and Methods. A retrospective study was performed that included 102 patients who were diagnosed with cUTI and admitted to the urology department of the "Sfântul Apostol Andrei" County Emergency Clinical Hospital (GCH) from September 2019 to May 2022. Results. A considerable number of patients, n = 41 (40.2%), were diagnosed with multi drug-resistant (MDR) infection. Escherichia coli (E. coli) was identified as the prevailing pathogen, accounting for 51 patients. Klebsiella manifested itself as the subsequent causative agent in 27 instances. The presence of Enterococcus spp. infection was documented in 13 patients, whereas Pseudomonas emerged as the etiological perpetrator in the clinical context of 8 patients. The current study found a substantial prevalence of resistance to first-line antibiotics. The overall resistance rate was 74.5% for penicillin, 58.82% for trimethoprim-sulfamethoxazole and 49% for fluoroquinolones; cephalosporin resistance displayed an inverse correlation with antibiotic generation with fourth-generation cephalosporins exhibiting a resistance rate of 24.5%, and first-generation cephalosporins demonstrating a resistance rate of 35.29%. Conclusions. Age, comorbidities and indwelling urinary catheters are risk factors for developing MDR infections. While the intrinsic characteristics of the causative bacterial agent in cUTI may not be a risk factor for developing urosepsis, they can contribute to increased mortality risk. For empiric antibiotic treatment in patients with cUTI who are at a high risk of developing urosepsis and experiencing a potentially unfavorable clinical course, broad-spectrum antibiotic therapy is recommended. This may include antibiotics, such as amikacin, tigecycline, carbapenems and piperacillin-tazobactam.

Allele distribution and phenotypic resistance to ciprofloxacin and gentamicin among extended-spectrum β-lactamase-producing Escherichia coli isolated from the urine, stool, animals, and environments of patients with presumptive urinary tract infection in Tanzania

Background

Additional antimicrobial resistance to extended-spectrum β-lactamase (ESBL)-producing E. coli exhausts treatment options. We investigated allele distribution and resistance to ciprofloxacin and gentamicin among ESBL-producing E. coli isolates from the urine, stool, animals, and environments of presumptive urinary tract infection (UTI) patients, in order to gain a crucial insight toward devising prevention and control measures and treatment guidelines.

Methods

Archived ESBL-producing E. coli isolates from the urine, stool, animals, and surrounding environments of presumptive UTI patients were retrieved. Antimicrobial susceptibility profiles for ciprofloxacin and gentamicin were done followed by multiplex Polymerase chain reaction (PCR) for blaCTX-M , blaTEM , and blaSHV , to determine ESBL allele distribution. Data were analyzed using STATA version 17.

Results

A total of 472 confirmed ESBL-producing E. coli isolates from Mwanza 243 (51.5%), Kilimanjaro 143 (30.3%), and Mbeya 86 (18.2%) were analyzed. Of these, 75 (15.9%) were from urine, 199 (42.2%) from stool, 58 (12.3%) from rectal/cloaca swabs of animals, and 140 (29.7%) from surrounding environments. Out of the 472 ESBL-producing E. coli, 98.9% (467) had at least one ESBL allele. The most frequent allele was blaCTX-M , which was detected in 88.1% (416/472) of isolates, followed by the blaTEM allele, which was detected in 51.5% (243/472) of isolates. A total of 40.7% (192/472) of isolates harbored dual blaCTX-M  + blaTEM alleles and only 0.2% (1/472) of isolates had dual blaCTX-M  + blaSHV alleles, whereas 2.3% (11/472) of isolates had a combination of all three alleles (blaCTX-M  + blaTEM  + blaSHV ). None of the isolates harbored a combination of blaTEM  + blaSHV only. Resistance to ciprofloxacin and gentamicin was observed in 70.8% (334/472) and 46.0% (217/472) of isolates, respectively. There was a significant difference in the distribution of resistance to ciprofloxacin as well as gentamicin among ESBL-producing E. coli isolated from various sources (p-value < 0.001 and 0.002, respectively).

Conclusion

Almost all ESBL-producing E. coli isolates carry blaCTX-M , blaTEM , and blaSHV either alone or in combination, with the most common allele being blaCTX-M. The resistance to ciprofloxacin and gentamicin, which are frontline antibiotics for UTIs among ESBL-producing E. coli, is high. This implies the need to continually revise the local guidelines used for optimal empirical therapy for UTIs, and for continual research and surveillance using one health approach.

Monitoring fluoroquinolone resistance among ESBL-positive and ESBL-negative Escherichia coli strains isolated from urinary tract infections: An alert for empirical treatment

BACKGROUND

Bacterial resistance to extended-spectrum beta-lactamases (ESBL) is present worldwide. Empirical antibiotic therapy is often needed, and the use of fluoroquinolones, such as ciprofloxacin and norfloxacin, is common. This study aimed to analyze the urine cultures from 2,680 outpatients in January 2019, 2020, 2021, and 2022, with bacterial counts above 100,000 CFU/mL in which Escherichia coli was the etiological agent.

METHODS

We monitored the resistance of ESBL-positive and ESBL-negative strains to ciprofloxacin and norfloxacin and evaluated resistance rates.

RESULTS

Significantly higher fluoroquinolone resistance rates were observed among ESBL-positive strains in all years studied. Furthermore, a significant increase in the rate of fluoroquinolone resistance was observed between 2021 and 2022 in ESBL-positive and -negative strains, as well as from 2020 to 2021 among the ESBL-positive strains.

CONCLUSIONS

The data obtained in the present study showed a tendency towards an increase in fluoroquinolone resistance among ESBL-positive and -negative E. coli strains isolated from urine cultures in Brazil. Since empirical antibiotic therapy with fluoroquinolones is commonly used to treat diverse types of infections, such as community-acquired urinary tract infections, this work highlights the need for continuous monitoring of fluoroquinolone resistance among E. coli strains circulating in the community, which can mitigate the frequency of therapeutic failures and development of widespread multidrug-resistant strains.

Antibiotic Antibiogram in Patients With Complicated Urinary Tract Infections in Nephrology Unit of South Waziristan

Objectives

To evaluate the antibiotic antibiogram in patients with complicated urinary tract infections (cUTIs) presenting to a Nephrology unit of South Waziristan.

Methods

A cross-sectional study was conducted at the Department of Nephrology, Sholam, South Waziristan. The study included all patients who presented with cUTIs and the symptoms included urinary urgency, hematuria, dysuria, suprapubic discomfort, and increased frequency. Those patients with clinical manifestations but are on antibiotics within the past five days were excluded.

Results

A total of 158 patients were included in the study with 113 (71.5%) females and 45 (28.5%) males. A total of 95 (60%) cases had gram-negative microbes, 47 (30%) had gram-positive cocci, and 16 (10%) had candida infection. In our study, the highly prevalent uropathogenic gram-positive bacteria showed the highest sensitivity to Linezolid, Rifampicin, and Vancomycin. Methicillin-resistant staph aureus was detected in 25% of isolates. All isolates of candida were sensitive to fluconazole. Gram-negative bacteria were highly resistant to ceftazidime, cefepime, ceftriaxone, and ciprofloxacin.

Conclusion

The development of bacterial resistance against multiple antibiotics is a global crisis that restricts the drug of choice for the treatment of cUTIs. In our study, we showed that overall, E.coli (gram negative) and S. Aureus (gram-positive) showed variable resistance to many antibiotics including ceftazidime, cefepime, piperacillin-tazobactam, ceftriaxone, and clindamycin.

