Urinary tract infections in general practice patients: diagnostic tests versus bacteriological culture

Adherence to and usefulness of the national treatment guideline for urinary tract infections (UTI) in a risk area

Background

To optimize antibiotic treatment and decrease antibiotic resistance, national treatment guidelines are available for urinary tract infections (UTIs) in general practice. The usefulness of these guidelines in risk areas for antimicrobial resistance such as cross border regions or areas with dense agriculture, is unknown.

Methods

Midstream urine samples from women with symptoms of acute UTI visiting general practitioners (GPs) in the Westland area, a dense agriculture area, were microbiologically analysed, and patient characteristics, symptoms, previous and present antibiotic treatment were collected. The National Nivel data were used as reference for antibiotic resistance.

Results

Of 310 women with symptoms of uncomplicated UTI, 247 (80%) had a culture proven E. coli UTI. Empirical antibiotic therapy was prescribed to 148 patients (48%) in total; in 7% of women with a negative and 52% with a positive urine culture. Having more than one symptom was associated with the prescription of antibiotics; travel history or previous antibiotic use for UTI were not. The isolated uropathogens were susceptible to the empiric antibiotic therapy in 98% of patients. Resistance to co-amoxiclav was higher (22%) than reported in the national data of 2004 (12%), 2009 (13%) and 2014 (9%), as was the prevalence of extended spectrum β-lactamase (ESBL): 3.4% in our study versus 0.1%, 1% and 2.2% in the national data respectively.

Conclusion

The presence of environmental and socio-demographic risk factors for antibiotic resistance did not influence the empiric choice nor susceptibility for antibiotics advised by the national guidelines in women with uncomplicated UTI.

Trends, seasonality and the association between outpatient antibiotic use and antimicrobial resistance among urinary bacteria in the Netherlands

OBJECTIVES

To determine trends, seasonality and the association between community antibiotic use and antimicrobial resistance (AMR) in Escherichia coli and Klebsiella pneumoniae in urinary tract infections.

METHODS

We analysed Dutch national databases from January 2008 to December 2016 regarding antibiotic use and AMR for nitrofurantoin, trimethoprim, fosfomycin and ciprofloxacin. Antibiotic use was expressed as DDD/1000 inhabitant-days (DID) and AMR was expressed as the percentage of resistance from total tested isolates. Temporal trends and seasonality were analysed with autoregressive integrated moving average (ARIMA) models. Each antibiotic use-resistance combination was cross-correlated with a linear regression of the ARIMA residuals.

RESULTS

The trends of DID increased for ciprofloxacin, fosfomycin and nitrofurantoin, but decreased for trimethoprim. Similar trends were found in E. coli and K. pneumoniae resistance to the same antibiotics, except for K. pneumoniae resistance to ciprofloxacin, which decreased. Resistance levels peaked in winter/spring, whereas antibiotic use peaked in summer/autumn. In univariate analysis, the strongest and most significant cross-correlations were approximately 0.20, and had a time delay of 3-6 months between changes in antibiotic use and changes in resistance. In multivariate analysis, significant effects of nitrofurantoin use and ciprofloxacin use on resistance to these antibiotics were found in E. coli and K. pneumoniae, respectively. There was a significant association of nitrofurantoin use with trimethoprim resistance in K. pneumoniae after adjusting for trimethoprim use.

CONCLUSIONS

We found a relatively low use of antibiotics and resistance levels over a 9 year period. Although the correlations were weak, variations in antibiotic use for these four antibiotics were associated with subsequent variations in AMR in urinary pathogens.

Influence of gender on the performance of urine dipstick and automated urinalysis in the diagnosis of urinary tract infections at the emergency department

BACKGROUND

Urinary tract infections (UTIs) are frequently encountered at the Emergency Department (ED). Given the anatomical differences between men and women, we aimed to clarify differences in the diagnostic performance of urinary parameters at the ED.

METHODS

A cohort study of adults presenting at the ED with fever and/or clinical suspected UTI. Performance of urine dipstick (UD) and automated urinalysis (UF-1000i) were analysed for the total study population and men and women separately. We focused on 1) UTI diagnosis and 2) positive urine culture (UC, ≥10⁵ CFU/ml) as outcome.

RESULTS

In 360 of 917 cases (39.3%) UTI was established (men/women 35.1%/43.6%). Diagnostic accuracy of UD was around 10% lower in women compared to men. Median automated leucocyte and bacterial count were higher in women compared to men. Diagnostic performance by receiver operating analysis was 0.851 for leucocytes (men/women 0.879/0.817) and 0.850 for bacteria (men/women 0.898/0.791). At 90% sensitivity, cut-off values of leucocyte count (men 60/µL, women 43/µL), and bacterial count (men 75/µL, women 139/µL) showed performance differences in favour of men. In both men and women, diagnostic performance using specified cut-off values was not different between normal and non-normal bladder evacuation. UC was positive in 327 cases (men/women 149/178), as with UTI diagnosis, diagnostic values in men outperformed women.

CONCLUSIONS

Overall diagnostic accuracy of urinary parameters for diagnosing UTI is higher in men. The described differences in cut-off values for leukocyte and bacterial counts for diagnosing UTI necessitates gender-specific cut-off values, probably reflecting the influence of anatomical and urogenital differences.

A novel near-infrared fluorescent sensor for zero background nitrite detection via the "covalent-assembly" principle

Different chemical states of nitrogen are present in many freshwater and marine ecosystems, and nitrite ions are one of the most toxic water-soluble nitrogen species. Developing an effective and convenient sensing method to constantly detect the concentration of nitrite has become a wide concern. Here, a novel near-infrared fluorescent probe (AAC) was designed and synthesized via the "covalent assembly" principle, showing excellent selectivity and high sensitivity for nitrite. A new nitrite-quantitative method was established with the help of AAC, and the detection limit of nitrite using the new method was as low as 6.7 nM. AAC was successfully applied for the quantitative detection of nitrite in real-world environmental and food samples (including river water and Chinese sauerkraut), and the detection results were essentially identical to the results obtained from the traditional Griess assay. Moreover, AAC was successfully applied for tracking nitrite in Escherichia coli by fluorescence imaging. Since nitrite can have devastating effects, the method established with AAC allowed us to "see" effectively about the water quality, food quality, etc.