A Method to Determine the Efficacy of a Commercial Phage Preparation against Uropathogens in Urine and Artificial Urine Determined by Isothermal Microcalorimetry

Background: Urinary tract infections are commonly encountered and often treated with antibiotics. However, the inappropriate use of the latter has led to the appearance of resistant strains. In this context we investigate the use of calorimetry to rapidly determine if a phage cocktail can be used as alternative to antibiotics. Methods: We used a commercially available phage cocktail from an online pharmacy and tested it against a strain of Escherichia coli and a strain of Proteus mirabilis. We used isothermal microcalorimetry to follow the metabolic activity of the bacterial culture treated with the phage cocktail. Results: Isothermal microcalorimetry was able to follow the dynamic of the bacterial metabolic activity reduction by the phage cocktail. Both pathogens were strongly inhibited; however, some regrowth was observed for E. coli in urine. Conclusions: Isothermal microcalorimetry proved to be a valuable technique when investigating the efficacy of phage cocktails against uropathogens. We foresee that isothermal microcalorimetry could be used to obtain rapid phagograms.

Antibiotic Resistance Pattern of Uropathogens among Non Pregnant Women: A Hospital based Cross Sectional Study from Odisha

Urinary tract infection (UTI) is one of the most delicate health problem affecting women with severe complications and the rising antimicrobial resistance exerts a massive influence in treating UTIs. The objectives of this study was to identify the uropathogens causing UTI in non-pregnant women and their antibiotic resistance pattern. The study was undertaken in the outpatient department (OPD) of Obstetrics and Gynaecology, Capital Hospital, Bhubaneswar, Odisha during April 2015 to March 2016. A total of 766 midstream urine samples (MSU) was collected from women of different age. Out of 766 urine samples, 323 (42.1%) samples were culture positive for UTI with prominent bacteriuria. E.coli was found to be the most common isolate (54.79 %) followed by Staphylococcus sp. (22.6%), Enterobacter sp. (17.64%) and Klebsiella sp. (4.95%). Amongst various clinical symptoms, burning and itching during urination was found to be the most common (69.97%) symptoms followed by abnormal discharge of the vagina (45.20%) and the presence of cloudy urine (24.46%). E.coli the most predominant uropathogen identified was found to be highly susceptible towards a low level of resistance towards nitrofurantoin (11.8%) followed by amikacin (20.03%) and gentamicin (22.0%). Our study revealed that E. coli isolates were the predominant uropathogens and showed escalating model of resistance to the general available antimicrobial agents which are frequently used by the physicians in hospitals and private practice.

Antimicrobial Resistance Patterns and ESBL of Uropathogens Isolated from Adult Females in Najran Region of Saudi Arabia

Background: To explore the prevalence of urinary tract infections (UTIs) among female patients in the Najran region of Saudi Arabia and determine their antimicrobial resistance pattern. Methods: This study was conducted on 136 urine samples collected from outpatient departments (OPDs) of the different government hospitals in the Najran region of Saudi Arabia. Over one year, the results of susceptibility testing reports of outpatient midstream urine samples from three government hospitals were prospectively evaluated. Results: Of 136 urine samples, only 123 (90.45%) were found to show significant growth for UTIs, from which 23 different uropathogens were identified. Escherichia coli (58.5%) was the most commonly isolated organism, followed by Klebsiella pneumoniae (8.1%). The isolated microorganism showed increased resistance patterns from 3.3% to 62.6%, with an overall resistance of 27.19%. Meropenem was the most effective antimicrobial, followed by amikacin and ertapenem (0.47%, 0.91%, and 1.5% resistance, respectively). At the same time, ampicillin and cephazolin were the least (62.6% and 59.5% resistance, respectively) effective. Overall, eleven (8.94%) uropathogens isolates were ESBLs, among which there were eight (6.5%) Escherichia coli, one (0.81%) Klebsiella pneumoniae, one (0.81%) Klebsiella oxytoca, and one (0.81%) Citrobacter amalonaticus. Conclusions: E. coli remains the most commonly isolated causative uropathogens, followed by Klebsiella species. The prevalence of pathogenic E. coli and Klebsiella species underscores the importance of developing cost-effective, precise, and rapid identification systems to minimize public exposure to uropathogens. Antibiotic susceptibility data revealed that most of the isolates were resistant to the majority of the antibiotics. The patients with UTIs in the Najran region of Saudi Arabia are at a high risk of antibiotic resistance, leading to significant problems in outpatient department (OPD) treatment outcomes and raising the alarm for the physician to change their empiric treatment.

Change in antimicrobial susceptibility of pathogens isolated from surgical site infections over the past decade in Japanese nation-wide surveillance study

Inappropriate antimicrobial therapy for surgical site infections (SSIs) can lead to poor outcomes and an increased risk of antibiotic resistance. A nationwide survey was conducted in Japan from 2018 to 2019 to investigate the antimicrobial susceptibility of pathogens isolated from SSIs. The data were compared with those obtained in 2010 and 2014-2015 surveillance studies. Although the rate of detection of extended-spectrum β-lactamase producing strains of Escherichia coli was increased from 9.5% in 2010 to 23% in 2014-2015, the incidence decreased to 8.7% in 2018-2019. Although high susceptibility rates were detected to piperacillin/tazobactam (TAZ), the geometric mean MICs were substantially higher than to meropenem (2.67 vs 0.08 μg/mL). By contrast, relatively low geometric mean MICs (0.397 μg/mL) were demonstrated for ceftolozane/TAZ. Although the MRSA incidence rate decreased from 72% in the first surveillance to 53% in the second, no further decrease was detected in 2018-2019. For the Bacteroides fragilis group species, low levels of susceptibility were observed for moxifloxacin (65.3%), cefoxitin (65.3%), and clindamycin (CLDM) (38.9%). In particular, low susceptibility against cefoxitin was demonstrated in non-fragilis Bacteroides, especially B. thetaiotaomicron. By contrast, low susceptibility rates against CLDM were demonstrated in both B. fragilis and non-fragilis Bacteroides species, and a steady decrease in susceptibility throughout was observed (59.3% in 2010, 46.9% in 2014-2015, and 38.9% in 2018-2019). In conclusion, Japanese surveillance data revealed no significant lowering of antibiotic susceptibility over the past decade in organisms commonly associated from SSIs, with the exception of the B. fragilis group.

Risk factors for enterococcal urinary tract infections: a multinational, retrospective cohort study

Complicated urinary tract infection (cUTI) is a frequent cause of morbidity. In this multinational retrospective cohort study, we aimed to demonstrate risk factors for enterococcal UTI. Univariate and multivariate analyses of risk factors for enterococcal infection were performed. Among 791 hospitalized patients with cUTI, enterococci accounted for approximately 10% of cases (78/791). Risk factors for enterococcal UTI in multivariable analysis were male gender, age range of 55-75 years, catheter-associated UTI, and urinary retention. This information may assist treating physicians in their decision-making on prescribing empiric anti-enterococcus treatment to hospitalized patients presenting with cUTI and thus improve clinical outcomes.

Antimicrobial and Antibiofilm Activities of Probiotic Lactobacilli on Antibiotic-Resistant Proteus mirabilis

The emergence of biofilm-forming, multi-drug-resistant (MDR) Proteus mirabilis infections is a serious threat that necessitates non-antibiotic therapies. Antibiotic susceptibility and biofilm-forming activity of P. mirabilis isolates from urine samples were assessed by disc diffusion and crystal violet assays, respectively. Antimicrobial activities of probiotic Lactobacilli were evaluated by agar diffusion. Antibiofilm and anti-adherence activities were evaluated by crystal violet assays. While most P. mirabilis isolates were antibiotic-resistant to varying degrees, isolate P14 was MDR (resistant to ceftazidime, cefotaxime, amoxicillin-clavulanic acid, imipenem, ciprofloxacin, and amikacin) and formed strong biofilms. Cultures and cell-free supernatants of Lactobacillus casei and Lactobacillus reuteri exhibited antimicrobial and antibiofilm activities. The 1/16 concentration of untreated supernatants of L. casei and L. reuteri significantly reduced mature biofilm formation and adherence of P14 by 60% and 72%, respectively (for L. casei), and by 73% each (for L. reuteri). The 1/8 concentration of pH-adjusted supernatants of L. casei and L. reuteri significantly reduced mature biofilm formation and adherence of P14 by 39% and 75%, respectively (for L. casei), and by 73% each (for L. reuteri). Scanning electron microscopy (SEM) confirmed eradication of P14’s biofilm by L. casei. L. casei and L. reuteri could be utilized to combat Proteus-associated urinary tract infections.

Common microbial causes of significant bacteriuria and their antibiotic resistance pattern in the Isfahan Province of Iran

Urinary tract infections (UTIs) are considered the most common community-acquired infections worldwide, which have possible complications along with significant economic impact on national healthcare systems. The aim of this study was to identify the most common causes of significant bacteriuria and to assess their antimicrobial resistance pattern in the Isfahan province of Iran. In this cross-sectional study, 11,678 urine samples of the patients referred to Mahdieh Medical Diagnostic Centre Charity were examined over a period of 10 months (from September 2015 to June 2016). Among the cases, 6.85% were positive for bacteriuria (F/M = 11.3). Escherichia coli (62%) was the most frequently isolated bacteria, followed by Staphylococcus epidermidis (13.9%) and Staphylococcus aureus (6.8%). E. coli was more prevalent among patients with diabetes mellitus. E. coli isolates showed the highest resistance to nalidixic acid, Trimethoprim/Sulfamethoxazole and Cefixime. Our results revealed that broad-spectrum antibiotic resistance is frequent among isolated uropathogens in Isfahan, Iran.

Application of Next-Generation Sequencing for Characterization of Surveillance and Clinical Trial Isolates: Analysis of the Distribution of β-lactamase Resistance Genes and Lineage Background in the United States

Background

Sequencing technologies and techniques have seen remarkable transformation and innovation that have significantly affected sequencing capability. Data analyses have replaced sequencing as the main challenge. This paper provides an overview on applying next-generation sequencing (NGS) and analysis and discusses the benefits and challenges. In addition, this document shows results from using NGS and bioinformatics tools to screen for β-lactamase genes and assess the epidemiological structure of Escherichia coli– and Klebsiella pneumoniae–causing bloodstream (BSIs) and urinary tract (UTIs) infections in patients hospitalized in the United States during the SENTRY Antimicrobial Surveillance Program for 2016.

Methods

A total of 3525 isolates (2751 E. coli and 774 K. pneumoniae) causing BSIs (n = 892) and UTIs (n = 2633) in hospitalized patients in the United States were included. Isolates were tested for susceptibility by broth microdilution, and those that met a minimum inhibitory concentration (MIC)–based screening criteria had their genomes sequenced and analyzed.

Results

A total of 11.6% and 16.1% of E. coli–causing UTIs and BSIs, respectively, met the MIC-based criteria, whereas 11.0% and 13.7% of K. pneumoniae isolates causing UTIs and BSIs, respectively, met the criteria. Among E. coli, bla_CTX-M variants (87.6% overall) prevailed (60.5% of CTX-M group 1 and 26.9% of group 9). A total of 60.3% of K. pneumoniae isolates carried bla_CTX-M variants (52.7% and 7.6% of groups 1 and 9, respectively). Two E. coli (0.6%) and 13 K. pneumoniae (12.9%) isolates harbored bla_KPC. Among KPC-producing K. pneumoniae (2 from BSIs and 11 from UTIs), 84.6% (11/13) were ST258 (CC258). Seventeen and 38 unique clonal complexes (CCs) were noted in E. coli that caused BSIs and UTIs, respectively, and CC131 (or ST131) was the most common CC among BSI (53.6%) and UTI (58.2%) isolates. Twenty-three and 26 CCs were noted among K. pneumoniae–causing BSIs and UTIs, respectively. CC258 (28.3%) prevailed in UTI pathogens, whereas CC307 (15.0%) was the most common CC among BSI isolates.

Conclusions

This study provides a benchmark for the distribution of β-lactamase genes and the population structure information for the most common Enterobacteriaceae species responsible for BSIs and UTIs in US medical centers during the 2016 SENTRY Program.

Urinary tract infection: Pathogenicity, antibiotic resistance and development of effective vaccines against Uropathogenic Escherichia coli

Urinary tract infections (UTIs) are recognized as one of the most common infectious diseases in the world that can be divided to different types. Uropathogenic Escherichia coli (UPEC) strains are the most prevalent causative agent of UTIs that applied different virulence factors such as fimbriae, capsule, iron scavenger receptors, flagella, toxins, and lipopolysaccharide for their pathogenicity in the urinary tract. Despite the high pathogenicity of UPEC strains, host utilizes different immune systems such as innate and adaptive immunity for eradication of them from the urinary tract. The routine therapy of UTIs is based on the use of antibiotics such as β-lactams, trimethoprim, nitrofurantoin and quinolones in many countries. Unfortunately, the widespread and misuse of these antibiotics resulted in the increasing rate of resistance to them in the societies. Increasing antibiotic resistance and their side effects on human body show the need to develop alternative strategies such as vaccine against UTIs. Developing a vaccine against UTI pathogens will have an important role in reduction the mortality rate as well as reducing economic costs. Different vaccines based on the whole cells (killed or live-attenuated vaccines) and antigens (subunits, toxins and conjugatedvaccines) have been evaluated against UTIs pathogens. Furthermore, other therapeutic strategies such as the use of probiotics and antimicrobial peptides are considered against UTIs. Despite the extensive efforts, limited success has been achieved and more studies are needed to reach an alternative of antibiotics for treatment of UTIs.

Prevalence of Multidrug Resistance and Extended-Spectrum β-Lactamase Carriage of Clinical Uropathogenic Escherichia coli Isolates in Riyadh, Saudi Arabia

The prevalence of extended-spectrum β-lactamase-producing Escherichia coli (ESBL-producing E. coli) has recently increased worldwide. This study aims at determining the antimicrobial susceptibility patterns of a collection of clinical E. coli urine isolates and evaluating the ESBL carriage of these isolates at phenotypic and genotypic levels. A total of 100 E. coli urine isolates were collected at a tertiary healthcare centre in Riyadh from January 2018 to March 2018. Antimicrobial susceptibility testing was carried out for all isolates. ESBL production was characterized at phenotypic and genotypic levels using double-disc synergy test and polymerase chain reaction, respectively. Detection of different ESBL variants was performed using DNA sequencing. Of 100 E. coli isolates, 67 were associated with multidrug resistance (MDR) phenotype. All isolates showed variable resistance levels to all antibiotics used here expect to imipenem, where they were all imipenem-sensitive. 33 out of 100 E. coli isolates were positive for ESBLs by phenotypic and genotypic methods. Among all ESBL-positive E. coli isolates, the CTX-M was the most prevalent ESBL type (31/33 isolates; 93.94%). CTX-M-15 variant was detected in all isolates associated with CTX-M carriage. Multiple ESBL gene carriage was detected in 15/33 isolates (45.45%), where 11 (33.33%) isolates produced two different ESBL types while 4 isolates (12.12%) associated with carrying three different ESBL types. Our study documented the high antimicrobial resistance of ESBL-producing E. coli to many front-line antibiotics currently used to treat UTI patients, and this implies the need to continuously revise the local guidelines used for optimal empirical therapy for UTI patients. It also showed the high prevalence of ESBL carriage in E. coli urine isolates, with CTX-M-15 being the most predominant CTX-M variant.