Plasticity of Coagulase-Negative Staphylococcal Membrane Fatty Acid Composition and Implications for Responses to Antimicrobial Agents

Staphylococcus aureus demonstrates considerable membrane lipid plasticity in response to different growth environments, which is of potential relevance to response and resistance to various antimicrobial agents. This information is not available for various species of coagulase-negative staphylococci, which are common skin inhabitants, can be significant human pathogens, and are resistant to multiple antibiotics. We determined the total fatty acid compositions of Staphylococcus auricularis, Staphylococcus capitis, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus hominis, Staphylococcus saprophyticus, and Staphylococcus aureus for comparison purposes. Different proportions of branched-chain and straight-chain fatty acids were observed amongst the different species. However, growth in cation-supplemented Mueller-Hinton broth significantly increased the proportion of branched-chain fatty acids, and membrane fluidities as measured by fluorescence anisotropy. Cation-supplemented Mueller-Hinton broth is used for routine determination of antimicrobial susceptibilities. Growth in serum led to significant increases in straight-chain unsaturated fatty acids in the total fatty acid profiles, and decreases in branched-chain fatty acids. This indicates preformed fatty acids can replace biosynthesized fatty acids in the glycerolipids of coagulase-negative staphylococci, and indicates that bacterial fatty acid biosynthesis system II may not be a good target for antimicrobial agents in these organisms. Even though the different species are expected to be exposed to skin antimicrobial fatty acids, they were susceptible to the major skin antimicrobial fatty acid sapienic acid (C16:1Δ6). Certain species were not susceptible to linoleic acid (C18:2Δ9,12), but no obvious relationship to fatty acid composition could be discerned.

Antibiotic resistance of Escherichia coli isolated from uncomplicated UTI in general practice patients over a 10-year period

Recommendations of first choice antibiotic therapy need to be based on actual antibiotic susceptibility data. We determined the antibiotic susceptibility of E. coli in uncomplicated UTI among women and compared the results with 2004 and 2009. In 30 sentinel general practitioner practices of Nivel Primary Care database, urine samples were collected from women with symptoms of uncomplicated UTI. Patient characteristics, E. coli susceptibility, and ESBL production were analyzed. Six hundred eighty-nine urine samples were collected; E. coli was the most isolated uropathogen (83%). Antibiotic susceptibility was stable over time except for ciprofloxacin (96% in 2004, 97% in 2009, and 94% in 2014; P < 0.05). The susceptibility to co-amoxiclav was 88%, 87%, and 92% in 2004, 2009, and 2014, respectively. The prevalence of ESBL-producing E. coli increased from 0.1% in 2004 to 2.2% in 2014 (P < 0.05). Regional differences in antibiotic susceptibility for co-trimoxazole were found being the highest in the west (88%) and the lowest in the north (72%, P = 0.021). Ciprofloxacin susceptibility was related to antibiotic use in the past 3 months (97% no use versus 90% use, P = 0.002) and age > 70 years (P = 0.005). In 2014, prescription of fosfomycin increased compared to 2009 (14.3% versus 5.6%) at the expense of co-amoxiclav, co-trimoxazole, and fluoroquinolones (P < 0.05). The susceptibility percentages to most antimicrobial agents tested were stable over 10 years’ period although the prevalence of E. coli and ESBLs significantly increased. Performance of a survey with regular intervals is warranted.

Rapid time-resolved luminescence based screening of bacteria in urine with luminescence modulating biosensing phages

Urinary tract infections (UTIs) are a common problem worldwide. The most prevalent causative pathogen of UTI is Escherichia coli, focus of this study. The current golden standard for detecting UTI is bacterial culture, creating a major workload for hospital laboratories - cost-effective and rapid mass screening of patient samples is needed. Here we present an alternative approach to screen patient samples with a single-step assay utilising time-resolved luminescence and luminescence modulating biosensing phages. Filamentous phage M13 was biopanned for binding luminescence quenching metal (copper) and further E. coli. The screening assay luminescence modulation was further enhanced by selecting right chemical environment for the functioning phage clones. Semi-specific interaction between phage, target bacteria and metal was detected by modulation in the signal of a weakly chelating, easily quenchable lanthanide complex. In the presence of the target pathogen, the phages collected quenching metal from solution to the bacterial surface changing the quenching effect on the lanthanide label and thus modulating the signal. Our method was compared with the bacterial culture data obtained from 70 patient samples. The developed proof-of-principle screening assay showed sensitivity and a specificity at the 90% mark when compared to culture method although some samples had high turbidity and even blood. The detection limit of E. coli was in the range of 1000-10 000 colony forming units/mL. Untreated urine sample was screened and time-resolved luminescence signal result was achieved within 10 min in a single incubation step.

Uncomplicated urinary tract infections in Swedish primary care; etiology, resistance and treatment

Background

Uncomplicated urinary tract infection (uUTI) is common and a majority of patients are prescribed antibiotics. There is little knowledge about antibiotic resistance in urine samples from patients with uUTI in primary health care (PHC).

The aim was to describe antibiotic treatment, bacterial findings, the prevalence of resistant E.coli and factors associated with antibiotic resistance. The aim was also to compare the prevalence of resistant E.coli in clinical practice with the prevalence of resistant E.coli in routine microbiological laboratory data.

Methods

This observational study in PHC setting started in November 2014 and ended in March 2016. Women aged 17 years and older with symptoms indicating uUTI from eight PHCs were included. Questionnaires were used to retrieve anamnestic data. All urine samples were sent to the local laboratory of microbiology for diagnostic analysis and susceptibility testing. Proportions of resistant E.coli were compared with corresponding data from the regional laboratory.

Results

Urine cultures were analysed in 304 women with a median age of 46 (IQR 32–66) years. Bacterial growth was found in 243 (80%) of urine samples, and E.coli in 72% of the positive samples. A total of 80% of detected E.coli isolates were susceptible to all tested antimicrobials and resistance rates to ciprofloxacin were lower than reported from the local clinical laboratory. Antibiotic treatment within the last year was independently associated with antibiotic resistant E.coli in the urine sample adjusted OR 4.97 (95% CI 2.04–12.06). A total of 74% of the women were treated with antibiotics. The most prescribed was pivmecillinam followed by nitrofurantoin.

Conclusions

Antibiotic resistance in E.coli was low. Antibiotic treatment within the last year was associated with antibiotic resistant E.coli. Data from the clinical microbiology laboratory indicates that laboratory data may overestimate antibiotic resistance and lead to an unnecessary change in empiric antibiotic treatment of uUTI in primary care. The empirically prescribed antibiotics, were inline with Swedish treatment recommendations for uUTI.

Zoonotic multidrug-resistant microorganisms among small companion animals in Germany

Antimicrobial multidrug-resistant microorganisms (MDRO) can be transmitted between companion animals and their human owners. Aim of this study was to determine the prevalence of extended spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) and Staphylococcus aureus including methicillin-resistant S. aureus (MRSA) in different companion animal species. Dogs (n = 192), cats (n = 74), and rabbits (n = 17), treated in a veterinary practice and hospital or living in an animal shelter and private households, were sampled. All facilities were located in a region characterized by a high density of pig production. Nasal, buccal and perianal swabs were enriched and cultured on solid chromogenic selective media. A subgroup of 20 animals (13 dogs, 3 cats, 4 rabbits) was analyzed for the presence of staphylococci other than S. aureus. Amongst all animals (n = 283), twenty dogs (10.4%) and six cats (8.1%) carried S. aureus. MRSA was found in five dogs (2.6%) and two cats (2.7%). Isolates were of spa types t011, t034, t108 (all mecA-positive, ST398), and t843 (mecC-positive, ST130), typical for livestock-associated (LA)-MRSA. Except for one dog, MRSA-positive animals did not have direct contact to husbandry. ESBL-Escherichia coli (bla_CTX-M/bla_TEM/bla_SHV genes) were present in seven dogs (3.6%), one cat (1.4%) possessed a cefotaxime-resistant Citrobacter freundii isolate (bla_TEM/bla_CMY-2 genes). MDRO carriage was associated with animals from veterinary medical settings (p<0.05). One dog and one rabbit carried methicillin-resistant coagulase-negative staphylococci. The exclusive occurrence of MRSA lineages typically described for livestock stresses the impact of MDRO strain dissemination across species barriers in regional settings. Presence of ESBL-E and LA-MRSA among pets and probable dissemination in clinical settings support the necessity of a “One Health” approach to address the potential threats due to MDRO-carrying companion animals.

Utility of initial procalcitonin values to predict urinary tract infection

BACKGROUND

Urinary tract infections (UTIs) are one of the most common reasons women seek treatment in the emergency department (ED). The biomarker procalcitonin (PCT) has gained popularity over the last decade to improve the diagnosis of bacterial infections and reduce unnecessary exposure to antibiotics. PCT has been extensively studied in patients with pneumonia and sepsis and may have additional role in UTI.

METHODS

A retrospective study of patients who presented to the ED in which a urinalysis test and a PCT level was obtained within the first 24h of presentation. Signs and symptoms of UTI and urine cultures were reviewed to determine a positive diagnosis of UTI. The area under the receiver operating curve was used to calculate the test characteristics of PCT. Different breakpoints were analyzed to determine which PCT level corresponded to the highest sensitivity and specificity.

RESULTS

293 patients were included in this single center, retrospective study. The AUC of PCT to predict UTI was 0.717; 95% CI: 0.643-0.791 (p<0.001). A PCT threshold of 0.25ng/ml corresponded to the best combination of sensitivity (67%) and specificity (63%), with a positive predictive value and negative predictive value of 26% and 91%, respectively.

CONCLUSIONS

A PCT threshold <0.25ng/ml was a strong predictor of the absence of UTI. The high negative predictive value of PCT may be useful as an adjunct to urinalysis results to rule out UTI and facilitate noninitiation or earlier discontinuation of empiric antibiotics.

New markers of urinary tract infection

Urinary tract infection (UTI) is the most common bacterial infection independent of age. It is also one of the most common causes of hospitalizations for infections among elderly people and the most common indication for antibiotic prescriptions in primary care. Both diagnostics and management of lower and upper urinary tract infections provide challenges in clinical practice due to their high prevalence and recurrence, and worldwide increase of antibiotic resistance. The clinical symptoms of UTI are often uncharacteristic or asymptomatic. The accurate diagnosis and early treatment are crucial due to risk of septicaemia and long-term consequences. Currently the diagnosis of urinary tract infection is based on the presence of clinical symptoms in combination with the results of nitrite strip test indicating the presence of bacteria in urine and semi-quantitative measurement of white blood cells count in urine. Although urine culture is the gold standard in UTI diagnostics it is both time-consuming and costly. Searching for novel biomarkers of UTI has attracted much attention in recent years. The article reviews several promising serum and urine biomarkers of UTI such as leukocyte esterase, C-reactive protein, procalcitonin, interleukins, elastase alpha (1)-proteinase inhibitor, lactofferin, secretory immunoglobulin A, heparin-binding protein, xanthine oxidase, myeloperoxidase, soluble triggering receptor expressed on myeloid cells-1, α-1 microglobulin (α1Mg) and tetrazolium nitroblue test (TNB).