Impact of Allergy and Resistance on Antibiotic Selection for Recurrent Urinary Tract Infections in Older Women

OBJECTIVES

To review the impact of antibiotic allergy and resistance in older women with recurrent urinary tract infections (RUTIs) as determinants for a suitable oral antibiotic treatment choice.

METHODS

A prospectively maintained database of women 65 years old and older with documented RUTIs (≥3 UTI/y) and trigonitis on cystoscopy was reviewed. Demographic data, known drug allergies, renal function, antibiotic susceptibility of most recent urine culture, allergy, or resistance to trimethoprim-sulfamethoxazole (TMP-SMX), fluoroquinolones, and nitrofurantoin were obtained.

RESULTS

From 2006 to 2014, 86 women with RUTIs met study criteria. Mean age was 77.9 ± 7.8, with 94% being Caucasian. An estimated glomerular filtration rate >30 mL/min was noted in 94%. The percentage of women allergic, resistant, or both allergic and resistant to TMP-SMX was 33%, 29%, and 15%, to fluoroquinolones was 14%, 34%, and 8.1%, or nitrofurantoin was 16%, 14%, and 5%, respectively. Twenty-eight percent (24 of 86) of women who were allergic and/or resistant to TMP-SMX and fluoroquinolones were sensitive to nitrofurantoin. Twenty percent (17 of 86) were allergic and/or resistant to all 3 antibiotics. Women who were allergic or resistant to TMP-SMX had a significantly higher number of other antibiotic resistances compared with women sensitive to TMP-SMX (4.9 ± 3.6 vs 2.1 ± 2.3; P < .0001). Similarly, women with fluoroquinolone allergy or resistance had significantly more antibiotic resistances than those who were fluoroquinolone sensitive (5.8 ± 3.5 vs 2.3 ± 2.5; P < .0001).

CONCLUSION

Because of allergy and/or antibiotic resistance, several first-line antibiotics are not available for many older women with RUTIs. In nearly a third of women, nitrofurantoin was the only viable alternative.

Determination immunogenic property of truncated MrpH.FliC as a vaccine candidate against urinary tract infections caused by Proteus mirabilis

Proteus mirabilis is common cause of urinary tract infections (UTIs) especially in complicated UTIs which are resistant to antibiotic therapy, Consequently, an ideal vaccine is inevitably required. The N-terminal domain of MrpH (Truncated form of MrpH) lies between the most critical antigens of P. mirabilis to consider as vaccine candidate. FliC of Salmonella typhimurium induces several pathways of immunity system, which leads to produce antibody and cytokines. In this study, adjuvant properties of FliC and efficacy of truncated MrpH as important antigen, in tMrpH.FliC were determined in in vitro and in vivo circumstances. Three proteins including: FliC, MrpH and tMrpH.FliC were injected to mice and subsequently sera and supernatant of cell culture were collected to evaluate different immune responses. According to our findings, tMrpH.FliC could stimulate both humoral and cellular immune responses, so that serum IgG, urine IgA, IL.4, IFN-γ and IL.17 were increased significantly in comparison to MrpH and FliC alone, this augmentation was considerable. Results showed significant decrease of bacterial load in all of the challenged groups compared to the control group, although this protective effect was the highest in mice vaccinated with tMrpH.FliC. Our results showed truncated MrpH, without an unwanted domain is an ideal vaccine target and FliC, as adjuvant, increases its immunogenic property. Thus, fusion protein tMrpH.FliC can be considered as promising vaccine against P. mirabilis.

A 6-year study of complicated urinary tract infections in southern China: prevalence, antibiotic resistance, clinical and economic outcomes

Urinary tract infections (UTIs) are common nosocomial infections. This study evaluated the prevalence, pathogens, antibiotic resistances, clinical outcomes, and hospitalization costs associated with complicated UTIs in southern China, and risk factors delaying patient discharge. We retrospectively reviewed electronic medical records of 4,284 (61.4% women) complicated UTI-related hospitalizations from 2008 to 2013. Average patient age was 61.1 years and median hospital stay was 11 days. Pathogens were isolated from 1,071 urine and 148 blood specimens. Gram-negative bacteria were the most frequent and included Escherichia coli (48.2%), Klebsiella pneumoniae (9.5%), Pseudomonas aeruginosa (4.9%), and Proteus mirabilis (4.6%), while Enterococcus spp. (14.4%) was the most common Gram-positive bacteria causing UTIs. Both E. coli and K. pneumoniae showed high resistance rates (>45%) to wide-spectrum penicillins, cephalosporins, aztreonam, and ciprofloxacin. Resistances to beta-lactamase inhibitor/beta-lactam antibiotic combination were relatively lower. Imipenem, meropenem, and amikacin had the greatest activity against E.coli and K. pneumoniae. Recurrent infection was a risk factor for mortality. Age, sex, previous surgery, diabetes, and renal insufficiency were significant risk factors for delayed discharge (P<0.01). Response to initial treatment was associated with a lower cost. Initial empiric use of antibiotics least associated with resistance may reduce costs and medical resource usage.

Species distribution and antibiotic susceptibility profile of bacterial uropathogens among patients complaining urinary tract infections

BACKGROUND

Urinary tract infection is the second most common type of infection and the problem is further compounded by the emergence of drug resistance in bacterial uropathogens. The aim of this study was to determine the spectrum of bacterial uropathogens and their drug resistant pattern.

METHODS

A single institutional cross-sectional study was carried out at Arsho Advanced Medical laboratory from September 2015 to May 2016. A total of 712 urine samples were collected, inoculated onto primary isolation culture media, incubated at 37 °C for 18-24 h, and significant bacteriuria was determined. Identification and the antimicrobial susceptibility testing of bacteria were determined by using the automated VITEK 2 compact system.

RESULTS

Out of 712 urine samples processed, 256 (36%) yielded significant bacteriuria of which 208 (81.25%) were obtained from female and 48 (18.75%) from male patients. Age group of 25-44 were more affected with the infection. Of 256 bacterial isolates recovered, Escherichia coli, was the dominant bacterium. Ampicillin and trimethoprim/sulfamethoxazole were the least effective drugs while piperacillin/tazobactam was the most effective drug against Gram-negative bacteria. Erythromycin was the least effective drug while vancomycin was the most active drug against Gram-positive bacteria.

CONCLUSIONS

Observation of many bacterial species causing UTI in this study warrants, a continuous epidemiological survey of UTI in health institutions across the country. High level of drug resistance to the commonly prescribed drugs necessitates a search for other options.

Gastrointestinal Carriage Is a Major Reservoir of Klebsiella pneumoniae Infection in Intensive Care Patients

BACKGROUND

Klebsiella pneumoniae is an opportunistic pathogen and leading cause of hospital-associated infections. Intensive care unit (ICU) patients are particularly at risk. Klebsiella pneumoniae is part of the healthy human microbiome, providing a potential reservoir for infection. However, the frequency of gut colonization and its contribution to infections are not well characterized.

METHODS

We conducted a 1-year prospective cohort study in which 498 ICU patients were screened for rectal and throat carriage of K. pneumoniae shortly after admission. Klebsiella pneumoniae isolated from screening swabs and clinical diagnostic samples were characterized using whole genome sequencing and combined with epidemiological data to identify likely transmission events.

RESULTS

Klebsiella pneumoniae carriage frequencies were estimated at 6% (95% confidence interval [CI], 3%-8%) among ICU patients admitted direct from the community, and 19% (95% CI, 14%-51%) among those with recent healthcare contact. Gut colonization on admission was significantly associated with subsequent infection (infection risk 16% vs 3%, odds ratio [OR] = 6.9, P < .001), and genome data indicated matching carriage and infection isolates in 80% of isolate pairs. Five likely transmission chains were identified, responsible for 12% of K. pneumoniae infections in ICU. In sum, 49% of K. pneumoniae infections were caused by the patients' own unique strain, and 48% of screened patients with infections were positive for prior colonization.