Inadequate adherence to Swedish guidelines for uncomplicated lower urinary tract infections among adults in general practice

In a primary care study of urinary tract infections (UTIs) performed 2008 in Uppsala County, Sweden, 43% of the patients were culture negative. In order to investigate the background to the observed overdiagnosis of UTI, study invitations were sent to the previously included patients. A total of 256 patients (88% women) approved to participate. Patient charts and recorded laboratory data were reviewed. Two or more of the cardinal symptoms were reported in 53% of the women and in 19% of the men. A dipstick test was performed in 93% of the consultations. The highest positive predicted values in women had a positive nitrite test (95%, 95% CI 87; 99) and dysuria in combination with urgency (81%, 95% CI 72; 88). Seventy-one percent of the women who fulfilled the symptom criteria received an antibiotic prescription directly, 87% of these had a positive culture. The drug of choice was pivmecillinam for women (51%) and quinolones (50%) for men. The treatment duration was too long for the women; 68% were treated for ≥7 days. In conclusion, the adherence to national guidelines/recommendations was inadequate. To reduce the selection of multiresistant bacteria, an improvement of the use of diagnostic criteria/tools and antibiotic drugs in primary care is necessary.

Point-Counterpoint: Reflex Cultures Reduce Laboratory Workload and Improve Antimicrobial Stewardship in Patients Suspected of Having Urinary Tract Infections

Urinary tract infections (UTIs) are frequent and lead to a large number of clinical encounters. A common management strategy for patients suspected of having a urinary tract infection is to test for pyuria and bacteria by urine analysis (UA) of midstream urine, with initiation of antibiotic therapy and urine culture if one or both tests are positive. Although this practice was first used in an outpatient setting with midstream urine samples, some institutions allow its use in the management of catheterized patients. The ideas behind the reflex urine culture are to limit laboratory workload by not performing culture on negative specimens and to improve antimicrobial stewardship by not giving antimicrobials to patients with negative UA results. The questions are, first, whether reflex urine culture reduces workloads significantly and, second, whether it improves antimicrobial stewardship in the era of increasing numbers of urinary tract infections due to extensively drug-resistant Gram-negative bacilli. Romney Humphries from UCLA supports the idea that reflex urine cultures are of value and describes what reflex parameters are most useful, while Jennifer Dien Bard of Children's Hospital Los Angeles discusses their limitations.

High Diagnostic Accuracy of Nitrite Test Paired with Urine Sediment can Reduce Unnecessary Antibiotic Therapy

BACKGROUND

Urinary tract infections (UTIs) are common bacterial infections dominated by lower UTI in women (LUTIW). Symptoms only are insufficient for diagnosis and accordingly, near patient diagnostic tests confidently confirming significant bacteriuria are desirable. The nitrite test (NIT) has low sensitivity, while bacterial and leukocyte counts disjunctively paired in urine sediment microscopy (SED) have high sensitivity. Similar symptomatic cure rates are found post antibiotic vs. placebo therapy in patients with negative cultures. Consequently, prescription on symptoms only implies unnecessary antibiotic therapy.

AIMS

to evaluate the diagnostic outcomes of NIT, SED and NIT disjunctively paired with SED (NIT+SED) vs. urine culture, with special focus on bladder incubation time (BIT), and to assess if NIT+SED can reduce unnecessary antibiotic therapy.

METHODS

A diagnostic, primary care, multicentre study including 1070 women with symptoms suggestive of lower UTI.

RESULTS

Significant bacteriuria was found in 77%. The BIT highly influenced the diagnostic outcomes and the optimal duration was ≥4h with sensitivity of 66, 90 and 95% for NIT, SED and NIT+SED, respectively. SED performed only in NIT negative specimens could reduce unnecessary antibiotics by 10% vs. prescription on symptoms only. The number needed to test with SED to reduce one unnecessary antibiotic course was five patients at BIT ≥4h and six patients at ≤3h or overall.

CONCLUSION

The BIT highly influences the diagnostic outcomes with the highest accuracy of NIT+SED. Diagnosis of LUTIW with NIT+SED can reduce unnecessary antibiotic therapy and subsequently decrease antimicrobial resistance.

TRIAL REGISTRATION

The Swedish Medical Product Agency 1995 03 01:151:01783/94.

Nitrite ion-induced fluorescence quenching of luminescent BSA-Au(25) nanoclusters: mechanism and application

Fluorescence quenching is an interesting phenomenon which is highly useful in developing fluorescence based sensors. A thorough understanding of the fluorescence quenching mechanism is essential to develop efficient sensors. In this work, we investigate different aspects governing the nitrite ion-induced fluorescence quenching of luminescent bovine serum albumin stabilized gold nanoclusters (BSA-Au NCs) and their application for detection of nitrite in urine. The probable events leading to photoluminescence (PL) quenching by nitrite ions were discussed on the basis of the results obtained from ultraviolet-visible (UV-Vis) absorption spectroscopy, X-ray photoelectron spectroscopy (XPS), fluorescence measurements, circular dichroism (CD) spectroscopy, zeta potential and dynamic light scattering (DLS) studies. These studies suggested that PL quenching mainly occurred through the oxidation of Au(0) atoms to Au(i) atoms in the core of BSA-Au NCs mediated by nitrite ions. The interference caused by certain species such as Hg(2+), Cu(2+), CN(-), S(2-), glutathione, cysteine, etc. during the nitrite determination by fluorescence quenching was eliminated by using masking agents and optimising the conditions. Based on these findings we proposed a BSA-Au NC-modified membrane based sensor which would be more convenient for the real life applications such as nitrite detection in urine samples. The BSA-Au NC-modified nitrocellulose membrane (NCM) enabled the detection of nitrite at a level as low as 100 nM in aqueous solutions. This Au NC-based paper probe was validated to exhibit good performance for nitrite analysis in environmental water and urine samples, which makes it useful in practical applications.

Reliability of dipstick assay in predicting urinary tract infection

Aims:

Urine dipstick analysis is a quick, cheap and a useful test in predicting Urinary Tract Infection (UTI) in hospitalized patients. Our aim is to evaluate the reliability (sensitivity) of urine dipstick analysis against urine culture in the diagnosis of UTI.

Materials and Methods:

Patients admitted to our hospital suspected of having UTI, with positive urine cultures were included in this study from a 2-year period (January 2011 to December 2012). Dipstick urinalysis was done using multistix 10 SG (Siemens) and clinitek advantus analyzer. The sensitivity of dipstick nitrites, leukocyte esterase and blood in these culture-positive UTI patients was calculated retrospectively.

Results:

Urine dipstick analysis of 635 urine culture-positive patients was studied. The sensitivity of nitrite alone and leukocyte esterase alone were 23.31% and 48.5%, respectively. The sensitivity of blood alone in positive urine culture was 63.94%, which was the highest sensitivity for a single screening test. The presence of leukocyte esterase and/or blood increased the sensitivity to 72.28%. The sensitivity was found to be the highest when nitrite, leukocyte and blood were considered together.

Conclusions:

Nitrite test and leukocyte esterase test when used individually is not reliable to rule out UTI. Hence, symptomatic UTI patients with negative dipstick assay should be subjected to urine culture for a proper management.

Flow cytometry analysis using sysmex UF-1000i classifies uropathogens based on bacterial, leukocyte, and erythrocyte counts in urine specimens among patients with urinary tract infections

Urinary tract infections (UTIs) are the second most common bacterial infection. Urine culture is the gold standard for diagnosis, but new techniques, such as flow cytometry analysis (FCA), have been introduced. The aim of the present study was to evaluate FCA characteristics regarding bacteriuria, leukocyturia, and erythrocyturia in relation to cultured uropathogens in specimens from patients with a suspected UTI. We also wanted to evaluate whether the FCA characteristics can identify uropathogens prior to culture. From a prospective study, 1,587 consecutive urine specimens underwent FCA prior to culture during January and February 2012. Outpatients and inpatients (79.6% and 19.4%, respectively) were included, of whom women represented 67.5%. In total, 620 specimens yielded growth, of which Escherichia coli represented 65%, Enterococcus spp. 8%, Klebsiella spp. 7%, and Staphylococcus spp. 5%. For the uropathogens, the outcome of FCA was compared against the results for specimens with E. coli and those with a negative culture. E. coli had high bacterial (median, 17,914/μl), leukocyte (median, 348/μl), and erythrocyte (median, 23/μl) counts. With the exception of Klebsiella spp., the majority of the uropathogens had considerable or significantly lower bacterial counts than that of E. coli. High leukocyte counts were found in specimens with Staphylococcus aureus, Proteus mirabilis, Pseudomonas aeruginosa, and group C streptococci. Elevated erythrocyte counts were found for P. vulgaris, P. aeruginosa, and group C streptococci, as well as for Staphylococcus saprophyticus. In essence, FCA adds new information about the bacterial, leukocyte, and erythrocyte counts in urine specimens for different uropathogens. Based on FCA characteristics, uropathogens can be classified and identified prior to culture. E. coli and Klebsiella spp. have similar FCA characteristics.

Coagulase-negative staphylococci

The definition of the heterogeneous group of coagulase-negative staphylococci (CoNS) is still based on diagnostic procedures that fulfill the clinical need to differentiate between Staphylococcus aureus and those staphylococci classified historically as being less or nonpathogenic. Due to patient- and procedure-related changes, CoNS now represent one of the major nosocomial pathogens, with S. epidermidis and S. haemolyticus being the most significant species. They account substantially for foreign body-related infections and infections in preterm newborns. While S. saprophyticus has been associated with acute urethritis, S. lugdunensis has a unique status, in some aspects resembling S. aureus in causing infectious endocarditis. In addition to CoNS found as food-associated saprophytes, many other CoNS species colonize the skin and mucous membranes of humans and animals and are less frequently involved in clinically manifested infections. This blurred gradation in terms of pathogenicity is reflected by species- and strain-specific virulence factors and the development of different host-defending strategies. Clearly, CoNS possess fewer virulence properties than S. aureus, with a respectively different disease spectrum. In this regard, host susceptibility is much more important. Therapeutically, CoNS are challenging due to the large proportion of methicillin-resistant strains and increasing numbers of isolates with less susceptibility to glycopeptides.

Distribution and antimicrobial susceptibility pattern of bacterial pathogens causing urinary tract infection in urban community of meerut city, India

Urinary tract infection is one of the common infections in the Indian community. Distribution and susceptibility of UTI-causing pathogens change according to time and place. This study was conducted to determine the distribution and antimicrobial susceptibility of uropathogens in the Indian community as well as to determine the effect of gender and age on the etiology of bacterial uropathogens. Clean catch midstream urine samples were collected from 288 patients of the age ranging from 15 to ≥48 years. Antimicrobial susceptibility was performed on all isolated bacteria by Kirby Bauer's disc diffusion method. The multiple antibiotic resistance (MAR) index of each antibiotic was calculated. The UTI prevalence was 53.82% in patients; however, the prevalence was significantly higher in females than in males (females: 73.57%; males: 35.14%; P = 0.000). Females within the age group of 26-36 years and elderly males of ≥48 years showed higher prevalence of UTI. Gram negative bacteria (90.32%) were found in high prevalence than Gram positive (9.68%). Escherichia coli (42.58%) was the most prevalent gram negative isolate. Nitrofurantoin (78.71%) was found the most resistant drug among all uropathogens. Tested carbapenems were found the most susceptible drug against isolated uropathogens which showed 92.26% and 84.52% susceptibility, respectively.

Bacteriuria amongst pregnant women in the Buea Health District, Cameroon: prevalence, predictors, antibiotic susceptibility patterns and diagnosis

Background

Bacteriuria is associated with significant maternal and foetal risks. However, its prevalence is not known in our community.

Objectives

This study was carried out to determine the prevalence and predictors of bacteriuria in pregnant women of the Buea Health District (BHD) as well as the antibiotic sensitivity patterns of bacterial isolates. It also sought to determine the diagnostic performance of the nitrite and leucocyte esterase tests in detecting bacteriuria in these women.

Methods

An observational analytic cross-sectional study was carried out amongst pregnant women attending selected antenatal care centres in Buea. We recruited 102 consenting pregnant women for the study. Demographic and clinical data were collected using structured questionnaires. Clean catch midstream urine was collected from each participant in sterile leak proof containers. Samples were examined biochemically, microscopically and by culture. Significant bacteriuria was defined as the presence of ≥10⁸ bacteria/L of cultured urine. Identification and susceptibility of isolates was performed using API 20E and ATB UR EU (08) (BioMerieux, Marcy l'Etoile, France).