CONCLUSIONS

These data confirm K. pneumoniae colonization is a significant risk factor for infection in ICU, and indicate ~50% of K. pneumoniae infections result from patients' own microbiota. Screening for colonization on admission could limit risk of infection in the colonized patient and others.

Antimicrobial susceptibility of pathogens isolated from surgical site infections in Japan: Comparison of data from nationwide surveillance studies conducted in 2010 and 2014-2015

A nationwide survey was conducted in Japan from 2014 to 2015 to investigate the antimicrobial susceptibility of pathogens isolated from surgical site infections (SSI). The resulting data were compared with that obtained in an earlier survey, conducted in 2010. Seven main organisms were collected, and 883 isolates were studied. A significant reduction in methicillin resistance was observed among Staphylococcus aureus isolates, dropping from 72.5% in 2010 to 53.8% in 2014-2015 (p < 0.001). MRSA isolates with a vancomycin minimum inhibitory concentration (MIC) of 2 μg/mL accounted for 1.2% of all MRSA isolates, which was significantly lower than in 2010 (9.7%, p = 0.029). Of the Escherichia coli isolates, 23.0% produced an extended spectrum β-lactamase (ESBL) in the 2014-2015 survey, which was a significant increase from 9.5% in 2010 (p = 0.011). The geometric mean MICs for ESBL-producing isolates were 0.07 μg/mL for meropenem, 9.51 μg/mL for tazobactam/piperacillin, 0.15 μg/mL for flomoxef, and 1.56 μg/mL for gentamycin. There was a significant increase in the isolation rate of non-fragilis Bacteroides among Bacteroides fragilis group species between the two study periods (35.2% vs. 53.1%, p = 0.007). More than 90% of isolates belonging to the B. fragilis group remained susceptible to tazobactam/piperacillin, meropenem, and metronidazole. In contrast, lower levels of susceptibility were observed for cefmetazole (49.6%), moxifloxacin (61.9%), and clindamycin (46.9%). Non-fragilis Bacteroides isolates had lower rates of antibiotic susceptibility compared with B. fragilis. Overall, the surveillance data clarified trends in antimicrobial susceptibility for organisms commonly associated with SSI.

Fluoroquinolone and Third-Generation-Cephalosporin Resistance among Hospitalized Patients with Urinary Tract Infections Due to Escherichia coli: Do Rates Vary by Hospital Characteristics and Geographic Region?

This analysis of nearly 10,000 hospital-associated urinary tract infection (UTI) episodes due to Escherichia coli showed that fluoroquinolone and third-generation-cephalosporin resistance rates were 34.5% and 8.6%, respectively; the rate of concurrent resistance to both agents was 7.3%. Fluoroquinolone resistance rates exceeded 25% regardless of geographic location or hospital characteristics. The findings suggest that fluoroquinolones should be reserved and third-generation cephalosporins be used with caution as empirical agents for hospitalized patients with UTIs due to E. coli.

A retrospective study of the changing trends of antimicrobial resistance of Klebsiella pneumoniae isolated from urine samples over last 3 years (2012-2014)

Background:

In our country, the problem of antibiotic resistance is compounding because of overuse and misuse of antibiotics. There is no systematic national surveillance of antibiotic resistance and insufficient data are available to quantify the problem.

Objectives:

To study the changing pattern of antimicrobial resistance of Klebsiella pneumoniae isolates from patients of urinary tract infections over last 3 years.

Materials and Methods:

A retrospective, record-based study carried out based on the records culture sensitivity reports of indoor patients, during past 3 years (2012-2014). The type of organisms most common in urine sample was noted, and the drugs still effective for the particular organism were noted.

Results:

Klebsiella was the second most frequent isolate throughout the 3 years (14%) of the total isolates). Analysis of the results year wise indicated that the lowest percentage of resistance was manifested against imipenem between 11.94% (2012) and 13.75% (2014). Over the successive years, resistance to ceftriaxone tends to increase from 74.95 % (2012) to 81% (2014). Klebsiella showed very high resistance 90.78% (2012) and 95.63% (2012) to co-trimoxazole and tetracycline, respectively with increasing trend to absolute resistance to both groups over the 3 years period. On an average over the 3 years Klebsiella showed a high amount of resistances to fluoroquinolones (72.71%) and aminoglycosides (76.22%). While multi-drug resistant Klebsiella range between 65% (2012) and 67% (2014).

Conclusion:

The antimicrobial resistance patterns are constantly evolving and vary from region to region it has become a necessity to do constant antimicrobial sensitivity surveillance. This will help clinicians to provide safe and effective empirical therapies.

Are first-generation cephalosporins obsolete? A retrospective, non-inferiority, cohort study comparing empirical therapy with cefazolin versus ceftriaxone for acute pyelonephritis in hospitalized patients

OBJECTIVES

Literature is lacking regarding the utilization of first-generation cephalosporins for the treatment of acute pyelonephritis. The aim of this study was to determine whether cefazolin is non-inferior to ceftriaxone for the empirical treatment of acute pyelonephritis in hospitalized patients. The primary outcome included a composite of symptomatic resolution plus either defervescence at 72 h or normalization of serum white blood cell count at 72 h (non-inferiority margin 15%). Secondary outcomes included length of stay and 30 day readmission. A subgroup analysis of the composite outcome was also conducted for imaging-confirmed pyelonephritis.

METHODS

This was a retrospective, non-inferiority, multicentre, cohort study comparing cefazolin versus ceftriaxone for the empirical treatment of acute pyelonephritis in hospitalized patients.

RESULTS

Overall, 184 patients received one of the two treatments between July 2009 and March 2015. The composite outcome was achieved in 80/92 (87.0%) in the cefazolin group versus 79/92 (85.9%) in the ceftriaxone group (absolute difference 1.1%, 95% CI -11.1% to 8.9%, P = 0.83), meeting the pre-defined criteria for non-inferiority. The composite outcome for patients with imaging-confirmed pyelonephritis was achieved in 46/56 (82.1%) versus 42/50 (84.0%) for the cefazolin group and the ceftriaxone group, respectively (absolute difference 1.9%, 95% CI -12.8% to 16.5%, P = 0.80). Additionally, there were no statistically significant differences in length of stay or 30 day readmission for cystitis or pyelonephritis.

CONCLUSIONS

Cefazolin was non-inferior to ceftriaxone with regard to clinical response for the treatment of hospitalized patients with acute pyelonephritis in this study. No difference was observed for length of stay or 30 day readmission.

Incidence of antibiotics resistance among uropathogens in Omani children presenting with a single episode of urinary tract infection

Urinary tract infection (UTI) is one of the most common community-acquired infections. Different organisms can be the cause of UTI in children, with resistance to antibiotics becoming a significant problem in the choice of treatment. Worldwide studies have documented the prevalence of uropathogens in different countries. However, there is no previous study documenting the incidence of different uropathogens in Oman. We aim to report the most common uropathogens and their antibiotic sensitivity patterns in children presenting with documented, single episode UTI at a tertiary hospital in Oman. A retrospective analysis of all Omani children below 14 years who presented with a case of first documented UTI to SQUH between September 2008 and August 2012 was conducted. Data were obtained from the patients' electronic records in the hospital information system. Data were then analyzed using SSPS (Statistical Package for Social Sciences program, Version 20, IBM, Chicago, IL, USA). In the retrospective review of all urine cultures, 438 positive urine cultures were identified. Out of those, 208 (47.5%) belonged to children with their first episode of UTI. Thirty-three patients were excluded and 75 patients were included in the final analysis. Escherichia coli was the most frequently encountered uropathogen in our cohort (69%), followed by Klebsiella pneumoniae infection (17%). Nearly half (46.6%) of these two common organism were resistant to Cotrimoxazole, while 31% of them were resistant to Augmentin. Twenty-four percent of the E. coli and K. pneumoniae strains were resistant to Cefuroxime, and only 10% were resistant to nitrofurantoin. Both Augmentin and Cotrimoxazole should not be the first line antibiotics to treat UTI.