Results

Significant bacteriuria was found in the urine of 24 of the 102 women tested giving a bacteriuria prevalence of 23.5% in pregnant women of the BHD. Asymptomatic bacteriuria was detected in 8(7.8%) of the women. There was no statistically significant predictor of bacteriuria. Escherichia coli were the most isolated (33%) uropathogens and were 100% sensitive to cefixime, cefoxitin and cephalothin. The nitrite and leucocyte esterase tests for determining bacteriuria had sensitivities of 8%, 20.8% and specificities of 98.7% and 80.8% respectively.

Conclusion

Bacteriuria is frequent in pregnant women in the BHD suggesting the need for routine screening by urine culture. Empiric treatment with cefixime should be instituted until results of urine culture and sensitivity are available. Nitrite and leucocyte esterase tests were not sensitive enough to replace urine culture as screening tests.

A real-time PCR-based semi-quantitative breakpoint to aid in molecular identification of urinary tract infections

This study presents a novel approach to aid in diagnosis of urinary tract infections (UTIs). A real-time PCR assay was used to screen for culture-positive urinary specimens and to identify the causative uropathogen. Semi-quantitative breakpoints were used to screen for significant bacteriuria (presence of ≥ 10(5) CFU/ml of uropathogens) or low-level bacteriuria (containing between 10(3) and 10(4) CFU/ml of uropathogens). The 16S rDNA-based assay could identify the most prevalent uropathogens using probes for Escherichia coli, Pseudomonas species, Pseudomonas aeruginosa, Staphylococcus species, Staphylococcus aureus, Enterococcus species and Streptococcus species. 330 urinary specimens were analysed and results were compared with conventional urine culture. Using a PCR Ct value of 25 as semi-quantitative breakpoint for significant bacteriuria resulted in a sensitivity and specificity of 97% and 80%, respectively. In 78% of the samples with monomicrobial infections the assay contained probes to detect the bacteria present in the urine specimens and 99% of these uropathogens was correctly identified. Concluding, this proof-of-concept approach demonstrates that the assay can distinguish bacteriuria from no bacteriuria as well as detect the involved uropathogen within 4 hours after sampling, allowing adequate therapy decisions within the same day as well as drastically reduce consequent urine culturing.

Enterococcus and Streptococcus spp. associated with chronic and self-medicated urinary tract infections in Vietnam

Background

Urinary tract infections (UTI) are one of the most common infections among women worldwide. E. coli often causes more than 75% of acute uncomplicated UTI, however, little is known about how recurrent UTIs and indiscriminate use of antimicrobials affect the aetiology of UTIs. This study aimed to establish the aetiology of UTI in a population of recurrent and self-medicated patients referred from pharmacies to a hospital in Hanoi, Vietnam and to describe genotypes and antimicrobial susceptibility of the associated bacterial pathogens. The aetiology of bacterial pathogens associated with UTI (defined as ≥ 10⁴ CFU/ml urine) was established by phenotypic and molecular methods. Enterococcus faecalis isolates were typed by Multi Locus Sequence Typing (MLST), Pulsed-Field Gel Electrophoresis (PFGE) and antimicrobial susceptibility testing.

Methods

Urine samples from 276 patients suffering symptoms of urinary tract infection were collected and cultured on Flexicult agar® allowing for detection of the most common urine pathogens. Patients were interviewed about underlying diseases, duration of symptoms, earlier episodes of UTI, number of episodes diagnosed by doctors and treatment in relation to UTI. All tentative E. faecalis and E. faecium isolates were identified to species level by PCR, 16S rRNA and partial sequencing of the groEL gene. E. faecalis isolates were further characterized by Multi Locus Sequence Typing and antimicrobial susceptibility testing.

Results

Mean age of 49 patients was 48 yrs (range was 11–86 yrs) and included 94% women. On average, patients reported to have suffered from UTI for 348 days (range 3 days-10 years, and experienced 2.7 UTIs during the previous year). Cephalosporins were reported the second drug of choice in treatment of UTI at the hospital. E. faecalis (55.1%), E. coli (12.2%) and Streptococcus gallolyticus subsp. pasteurianus (8.2%) were main bacterial pathogens. MIC testing of E. faecalis showed susceptibility to ampicillin, penicillin and vancomycin, but high-level resistance against gentamicin (48.1%). MLST revealed 12 Sequence Types (ST) of which ST 16 made up 44.5% and showed closely related PFGE types.

Conclusion

The different aetiology of UTI compared with reports elsewhere, where E. coli dominates, may be a result of chronic and recurrent UTIs together with indiscriminate use of antimicrobials. The similar genotypes shown by epidemiologically unrelated ST 16 isolates in Vietnam and elsewhere, suggest that E. faecalis ST 16 might represent a globally distributed clone. Treatment of UTI with cephalosporins may select for E. faecalis as it is intrinsic resistant and further studies are needed to establish the source(s) and role of E. faecalis ST 16 in acute UTI.

[Differences between species involved and fluoroquinolone resistance patterns of strains isolated from bacteriuria according to nosocomial, health-related or community-acquired onset]

PURPOSE

To describe and to compare species and antibiotics resistance patterns of bacteria involved among bacteriuria from hospital and city laboratories and among health-related and community-acquired bacteriuria.

METHODS

Epidemiologic transversal study conducted among Bacteriology laboratories of University Hospital (UH) and the whole city of Reims, during the week 21 to 26 June 2010. A standardized investigation form was completed after telephonical interview with the prescriber.

RESULTS

One hundred and eighty-nine strains have been isolated among 179 urocultures. One hundred and seven strains were isolated in city laboratories and 82 in UH laboratory. Strains were community-acquired, health-related and nosocomial in 136, 22 and 31 cases, respectively. More Gram positive bacteria and ofloxacin resistant strains were isolated among UH strains (P=0.001 and P=0.015, respectively) and among health-related strains (P=0.01 and P=0.003, respectively). When analysis was restricted only to Enterobacteriaceae or to Escherichia coli, the ofloxacin resistance rate was no more elevated among health-related or UH strains. Ofloxacin resistant Enterobacteriaceae were more frequently resistant to all other classes of antibiotics except nitrofurans.