Acute Nosocomial Urinary Tract Infection in Children

The spectrum and antimicrobial susceptibilities of pathogens causing acute nosocomial urinary tract infection in hospitalized pediatric patients were revealed to be heterogeneous. Therefore, to avoid the failure of empirical antimicrobial therapy in these patients, underlying disease and previous antimicrobial treatment have to be considered.

[Antimicrobial susceptibility of uropathogens from uncomplicated urinary tract infection in a pediatric hospital]

BACKGROUND

Urinary tract infection in children is well recognized as a cause of acute morbidity and chronic medical conditions. As a result, appropriate use of antimicrobial agents, however, increases antibiotic resistance and complicates its treatment due to increased patient morbidity, costs, rates of hospitalization, and use of broader-spectrum antibiotics. The goal of this study was to determine antibiotic susceptibility to commonly used agents for urinary tract infection against recent urinary isolates.

METHODS

A total of 457 consecutive children attending the emergency room at the Hospital Infantil de México Federico Gómez with symptoms of uncomplicated lower urinary tract infection were eligible for inclusion. Patients who had had symptoms for≥7 days and those who had had previous episodes of urinary tract infection, received antibiotics or other complicated factors were excluded. Midstream and catheter urine specimens were collected. All isolates were identified and the in vitro activities of antimicrobials were determined.

RESULTS

The most frequently isolated urinary pathogens were as follows: Escherichia coli (E. coli) (312, 68.3%), Enterococcus spp. (42, 11%), Klebsiella pneumoniae (K. pneumoniae) (40, 8.7%), Pseudomonas aeruginosa (P. aeruginosa) (34, 7.5%), Proteus mirabilis (P. mirabilis) (21, 4.5%), Enterobacter cloacae (8, 1.7%). The resistance to trimetoprim/sulfametoxazol (%) was 73.7, 62.2, 100, 52, and 50, respectively, for E. coli, K. pneumoniae, P. aeruginosa, P. mirabilis and Enterobacter spp., 92.5 for Enterococcus faecalis (E. faecalis) and 49.9 for Enterococcus faecium (E. faecium). Ampicillin was 86.3, 45, 100, 47.9, and 66.6% for the same strains, ciprofloxacin 33.8, 9, 18.8, 0, 0%, nitrofurantoin 4.4, 13, 97.7, 70, 0%; to E. faecalis 0% and 16.7% to E. faecium.

CONCLUSIONS

Frequently prescribed empirical agents for uncomplicated urinary tract infection demonstrate lowered in vitro susceptibilities when tested against recent clinical isolates.

Retrospective analysis of antibiotic resistance pattern to urinary pathogens in a Tertiary Care Hospital in South India

CONTEXT

The distribution of uropathogens and their susceptibility pattern to antibiotics vary regionally and even in the same region, they change over time. Therefore, the knowledge on the frequency of the causative microorganisms and their susceptibility to various antibiotics are necessary for a better therapeutic outcome.

AIM

The aim was to study the frequency and distribution of uropathogens and their resistance pattern to antibiotics in a tertiary care hospital.

SETTINGS AND DESIGN

Retrospective study for a period of 1 year from January 2011 to December 2011 in a tertiary care hospital.

MATERIALS AND METHODS

The culture and sensitivity data of the uropathogens from suspected cases of UTI were collected from the records of Microbiology Department for study period. Midstream urine samples were processed for microscopy and culture, and the organisms were identified by standard methods. Antibiotic susceptibility was carried out by Kirby-Bauer disk diffusion method according to Clinical and Laboratory Standards Institute guidelines. Descriptive statistics were used to analyze the data.

RESULTS

Of 896 urine samples, 348 (38.84%) samples were positive for urine culture. Escherichia coli (52.59%) was the most common organism followed by Klebsiella. E. coli was least resistant to imipenem (8%) and amikacin (16%) and was highly resistant to co-trimoxazole (69%) and ampicillin (86%). Klebsiella species were least resistant to amikacin (26%) and were highly resistant to ampicillin (92%). The overall resistance pattern of antibiotics to uropathogens was the highest to nalidixic acid (79%) followed by co-trimoxazole (75%) and ampicillin (72%). Good susceptibility was seen with imipenem and cephalosporins.

CONCLUSION

E. coli is still the most common uropathogen. Nalidixic acid, ampicillin, co-trimoxazole, and first-generation fluoroquinolones have limited value for the treatment of UTI. Sensitivity to imipenem and amikacin are still retained and may be prescribed for complicated UTI. Routine monitoring of drug resistance pattern will help to identify the resistance trends regionally. This will help in the empirical treatment of UTIs to the clinicians.

The TIR Domain Containing Locus of Enterococcus faecalis Is Predominant among Urinary Tract Infection Isolates and Downregulates Host Inflammatory Response

Based on Toll/interleukin-1 receptor (TIR) domain structure homology, we detected a previously uncharacterized gene encoding for a TIR domain containing protein (Tcp) in the genome of Enterococcus faecalis. We assigned this gene the name tcpF (as in Tcp of E. faecalis). Screening of E. faecalis samples revealed that tcpF is more common in isolates from urinary tract infections (UTIs) than in human faecal flora. tcpF alleles showed moderate single nucleotide polymorphism (SNP) among UTI isolates. Infection of mouse RAW264.7 macrophages with a tcpF knock-out mutant led to elevated cytokine response compared to the isogenic wild type E. faecalis strain. In silico analysis predicted significant tertiary structure homology to the TIR domain of human TLR1 (TLR1-TIR). When transiently expressed in cultured eukaryotic cells, TcpF caused suppression of TLR2-dependent NF-κB activation suggesting for TcpF a role as a factor in E. faecalis that benefits colonization by modulating the host's immune responses.

Antimicrobial susceptibilities and clinical characterization of Pseudomonas aeruginosa isolates from urinary tract infections

INTRODUCTION

Pseudomonas aeruginosa is a uropathogen that is mainly involved in nosocomial infection. The aim of this study was to analyze the antimicrobial susceptibilities and clinical characterization of P. aeruginosa isolates from urinary tract infections (UTIs).

MATERIALS AND METHODS

The study collected all P. aeruginosa UTI strains from a hospital in Chongqing, China, from January 1st, 2010 to December 31st, 2011. The antibiotic susceptibilities of the P. aeruginosa isolates were analyzed using the agar dilution method and the genotypes were assessed using random amplification of polymorphic DNA-PCR (RAPD-PCR). The clinical characteristics of the patients with UTIs were collected from the hospital information systems, and significance was analyzed using the proportion test.

RESULTS

A total of 2,778 episodes of culture-proven UTIs were used in the study. There were 198 infections (7.1%) caused by P. aeruginosa. P. aeruginosa strains were highly resistant to most drugs tested. The RAPD-PCR data revealed that the 198 P. aeruginosa infections had 82 different genotypes. Antibacterial use, previous UTI, urinary tract catheter and urinary tract operation were found to be risk factors for the development of UTIs.

CONCLUSIONS

P. aeruginosa is the second most common UTI pathogen in our hospital. We should closely monitor patients with risk factors for P. aeruginosa infection.