DISCUSSION

Strains isolated in health-related bacteriuria are more frequently ofloxacin resistant principally because of the greater proportion of Gram positive bacteria and because of a non-significant higher ofloxacin resistance rate among Enterobacteriaceae. Numerous studies only focus on Enterobacteriaceae, and the data from our study need to be confirmed on larger samples, in order to validate the predictive value of health-related bacteriuria for ofloxacin resistance.

Rapid and sensitive detection of major uropathogens in a single-pot multiplex PCR assay

Urinary tract infection (UTI) is among the most common bacterial infections and poses a significant healthcare burden. Escherichia coli is the most common cause of UTI accounting for up to 70 % and a variable contribution from Proteus mirabilis, Pseudomonas aeruginosa and Klebsiella pneumoniae. To establish a complete diagnostic system, we have developed a single-tube multiplex PCR assay (mPCR) for the detection of the above-mentioned four major uropathogens. The sensitivity of the assay was found to be as low as 10(2) cfu/ml of cells. The mPCR evaluated on 280 clinical isolates detected 100 % of E. coli, P. aeruginosa, P. mirabilis and 95 % of K. pneumonia. The assay was performed on 50 urine samples and found to be specific and sensitive for clinical diagnosis. In addition, the mPCR was also validated on spiked urine samples using 40 clinical isolates to demonstrate its application under different strain used in this assay. In total, mPCR reported here is a rapid and simple screening tool that can compete with conventional biochemical-based screening assays that may require 2-3 days for detection.

Antibiotic resistance in urinary tract infections in college students

OBJECTIVE

To determine resistance to antibiotics of Escherichia coli in uncomplicated urinary tract infections (uUTIs) in female college students.

PARTICIPANTS

Symptomatic patients presenting to a student health service from September 2008 to December 2009.

METHODS

Clean catch midstream urine samples were tested for urinalysis (UA) and culture and sensitivity.

RESULTS

Of 168 students enrolled in the study, 138 had positive UA, and 94 of these grew >100,000 colonies/mL of E. coli. Ampicillin resistance was 31.9%, trimethoprim-sulfamethoxazole (TMP-SMX) resistance 16.0%, ciprofloxacin resistance 4.3%, amoxicillin/clavulanate resistance 3.2%, and nitrofurantoin resistance 1.1%. The sensitivity of UA was 95.4% and the positive predictive value was 87.0% (p ≤ .001). Specificity was 77.5% and negative predictive value 92.9%.

CONCLUSIONS

In healthy college women with uUTI symptoms, TMP-SMX should not be universally used for empirical therapy, whereas use of ciprofloxacin, amoxicillin/clavulanate, and nitrofurantoin are appropriate.

Does clinical examination aid in the diagnosis of urinary tract infections in women? A systematic review and meta-analysis

Background

Clinicians should be aware of the diagnostic values of various symptoms, signs and antecedents. This information is particularly important in primary care settings, where sophisticated diagnostic approaches are not always feasible. The aim of the study is to determine the probability that various symptoms, signs, antecedents and tests predict urinary tract infection (UTI) in women.

Methods

We conducted a systematic search of the MEDLINE and EMBASE databases to identify articles published in all languages through until December 2008. We particularly focused on studies that examined the diagnostic accuracy of at least one symptom, sign or patient antecedent related to the urinary tract. We included studies where urine culture, a gold standard, was preformed by primary care providers on female subjects aged at least 14 years. A meta-analysis of the likelihood ratio was performed to assess variables related to the urinary tract symptoms.

Results

Of the 1, 212 articles identified, 11 met the selection criteria. Dysuria, urgency, nocturia, sexual activity and urgency with dysuria were weak predictors of urinary tract infection, whereas increases in vaginal discharge and suprapubic pain were weak predictors of the absence of infection. Nitrites or leukocytes in the dipstick test are the only findings that clearly favored a diagnosis of UTI.

Conclusions

Clinical findings do not aid in the diagnosis of UTI among women who present with urinary symptoms. Vaginal discharge is a weak indicator of the absence of infection. The urine dipstick test was the most reliable tool for detecting UTI.

The changing pattern of antimicrobial resistance within 42,033 Escherichia coli isolates from nosocomial, community and urology patient-specific urinary tract infections, Dublin, 1999-2009

OBJECTIVE

To investigate the changing pattern of antimicrobial resistance in Escherichia coli urinary tract infection over an eleven year period, and to determine whether E. coli antibiotic resistance rates vary depending on whether the UTI represents a nosocomial, community acquired or urology patient specific infection.

PATIENT AND METHODS

A retrospective analysis of the 42,033 E. coli urine isolates from the 11-year period 1999-2009 in a single Dublin teaching hospital was performed. WHONET(TM) software was used to analyse the changing pattern of sensitivity and resistance of E. coli to commonly used antibiotics over the study period. The origins of the urine samples were stratified into three groups: inpatients with nosocomial UTIs; urine originating from the emergency department and general practice (community UTIs); and UTIs in urology patients.

RESULTS

Urinary tract infections in the urology patient population demonstrate higher antibiotic resistance rates than nosocomial or community UTIs. There were significant trends of increasing resistance over the 11-year period for ampicillin, trimethoprim, gentamicin and ciprofloxacin, and significant differences in co-amoxyclav, gentamicin, nitrofurantion and ciprofloxacin resistance rates depending on the sample origin. Ampicillin and trimethoprim were the least active agents against E. coli, with total 11-year resistance rates of 58.3 and 33.8%, respectively. The overall gentamicin resistance rate was 3.4% and is climbing at a rate of 0.7% per year (P < 0.001). Within the urology patient population the resistance rate was 6.4%. Ciprofloxacin resistance approaches 20% in the nosocomial UTI population and approaches 30% in the urology population; however, it remains a reasonable empirical antibiotic choice in this community, with an 11-year resistance rate of 10.6%.