Transcriptional activation of the mrkA promoter of the Klebsiella pneumoniae type 3 fimbrial operon by the c-di-GMP-dependent MrkH protein

The Gram-negative bacterial pathogen Klebsiella pneumoniae forms biofilms to facilitate colonization of biotic and abiotic surfaces. The formation of biofilms by K. pneumoniae requires the expression of type 3 fimbriae: elongate proteinaceous filaments extruded by a chaperone-usher system in the bacterial outer membrane. The expression of the mrkABCDF cluster that encodes this fimbrial system is strongly positively regulated by MrkH, a transcriptional activator that responds to the second messenger, c-di-GMP. In this study, we analyzed the mechanism by which the MrkH protein activates transcriptional initiation from the mrkA promoter. A mutational analysis supported by electrophoretic mobility shift assays demonstrated that a 12-bp palindromic sequence (the MrkH box) centered at -78.5 is the binding site of MrkH. Deletion of half a turn, but not a full turn, of DNA located between the MrkH box and the mrkA promoter destroyed the ability of MrkH to activate mrkA transcription. In addition, a 10-bp AT-rich sequence (the UP element) centered at -63.5 contributed significantly to MrkH-dependent mrkA transcription. In vivo analysis of rpoA mutants showed that the R265 and E273 determinants in the C-terminal domain of RNA polymerase α subunit are needed for MrkH-mediated activation of mrkA transcription. Furthermore, results from mutagenesis of the mrkH gene suggest that the N-terminal region of the protein is involved in transcriptional activation. Taken together, our results suggest that MrkH activates mrkA expression by interacting directly with RNA polymerase, to overcome the inefficient transcriptional initiation caused by the presence of defective core promoter elements.

In vitro activity of ceftolozane-tazobactam against Pseudomonas aeruginosa isolates obtained from patients in Canadian hospitals in the CANWARD study, 2007 to 2012

The in vitro activity of ceftolozane in combination with tazobactam (fixed concentration of 4 μg/ml) was evaluated against 2,435 Pseudomonas aeruginosa clinical isolates obtained from across Canada using Clinical and Laboratory Standards Institute broth microdilution methods. The MIC50 and MIC90 values for ceftolozane-tazobactam were 0.5 μg/ml and 1 μg/ml, respectively (a 32-fold-lower MIC90 than that for ceftazidime). Eighty-nine percent (141/158) of multidrug-resistant isolates were inhibited by ≤8 μg/ml of ceftolozane-tazobactam.

Antibiotic Resistance of Uropathogens Isolated from Al-Shifa Hospital in Gaza Strip in 2002

A survey on clinical isolates from urine samples was conducted and the data obtained were analyzed to determine the most common bacterial causes of urinary tract infection in the Gaza Strip and to evaluate the sensitivity patterns to selected antimicrobials that are commonly used to treat such pathogens. Urine samples were taken for culture from inpatients and outpatients at Al-shifa hospital in Gaza. Urinary tract pathogens were identified and their susceptibility to antimicrobials was determined. Of the 4778 processed urine samples, only 1637 were recorded as positive (34%) and only 1283 were tested for antimicrobial susceptibility. Escherichia coli was the most frequent uropathogen (42%), followed by Klebsiella spp. (12.2%), Pseudomonas spp. < (10.2%), other Gram-negative bacilli (8%), b hemolytic streptococci (7.6%), Enterococcus spp. (6.9%), other Staphylococcus spp. (including S . saprophyticus) (6.5%), Proteus (4.5%), S. aureus (2.1%). Resistance to antimicrobials was extremely alarming. E. coli resistance to amoxicillin reached 97.9%, to piperacillin 78.3%, to doxycycline 90%, to sulfamethoxazole/trimethoprim 63.9% and to cefaclor 42.2%.

Innate immune responses to Proteus mirabilis flagellin in the urinary tract

Flagella are bacterial virulence factors allowing microorganisms to move over surfaces. Flagellin, the structural component of flagella, is sensed by the host via Toll and NOD-like receptors and triggers pro-inflammatory responses. The use of Toll-like receptors agonists to modulate innate immune responses has aroused great interest as an alternative to improve the treatment of diverse infectious diseases. Proteus mirabilis is a Gram negative bacterium that causes urinary tract infections in humans. In the present work we used different approaches to study the ability of P. mirabilis flagellin to induce an innate immune response. We demonstrated that P. mirabilis flagellin has the ability to induce pro-inflammatory chemokines expression in T24 bladder cultures cells and in the mouse bladder after instillation. It was evidenced also that flagellin from different P. mirabilis strains differed in their capacity to induce an innate immune response in the CacoCCL20-Luc system. Also, flagellin elicited inflammation, with recruitment of leukocytes to the bladder epithelium. Flagellin instillation before an experimental P. mirabilis infection showed that the inflammatory response due to flagellin did not help to clear the infection but favored bacterial colonization. Thus, induction of inflammatory response in the bladder did not contribute to P. mirabilis infection neutralization.

Nationwide surveillance of antimicrobial susceptibility patterns of pathogens isolated from surgical site infections (SSI) in Japan

To investigate the trends of antimicrobial resistance in pathogens isolated from surgical site infections (SSI), a Japanese surveillance committee conducted the first nationwide survey. Seven main organisms were collected from SSI at 27 medical centers in 2010 and were shipped to a central laboratory for antimicrobial susceptibility testing. A total of 702 isolates from 586 patients with SSI were included. Staphylococcus aureus (20.4 %) and Enterococcus faecalis (19.5 %) were the most common isolates, followed by Pseudomonas aeruginosa (15.4 %) and Bacteroides fragilis group (15.4 %). Methicillin-resistant S. aureus among S. aureus was 72.0 %. Vancomycin MIC 2 μg/ml strains accounted for 9.7 %. In Escherichia coli, 11 of 95 strains produced extended-spectrum β-lactamase (Klebsiella pneumoniae, 0/53 strains). Of E. coli strains, 8.4 % were resistant to ceftazidime (CAZ) and 26.3 % to ciprofloxacin (CPFX). No P. aeruginosa strains produced metallo-β-lactamase. In P. aeruginosa, the resistance rates were 7.4 % to tazobactam/piperacillin (TAZ/PIPC), 10.2 % to imipenem (IPM), 2.8 % to meropenem, cefepime, and CPFX, and 0 % to gentamicin. In the B. fragilis group, the rates were 28.6 % to clindamycin, 5.7 % to cefmetazole, 2.9 % to TAZ/PIPC and IPM, and 0 % to metronidazole (Bacteroides thetaiotaomicron; 59.1, 36.4, 0, 0, 0 %). MIC₉₀ of P. aeruginosa isolated 15 days or later after surgery rose in TAZ/PIPC, CAZ, IPM, and CPFX. In patients with American Society of Anesthesiologists (ASA) score ≥3, the resistance rates of P. aeruginosa to TAZ/PIPC and CAZ were higher than in patients with ASA ≤2. The data obtained in this study revealed the trend of the spread of resistance among common species that cause SSI. Timing of isolation from surgery and the patient's physical status affected the selection of resistant organisms.

Antimicrobial susceptibility of Enterobacteriaceae, including molecular characterization of extended-spectrum beta-lactamase-producing species, in urinary tract isolates from hospitalized patients in North America and Europe: results from the SMART study 2009-2010

In 2009-2010, 3646 urinary tract isolates of Enterobacteriaceae spp. were isolated from hospitalized patients in North America and Europe. Extended-spectrum beta-lactamase (ESBL) production was detected in 8.5% and 8.8% of Escherichia coli and Klebsiella pneumoniae, respectively, in North America and in 17.6% and 38.9% for Europe, respectively. The carbapenems (ertapenem and imipenem) were the most active agents in vitro, with ampicillin-sulbactam the least active. Molecular characterization of about 50% of ESBL-positive isolates identified the presence of bla(CTX-M) genes in over 90% of Escherichia coli from both continents. bla(KPC) was more common in North American isolates of K. pneumoniae than in European isolates (21.4% versus 6.9%). bla(TEM) and AmpC genes were infrequent. Enterobacteriaceae spp. isolated from hospitalized patients with urinary tract infections in both North America and Europe are often resistant to commonly used antimicrobials with bla(CTX-M) genes common in both Escherichia coli and K. pneumoniae.

Antimicrobial susceptibility of Pseudomonas aeruginosa isolates obtained from patients in Canadian hospitals: CANWARD 2008-2011

Broth microdilution (Clinical and Laboratory Standards Institute) was used to evaluate the antimicrobial susceptibility of 1549 Pseudomonas aeruginosa clinical isolates collected in Canada between January 2008 and October 2011. The percentage of isolates susceptible was as follows: amikacin 92.0%, ceftazidime 83.5%, ciprofloxacin 74.3%, colistin 93.4%, gentamicin 76.8%, meropenem 82.7%, and piperacillin-tazobactam 83.6%. Antimicrobial susceptibility did not change significantly between 2008 and 2011, with the exception of increasing susceptibility to gentamicin (P < 0.0001).

Change in antimicrobial susceptibility of Escherichia coli urinary tract isolates at a single institution over a period of 10 years

Urinary tract infections are common. Few published studies have demonstrated the change in Escherichia coli urinary isolate antimicrobial susceptibility over time within a given area and (or) population. The purpose of this study was to evaluate the change in susceptibility of E. coli clinical isolates obtained from urine specimens at a single institution over a period of 10 years. The microbiology laboratory information system at St. Boniface Hospital (Winnipeg, Manitoba, Canada) was searched retrospectively from 1 January 2000 to 31 December 2009, for all E. coli isolates from either a midstream or catheter urine source that had susceptibility testing performed. Only one isolate per patient was included during the entire study period. Antimicrobial susceptibility testing was carried out with either a Microscan instrument (pre-April 2004) or a Vitek instrument (May 2004 onwards). In total, 7353 E. coli urinary isolates were included for evaluation. Ciprofloxacin susceptibility declined significantly, from 99% in 2000 to 85% in 2009 (p < 0.0001). A small but statistically significant decline in susceptibility was also observed for ampicillin, cefazolin, trimethoprim-sulfamethoxazole, gentamicin, and nitrofurantoin. These data suggest that certain antimicrobials recommended for the treatment of urinary tract infections (ciprofloxacin, trimethoprim-sulfamethoxazole) may no longer be optimal.

Temporal interplay between efflux pumps and target mutations in development of antibiotic resistance in Escherichia coli

The emergence of resistance presents a debilitating change in the management of infectious diseases. Currently, the temporal relationship and interplay between various mechanisms of drug resistance are not well understood. A thorough understanding of the resistance development process is needed to facilitate rational design of countermeasure strategies. Using an in vitro hollow-fiber infection model that simulates human drug treatment, we examined the appearance of efflux pump (acrAB) overexpression and target topoisomerase gene (gyrA and parC) mutations over time in the emergence of quinolone resistance in Escherichia coli. Drug-resistant isolates recovered early (24 h) had 2- to 8-fold elevation in the MIC due to acrAB overexpression, but no point mutations were noted. In contrast, high-level (≥ 64× MIC) resistant isolates with target site mutations (gyrA S83L with or without parC E84K) were selected more readily after 120 h, and regression of acrAB overexpression was observed at 240 h. Using a similar dosing selection pressure, the emergence of levofloxacin resistance was delayed in a strain with acrAB deleted compared to the isogenic parent. The role of efflux pumps in bacterial resistance development may have been underappreciated. Our data revealed the interplay between two mechanisms of quinolone resistance and provided a new mechanistic framework in the development of high-level resistance. Early low-level levofloxacin resistance conferred by acrAB overexpression preceded and facilitated high-level resistance development mediated by target site mutation(s). If this interpretation is correct, then these findings represent a paradigm shift in the way quinolone resistance is thought to develop.

Antimicrobial susceptibility of global inpatient urinary tract isolates of Escherichia coli: results from the Study for Monitoring Antimicrobial Resistance Trends (SMART) program: 2009-2010

Escherichia coli is the most important uropathogen. The Study for Monitoring Antimicrobial Resistance Trends program collected 1643 E. coli isolates in 2009-2010 from urinary tract infection (UTI) specimens of hospitalized patients in countries worldwide. Ertapenem and imipenem were the most active agents tested, inhibiting >98% of all E. coli phenotypes. Overall, 17.9% of isolates were extended-spectrum beta-lactamase (ESBL) producers. The highest ESBL rate was from the Asia/Pacific region (27.7%). Amikacin and piperacillin-tazobactam achieved 90% inhibition levels only for ESBL-negative isolates. Ciprofloxacin and levofloxacin were not effective for ESBL-positive isolates, with only 14.6% and 15.9% susceptible, respectively. These observations highlight the need for continued monitoring of susceptibility of E. coli isolated from hospitalized patients with UTIs.

Antimicrobials in urogenital infections

Urinary tract infections (UTIs) and male genital infections are amongst the most prevalent infections. A prudent antibiotic policy therefore has a large impact on society. The clinical classification in uncomplicated cystitis, uncomplicated pyelonephritis, complicated UTI and genital infections is useful, also for the right choice of antibiotic treatment. In this regard pharmacokinetic and pharmacodynamic aspects have to be considered. Nowadays in uncomplicated cystitis antibiotics exclusively reserved for this indication are preferred, such as fosfomycin trometamol, nitrofurantoin and pivmecillinam, in order to reduce antibiotic pressure in this extremely frequent entity. In complicated UTI a broad bacterial spectrum has to be considered. Different antibiotic substances should be used for treatment, such as penicillins, with β-lactamase inhibitors, cephalosporins or carbapenems, fluoroquinolones, aminoglycosides or cotrimoxazole, if tested susceptible. For genital infections the pharmacokinetic properties of the antibiotics should especially be considered, such as in prostatitis, where mainly fluoroquinolones and macrolides show sufficient pharmacokinetic parameters for treatment of bacterial infections. Furthermore in genital infections fastidious organisms, such as Chlamydia or Mycoplasma spp. have to be considered with respect to their antimicrobial susceptibility.

Demographic features and antibiotic resistance among children hospitalized for urinary tract infection in northwest Iran

Introduction:

Urinary tract infection (UTI) is the most common serious bacterial infection during infancy. The aim of the present study was to evaluate demographic characteristics, clinical presentations and findings, and antimicrobial resistance among infants and children hospitalized in Tabriz Children’s Hospital, Tabriz, Iran.

Methods:

In this descriptive observational study, 100 children who had been admitted with UTI diagnosis to Tabriz Children’s Hospital from March 2003 to March 2008 were studied. Demographic characteristics, chief complaints, clinical presentations and findings, urine analysis and cultures, antimicrobial resistance, and sonographic and voiding cystourethrographic reports were evaluated.

Results:

The mean age of patients was 35.77 ± 39.86 months. The male to female ratio was 0.26. The mean white blood cell count was 12,900 ± 5226/mm³. Sixty-two percent of patients had leukocytosis. The most common isolated pathogen was Escherichia coli spp (77%) followed by Klebsiella spp (10%), Enterobacter spp (9%), and Enterococcus spp (4%). Isolated pathogens were highly resistant to ampicillin, cotrimoxazole, and cephalexin (71%–96%), intermediate sensitivity to third-generation cephalosporins, and highly sensitive to ciprofloxacin (84.4%), amikacin (83.8%), and nitrofurantoin (82.8%).

Conclusion:

The most common pathogen of UTI in the hospitalized children was E. coli spp. The isolated pathogens were extremely resistant to ampicillin, and highly sensitive to ciprofloxacin and amikacin.