CONCLUSIONS

E. coli remains the commonest infecting uropathogen in the community and hospital setting with its incidence climbing from 50 to 60% of UTIs over the 11-year period. Neither penicillins nor trimethoprim represent suitable empirical antimicrobials for UTI and ciprofloxacin resistance in this Dublin-based study renders it unsuitable empirical therapy for nosocomial UTIs and UTIs in the urology population. The dramatic 11-year rate increase in gentamicin resistance is of paramount concern.

Validating the prediction of lower urinary tract infection in primary care: sensitivity and specificity of urinary dipsticks and clinical scores in women

BACKGROUND

Dipsticks are one of the most commonly used near-patient tests in primary care, but few clinical or dipstick algorithms have been rigorously developed.

AIM

To confirm whether previously documented clinical and dipstick variables and algorithms predict laboratory diagnosis of urinary tract infection (UTI).

DESIGN OF STUDY

Validation study.

SETTING

Primary care.

METHOD

A total of 434 adult females with suspected lower UTI had bacteriuria assessed using the European Urinalysis Guidelines.

RESULTS

Sixty-six per cent of patients had confirmed UTI. The predictive values of nitrite, leucocyte esterase (+ or greater), and blood (haemolysed trace or greater) were confirmed (independent multivariate odds ratios = 5.6, 3.5, and 2.1 respectively). The previously developed dipstick rule--based on presence of nitrite, or both leucocytes and blood-- was moderately sensitive (75%) but less specific (66%; positive predictive value [PPV] 81%, negative predictive value [NPV] 57%). Predictive values were improved by varying the cut-off point: NPV was 76% for all three dipstick results being negative; the PPV was 92% for having nitrite and either blood or leucocyte esterase. Urine offensive smell was not found to be predictive in this sample; for a clinical score using the remaining three predictive clinical features (urine cloudiness, dysuria, and nocturia), NPV was 67% for none of the features, and PPV was 82% for three features.

CONCLUSION

A clinical score is of limited value in increasing diagnostic precision. Dipstick results can modestly improve diagnostic precision but poorly rule out infection. Clinicians need strategies to take account of poor NPVs.

Evolution of bacterial susceptibility pattern of Escherichia coli in uncomplicated urinary tract infections in a country with high antibiotic consumption: a comparison of two surveys with a 10 year interval

OBJECTIVES

For the empirical treatment of cystitis, clinicians are often guided by susceptibility data taken from urinary samples that sent to regional microbiological laboratories, which are not representatives for uncomplicated urinary tract infections (UTIs). To offer adequate recommendations, the distribution and susceptibility pattern of uropathogens in uncomplicated UTIs in women were compared with those obtained 10 years ago in our uropathogen surveillance in a primary healthcare setting.

METHODS

Sixty-six general practitioners in the region of the city of Ghent were asked to inoculate a dipslide with midstream urine from every adult female patient with complaints suggestive for cystitis, during a period of 1 year. The dipslides were further processed in a central microbiological laboratory, where counting, identification and susceptibility testing were performed.

RESULTS

Three hundred specimens were collected, of which 187 (62.3%) yielded a positive culture of 10(5) cfu/mL. In the age group of 18-54 years, Escherichia coli was the most frequently isolated uropathogen (77.5%), followed by Staphylococcus saprophyticus (13.5%) and Proteus spp. (2.7%). There were no statistically significant differences when compared with the data from 1996. In 2006, susceptibility of E. coli to nitrofurantoin was 100%, to quinolones 100%, to ampicillin 62.8% and to co-trimoxazole 86%, compared with 99.3%, 99.3%, 73.2% and 83.3%, respectively, in 1996 (no statistically significant differences).

CONCLUSIONS

Over a period of 10 years, a systematic surveillance of uropathogens in female patients with uncomplicated UTI in general practice could not demonstrate a significant change in species distribution or antimicrobial susceptibility.

Evaluation of the Nitrite and Leukocyte Esterase Activity Tests for the Diagnosis of Acute Symptomatic Urinary Tract Infection in Men

For 422 male patients with symptoms indicative of a urinary tract infection, nitrite and leukocyte esterase activity dipstick test results were compared with results of culture of urine samples. The positive predictive value of a positive nitrite test result was 96%. Addition of results of the leukocyte esterase test did not improve the diagnostic accuracy of the nitrite test.

Infections in the elderly

Infectious diseases remain a significant cause of morbidity and mortality in the growing number of adults over the age of 65 years in the United States. Declining immunity coupled with aging anatomy and physiology set the stage for increased vulnerability to infections and the development of atypical presentations in the elderly. Pneumonia, urinary tract infection, and skin and soft tissue infections are illnesses commonly encountered in the care of this unique population. This article explores the etiology, diagnosis, and constantly evolving treatment of these conditions in the context of the elderly patient.

An observational study of empirical antibiotics for adult women with uncomplicated UTI in general practice

OBJECTIVES

Women presenting in primary care with symptoms suggestive of uncomplicated urinary tract infection (UTI) are commonly managed without urine culture. We therefore do not know how successful general practitioners (GPs) are at targeting antibiotic treatment to women who would have had a microbiologically confirmed UTI, or at avoiding antibiotics in those who would have had a negative culture, had all patients with a suspected UTI been sampled. We therefore explored the association between antibiotic prescribing and urine culture results when culture was performed in all symptomatic patients.

METHODS

GPs in nine general practices in South Wales were asked to submit urine specimens from all women consulting with clinically suspected, uncomplicated UTI. Patients were followed up 2 weeks later by questionnaire.

RESULTS AND CONCLUSIONS

One hundred and thirteen adult women with a median age of 54 years were included and 61% received empirical antibiotics. There was very low agreement between the decision to prescribe empirically and subsequent culture result (Kappa = 0.04), with 60% of those prescribed empirical antibiotics subsequently found to have a negative culture, and 25% of those found to have a positive culture not prescribed empirical antibiotics. Current strategies to target empirical antibiotic prescribing in clinically suspected, uncomplicated UTI require review.